xref: /openbmc/u-boot/README (revision 8dd026bf)
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  /m68k			Files generic to m68k architecture
141  /microblaze		Files generic to microblaze architecture
142  /mips			Files generic to MIPS architecture
143  /nds32		Files generic to NDS32 architecture
144  /nios2		Files generic to Altera NIOS2 architecture
145  /openrisc		Files generic to OpenRISC architecture
146  /powerpc		Files generic to PowerPC architecture
147  /sandbox		Files generic to HW-independent "sandbox"
148  /sh			Files generic to SH architecture
149  /x86			Files generic to x86 architecture
150/api			Machine/arch independent API for external apps
151/board			Board dependent files
152/cmd			U-Boot commands functions
153/common			Misc architecture independent functions
154/configs		Board default configuration files
155/disk			Code for disk drive partition handling
156/doc			Documentation (don't expect too much)
157/drivers		Commonly used device drivers
158/dts			Contains Makefile for building internal U-Boot fdt.
159/examples		Example code for standalone applications, etc.
160/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
161/include		Header Files
162/lib			Library routines generic to all architectures
163/Licenses		Various license files
164/net			Networking code
165/post			Power On Self Test
166/scripts		Various build scripts and Makefiles
167/test			Various unit test files
168/tools			Tools to build S-Record or U-Boot images, etc.
169
170Software Configuration:
171=======================
172
173Configuration is usually done using C preprocessor defines; the
174rationale behind that is to avoid dead code whenever possible.
175
176There are two classes of configuration variables:
177
178* Configuration _OPTIONS_:
179  These are selectable by the user and have names beginning with
180  "CONFIG_".
181
182* Configuration _SETTINGS_:
183  These depend on the hardware etc. and should not be meddled with if
184  you don't know what you're doing; they have names beginning with
185  "CONFIG_SYS_".
186
187Previously, all configuration was done by hand, which involved creating
188symbolic links and editing configuration files manually. More recently,
189U-Boot has added the Kbuild infrastructure used by the Linux kernel,
190allowing you to use the "make menuconfig" command to configure your
191build.
192
193
194Selection of Processor Architecture and Board Type:
195---------------------------------------------------
196
197For all supported boards there are ready-to-use default
198configurations available; just type "make <board_name>_defconfig".
199
200Example: For a TQM823L module type:
201
202	cd u-boot
203	make TQM823L_defconfig
204
205Note: If you're looking for the default configuration file for a board
206you're sure used to be there but is now missing, check the file
207doc/README.scrapyard for a list of no longer supported boards.
208
209Sandbox Environment:
210--------------------
211
212U-Boot can be built natively to run on a Linux host using the 'sandbox'
213board. This allows feature development which is not board- or architecture-
214specific to be undertaken on a native platform. The sandbox is also used to
215run some of U-Boot's tests.
216
217See board/sandbox/README.sandbox for more details.
218
219
220Board Initialisation Flow:
221--------------------------
222
223This is the intended start-up flow for boards. This should apply for both
224SPL and U-Boot proper (i.e. they both follow the same rules).
225
226Note: "SPL" stands for "Secondary Program Loader," which is explained in
227more detail later in this file.
228
229At present, SPL mostly uses a separate code path, but the function names
230and roles of each function are the same. Some boards or architectures
231may not conform to this.  At least most ARM boards which use
232CONFIG_SPL_FRAMEWORK conform to this.
233
234Execution typically starts with an architecture-specific (and possibly
235CPU-specific) start.S file, such as:
236
237	- arch/arm/cpu/armv7/start.S
238	- arch/powerpc/cpu/mpc83xx/start.S
239	- arch/mips/cpu/start.S
240
241and so on. From there, three functions are called; the purpose and
242limitations of each of these functions are described below.
243
244lowlevel_init():
245	- purpose: essential init to permit execution to reach board_init_f()
246	- no global_data or BSS
247	- there is no stack (ARMv7 may have one but it will soon be removed)
248	- must not set up SDRAM or use console
249	- must only do the bare minimum to allow execution to continue to
250		board_init_f()
251	- this is almost never needed
252	- return normally from this function
253
254board_init_f():
255	- purpose: set up the machine ready for running board_init_r():
256		i.e. SDRAM and serial UART
257	- global_data is available
258	- stack is in SRAM
259	- BSS is not available, so you cannot use global/static variables,
260		only stack variables and global_data
261
262	Non-SPL-specific notes:
263	- dram_init() is called to set up DRAM. If already done in SPL this
264		can do nothing
265
266	SPL-specific notes:
267	- you can override the entire board_init_f() function with your own
268		version as needed.
269	- preloader_console_init() can be called here in extremis
270	- should set up SDRAM, and anything needed to make the UART work
271	- these is no need to clear BSS, it will be done by crt0.S
272	- must return normally from this function (don't call board_init_r()
273		directly)
274
275Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
276this point the stack and global_data are relocated to below
277CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
278memory.
279
280board_init_r():
281	- purpose: main execution, common code
282	- global_data is available
283	- SDRAM is available
284	- BSS is available, all static/global variables can be used
285	- execution eventually continues to main_loop()
286
287	Non-SPL-specific notes:
288	- U-Boot is relocated to the top of memory and is now running from
289		there.
