xref: /openbmc/u-boot/README (revision 1d2c0506)
1#
2# (C) Copyright 2000 - 2013
3# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
4#
5# SPDX-License-Identifier:	GPL-2.0+
6#
7
8Summary:
9========
10
11This directory contains the source code for U-Boot, a boot loader for
12Embedded boards based on PowerPC, ARM, MIPS and several other
13processors, which can be installed in a boot ROM and used to
14initialize and test the hardware or to download and run application
15code.
16
17The development of U-Boot is closely related to Linux: some parts of
18the source code originate in the Linux source tree, we have some
19header files in common, and special provision has been made to
20support booting of Linux images.
21
22Some attention has been paid to make this software easily
23configurable and extendable. For instance, all monitor commands are
24implemented with the same call interface, so that it's very easy to
25add new commands. Also, instead of permanently adding rarely used
26code (for instance hardware test utilities) to the monitor, you can
27load and run it dynamically.
28
29
30Status:
31=======
32
33In general, all boards for which a configuration option exists in the
34Makefile have been tested to some extent and can be considered
35"working". In fact, many of them are used in production systems.
36
37In case of problems see the CHANGELOG file to find out who contributed
38the specific port. In addition, there are various MAINTAINERS files
39scattered throughout the U-Boot source identifying the people or
40companies responsible for various boards and subsystems.
41
42Note: As of August, 2010, there is no longer a CHANGELOG file in the
43actual U-Boot source tree; however, it can be created dynamically
44from the Git log using:
45
46	make CHANGELOG
47
48
49Where to get help:
50==================
51
52In case you have questions about, problems with or contributions for
53U-Boot, you should send a message to the U-Boot mailing list at
54<u-boot@lists.denx.de>. There is also an archive of previous traffic
55on the mailing list - please search the archive before asking FAQ's.
56Please see http://lists.denx.de/pipermail/u-boot and
57http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
58
59
60Where to get source code:
61=========================
62
63The U-Boot source code is maintained in the Git repository at
64git://www.denx.de/git/u-boot.git ; you can browse it online at
65http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
66
67The "snapshot" links on this page allow you to download tarballs of
68any version you might be interested in. Official releases are also
69available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
70directory.
71
72Pre-built (and tested) images are available from
73ftp://ftp.denx.de/pub/u-boot/images/
74
75
76Where we come from:
77===================
78
79- start from 8xxrom sources
80- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
81- clean up code
82- make it easier to add custom boards
83- make it possible to add other [PowerPC] CPUs
84- extend functions, especially:
85  * Provide extended interface to Linux boot loader
86  * S-Record download
87  * network boot
88  * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
89- create ARMBoot project (http://sourceforge.net/projects/armboot)
90- add other CPU families (starting with ARM)
91- create U-Boot project (http://sourceforge.net/projects/u-boot)
92- current project page: see http://www.denx.de/wiki/U-Boot
93
94
95Names and Spelling:
96===================
97
98The "official" name of this project is "Das U-Boot". The spelling
99"U-Boot" shall be used in all written text (documentation, comments
100in source files etc.). Example:
101
102	This is the README file for the U-Boot project.
103
104File names etc. shall be based on the string "u-boot". Examples:
105
106	include/asm-ppc/u-boot.h
107
108	#include <asm/u-boot.h>
109
110Variable names, preprocessor constants etc. shall be either based on
111the string "u_boot" or on "U_BOOT". Example:
112
113	U_BOOT_VERSION		u_boot_logo
114	IH_OS_U_BOOT		u_boot_hush_start
115
116
117Versioning:
118===========
119
120Starting with the release in October 2008, the names of the releases
121were changed from numerical release numbers without deeper meaning
122into a time stamp based numbering. Regular releases are identified by
123names consisting of the calendar year and month of the release date.
124Additional fields (if present) indicate release candidates or bug fix
125releases in "stable" maintenance trees.
126
127Examples:
128	U-Boot v2009.11	    - Release November 2009
129	U-Boot v2009.11.1   - Release 1 in version November 2009 stable tree
130	U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release
131
132
133Directory Hierarchy:
134====================
135
136/arch			Architecture specific files
137  /arc			Files generic to ARC architecture
138  /arm			Files generic to ARM architecture
139  /avr32		Files generic to AVR32 architecture
140  /blackfin		Files generic to Analog Devices Blackfin architecture
141  /m68k			Files generic to m68k architecture
142  /microblaze		Files generic to microblaze architecture
143  /mips			Files generic to MIPS architecture
144  /nds32		Files generic to NDS32 architecture
145  /nios2		Files generic to Altera NIOS2 architecture
146  /openrisc		Files generic to OpenRISC architecture
147  /powerpc		Files generic to PowerPC architecture
148  /sandbox		Files generic to HW-independent "sandbox"
149  /sh			Files generic to SH architecture
150  /sparc		Files generic to SPARC architecture
151  /x86			Files generic to x86 architecture
152/api			Machine/arch independent API for external apps
153/board			Board dependent files
154/cmd			U-Boot commands functions
155/common			Misc architecture independent functions
156/configs		Board default configuration files
157/disk			Code for disk drive partition handling
158/doc			Documentation (don't expect too much)
159/drivers		Commonly used device drivers
160/dts			Contains Makefile for building internal U-Boot fdt.
161/examples		Example code for standalone applications, etc.
162/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
163/include		Header Files
164/lib			Library routines generic to all architectures
165/Licenses		Various license files
166/net			Networking code
167/post			Power On Self Test
168/scripts		Various build scripts and Makefiles
169/test			Various unit test files
170/tools			Tools to build S-Record or U-Boot images, etc.
171
172Software Configuration:
173=======================
174
175Configuration is usually done using C preprocessor defines; the
176rationale behind that is to avoid dead code whenever possible.
177
178There are two classes of configuration variables:
179
180* Configuration _OPTIONS_:
181  These are selectable by the user and have names beginning with
182  "CONFIG_".
183
184* Configuration _SETTINGS_:
185  These depend on the hardware etc. and should not be meddled with if
186  you don't know what you're doing; they have names beginning with
187  "CONFIG_SYS_".
188
189Previously, all configuration was done by hand, which involved creating
190symbolic links and editing configuration files manually. More recently,
191U-Boot has added the Kbuild infrastructure used by the Linux kernel,
192allowing you to use the "make menuconfig" command to configure your
193build.
194
195
196Selection of Processor Architecture and Board Type:
197---------------------------------------------------
198
199For all supported boards there are ready-to-use default
200configurations available; just type "make <board_name>_defconfig".
201
202Example: For a TQM823L module type:
203
204	cd u-boot
205	make TQM823L_defconfig
206
207Note: If you're looking for the default configuration file for a board
208you're sure used to be there but is now missing, check the file
209doc/README.scrapyard for a list of no longer supported boards.
210
211Sandbox Environment:
212--------------------
213
214U-Boot can be built natively to run on a Linux host using the 'sandbox'
215board. This allows feature development which is not board- or architecture-
216specific to be undertaken on a native platform. The sandbox is also used to
217run some of U-Boot's tests.
218
219See board/sandbox/README.sandbox for more details.
220
221
222Board Initialisation Flow:
223--------------------------
224
225This is the intended start-up flow for boards. This should apply for both
226SPL and U-Boot proper (i.e. they both follow the same rules).
227
228Note: "SPL" stands for "Secondary Program Loader," which is explained in
229more detail later in this file.
230
231At present, SPL mostly uses a separate code path, but the function names
232and roles of each function are the same. Some boards or architectures
233may not conform to this.  At least most ARM boards which use
234CONFIG_SPL_FRAMEWORK conform to this.
235
236Execution typically starts with an architecture-specific (and possibly
237CPU-specific) start.S file, such as:
238
239	- arch/arm/cpu/armv7/start.S
240	- arch/powerpc/cpu/mpc83xx/start.S
241	- arch/mips/cpu/start.S
242
243and so on. From there, three functions are called; the purpose and
244limitations of each of these functions are described below.
245
246lowlevel_init():
247	- purpose: essential init to permit execution to reach board_init_f()
248	- no global_data or BSS
249	- there is no stack (ARMv7 may have one but it will soon be removed)
250	- must not set up SDRAM or use console
251	- must only do the bare minimum to allow execution to continue to
252		board_init_f()
253	- this is almost never needed
254	- return normally from this function
255
256board_init_f():
257	- purpose: set up the machine ready for running board_init_r():
258		i.e. SDRAM and serial UART
259	- global_data is available
260	- stack is in SRAM
261	- BSS is not available, so you cannot use global/static variables,
262		only stack variables and global_data
263
264	Non-SPL-specific notes:
265	- dram_init() is called to set up DRAM. If already done in SPL this
266		can do nothing
267
268	SPL-specific notes:
269	- you can override the entire board_init_f() function with your own
270		version as needed.
271	- preloader_console_init() can be called here in extremis
272	- should set up SDRAM, and anything needed to make the UART work
273	- these is no need to clear BSS, it will be done by crt0.S
274	- must return normally from this function (don't call board_init_r()
275		directly)
276
277Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
278this point the stack and global_data are relocated to below
279CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
280memory.
281
282board_init_r():
283	- purpose: main execution, common code
284	- global_data is available
285	- SDRAM is available
286	- BSS is available, all static/global variables can be used
287	- execution eventually continues to main_loop()
288
289	Non-SPL-specific notes:
290	- U-Boot is relocated to the top of memory and is now running from
291		there.
292
293	SPL-specific notes:
294	- stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
295		CONFIG_SPL_STACK_R_ADDR points into SDRAM
296	- preloader_console_init() can be called here - typically this is
297		done by defining CONFIG_SPL_BOARD_INIT and then supplying a
298		spl_board_init() function containing this call
299	- loads U-Boot or (in falcon mode) Linux
300
301
302
303Configuration Options:
304----------------------
305
306Configuration depends on the combination of board and CPU type; all
307such information is kept in a configuration file
308"include/configs/<board_name>.h".
309
310Example: For a TQM823L module, all configuration settings are in
311"include/configs/TQM823L.h".
312
313
314Many of the options are named exactly as the corresponding Linux
315kernel configuration options. The intention is to make it easier to
316build a config tool - later.
317
318
319The following options need to be configured:
320
321- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
322
323- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
324
325- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
326		Define exactly one, e.g. CONFIG_ATSTK1002
327
328- Marvell Family Member
329		CONFIG_SYS_MVFS		- define it if you want to enable
330					  multiple fs option at one time
331					  for marvell soc family
332
333- 8xx CPU Options: (if using an MPC8xx CPU)
334		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
335					  get_gclk_freq() cannot work
336					  e.g. if there is no 32KHz
337					  reference PIT/RTC clock
338		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
339					  or XTAL/EXTAL)
340
341- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
342		CONFIG_SYS_8xx_CPUCLK_MIN
343		CONFIG_SYS_8xx_CPUCLK_MAX
344		CONFIG_8xx_CPUCLK_DEFAULT
345			See doc/README.MPC866
346
347		CONFIG_SYS_MEASURE_CPUCLK
348
349		Define this to measure the actual CPU clock instead
350		of relying on the correctness of the configured
351		values. Mostly useful for board bringup to make sure
352		the PLL is locked at the intended frequency. Note
353		that this requires a (stable) reference clock (32 kHz
354		RTC clock or CONFIG_SYS_8XX_XIN)
355
356		CONFIG_SYS_DELAYED_ICACHE
357
358		Define this option if you want to enable the
359		ICache only when Code runs from RAM.
360
361- 85xx CPU Options:
362		CONFIG_SYS_PPC64
363
364		Specifies that the core is a 64-bit PowerPC implementation (implements
365		the "64" category of the Power ISA). This is necessary for ePAPR
366		compliance, among other possible reasons.
367
368		CONFIG_SYS_FSL_TBCLK_DIV
369
370		Defines the core time base clock divider ratio compared to the
371		system clock.  On most PQ3 devices this is 8, on newer QorIQ
372		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
373
374		CONFIG_SYS_FSL_PCIE_COMPAT
375
376		Defines the string to utilize when trying to match PCIe device
377		tree nodes for the given platform.
378
379		CONFIG_SYS_FSL_ERRATUM_A004510
380
381		Enables a workaround for erratum A004510.  If set,
382		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
383		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
384
385		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
386		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
387
388		Defines one or two SoC revisions (low 8 bits of SVR)
389		for which the A004510 workaround should be applied.
390
391		The rest of SVR is either not relevant to the decision
392		of whether the erratum is present (e.g. p2040 versus
393		p2041) or is implied by the build target, which controls
394		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
395
396		See Freescale App Note 4493 for more information about
397		this erratum.
398
399		CONFIG_A003399_NOR_WORKAROUND
400		Enables a workaround for IFC erratum A003399. It is only
401		required during NOR boot.
402
403		CONFIG_A008044_WORKAROUND
404		Enables a workaround for T1040/T1042 erratum A008044. It is only
405		required during NAND boot and valid for Rev 1.0 SoC revision
406
407		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
408
409		This is the value to write into CCSR offset 0x18600
410		according to the A004510 workaround.
411
412		CONFIG_SYS_FSL_DSP_DDR_ADDR
413		This value denotes start offset of DDR memory which is
414		connected exclusively to the DSP cores.
415
416		CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
417		This value denotes start offset of M2 memory
418		which is directly connected to the DSP core.
419
420		CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
421		This value denotes start offset of M3 memory which is directly
422		connected to the DSP core.
423
424		CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
425		This value denotes start offset of DSP CCSR space.
426
427		CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
428		Single Source Clock is clocking mode present in some of FSL SoC's.
429		In this mode, a single differential clock is used to supply
430		clocks to the sysclock, ddrclock and usbclock.
431
432		CONFIG_SYS_CPC_REINIT_F
433		This CONFIG is defined when the CPC is configured as SRAM at the
434		time of U-Boot entry and is required to be re-initialized.
435
436		CONFIG_DEEP_SLEEP
437		Indicates this SoC supports deep sleep feature. If deep sleep is
438		supported, core will start to execute uboot when wakes up.
439
440- Generic CPU options:
441		CONFIG_SYS_GENERIC_GLOBAL_DATA
442		Defines global data is initialized in generic board board_init_f().
443		If this macro is defined, global data is created and cleared in
444		generic board board_init_f(). Without this macro, architecture/board
445		should initialize global data before calling board_init_f().
446
447		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
448
449		Defines the endianess of the CPU. Implementation of those
450		values is arch specific.
451
452		CONFIG_SYS_FSL_DDR
453		Freescale DDR driver in use. This type of DDR controller is
454		found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
455		SoCs.
456
457		CONFIG_SYS_FSL_DDR_ADDR
458		Freescale DDR memory-mapped register base.
459
460		CONFIG_SYS_FSL_DDR_EMU
461		Specify emulator support for DDR. Some DDR features such as
462		deskew training are not available.
463
464		CONFIG_SYS_FSL_DDRC_GEN1
465		Freescale DDR1 controller.
466
467		CONFIG_SYS_FSL_DDRC_GEN2
468		Freescale DDR2 controller.
469
470		CONFIG_SYS_FSL_DDRC_GEN3
471		Freescale DDR3 controller.
472
473		CONFIG_SYS_FSL_DDRC_GEN4
474		Freescale DDR4 controller.
475
476		CONFIG_SYS_FSL_DDRC_ARM_GEN3
477		Freescale DDR3 controller for ARM-based SoCs.
478
479		CONFIG_SYS_FSL_DDR1
480		Board config to use DDR1. It can be enabled for SoCs with
481		Freescale DDR1 or DDR2 controllers, depending on the board
482		implemetation.
483
484		CONFIG_SYS_FSL_DDR2
485		Board config to use DDR2. It can be enabled for SoCs with
486		Freescale DDR2 or DDR3 controllers, depending on the board
487		implementation.
488
489		CONFIG_SYS_FSL_DDR3
490		Board config to use DDR3. It can be enabled for SoCs with
491		Freescale DDR3 or DDR3L controllers.
492
493		CONFIG_SYS_FSL_DDR3L
494		Board config to use DDR3L. It can be enabled for SoCs with
495		DDR3L controllers.
496
497		CONFIG_SYS_FSL_DDR4
498		Board config to use DDR4. It can be enabled for SoCs with
499		DDR4 controllers.
500
501		CONFIG_SYS_FSL_IFC_BE
502		Defines the IFC controller register space as Big Endian
503
504		CONFIG_SYS_FSL_IFC_LE
505		Defines the IFC controller register space as Little Endian
506
507		CONFIG_SYS_FSL_PBL_PBI
508		It enables addition of RCW (Power on reset configuration) in built image.
509		Please refer doc/README.pblimage for more details
510
511		CONFIG_SYS_FSL_PBL_RCW
512		It adds PBI(pre-boot instructions) commands in u-boot build image.
513		PBI commands can be used to configure SoC before it starts the execution.
514		Please refer doc/README.pblimage for more details
515
516		CONFIG_SPL_FSL_PBL
517		It adds a target to create boot binary having SPL binary in PBI format
518		concatenated with u-boot binary.
519
520		CONFIG_SYS_FSL_DDR_BE
521		Defines the DDR controller register space as Big Endian
522
523		CONFIG_SYS_FSL_DDR_LE
524		Defines the DDR controller register space as Little Endian
525
526		CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
527		Physical address from the view of DDR controllers. It is the
528		same as CONFIG_SYS_DDR_SDRAM_BASE for  all Power SoCs. But
529		it could be different for ARM SoCs.
530
531		CONFIG_SYS_FSL_DDR_INTLV_256B
532		DDR controller interleaving on 256-byte. This is a special
533		interleaving mode, handled by Dickens for Freescale layerscape
534		SoCs with ARM core.
535
536		CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
537		Number of controllers used as main memory.
538
539		CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
540		Number of controllers used for other than main memory.
541
542		CONFIG_SYS_FSL_HAS_DP_DDR
543		Defines the SoC has DP-DDR used for DPAA.
544
545		CONFIG_SYS_FSL_SEC_BE
546		Defines the SEC controller register space as Big Endian
547
548		CONFIG_SYS_FSL_SEC_LE
549		Defines the SEC controller register space as Little Endian
550
551- MIPS CPU options:
552		CONFIG_SYS_INIT_SP_OFFSET
553
554		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
555		pointer. This is needed for the temporary stack before
556		relocation.
557
558		CONFIG_SYS_MIPS_CACHE_MODE
559
560		Cache operation mode for the MIPS CPU.
561		See also arch/mips/include/asm/mipsregs.h.
562		Possible values are:
563			CONF_CM_CACHABLE_NO_WA
564			CONF_CM_CACHABLE_WA
565			CONF_CM_UNCACHED
566			CONF_CM_CACHABLE_NONCOHERENT
567			CONF_CM_CACHABLE_CE
568			CONF_CM_CACHABLE_COW
569			CONF_CM_CACHABLE_CUW
570			CONF_CM_CACHABLE_ACCELERATED
571
572		CONFIG_SYS_XWAY_EBU_BOOTCFG
573
574		Special option for Lantiq XWAY SoCs for booting from NOR flash.
575		See also arch/mips/cpu/mips32/start.S.
576
577		CONFIG_XWAY_SWAP_BYTES
578
579		Enable compilation of tools/xway-swap-bytes needed for Lantiq
580		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
581		be swapped if a flash programmer is used.
582
583- ARM options:
584		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
585
586		Select high exception vectors of the ARM core, e.g., do not
587		clear the V bit of the c1 register of CP15.
588
589		CONFIG_SYS_THUMB_BUILD
590
591		Use this flag to build U-Boot using the Thumb instruction
592		set for ARM architectures. Thumb instruction set provides
593		better code density. For ARM architectures that support
594		Thumb2 this flag will result in Thumb2 code generated by
595		GCC.
596
597		CONFIG_ARM_ERRATA_716044
598		CONFIG_ARM_ERRATA_742230
599		CONFIG_ARM_ERRATA_743622
600		CONFIG_ARM_ERRATA_751472
601		CONFIG_ARM_ERRATA_761320
602		CONFIG_ARM_ERRATA_773022
603		CONFIG_ARM_ERRATA_774769
604		CONFIG_ARM_ERRATA_794072
605
606		If set, the workarounds for these ARM errata are applied early
607		during U-Boot startup. Note that these options force the
608		workarounds to be applied; no CPU-type/version detection
609		exists, unlike the similar options in the Linux kernel. Do not
610		set these options unless they apply!
611
612		COUNTER_FREQUENCY
613		Generic timer clock source frequency.
614
615		COUNTER_FREQUENCY_REAL
616		Generic timer clock source frequency if the real clock is
617		different from COUNTER_FREQUENCY, and can only be determined
618		at run time.
619
620		NOTE: The following can be machine specific errata. These
621		do have ability to provide rudimentary version and machine
622		specific checks, but expect no product checks.
623		CONFIG_ARM_ERRATA_430973
624		CONFIG_ARM_ERRATA_454179
625		CONFIG_ARM_ERRATA_621766
626		CONFIG_ARM_ERRATA_798870
627		CONFIG_ARM_ERRATA_801819
628
629- Tegra SoC options:
630		CONFIG_TEGRA_SUPPORT_NON_SECURE
631
632		Support executing U-Boot in non-secure (NS) mode. Certain
633		impossible actions will be skipped if the CPU is in NS mode,
634		such as ARM architectural timer initialization.
635
636- Linux Kernel Interface:
637		CONFIG_CLOCKS_IN_MHZ
638
639		U-Boot stores all clock information in Hz
640		internally. For binary compatibility with older Linux
641		kernels (which expect the clocks passed in the
642		bd_info data to be in MHz) the environment variable
643		"clocks_in_mhz" can be defined so that U-Boot
644		converts clock data to MHZ before passing it to the
645		Linux kernel.
646		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
647		"clocks_in_mhz=1" is automatically included in the
648		default environment.
649
650		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
651
652		When transferring memsize parameter to Linux, some versions
653		expect it to be in bytes, others in MB.
654		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
655
656		CONFIG_OF_LIBFDT
657
658		New kernel versions are expecting firmware settings to be
659		passed using flattened device trees (based on open firmware
660		concepts).
661
662		CONFIG_OF_LIBFDT
663		 * New libfdt-based support
664		 * Adds the "fdt" command
665		 * The bootm command automatically updates the fdt
666
667		OF_CPU - The proper name of the cpus node (only required for
668			MPC512X and MPC5xxx based boards).
669		OF_SOC - The proper name of the soc node (only required for
670			MPC512X and MPC5xxx based boards).
671		OF_TBCLK - The timebase frequency.
672		OF_STDOUT_PATH - The path to the console device
673
674		boards with QUICC Engines require OF_QE to set UCC MAC
675		addresses
676
677		CONFIG_OF_BOARD_SETUP
678
679		Board code has addition modification that it wants to make
680		to the flat device tree before handing it off to the kernel
681
682		CONFIG_OF_SYSTEM_SETUP
683
684		Other code has addition modification that it wants to make
685		to the flat device tree before handing it off to the kernel.
686		This causes ft_system_setup() to be called before booting
687		the kernel.
688
689		CONFIG_OF_IDE_FIXUP
690
691		U-Boot can detect if an IDE device is present or not.
692		If not, and this new config option is activated, U-Boot
693		removes the ATA node from the DTS before booting Linux,
694		so the Linux IDE driver does not probe the device and
695		crash. This is needed for buggy hardware (uc101) where
696		no pull down resistor is connected to the signal IDE5V_DD7.
697
698		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
699
700		This setting is mandatory for all boards that have only one
701		machine type and must be used to specify the machine type
702		number as it appears in the ARM machine registry
703		(see http://www.arm.linux.org.uk/developer/machines/).
704		Only boards that have multiple machine types supported
705		in a single configuration file and the machine type is
706		runtime discoverable, do not have to use this setting.
707
708- vxWorks boot parameters:
709
710		bootvx constructs a valid bootline using the following
711		environments variables: bootdev, bootfile, ipaddr, netmask,
712		serverip, gatewayip, hostname, othbootargs.
713		It loads the vxWorks image pointed bootfile.
714
715		Note: If a "bootargs" environment is defined, it will overwride
716		the defaults discussed just above.
717
718- Cache Configuration:
719		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
720		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
721		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
722
723- Cache Configuration for ARM:
724		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
725				      controller
726		CONFIG_SYS_PL310_BASE - Physical base address of PL310
727					controller register space
728
729- Serial Ports:
730		CONFIG_PL010_SERIAL
731
732		Define this if you want support for Amba PrimeCell PL010 UARTs.
733
734		CONFIG_PL011_SERIAL
735
736		Define this if you want support for Amba PrimeCell PL011 UARTs.
737
738		CONFIG_PL011_CLOCK
739
740		If you have Amba PrimeCell PL011 UARTs, set this variable to
741		the clock speed of the UARTs.
742
743		CONFIG_PL01x_PORTS
744
745		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
746		define this to a list of base addresses for each (supported)
747		port. See e.g. include/configs/versatile.h
748
749		CONFIG_SERIAL_HW_FLOW_CONTROL
750
751		Define this variable to enable hw flow control in serial driver.
752		Current user of this option is drivers/serial/nsl16550.c driver
753
754- Console Interface:
755		Depending on board, define exactly one serial port
756		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
757		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
758		console by defining CONFIG_8xx_CONS_NONE
759
760		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
761		port routines must be defined elsewhere
762		(i.e. serial_init(), serial_getc(), ...)
763
764- Console Baudrate:
765		CONFIG_BAUDRATE - in bps
766		Select one of the baudrates listed in
767		CONFIG_SYS_BAUDRATE_TABLE, see below.
768		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
769
770- Console Rx buffer length
771		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
772		the maximum receive buffer length for the SMC.
773		This option is actual only for 82xx and 8xx possible.
774		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
775		must be defined, to setup the maximum idle timeout for
776		the SMC.
777
778- Autoboot Command:
779		CONFIG_BOOTCOMMAND
780		Only needed when CONFIG_BOOTDELAY is enabled;
781		define a command string that is automatically executed
782		when no character is read on the console interface
783		within "Boot Delay" after reset.
784
785		CONFIG_BOOTARGS
786		This can be used to pass arguments to the bootm
787		command. The value of CONFIG_BOOTARGS goes into the
788		environment value "bootargs".
789
790		CONFIG_RAMBOOT and CONFIG_NFSBOOT
791		The value of these goes into the environment as
792		"ramboot" and "nfsboot" respectively, and can be used
793		as a convenience, when switching between booting from
794		RAM and NFS.
795
796- Bootcount:
797		CONFIG_BOOTCOUNT_LIMIT
798		Implements a mechanism for detecting a repeating reboot
799		cycle, see:
800		http://www.denx.de/wiki/view/DULG/UBootBootCountLimit
801
802		CONFIG_BOOTCOUNT_ENV
803		If no softreset save registers are found on the hardware
804		"bootcount" is stored in the environment. To prevent a
805		saveenv on all reboots, the environment variable
806		"upgrade_available" is used. If "upgrade_available" is
807		0, "bootcount" is always 0, if "upgrade_available" is
808		1 "bootcount" is incremented in the environment.
809		So the Userspace Applikation must set the "upgrade_available"
810		and "bootcount" variable to 0, if a boot was successfully.
811
812- Pre-Boot Commands:
813		CONFIG_PREBOOT
814
815		When this option is #defined, the existence of the
816		environment variable "preboot" will be checked
817		immediately before starting the CONFIG_BOOTDELAY
818		countdown and/or running the auto-boot command resp.
819		entering interactive mode.
820
821		This feature is especially useful when "preboot" is
822		automatically generated or modified. For an example
823		see the LWMON board specific code: here "preboot" is
824		modified when the user holds down a certain
825		combination of keys on the (special) keyboard when
826		booting the systems
827
828- Serial Download Echo Mode:
829		CONFIG_LOADS_ECHO
830		If defined to 1, all characters received during a
831		serial download (using the "loads" command) are
832		echoed back. This might be needed by some terminal
833		emulations (like "cu"), but may as well just take
834		time on others. This setting #define's the initial
835		value of the "loads_echo" environment variable.