290
291	SPL-specific notes:
292	- stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
293		CONFIG_SPL_STACK_R_ADDR points into SDRAM
294	- preloader_console_init() can be called here - typically this is
295		done by selecting CONFIG_SPL_BOARD_INIT and then supplying a
296		spl_board_init() function containing this call
297	- loads U-Boot or (in falcon mode) Linux
298
299
300
301Configuration Options:
302----------------------
303
304Configuration depends on the combination of board and CPU type; all
305such information is kept in a configuration file
306"include/configs/<board_name>.h".
307
308Example: For a TQM823L module, all configuration settings are in
309"include/configs/TQM823L.h".
310
311
312Many of the options are named exactly as the corresponding Linux
313kernel configuration options. The intention is to make it easier to
314build a config tool - later.
315
316
317The following options need to be configured:
318
319- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
320
321- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
322
323- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
324		Define exactly one, e.g. CONFIG_ATSTK1002
325
326- Marvell Family Member
327		CONFIG_SYS_MVFS		- define it if you want to enable
328					  multiple fs option at one time
329					  for marvell soc family
330
331- 8xx CPU Options: (if using an MPC8xx CPU)
332		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
333					  get_gclk_freq() cannot work
334					  e.g. if there is no 32KHz
335					  reference PIT/RTC clock
336		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
337					  or XTAL/EXTAL)
338
339- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
340		CONFIG_SYS_8xx_CPUCLK_MIN
341		CONFIG_SYS_8xx_CPUCLK_MAX
342		CONFIG_8xx_CPUCLK_DEFAULT
343			See doc/README.MPC866
344
345		CONFIG_SYS_MEASURE_CPUCLK
346
347		Define this to measure the actual CPU clock instead
348		of relying on the correctness of the configured
349		values. Mostly useful for board bringup to make sure
350		the PLL is locked at the intended frequency. Note
351		that this requires a (stable) reference clock (32 kHz
352		RTC clock or CONFIG_SYS_8XX_XIN)
353
354		CONFIG_SYS_DELAYED_ICACHE
355
356		Define this option if you want to enable the
357		ICache only when Code runs from RAM.
358
359- 85xx CPU Options:
360		CONFIG_SYS_PPC64
361
362		Specifies that the core is a 64-bit PowerPC implementation (implements
363		the "64" category of the Power ISA). This is necessary for ePAPR
364		compliance, among other possible reasons.
365
366		CONFIG_SYS_FSL_TBCLK_DIV
367
368		Defines the core time base clock divider ratio compared to the
369		system clock.  On most PQ3 devices this is 8, on newer QorIQ
370		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
371
372		CONFIG_SYS_FSL_PCIE_COMPAT
373
374		Defines the string to utilize when trying to match PCIe device
375		tree nodes for the given platform.
376
377		CONFIG_SYS_FSL_ERRATUM_A004510
378
379		Enables a workaround for erratum A004510.  If set,
380		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
381		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
382
383		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
384		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
385
386		Defines one or two SoC revisions (low 8 bits of SVR)
387		for which the A004510 workaround should be applied.
388
389		The rest of SVR is either not relevant to the decision
390		of whether the erratum is present (e.g. p2040 versus
391		p2041) or is implied by the build target, which controls
392		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
393
394		See Freescale App Note 4493 for more information about
395		this erratum.
396
397		CONFIG_A003399_NOR_WORKAROUND
398		Enables a workaround for IFC erratum A003399. It is only
399		required during NOR boot.
400
401		CONFIG_A008044_WORKAROUND
402		Enables a workaround for T1040/T1042 erratum A008044. It is only
403		required during NAND boot and valid for Rev 1.0 SoC revision
404
405		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
406
407		This is the value to write into CCSR offset 0x18600
408		according to the A004510 workaround.
409
410		CONFIG_SYS_FSL_DSP_DDR_ADDR
411		This value denotes start offset of DDR memory which is
412		connected exclusively to the DSP cores.
413
414		CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
415		This value denotes start offset of M2 memory
416		which is directly connected to the DSP core.
417
418		CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
419		This value denotes start offset of M3 memory which is directly
420		connected to the DSP core.
421
422		CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
423		This value denotes start offset of DSP CCSR space.
424
425		CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
426		Single Source Clock is clocking mode present in some of FSL SoC's.
427		In this mode, a single differential clock is used to supply
428		clocks to the sysclock, ddrclock and usbclock.
429
430		CONFIG_SYS_CPC_REINIT_F
431		This CONFIG is defined when the CPC is configured as SRAM at the
432		time of U-Boot entry and is required to be re-initialized.
433
434		CONFIG_DEEP_SLEEP
435		Indicates this SoC supports deep sleep feature. If deep sleep is
436		supported, core will start to execute uboot when wakes up.
437
438- Generic CPU options:
439		CONFIG_SYS_GENERIC_GLOBAL_DATA
440		Defines global data is initialized in generic board board_init_f().
441		If this macro is defined, global data is created and cleared in
442		generic board board_init_f(). Without this macro, architecture/board
443		should initialize global data before calling board_init_f().
444
445		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
446
447		Defines the endianess of the CPU. Implementation of those
448		values is arch specific.
449
450		CONFIG_SYS_FSL_DDR
451		Freescale DDR driver in use. This type of DDR controller is
452		found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
453		SoCs.
454
455		CONFIG_SYS_FSL_DDR_ADDR
456		Freescale DDR memory-mapped register base.
457
458		CONFIG_SYS_FSL_DDR_EMU
459		Specify emulator support for DDR. Some DDR features such as
460		deskew training are not available.