836
837- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
838		CONFIG_KGDB_BAUDRATE
839		Select one of the baudrates listed in
840		CONFIG_SYS_BAUDRATE_TABLE, see below.
841
842- Monitor Functions:
843		Monitor commands can be included or excluded
844		from the build by using the #include files
845		<config_cmd_all.h> and #undef'ing unwanted
846		commands, or adding #define's for wanted commands.
847
848		The default command configuration includes all commands
849		except those marked below with a "*".
850
851		CONFIG_CMD_AES		  AES 128 CBC encrypt/decrypt
852		CONFIG_CMD_ASKENV	* ask for env variable
853		CONFIG_CMD_BDI		  bdinfo
854		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
855		CONFIG_CMD_BMP		* BMP support
856		CONFIG_CMD_BSP		* Board specific commands
857		CONFIG_CMD_BOOTD	  bootd
858		CONFIG_CMD_BOOTI	* ARM64 Linux kernel Image support
859		CONFIG_CMD_CACHE	* icache, dcache
860		CONFIG_CMD_CLK   	* clock command support
861		CONFIG_CMD_CONSOLE	  coninfo
862		CONFIG_CMD_CRC32	* crc32
863		CONFIG_CMD_DATE		* support for RTC, date/time...
864		CONFIG_CMD_DHCP		* DHCP support
865		CONFIG_CMD_DIAG		* Diagnostics
866		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
867		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
868		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
869		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
870		CONFIG_CMD_DTT		* Digital Therm and Thermostat
871		CONFIG_CMD_ECHO		  echo arguments
872		CONFIG_CMD_EDITENV	  edit env variable
873		CONFIG_CMD_EEPROM	* EEPROM read/write support
874		CONFIG_CMD_EEPROM_LAYOUT* EEPROM layout aware commands
875		CONFIG_CMD_ELF		* bootelf, bootvx
876		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
877		CONFIG_CMD_ENV_FLAGS	* display details about env flags
878		CONFIG_CMD_ENV_EXISTS	* check existence of env variable
879		CONFIG_CMD_EXPORTENV	* export the environment
880		CONFIG_CMD_EXT2		* ext2 command support
881		CONFIG_CMD_EXT4		* ext4 command support
882		CONFIG_CMD_FS_GENERIC	* filesystem commands (e.g. load, ls)
883					  that work for multiple fs types
884		CONFIG_CMD_FS_UUID	* Look up a filesystem UUID
885		CONFIG_CMD_SAVEENV	  saveenv
886		CONFIG_CMD_FDC		* Floppy Disk Support
887		CONFIG_CMD_FAT		* FAT command support
888		CONFIG_CMD_FLASH	  flinfo, erase, protect
889		CONFIG_CMD_FPGA		  FPGA device initialization support
890		CONFIG_CMD_FUSE		* Device fuse support
891		CONFIG_CMD_GETTIME	* Get time since boot
892		CONFIG_CMD_GO		* the 'go' command (exec code)
893		CONFIG_CMD_GREPENV	* search environment
894		CONFIG_CMD_HASH		* calculate hash / digest
895		CONFIG_CMD_I2C		* I2C serial bus support
896		CONFIG_CMD_IDE		* IDE harddisk support
897		CONFIG_CMD_IMI		  iminfo
898		CONFIG_CMD_IMLS		  List all images found in NOR flash
899		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash
900		CONFIG_CMD_IMMAP	* IMMR dump support
901		CONFIG_CMD_IOTRACE	* I/O tracing for debugging
902		CONFIG_CMD_IMPORTENV	* import an environment
903		CONFIG_CMD_INI		* import data from an ini file into the env
904		CONFIG_CMD_IRQ		* irqinfo
905		CONFIG_CMD_ITEST	  Integer/string test of 2 values
906		CONFIG_CMD_JFFS2	* JFFS2 Support
907		CONFIG_CMD_KGDB		* kgdb
908		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)
909		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
910					  (169.254.*.*)
911		CONFIG_CMD_LOADB	  loadb
912		CONFIG_CMD_LOADS	  loads
913		CONFIG_CMD_MD5SUM	* print md5 message digest
914					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
915		CONFIG_CMD_MEMINFO	* Display detailed memory information
916		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
917					  loop, loopw
918		CONFIG_CMD_MEMTEST	* mtest
919		CONFIG_CMD_MISC		  Misc functions like sleep etc
920		CONFIG_CMD_MMC		* MMC memory mapped support
921		CONFIG_CMD_MII		* MII utility commands
922		CONFIG_CMD_MTDPARTS	* MTD partition support
923		CONFIG_CMD_NAND		* NAND support
924		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
925		CONFIG_CMD_NFS		  NFS support
926		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
927		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
928		CONFIG_CMD_PCI		* pciinfo
929		CONFIG_CMD_PCMCIA		* PCMCIA support
930		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
931					  host
932		CONFIG_CMD_PORTIO	* Port I/O
933		CONFIG_CMD_READ		* Read raw data from partition
934		CONFIG_CMD_REGINFO	* Register dump
935		CONFIG_CMD_RUN		  run command in env variable
936		CONFIG_CMD_SANDBOX	* sb command to access sandbox features
937		CONFIG_CMD_SAVES	* save S record dump
938		CONFIG_SCSI		* SCSI Support
939		CONFIG_CMD_SDRAM	* print SDRAM configuration information
940					  (requires CONFIG_CMD_I2C)
941		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
942					  (4xx only)
943		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
944		CONFIG_CMD_SHA1SUM	* print sha1 memory digest
945					  (requires CONFIG_CMD_MEMORY)
946		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x
947		CONFIG_CMD_SOURCE	  "source" command Support
948		CONFIG_CMD_SPI		* SPI serial bus support
949		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
950		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
951		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
952		CONFIG_CMD_TIMER	* access to the system tick timer
953		CONFIG_CMD_USB		* USB support
954		CONFIG_CMD_CDP		* Cisco Discover Protocol support
955		CONFIG_CMD_MFSL		* Microblaze FSL support
956		CONFIG_CMD_XIMG		  Load part of Multi Image
957		CONFIG_CMD_UUID		* Generate random UUID or GUID string
958
959		EXAMPLE: If you want all functions except of network
960		support you can write:
961
962		#include "config_cmd_all.h"
963		#undef CONFIG_CMD_NET
964
965	Other Commands:
966		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
967
968	Note:	Don't enable the "icache" and "dcache" commands
969		(configuration option CONFIG_CMD_CACHE) unless you know
970		what you (and your U-Boot users) are doing. Data
971		cache cannot be enabled on systems like the 8xx or
972		8260 (where accesses to the IMMR region must be
973		uncached), and it cannot be disabled on all other
974		systems where we (mis-) use the data cache to hold an
975		initial stack and some data.
976
977
978		XXX - this list needs to get updated!
979
980- Removal of commands
981		If no commands are needed to boot, you can disable
982		CONFIG_CMDLINE to remove them. In this case, the command line
983		will not be available, and when U-Boot wants to execute the
984		boot command (on start-up) it will call board_run_command()
985		instead. This can reduce image size significantly for very
986		simple boot procedures.
987
988- Regular expression support:
989		CONFIG_REGEX
990		If this variable is defined, U-Boot is linked against
991		the SLRE (Super Light Regular Expression) library,
992		which adds regex support to some commands, as for
993		example "env grep" and "setexpr".
994
995- Device tree:
996		CONFIG_OF_CONTROL
997		If this variable is defined, U-Boot will use a device tree
998		to configure its devices, instead of relying on statically
999		compiled #defines in the board file. This option is
1000		experimental and only available on a few boards. The device
1001		tree is available in the global data as gd->fdt_blob.
1002
1003		U-Boot needs to get its device tree from somewhere. This can
1004		be done using one of the two options below:
1005
1006		CONFIG_OF_EMBED
1007		If this variable is defined, U-Boot will embed a device tree
1008		binary in its image. This device tree file should be in the
1009		board directory and called <soc>-<board>.dts. The binary file
1010		is then picked up in board_init_f() and made available through
1011		the global data structure as gd->blob.
1012
1013		CONFIG_OF_SEPARATE
1014		If this variable is defined, U-Boot will build a device tree
1015		binary. It will be called u-boot.dtb. Architecture-specific
1016		code will locate it at run-time. Generally this works by:
1017
1018			cat u-boot.bin u-boot.dtb >image.bin
1019
1020		and in fact, U-Boot does this for you, creating a file called
1021		u-boot-dtb.bin which is useful in the common case. You can
1022		still use the individual files if you need something more
1023		exotic.
1024
1025- Watchdog:
1026		CONFIG_WATCHDOG
1027		If this variable is defined, it enables watchdog
1028		support for the SoC. There must be support in the SoC
1029		specific code for a watchdog. For the 8xx and 8260
1030		CPUs, the SIU Watchdog feature is enabled in the SYPCR
1031		register.  When supported for a specific SoC is
1032		available, then no further board specific code should
1033		be needed to use it.
1034
1035		CONFIG_HW_WATCHDOG
1036		When using a watchdog circuitry external to the used
1037		SoC, then define this variable and provide board
1038		specific code for the "hw_watchdog_reset" function.
1039
1040		CONFIG_AT91_HW_WDT_TIMEOUT
1041		specify the timeout in seconds. default 2 seconds.
1042
1043- U-Boot Version:
1044		CONFIG_VERSION_VARIABLE
1045		If this variable is defined, an environment variable
1046		named "ver" is created by U-Boot showing the U-Boot
1047		version as printed by the "version" command.
1048		Any change to this variable will be reverted at the
1049		next reset.
1050
1051- Real-Time Clock:
1052
1053		When CONFIG_CMD_DATE is selected, the type of the RTC
1054		has to be selected, too. Define exactly one of the
1055		following options:
1056
1057		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
1058		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
1059		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
1060		CONFIG_RTC_MC146818	- use MC146818 RTC
1061		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
1062		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
1063		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
1064		CONFIG_RTC_DS1339	- use Maxim, Inc. DS1339 RTC
1065		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
1066		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
1067		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
1068		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
1069		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
1070					  RV3029 RTC.
1071
1072		Note that if the RTC uses I2C, then the I2C interface
1073		must also be configured. See I2C Support, below.
1074
1075- GPIO Support:
1076		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
1077
1078		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1079		chip-ngpio pairs that tell the PCA953X driver the number of
1080		pins supported by a particular chip.
1081
1082		Note that if the GPIO device uses I2C, then the I2C interface
1083		must also be configured. See I2C Support, below.
1084
1085- I/O tracing:
1086		When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
1087		accesses and can checksum them or write a list of them out
1088		to memory. See the 'iotrace' command for details. This is
1089		useful for testing device drivers since it can confirm that
1090		the driver behaves the same way before and after a code
1091		change. Currently this is supported on sandbox and arm. To
1092		add support for your architecture, add '#include <iotrace.h>'
1093		to the bottom of arch/<arch>/include/asm/io.h and test.
1094
1095		Example output from the 'iotrace stats' command is below.
1096		Note that if the trace buffer is exhausted, the checksum will
1097		still continue to operate.
1098
1099			iotrace is enabled
1100			Start:  10000000	(buffer start address)
1101			Size:   00010000	(buffer size)
1102			Offset: 00000120	(current buffer offset)
1103			Output: 10000120	(start + offset)
1104			Count:  00000018	(number of trace records)
1105			CRC32:  9526fb66	(CRC32 of all trace records)
1106
1107- Timestamp Support:
1108
1109		When CONFIG_TIMESTAMP is selected, the timestamp
1110		(date and time) of an image is printed by image
1111		commands like bootm or iminfo. This option is
1112		automatically enabled when you select CONFIG_CMD_DATE .
1113
1114- Partition Labels (disklabels) Supported:
1115		Zero or more of the following:
1116		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1117		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1118				       Intel architecture, USB sticks, etc.
1119		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1120		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1121				       bootloader.  Note 2TB partition limit; see
1122				       disk/part_efi.c
1123		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1124
1125		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1126		CONFIG_SCSI) you must configure support for at
1127		least one non-MTD partition type as well.
1128
1129- IDE Reset method:
1130		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1131		board configurations files but used nowhere!
1132
1133		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1134		be performed by calling the function
1135			ide_set_reset(int reset)
1136		which has to be defined in a board specific file
1137
1138- ATAPI Support:
1139		CONFIG_ATAPI
1140
1141		Set this to enable ATAPI support.
1142
1143- LBA48 Support
1144		CONFIG_LBA48
1145
1146		Set this to enable support for disks larger than 137GB
1147		Also look at CONFIG_SYS_64BIT_LBA.
1148		Whithout these , LBA48 support uses 32bit variables and will 'only'
1149		support disks up to 2.1TB.
1150
1151		CONFIG_SYS_64BIT_LBA:
1152			When enabled, makes the IDE subsystem use 64bit sector addresses.
1153			Default is 32bit.
1154
1155- SCSI Support:
1156		At the moment only there is only support for the
1157		SYM53C8XX SCSI controller; define
1158		CONFIG_SCSI_SYM53C8XX to enable it.
1159
1160		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1161		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1162		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1163		maximum numbers of LUNs, SCSI ID's and target
1164		devices.
1165		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1166
1167		The environment variable 'scsidevs' is set to the number of
1168		SCSI devices found during the last scan.
1169
1170- NETWORK Support (PCI):
1171		CONFIG_E1000
1172		Support for Intel 8254x/8257x gigabit chips.
1173
1174		CONFIG_E1000_SPI
1175		Utility code for direct access to the SPI bus on Intel 8257x.
1176		This does not do anything useful unless you set at least one
1177		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1178
1179		CONFIG_E1000_SPI_GENERIC
1180		Allow generic access to the SPI bus on the Intel 8257x, for
1181		example with the "sspi" command.
1182
1183		CONFIG_CMD_E1000
1184		Management command for E1000 devices.  When used on devices
1185		with SPI support you can reprogram the EEPROM from U-Boot.
1186
1187		CONFIG_EEPRO100
1188		Support for Intel 82557/82559/82559ER chips.
1189		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1190		write routine for first time initialisation.
1191
1192		CONFIG_TULIP
1193		Support for Digital 2114x chips.
1194		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1195		modem chip initialisation (KS8761/QS6611).
1196
1197		CONFIG_NATSEMI
1198		Support for National dp83815 chips.
1199
1200		CONFIG_NS8382X
1201		Support for National dp8382[01] gigabit chips.
1202
1203- NETWORK Support (other):
1204
1205		CONFIG_DRIVER_AT91EMAC
1206		Support for AT91RM9200 EMAC.
1207
1208			CONFIG_RMII
1209			Define this to use reduced MII inteface
1210
1211			CONFIG_DRIVER_AT91EMAC_QUIET
1212			If this defined, the driver is quiet.
1213			The driver doen't show link status messages.
1214
1215		CONFIG_CALXEDA_XGMAC
1216		Support for the Calxeda XGMAC device
1217
1218		CONFIG_LAN91C96
1219		Support for SMSC's LAN91C96 chips.
1220
1221			CONFIG_LAN91C96_USE_32_BIT
1222			Define this to enable 32 bit addressing
1223
1224		CONFIG_SMC91111
1225		Support for SMSC's LAN91C111 chip
1226
1227			CONFIG_SMC91111_BASE
1228			Define this to hold the physical address
1229			of the device (I/O space)
1230
1231			CONFIG_SMC_USE_32_BIT
1232			Define this if data bus is 32 bits
1233
1234			CONFIG_SMC_USE_IOFUNCS
1235			Define this to use i/o functions instead of macros
1236			(some hardware wont work with macros)
1237
1238		CONFIG_DRIVER_TI_EMAC
1239		Support for davinci emac
1240
1241			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1242			Define this if you have more then 3 PHYs.
1243
1244		CONFIG_FTGMAC100
1245		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1246
1247			CONFIG_FTGMAC100_EGIGA
1248			Define this to use GE link update with gigabit PHY.
1249			Define this if FTGMAC100 is connected to gigabit PHY.
1250			If your system has 10/100 PHY only, it might not occur
1251			wrong behavior. Because PHY usually return timeout or
1252			useless data when polling gigabit status and gigabit
1253			control registers. This behavior won't affect the
1254			correctnessof 10/100 link speed update.
1255
1256		CONFIG_SMC911X
1257		Support for SMSC's LAN911x and LAN921x chips
1258
1259			CONFIG_SMC911X_BASE
1260			Define this to hold the physical address
1261			of the device (I/O space)
1262
1263			CONFIG_SMC911X_32_BIT
1264			Define this if data bus is 32 bits
1265
1266			CONFIG_SMC911X_16_BIT
1267			Define this if data bus is 16 bits. If your processor
1268			automatically converts one 32 bit word to two 16 bit
1269			words you may also try CONFIG_SMC911X_32_BIT.
1270
1271		CONFIG_SH_ETHER
1272		Support for Renesas on-chip Ethernet controller
1273
1274			CONFIG_SH_ETHER_USE_PORT
1275			Define the number of ports to be used
1276
1277			CONFIG_SH_ETHER_PHY_ADDR
1278			Define the ETH PHY's address
1279
1280			CONFIG_SH_ETHER_CACHE_WRITEBACK
1281			If this option is set, the driver enables cache flush.
1282
1283- PWM Support:
1284		CONFIG_PWM_IMX
1285		Support for PWM module on the imx6.
1286
1287- TPM Support:
1288		CONFIG_TPM
1289		Support TPM devices.
1290
1291		CONFIG_TPM_TIS_INFINEON
1292		Support for Infineon i2c bus TPM devices. Only one device
1293		per system is supported at this time.
1294
1295			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1296			Define the burst count bytes upper limit
1297
1298		CONFIG_TPM_ST33ZP24
1299		Support for STMicroelectronics TPM devices. Requires DM_TPM support.
1300
1301			CONFIG_TPM_ST33ZP24_I2C
1302			Support for STMicroelectronics ST33ZP24 I2C devices.
1303			Requires TPM_ST33ZP24 and I2C.
1304
1305			CONFIG_TPM_ST33ZP24_SPI
1306			Support for STMicroelectronics ST33ZP24 SPI devices.
1307			Requires TPM_ST33ZP24 and SPI.
1308
1309		CONFIG_TPM_ATMEL_TWI
1310		Support for Atmel TWI TPM device. Requires I2C support.
1311
1312		CONFIG_TPM_TIS_LPC
1313		Support for generic parallel port TPM devices. Only one device
1314		per system is supported at this time.
1315
1316			CONFIG_TPM_TIS_BASE_ADDRESS
1317			Base address where the generic TPM device is mapped
1318			to. Contemporary x86 systems usually map it at
1319			0xfed40000.
1320
1321		CONFIG_CMD_TPM
1322		Add tpm monitor functions.
1323		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1324		provides monitor access to authorized functions.
1325
1326		CONFIG_TPM
1327		Define this to enable the TPM support library which provides
1328		functional interfaces to some TPM commands.
1329		Requires support for a TPM device.
1330
1331		CONFIG_TPM_AUTH_SESSIONS
1332		Define this to enable authorized functions in the TPM library.
1333		Requires CONFIG_TPM and CONFIG_SHA1.
1334
1335- USB Support:
1336		At the moment only the UHCI host controller is
1337		supported (PIP405, MIP405, MPC5200); define
1338		CONFIG_USB_UHCI to enable it.
1339		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1340		and define CONFIG_USB_STORAGE to enable the USB
1341		storage devices.
1342		Note:
1343		Supported are USB Keyboards and USB Floppy drives
1344		(TEAC FD-05PUB).
1345		MPC5200 USB requires additional defines:
1346			CONFIG_USB_CLOCK
1347				for 528 MHz Clock: 0x0001bbbb
1348			CONFIG_PSC3_USB
1349				for USB on PSC3
1350			CONFIG_USB_CONFIG
1351				for differential drivers: 0x00001000
1352				for single ended drivers: 0x00005000
1353				for differential drivers on PSC3: 0x00000100
1354				for single ended drivers on PSC3: 0x00004100
1355			CONFIG_SYS_USB_EVENT_POLL
1356				May be defined to allow interrupt polling
1357				instead of using asynchronous interrupts
1358
1359		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1360		txfilltuning field in the EHCI controller on reset.
1361
1362		CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
1363		HW module registers.
1364
1365- USB Device:
1366		Define the below if you wish to use the USB console.
1367		Once firmware is rebuilt from a serial console issue the
1368		command "setenv stdin usbtty; setenv stdout usbtty" and
1369		attach your USB cable. The Unix command "dmesg" should print
1370		it has found a new device. The environment variable usbtty
1371		can be set to gserial or cdc_acm to enable your device to
1372		appear to a USB host as a Linux gserial device or a
1373		Common Device Class Abstract Control Model serial device.
1374		If you select usbtty = gserial you should be able to enumerate
1375		a Linux host by
1376		# modprobe usbserial vendor=0xVendorID product=0xProductID
1377		else if using cdc_acm, simply setting the environment
1378		variable usbtty to be cdc_acm should suffice. The following
1379		might be defined in YourBoardName.h
1380
1381			CONFIG_USB_DEVICE
1382			Define this to build a UDC device
1383
1384			CONFIG_USB_TTY
1385			Define this to have a tty type of device available to
1386			talk to the UDC device
1387
1388			CONFIG_USBD_HS
1389			Define this to enable the high speed support for usb
1390			device and usbtty. If this feature is enabled, a routine
1391			int is_usbd_high_speed(void)
1392			also needs to be defined by the driver to dynamically poll
1393			whether the enumeration has succeded at high speed or full
1394			speed.
1395
1396			CONFIG_SYS_CONSOLE_IS_IN_ENV
1397			Define this if you want stdin, stdout &/or stderr to
1398			be set to usbtty.
1399
1400			mpc8xx:
1401				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1402				Derive USB clock from external clock "blah"
1403				- CONFIG_SYS_USB_EXTC_CLK 0x02
1404
1405		If you have a USB-IF assigned VendorID then you may wish to
1406		define your own vendor specific values either in BoardName.h
1407		or directly in usbd_vendor_info.h. If you don't define
1408		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1409		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1410		should pretend to be a Linux device to it's target host.
1411
1412			CONFIG_USBD_MANUFACTURER
1413			Define this string as the name of your company for
1414			- CONFIG_USBD_MANUFACTURER "my company"
1415
1416			CONFIG_USBD_PRODUCT_NAME
1417			Define this string as the name of your product
1418			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1419
1420			CONFIG_USBD_VENDORID
1421			Define this as your assigned Vendor ID from the USB
1422			Implementors Forum. This *must* be a genuine Vendor ID
1423			to avoid polluting the USB namespace.
1424			- CONFIG_USBD_VENDORID 0xFFFF
1425
1426			CONFIG_USBD_PRODUCTID
1427			Define this as the unique Product ID
1428			for your device
1429			- CONFIG_USBD_PRODUCTID 0xFFFF
1430
1431- ULPI Layer Support:
1432		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1433		the generic ULPI layer. The generic layer accesses the ULPI PHY
1434		via the platform viewport, so you need both the genric layer and
1435		the viewport enabled. Currently only Chipidea/ARC based
1436		viewport is supported.
1437		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1438		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1439		If your ULPI phy needs a different reference clock than the
1440		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1441		the appropriate value in Hz.
1442
1443- MMC Support:
1444		The MMC controller on the Intel PXA is supported. To
1445		enable this define CONFIG_MMC. The MMC can be
1446		accessed from the boot prompt by mapping the device
1447		to physical memory similar to flash. Command line is
1448		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1449		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1450
1451		CONFIG_SH_MMCIF
1452		Support for Renesas on-chip MMCIF controller
1453
1454			CONFIG_SH_MMCIF_ADDR
1455			Define the base address of MMCIF registers
1456
1457			CONFIG_SH_MMCIF_CLK
1458			Define the clock frequency for MMCIF
1459
1460		CONFIG_GENERIC_MMC
1461		Enable the generic MMC driver
1462
1463		CONFIG_SUPPORT_EMMC_BOOT
1464		Enable some additional features of the eMMC boot partitions.
1465
1466		CONFIG_SUPPORT_EMMC_RPMB
1467		Enable the commands for reading, writing and programming the
1468		key for the Replay Protection Memory Block partition in eMMC.
1469
1470- USB Device Firmware Update (DFU) class support:
1471		CONFIG_USB_FUNCTION_DFU
1472		This enables the USB portion of the DFU USB class
1473
1474		CONFIG_CMD_DFU
1475		This enables the command "dfu" which is used to have
1476		U-Boot create a DFU class device via USB.  This command
1477		requires that the "dfu_alt_info" environment variable be
1478		set and define the alt settings to expose to the host.
1479
1480		CONFIG_DFU_MMC
1481		This enables support for exposing (e)MMC devices via DFU.
1482
1483		CONFIG_DFU_NAND
1484		This enables support for exposing NAND devices via DFU.
1485
1486		CONFIG_DFU_RAM
1487		This enables support for exposing RAM via DFU.
1488		Note: DFU spec refer to non-volatile memory usage, but
1489		allow usages beyond the scope of spec - here RAM usage,
1490		one that would help mostly the developer.
1491
1492		CONFIG_SYS_DFU_DATA_BUF_SIZE
1493		Dfu transfer uses a buffer before writing data to the
1494		raw storage device. Make the size (in bytes) of this buffer
1495		configurable. The size of this buffer is also configurable
1496		through the "dfu_bufsiz" environment variable.
1497
1498		CONFIG_SYS_DFU_MAX_FILE_SIZE
1499		When updating files rather than the raw storage device,
1500		we use a static buffer to copy the file into and then write
1501		the buffer once we've been given the whole file.  Define
1502		this to the maximum filesize (in bytes) for the buffer.
1503		Default is 4 MiB if undefined.
1504
1505		DFU_DEFAULT_POLL_TIMEOUT
1506		Poll timeout [ms], is the timeout a device can send to the
1507		host. The host must wait for this timeout before sending
1508		a subsequent DFU_GET_STATUS request to the device.
1509
1510		DFU_MANIFEST_POLL_TIMEOUT
1511		Poll timeout [ms], which the device sends to the host when
1512		entering dfuMANIFEST state. Host waits this timeout, before
1513		sending again an USB request to the device.
1514
1515- USB Device Android Fastboot support:
1516		CONFIG_USB_FUNCTION_FASTBOOT
1517		This enables the USB part of the fastboot gadget
1518
1519		CONFIG_CMD_FASTBOOT
1520		This enables the command "fastboot" which enables the Android
1521		fastboot mode for the platform's USB device. Fastboot is a USB
1522		protocol for downloading images, flashing and device control
1523		used on Android devices.
1524		See doc/README.android-fastboot for more information.
1525
1526		CONFIG_ANDROID_BOOT_IMAGE
1527		This enables support for booting images which use the Android
1528		image format header.
1529
1530		CONFIG_FASTBOOT_BUF_ADDR
1531		The fastboot protocol requires a large memory buffer for
1532		downloads. Define this to the starting RAM address to use for
1533		downloaded images.
1534
1535		CONFIG_FASTBOOT_BUF_SIZE
1536		The fastboot protocol requires a large memory buffer for
1537		downloads. This buffer should be as large as possible for a
1538		platform. Define this to the size available RAM for fastboot.
1539
1540		CONFIG_FASTBOOT_FLASH
1541		The fastboot protocol includes a "flash" command for writing
1542		the downloaded image to a non-volatile storage device. Define
1543		this to enable the "fastboot flash" command.
1544
1545		CONFIG_FASTBOOT_FLASH_MMC_DEV
1546		The fastboot "flash" command requires additional information
1547		regarding the non-volatile storage device. Define this to
1548		the eMMC device that fastboot should use to store the image.
1549
1550		CONFIG_FASTBOOT_GPT_NAME
1551		The fastboot "flash" command supports writing the downloaded
1552		image to the Protective MBR and the Primary GUID Partition
1553		Table. (Additionally, this downloaded image is post-processed
1554		to generate and write the Backup GUID Partition Table.)
1555		This occurs when the specified "partition name" on the
1556		"fastboot flash" command line matches this value.
1557		The default is "gpt" if undefined.
1558
1559		CONFIG_FASTBOOT_MBR_NAME
1560		The fastboot "flash" command supports writing the downloaded
1561		image to DOS MBR.
1562		This occurs when the "partition name" specified on the
1563		"fastboot flash" command line matches this value.
1564		If not defined the default value "mbr" is used.
1565
1566- Journaling Flash filesystem support:
1567		CONFIG_JFFS2_NAND
1568		Define these for a default partition on a NAND device
1569
1570		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1571		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1572		Define these for a default partition on a NOR device
1573
1574- FAT(File Allocation Table) filesystem write function support:
1575		CONFIG_FAT_WRITE
1576
1577		Define this to enable support for saving memory data as a
1578		file in FAT formatted partition.
1579
1580		This will also enable the command "fatwrite" enabling the
1581		user to write files to FAT.
1582
1583- CBFS (Coreboot Filesystem) support:
1584		CONFIG_CMD_CBFS
1585
1586		Define this to enable support for reading from a Coreboot
1587		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1588		and cbfsload.
1589
1590- FAT(File Allocation Table) filesystem cluster size:
1591		CONFIG_FS_FAT_MAX_CLUSTSIZE
1592
1593		Define the max cluster size for fat operations else
1594		a default value of 65536 will be defined.
1595
1596- Keyboard Support:
1597		See Kconfig help for available keyboard drivers.
1598
1599		CONFIG_KEYBOARD
1600
1601		Define this to enable a custom keyboard support.
1602		This simply calls drv_keyboard_init() which must be
1603		defined in your board-specific files. This option is deprecated
1604		and is only used by novena. For new boards, use driver model
1605		instead.
1606
1607- Video support:
1608		CONFIG_FSL_DIU_FB
1609		Enable the Freescale DIU video driver.	Reference boards for
1610		SOCs that have a DIU should define this macro to enable DIU
1611		support, and should also define these other macros:
1612
1613			CONFIG_SYS_DIU_ADDR
1614			CONFIG_VIDEO
1615			CONFIG_CMD_BMP
1616			CONFIG_CFB_CONSOLE
1617			CONFIG_VIDEO_SW_CURSOR
1618			CONFIG_VGA_AS_SINGLE_DEVICE
1619			CONFIG_VIDEO_LOGO
1620			CONFIG_VIDEO_BMP_LOGO
1621
1622		The DIU driver will look for the 'video-mode' environment
1623		variable, and if defined, enable the DIU as a console during
1624		boot.  See the documentation file doc/README.video for a
1625		description of this variable.
1626
1627- LCD Support:	CONFIG_LCD
1628
1629		Define this to enable LCD support (for output to LCD
1630		display); also select one of the supported displays
1631		by defining one of these:
1632
1633		CONFIG_ATMEL_LCD:
1634
1635			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1636
1637		CONFIG_NEC_NL6448AC33:
1638
1639			NEC NL6448AC33-18. Active, color, single scan.
1640
1641		CONFIG_NEC_NL6448BC20
1642
1643			NEC NL6448BC20-08. 6.5", 640x480.
1644			Active, color, single scan.
1645
1646		CONFIG_NEC_NL6448BC33_54
1647
1648			NEC NL6448BC33-54. 10.4", 640x480.
1649			Active, color, single scan.
1650
1651		CONFIG_SHARP_16x9
1652
1653			Sharp 320x240. Active, color, single scan.
1654			It isn't 16x9, and I am not sure what it is.
1655
1656		CONFIG_SHARP_LQ64D341
1657
1658			Sharp LQ64D341 display, 640x480.
1659			Active, color, single scan.
1660
1661		CONFIG_HLD1045
1662
1663			HLD1045 display, 640x480.
1664			Active, color, single scan.
1665
1666		CONFIG_OPTREX_BW
1667
1668			Optrex	 CBL50840-2 NF-FW 99 22 M5
1669			or
1670			Hitachi	 LMG6912RPFC-00T
1671			or
1672			Hitachi	 SP14Q002
1673
1674			320x240. Black & white.
1675
1676		Normally display is black on white background; define
1677		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1678
1679		CONFIG_LCD_ALIGNMENT
1680
1681		Normally the LCD is page-aligned (typically 4KB). If this is
1682		defined then the LCD will be aligned to this value instead.
1683		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1684		here, since it is cheaper to change data cache settings on
1685		a per-section basis.
1686
1687
1688		CONFIG_LCD_ROTATION
1689
1690		Sometimes, for example if the display is mounted in portrait
1691		mode or even if it's mounted landscape but rotated by 180degree,
1692		we need to rotate our content of the display relative to the
1693		framebuffer, so that user can read the messages which are
1694		printed out.
1695		Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1696		initialized with a given rotation from "vl_rot" out of
1697		"vidinfo_t" which is provided by the board specific code.
1698		The value for vl_rot is coded as following (matching to
1699		fbcon=rotate:<n> linux-kernel commandline):
1700		0 = no rotation respectively 0 degree
1701		1 = 90 degree rotation
1702		2 = 180 degree rotation
1703		3 = 270 degree rotation
1704
1705		If CONFIG_LCD_ROTATION is not defined, the console will be
1706		initialized with 0degree rotation.
1707
1708		CONFIG_LCD_BMP_RLE8
1709
1710		Support drawing of RLE8-compressed bitmaps on the LCD.
1711
1712		CONFIG_I2C_EDID
1713
1714		Enables an 'i2c edid' command which can read EDID
1715		information over I2C from an attached LCD display.
1716
1717- Splash Screen Support: CONFIG_SPLASH_SCREEN
1718
1719		If this option is set, the environment is checked for
1720		a variable "splashimage". If found, the usual display
1721		of logo, copyright and system information on the LCD
1722		is suppressed and the BMP image at the address
1723		specified in "splashimage" is loaded instead. The
1724		console is redirected to the "nulldev", too. This
1725		allows for a "silent" boot where a splash screen is
1726		loaded very quickly after power-on.
1727
1728		CONFIG_SPLASHIMAGE_GUARD
1729
1730		If this option is set, then U-Boot will prevent the environment
1731		variable "splashimage" from being set to a problematic address
1732		(see doc/README.displaying-bmps).
1733		This option is useful for targets where, due to alignment
1734		restrictions, an improperly aligned BMP image will cause a data
1735		abort. If you think you will not have problems with unaligned
1736		accesses (for example because your toolchain prevents them)
1737		there is no need to set this option.
1738
1739		CONFIG_SPLASH_SCREEN_ALIGN
1740
1741		If this option is set the splash image can be freely positioned
1742		on the screen. Environment variable "splashpos" specifies the
1743		position as "x,y". If a positive number is given it is used as
1744		number of pixel from left/top. If a negative number is given it
1745		is used as number of pixel from right/bottom. You can also
1746		specify 'm' for centering the image.
1747
1748		Example:
1749		setenv splashpos m,m
1750			=> image at center of screen
1751
1752		setenv splashpos 30,20
1753			=> image at x = 30 and y = 20
1754
1755		setenv splashpos -10,m
1756			=> vertically centered image
1757			   at x = dspWidth - bmpWidth - 9
1758
1759- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1760
1761		If this option is set, additionally to standard BMP
1762		images, gzipped BMP images can be displayed via the
1763		splashscreen support or the bmp command.
1764
1765- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1766
1767		If this option is set, 8-bit RLE compressed BMP images
1768		can be displayed via the splashscreen support or the
1769		bmp command.
1770
1771- Do compressing for memory range:
1772		CONFIG_CMD_ZIP
1773
1774		If this option is set, it would use zlib deflate method
1775		to compress the specified memory at its best effort.
1776
1777- Compression support:
1778		CONFIG_GZIP
1779
1780		Enabled by default to support gzip compressed images.
1781
1782		CONFIG_BZIP2
1783
1784		If this option is set, support for bzip2 compressed
1785		images is included. If not, only uncompressed and gzip
1786		compressed images are supported.
1787
1788		NOTE: the bzip2 algorithm requires a lot of RAM, so
1789		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1790		be at least 4MB.
1791
1792		CONFIG_LZMA
1793
1794		If this option is set, support for lzma compressed
1795		images is included.
1796
1797		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1798		requires an amount of dynamic memory that is given by the
1799		formula:
1800
1801			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1802
1803		Where lc and lp stand for, respectively, Literal context bits
1804		and Literal pos bits.
1805
1806		This value is upper-bounded by 14MB in the worst case. Anyway,
1807		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1808		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1809		a very small buffer.
1810
1811		Use the lzmainfo tool to determinate the lc and lp values and
1812		then calculate the amount of needed dynamic memory (ensuring
1813		the appropriate CONFIG_SYS_MALLOC_LEN value).
1814
1815		CONFIG_LZO
1816
1817		If this option is set, support for LZO compressed images
1818		is included.
1819
1820- MII/PHY support:
1821		CONFIG_PHY_ADDR
1822
1823		The address of PHY on MII bus.
1824
1825		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1826
1827		The clock frequency of the MII bus
1828
1829		CONFIG_PHY_GIGE
1830
1831		If this option is set, support for speed/duplex
1832		detection of gigabit PHY is included.
1833
1834		CONFIG_PHY_RESET_DELAY
1835
1836		Some PHY like Intel LXT971A need extra delay after
1837		reset before any MII register access is possible.
1838		For such PHY, set this option to the usec delay
1839		required. (minimum 300usec for LXT971A)
1840
1841		CONFIG_PHY_CMD_DELAY (ppc4xx)
1842
1843		Some PHY like Intel LXT971A need extra delay after
1844		command issued before MII status register can be read
1845
1846- IP address:
1847		CONFIG_IPADDR
1848
1849		Define a default value for the IP address to use for
1850		the default Ethernet interface, in case this is not
1851		determined through e.g. bootp.
1852		(Environment variable "ipaddr")
1853
1854- Server IP address:
1855		CONFIG_SERVERIP
1856
1857		Defines a default value for the IP address of a TFTP
1858		server to contact when using the "tftboot" command.
1859		(Environment variable "serverip")
1860
1861		CONFIG_KEEP_SERVERADDR
1862
1863		Keeps the server's MAC address, in the env 'serveraddr'
1864		for passing to bootargs (like Linux's netconsole option)
1865
1866- Gateway IP address:
1867		CONFIG_GATEWAYIP
1868
1869		Defines a default value for the IP address of the
1870		default router where packets to other networks are
1871		sent to.
1872		(Environment variable "gatewayip")
1873
1874- Subnet mask:
1875		CONFIG_NETMASK
1876
1877		Defines a default value for the subnet mask (or
1878		routing prefix) which is used to determine if an IP
1879		address belongs to the local subnet or needs to be
1880		forwarded through a router.
1881		(Environment variable "netmask")
1882
1883- Multicast TFTP Mode:
1884		CONFIG_MCAST_TFTP
1885
1886		Defines whether you want to support multicast TFTP as per
1887		rfc-2090; for example to work with atftp.  Lets lots of targets
1888		tftp down the same boot image concurrently.  Note: the Ethernet
1889		driver in use must provide a function: mcast() to join/leave a
1890		multicast group.
1891
1892- BOOTP Recovery Mode:
1893		CONFIG_BOOTP_RANDOM_DELAY
1894
1895		If you have many targets in a network that try to
1896		boot using BOOTP, you may want to avoid that all
1897		systems send out BOOTP requests at precisely the same
1898		moment (which would happen for instance at recovery
1899		from a power failure, when all systems will try to
1900		boot, thus flooding the BOOTP server. Defining
1901		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1902		inserted before sending out BOOTP requests. The
1903		following delays are inserted then:
1904
1905		1st BOOTP request:	delay 0 ... 1 sec
1906		2nd BOOTP request:	delay 0 ... 2 sec
1907		3rd BOOTP request:	delay 0 ... 4 sec
1908		4th and following
1909		BOOTP requests:		delay 0 ... 8 sec
1910
1911		CONFIG_BOOTP_ID_CACHE_SIZE
1912
1913		BOOTP packets are uniquely identified using a 32-bit ID. The
1914		server will copy the ID from client requests to responses and
1915		U-Boot will use this to determine if it is the destination of
1916		an incoming response. Some servers will check that addresses
1917		aren't in use before handing them out (usually using an ARP
1918		ping) and therefore take up to a few hundred milliseconds to
1919		respond. Network congestion may also influence the time it
1920		takes for a response to make it back to the client. If that
1921		time is too long, U-Boot will retransmit requests. In order
1922		to allow earlier responses to still be accepted after these
1923		retransmissions, U-Boot's BOOTP client keeps a small cache of
1924		IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1925		cache. The default is to keep IDs for up to four outstanding
1926		requests. Increasing this will allow U-Boot to accept offers
1927		from a BOOTP client in networks with unusually high latency.
1928
1929- DHCP Advanced Options:
1930		You can fine tune the DHCP functionality by defining
1931		CONFIG_BOOTP_* symbols:
1932
1933		CONFIG_BOOTP_SUBNETMASK
1934		CONFIG_BOOTP_GATEWAY
1935		CONFIG_BOOTP_HOSTNAME
1936		CONFIG_BOOTP_NISDOMAIN
1937		CONFIG_BOOTP_BOOTPATH
1938		CONFIG_BOOTP_BOOTFILESIZE
1939		CONFIG_BOOTP_DNS
1940		CONFIG_BOOTP_DNS2
1941		CONFIG_BOOTP_SEND_HOSTNAME
1942		CONFIG_BOOTP_NTPSERVER
1943		CONFIG_BOOTP_TIMEOFFSET
1944		CONFIG_BOOTP_VENDOREX
1945		CONFIG_BOOTP_MAY_FAIL
1946
1947		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1948		environment variable, not the BOOTP server.
1949
1950		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1951		after the configured retry count, the call will fail
1952		instead of starting over.  This can be used to fail over
1953		to Link-local IP address configuration if the DHCP server
1954		is not available.
1955
1956		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1957		serverip from a DHCP server, it is possible that more
1958		than one DNS serverip is offered to the client.
1959		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1960		serverip will be stored in the additional environment
1961		variable "dnsip2". The first DNS serverip is always
1962		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1963		is defined.
1964
1965		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1966		to do a dynamic update of a DNS server. To do this, they
1967		need the hostname of the DHCP requester.
1968		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1969		of the "hostname" environment variable is passed as
1970		option 12 to the DHCP server.
1971
1972		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1973
1974		A 32bit value in microseconds for a delay between
1975		receiving a "DHCP Offer" and sending the "DHCP Request".
1976		This fixes a problem with certain DHCP servers that don't
1977		respond 100% of the time to a "DHCP request". E.g. On an
1978		AT91RM9200 processor running at 180MHz, this delay needed
1979		to be *at least* 15,000 usec before a Windows Server 2003
1980		DHCP server would reply 100% of the time. I recommend at
1981		least 50,000 usec to be safe. The alternative is to hope
1982		that one of the retries will be successful but note that
1983		the DHCP timeout and retry process takes a longer than
1984		this delay.
1985
1986 - Link-local IP address negotiation:
1987		Negotiate with other link-local clients on the local network
1988		for an address that doesn't require explicit configuration.
1989		This is especially useful if a DHCP server cannot be guaranteed
1990		to exist in all environments that the device must operate.
1991
1992		See doc/README.link-local for more information.
1993
1994 - CDP Options:
1995		CONFIG_CDP_DEVICE_ID
1996
1997		The device id used in CDP trigger frames.
1998
1999		CONFIG_CDP_DEVICE_ID_PREFIX
2000
2001		A two character string which is prefixed to the MAC address
2002		of the device.
2003
2004		CONFIG_CDP_PORT_ID
2005
2006		A printf format string which contains the ascii name of
2007		the port. Normally is set to "eth%d" which sets
2008		eth0 for the first Ethernet, eth1 for the second etc.
2009
2010		CONFIG_CDP_CAPABILITIES
2011
2012		A 32bit integer which indicates the device capabilities;
2013		0x00000010 for a normal host which does not forwards.
2014
2015		CONFIG_CDP_VERSION
2016
2017		An ascii string containing the version of the software.
2018
2019		CONFIG_CDP_PLATFORM
2020
2021		An ascii string containing the name of the platform.
2022
2023		CONFIG_CDP_TRIGGER
2024
2025		A 32bit integer sent on the trigger.
2026
2027		CONFIG_CDP_POWER_CONSUMPTION
2028
2029		A 16bit integer containing the power consumption of the
2030		device in .1 of milliwatts.
2031
2032		CONFIG_CDP_APPLIANCE_VLAN_TYPE
2033
2034		A byte containing the id of the VLAN.
2035
2036- Status LED:	CONFIG_STATUS_LED
2037
2038		Several configurations allow to display the current
2039		status using a LED. For instance, the LED will blink
2040		fast while running U-Boot code, stop blinking as
2041		soon as a reply to a BOOTP request was received, and
2042		start blinking slow once the Linux kernel is running
2043		(supported by a status LED driver in the Linux
2044		kernel). Defining CONFIG_STATUS_LED enables this
2045		feature in U-Boot.
2046
2047		Additional options:
2048
2049		CONFIG_GPIO_LED
2050		The status LED can be connected to a GPIO pin.
2051		In such cases, the gpio_led driver can be used as a
2052		status LED backend implementation. Define CONFIG_GPIO_LED
2053		to include the gpio_led driver in the U-Boot binary.
2054
2055		CONFIG_GPIO_LED_INVERTED_TABLE
2056		Some GPIO connected LEDs may have inverted polarity in which
2057		case the GPIO high value corresponds to LED off state and
2058		GPIO low value corresponds to LED on state.
2059		In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
2060		with a list of GPIO LEDs that have inverted polarity.
2061
2062- CAN Support:	CONFIG_CAN_DRIVER
2063
2064		Defining CONFIG_CAN_DRIVER enables CAN driver support
2065		on those systems that support this (optional)
2066		feature, like the TQM8xxL modules.
2067
2068- I2C Support:	CONFIG_SYS_I2C
2069
2070		This enable the NEW i2c subsystem, and will allow you to use
2071		i2c commands at the u-boot command line (as long as you set
2072		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
2073		based realtime clock chips or other i2c devices. See
2074		common/cmd_i2c.c for a description of the command line
2075		interface.
2076
2077		ported i2c driver to the new framework:
2078		- drivers/i2c/soft_i2c.c:
2079		  - activate first bus with CONFIG_SYS_I2C_SOFT define
2080		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
2081		    for defining speed and slave address
2082		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
2083		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
2084		    for defining speed and slave address
2085		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
2086		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
2087		    for defining speed and slave address
2088		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
2089		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
2090		    for defining speed and slave address
2091
2092		- drivers/i2c/fsl_i2c.c:
2093		  - activate i2c driver with CONFIG_SYS_I2C_FSL
2094		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
2095		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
2096		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
2097		    bus.
2098		  - If your board supports a second fsl i2c bus, define
2099		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
2100		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
2101		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
2102		    second bus.
2103
2104		- drivers/i2c/tegra_i2c.c:
2105		  - activate this driver with CONFIG_SYS_I2C_TEGRA
2106		  - This driver adds 4 i2c buses with a fix speed from
2107		    100000 and the slave addr 0!
2108
2109		- drivers/i2c/ppc4xx_i2c.c
2110		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
2111		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
2112		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
2113
2114		- drivers/i2c/i2c_mxc.c
2115		  - activate this driver with CONFIG_SYS_I2C_MXC
2116		  - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1
2117		  - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2
2118		  - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3
2119		  - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4
2120		  - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
2121		  - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
2122		  - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
2123		  - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
2124		  - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
2125		  - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
2126		  - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED
2127		  - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE
2128		If those defines are not set, default value is 100000
2129		for speed, and 0 for slave.
2130
2131		- drivers/i2c/rcar_i2c.c:
2132		  - activate this driver with CONFIG_SYS_I2C_RCAR
2133		  - This driver adds 4 i2c buses
2134
2135		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
2136		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
2137		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
2138		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
2139		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
2140		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
2141		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
2142		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
2143		  - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
2144
2145		- drivers/i2c/sh_i2c.c:
2146		  - activate this driver with CONFIG_SYS_I2C_SH
2147		  - This driver adds from 2 to 5 i2c buses
2148
2149		  - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
2150		  - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
2151		  - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
2152		  - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
2153		  - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
2154		  - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
2155		  - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
2156		  - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
2157		  - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
2158		  - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
2159		  - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses
2160
2161		- drivers/i2c/omap24xx_i2c.c
2162		  - activate this driver with CONFIG_SYS_I2C_OMAP24XX
2163		  - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
2164		  - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
2165		  - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
2166		  - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
2167		  - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
2168		  - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
2169		  - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
2170		  - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
2171		  - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
2172		  - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
2173
2174		- drivers/i2c/zynq_i2c.c
2175		  - activate this driver with CONFIG_SYS_I2C_ZYNQ
2176		  - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
2177		  - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
2178
2179		- drivers/i2c/s3c24x0_i2c.c:
2180		  - activate this driver with CONFIG_SYS_I2C_S3C24X0
2181		  - This driver adds i2c buses (11 for Exynos5250, Exynos5420
2182		    9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
2183		    with a fix speed from 100000 and the slave addr 0!
2184
2185		- drivers/i2c/ihs_i2c.c
2186		  - activate this driver with CONFIG_SYS_I2C_IHS
2187		  - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
2188		  - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
2189		  - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
2190		  - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
2191		  - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
2192		  - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
2193		  - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
2194		  - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
2195		  - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
2196		  - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
2197		  - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
2198		  - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3
2199		  - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL
2200		  - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1
2201		  - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1
2202		  - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1
2203		  - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1
2204		  - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1
2205		  - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1
2206		  - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1
2207		  - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1
2208
2209		additional defines:
2210
2211		CONFIG_SYS_NUM_I2C_BUSES
2212		Hold the number of i2c buses you want to use.
2213
2214		CONFIG_SYS_I2C_DIRECT_BUS
2215		define this, if you don't use i2c muxes on your hardware.
2216		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2217		omit this define.
2218
2219		CONFIG_SYS_I2C_MAX_HOPS
2220		define how many muxes are maximal consecutively connected
2221		on one i2c bus. If you not use i2c muxes, omit this
2222		define.
2223
2224		CONFIG_SYS_I2C_BUSES
2225		hold a list of buses you want to use, only used if
2226		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2227		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2228		CONFIG_SYS_NUM_I2C_BUSES = 9:
2229
2230		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
2231					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2232					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2233					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2234					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2235					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2236					{1, {I2C_NULL_HOP}}, \
2237					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2238					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2239					}
2240
2241		which defines
2242			bus 0 on adapter 0 without a mux
2243			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2244			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2245			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2246			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2247			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2248			bus 6 on adapter 1 without a mux
2249			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2250			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2251
2252		If you do not have i2c muxes on your board, omit this define.
2253
2254- Legacy I2C Support:	CONFIG_HARD_I2C
2255
2256		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2257		provides the following compelling advantages:
2258
2259		- more than one i2c adapter is usable
2260		- approved multibus support
2261		- better i2c mux support
2262
2263		** Please consider updating your I2C driver now. **
2264
2265		These enable legacy I2C serial bus commands. Defining
2266		CONFIG_HARD_I2C will include the appropriate I2C driver
2267		for the selected CPU.
2268
2269		This will allow you to use i2c commands at the u-boot
2270		command line (as long as you set CONFIG_CMD_I2C in
2271		CONFIG_COMMANDS) and communicate with i2c based realtime
2272		clock chips. See common/cmd_i2c.c for a description of the
2273		command line interface.
2274
2275		CONFIG_HARD_I2C selects a hardware I2C controller.
2276
2277		There are several other quantities that must also be
2278		defined when you define CONFIG_HARD_I2C.
2279
2280		In both cases you will need to define CONFIG_SYS_I2C_SPEED
2281		to be the frequency (in Hz) at which you wish your i2c bus
2282		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2283		the CPU's i2c node address).
2284
2285		Now, the u-boot i2c code for the mpc8xx
2286		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2287		and so its address should therefore be cleared to 0 (See,
2288		eg, MPC823e User's Manual p.16-473). So, set
2289		CONFIG_SYS_I2C_SLAVE to 0.
2290
2291		CONFIG_SYS_I2C_INIT_MPC5XXX
2292
2293		When a board is reset during an i2c bus transfer
2294		chips might think that the current transfer is still
2295		in progress.  Reset the slave devices by sending start
2296		commands until the slave device responds.
2297
2298		That's all that's required for CONFIG_HARD_I2C.
2299
2300		If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2301		then the following macros need to be defined (examples are
2302		from include/configs/lwmon.h):
2303
2304		I2C_INIT
2305
2306		(Optional). Any commands necessary to enable the I2C
2307		controller or configure ports.
2308
2309		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2310
2311		I2C_PORT
2312
2313		(Only for MPC8260 CPU). The I/O port to use (the code
2314		assumes both bits are on the same port). Valid values
2315		are 0..3 for ports A..D.
2316
2317		I2C_ACTIVE
2318
2319		The code necessary to make the I2C data line active
2320		(driven).  If the data line is open collector, this
2321		define can be null.
2322
2323		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2324
2325		I2C_TRISTATE
2326
2327		The code necessary to make the I2C data line tri-stated
2328		(inactive).  If the data line is open collector, this
2329		define can be null.
2330
2331		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2332
2333		I2C_READ
2334
2335		Code that returns true if the I2C data line is high,
2336		false if it is low.
2337
2338		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2339
2340		I2C_SDA(bit)
2341
2342		If <bit> is true, sets the I2C data line high. If it
2343		is false, it clears it (low).
2344
2345		eg: #define I2C_SDA(bit) \
2346			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2347			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2348
2349		I2C_SCL(bit)
2350
2351		If <bit> is true, sets the I2C clock line high. If it
2352		is false, it clears it (low).
2353
2354		eg: #define I2C_SCL(bit) \
2355			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2356			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2357
2358		I2C_DELAY
2359
2360		This delay is invoked four times per clock cycle so this
2361		controls the rate of data transfer.  The data rate thus
2362		is 1 / (I2C_DELAY * 4). Often defined to be something
2363		like:
2364
2365		#define I2C_DELAY  udelay(2)
2366
2367		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2368
2369		If your arch supports the generic GPIO framework (asm/gpio.h),
2370		then you may alternatively define the two GPIOs that are to be
2371		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2372		have GPIO-based defaults assigned to them as appropriate.
2373
2374		You should define these to the GPIO value as given directly to
2375		the generic GPIO functions.
2376
2377		CONFIG_SYS_I2C_INIT_BOARD
2378
2379		When a board is reset during an i2c bus transfer
2380		chips might think that the current transfer is still
2381		in progress. On some boards it is possible to access
2382		the i2c SCLK line directly, either by using the
2383		processor pin as a GPIO or by having a second pin
2384		connected to the bus. If this option is defined a
2385		custom i2c_init_board() routine in boards/xxx/board.c
2386		is run early in the boot sequence.
2387
2388		CONFIG_SYS_I2C_BOARD_LATE_INIT
2389
2390		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2391		defined a custom i2c_board_late_init() routine in
2392		boards/xxx/board.c is run AFTER the operations in i2c_init()
2393		is completed. This callpoint can be used to unreset i2c bus
2394		using CPU i2c controller register accesses for CPUs whose i2c
2395		controller provide such a method. It is called at the end of
2396		i2c_init() to allow i2c_init operations to setup the i2c bus
2397		controller on the CPU (e.g. setting bus speed & slave address).
2398
2399		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2400
2401		This option enables configuration of bi_iic_fast[] flags
2402		in u-boot bd_info structure based on u-boot environment
2403		variable "i2cfast". (see also i2cfast)
2404
2405		CONFIG_I2C_MULTI_BUS
2406
2407		This option allows the use of multiple I2C buses, each of which
2408		must have a controller.	 At any point in time, only one bus is
2409		active.	 To switch to a different bus, use the 'i2c dev' command.