461
462		CONFIG_SYS_FSL_DDRC_GEN1
463		Freescale DDR1 controller.
464
465		CONFIG_SYS_FSL_DDRC_GEN2
466		Freescale DDR2 controller.
467
468		CONFIG_SYS_FSL_DDRC_GEN3
469		Freescale DDR3 controller.
470
471		CONFIG_SYS_FSL_DDRC_GEN4
472		Freescale DDR4 controller.
473
474		CONFIG_SYS_FSL_DDRC_ARM_GEN3
475		Freescale DDR3 controller for ARM-based SoCs.
476
477		CONFIG_SYS_FSL_DDR1
478		Board config to use DDR1. It can be enabled for SoCs with
479		Freescale DDR1 or DDR2 controllers, depending on the board
480		implemetation.
481
482		CONFIG_SYS_FSL_DDR2
483		Board config to use DDR2. It can be enabled for SoCs with
484		Freescale DDR2 or DDR3 controllers, depending on the board
485		implementation.
486
487		CONFIG_SYS_FSL_DDR3
488		Board config to use DDR3. It can be enabled for SoCs with
489		Freescale DDR3 or DDR3L controllers.
490
491		CONFIG_SYS_FSL_DDR3L
492		Board config to use DDR3L. It can be enabled for SoCs with
493		DDR3L controllers.
494
495		CONFIG_SYS_FSL_DDR4
496		Board config to use DDR4. It can be enabled for SoCs with
497		DDR4 controllers.
498
499		CONFIG_SYS_FSL_IFC_BE
500		Defines the IFC controller register space as Big Endian
501
502		CONFIG_SYS_FSL_IFC_LE
503		Defines the IFC controller register space as Little Endian
504
505		CONFIG_SYS_FSL_IFC_CLK_DIV
506		Defines divider of platform clock(clock input to IFC controller).
507
508		CONFIG_SYS_FSL_LBC_CLK_DIV
509		Defines divider of platform clock(clock input to eLBC controller).
510
511		CONFIG_SYS_FSL_PBL_PBI
512		It enables addition of RCW (Power on reset configuration) in built image.
513		Please refer doc/README.pblimage for more details
514
515		CONFIG_SYS_FSL_PBL_RCW
516		It adds PBI(pre-boot instructions) commands in u-boot build image.
517		PBI commands can be used to configure SoC before it starts the execution.
518		Please refer doc/README.pblimage for more details
519
520		CONFIG_SPL_FSL_PBL
521		It adds a target to create boot binary having SPL binary in PBI format
522		concatenated with u-boot binary.
523
524		CONFIG_SYS_FSL_DDR_BE
525		Defines the DDR controller register space as Big Endian
526
527		CONFIG_SYS_FSL_DDR_LE
528		Defines the DDR controller register space as Little Endian
529
530		CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
531		Physical address from the view of DDR controllers. It is the
532		same as CONFIG_SYS_DDR_SDRAM_BASE for  all Power SoCs. But
533		it could be different for ARM SoCs.
534
535		CONFIG_SYS_FSL_DDR_INTLV_256B
536		DDR controller interleaving on 256-byte. This is a special
537		interleaving mode, handled by Dickens for Freescale layerscape
538		SoCs with ARM core.
539
540		CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
541		Number of controllers used as main memory.
542
543		CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
544		Number of controllers used for other than main memory.
545
546		CONFIG_SYS_FSL_HAS_DP_DDR
547		Defines the SoC has DP-DDR used for DPAA.
548
549		CONFIG_SYS_FSL_SEC_BE
550		Defines the SEC controller register space as Big Endian
551
552		CONFIG_SYS_FSL_SEC_LE
553		Defines the SEC controller register space as Little Endian
554
555- MIPS CPU options:
556		CONFIG_SYS_INIT_SP_OFFSET
557
558		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
559		pointer. This is needed for the temporary stack before
560		relocation.
561
562		CONFIG_SYS_MIPS_CACHE_MODE
563
564		Cache operation mode for the MIPS CPU.
565		See also arch/mips/include/asm/mipsregs.h.
566		Possible values are:
567			CONF_CM_CACHABLE_NO_WA
568			CONF_CM_CACHABLE_WA
569			CONF_CM_UNCACHED
570			CONF_CM_CACHABLE_NONCOHERENT
571			CONF_CM_CACHABLE_CE
572			CONF_CM_CACHABLE_COW
573			CONF_CM_CACHABLE_CUW
574			CONF_CM_CACHABLE_ACCELERATED
575
576		CONFIG_SYS_XWAY_EBU_BOOTCFG
577
578		Special option for Lantiq XWAY SoCs for booting from NOR flash.
579		See also arch/mips/cpu/mips32/start.S.
580
581		CONFIG_XWAY_SWAP_BYTES
582
583		Enable compilation of tools/xway-swap-bytes needed for Lantiq
584		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
585		be swapped if a flash programmer is used.
586
587- ARM options:
588		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
589
590		Select high exception vectors of the ARM core, e.g., do not
591		clear the V bit of the c1 register of CP15.
592
593		COUNTER_FREQUENCY
594		Generic timer clock source frequency.
595
596		COUNTER_FREQUENCY_REAL
597		Generic timer clock source frequency if the real clock is
598		different from COUNTER_FREQUENCY, and can only be determined
599		at run time.