2410		Note that bus numbering is zero-based.
2411
2412		CONFIG_SYS_I2C_NOPROBES
2413
2414		This option specifies a list of I2C devices that will be skipped
2415		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2416		is set, specify a list of bus-device pairs.  Otherwise, specify
2417		a 1D array of device addresses
2418
2419		e.g.
2420			#undef	CONFIG_I2C_MULTI_BUS
2421			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2422
2423		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2424
2425			#define CONFIG_I2C_MULTI_BUS
2426			#define CONFIG_SYS_I2C_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2427
2428		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2429
2430		CONFIG_SYS_SPD_BUS_NUM
2431
2432		If defined, then this indicates the I2C bus number for DDR SPD.
2433		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2434
2435		CONFIG_SYS_RTC_BUS_NUM
2436
2437		If defined, then this indicates the I2C bus number for the RTC.
2438		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2439
2440		CONFIG_SYS_DTT_BUS_NUM
2441
2442		If defined, then this indicates the I2C bus number for the DTT.
2443		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2444
2445		CONFIG_SYS_I2C_DTT_ADDR:
2446
2447		If defined, specifies the I2C address of the DTT device.
2448		If not defined, then U-Boot uses predefined value for
2449		specified DTT device.
2450
2451		CONFIG_SOFT_I2C_READ_REPEATED_START
2452
2453		defining this will force the i2c_read() function in
2454		the soft_i2c driver to perform an I2C repeated start
2455		between writing the address pointer and reading the
2456		data.  If this define is omitted the default behaviour
2457		of doing a stop-start sequence will be used.  Most I2C
2458		devices can use either method, but some require one or
2459		the other.
2460
2461- SPI Support:	CONFIG_SPI
2462
2463		Enables SPI driver (so far only tested with
2464		SPI EEPROM, also an instance works with Crystal A/D and
2465		D/As on the SACSng board)
2466
2467		CONFIG_SH_SPI
2468
2469		Enables the driver for SPI controller on SuperH. Currently
2470		only SH7757 is supported.
2471
2472		CONFIG_SOFT_SPI
2473
2474		Enables a software (bit-bang) SPI driver rather than
2475		using hardware support. This is a general purpose
2476		driver that only requires three general I/O port pins
2477		(two outputs, one input) to function. If this is
2478		defined, the board configuration must define several
2479		SPI configuration items (port pins to use, etc). For
2480		an example, see include/configs/sacsng.h.
2481
2482		CONFIG_HARD_SPI
2483
2484		Enables a hardware SPI driver for general-purpose reads
2485		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2486		must define a list of chip-select function pointers.
2487		Currently supported on some MPC8xxx processors.	 For an
2488		example, see include/configs/mpc8349emds.h.
2489
2490		CONFIG_MXC_SPI
2491
2492		Enables the driver for the SPI controllers on i.MX and MXC
2493		SoCs. Currently i.MX31/35/51 are supported.
2494
2495		CONFIG_SYS_SPI_MXC_WAIT
2496		Timeout for waiting until spi transfer completed.
2497		default: (CONFIG_SYS_HZ/100)     /* 10 ms */
2498
2499- FPGA Support: CONFIG_FPGA
2500
2501		Enables FPGA subsystem.
2502
2503		CONFIG_FPGA_<vendor>
2504
2505		Enables support for specific chip vendors.
2506		(ALTERA, XILINX)
2507
2508		CONFIG_FPGA_<family>
2509
2510		Enables support for FPGA family.
2511		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2512
2513		CONFIG_FPGA_COUNT
2514
2515		Specify the number of FPGA devices to support.
2516
2517		CONFIG_CMD_FPGA_LOADMK
2518
2519		Enable support for fpga loadmk command
2520
2521		CONFIG_CMD_FPGA_LOADP
2522
2523		Enable support for fpga loadp command - load partial bitstream
2524
2525		CONFIG_CMD_FPGA_LOADBP
2526
2527		Enable support for fpga loadbp command - load partial bitstream
2528		(Xilinx only)
2529
2530		CONFIG_SYS_FPGA_PROG_FEEDBACK
2531
2532		Enable printing of hash marks during FPGA configuration.
2533
2534		CONFIG_SYS_FPGA_CHECK_BUSY
2535
2536		Enable checks on FPGA configuration interface busy
2537		status by the configuration function. This option
2538		will require a board or device specific function to
2539		be written.
2540
2541		CONFIG_FPGA_DELAY
2542
2543		If defined, a function that provides delays in the FPGA
2544		configuration driver.
2545
2546		CONFIG_SYS_FPGA_CHECK_CTRLC
2547		Allow Control-C to interrupt FPGA configuration
2548
2549		CONFIG_SYS_FPGA_CHECK_ERROR
2550
2551		Check for configuration errors during FPGA bitfile
2552		loading. For example, abort during Virtex II
2553		configuration if the INIT_B line goes low (which
2554		indicated a CRC error).
2555
2556		CONFIG_SYS_FPGA_WAIT_INIT
2557
2558		Maximum time to wait for the INIT_B line to de-assert
2559		after PROB_B has been de-asserted during a Virtex II
2560		FPGA configuration sequence. The default time is 500
2561		ms.
2562
2563		CONFIG_SYS_FPGA_WAIT_BUSY
2564
2565		Maximum time to wait for BUSY to de-assert during
2566		Virtex II FPGA configuration. The default is 5 ms.
2567
2568		CONFIG_SYS_FPGA_WAIT_CONFIG
2569
2570		Time to wait after FPGA configuration. The default is
2571		200 ms.
2572
2573- Configuration Management:
2574		CONFIG_BUILD_TARGET
2575
2576		Some SoCs need special image types (e.g. U-Boot binary
2577		with a special header) as build targets. By defining
2578		CONFIG_BUILD_TARGET in the SoC / board header, this
2579		special image will be automatically built upon calling
2580		make / buildman.
2581
2582		CONFIG_IDENT_STRING
2583
2584		If defined, this string will be added to the U-Boot
2585		version information (U_BOOT_VERSION)
2586
2587- Vendor Parameter Protection:
2588
2589		U-Boot considers the values of the environment
2590		variables "serial#" (Board Serial Number) and
2591		"ethaddr" (Ethernet Address) to be parameters that
2592		are set once by the board vendor / manufacturer, and
2593		protects these variables from casual modification by
2594		the user. Once set, these variables are read-only,
2595		and write or delete attempts are rejected. You can
2596		change this behaviour:
2597
2598		If CONFIG_ENV_OVERWRITE is #defined in your config
2599		file, the write protection for vendor parameters is
2600		completely disabled. Anybody can change or delete
2601		these parameters.
2602
2603		Alternatively, if you define _both_ an ethaddr in the
2604		default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2605		Ethernet address is installed in the environment,
2606		which can be changed exactly ONCE by the user. [The
2607		serial# is unaffected by this, i. e. it remains
2608		read-only.]
2609
2610		The same can be accomplished in a more flexible way
2611		for any variable by configuring the type of access
2612		to allow for those variables in the ".flags" variable
2613		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2614
2615- Protected RAM:
2616		CONFIG_PRAM
2617
2618		Define this variable to enable the reservation of
2619		"protected RAM", i. e. RAM which is not overwritten
2620		by U-Boot. Define CONFIG_PRAM to hold the number of
2621		kB you want to reserve for pRAM. You can overwrite
2622		this default value by defining an environment
2623		variable "pram" to the number of kB you want to
2624		reserve. Note that the board info structure will
2625		still show the full amount of RAM. If pRAM is
2626		reserved, a new environment variable "mem" will
2627		automatically be defined to hold the amount of
2628		remaining RAM in a form that can be passed as boot
2629		argument to Linux, for instance like that:
2630
2631			setenv bootargs ... mem=\${mem}
2632			saveenv
2633
2634		This way you can tell Linux not to use this memory,
2635		either, which results in a memory region that will
2636		not be affected by reboots.
2637
2638		*WARNING* If your board configuration uses automatic
2639		detection of the RAM size, you must make sure that
2640		this memory test is non-destructive. So far, the
2641		following board configurations are known to be
2642		"pRAM-clean":
2643
2644			IVMS8, IVML24, SPD8xx, TQM8xxL,
2645			HERMES, IP860, RPXlite, LWMON,
2646			FLAGADM, TQM8260
2647
2648- Access to physical memory region (> 4GB)
2649		Some basic support is provided for operations on memory not
2650		normally accessible to U-Boot - e.g. some architectures
2651		support access to more than 4GB of memory on 32-bit
2652		machines using physical address extension or similar.
2653		Define CONFIG_PHYSMEM to access this basic support, which
2654		currently only supports clearing the memory.
2655
2656- Error Recovery:
2657		CONFIG_PANIC_HANG
2658
2659		Define this variable to stop the system in case of a
2660		fatal error, so that you have to reset it manually.
2661		This is probably NOT a good idea for an embedded
2662		system where you want the system to reboot
2663		automatically as fast as possible, but it may be
2664		useful during development since you can try to debug
2665		the conditions that lead to the situation.
2666
2667		CONFIG_NET_RETRY_COUNT
2668
2669		This variable defines the number of retries for
2670		network operations like ARP, RARP, TFTP, or BOOTP
2671		before giving up the operation. If not defined, a
2672		default value of 5 is used.
2673
2674		CONFIG_ARP_TIMEOUT
2675
2676		Timeout waiting for an ARP reply in milliseconds.
2677
2678		CONFIG_NFS_TIMEOUT
2679
2680		Timeout in milliseconds used in NFS protocol.
2681		If you encounter "ERROR: Cannot umount" in nfs command,
2682		try longer timeout such as
2683		#define CONFIG_NFS_TIMEOUT 10000UL
2684
2685- Command Interpreter:
2686		CONFIG_AUTO_COMPLETE
2687
2688		Enable auto completion of commands using TAB.
2689
2690		CONFIG_SYS_PROMPT_HUSH_PS2
2691
2692		This defines the secondary prompt string, which is
2693		printed when the command interpreter needs more input
2694		to complete a command. Usually "> ".
2695
2696	Note:
2697
2698		In the current implementation, the local variables
2699		space and global environment variables space are
2700		separated. Local variables are those you define by
2701		simply typing `name=value'. To access a local
2702		variable later on, you have write `$name' or
2703		`${name}'; to execute the contents of a variable
2704		directly type `$name' at the command prompt.
2705
2706		Global environment variables are those you use
2707		setenv/printenv to work with. To run a command stored
2708		in such a variable, you need to use the run command,
2709		and you must not use the '$' sign to access them.
2710
2711		To store commands and special characters in a
2712		variable, please use double quotation marks
2713		surrounding the whole text of the variable, instead
2714		of the backslashes before semicolons and special
2715		symbols.
2716
2717- Command Line Editing and History:
2718		CONFIG_CMDLINE_EDITING
2719
2720		Enable editing and History functions for interactive
2721		command line input operations
2722
2723- Command Line PS1/PS2 support:
2724		CONFIG_CMDLINE_PS_SUPPORT
2725
2726		Enable support for changing the command prompt string
2727		at run-time. Only static string is supported so far.
2728		The string is obtained from environment variables PS1
2729		and PS2.
2730
2731- Default Environment:
2732		CONFIG_EXTRA_ENV_SETTINGS
2733
2734		Define this to contain any number of null terminated
2735		strings (variable = value pairs) that will be part of
2736		the default environment compiled into the boot image.
2737
2738		For example, place something like this in your
2739		board's config file:
2740
2741		#define CONFIG_EXTRA_ENV_SETTINGS \
2742			"myvar1=value1\0" \
2743			"myvar2=value2\0"
2744
2745		Warning: This method is based on knowledge about the
2746		internal format how the environment is stored by the
2747		U-Boot code. This is NOT an official, exported
2748		interface! Although it is unlikely that this format
2749		will change soon, there is no guarantee either.
2750		You better know what you are doing here.
2751
2752		Note: overly (ab)use of the default environment is
2753		discouraged. Make sure to check other ways to preset
2754		the environment like the "source" command or the
2755		boot command first.
2756
2757		CONFIG_ENV_VARS_UBOOT_CONFIG
2758
2759		Define this in order to add variables describing the
2760		U-Boot build configuration to the default environment.
2761		These will be named arch, cpu, board, vendor, and soc.
2762
2763		Enabling this option will cause the following to be defined:
2764
2765		- CONFIG_SYS_ARCH
2766		- CONFIG_SYS_CPU
2767		- CONFIG_SYS_BOARD
2768		- CONFIG_SYS_VENDOR
2769		- CONFIG_SYS_SOC
2770
2771		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2772
2773		Define this in order to add variables describing certain
2774		run-time determined information about the hardware to the
2775		environment.  These will be named board_name, board_rev.
2776
2777		CONFIG_DELAY_ENVIRONMENT
2778
2779		Normally the environment is loaded when the board is
2780		initialised so that it is available to U-Boot. This inhibits
2781		that so that the environment is not available until
2782		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2783		this is instead controlled by the value of
2784		/config/load-environment.
2785
2786- Parallel Flash support:
2787		CONFIG_SYS_NO_FLASH
2788
2789		Traditionally U-Boot was run on systems with parallel NOR
2790		flash. This option is used to disable support for parallel NOR
2791		flash. This option should be defined if the board does not have
2792		parallel flash.
2793
2794		If this option is not defined one of the generic flash drivers
2795		(e.g.  CONFIG_FLASH_CFI_DRIVER or CONFIG_ST_SMI) must be
2796		selected or the board must provide an implementation of the
2797		flash API (see include/flash.h).
2798
2799- DataFlash Support:
2800		CONFIG_HAS_DATAFLASH
2801
2802		Defining this option enables DataFlash features and
2803		allows to read/write in Dataflash via the standard
2804		commands cp, md...
2805
2806- Serial Flash support
2807		CONFIG_CMD_SF
2808
2809		Defining this option enables SPI flash commands
2810		'sf probe/read/write/erase/update'.
2811
2812		Usage requires an initial 'probe' to define the serial
2813		flash parameters, followed by read/write/erase/update
2814		commands.
2815
2816		The following defaults may be provided by the platform
2817		to handle the common case when only a single serial
2818		flash is present on the system.
2819
2820		CONFIG_SF_DEFAULT_BUS		Bus identifier
2821		CONFIG_SF_DEFAULT_CS		Chip-select
2822		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2823		CONFIG_SF_DEFAULT_SPEED		in Hz
2824
2825		CONFIG_CMD_SF_TEST
2826
2827		Define this option to include a destructive SPI flash
2828		test ('sf test').
2829
2830		CONFIG_SF_DUAL_FLASH		Dual flash memories
2831
2832		Define this option to use dual flash support where two flash
2833		memories can be connected with a given cs line.
2834		Currently Xilinx Zynq qspi supports these type of connections.
2835
2836- SystemACE Support:
2837		CONFIG_SYSTEMACE
2838
2839		Adding this option adds support for Xilinx SystemACE
2840		chips attached via some sort of local bus. The address
2841		of the chip must also be defined in the
2842		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2843
2844		#define CONFIG_SYSTEMACE
2845		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2846
2847		When SystemACE support is added, the "ace" device type
2848		becomes available to the fat commands, i.e. fatls.
2849
2850- TFTP Fixed UDP Port:
2851		CONFIG_TFTP_PORT
2852
2853		If this is defined, the environment variable tftpsrcp
2854		is used to supply the TFTP UDP source port value.
2855		If tftpsrcp isn't defined, the normal pseudo-random port
2856		number generator is used.
2857
2858		Also, the environment variable tftpdstp is used to supply
2859		the TFTP UDP destination port value.  If tftpdstp isn't
2860		defined, the normal port 69 is used.
2861
2862		The purpose for tftpsrcp is to allow a TFTP server to
2863		blindly start the TFTP transfer using the pre-configured
2864		target IP address and UDP port. This has the effect of
2865		"punching through" the (Windows XP) firewall, allowing
2866		the remainder of the TFTP transfer to proceed normally.
2867		A better solution is to properly configure the firewall,
2868		but sometimes that is not allowed.
2869
2870- Hashing support:
2871		CONFIG_CMD_HASH
2872
2873		This enables a generic 'hash' command which can produce
2874		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
2875
2876		CONFIG_HASH_VERIFY
2877
2878		Enable the hash verify command (hash -v). This adds to code
2879		size a little.
2880
2881		CONFIG_SHA1 - This option enables support of hashing using SHA1
2882		algorithm. The hash is calculated in software.
2883		CONFIG_SHA256 - This option enables support of hashing using
2884		SHA256 algorithm. The hash is calculated in software.
2885		CONFIG_SHA_HW_ACCEL - This option enables hardware acceleration
2886		for SHA1/SHA256 hashing.
2887		This affects the 'hash' command and also the
2888		hash_lookup_algo() function.
2889		CONFIG_SHA_PROG_HW_ACCEL - This option enables
2890		hardware-acceleration for SHA1/SHA256 progressive hashing.
2891		Data can be streamed in a block at a time and the hashing
2892		is performed in hardware.
2893
2894		Note: There is also a sha1sum command, which should perhaps
2895		be deprecated in favour of 'hash sha1'.
2896
2897- Freescale i.MX specific commands:
2898		CONFIG_CMD_HDMIDETECT
2899		This enables 'hdmidet' command which returns true if an
2900		HDMI monitor is detected.  This command is i.MX 6 specific.
2901
2902		CONFIG_CMD_BMODE
2903		This enables the 'bmode' (bootmode) command for forcing
2904		a boot from specific media.
2905
2906		This is useful for forcing the ROM's usb downloader to
2907		activate upon a watchdog reset which is nice when iterating
2908		on U-Boot.  Using the reset button or running bmode normal
2909		will set it back to normal.  This command currently
2910		supports i.MX53 and i.MX6.
2911
2912- bootcount support:
2913		CONFIG_BOOTCOUNT_LIMIT
2914
2915		This enables the bootcounter support, see:
2916		http://www.denx.de/wiki/DULG/UBootBootCountLimit
2917
2918		CONFIG_AT91SAM9XE
2919		enable special bootcounter support on at91sam9xe based boards.
2920		CONFIG_BLACKFIN
2921		enable special bootcounter support on blackfin based boards.
2922		CONFIG_SOC_DA8XX
2923		enable special bootcounter support on da850 based boards.
2924		CONFIG_BOOTCOUNT_RAM
2925		enable support for the bootcounter in RAM
2926		CONFIG_BOOTCOUNT_I2C
2927		enable support for the bootcounter on an i2c (like RTC) device.
2928			CONFIG_SYS_I2C_RTC_ADDR = i2c chip address
2929			CONFIG_SYS_BOOTCOUNT_ADDR = i2c addr which is used for
2930						    the bootcounter.
2931			CONFIG_BOOTCOUNT_ALEN = address len
2932
2933- Show boot progress:
2934		CONFIG_SHOW_BOOT_PROGRESS
2935
2936		Defining this option allows to add some board-
2937		specific code (calling a user-provided function
2938		"show_boot_progress(int)") that enables you to show
2939		the system's boot progress on some display (for
2940		example, some LED's) on your board. At the moment,
2941		the following checkpoints are implemented:
2942
2943
2944Legacy uImage format:
2945
2946  Arg	Where			When
2947    1	common/cmd_bootm.c	before attempting to boot an image
2948   -1	common/cmd_bootm.c	Image header has bad	 magic number
2949    2	common/cmd_bootm.c	Image header has correct magic number
2950   -2	common/cmd_bootm.c	Image header has bad	 checksum
2951    3	common/cmd_bootm.c	Image header has correct checksum
2952   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2953    4	common/cmd_bootm.c	Image data   has correct checksum
2954   -4	common/cmd_bootm.c	Image is for unsupported architecture
2955    5	common/cmd_bootm.c	Architecture check OK
2956   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2957    6	common/cmd_bootm.c	Image Type check OK
2958   -6	common/cmd_bootm.c	gunzip uncompression error
2959   -7	common/cmd_bootm.c	Unimplemented compression type
2960    7	common/cmd_bootm.c	Uncompression OK
2961    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2962   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2963
2964    9	common/image.c		Start initial ramdisk verification
2965  -10	common/image.c		Ramdisk header has bad	   magic number
2966  -11	common/image.c		Ramdisk header has bad	   checksum
2967   10	common/image.c		Ramdisk header is OK
2968  -12	common/image.c		Ramdisk data   has bad	   checksum
2969   11	common/image.c		Ramdisk data   has correct checksum
2970   12	common/image.c		Ramdisk verification complete, start loading
2971  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2972   13	common/image.c		Start multifile image verification
2973   14	common/image.c		No initial ramdisk, no multifile, continue.
2974
2975   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2976
2977  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2978  -31	post/post.c		POST test failed, detected by post_output_backlog()
2979  -32	post/post.c		POST test failed, detected by post_run_single()
2980
2981   34	common/cmd_doc.c	before loading a Image from a DOC device
2982  -35	common/cmd_doc.c	Bad usage of "doc" command
2983   35	common/cmd_doc.c	correct usage of "doc" command
2984  -36	common/cmd_doc.c	No boot device
2985   36	common/cmd_doc.c	correct boot device
2986  -37	common/cmd_doc.c	Unknown Chip ID on boot device
2987   37	common/cmd_doc.c	correct chip ID found, device available
2988  -38	common/cmd_doc.c	Read Error on boot device
2989   38	common/cmd_doc.c	reading Image header from DOC device OK
2990  -39	common/cmd_doc.c	Image header has bad magic number
2991   39	common/cmd_doc.c	Image header has correct magic number
2992  -40	common/cmd_doc.c	Error reading Image from DOC device
2993   40	common/cmd_doc.c	Image header has correct magic number
2994   41	common/cmd_ide.c	before loading a Image from a IDE device
2995  -42	common/cmd_ide.c	Bad usage of "ide" command
2996   42	common/cmd_ide.c	correct usage of "ide" command
2997  -43	common/cmd_ide.c	No boot device
2998   43	common/cmd_ide.c	boot device found
2999  -44	common/cmd_ide.c	Device not available
3000   44	common/cmd_ide.c	Device available
3001  -45	common/cmd_ide.c	wrong partition selected
3002   45	common/cmd_ide.c	partition selected
3003  -46	common/cmd_ide.c	Unknown partition table
3004   46	common/cmd_ide.c	valid partition table found
3005  -47	common/cmd_ide.c	Invalid partition type
3006   47	common/cmd_ide.c	correct partition type
3007  -48	common/cmd_ide.c	Error reading Image Header on boot device
3008   48	common/cmd_ide.c	reading Image Header from IDE device OK
3009  -49	common/cmd_ide.c	Image header has bad magic number
3010   49	common/cmd_ide.c	Image header has correct magic number
3011  -50	common/cmd_ide.c	Image header has bad	 checksum
3012   50	common/cmd_ide.c	Image header has correct checksum
3013  -51	common/cmd_ide.c	Error reading Image from IDE device
3014   51	common/cmd_ide.c	reading Image from IDE device OK
3015   52	common/cmd_nand.c	before loading a Image from a NAND device
3016  -53	common/cmd_nand.c	Bad usage of "nand" command
3017   53	common/cmd_nand.c	correct usage of "nand" command
3018  -54	common/cmd_nand.c	No boot device
3019   54	common/cmd_nand.c	boot device found
3020  -55	common/cmd_nand.c	Unknown Chip ID on boot device
3021   55	common/cmd_nand.c	correct chip ID found, device available
3022  -56	common/cmd_nand.c	Error reading Image Header on boot device
3023   56	common/cmd_nand.c	reading Image Header from NAND device OK
3024  -57	common/cmd_nand.c	Image header has bad magic number
3025   57	common/cmd_nand.c	Image header has correct magic number
3026  -58	common/cmd_nand.c	Error reading Image from NAND device
3027   58	common/cmd_nand.c	reading Image from NAND device OK
3028
3029  -60	common/env_common.c	Environment has a bad CRC, using default
3030
3031   64	net/eth.c		starting with Ethernet configuration.
3032  -64	net/eth.c		no Ethernet found.
3033   65	net/eth.c		Ethernet found.
3034
3035  -80	common/cmd_net.c	usage wrong
3036   80	common/cmd_net.c	before calling net_loop()
3037  -81	common/cmd_net.c	some error in net_loop() occurred
3038   81	common/cmd_net.c	net_loop() back without error
3039  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
3040   82	common/cmd_net.c	trying automatic boot
3041   83	common/cmd_net.c	running "source" command
3042  -83	common/cmd_net.c	some error in automatic boot or "source" command
3043   84	common/cmd_net.c	end without errors
3044
3045FIT uImage format:
3046
3047  Arg	Where			When
3048  100	common/cmd_bootm.c	Kernel FIT Image has correct format
3049 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
3050  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
3051 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
3052  102	common/cmd_bootm.c	Kernel unit name specified
3053 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
3054  103	common/cmd_bootm.c	Found configuration node
3055  104	common/cmd_bootm.c	Got kernel subimage node offset
3056 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
3057  105	common/cmd_bootm.c	Kernel subimage hash verification OK
3058 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
3059  106	common/cmd_bootm.c	Architecture check OK
3060 -106	common/cmd_bootm.c	Kernel subimage has wrong type
3061  107	common/cmd_bootm.c	Kernel subimage type OK
3062 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
3063  108	common/cmd_bootm.c	Got kernel subimage data/size
3064 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
3065 -109	common/cmd_bootm.c	Can't get kernel subimage type
3066 -110	common/cmd_bootm.c	Can't get kernel subimage comp
3067 -111	common/cmd_bootm.c	Can't get kernel subimage os
3068 -112	common/cmd_bootm.c	Can't get kernel subimage load address
3069 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
3070
3071  120	common/image.c		Start initial ramdisk verification
3072 -120	common/image.c		Ramdisk FIT image has incorrect format
3073  121	common/image.c		Ramdisk FIT image has correct format
3074  122	common/image.c		No ramdisk subimage unit name, using configuration
3075 -122	common/image.c		Can't get configuration for ramdisk subimage
3076  123	common/image.c		Ramdisk unit name specified
3077 -124	common/image.c		Can't get ramdisk subimage node offset
3078  125	common/image.c		Got ramdisk subimage node offset
3079 -125	common/image.c		Ramdisk subimage hash verification failed
3080  126	common/image.c		Ramdisk subimage hash verification OK
3081 -126	common/image.c		Ramdisk subimage for unsupported architecture
3082  127	common/image.c		Architecture check OK
3083 -127	common/image.c		Can't get ramdisk subimage data/size
3084  128	common/image.c		Got ramdisk subimage data/size
3085  129	common/image.c		Can't get ramdisk load address
3086 -129	common/image.c		Got ramdisk load address
3087
3088 -130	common/cmd_doc.c	Incorrect FIT image format
3089  131	common/cmd_doc.c	FIT image format OK
3090
3091 -140	common/cmd_ide.c	Incorrect FIT image format
3092  141	common/cmd_ide.c	FIT image format OK
3093
3094 -150	common/cmd_nand.c	Incorrect FIT image format
3095  151	common/cmd_nand.c	FIT image format OK
3096
3097- legacy image format:
3098		CONFIG_IMAGE_FORMAT_LEGACY
3099		enables the legacy image format support in U-Boot.
3100
3101		Default:
3102		enabled if CONFIG_FIT_SIGNATURE is not defined.
3103
3104		CONFIG_DISABLE_IMAGE_LEGACY
3105		disable the legacy image format
3106
3107		This define is introduced, as the legacy image format is
3108		enabled per default for backward compatibility.
3109
3110- FIT image support:
3111		CONFIG_FIT_DISABLE_SHA256
3112		Supporting SHA256 hashes has quite an impact on binary size.
3113		For constrained systems sha256 hash support can be disabled
3114		with this option.
3115
3116		TODO(sjg@chromium.org): Adjust this option to be positive,
3117		and move it to Kconfig
3118
3119- Standalone program support:
3120		CONFIG_STANDALONE_LOAD_ADDR
3121
3122		This option defines a board specific value for the
3123		address where standalone program gets loaded, thus
3124		overwriting the architecture dependent default
3125		settings.
3126
3127- Frame Buffer Address:
3128		CONFIG_FB_ADDR
3129
3130		Define CONFIG_FB_ADDR if you want to use specific
3131		address for frame buffer.  This is typically the case
3132		when using a graphics controller has separate video
3133		memory.  U-Boot will then place the frame buffer at
3134		the given address instead of dynamically reserving it
3135		in system RAM by calling lcd_setmem(), which grabs
3136		the memory for the frame buffer depending on the
3137		configured panel size.
3138
3139		Please see board_init_f function.
3140
3141- Automatic software updates via TFTP server
3142		CONFIG_UPDATE_TFTP
3143		CONFIG_UPDATE_TFTP_CNT_MAX
3144		CONFIG_UPDATE_TFTP_MSEC_MAX
3145
3146		These options enable and control the auto-update feature;
3147		for a more detailed description refer to doc/README.update.
3148
3149- MTD Support (mtdparts command, UBI support)
3150		CONFIG_MTD_DEVICE
3151
3152		Adds the MTD device infrastructure from the Linux kernel.
3153		Needed for mtdparts command support.
3154
3155		CONFIG_MTD_PARTITIONS
3156
3157		Adds the MTD partitioning infrastructure from the Linux
3158		kernel. Needed for UBI support.
3159
3160- UBI support
3161		CONFIG_CMD_UBI
3162
3163		Adds commands for interacting with MTD partitions formatted
3164		with the UBI flash translation layer
3165
3166		Requires also defining CONFIG_RBTREE
3167
3168		CONFIG_UBI_SILENCE_MSG
3169
3170		Make the verbose messages from UBI stop printing.  This leaves
3171		warnings and errors enabled.
3172
3173
3174		CONFIG_MTD_UBI_WL_THRESHOLD
3175		This parameter defines the maximum difference between the highest
3176		erase counter value and the lowest erase counter value of eraseblocks
3177		of UBI devices. When this threshold is exceeded, UBI starts performing
3178		wear leveling by means of moving data from eraseblock with low erase
3179		counter to eraseblocks with high erase counter.
3180
3181		The default value should be OK for SLC NAND flashes, NOR flashes and
3182		other flashes which have eraseblock life-cycle 100000 or more.
3183		However, in case of MLC NAND flashes which typically have eraseblock
3184		life-cycle less than 10000, the threshold should be lessened (e.g.,
3185		to 128 or 256, although it does not have to be power of 2).
3186
3187		default: 4096
3188
3189		CONFIG_MTD_UBI_BEB_LIMIT
3190		This option specifies the maximum bad physical eraseblocks UBI
3191		expects on the MTD device (per 1024 eraseblocks). If the
3192		underlying flash does not admit of bad eraseblocks (e.g. NOR
3193		flash), this value is ignored.
3194
3195		NAND datasheets often specify the minimum and maximum NVM
3196		(Number of Valid Blocks) for the flashes' endurance lifetime.
3197		The maximum expected bad eraseblocks per 1024 eraseblocks
3198		then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
3199		which gives 20 for most NANDs (MaxNVB is basically the total
3200		count of eraseblocks on the chip).
3201
3202		To put it differently, if this value is 20, UBI will try to
3203		reserve about 1.9% of physical eraseblocks for bad blocks
3204		handling. And that will be 1.9% of eraseblocks on the entire
3205		NAND chip, not just the MTD partition UBI attaches. This means
3206		that if you have, say, a NAND flash chip admits maximum 40 bad
3207		eraseblocks, and it is split on two MTD partitions of the same
3208		size, UBI will reserve 40 eraseblocks when attaching a
3209		partition.
3210
3211		default: 20
3212
3213		CONFIG_MTD_UBI_FASTMAP
3214		Fastmap is a mechanism which allows attaching an UBI device
3215		in nearly constant time. Instead of scanning the whole MTD device it
3216		only has to locate a checkpoint (called fastmap) on the device.
3217		The on-flash fastmap contains all information needed to attach
3218		the device. Using fastmap makes only sense on large devices where
3219		attaching by scanning takes long. UBI will not automatically install
3220		a fastmap on old images, but you can set the UBI parameter
3221		CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
3222		that fastmap-enabled images are still usable with UBI implementations
3223		without	fastmap support. On typical flash devices the whole fastmap
3224		fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
3225
3226		CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
3227		Set this parameter to enable fastmap automatically on images
3228		without a fastmap.
3229		default: 0
3230
3231		CONFIG_MTD_UBI_FM_DEBUG
3232		Enable UBI fastmap debug
3233		default: 0
3234
3235- UBIFS support
3236		CONFIG_CMD_UBIFS
3237
3238		Adds commands for interacting with UBI volumes formatted as
3239		UBIFS.  UBIFS is read-only in u-boot.
3240
3241		Requires UBI support as well as CONFIG_LZO
3242
3243		CONFIG_UBIFS_SILENCE_MSG
3244
3245		Make the verbose messages from UBIFS stop printing.  This leaves
3246		warnings and errors enabled.
3247
3248- SPL framework
3249		CONFIG_SPL
3250		Enable building of SPL globally.
3251
3252		CONFIG_SPL_LDSCRIPT
3253		LDSCRIPT for linking the SPL binary.
3254
3255		CONFIG_SPL_MAX_FOOTPRINT
3256		Maximum size in memory allocated to the SPL, BSS included.
3257		When defined, the linker checks that the actual memory
3258		used by SPL from _start to __bss_end does not exceed it.
3259		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3260		must not be both defined at the same time.
3261
3262		CONFIG_SPL_MAX_SIZE
3263		Maximum size of the SPL image (text, data, rodata, and
3264		linker lists sections), BSS excluded.
3265		When defined, the linker checks that the actual size does
3266		not exceed it.
3267
3268		CONFIG_SPL_TEXT_BASE
3269		TEXT_BASE for linking the SPL binary.
3270
3271		CONFIG_SPL_RELOC_TEXT_BASE
3272		Address to relocate to.  If unspecified, this is equal to
3273		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3274
3275		CONFIG_SPL_BSS_START_ADDR
3276		Link address for the BSS within the SPL binary.
3277
3278		CONFIG_SPL_BSS_MAX_SIZE
3279		Maximum size in memory allocated to the SPL BSS.
3280		When defined, the linker checks that the actual memory used
3281		by SPL from __bss_start to __bss_end does not exceed it.
3282		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3283		must not be both defined at the same time.
3284
3285		CONFIG_SPL_STACK
3286		Adress of the start of the stack SPL will use
3287
3288		CONFIG_SPL_PANIC_ON_RAW_IMAGE
3289		When defined, SPL will panic() if the image it has
3290		loaded does not have a signature.
3291		Defining this is useful when code which loads images
3292		in SPL cannot guarantee that absolutely all read errors
3293		will be caught.
3294		An example is the LPC32XX MLC NAND driver, which will
3295		consider that a completely unreadable NAND block is bad,
3296		and thus should be skipped silently.
3297
3298		CONFIG_SPL_ABORT_ON_RAW_IMAGE
3299		When defined, SPL will proceed to another boot method
3300		if the image it has loaded does not have a signature.
3301
3302		CONFIG_SPL_RELOC_STACK
3303		Adress of the start of the stack SPL will use after
3304		relocation.  If unspecified, this is equal to
3305		CONFIG_SPL_STACK.
3306
3307		CONFIG_SYS_SPL_MALLOC_START
3308		Starting address of the malloc pool used in SPL.
3309		When this option is set the full malloc is used in SPL and
3310		it is set up by spl_init() and before that, the simple malloc()
3311		can be used if CONFIG_SYS_MALLOC_F is defined.
3312
3313		CONFIG_SYS_SPL_MALLOC_SIZE
3314		The size of the malloc pool used in SPL.
3315
3316		CONFIG_SPL_FRAMEWORK
3317		Enable the SPL framework under common/.  This framework
3318		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3319		NAND loading of the Linux Kernel.
3320
3321		CONFIG_SPL_OS_BOOT
3322		Enable booting directly to an OS from SPL.
3323		See also: doc/README.falcon
3324
3325		CONFIG_SPL_DISPLAY_PRINT
3326		For ARM, enable an optional function to print more information
3327		about the running system.
3328
3329		CONFIG_SPL_INIT_MINIMAL
3330		Arch init code should be built for a very small image
3331
3332		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
3333		Partition on the MMC to load U-Boot from when the MMC is being
3334		used in raw mode
3335
3336		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3337		Sector to load kernel uImage from when MMC is being
3338		used in raw mode (for Falcon mode)
3339
3340		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3341		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3342		Sector and number of sectors to load kernel argument
3343		parameters from when MMC is being used in raw mode
3344		(for falcon mode)
3345
3346		CONFIG_SYS_MMCSD_FS_BOOT_PARTITION
3347		Partition on the MMC to load U-Boot from when the MMC is being
3348		used in fs mode
3349
3350		CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
3351		Filename to read to load U-Boot when reading from filesystem
3352
3353		CONFIG_SPL_FS_LOAD_KERNEL_NAME
3354		Filename to read to load kernel uImage when reading
3355		from filesystem (for Falcon mode)
3356
3357		CONFIG_SPL_FS_LOAD_ARGS_NAME
3358		Filename to read to load kernel argument parameters
3359		when reading from filesystem (for Falcon mode)
3360
3361		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3362		Set this for NAND SPL on PPC mpc83xx targets, so that
3363		start.S waits for the rest of the SPL to load before
3364		continuing (the hardware starts execution after just
3365		loading the first page rather than the full 4K).
3366
3367		CONFIG_SPL_SKIP_RELOCATE
3368		Avoid SPL relocation
3369
3370		CONFIG_SPL_NAND_BASE
3371		Include nand_base.c in the SPL.  Requires
3372		CONFIG_SPL_NAND_DRIVERS.
3373
3374		CONFIG_SPL_NAND_DRIVERS
3375		SPL uses normal NAND drivers, not minimal drivers.
3376
3377		CONFIG_SPL_NAND_ECC
3378		Include standard software ECC in the SPL
3379
3380		CONFIG_SPL_NAND_SIMPLE
3381		Support for NAND boot using simple NAND drivers that
3382		expose the cmd_ctrl() interface.
3383
3384		CONFIG_SPL_UBI
3385		Support for a lightweight UBI (fastmap) scanner and
3386		loader
3387
3388		CONFIG_SPL_NAND_RAW_ONLY
3389		Support to boot only raw u-boot.bin images. Use this only
3390		if you need to save space.
3391
3392		CONFIG_SPL_COMMON_INIT_DDR
3393		Set for common ddr init with serial presence detect in
3394		SPL binary.
3395
3396		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3397		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3398		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3399		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3400		CONFIG_SYS_NAND_ECCBYTES
3401		Defines the size and behavior of the NAND that SPL uses
3402		to read U-Boot
3403
3404		CONFIG_SPL_NAND_BOOT
3405		Add support NAND boot
3406
3407		CONFIG_SYS_NAND_U_BOOT_OFFS
3408		Location in NAND to read U-Boot from
3409
3410		CONFIG_SYS_NAND_U_BOOT_DST
3411		Location in memory to load U-Boot to
3412
3413		CONFIG_SYS_NAND_U_BOOT_SIZE
3414		Size of image to load
3415
3416		CONFIG_SYS_NAND_U_BOOT_START
3417		Entry point in loaded image to jump to
3418
3419		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3420		Define this if you need to first read the OOB and then the
3421		data. This is used, for example, on davinci platforms.
3422
3423		CONFIG_SPL_OMAP3_ID_NAND
3424		Support for an OMAP3-specific set of functions to return the
3425		ID and MFR of the first attached NAND chip, if present.
3426
3427		CONFIG_SPL_RAM_DEVICE
3428		Support for running image already present in ram, in SPL binary
3429
3430		CONFIG_SPL_PAD_TO
3431		Image offset to which the SPL should be padded before appending
3432		the SPL payload. By default, this is defined as
3433		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3434		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3435		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3436
3437		CONFIG_SPL_TARGET
3438		Final target image containing SPL and payload.  Some SPLs
3439		use an arch-specific makefile fragment instead, for
3440		example if more than one image needs to be produced.
3441
3442		CONFIG_FIT_SPL_PRINT
3443		Printing information about a FIT image adds quite a bit of
3444		code to SPL. So this is normally disabled in SPL. Use this
3445		option to re-enable it. This will affect the output of the
3446		bootm command when booting a FIT image.
3447
3448- TPL framework
3449		CONFIG_TPL
3450		Enable building of TPL globally.
3451
3452		CONFIG_TPL_PAD_TO
3453		Image offset to which the TPL should be padded before appending
3454		the TPL payload. By default, this is defined as
3455		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3456		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3457		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3458
3459- Interrupt support (PPC):
3460
3461		There are common interrupt_init() and timer_interrupt()
3462		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3463		for CPU specific initialization. interrupt_init_cpu()
3464		should set decrementer_count to appropriate value. If
3465		CPU resets decrementer automatically after interrupt
3466		(ppc4xx) it should set decrementer_count to zero.
3467		timer_interrupt() calls timer_interrupt_cpu() for CPU
3468		specific handling. If board has watchdog / status_led
3469		/ other_activity_monitor it works automatically from
3470		general timer_interrupt().
3471
3472
3473Board initialization settings:
3474------------------------------
3475
3476During Initialization u-boot calls a number of board specific functions
3477to allow the preparation of board specific prerequisites, e.g. pin setup
3478before drivers are initialized. To enable these callbacks the
3479following configuration macros have to be defined. Currently this is
3480architecture specific, so please check arch/your_architecture/lib/board.c
3481typically in board_init_f() and board_init_r().
3482
3483- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3484- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3485- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3486- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3487
3488Configuration Settings:
3489-----------------------
3490
3491- CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
3492		Optionally it can be defined to support 64-bit memory commands.
3493
3494- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3495		undefine this when you're short of memory.
3496
3497- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3498		width of the commands listed in the 'help' command output.
3499
3500- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3501		prompt for user input.
3502
3503- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3504
3505- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3506
3507- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3508
3509- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3510		the application (usually a Linux kernel) when it is
3511		booted
3512
3513- CONFIG_SYS_BAUDRATE_TABLE:
3514		List of legal baudrate settings for this board.
3515
3516- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3517		Begin and End addresses of the area used by the
3518		simple memory test.
3519
3520- CONFIG_SYS_ALT_MEMTEST:
3521		Enable an alternate, more extensive memory test.
3522
3523- CONFIG_SYS_MEMTEST_SCRATCH:
3524		Scratch address used by the alternate memory test
3525		You only need to set this if address zero isn't writeable
3526
3527- CONFIG_SYS_MEM_RESERVE_SECURE
3528		Only implemented for ARMv8 for now.
3529		If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
3530		is substracted from total RAM and won't be reported to OS.
3531		This memory can be used as secure memory. A variable
3532		gd->arch.secure_ram is used to track the location. In systems
3533		the RAM base is not zero, or RAM is divided into banks,
3534		this variable needs to be recalcuated to get the address.
3535
3536- CONFIG_SYS_MEM_TOP_HIDE:
3537		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3538		this specified memory area will get subtracted from the top
3539		(end) of RAM and won't get "touched" at all by U-Boot. By
3540		fixing up gd->ram_size the Linux kernel should gets passed
3541		the now "corrected" memory size and won't touch it either.
3542		This should work for arch/ppc and arch/powerpc. Only Linux
3543		board ports in arch/powerpc with bootwrapper support that
3544		recalculate the memory size from the SDRAM controller setup
3545		will have to get fixed in Linux additionally.
3546
3547		This option can be used as a workaround for the 440EPx/GRx
3548		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3549		be touched.
3550
3551		WARNING: Please make sure that this value is a multiple of
3552		the Linux page size (normally 4k). If this is not the case,
3553		then the end address of the Linux memory will be located at a
3554		non page size aligned address and this could cause major
3555		problems.
3556
3557- CONFIG_SYS_LOADS_BAUD_CHANGE:
3558		Enable temporary baudrate change while serial download
3559
3560- CONFIG_SYS_SDRAM_BASE:
3561		Physical start address of SDRAM. _Must_ be 0 here.
3562
3563- CONFIG_SYS_FLASH_BASE:
3564		Physical start address of Flash memory.
3565
3566- CONFIG_SYS_MONITOR_BASE:
3567		Physical start address of boot monitor code (set by
3568		make config files to be same as the text base address
3569		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3570		CONFIG_SYS_FLASH_BASE when booting from flash.
3571
3572- CONFIG_SYS_MONITOR_LEN:
3573		Size of memory reserved for monitor code, used to
3574		determine _at_compile_time_ (!) if the environment is
3575		embedded within the U-Boot image, or in a separate
3576		flash sector.
3577
3578- CONFIG_SYS_MALLOC_LEN:
3579		Size of DRAM reserved for malloc() use.
3580
3581- CONFIG_SYS_MALLOC_F_LEN
3582		Size of the malloc() pool for use before relocation. If
3583		this is defined, then a very simple malloc() implementation
3584		will become available before relocation. The address is just
3585		below the global data, and the stack is moved down to make
3586		space.
3587
3588		This feature allocates regions with increasing addresses
3589		within the region. calloc() is supported, but realloc()
3590		is not available. free() is supported but does nothing.
3591		The memory will be freed (or in fact just forgotten) when
3592		U-Boot relocates itself.
3593
3594- CONFIG_SYS_MALLOC_SIMPLE
3595		Provides a simple and small malloc() and calloc() for those
3596		boards which do not use the full malloc in SPL (which is
3597		enabled with CONFIG_SYS_SPL_MALLOC_START).
3598
3599- CONFIG_SYS_NONCACHED_MEMORY:
3600		Size of non-cached memory area. This area of memory will be
3601		typically located right below the malloc() area and mapped
3602		uncached in the MMU. This is useful for drivers that would
3603		otherwise require a lot of explicit cache maintenance. For
3604		some drivers it's also impossible to properly maintain the
3605		cache. For example if the regions that need to be flushed
3606		are not a multiple of the cache-line size, *and* padding
3607		cannot be allocated between the regions to align them (i.e.
3608		if the HW requires a contiguous array of regions, and the
3609		size of each region is not cache-aligned), then a flush of
3610		one region may result in overwriting data that hardware has
3611		written to another region in the same cache-line. This can
3612		happen for example in network drivers where descriptors for
3613		buffers are typically smaller than the CPU cache-line (e.g.
3614		16 bytes vs. 32 or 64 bytes).
3615
3616		Non-cached memory is only supported on 32-bit ARM at present.
3617
3618- CONFIG_SYS_BOOTM_LEN:
3619		Normally compressed uImages are limited to an
3620		uncompressed size of 8 MBytes. If this is not enough,
3621		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3622		to adjust this setting to your needs.
3623
3624- CONFIG_SYS_BOOTMAPSZ:
3625		Maximum size of memory mapped by the startup code of
3626		the Linux kernel; all data that must be processed by
3627		the Linux kernel (bd_info, boot arguments, FDT blob if
3628		used) must be put below this limit, unless "bootm_low"
3629		environment variable is defined and non-zero. In such case
3630		all data for the Linux kernel must be between "bootm_low"
3631		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3632		variable "bootm_mapsize" will override the value of
3633		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3634		then the value in "bootm_size" will be used instead.
3635
3636- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3637		Enable initrd_high functionality.  If defined then the
3638		initrd_high feature is enabled and the bootm ramdisk subcommand
3639		is enabled.
3640
3641- CONFIG_SYS_BOOT_GET_CMDLINE:
3642		Enables allocating and saving kernel cmdline in space between
3643		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3644
3645- CONFIG_SYS_BOOT_GET_KBD:
3646		Enables allocating and saving a kernel copy of the bd_info in
3647		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3648
3649- CONFIG_SYS_MAX_FLASH_BANKS:
3650		Max number of Flash memory banks
3651
3652- CONFIG_SYS_MAX_FLASH_SECT:
3653		Max number of sectors on a Flash chip
3654
3655- CONFIG_SYS_FLASH_ERASE_TOUT:
3656		Timeout for Flash erase operations (in ms)
3657
3658- CONFIG_SYS_FLASH_WRITE_TOUT:
3659		Timeout for Flash write operations (in ms)
3660
3661- CONFIG_SYS_FLASH_LOCK_TOUT
3662		Timeout for Flash set sector lock bit operation (in ms)
3663
3664- CONFIG_SYS_FLASH_UNLOCK_TOUT
3665		Timeout for Flash clear lock bits operation (in ms)
3666
3667- CONFIG_SYS_FLASH_PROTECTION
3668		If defined, hardware flash sectors protection is used
3669		instead of U-Boot software protection.
3670
3671- CONFIG_SYS_DIRECT_FLASH_TFTP:
3672
3673		Enable TFTP transfers directly to flash memory;
3674		without this option such a download has to be
3675		performed in two steps: (1) download to RAM, and (2)
3676		copy from RAM to flash.
3677
3678		The two-step approach is usually more reliable, since
3679		you can check if the download worked before you erase
3680		the flash, but in some situations (when system RAM is
3681		too limited to allow for a temporary copy of the
3682		downloaded image) this option may be very useful.
3683
3684- CONFIG_SYS_FLASH_CFI:
3685		Define if the flash driver uses extra elements in the
3686		common flash structure for storing flash geometry.
3687
3688- CONFIG_FLASH_CFI_DRIVER
3689		This option also enables the building of the cfi_flash driver
3690		in the drivers directory
3691
3692- CONFIG_FLASH_CFI_MTD
3693		This option enables the building of the cfi_mtd driver
3694		in the drivers directory. The driver exports CFI flash
3695		to the MTD layer.
3696
3697- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3698		Use buffered writes to flash.
3699
3700- CONFIG_FLASH_SPANSION_S29WS_N
3701		s29ws-n MirrorBit flash has non-standard addresses for buffered
3702		write commands.
3703
3704- CONFIG_SYS_FLASH_QUIET_TEST
3705		If this option is defined, the common CFI flash doesn't
3706		print it's warning upon not recognized FLASH banks. This
3707		is useful, if some of the configured banks are only
3708		optionally available.
3709
3710- CONFIG_FLASH_SHOW_PROGRESS
3711		If defined (must be an integer), print out countdown
3712		digits and dots.  Recommended value: 45 (9..1) for 80
3713		column displays, 15 (3..1) for 40 column displays.
3714
3715- CONFIG_FLASH_VERIFY
3716		If defined, the content of the flash (destination) is compared
3717		against the source after the write operation. An error message
3718		will be printed when the contents are not identical.
3719		Please note that this option is useless in nearly all cases,
3720		since such flash programming errors usually are detected earlier
3721		while unprotecting/erasing/programming. Please only enable
3722		this option if you really know what you are doing.
3723
3724- CONFIG_SYS_RX_ETH_BUFFER:
3725		Defines the number of Ethernet receive buffers. On some
3726		Ethernet controllers it is recommended to set this value
3727		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3728		buffers can be full shortly after enabling the interface
3729		on high Ethernet traffic.
3730		Defaults to 4 if not defined.
3731
3732- CONFIG_ENV_MAX_ENTRIES
3733
3734	Maximum number of entries in the hash table that is used
3735	internally to store the environment settings. The default
3736	setting is supposed to be generous and should work in most
3737	cases. This setting can be used to tune behaviour; see
3738	lib/hashtable.c for details.
3739
3740- CONFIG_ENV_FLAGS_LIST_DEFAULT
3741- CONFIG_ENV_FLAGS_LIST_STATIC
3742	Enable validation of the values given to environment variables when
3743	calling env set.  Variables can be restricted to only decimal,
3744	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3745	the variables can also be restricted to IP address or MAC address.
3746
3747	The format of the list is:
3748		type_attribute = [s|d|x|b|i|m]
3749		access_attribute = [a|r|o|c]
3750		attributes = type_attribute[access_attribute]
3751		entry = variable_name[:attributes]
3752		list = entry[,list]
3753
3754	The type attributes are:
3755		s - String (default)
3756		d - Decimal
3757		x - Hexadecimal
3758		b - Boolean ([1yYtT|0nNfF])
3759		i - IP address
3760		m - MAC address
3761
3762	The access attributes are:
3763		a - Any (default)
3764		r - Read-only
3765		o - Write-once
3766		c - Change-default
3767
3768	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3769		Define this to a list (string) to define the ".flags"
3770		environment variable in the default or embedded environment.
3771
3772	- CONFIG_ENV_FLAGS_LIST_STATIC
3773		Define this to a list (string) to define validation that
3774		should be done if an entry is not found in the ".flags"
3775		environment variable.  To override a setting in the static
3776		list, simply add an entry for the same variable name to the
3777		".flags" variable.
3778
3779	If CONFIG_REGEX is defined, the variable_name above is evaluated as a
3780	regular expression. This allows multiple variables to define the same
3781	flags without explicitly listing them for each variable.
3782
3783- CONFIG_ENV_ACCESS_IGNORE_FORCE
3784	If defined, don't allow the -f switch to env set override variable
3785	access flags.
3786
3787- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
3788	This is set by OMAP boards for the max time that reset should
3789	be asserted. See doc/README.omap-reset-time for details on how
3790	the value can be calculated on a given board.
3791
3792- CONFIG_USE_STDINT
3793	If stdint.h is available with your toolchain you can define this
3794	option to enable it. You can provide option 'USE_STDINT=1' when
3795	building U-Boot to enable this.
3796
3797The following definitions that deal with the placement and management
3798of environment data (variable area); in general, we support the
3799following configurations:
3800
3801- CONFIG_BUILD_ENVCRC:
3802
3803	Builds up envcrc with the target environment so that external utils
3804	may easily extract it and embed it in final U-Boot images.
3805
3806- CONFIG_ENV_IS_IN_FLASH:
3807
3808	Define this if the environment is in flash memory.
3809
3810	a) The environment occupies one whole flash sector, which is
3811	   "embedded" in the text segment with the U-Boot code. This
3812	   happens usually with "bottom boot sector" or "top boot
3813	   sector" type flash chips, which have several smaller
3814	   sectors at the start or the end. For instance, such a
3815	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3816	   such a case you would place the environment in one of the
3817	   4 kB sectors - with U-Boot code before and after it. With
3818	   "top boot sector" type flash chips, you would put the
3819	   environment in one of the last sectors, leaving a gap
3820	   between U-Boot and the environment.
3821
3822	- CONFIG_ENV_OFFSET:
3823
3824	   Offset of environment data (variable area) to the
3825	   beginning of flash memory; for instance, with bottom boot
3826	   type flash chips the second sector can be used: the offset
3827	   for this sector is given here.
3828
3829	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3830
3831	- CONFIG_ENV_ADDR:
3832
3833	   This is just another way to specify the start address of
3834	   the flash sector containing the environment (instead of
3835	   CONFIG_ENV_OFFSET).
3836
3837	- CONFIG_ENV_SECT_SIZE:
3838
3839	   Size of the sector containing the environment.
3840
3841
3842	b) Sometimes flash chips have few, equal sized, BIG sectors.
3843	   In such a case you don't want to spend a whole sector for
3844	   the environment.
3845
3846	- CONFIG_ENV_SIZE:
3847
3848	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3849	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3850	   of this flash sector for the environment. This saves
3851	   memory for the RAM copy of the environment.
3852
3853	   It may also save flash memory if you decide to use this
3854	   when your environment is "embedded" within U-Boot code,
3855	   since then the remainder of the flash sector could be used
3856	   for U-Boot code. It should be pointed out that this is
3857	   STRONGLY DISCOURAGED from a robustness point of view:
3858	   updating the environment in flash makes it always
3859	   necessary to erase the WHOLE sector. If something goes
3860	   wrong before the contents has been restored from a copy in
3861	   RAM, your target system will be dead.
3862
3863	- CONFIG_ENV_ADDR_REDUND
3864	  CONFIG_ENV_SIZE_REDUND
3865
3866	   These settings describe a second storage area used to hold
3867	   a redundant copy of the environment data, so that there is
3868	   a valid backup copy in case there is a power failure during
3869	   a "saveenv" operation.