600
601- Tegra SoC options:
602		CONFIG_TEGRA_SUPPORT_NON_SECURE
603
604		Support executing U-Boot in non-secure (NS) mode. Certain
605		impossible actions will be skipped if the CPU is in NS mode,
606		such as ARM architectural timer initialization.
607
608- Linux Kernel Interface:
609		CONFIG_CLOCKS_IN_MHZ
610
611		U-Boot stores all clock information in Hz
612		internally. For binary compatibility with older Linux
613		kernels (which expect the clocks passed in the
614		bd_info data to be in MHz) the environment variable
615		"clocks_in_mhz" can be defined so that U-Boot
616		converts clock data to MHZ before passing it to the
617		Linux kernel.
618		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
619		"clocks_in_mhz=1" is automatically included in the
620		default environment.
621
622		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
623
624		When transferring memsize parameter to Linux, some versions
625		expect it to be in bytes, others in MB.
626		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
627
628		CONFIG_OF_LIBFDT
629
630		New kernel versions are expecting firmware settings to be
631		passed using flattened device trees (based on open firmware
632		concepts).
633
634		CONFIG_OF_LIBFDT
635		 * New libfdt-based support
636		 * Adds the "fdt" command
637		 * The bootm command automatically updates the fdt
638
639		OF_CPU - The proper name of the cpus node (only required for
640			MPC512X and MPC5xxx based boards).
641		OF_SOC - The proper name of the soc node (only required for
642			MPC512X and MPC5xxx based boards).
643		OF_TBCLK - The timebase frequency.
644		OF_STDOUT_PATH - The path to the console device
645
646		boards with QUICC Engines require OF_QE to set UCC MAC
647		addresses
648
649		CONFIG_OF_BOARD_SETUP
650
651		Board code has addition modification that it wants to make
652		to the flat device tree before handing it off to the kernel
653
654		CONFIG_OF_SYSTEM_SETUP
655
656		Other code has addition modification that it wants to make
657		to the flat device tree before handing it off to the kernel.
658		This causes ft_system_setup() to be called before booting
659		the kernel.
660
661		CONFIG_OF_IDE_FIXUP
662
663		U-Boot can detect if an IDE device is present or not.
664		If not, and this new config option is activated, U-Boot
665		removes the ATA node from the DTS before booting Linux,
666		so the Linux IDE driver does not probe the device and
667		crash. This is needed for buggy hardware (uc101) where
668		no pull down resistor is connected to the signal IDE5V_DD7.
669
670		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
671
672		This setting is mandatory for all boards that have only one
673		machine type and must be used to specify the machine type
674		number as it appears in the ARM machine registry
675		(see http://www.arm.linux.org.uk/developer/machines/).
676		Only boards that have multiple machine types supported
677		in a single configuration file and the machine type is
678		runtime discoverable, do not have to use this setting.
679
680- vxWorks boot parameters:
681
682		bootvx constructs a valid bootline using the following
683		environments variables: bootdev, bootfile, ipaddr, netmask,
684		serverip, gatewayip, hostname, othbootargs.
685		It loads the vxWorks image pointed bootfile.
686
687		Note: If a "bootargs" environment is defined, it will overwride
688		the defaults discussed just above.
689
690- Cache Configuration:
691		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
692		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
693		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
694
695- Cache Configuration for ARM:
696		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
697				      controller
698		CONFIG_SYS_PL310_BASE - Physical base address of PL310
699					controller register space
700
701- Serial Ports:
702		CONFIG_PL010_SERIAL
703
704		Define this if you want support for Amba PrimeCell PL010 UARTs.
705
706		CONFIG_PL011_SERIAL
707
708		Define this if you want support for Amba PrimeCell PL011 UARTs.
709
710		CONFIG_PL011_CLOCK
711
712		If you have Amba PrimeCell PL011 UARTs, set this variable to
713		the clock speed of the UARTs.
714
715		CONFIG_PL01x_PORTS
716
717		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
718		define this to a list of base addresses for each (supported)
719		port. See e.g. include/configs/versatile.h
720
721		CONFIG_SERIAL_HW_FLOW_CONTROL
722
723		Define this variable to enable hw flow control in serial driver.
724		Current user of this option is drivers/serial/nsl16550.c driver
725
726- Console Interface:
727		Depending on board, define exactly one serial port
728		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
729		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
730		console by defining CONFIG_8xx_CONS_NONE
731
732		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
733		port routines must be defined elsewhere
734		(i.e. serial_init(), serial_getc(), ...)
735
736- Console Baudrate:
737		CONFIG_BAUDRATE - in bps
738		Select one of the baudrates listed in
739		CONFIG_SYS_BAUDRATE_TABLE, see below.
740		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
741
742- Console Rx buffer length
743		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
744		the maximum receive buffer length for the SMC.
745		This option is actual only for 82xx and 8xx possible.
746		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
747		must be defined, to setup the maximum idle timeout for
748		the SMC.
749
750- Autoboot Command:
751		CONFIG_BOOTCOMMAND
752		Only needed when CONFIG_BOOTDELAY is enabled;
753		define a command string that is automatically executed
754		when no character is read on the console interface
755		within "Boot Delay" after reset.
756
757		CONFIG_BOOTARGS
758		This can be used to pass arguments to the bootm
759		command. The value of CONFIG_BOOTARGS goes into the
760		environment value "bootargs".