3870
3871BE CAREFUL! Any changes to the flash layout, and some changes to the
3872source code will make it necessary to adapt <board>/u-boot.lds*
3873accordingly!
3874
3875
3876- CONFIG_ENV_IS_IN_NVRAM:
3877
3878	Define this if you have some non-volatile memory device
3879	(NVRAM, battery buffered SRAM) which you want to use for the
3880	environment.
3881
3882	- CONFIG_ENV_ADDR:
3883	- CONFIG_ENV_SIZE:
3884
3885	  These two #defines are used to determine the memory area you
3886	  want to use for environment. It is assumed that this memory
3887	  can just be read and written to, without any special
3888	  provision.
3889
3890BE CAREFUL! The first access to the environment happens quite early
3891in U-Boot initialization (when we try to get the setting of for the
3892console baudrate). You *MUST* have mapped your NVRAM area then, or
3893U-Boot will hang.
3894
3895Please note that even with NVRAM we still use a copy of the
3896environment in RAM: we could work on NVRAM directly, but we want to
3897keep settings there always unmodified except somebody uses "saveenv"
3898to save the current settings.
3899
3900
3901- CONFIG_ENV_IS_IN_EEPROM:
3902
3903	Use this if you have an EEPROM or similar serial access
3904	device and a driver for it.
3905
3906	- CONFIG_ENV_OFFSET:
3907	- CONFIG_ENV_SIZE:
3908
3909	  These two #defines specify the offset and size of the
3910	  environment area within the total memory of your EEPROM.
3911
3912	- CONFIG_SYS_I2C_EEPROM_ADDR:
3913	  If defined, specified the chip address of the EEPROM device.
3914	  The default address is zero.
3915
3916	- CONFIG_SYS_I2C_EEPROM_BUS:
3917	  If defined, specified the i2c bus of the EEPROM device.
3918
3919	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3920	  If defined, the number of bits used to address bytes in a
3921	  single page in the EEPROM device.  A 64 byte page, for example
3922	  would require six bits.
3923
3924	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3925	  If defined, the number of milliseconds to delay between
3926	  page writes.	The default is zero milliseconds.
3927
3928	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3929	  The length in bytes of the EEPROM memory array address.  Note
3930	  that this is NOT the chip address length!
3931
3932	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3933	  EEPROM chips that implement "address overflow" are ones
3934	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3935	  address and the extra bits end up in the "chip address" bit
3936	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3937	  byte chips.
3938
3939	  Note that we consider the length of the address field to
3940	  still be one byte because the extra address bits are hidden
3941	  in the chip address.
3942
3943	- CONFIG_SYS_EEPROM_SIZE:
3944	  The size in bytes of the EEPROM device.
3945
3946	- CONFIG_ENV_EEPROM_IS_ON_I2C
3947	  define this, if you have I2C and SPI activated, and your
3948	  EEPROM, which holds the environment, is on the I2C bus.
3949
3950	- CONFIG_I2C_ENV_EEPROM_BUS
3951	  if you have an Environment on an EEPROM reached over
3952	  I2C muxes, you can define here, how to reach this
3953	  EEPROM. For example:
3954
3955	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
3956
3957	  EEPROM which holds the environment, is reached over
3958	  a pca9547 i2c mux with address 0x70, channel 3.
3959
3960- CONFIG_ENV_IS_IN_DATAFLASH:
3961
3962	Define this if you have a DataFlash memory device which you
3963	want to use for the environment.
3964
3965	- CONFIG_ENV_OFFSET:
3966	- CONFIG_ENV_ADDR:
3967	- CONFIG_ENV_SIZE:
3968
3969	  These three #defines specify the offset and size of the
3970	  environment area within the total memory of your DataFlash placed
3971	  at the specified address.
3972
3973- CONFIG_ENV_IS_IN_SPI_FLASH:
3974
3975	Define this if you have a SPI Flash memory device which you
3976	want to use for the environment.
3977
3978	- CONFIG_ENV_OFFSET:
3979	- CONFIG_ENV_SIZE:
3980
3981	  These two #defines specify the offset and size of the
3982	  environment area within the SPI Flash. CONFIG_ENV_OFFSET must be
3983	  aligned to an erase sector boundary.
3984
3985	- CONFIG_ENV_SECT_SIZE:
3986
3987	  Define the SPI flash's sector size.
3988
3989	- CONFIG_ENV_OFFSET_REDUND (optional):
3990
3991	  This setting describes a second storage area of CONFIG_ENV_SIZE
3992	  size used to hold a redundant copy of the environment data, so
3993	  that there is a valid backup copy in case there is a power failure
3994	  during a "saveenv" operation. CONFIG_ENV_OFFSET_REDUND must be
3995	  aligned to an erase sector boundary.
3996
3997	- CONFIG_ENV_SPI_BUS (optional):
3998	- CONFIG_ENV_SPI_CS (optional):
3999
4000	  Define the SPI bus and chip select. If not defined they will be 0.
4001
4002	- CONFIG_ENV_SPI_MAX_HZ (optional):
4003
4004	  Define the SPI max work clock. If not defined then use 1MHz.
4005
4006	- CONFIG_ENV_SPI_MODE (optional):
4007
4008	  Define the SPI work mode. If not defined then use SPI_MODE_3.
4009
4010- CONFIG_ENV_IS_IN_REMOTE:
4011
4012	Define this if you have a remote memory space which you
4013	want to use for the local device's environment.
4014
4015	- CONFIG_ENV_ADDR:
4016	- CONFIG_ENV_SIZE:
4017
4018	  These two #defines specify the address and size of the
4019	  environment area within the remote memory space. The
4020	  local device can get the environment from remote memory
4021	  space by SRIO or PCIE links.
4022
4023BE CAREFUL! For some special cases, the local device can not use
4024"saveenv" command. For example, the local device will get the
4025environment stored in a remote NOR flash by SRIO or PCIE link,
4026but it can not erase, write this NOR flash by SRIO or PCIE interface.
4027
4028- CONFIG_ENV_IS_IN_NAND:
4029
4030	Define this if you have a NAND device which you want to use
4031	for the environment.
4032
4033	- CONFIG_ENV_OFFSET:
4034	- CONFIG_ENV_SIZE:
4035
4036	  These two #defines specify the offset and size of the environment
4037	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
4038	  aligned to an erase block boundary.
4039
4040	- CONFIG_ENV_OFFSET_REDUND (optional):
4041
4042	  This setting describes a second storage area of CONFIG_ENV_SIZE
4043	  size used to hold a redundant copy of the environment data, so
4044	  that there is a valid backup copy in case there is a power failure
4045	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_REDUND must be
4046	  aligned to an erase block boundary.
4047
4048	- CONFIG_ENV_RANGE (optional):
4049
4050	  Specifies the length of the region in which the environment
4051	  can be written.  This should be a multiple of the NAND device's
4052	  block size.  Specifying a range with more erase blocks than
4053	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
4054	  the range to be avoided.
4055
4056	- CONFIG_ENV_OFFSET_OOB (optional):
4057
4058	  Enables support for dynamically retrieving the offset of the
4059	  environment from block zero's out-of-band data.  The
4060	  "nand env.oob" command can be used to record this offset.
4061	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
4062	  using CONFIG_ENV_OFFSET_OOB.
4063
4064- CONFIG_NAND_ENV_DST
4065
4066	Defines address in RAM to which the nand_spl code should copy the
4067	environment. If redundant environment is used, it will be copied to
4068	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
4069
4070- CONFIG_ENV_IS_IN_UBI:
4071
4072	Define this if you have an UBI volume that you want to use for the
4073	environment.  This has the benefit of wear-leveling the environment
4074	accesses, which is important on NAND.
4075
4076	- CONFIG_ENV_UBI_PART:
4077
4078	  Define this to a string that is the mtd partition containing the UBI.
4079
4080	- CONFIG_ENV_UBI_VOLUME:
4081
4082	  Define this to the name of the volume that you want to store the
4083	  environment in.
4084
4085	- CONFIG_ENV_UBI_VOLUME_REDUND:
4086
4087	  Define this to the name of another volume to store a second copy of
4088	  the environment in.  This will enable redundant environments in UBI.
4089	  It is assumed that both volumes are in the same MTD partition.
4090
4091	- CONFIG_UBI_SILENCE_MSG
4092	- CONFIG_UBIFS_SILENCE_MSG
4093
4094	  You will probably want to define these to avoid a really noisy system
4095	  when storing the env in UBI.
4096
4097- CONFIG_ENV_IS_IN_FAT:
4098       Define this if you want to use the FAT file system for the environment.
4099
4100       - FAT_ENV_INTERFACE:
4101
4102         Define this to a string that is the name of the block device.
4103
4104       - FAT_ENV_DEVICE_AND_PART:
4105
4106         Define this to a string to specify the partition of the device. It can
4107         be as following:
4108
4109           "D:P", "D:0", "D", "D:" or "D:auto" (D, P are integers. And P >= 1)
4110               - "D:P": device D partition P. Error occurs if device D has no
4111                        partition table.
4112               - "D:0": device D.
4113               - "D" or "D:": device D partition 1 if device D has partition
4114                              table, or the whole device D if has no partition
4115                              table.
4116               - "D:auto": first partition in device D with bootable flag set.
4117                           If none, first valid partition in device D. If no
4118                           partition table then means device D.
4119
4120       - FAT_ENV_FILE:
4121
4122         It's a string of the FAT file name. This file use to store the
4123         environment.
4124
4125       - CONFIG_FAT_WRITE:
4126         This should be defined. Otherwise it cannot save the environment file.
4127
4128- CONFIG_ENV_IS_IN_MMC:
4129
4130	Define this if you have an MMC device which you want to use for the
4131	environment.
4132
4133	- CONFIG_SYS_MMC_ENV_DEV:
4134
4135	  Specifies which MMC device the environment is stored in.
4136
4137	- CONFIG_SYS_MMC_ENV_PART (optional):
4138
4139	  Specifies which MMC partition the environment is stored in. If not
4140	  set, defaults to partition 0, the user area. Common values might be
4141	  1 (first MMC boot partition), 2 (second MMC boot partition).
4142
4143	- CONFIG_ENV_OFFSET:
4144	- CONFIG_ENV_SIZE:
4145
4146	  These two #defines specify the offset and size of the environment
4147	  area within the specified MMC device.
4148
4149	  If offset is positive (the usual case), it is treated as relative to
4150	  the start of the MMC partition. If offset is negative, it is treated
4151	  as relative to the end of the MMC partition. This can be useful if
4152	  your board may be fitted with different MMC devices, which have
4153	  different sizes for the MMC partitions, and you always want the
4154	  environment placed at the very end of the partition, to leave the
4155	  maximum possible space before it, to store other data.
4156
4157	  These two values are in units of bytes, but must be aligned to an
4158	  MMC sector boundary.
4159
4160	- CONFIG_ENV_OFFSET_REDUND (optional):
4161
4162	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
4163	  hold a redundant copy of the environment data. This provides a
4164	  valid backup copy in case the other copy is corrupted, e.g. due
4165	  to a power failure during a "saveenv" operation.
4166
4167	  This value may also be positive or negative; this is handled in the
4168	  same way as CONFIG_ENV_OFFSET.
4169
4170	  This value is also in units of bytes, but must also be aligned to
4171	  an MMC sector boundary.
4172
4173	- CONFIG_ENV_SIZE_REDUND (optional):
4174
4175	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
4176	  set. If this value is set, it must be set to the same value as
4177	  CONFIG_ENV_SIZE.
4178
4179- CONFIG_SYS_SPI_INIT_OFFSET
4180
4181	Defines offset to the initial SPI buffer area in DPRAM. The
4182	area is used at an early stage (ROM part) if the environment
4183	is configured to reside in the SPI EEPROM: We need a 520 byte
4184	scratch DPRAM area. It is used between the two initialization
4185	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
4186	to be a good choice since it makes it far enough from the
4187	start of the data area as well as from the stack pointer.
4188
4189Please note that the environment is read-only until the monitor
4190has been relocated to RAM and a RAM copy of the environment has been
4191created; also, when using EEPROM you will have to use getenv_f()
4192until then to read environment variables.
4193
4194The environment is protected by a CRC32 checksum. Before the monitor
4195is relocated into RAM, as a result of a bad CRC you will be working
4196with the compiled-in default environment - *silently*!!! [This is
4197necessary, because the first environment variable we need is the
4198"baudrate" setting for the console - if we have a bad CRC, we don't
4199have any device yet where we could complain.]
4200
4201Note: once the monitor has been relocated, then it will complain if
4202the default environment is used; a new CRC is computed as soon as you
4203use the "saveenv" command to store a valid environment.
4204
4205- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
4206		Echo the inverted Ethernet link state to the fault LED.
4207
4208		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
4209		      also needs to be defined.
4210
4211- CONFIG_SYS_FAULT_MII_ADDR:
4212		MII address of the PHY to check for the Ethernet link state.
4213
4214- CONFIG_NS16550_MIN_FUNCTIONS:
4215		Define this if you desire to only have use of the NS16550_init
4216		and NS16550_putc functions for the serial driver located at
4217		drivers/serial/ns16550.c.  This option is useful for saving
4218		space for already greatly restricted images, including but not
4219		limited to NAND_SPL configurations.
4220
4221- CONFIG_DISPLAY_BOARDINFO
4222		Display information about the board that U-Boot is running on
4223		when U-Boot starts up. The board function checkboard() is called
4224		to do this.
4225
4226- CONFIG_DISPLAY_BOARDINFO_LATE
4227		Similar to the previous option, but display this information
4228		later, once stdio is running and output goes to the LCD, if
4229		present.
4230
4231- CONFIG_BOARD_SIZE_LIMIT:
4232		Maximum size of the U-Boot image. When defined, the
4233		build system checks that the actual size does not
4234		exceed it.
4235
4236Low Level (hardware related) configuration options:
4237---------------------------------------------------
4238
4239- CONFIG_SYS_CACHELINE_SIZE:
4240		Cache Line Size of the CPU.
4241
4242- CONFIG_SYS_DEFAULT_IMMR:
4243		Default address of the IMMR after system reset.
4244
4245		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4246		and RPXsuper) to be able to adjust the position of
4247		the IMMR register after a reset.
4248
4249- CONFIG_SYS_CCSRBAR_DEFAULT:
4250		Default (power-on reset) physical address of CCSR on Freescale
4251		PowerPC SOCs.
4252
4253- CONFIG_SYS_CCSRBAR:
4254		Virtual address of CCSR.  On a 32-bit build, this is typically
4255		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4256
4257		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4258		for cross-platform code that uses that macro instead.
4259
4260- CONFIG_SYS_CCSRBAR_PHYS:
4261		Physical address of CCSR.  CCSR can be relocated to a new
4262		physical address, if desired.  In this case, this macro should
4263		be set to that address.	 Otherwise, it should be set to the
4264		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
4265		is typically relocated on 36-bit builds.  It is recommended
4266		that this macro be defined via the _HIGH and _LOW macros:
4267
4268		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4269			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4270
4271- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4272		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
4273		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
4274		used in assembly code, so it must not contain typecasts or
4275		integer size suffixes (e.g. "ULL").
4276
4277- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4278		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
4279		used in assembly code, so it must not contain typecasts or
4280		integer size suffixes (e.g. "ULL").
4281
4282- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
4283		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4284		forced to a value that ensures that CCSR is not relocated.
4285
4286- Floppy Disk Support:
4287		CONFIG_SYS_FDC_DRIVE_NUMBER
4288
4289		the default drive number (default value 0)
4290
4291		CONFIG_SYS_ISA_IO_STRIDE
4292
4293		defines the spacing between FDC chipset registers
4294		(default value 1)
4295
4296		CONFIG_SYS_ISA_IO_OFFSET
4297
4298		defines the offset of register from address. It
4299		depends on which part of the data bus is connected to
4300		the FDC chipset. (default value 0)
4301
4302		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4303		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4304		default value.
4305
4306		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4307		fdc_hw_init() is called at the beginning of the FDC
4308		setup. fdc_hw_init() must be provided by the board
4309		source code. It is used to make hardware-dependent
4310		initializations.
4311
4312- CONFIG_IDE_AHB:
4313		Most IDE controllers were designed to be connected with PCI
4314		interface. Only few of them were designed for AHB interface.
4315		When software is doing ATA command and data transfer to
4316		IDE devices through IDE-AHB controller, some additional
4317		registers accessing to these kind of IDE-AHB controller
4318		is required.
4319
4320- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4321		DO NOT CHANGE unless you know exactly what you're
4322		doing! (11-4) [MPC8xx/82xx systems only]
4323
4324- CONFIG_SYS_INIT_RAM_ADDR:
4325
4326		Start address of memory area that can be used for
4327		initial data and stack; please note that this must be
4328		writable memory that is working WITHOUT special
4329		initialization, i. e. you CANNOT use normal RAM which
4330		will become available only after programming the
4331		memory controller and running certain initialization
4332		sequences.
4333
4334		U-Boot uses the following memory types:
4335		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4336		- MPC824X: data cache
4337		- PPC4xx:  data cache
4338
4339- CONFIG_SYS_GBL_DATA_OFFSET:
4340
4341		Offset of the initial data structure in the memory
4342		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4343		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4344		data is located at the end of the available space
4345		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4346		GENERATED_GBL_DATA_SIZE), and the initial stack is just
4347		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4348		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4349
4350	Note:
4351		On the MPC824X (or other systems that use the data
4352		cache for initial memory) the address chosen for
4353		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4354		point to an otherwise UNUSED address space between
4355		the top of RAM and the start of the PCI space.
4356
4357- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4358
4359- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4360
4361- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4362
4363- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4364
4365- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4366
4367- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4368
4369- CONFIG_SYS_OR_TIMING_SDRAM:
4370		SDRAM timing
4371
4372- CONFIG_SYS_MAMR_PTA:
4373		periodic timer for refresh
4374
4375- CONFIG_SYS_DER:	Debug Event Register (37-47)
4376
4377- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4378  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4379  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4380  CONFIG_SYS_BR1_PRELIM:
4381		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4382
4383- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4384  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4385  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4386		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4387
4388- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4389  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4390		Machine Mode Register and Memory Periodic Timer
4391		Prescaler definitions (SDRAM timing)
4392
4393- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4394		enable I2C microcode relocation patch (MPC8xx);
4395		define relocation offset in DPRAM [DSP2]
4396
4397- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4398		enable SMC microcode relocation patch (MPC8xx);
4399		define relocation offset in DPRAM [SMC1]
4400
4401- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4402		enable SPI microcode relocation patch (MPC8xx);
4403		define relocation offset in DPRAM [SCC4]
4404
4405- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4406		Offset of the bootmode word in DPRAM used by post
4407		(Power On Self Tests). This definition overrides
4408		#define'd default value in commproc.h resp.
4409		cpm_8260.h.
4410
4411- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4412  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4413  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4414  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4415  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4416  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4417  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4418  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4419		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4420
4421- CONFIG_PCI_DISABLE_PCIE:
4422		Disable PCI-Express on systems where it is supported but not
4423		required.
4424
4425- CONFIG_PCI_ENUM_ONLY
4426		Only scan through and get the devices on the buses.
4427		Don't do any setup work, presumably because someone or
4428		something has already done it, and we don't need to do it
4429		a second time.	Useful for platforms that are pre-booted
4430		by coreboot or similar.
4431
4432- CONFIG_PCI_INDIRECT_BRIDGE:
4433		Enable support for indirect PCI bridges.
4434
4435- CONFIG_SYS_SRIO:
4436		Chip has SRIO or not
4437
4438- CONFIG_SRIO1:
4439		Board has SRIO 1 port available
4440
4441- CONFIG_SRIO2:
4442		Board has SRIO 2 port available
4443
4444- CONFIG_SRIO_PCIE_BOOT_MASTER
4445		Board can support master function for Boot from SRIO and PCIE
4446
4447- CONFIG_SYS_SRIOn_MEM_VIRT:
4448		Virtual Address of SRIO port 'n' memory region
4449
4450- CONFIG_SYS_SRIOn_MEM_PHYS:
4451		Physical Address of SRIO port 'n' memory region
4452
4453- CONFIG_SYS_SRIOn_MEM_SIZE:
4454		Size of SRIO port 'n' memory region
4455
4456- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4457		Defined to tell the NAND controller that the NAND chip is using
4458		a 16 bit bus.
4459		Not all NAND drivers use this symbol.
4460		Example of drivers that use it:
4461		- drivers/mtd/nand/ndfc.c
4462		- drivers/mtd/nand/mxc_nand.c
4463
4464- CONFIG_SYS_NDFC_EBC0_CFG
4465		Sets the EBC0_CFG register for the NDFC. If not defined
4466		a default value will be used.
4467
4468- CONFIG_SPD_EEPROM
4469		Get DDR timing information from an I2C EEPROM. Common
4470		with pluggable memory modules such as SODIMMs
4471
4472  SPD_EEPROM_ADDRESS
4473		I2C address of the SPD EEPROM
4474
4475- CONFIG_SYS_SPD_BUS_NUM
4476		If SPD EEPROM is on an I2C bus other than the first
4477		one, specify here. Note that the value must resolve
4478		to something your driver can deal with.
4479
4480- CONFIG_SYS_DDR_RAW_TIMING
4481		Get DDR timing information from other than SPD. Common with
4482		soldered DDR chips onboard without SPD. DDR raw timing
4483		parameters are extracted from datasheet and hard-coded into
4484		header files or board specific files.
4485
4486- CONFIG_FSL_DDR_INTERACTIVE
4487		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4488
4489- CONFIG_FSL_DDR_SYNC_REFRESH
4490		Enable sync of refresh for multiple controllers.
4491
4492- CONFIG_FSL_DDR_BIST
4493		Enable built-in memory test for Freescale DDR controllers.
4494
4495- CONFIG_SYS_83XX_DDR_USES_CS0
4496		Only for 83xx systems. If specified, then DDR should
4497		be configured using CS0 and CS1 instead of CS2 and CS3.
4498
4499- CONFIG_ETHER_ON_FEC[12]
4500		Define to enable FEC[12] on a 8xx series processor.
4501
4502- CONFIG_FEC[12]_PHY
4503		Define to the hardcoded PHY address which corresponds
4504		to the given FEC; i. e.
4505			#define CONFIG_FEC1_PHY 4
4506		means that the PHY with address 4 is connected to FEC1
4507
4508		When set to -1, means to probe for first available.
4509
4510- CONFIG_FEC[12]_PHY_NORXERR
4511		The PHY does not have a RXERR line (RMII only).
4512		(so program the FEC to ignore it).
4513
4514- CONFIG_RMII
4515		Enable RMII mode for all FECs.
4516		Note that this is a global option, we can't
4517		have one FEC in standard MII mode and another in RMII mode.
4518
4519- CONFIG_CRC32_VERIFY
4520		Add a verify option to the crc32 command.
4521		The syntax is:
4522
4523		=> crc32 -v <address> <count> <crc32>
4524
4525		Where address/count indicate a memory area
4526		and crc32 is the correct crc32 which the
4527		area should have.
4528
4529- CONFIG_LOOPW
4530		Add the "loopw" memory command. This only takes effect if
4531		the memory commands are activated globally (CONFIG_CMD_MEM).
4532
4533- CONFIG_MX_CYCLIC
4534		Add the "mdc" and "mwc" memory commands. These are cyclic
4535		"md/mw" commands.
4536		Examples:
4537
4538		=> mdc.b 10 4 500
4539		This command will print 4 bytes (10,11,12,13) each 500 ms.
4540
4541		=> mwc.l 100 12345678 10
4542		This command will write 12345678 to address 100 all 10 ms.
4543
4544		This only takes effect if the memory commands are activated
4545		globally (CONFIG_CMD_MEM).
4546
4547- CONFIG_SKIP_LOWLEVEL_INIT
4548		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4549		low level initializations (like setting up the memory
4550		controller) are omitted and/or U-Boot does not
4551		relocate itself into RAM.
4552
4553		Normally this variable MUST NOT be defined. The only
4554		exception is when U-Boot is loaded (to RAM) by some
4555		other boot loader or by a debugger which performs
4556		these initializations itself.
4557
4558- CONFIG_SKIP_LOWLEVEL_INIT_ONLY
4559		[ARM926EJ-S only] This allows just the call to lowlevel_init()
4560		to be skipped. The normal CP15 init (such as enabling the
4561		instruction cache) is still performed.
4562
4563- CONFIG_SPL_BUILD
4564		Modifies the behaviour of start.S when compiling a loader
4565		that is executed before the actual U-Boot. E.g. when
4566		compiling a NAND SPL.
4567
4568- CONFIG_TPL_BUILD
4569		Modifies the behaviour of start.S  when compiling a loader
4570		that is executed after the SPL and before the actual U-Boot.
4571		It is loaded by the SPL.
4572
4573- CONFIG_SYS_MPC85XX_NO_RESETVEC
4574		Only for 85xx systems. If this variable is specified, the section
4575		.resetvec is not kept and the section .bootpg is placed in the
4576		previous 4k of the .text section.
4577
4578- CONFIG_ARCH_MAP_SYSMEM
4579		Generally U-Boot (and in particular the md command) uses
4580		effective address. It is therefore not necessary to regard
4581		U-Boot address as virtual addresses that need to be translated
4582		to physical addresses. However, sandbox requires this, since
4583		it maintains its own little RAM buffer which contains all
4584		addressable memory. This option causes some memory accesses
4585		to be mapped through map_sysmem() / unmap_sysmem().
4586
4587- CONFIG_X86_RESET_VECTOR
4588		If defined, the x86 reset vector code is included. This is not
4589		needed when U-Boot is running from Coreboot.
4590
4591- CONFIG_SYS_MPUCLK
4592		Defines the MPU clock speed (in MHz).
4593
4594		NOTE : currently only supported on AM335x platforms.
4595
4596- CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
4597		Enables the RTC32K OSC on AM33xx based plattforms
4598
4599- CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
4600		Option to disable subpage write in NAND driver
4601		driver that uses this:
4602		drivers/mtd/nand/davinci_nand.c
4603
4604Freescale QE/FMAN Firmware Support:
4605-----------------------------------
4606
4607The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4608loading of "firmware", which is encoded in the QE firmware binary format.
4609This firmware often needs to be loaded during U-Boot booting, so macros
4610are used to identify the storage device (NOR flash, SPI, etc) and the address
4611within that device.
4612
4613- CONFIG_SYS_FMAN_FW_ADDR
4614	The address in the storage device where the FMAN microcode is located.  The
4615	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4616	is also specified.
4617
4618- CONFIG_SYS_QE_FW_ADDR
4619	The address in the storage device where the QE microcode is located.  The
4620	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4621	is also specified.
4622
4623- CONFIG_SYS_QE_FMAN_FW_LENGTH
4624	The maximum possible size of the firmware.  The firmware binary format
4625	has a field that specifies the actual size of the firmware, but it
4626	might not be possible to read any part of the firmware unless some
4627	local storage is allocated to hold the entire firmware first.
4628
4629- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4630	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4631	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4632	virtual address in NOR flash.
4633
4634- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4635	Specifies that QE/FMAN firmware is located in NAND flash.
4636	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4637
4638- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4639	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4640	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4641
4642- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4643	Specifies that QE/FMAN firmware is located in the remote (master)
4644	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4645	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4646	window->master inbound window->master LAW->the ucode address in
4647	master's memory space.
4648
4649Freescale Layerscape Management Complex Firmware Support:
4650---------------------------------------------------------
4651The Freescale Layerscape Management Complex (MC) supports the loading of
4652"firmware".
4653This firmware often needs to be loaded during U-Boot booting, so macros
4654are used to identify the storage device (NOR flash, SPI, etc) and the address
4655within that device.
4656
4657- CONFIG_FSL_MC_ENET
4658	Enable the MC driver for Layerscape SoCs.
4659
4660Freescale Layerscape Debug Server Support:
4661-------------------------------------------
4662The Freescale Layerscape Debug Server Support supports the loading of
4663"Debug Server firmware" and triggering SP boot-rom.