761
762		CONFIG_RAMBOOT and CONFIG_NFSBOOT
763		The value of these goes into the environment as
764		"ramboot" and "nfsboot" respectively, and can be used
765		as a convenience, when switching between booting from
766		RAM and NFS.
767
768- Bootcount:
769		CONFIG_BOOTCOUNT_LIMIT
770		Implements a mechanism for detecting a repeating reboot
771		cycle, see:
772		http://www.denx.de/wiki/view/DULG/UBootBootCountLimit
773
774		CONFIG_BOOTCOUNT_ENV
775		If no softreset save registers are found on the hardware
776		"bootcount" is stored in the environment. To prevent a
777		saveenv on all reboots, the environment variable
778		"upgrade_available" is used. If "upgrade_available" is
779		0, "bootcount" is always 0, if "upgrade_available" is
780		1 "bootcount" is incremented in the environment.
781		So the Userspace Applikation must set the "upgrade_available"
782		and "bootcount" variable to 0, if a boot was successfully.
783
784- Pre-Boot Commands:
785		CONFIG_PREBOOT
786
787		When this option is #defined, the existence of the
788		environment variable "preboot" will be checked
789		immediately before starting the CONFIG_BOOTDELAY
790		countdown and/or running the auto-boot command resp.
791		entering interactive mode.
792
793		This feature is especially useful when "preboot" is
794		automatically generated or modified. For an example
795		see the LWMON board specific code: here "preboot" is
796		modified when the user holds down a certain
797		combination of keys on the (special) keyboard when
798		booting the systems
799
800- Serial Download Echo Mode:
801		CONFIG_LOADS_ECHO
802		If defined to 1, all characters received during a
803		serial download (using the "loads" command) are
804		echoed back. This might be needed by some terminal
805		emulations (like "cu"), but may as well just take
806		time on others. This setting #define's the initial
807		value of the "loads_echo" environment variable.
808
809- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
810		CONFIG_KGDB_BAUDRATE
811		Select one of the baudrates listed in
812		CONFIG_SYS_BAUDRATE_TABLE, see below.
813
814- Monitor Functions:
815		Monitor commands can be included or excluded
816		from the build by using the #include files
817		<config_cmd_all.h> and #undef'ing unwanted
818		commands, or adding #define's for wanted commands.
819
820		The default command configuration includes all commands
821		except those marked below with a "*".
822
823		CONFIG_CMD_AES		  AES 128 CBC encrypt/decrypt
824		CONFIG_CMD_ASKENV	* ask for env variable
825		CONFIG_CMD_BDI		  bdinfo
826		CONFIG_CMD_BOOTD	  bootd
827		CONFIG_CMD_BOOTI	* ARM64 Linux kernel Image support
828		CONFIG_CMD_CACHE	* icache, dcache
829		CONFIG_CMD_CONSOLE	  coninfo
830		CONFIG_CMD_CRC32	* crc32
831		CONFIG_CMD_DHCP		* DHCP support
832		CONFIG_CMD_DIAG		* Diagnostics
833		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
834		CONFIG_CMD_DTT		* Digital Therm and Thermostat
835		CONFIG_CMD_ECHO		  echo arguments
836		CONFIG_CMD_EDITENV	  edit env variable
837		CONFIG_CMD_EEPROM	* EEPROM read/write support
838		CONFIG_CMD_EEPROM_LAYOUT* EEPROM layout aware commands
839		CONFIG_CMD_ELF		* bootelf, bootvx
840		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
841		CONFIG_CMD_ENV_FLAGS	* display details about env flags
842		CONFIG_CMD_ENV_EXISTS	* check existence of env variable
843		CONFIG_CMD_EXPORTENV	* export the environment
844		CONFIG_CMD_EXT2		* ext2 command support
845		CONFIG_CMD_EXT4		* ext4 command support
846		CONFIG_CMD_FS_GENERIC	* filesystem commands (e.g. load, ls)
847					  that work for multiple fs types
848		CONFIG_CMD_FS_UUID	* Look up a filesystem UUID
849		CONFIG_CMD_SAVEENV	  saveenv
850		CONFIG_CMD_FDC		* Floppy Disk Support
851		CONFIG_CMD_FAT		* FAT command support
852		CONFIG_CMD_FLASH	  flinfo, erase, protect
853		CONFIG_CMD_FPGA		  FPGA device initialization support
854		CONFIG_CMD_FUSE		* Device fuse support
855		CONFIG_CMD_GETTIME	* Get time since boot
856		CONFIG_CMD_GO		* the 'go' command (exec code)
857		CONFIG_CMD_GREPENV	* search environment
858		CONFIG_CMD_HASH		* calculate hash / digest
859		CONFIG_CMD_I2C		* I2C serial bus support
860		CONFIG_CMD_IDE		* IDE harddisk support
861		CONFIG_CMD_IMI		  iminfo
862		CONFIG_CMD_IMLS		  List all images found in NOR flash
863		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash
864		CONFIG_CMD_IMMAP	* IMMR dump support
865		CONFIG_CMD_IOTRACE	* I/O tracing for debugging
866		CONFIG_CMD_IMPORTENV	* import an environment
867		CONFIG_CMD_INI		* import data from an ini file into the env
868		CONFIG_CMD_IRQ		* irqinfo
869		CONFIG_CMD_ITEST	  Integer/string test of 2 values
870		CONFIG_CMD_JFFS2	* JFFS2 Support
871		CONFIG_CMD_KGDB		* kgdb
872		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)
873		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
874					  (169.254.*.*)
875		CONFIG_CMD_LOADB	  loadb
876		CONFIG_CMD_LOADS	  loads
877		CONFIG_CMD_MD5SUM	* print md5 message digest
878					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
879		CONFIG_CMD_MEMINFO	* Display detailed memory information
880		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
881					  loop, loopw
882		CONFIG_CMD_MEMTEST	* mtest