4664This firmware often needs to be loaded during U-Boot booting.
4665
4666- CONFIG_SYS_MC_RSV_MEM_ALIGN
4667	Define alignment of reserved memory MC requires
4668
4669Reproducible builds
4670-------------------
4671
4672In order to achieve reproducible builds, timestamps used in the U-Boot build
4673process have to be set to a fixed value.
4674
4675This is done using the SOURCE_DATE_EPOCH environment variable.
4676SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
4677option for U-Boot or an environment variable in U-Boot.
4678
4679SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
4680
4681Building the Software:
4682======================
4683
4684Building U-Boot has been tested in several native build environments
4685and in many different cross environments. Of course we cannot support
4686all possibly existing versions of cross development tools in all
4687(potentially obsolete) versions. In case of tool chain problems we
4688recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4689which is extensively used to build and test U-Boot.
4690
4691If you are not using a native environment, it is assumed that you
4692have GNU cross compiling tools available in your path. In this case,
4693you must set the environment variable CROSS_COMPILE in your shell.
4694Note that no changes to the Makefile or any other source files are
4695necessary. For example using the ELDK on a 4xx CPU, please enter:
4696
4697	$ CROSS_COMPILE=ppc_4xx-
4698	$ export CROSS_COMPILE
4699
4700Note: If you wish to generate Windows versions of the utilities in
4701      the tools directory you can use the MinGW toolchain
4702      (http://www.mingw.org).  Set your HOST tools to the MinGW
4703      toolchain and execute 'make tools'.  For example:
4704
4705       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4706
4707      Binaries such as tools/mkimage.exe will be created which can
4708      be executed on computers running Windows.
4709
4710U-Boot is intended to be simple to build. After installing the
4711sources you must configure U-Boot for one specific board type. This
4712is done by typing:
4713
4714	make NAME_defconfig
4715
4716where "NAME_defconfig" is the name of one of the existing configu-
4717rations; see boards.cfg for supported names.
4718
4719Note: for some board special configuration names may exist; check if
4720      additional information is available from the board vendor; for
4721      instance, the TQM823L systems are available without (standard)
4722      or with LCD support. You can select such additional "features"
4723      when choosing the configuration, i. e.
4724
4725      make TQM823L_defconfig
4726	- will configure for a plain TQM823L, i. e. no LCD support
4727
4728      make TQM823L_LCD_defconfig
4729	- will configure for a TQM823L with U-Boot console on LCD
4730
4731      etc.
4732
4733
4734Finally, type "make all", and you should get some working U-Boot
4735images ready for download to / installation on your system:
4736
4737- "u-boot.bin" is a raw binary image
4738- "u-boot" is an image in ELF binary format
4739- "u-boot.srec" is in Motorola S-Record format
4740
4741By default the build is performed locally and the objects are saved
4742in the source directory. One of the two methods can be used to change
4743this behavior and build U-Boot to some external directory:
4744
47451. Add O= to the make command line invocations:
4746
4747	make O=/tmp/build distclean
4748	make O=/tmp/build NAME_defconfig
4749	make O=/tmp/build all
4750
47512. Set environment variable KBUILD_OUTPUT to point to the desired location:
4752
4753	export KBUILD_OUTPUT=/tmp/build
4754	make distclean
4755	make NAME_defconfig
4756	make all
4757
4758Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
4759variable.
4760
4761
4762Please be aware that the Makefiles assume you are using GNU make, so
4763for instance on NetBSD you might need to use "gmake" instead of
4764native "make".
4765
4766
4767If the system board that you have is not listed, then you will need
4768to port U-Boot to your hardware platform. To do this, follow these
4769steps:
4770
47711.  Create a new directory to hold your board specific code. Add any
4772    files you need. In your board directory, you will need at least
4773    the "Makefile" and a "<board>.c".
47742.  Create a new configuration file "include/configs/<board>.h" for
4775    your board.
47763.  If you're porting U-Boot to a new CPU, then also create a new
4777    directory to hold your CPU specific code. Add any files you need.
47784.  Run "make <board>_defconfig" with your new name.
47795.  Type "make", and you should get a working "u-boot.srec" file
4780    to be installed on your target system.
47816.  Debug and solve any problems that might arise.
4782    [Of course, this last step is much harder than it sounds.]
4783
4784
4785Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4786==============================================================
4787
4788If you have modified U-Boot sources (for instance added a new board
4789or support for new devices, a new CPU, etc.) you are expected to
4790provide feedback to the other developers. The feedback normally takes
4791the form of a "patch", i. e. a context diff against a certain (latest
4792official or latest in the git repository) version of U-Boot sources.
4793
4794But before you submit such a patch, please verify that your modifi-
4795cation did not break existing code. At least make sure that *ALL* of
4796the supported boards compile WITHOUT ANY compiler warnings. To do so,
4797just run the buildman script (tools/buildman/buildman), which will
4798configure and build U-Boot for ALL supported system. Be warned, this
4799will take a while. Please see the buildman README, or run 'buildman -H'
4800for documentation.
4801
4802
4803See also "U-Boot Porting Guide" below.
4804
4805
4806Monitor Commands - Overview:
4807============================
4808
4809go	- start application at address 'addr'
4810run	- run commands in an environment variable
4811bootm	- boot application image from memory
4812bootp	- boot image via network using BootP/TFTP protocol
4813bootz   - boot zImage from memory
4814tftpboot- boot image via network using TFTP protocol
4815	       and env variables "ipaddr" and "serverip"
4816	       (and eventually "gatewayip")
4817tftpput - upload a file via network using TFTP protocol
4818rarpboot- boot image via network using RARP/TFTP protocol
4819diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4820loads	- load S-Record file over serial line
4821loadb	- load binary file over serial line (kermit mode)
4822md	- memory display
4823mm	- memory modify (auto-incrementing)
4824nm	- memory modify (constant address)
4825mw	- memory write (fill)
4826cp	- memory copy
4827cmp	- memory compare
4828crc32	- checksum calculation
4829i2c	- I2C sub-system
4830sspi	- SPI utility commands
4831base	- print or set address offset
4832printenv- print environment variables
4833setenv	- set environment variables
4834saveenv - save environment variables to persistent storage
4835protect - enable or disable FLASH write protection
4836erase	- erase FLASH memory
4837flinfo	- print FLASH memory information
4838nand	- NAND memory operations (see doc/README.nand)
4839bdinfo	- print Board Info structure
4840iminfo	- print header information for application image
4841coninfo - print console devices and informations
4842ide	- IDE sub-system
4843loop	- infinite loop on address range
4844loopw	- infinite write loop on address range
4845mtest	- simple RAM test
4846icache	- enable or disable instruction cache
4847dcache	- enable or disable data cache
4848reset	- Perform RESET of the CPU
4849echo	- echo args to console
4850version - print monitor version
4851help	- print online help
4852?	- alias for 'help'
4853
4854
4855Monitor Commands - Detailed Description:
4856========================================
4857
4858TODO.
4859
4860For now: just type "help <command>".
4861
4862
4863Environment Variables:
4864======================
4865
4866U-Boot supports user configuration using Environment Variables which
4867can be made persistent by saving to Flash memory.
4868
4869Environment Variables are set using "setenv", printed using
4870"printenv", and saved to Flash using "saveenv". Using "setenv"
4871without a value can be used to delete a variable from the
4872environment. As long as you don't save the environment you are
4873working with an in-memory copy. In case the Flash area containing the
4874environment is erased by accident, a default environment is provided.
4875
4876Some configuration options can be set using Environment Variables.
4877
4878List of environment variables (most likely not complete):
4879
4880  baudrate	- see CONFIG_BAUDRATE
4881
4882  bootdelay	- see CONFIG_BOOTDELAY
4883
4884  bootcmd	- see CONFIG_BOOTCOMMAND
4885
4886  bootargs	- Boot arguments when booting an RTOS image
4887
4888  bootfile	- Name of the image to load with TFTP
4889
4890  bootm_low	- Memory range available for image processing in the bootm
4891		  command can be restricted. This variable is given as
4892		  a hexadecimal number and defines lowest address allowed
4893		  for use by the bootm command. See also "bootm_size"
4894		  environment variable. Address defined by "bootm_low" is
4895		  also the base of the initial memory mapping for the Linux
4896		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
4897		  bootm_mapsize.
4898
4899  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
4900		  This variable is given as a hexadecimal number and it
4901		  defines the size of the memory region starting at base
4902		  address bootm_low that is accessible by the Linux kernel
4903		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
4904		  as the default value if it is defined, and bootm_size is
4905		  used otherwise.
4906
4907  bootm_size	- Memory range available for image processing in the bootm
4908		  command can be restricted. This variable is given as
4909		  a hexadecimal number and defines the size of the region
4910		  allowed for use by the bootm command. See also "bootm_low"
4911		  environment variable.
4912
4913  updatefile	- Location of the software update file on a TFTP server, used
4914		  by the automatic software update feature. Please refer to
4915		  documentation in doc/README.update for more details.
4916
4917  autoload	- if set to "no" (any string beginning with 'n'),
4918		  "bootp" will just load perform a lookup of the
4919		  configuration from the BOOTP server, but not try to
4920		  load any image using TFTP
4921
4922  autostart	- if set to "yes", an image loaded using the "bootp",
4923		  "rarpboot", "tftpboot" or "diskboot" commands will
4924		  be automatically started (by internally calling
4925		  "bootm")
4926
4927		  If set to "no", a standalone image passed to the
4928		  "bootm" command will be copied to the load address
4929		  (and eventually uncompressed), but NOT be started.
4930		  This can be used to load and uncompress arbitrary
4931		  data.
4932
4933  fdt_high	- if set this restricts the maximum address that the
4934		  flattened device tree will be copied into upon boot.
4935		  For example, if you have a system with 1 GB memory
4936		  at physical address 0x10000000, while Linux kernel
4937		  only recognizes the first 704 MB as low memory, you
4938		  may need to set fdt_high as 0x3C000000 to have the
4939		  device tree blob be copied to the maximum address
4940		  of the 704 MB low memory, so that Linux kernel can
4941		  access it during the boot procedure.
4942
4943		  If this is set to the special value 0xFFFFFFFF then
4944		  the fdt will not be copied at all on boot.  For this
4945		  to work it must reside in writable memory, have
4946		  sufficient padding on the end of it for u-boot to
4947		  add the information it needs into it, and the memory
4948		  must be accessible by the kernel.
4949
4950  fdtcontroladdr- if set this is the address of the control flattened
4951		  device tree used by U-Boot when CONFIG_OF_CONTROL is
4952		  defined.
4953
4954  i2cfast	- (PPC405GP|PPC405EP only)
4955		  if set to 'y' configures Linux I2C driver for fast
4956		  mode (400kHZ). This environment variable is used in
4957		  initialization code. So, for changes to be effective
4958		  it must be saved and board must be reset.
4959
4960  initrd_high	- restrict positioning of initrd images:
4961		  If this variable is not set, initrd images will be
4962		  copied to the highest possible address in RAM; this
4963		  is usually what you want since it allows for
4964		  maximum initrd size. If for some reason you want to
4965		  make sure that the initrd image is loaded below the
4966		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
4967		  variable to a value of "no" or "off" or "0".
4968		  Alternatively, you can set it to a maximum upper
4969		  address to use (U-Boot will still check that it
4970		  does not overwrite the U-Boot stack and data).
4971
4972		  For instance, when you have a system with 16 MB
4973		  RAM, and want to reserve 4 MB from use by Linux,
4974		  you can do this by adding "mem=12M" to the value of
4975		  the "bootargs" variable. However, now you must make
4976		  sure that the initrd image is placed in the first
4977		  12 MB as well - this can be done with
4978
4979		  setenv initrd_high 00c00000
4980
4981		  If you set initrd_high to 0xFFFFFFFF, this is an
4982		  indication to U-Boot that all addresses are legal
4983		  for the Linux kernel, including addresses in flash
4984		  memory. In this case U-Boot will NOT COPY the
4985		  ramdisk at all. This may be useful to reduce the
4986		  boot time on your system, but requires that this
4987		  feature is supported by your Linux kernel.
4988
4989  ipaddr	- IP address; needed for tftpboot command
4990
4991  loadaddr	- Default load address for commands like "bootp",
4992		  "rarpboot", "tftpboot", "loadb" or "diskboot"
4993
4994  loads_echo	- see CONFIG_LOADS_ECHO
4995
4996  serverip	- TFTP server IP address; needed for tftpboot command
4997
4998  bootretry	- see CONFIG_BOOT_RETRY_TIME
4999
5000  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
5001
5002  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
5003
5004  ethprime	- controls which interface is used first.
5005
5006  ethact	- controls which interface is currently active.
5007		  For example you can do the following
5008
5009		  => setenv ethact FEC
5010		  => ping 192.168.0.1 # traffic sent on FEC
5011		  => setenv ethact SCC
5012		  => ping 10.0.0.1 # traffic sent on SCC
5013
5014  ethrotate	- When set to "no" U-Boot does not go through all
5015		  available network interfaces.
5016		  It just stays at the currently selected interface.
5017
5018  netretry	- When set to "no" each network operation will
5019		  either succeed or fail without retrying.
5020		  When set to "once" the network operation will
5021		  fail when all the available network interfaces
5022		  are tried once without success.
5023		  Useful on scripts which control the retry operation
5024		  themselves.
5025
5026  npe_ucode	- set load address for the NPE microcode
5027
5028  silent_linux  - If set then Linux will be told to boot silently, by
5029		  changing the console to be empty. If "yes" it will be
5030		  made silent. If "no" it will not be made silent. If
5031		  unset, then it will be made silent if the U-Boot console
5032		  is silent.
5033
5034  tftpsrcp	- If this is set, the value is used for TFTP's
5035		  UDP source port.
5036
5037  tftpdstp	- If this is set, the value is used for TFTP's UDP
5038		  destination port instead of the Well Know Port 69.
5039
5040  tftpblocksize - Block size to use for TFTP transfers; if not set,
5041		  we use the TFTP server's default block size
5042
5043  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
5044		  seconds, minimum value is 1000 = 1 second). Defines
5045		  when a packet is considered to be lost so it has to
5046		  be retransmitted. The default is 5000 = 5 seconds.
5047		  Lowering this value may make downloads succeed
5048		  faster in networks with high packet loss rates or
5049		  with unreliable TFTP servers.
5050
5051  tftptimeoutcountmax	- maximum count of TFTP timeouts (no
5052		  unit, minimum value = 0). Defines how many timeouts
5053		  can happen during a single file transfer before that
5054		  transfer is aborted. The default is 10, and 0 means
5055		  'no timeouts allowed'. Increasing this value may help
5056		  downloads succeed with high packet loss rates, or with
5057		  unreliable TFTP servers or client hardware.
5058
5059  vlan		- When set to a value < 4095 the traffic over
5060		  Ethernet is encapsulated/received over 802.1q
5061		  VLAN tagged frames.
5062
5063  bootpretryperiod	- Period during which BOOTP/DHCP sends retries.
5064		  Unsigned value, in milliseconds. If not set, the period will
5065		  be either the default (28000), or a value based on
5066		  CONFIG_NET_RETRY_COUNT, if defined. This value has
5067		  precedence over the valu based on CONFIG_NET_RETRY_COUNT.
5068
5069The following image location variables contain the location of images
5070used in booting. The "Image" column gives the role of the image and is
5071not an environment variable name. The other columns are environment
5072variable names. "File Name" gives the name of the file on a TFTP
5073server, "RAM Address" gives the location in RAM the image will be
5074loaded to, and "Flash Location" gives the image's address in NOR
5075flash or offset in NAND flash.
5076
5077*Note* - these variables don't have to be defined for all boards, some
5078boards currently use other variables for these purposes, and some
5079boards use these variables for other purposes.
5080
5081Image		    File Name	     RAM Address       Flash Location
5082-----		    ---------	     -----------       --------------
5083u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
5084Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
5085device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
5086ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
5087
5088The following environment variables may be used and automatically
5089updated by the network boot commands ("bootp" and "rarpboot"),
5090depending the information provided by your boot server:
5091
5092  bootfile	- see above
5093  dnsip		- IP address of your Domain Name Server
5094  dnsip2	- IP address of your secondary Domain Name Server
5095  gatewayip	- IP address of the Gateway (Router) to use
5096  hostname	- Target hostname
5097  ipaddr	- see above
5098  netmask	- Subnet Mask
5099  rootpath	- Pathname of the root filesystem on the NFS server
5100  serverip	- see above
5101
5102
5103There are two special Environment Variables:
5104
5105  serial#	- contains hardware identification information such
5106		  as type string and/or serial number
5107  ethaddr	- Ethernet address
5108
5109These variables can be set only once (usually during manufacturing of
5110the board). U-Boot refuses to delete or overwrite these variables
5111once they have been set once.
5112
5113
5114Further special Environment Variables:
5115
5116  ver		- Contains the U-Boot version string as printed
5117		  with the "version" command. This variable is
5118		  readonly (see CONFIG_VERSION_VARIABLE).
5119
5120
5121Please note that changes to some configuration parameters may take
5122only effect after the next boot (yes, that's just like Windoze :-).
5123
5124
5125Callback functions for environment variables:
5126---------------------------------------------
5127
5128For some environment variables, the behavior of u-boot needs to change
5129when their values are changed.  This functionality allows functions to
5130be associated with arbitrary variables.  On creation, overwrite, or
5131deletion, the callback will provide the opportunity for some side
5132effect to happen or for the change to be rejected.
5133
5134The callbacks are named and associated with a function using the
5135U_BOOT_ENV_CALLBACK macro in your board or driver code.
5136
5137These callbacks are associated with variables in one of two ways.  The
5138static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
5139in the board configuration to a string that defines a list of
5140associations.  The list must be in the following format:
5141
5142	entry = variable_name[:callback_name]
5143	list = entry[,list]
5144
5145If the callback name is not specified, then the callback is deleted.
5146Spaces are also allowed anywhere in the list.
5147
5148Callbacks can also be associated by defining the ".callbacks" variable
5149with the same list format above.  Any association in ".callbacks" will
5150override any association in the static list. You can define
5151CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
5152".callbacks" environment variable in the default or embedded environment.
5153
5154If CONFIG_REGEX is defined, the variable_name above is evaluated as a
5155regular expression. This allows multiple variables to be connected to
5156the same callback without explicitly listing them all out.
5157
5158
5159Command Line Parsing:
5160=====================
5161
5162There are two different command line parsers available with U-Boot:
5163the old "simple" one, and the much more powerful "hush" shell:
5164
5165Old, simple command line parser:
5166--------------------------------
5167
5168- supports environment variables (through setenv / saveenv commands)
5169- several commands on one line, separated by ';'
5170- variable substitution using "... ${name} ..." syntax
5171- special characters ('$', ';') can be escaped by prefixing with '\',
5172  for example:
5173	setenv bootcmd bootm \${address}
5174- You can also escape text by enclosing in single apostrophes, for example:
5175	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
5176
5177Hush shell:
5178-----------
5179
5180- similar to Bourne shell, with control structures like
5181  if...then...else...fi, for...do...done; while...do...done,
5182  until...do...done, ...
5183- supports environment ("global") variables (through setenv / saveenv
5184  commands) and local shell variables (through standard shell syntax
5185  "name=value"); only environment variables can be used with "run"
5186  command
5187
5188General rules:
5189--------------
5190
5191(1) If a command line (or an environment variable executed by a "run"
5192    command) contains several commands separated by semicolon, and
5193    one of these commands fails, then the remaining commands will be
5194    executed anyway.
5195
5196(2) If you execute several variables with one call to run (i. e.
5197    calling run with a list of variables as arguments), any failing
5198    command will cause "run" to terminate, i. e. the remaining
5199    variables are not executed.
5200
5201Note for Redundant Ethernet Interfaces:
5202=======================================
5203
5204Some boards come with redundant Ethernet interfaces; U-Boot supports
5205such configurations and is capable of automatic selection of a
5206"working" interface when needed. MAC assignment works as follows:
5207
5208Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
5209MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
5210"eth1addr" (=>eth1), "eth2addr", ...
5211
5212If the network interface stores some valid MAC address (for instance
5213in SROM), this is used as default address if there is NO correspon-
5214ding setting in the environment; if the corresponding environment
5215variable is set, this overrides the settings in the card; that means:
5216
5217o If the SROM has a valid MAC address, and there is no address in the
5218  environment, the SROM's address is used.
5219
5220o If there is no valid address in the SROM, and a definition in the
5221  environment exists, then the value from the environment variable is
5222  used.
5223
5224o If both the SROM and the environment contain a MAC address, and
5225  both addresses are the same, this MAC address is used.
5226
5227o If both the SROM and the environment contain a MAC address, and the
5228  addresses differ, the value from the environment is used and a
5229  warning is printed.
5230
5231o If neither SROM nor the environment contain a MAC address, an error
5232  is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
5233  a random, locally-assigned MAC is used.
5234
5235If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
5236will be programmed into hardware as part of the initialization process.	 This
5237may be skipped by setting the appropriate 'ethmacskip' environment variable.
5238The naming convention is as follows:
5239"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
5240
5241Image Formats:
5242==============
5243
5244U-Boot is capable of booting (and performing other auxiliary operations on)
5245images in two formats:
5246
5247New uImage format (FIT)
5248-----------------------
5249
5250Flexible and powerful format based on Flattened Image Tree -- FIT (similar
5251to Flattened Device Tree). It allows the use of images with multiple
5252components (several kernels, ramdisks, etc.), with contents protected by
5253SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
5254
5255
5256Old uImage format
5257-----------------
5258
5259Old image format is based on binary files which can be basically anything,
5260preceded by a special header; see the definitions in include/image.h for
5261details; basically, the header defines the following image properties:
5262
5263* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
5264  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
5265  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
5266  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
5267  INTEGRITY).
5268* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
5269  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
5270  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
5271* Compression Type (uncompressed, gzip, bzip2)
5272* Load Address
5273* Entry Point
5274* Image Name
5275* Image Timestamp
5276
5277The header is marked by a special Magic Number, and both the header
5278and the data portions of the image are secured against corruption by
5279CRC32 checksums.
5280
5281
5282Linux Support:
5283==============
5284
5285Although U-Boot should support any OS or standalone application
5286easily, the main focus has always been on Linux during the design of
5287U-Boot.
5288
5289U-Boot includes many features that so far have been part of some
5290special "boot loader" code within the Linux kernel. Also, any
5291"initrd" images to be used are no longer part of one big Linux image;
5292instead, kernel and "initrd" are separate images. This implementation
5293serves several purposes:
5294
5295- the same features can be used for other OS or standalone
5296  applications (for instance: using compressed images to reduce the
5297  Flash memory footprint)
5298
5299- it becomes much easier to port new Linux kernel versions because
5300  lots of low-level, hardware dependent stuff are done by U-Boot
5301
5302- the same Linux kernel image can now be used with different "initrd"
5303  images; of course this also means that different kernel images can
5304  be run with the same "initrd". This makes testing easier (you don't
5305  have to build a new "zImage.initrd" Linux image when you just
5306  change a file in your "initrd"). Also, a field-upgrade of the
5307  software is easier now.
5308
5309
5310Linux HOWTO:
5311============
5312
5313Porting Linux to U-Boot based systems:
5314---------------------------------------
5315
5316U-Boot cannot save you from doing all the necessary modifications to
5317configure the Linux device drivers for use with your target hardware
5318(no, we don't intend to provide a full virtual machine interface to
5319Linux :-).
5320
5321But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
5322
5323Just make sure your machine specific header file (for instance
5324include/asm-ppc/tqm8xx.h) includes the same definition of the Board
5325Information structure as we define in include/asm-<arch>/u-boot.h,
5326and make sure that your definition of IMAP_ADDR uses the same value
5327as your U-Boot configuration in CONFIG_SYS_IMMR.
5328
5329Note that U-Boot now has a driver model, a unified model for drivers.
5330If you are adding a new driver, plumb it into driver model. If there
5331is no uclass available, you are encouraged to create one. See
5332doc/driver-model.
5333
5334
5335Configuring the Linux kernel:
5336-----------------------------
5337
5338No specific requirements for U-Boot. Make sure you have some root
5339device (initial ramdisk, NFS) for your target system.
5340
5341
5342Building a Linux Image:
5343-----------------------
5344
5345With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5346not used. If you use recent kernel source, a new build target
5347"uImage" will exist which automatically builds an image usable by
5348U-Boot. Most older kernels also have support for a "pImage" target,
5349which was introduced for our predecessor project PPCBoot and uses a
5350100% compatible format.
5351
5352Example:
5353
5354	make TQM850L_defconfig
5355	make oldconfig
5356	make dep
5357	make uImage
5358
5359The "uImage" build target uses a special tool (in 'tools/mkimage') to
5360encapsulate a compressed Linux kernel image with header	 information,
5361CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5362
5363* build a standard "vmlinux" kernel image (in ELF binary format):
5364
5365* convert the kernel into a raw binary image:
5366
5367	${CROSS_COMPILE}-objcopy -O binary \
5368				 -R .note -R .comment \
5369				 -S vmlinux linux.bin
5370
5371* compress the binary image:
5372
5373	gzip -9 linux.bin
5374
5375* package compressed binary image for U-Boot:
5376
5377	mkimage -A ppc -O linux -T kernel -C gzip \
5378		-a 0 -e 0 -n "Linux Kernel Image" \
5379		-d linux.bin.gz uImage
5380
5381
5382The "mkimage" tool can also be used to create ramdisk images for use
5383with U-Boot, either separated from the Linux kernel image, or
5384combined into one file. "mkimage" encapsulates the images with a 64
5385byte header containing information about target architecture,
5386operating system, image type, compression method, entry points, time
5387stamp, CRC32 checksums, etc.
5388
5389"mkimage" can be called in two ways: to verify existing images and
5390print the header information, or to build new images.
5391
5392In the first form (with "-l" option) mkimage lists the information
5393contained in the header of an existing U-Boot image; this includes
5394checksum verification:
5395
5396	tools/mkimage -l image
5397	  -l ==> list image header information
5398
5399The second form (with "-d" option) is used to build a U-Boot image
5400from a "data file" which is used as image payload:
5401
5402	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5403		      -n name -d data_file image
5404	  -A ==> set architecture to 'arch'
5405	  -O ==> set operating system to 'os'
5406	  -T ==> set image type to 'type'
5407	  -C ==> set compression type 'comp'
5408	  -a ==> set load address to 'addr' (hex)
5409	  -e ==> set entry point to 'ep' (hex)
5410	  -n ==> set image name to 'name'
5411	  -d ==> use image data from 'datafile'
5412
5413Right now, all Linux kernels for PowerPC systems use the same load
5414address (0x00000000), but the entry point address depends on the
5415kernel version:
5416
5417- 2.2.x kernels have the entry point at 0x0000000C,
5418- 2.3.x and later kernels have the entry point at 0x00000000.