883		CONFIG_CMD_MISC		  Misc functions like sleep etc
884		CONFIG_CMD_MMC		* MMC memory mapped support
885		CONFIG_CMD_MII		* MII utility commands
886		CONFIG_CMD_MTDPARTS	* MTD partition support
887		CONFIG_CMD_NAND		* NAND support
888		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
889		CONFIG_CMD_NFS		  NFS support
890		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
891		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
892		CONFIG_CMD_PCI		* pciinfo
893		CONFIG_CMD_PCMCIA		* PCMCIA support
894		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
895					  host
896		CONFIG_CMD_PORTIO	* Port I/O
897		CONFIG_CMD_READ		* Read raw data from partition
898		CONFIG_CMD_REGINFO	* Register dump
899		CONFIG_CMD_RUN		  run command in env variable
900		CONFIG_CMD_SANDBOX	* sb command to access sandbox features
901		CONFIG_CMD_SAVES	* save S record dump
902		CONFIG_SCSI		* SCSI Support
903		CONFIG_CMD_SDRAM	* print SDRAM configuration information
904					  (requires CONFIG_CMD_I2C)
905		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
906					  (4xx only)
907		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
908		CONFIG_CMD_SHA1SUM	* print sha1 memory digest
909					  (requires CONFIG_CMD_MEMORY)
910		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x
911		CONFIG_CMD_SOURCE	  "source" command Support
912		CONFIG_CMD_SPI		* SPI serial bus support
913		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
914		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
915		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
916		CONFIG_CMD_TIMER	* access to the system tick timer
917		CONFIG_CMD_USB		* USB support
918		CONFIG_CMD_CDP		* Cisco Discover Protocol support
919		CONFIG_CMD_MFSL		* Microblaze FSL support
920		CONFIG_CMD_XIMG		  Load part of Multi Image
921		CONFIG_CMD_UUID		* Generate random UUID or GUID string
922
923		EXAMPLE: If you want all functions except of network
924		support you can write:
925
926		#include "config_cmd_all.h"
927		#undef CONFIG_CMD_NET
928
929	Other Commands:
930		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
931
932	Note:	Don't enable the "icache" and "dcache" commands
933		(configuration option CONFIG_CMD_CACHE) unless you know
934		what you (and your U-Boot users) are doing. Data
935		cache cannot be enabled on systems like the 8xx or
936		8260 (where accesses to the IMMR region must be
937		uncached), and it cannot be disabled on all other
938		systems where we (mis-) use the data cache to hold an
939		initial stack and some data.
940
941
942		XXX - this list needs to get updated!
943
944- Removal of commands
945		If no commands are needed to boot, you can disable
946		CONFIG_CMDLINE to remove them. In this case, the command line
947		will not be available, and when U-Boot wants to execute the
948		boot command (on start-up) it will call board_run_command()
949		instead. This can reduce image size significantly for very
950		simple boot procedures.
951
952- Regular expression support:
953		CONFIG_REGEX
954		If this variable is defined, U-Boot is linked against
955		the SLRE (Super Light Regular Expression) library,
956		which adds regex support to some commands, as for
957		example "env grep" and "setexpr".
958
959- Device tree:
960		CONFIG_OF_CONTROL
961		If this variable is defined, U-Boot will use a device tree
962		to configure its devices, instead of relying on statically
963		compiled #defines in the board file. This option is
964		experimental and only available on a few boards. The device
965		tree is available in the global data as gd->fdt_blob.
966
967		U-Boot needs to get its device tree from somewhere. This can
968		be done using one of the three options below:
969
970		CONFIG_OF_EMBED
971		If this variable is defined, U-Boot will embed a device tree
972		binary in its image. This device tree file should be in the
973		board directory and called <soc>-<board>.dts. The binary file
974		is then picked up in board_init_f() and made available through
975		the global data structure as gd->blob.
976
977		CONFIG_OF_SEPARATE
978		If this variable is defined, U-Boot will build a device tree
979		binary. It will be called u-boot.dtb. Architecture-specific
980		code will locate it at run-time. Generally this works by:
981
982			cat u-boot.bin u-boot.dtb >image.bin
983
984		and in fact, U-Boot does this for you, creating a file called
985		u-boot-dtb.bin which is useful in the common case. You can
986		still use the individual files if you need something more
987		exotic.
988
989		CONFIG_OF_BOARD
990		If this variable is defined, U-Boot will use the device tree
991		provided by the board at runtime instead of embedding one with
992		the image. Only boards defining board_fdt_blob_setup() support
993		this option (see include/fdtdec.h file).
994
995- Watchdog:
996		CONFIG_WATCHDOG
997		If this variable is defined, it enables watchdog
998		support for the SoC. There must be support in the SoC
999		specific code for a watchdog. For the 8xx and 8260
1000		CPUs, the SIU Watchdog feature is enabled in the SYPCR
1001		register.  When supported for a specific SoC is
1002		available, then no further board specific code should
1003		be needed to use it.
1004
1005		CONFIG_HW_WATCHDOG
1006		When using a watchdog circuitry external to the used
1007		SoC, then define this variable and provide board
1008		specific code for the "hw_watchdog_reset" function.
1009
1010		CONFIG_AT91_HW_WDT_TIMEOUT
1011		specify the timeout in seconds. default 2 seconds.
1012
1013- U-Boot Version:
1014		CONFIG_VERSION_VARIABLE
1015		If this variable is defined, an environment variable
1016		named "ver" is created by U-Boot showing the U-Boot
1017		version as printed by the "version" command.
1018		Any change to this variable will be reverted at the
1019		next reset.
1020
1021- Real-Time Clock:
1022
1023		When CONFIG_CMD_DATE is selected, the type of the RTC
1024		has to be selected, too. Define exactly one of the
1025		following options:
1026
1027		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
1028		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
1029		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
1030		CONFIG_RTC_MC146818	- use MC146818 RTC
1031		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
1032		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
1033		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
1034		CONFIG_RTC_DS1339	- use Maxim, Inc. DS1339 RTC
1035		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
1036		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
1037		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
1038		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
1039		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
1040					  RV3029 RTC.
1041
1042		Note that if the RTC uses I2C, then the I2C interface
1043		must also be configured. See I2C Support, below.
1044
1045- GPIO Support:
1046		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
1047
1048		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1049		chip-ngpio pairs that tell the PCA953X driver the number of
1050		pins supported by a particular chip.
1051
1052		Note that if the GPIO device uses I2C, then the I2C interface
1053		must also be configured. See I2C Support, below.
1054
1055- I/O tracing:
1056		When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
1057		accesses and can checksum them or write a list of them out
1058		to memory. See the 'iotrace' command for details. This is
1059		useful for testing device drivers since it can confirm that
1060		the driver behaves the same way before and after a code
1061		change. Currently this is supported on sandbox and arm. To
1062		add support for your architecture, add '#include <iotrace.h>'
1063		to the bottom of arch/<arch>/include/asm/io.h and test.
1064
1065		Example output from the 'iotrace stats' command is below.
1066		Note that if the trace buffer is exhausted, the checksum will
1067		still continue to operate.
1068
1069			iotrace is enabled
1070			Start:  10000000	(buffer start address)
1071			Size:   00010000	(buffer size)
1072			Offset: 00000120	(current buffer offset)
1073			Output: 10000120	(start + offset)
1074			Count:  00000018	(number of trace records)
1075			CRC32:  9526fb66	(CRC32 of all trace records)
1076
1077- Timestamp Support:
1078
1079		When CONFIG_TIMESTAMP is selected, the timestamp
1080		(date and time) of an image is printed by image
1081		commands like bootm or iminfo. This option is
1082		automatically enabled when you select CONFIG_CMD_DATE .
1083
1084- Partition Labels (disklabels) Supported:
1085		Zero or more of the following:
1086		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1087		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1088				       Intel architecture, USB sticks, etc.
1089		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1090		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1091				       bootloader.  Note 2TB partition limit; see
1092				       disk/part_efi.c
1093		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1094
1095		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1096		CONFIG_SCSI) you must configure support for at
1097		least one non-MTD partition type as well.
1098
1099- IDE Reset method:
1100		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1101		board configurations files but used nowhere!
1102
1103		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1104		be performed by calling the function
1105			ide_set_reset(int reset)
1106		which has to be defined in a board specific file
1107
1108- ATAPI Support:
1109		CONFIG_ATAPI
1110
1111		Set this to enable ATAPI support.
1112
1113- LBA48 Support
1114		CONFIG_LBA48
1115
1116		Set this to enable support for disks larger than 137GB
1117		Also look at CONFIG_SYS_64BIT_LBA.
1118		Whithout these , LBA48 support uses 32bit variables and will 'only'
1119		support disks up to 2.1TB.
1120
1121		CONFIG_SYS_64BIT_LBA:
1122			When enabled, makes the IDE subsystem use 64bit sector addresses.
1123			Default is 32bit.
1124
1125- SCSI Support:
1126		At the moment only there is only support for the
1127		SYM53C8XX SCSI controller; define
1128		CONFIG_SCSI_SYM53C8XX to enable it.
1129
1130		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1131		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1132		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1133		maximum numbers of LUNs, SCSI ID's and target
1134		devices.
1135		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1136
1137		The environment variable 'scsidevs' is set to the number of
1138		SCSI devices found during the last scan.
1139
1140- NETWORK Support (PCI):
1141		CONFIG_E1000
1142		Support for Intel 8254x/8257x gigabit chips.
1143
1144		CONFIG_E1000_SPI
1145		Utility code for direct access to the SPI bus on Intel 8257x.
1146		This does not do anything useful unless you set at least one
1147		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1148
1149		CONFIG_E1000_SPI_GENERIC
1150		Allow generic access to the SPI bus on the Intel 8257x, for
1151		example with the "sspi" command.
1152
1153		CONFIG_CMD_E1000
1154		Management command for E1000 devices.  When used on devices
1155		with SPI support you can reprogram the EEPROM from U-Boot.
1156
1157		CONFIG_EEPRO100
1158		Support for Intel 82557/82559/82559ER chips.
1159		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1160		write routine for first time initialisation.
1161
1162		CONFIG_TULIP
1163		Support for Digital 2114x chips.
1164		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1165		modem chip initialisation (KS8761/QS6611).