5419
5420So a typical call to build a U-Boot image would read:
5421
5422	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5423	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5424	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5425	> examples/uImage.TQM850L
5426	Image Name:   2.4.4 kernel for TQM850L
5427	Created:      Wed Jul 19 02:34:59 2000
5428	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5429	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5430	Load Address: 0x00000000
5431	Entry Point:  0x00000000
5432
5433To verify the contents of the image (or check for corruption):
5434
5435	-> tools/mkimage -l examples/uImage.TQM850L
5436	Image Name:   2.4.4 kernel for TQM850L
5437	Created:      Wed Jul 19 02:34:59 2000
5438	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5439	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5440	Load Address: 0x00000000
5441	Entry Point:  0x00000000
5442
5443NOTE: for embedded systems where boot time is critical you can trade
5444speed for memory and install an UNCOMPRESSED image instead: this
5445needs more space in Flash, but boots much faster since it does not
5446need to be uncompressed:
5447
5448	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5449	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5450	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5451	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5452	> examples/uImage.TQM850L-uncompressed
5453	Image Name:   2.4.4 kernel for TQM850L
5454	Created:      Wed Jul 19 02:34:59 2000
5455	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5456	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5457	Load Address: 0x00000000
5458	Entry Point:  0x00000000
5459
5460
5461Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5462when your kernel is intended to use an initial ramdisk:
5463
5464	-> tools/mkimage -n 'Simple Ramdisk Image' \
5465	> -A ppc -O linux -T ramdisk -C gzip \
5466	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5467	Image Name:   Simple Ramdisk Image
5468	Created:      Wed Jan 12 14:01:50 2000
5469	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5470	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5471	Load Address: 0x00000000
5472	Entry Point:  0x00000000
5473
5474The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
5475option performs the converse operation of the mkimage's second form (the "-d"
5476option). Given an image built by mkimage, the dumpimage extracts a "data file"
5477from the image:
5478
5479	tools/dumpimage -i image -T type -p position data_file
5480	  -i ==> extract from the 'image' a specific 'data_file'
5481	  -T ==> set image type to 'type'
5482	  -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image'
5483
5484
5485Installing a Linux Image:
5486-------------------------
5487
5488To downloading a U-Boot image over the serial (console) interface,
5489you must convert the image to S-Record format:
5490
5491	objcopy -I binary -O srec examples/image examples/image.srec
5492
5493The 'objcopy' does not understand the information in the U-Boot
5494image header, so the resulting S-Record file will be relative to
5495address 0x00000000. To load it to a given address, you need to
5496specify the target address as 'offset' parameter with the 'loads'
5497command.
5498
5499Example: install the image to address 0x40100000 (which on the
5500TQM8xxL is in the first Flash bank):
5501
5502	=> erase 40100000 401FFFFF
5503
5504	.......... done
5505	Erased 8 sectors
5506
5507	=> loads 40100000
5508	## Ready for S-Record download ...
5509	~>examples/image.srec
5510	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5511	...
5512	15989 15990 15991 15992
5513	[file transfer complete]
5514	[connected]
5515	## Start Addr = 0x00000000
5516
5517
5518You can check the success of the download using the 'iminfo' command;
5519this includes a checksum verification so you can be sure no data
5520corruption happened:
5521
5522	=> imi 40100000
5523
5524	## Checking Image at 40100000 ...
5525	   Image Name:	 2.2.13 for initrd on TQM850L
5526	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5527	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5528	   Load Address: 00000000
5529	   Entry Point:	 0000000c
5530	   Verifying Checksum ... OK
5531
5532
5533Boot Linux:
5534-----------
5535
5536The "bootm" command is used to boot an application that is stored in
5537memory (RAM or Flash). In case of a Linux kernel image, the contents
5538of the "bootargs" environment variable is passed to the kernel as
5539parameters. You can check and modify this variable using the
5540"printenv" and "setenv" commands:
5541
5542
5543	=> printenv bootargs
5544	bootargs=root=/dev/ram
5545
5546	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5547
5548	=> printenv bootargs
5549	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5550
5551	=> bootm 40020000
5552	## Booting Linux kernel at 40020000 ...
5553	   Image Name:	 2.2.13 for NFS on TQM850L
5554	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5555	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5556	   Load Address: 00000000
5557	   Entry Point:	 0000000c
5558	   Verifying Checksum ... OK
5559	   Uncompressing Kernel Image ... OK
5560	Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:35:17 MEST 2000
5561	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5562	time_init: decrementer frequency = 187500000/60
5563	Calibrating delay loop... 49.77 BogoMIPS
5564	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5565	...
5566
5567If you want to boot a Linux kernel with initial RAM disk, you pass
5568the memory addresses of both the kernel and the initrd image (PPBCOOT
5569format!) to the "bootm" command:
5570
5571	=> imi 40100000 40200000
5572
5573	## Checking Image at 40100000 ...
5574	   Image Name:	 2.2.13 for initrd on TQM850L
5575	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5576	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5577	   Load Address: 00000000
5578	   Entry Point:	 0000000c
5579	   Verifying Checksum ... OK
5580
5581	## Checking Image at 40200000 ...
5582	   Image Name:	 Simple Ramdisk Image
5583	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5584	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5585	   Load Address: 00000000
5586	   Entry Point:	 00000000
5587	   Verifying Checksum ... OK
5588
5589	=> bootm 40100000 40200000
5590	## Booting Linux kernel at 40100000 ...
5591	   Image Name:	 2.2.13 for initrd on TQM850L
5592	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5593	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5594	   Load Address: 00000000
5595	   Entry Point:	 0000000c
5596	   Verifying Checksum ... OK
5597	   Uncompressing Kernel Image ... OK
5598	## Loading RAMDisk Image at 40200000 ...
5599	   Image Name:	 Simple Ramdisk Image
5600	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5601	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5602	   Load Address: 00000000
5603	   Entry Point:	 00000000
5604	   Verifying Checksum ... OK
5605	   Loading Ramdisk ... OK
5606	Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:32:08 MEST 2000
5607	Boot arguments: root=/dev/ram
5608	time_init: decrementer frequency = 187500000/60
5609	Calibrating delay loop... 49.77 BogoMIPS
5610	...
5611	RAMDISK: Compressed image found at block 0
5612	VFS: Mounted root (ext2 filesystem).
5613
5614	bash#
5615
5616Boot Linux and pass a flat device tree:
5617-----------
5618
5619First, U-Boot must be compiled with the appropriate defines. See the section
5620titled "Linux Kernel Interface" above for a more in depth explanation. The
5621following is an example of how to start a kernel and pass an updated
5622flat device tree:
5623
5624=> print oftaddr
5625oftaddr=0x300000
5626=> print oft
5627oft=oftrees/mpc8540ads.dtb
5628=> tftp $oftaddr $oft
5629Speed: 1000, full duplex
5630Using TSEC0 device
5631TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5632Filename 'oftrees/mpc8540ads.dtb'.
5633Load address: 0x300000
5634Loading: #
5635done
5636Bytes transferred = 4106 (100a hex)
5637=> tftp $loadaddr $bootfile
5638Speed: 1000, full duplex
5639Using TSEC0 device
5640TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5641Filename 'uImage'.
5642Load address: 0x200000
5643Loading:############
5644done
5645Bytes transferred = 1029407 (fb51f hex)
5646=> print loadaddr
5647loadaddr=200000
5648=> print oftaddr
5649oftaddr=0x300000
5650=> bootm $loadaddr - $oftaddr
5651## Booting image at 00200000 ...
5652   Image Name:	 Linux-2.6.17-dirty
5653   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5654   Data Size:	 1029343 Bytes = 1005.2 kB
5655   Load Address: 00000000
5656   Entry Point:	 00000000
5657   Verifying Checksum ... OK
5658   Uncompressing Kernel Image ... OK
5659Booting using flat device tree at 0x300000
5660Using MPC85xx ADS machine description
5661Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5662[snip]
5663
5664
5665More About U-Boot Image Types:
5666------------------------------
5667
5668U-Boot supports the following image types:
5669
5670   "Standalone Programs" are directly runnable in the environment
5671	provided by U-Boot; it is expected that (if they behave
5672	well) you can continue to work in U-Boot after return from
5673	the Standalone Program.
5674   "OS Kernel Images" are usually images of some Embedded OS which
5675	will take over control completely. Usually these programs
5676	will install their own set of exception handlers, device
5677	drivers, set up the MMU, etc. - this means, that you cannot
5678	expect to re-enter U-Boot except by resetting the CPU.
5679   "RAMDisk Images" are more or less just data blocks, and their
5680	parameters (address, size) are passed to an OS kernel that is
5681	being started.
5682   "Multi-File Images" contain several images, typically an OS
5683	(Linux) kernel image and one or more data images like
5684	RAMDisks. This construct is useful for instance when you want
5685	to boot over the network using BOOTP etc., where the boot
5686	server provides just a single image file, but you want to get
5687	for instance an OS kernel and a RAMDisk image.
5688
5689	"Multi-File Images" start with a list of image sizes, each
5690	image size (in bytes) specified by an "uint32_t" in network
5691	byte order. This list is terminated by an "(uint32_t)0".
5692	Immediately after the terminating 0 follow the images, one by
5693	one, all aligned on "uint32_t" boundaries (size rounded up to
5694	a multiple of 4 bytes).
5695
5696   "Firmware Images" are binary images containing firmware (like
5697	U-Boot or FPGA images) which usually will be programmed to
5698	flash memory.
5699
5700   "Script files" are command sequences that will be executed by
5701	U-Boot's command interpreter; this feature is especially
5702	useful when you configure U-Boot to use a real shell (hush)
5703	as command interpreter.
5704
5705Booting the Linux zImage:
5706-------------------------
5707
5708On some platforms, it's possible to boot Linux zImage. This is done
5709using the "bootz" command. The syntax of "bootz" command is the same
5710as the syntax of "bootm" command.
5711
5712Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5713kernel with raw initrd images. The syntax is slightly different, the
5714address of the initrd must be augmented by it's size, in the following
5715format: "<initrd addres>:<initrd size>".
5716
5717
5718Standalone HOWTO:
5719=================
5720
5721One of the features of U-Boot is that you can dynamically load and
5722run "standalone" applications, which can use some resources of
5723U-Boot like console I/O functions or interrupt services.
5724
5725Two simple examples are included with the sources:
5726
5727"Hello World" Demo:
5728-------------------
5729
5730'examples/hello_world.c' contains a small "Hello World" Demo
5731application; it is automatically compiled when you build U-Boot.
5732It's configured to run at address 0x00040004, so you can play with it
5733like that:
5734
5735	=> loads
5736	## Ready for S-Record download ...
5737	~>examples/hello_world.srec
5738	1 2 3 4 5 6 7 8 9 10 11 ...
5739	[file transfer complete]
5740	[connected]
5741	## Start Addr = 0x00040004
5742
5743	=> go 40004 Hello World! This is a test.
5744	## Starting application at 0x00040004 ...
5745	Hello World
5746	argc = 7
5747	argv[0] = "40004"
5748	argv[1] = "Hello"
5749	argv[2] = "World!"
5750	argv[3] = "This"
5751	argv[4] = "is"
5752	argv[5] = "a"
5753	argv[6] = "test."
5754	argv[7] = "<NULL>"
5755	Hit any key to exit ...
5756
5757	## Application terminated, rc = 0x0
5758
5759Another example, which demonstrates how to register a CPM interrupt
5760handler with the U-Boot code, can be found in 'examples/timer.c'.
5761Here, a CPM timer is set up to generate an interrupt every second.
5762The interrupt service routine is trivial, just printing a '.'
5763character, but this is just a demo program. The application can be
5764controlled by the following keys:
5765
5766	? - print current values og the CPM Timer registers
5767	b - enable interrupts and start timer
5768	e - stop timer and disable interrupts
5769	q - quit application
5770
5771	=> loads
5772	## Ready for S-Record download ...
5773	~>examples/timer.srec
5774	1 2 3 4 5 6 7 8 9 10 11 ...
5775	[file transfer complete]
5776	[connected]
5777	## Start Addr = 0x00040004
5778
5779	=> go 40004
5780	## Starting application at 0x00040004 ...
5781	TIMERS=0xfff00980
5782	Using timer 1
5783	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5784
5785Hit 'b':
5786	[q, b, e, ?] Set interval 1000000 us
5787	Enabling timer
5788Hit '?':
5789	[q, b, e, ?] ........
5790	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5791Hit '?':
5792	[q, b, e, ?] .
5793	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5794Hit '?':
5795	[q, b, e, ?] .
5796	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
5797Hit '?':
5798	[q, b, e, ?] .
5799	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
5800Hit 'e':
5801	[q, b, e, ?] ...Stopping timer
5802Hit 'q':
5803	[q, b, e, ?] ## Application terminated, rc = 0x0
5804
5805
5806Minicom warning:
5807================
5808
5809Over time, many people have reported problems when trying to use the
5810"minicom" terminal emulation program for serial download. I (wd)
5811consider minicom to be broken, and recommend not to use it. Under
5812Unix, I recommend to use C-Kermit for general purpose use (and
5813especially for kermit binary protocol download ("loadb" command), and
5814use "cu" for S-Record download ("loads" command).  See
5815http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
5816for help with kermit.
5817
5818
5819Nevertheless, if you absolutely want to use it try adding this
5820configuration to your "File transfer protocols" section:
5821
5822	   Name	   Program			Name U/D FullScr IO-Red. Multi
5823	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5824	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5825
5826
5827NetBSD Notes:
5828=============
5829
5830Starting at version 0.9.2, U-Boot supports NetBSD both as host
5831(build U-Boot) and target system (boots NetBSD/mpc8xx).
5832
5833Building requires a cross environment; it is known to work on
5834NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5835need gmake since the Makefiles are not compatible with BSD make).
5836Note that the cross-powerpc package does not install include files;
5837attempting to build U-Boot will fail because <machine/ansi.h> is
5838missing.  This file has to be installed and patched manually:
5839
5840	# cd /usr/pkg/cross/powerpc-netbsd/include
5841	# mkdir powerpc
5842	# ln -s powerpc machine
5843	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5844	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5845
5846Native builds *don't* work due to incompatibilities between native
5847and U-Boot include files.
5848
5849Booting assumes that (the first part of) the image booted is a
5850stage-2 loader which in turn loads and then invokes the kernel
5851proper. Loader sources will eventually appear in the NetBSD source
5852tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5853meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5854
5855
5856Implementation Internals:
5857=========================
5858
5859The following is not intended to be a complete description of every
5860implementation detail. However, it should help to understand the
5861inner workings of U-Boot and make it easier to port it to custom
5862hardware.
5863
5864
5865Initial Stack, Global Data:
5866---------------------------
5867
5868The implementation of U-Boot is complicated by the fact that U-Boot
5869starts running out of ROM (flash memory), usually without access to
5870system RAM (because the memory controller is not initialized yet).
5871This means that we don't have writable Data or BSS segments, and BSS
5872is not initialized as zero. To be able to get a C environment working
5873at all, we have to allocate at least a minimal stack. Implementation
5874options for this are defined and restricted by the CPU used: Some CPU
5875models provide on-chip memory (like the IMMR area on MPC8xx and
5876MPC826x processors), on others (parts of) the data cache can be
5877locked as (mis-) used as memory, etc.
5878
5879	Chris Hallinan posted a good summary of these issues to the
5880	U-Boot mailing list:
5881
5882	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
5883	From: "Chris Hallinan" <clh@net1plus.com>
5884	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
5885	...
5886
5887	Correct me if I'm wrong, folks, but the way I understand it
5888	is this: Using DCACHE as initial RAM for Stack, etc, does not
5889	require any physical RAM backing up the cache. The cleverness
5890	is that the cache is being used as a temporary supply of
5891	necessary storage before the SDRAM controller is setup. It's
5892	beyond the scope of this list to explain the details, but you
5893	can see how this works by studying the cache architecture and
5894	operation in the architecture and processor-specific manuals.
5895
5896	OCM is On Chip Memory, which I believe the 405GP has 4K. It
5897	is another option for the system designer to use as an
5898	initial stack/RAM area prior to SDRAM being available. Either
5899	option should work for you. Using CS 4 should be fine if your
5900	board designers haven't used it for something that would
5901	cause you grief during the initial boot! It is frequently not
5902	used.
5903
5904	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
5905	with your processor/board/system design. The default value
5906	you will find in any recent u-boot distribution in
5907	walnut.h should work for you. I'd set it to a value larger
5908	than your SDRAM module. If you have a 64MB SDRAM module, set
5909	it above 400_0000. Just make sure your board has no resources
5910	that are supposed to respond to that address! That code in
5911	start.S has been around a while and should work as is when
5912	you get the config right.
5913
5914	-Chris Hallinan
5915	DS4.COM, Inc.
5916
5917It is essential to remember this, since it has some impact on the C
5918code for the initialization procedures:
5919
5920* Initialized global data (data segment) is read-only. Do not attempt
5921  to write it.
5922
5923* Do not use any uninitialized global data (or implicitly initialized
5924  as zero data - BSS segment) at all - this is undefined, initiali-
5925  zation is performed later (when relocating to RAM).
5926
5927* Stack space is very limited. Avoid big data buffers or things like
5928  that.
5929
5930Having only the stack as writable memory limits means we cannot use
5931normal global data to share information between the code. But it
5932turned out that the implementation of U-Boot can be greatly
5933simplified by making a global data structure (gd_t) available to all
5934functions. We could pass a pointer to this data as argument to _all_
5935functions, but this would bloat the code. Instead we use a feature of
5936the GCC compiler (Global Register Variables) to share the data: we
5937place a pointer (gd) to the global data into a register which we
5938reserve for this purpose.
5939
5940When choosing a register for such a purpose we are restricted by the
5941relevant  (E)ABI  specifications for the current architecture, and by
5942GCC's implementation.
5943
5944For PowerPC, the following registers have specific use:
5945	R1:	stack pointer
5946	R2:	reserved for system use
5947	R3-R4:	parameter passing and return values
5948	R5-R10: parameter passing
5949	R13:	small data area pointer
5950	R30:	GOT pointer
5951	R31:	frame pointer
5952
5953	(U-Boot also uses R12 as internal GOT pointer. r12
5954	is a volatile register so r12 needs to be reset when
5955	going back and forth between asm and C)
5956
5957    ==> U-Boot will use R2 to hold a pointer to the global data
5958
5959    Note: on PPC, we could use a static initializer (since the
5960    address of the global data structure is known at compile time),
5961    but it turned out that reserving a register results in somewhat
5962    smaller code - although the code savings are not that big (on
5963    average for all boards 752 bytes for the whole U-Boot image,
5964    624 text + 127 data).
5965
5966On Blackfin, the normal C ABI (except for P3) is followed as documented here:
5967	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
5968
5969    ==> U-Boot will use P3 to hold a pointer to the global data
5970
5971On ARM, the following registers are used:
5972
5973	R0:	function argument word/integer result
5974	R1-R3:	function argument word
5975	R9:	platform specific
5976	R10:	stack limit (used only if stack checking is enabled)
5977	R11:	argument (frame) pointer
5978	R12:	temporary workspace
5979	R13:	stack pointer
5980	R14:	link register
5981	R15:	program counter
5982
5983    ==> U-Boot will use R9 to hold a pointer to the global data
5984
5985    Note: on ARM, only R_ARM_RELATIVE relocations are supported.
5986
5987On Nios II, the ABI is documented here:
5988	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
5989
5990    ==> U-Boot will use gp to hold a pointer to the global data
5991
5992    Note: on Nios II, we give "-G0" option to gcc and don't use gp
5993    to access small data sections, so gp is free.
5994
5995On NDS32, the following registers are used:
5996
5997	R0-R1:	argument/return
5998	R2-R5:	argument
5999	R15:	temporary register for assembler
6000	R16:	trampoline register
6001	R28:	frame pointer (FP)
6002	R29:	global pointer (GP)
6003	R30:	link register (LP)
6004	R31:	stack pointer (SP)
6005	PC:	program counter (PC)
6006
6007    ==> U-Boot will use R10 to hold a pointer to the global data
6008
6009NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
6010or current versions of GCC may "optimize" the code too much.
6011
6012Memory Management:
6013------------------
6014
6015U-Boot runs in system state and uses physical addresses, i.e. the
6016MMU is not used either for address mapping nor for memory protection.
6017
6018The available memory is mapped to fixed addresses using the memory
6019controller. In this process, a contiguous block is formed for each
6020memory type (Flash, SDRAM, SRAM), even when it consists of several
6021physical memory banks.
6022
6023U-Boot is installed in the first 128 kB of the first Flash bank (on
6024TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
6025booting and sizing and initializing DRAM, the code relocates itself
6026to the upper end of DRAM. Immediately below the U-Boot code some
6027memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
6028configuration setting]. Below that, a structure with global Board
6029Info data is placed, followed by the stack (growing downward).
6030
6031Additionally, some exception handler code is copied to the low 8 kB
6032of DRAM (0x00000000 ... 0x00001FFF).
6033
6034So a typical memory configuration with 16 MB of DRAM could look like
6035this:
6036
6037	0x0000 0000	Exception Vector code
6038	      :
6039	0x0000 1FFF
6040	0x0000 2000	Free for Application Use
6041	      :
6042	      :
6043
6044	      :
6045	      :
6046	0x00FB FF20	Monitor Stack (Growing downward)
6047	0x00FB FFAC	Board Info Data and permanent copy of global data
6048	0x00FC 0000	Malloc Arena
6049	      :
6050	0x00FD FFFF
6051	0x00FE 0000	RAM Copy of Monitor Code
6052	...		eventually: LCD or video framebuffer
6053	...		eventually: pRAM (Protected RAM - unchanged by reset)
6054	0x00FF FFFF	[End of RAM]
6055
6056
6057System Initialization:
6058----------------------
6059
6060In the reset configuration, U-Boot starts at the reset entry point
6061(on most PowerPC systems at address 0x00000100). Because of the reset
6062configuration for CS0# this is a mirror of the on board Flash memory.
6063To be able to re-map memory U-Boot then jumps to its link address.
6064To be able to implement the initialization code in C, a (small!)
6065initial stack is set up in the internal Dual Ported RAM (in case CPUs
6066which provide such a feature like MPC8xx or MPC8260), or in a locked
6067part of the data cache. After that, U-Boot initializes the CPU core,
6068the caches and the SIU.
6069
6070Next, all (potentially) available memory banks are mapped using a
6071preliminary mapping. For example, we put them on 512 MB boundaries
6072(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
6073on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
6074programmed for SDRAM access. Using the temporary configuration, a
6075simple memory test is run that determines the size of the SDRAM
6076banks.
6077
6078When there is more than one SDRAM bank, and the banks are of
6079different size, the largest is mapped first. For equal size, the first
6080bank (CS2#) is mapped first. The first mapping is always for address
60810x00000000, with any additional banks following immediately to create
6082contiguous memory starting from 0.
6083
6084Then, the monitor installs itself at the upper end of the SDRAM area
6085and allocates memory for use by malloc() and for the global Board
6086Info data; also, the exception vector code is copied to the low RAM
6087pages, and the final stack is set up.
6088
6089Only after this relocation will you have a "normal" C environment;
6090until that you are restricted in several ways, mostly because you are
6091running from ROM, and because the code will have to be relocated to a
6092new address in RAM.
6093
6094
6095U-Boot Porting Guide:
6096----------------------
6097
6098[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
6099list, October 2002]
6100
6101
6102int main(int argc, char *argv[])
6103{
6104	sighandler_t no_more_time;
6105
6106	signal(SIGALRM, no_more_time);
6107	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
6108
6109	if (available_money > available_manpower) {
6110		Pay consultant to port U-Boot;
6111		return 0;
6112	}
6113
6114	Download latest U-Boot source;
6115
6116	Subscribe to u-boot mailing list;
6117
6118	if (clueless)
6119		email("Hi, I am new to U-Boot, how do I get started?");
6120
6121	while (learning) {
6122		Read the README file in the top level directory;
6123		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
6124		Read applicable doc/*.README;
6125		Read the source, Luke;
6126		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
6127	}
6128
6129	if (available_money > toLocalCurrency ($2500))
6130		Buy a BDI3000;
6131	else
6132		Add a lot of aggravation and time;
6133
6134	if (a similar board exists) {	/* hopefully... */
6135		cp -a board/<similar> board/<myboard>
6136		cp include/configs/<similar>.h include/configs/<myboard>.h
6137	} else {
6138		Create your own board support subdirectory;
6139		Create your own board include/configs/<myboard>.h file;
6140	}
6141	Edit new board/<myboard> files
6142	Edit new include/configs/<myboard>.h
6143
6144	while (!accepted) {
6145		while (!running) {
6146			do {
6147				Add / modify source code;
6148			} until (compiles);
6149			Debug;
6150			if (clueless)
6151				email("Hi, I am having problems...");
6152		}
6153		Send patch file to the U-Boot email list;
6154		if (reasonable critiques)
6155			Incorporate improvements from email list code review;
6156		else
6157			Defend code as written;
6158	}
6159
6160	return 0;
6161}
6162
6163void no_more_time (int sig)
6164{
6165      hire_a_guru();
6166}
6167
6168
6169Coding Standards:
6170-----------------
6171
6172All contributions to U-Boot should conform to the Linux kernel
6173coding style; see the file "Documentation/CodingStyle" and the script
6174"scripts/Lindent" in your Linux kernel source directory.
6175
6176Source files originating from a different project (for example the
6177MTD subsystem) are generally exempt from these guidelines and are not
6178reformatted to ease subsequent migration to newer versions of those
6179sources.
6180
6181Please note that U-Boot is implemented in C (and to some small parts in
6182Assembler); no C++ is used, so please do not use C++ style comments (//)
6183in your code.
6184
6185Please also stick to the following formatting rules:
6186- remove any trailing white space
6187- use TAB characters for indentation and vertical alignment, not spaces
6188- make sure NOT to use DOS '\r\n' line feeds
6189- do not add more than 2 consecutive empty lines to source files
6190- do not add trailing empty lines to source files
6191
6192Submissions which do not conform to the standards may be returned
6193with a request to reformat the changes.
6194
6195
6196Submitting Patches:
6197-------------------
6198
6199Since the number of patches for U-Boot is growing, we need to
6200establish some rules. Submissions which do not conform to these rules
6201may be rejected, even when they contain important and valuable stuff.
6202
6203Please see http://www.denx.de/wiki/U-Boot/Patches for details.
6204
6205Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
6206see http://lists.denx.de/mailman/listinfo/u-boot
6207
6208When you send a patch, please include the following information with
6209it:
6210
6211* For bug fixes: a description of the bug and how your patch fixes
6212  this bug. Please try to include a way of demonstrating that the
6213  patch actually fixes something.
6214
6215* For new features: a description of the feature and your
6216  implementation.
6217
6218* A CHANGELOG entry as plaintext (separate from the patch)
6219
6220* For major contributions, add a MAINTAINERS file with your
6221  information and associated file and directory references.
6222
6223* When you add support for a new board, don't forget to add a
6224  maintainer e-mail address to the boards.cfg file, too.
6225
6226* If your patch adds new configuration options, don't forget to
6227  document these in the README file.
6228
6229* The patch itself. If you are using git (which is *strongly*
6230  recommended) you can easily generate the patch using the
6231  "git format-patch". If you then use "git send-email" to send it to
6232  the U-Boot mailing list, you will avoid most of the common problems
6233  with some other mail clients.
6234
6235  If you cannot use git, use "diff -purN OLD NEW". If your version of
6236  diff does not support these options, then get the latest version of
6237  GNU diff.
6238
6239  The current directory when running this command shall be the parent
6240  directory of the U-Boot source tree (i. e. please make sure that
6241  your patch includes sufficient directory information for the
6242  affected files).
6243
6244  We prefer patches as plain text. MIME attachments are discouraged,
6245  and compressed attachments must not be used.
6246
6247* If one logical set of modifications affects or creates several
6248  files, all these changes shall be submitted in a SINGLE patch file.
6249
6250* Changesets that contain different, unrelated modifications shall be
6251  submitted as SEPARATE patches, one patch per changeset.
6252
6253
6254Notes:
6255
6256* Before sending the patch, run the buildman script on your patched
6257  source tree and make sure that no errors or warnings are reported
6258  for any of the boards.
6259
6260* Keep your modifications to the necessary minimum: A patch
6261  containing several unrelated changes or arbitrary reformats will be
6262  returned with a request to re-formatting / split it.
6263
6264* If you modify existing code, make sure that your new code does not
6265  add to the memory footprint of the code ;-) Small is beautiful!
6266  When adding new features, these should compile conditionally only
6267  (using #ifdef), and the resulting code with the new feature
6268  disabled must not need more memory than the old code without your
6269  modification.
6270
6271* Remember that there is a size limit of 100 kB per message on the
6272  u-boot mailing list. Bigger patches will be moderated. If they are
6273  reasonable and not too big, they will be acknowledged. But patches
6274  bigger than the size limit should be avoided.
6275