1166
1167		CONFIG_NATSEMI
1168		Support for National dp83815 chips.
1169
1170		CONFIG_NS8382X
1171		Support for National dp8382[01] gigabit chips.
1172
1173- NETWORK Support (other):
1174
1175		CONFIG_DRIVER_AT91EMAC
1176		Support for AT91RM9200 EMAC.
1177
1178			CONFIG_RMII
1179			Define this to use reduced MII inteface
1180
1181			CONFIG_DRIVER_AT91EMAC_QUIET
1182			If this defined, the driver is quiet.
1183			The driver doen't show link status messages.
1184
1185		CONFIG_CALXEDA_XGMAC
1186		Support for the Calxeda XGMAC device
1187
1188		CONFIG_LAN91C96
1189		Support for SMSC's LAN91C96 chips.
1190
1191			CONFIG_LAN91C96_USE_32_BIT
1192			Define this to enable 32 bit addressing
1193
1194		CONFIG_SMC91111
1195		Support for SMSC's LAN91C111 chip
1196
1197			CONFIG_SMC91111_BASE
1198			Define this to hold the physical address
1199			of the device (I/O space)
1200
1201			CONFIG_SMC_USE_32_BIT
1202			Define this if data bus is 32 bits
1203
1204			CONFIG_SMC_USE_IOFUNCS
1205			Define this to use i/o functions instead of macros
1206			(some hardware wont work with macros)
1207
1208		CONFIG_DRIVER_TI_EMAC
1209		Support for davinci emac
1210
1211			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1212			Define this if you have more then 3 PHYs.
1213
1214		CONFIG_FTGMAC100
1215		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1216
1217			CONFIG_FTGMAC100_EGIGA
1218			Define this to use GE link update with gigabit PHY.
1219			Define this if FTGMAC100 is connected to gigabit PHY.
1220			If your system has 10/100 PHY only, it might not occur
1221			wrong behavior. Because PHY usually return timeout or
1222			useless data when polling gigabit status and gigabit
1223			control registers. This behavior won't affect the
1224			correctnessof 10/100 link speed update.
1225
1226		CONFIG_SMC911X
1227		Support for SMSC's LAN911x and LAN921x chips
1228
1229			CONFIG_SMC911X_BASE
1230			Define this to hold the physical address
1231			of the device (I/O space)
1232
1233			CONFIG_SMC911X_32_BIT
1234			Define this if data bus is 32 bits
1235
1236			CONFIG_SMC911X_16_BIT
1237			Define this if data bus is 16 bits. If your processor
1238			automatically converts one 32 bit word to two 16 bit
1239			words you may also try CONFIG_SMC911X_32_BIT.
1240
1241		CONFIG_SH_ETHER
1242		Support for Renesas on-chip Ethernet controller
1243
1244			CONFIG_SH_ETHER_USE_PORT
1245			Define the number of ports to be used
1246
1247			CONFIG_SH_ETHER_PHY_ADDR
1248			Define the ETH PHY's address
1249
1250			CONFIG_SH_ETHER_CACHE_WRITEBACK
1251			If this option is set, the driver enables cache flush.
1252
1253- PWM Support:
1254		CONFIG_PWM_IMX
1255		Support for PWM module on the imx6.
1256
1257- TPM Support:
1258		CONFIG_TPM
1259		Support TPM devices.
1260
1261		CONFIG_TPM_TIS_INFINEON
1262		Support for Infineon i2c bus TPM devices. Only one device
1263		per system is supported at this time.
1264
1265			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1266			Define the burst count bytes upper limit
1267
1268		CONFIG_TPM_ST33ZP24
1269		Support for STMicroelectronics TPM devices. Requires DM_TPM support.
1270
1271			CONFIG_TPM_ST33ZP24_I2C
1272			Support for STMicroelectronics ST33ZP24 I2C devices.
1273			Requires TPM_ST33ZP24 and I2C.
1274
1275			CONFIG_TPM_ST33ZP24_SPI
1276			Support for STMicroelectronics ST33ZP24 SPI devices.
1277			Requires TPM_ST33ZP24 and SPI.
1278
1279		CONFIG_TPM_ATMEL_TWI
1280		Support for Atmel TWI TPM device. Requires I2C support.
1281
1282		CONFIG_TPM_TIS_LPC
1283		Support for generic parallel port TPM devices. Only one device
1284		per system is supported at this time.
1285
1286			CONFIG_TPM_TIS_BASE_ADDRESS
1287			Base address where the generic TPM device is mapped
1288			to. Contemporary x86 systems usually map it at
1289			0xfed40000.
1290
1291		CONFIG_CMD_TPM
1292		Add tpm monitor functions.
1293		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1294		provides monitor access to authorized functions.
1295
1296		CONFIG_TPM
1297		Define this to enable the TPM support library which provides
1298		functional interfaces to some TPM commands.
1299		Requires support for a TPM device.
1300
1301		CONFIG_TPM_AUTH_SESSIONS
1302		Define this to enable authorized functions in the TPM library.
1303		Requires CONFIG_TPM and CONFIG_SHA1.
1304
1305- USB Support:
1306		At the moment only the UHCI host controller is
1307		supported (PIP405, MIP405, MPC5200); define
1308		CONFIG_USB_UHCI to enable it.
1309		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1310		and define CONFIG_USB_STORAGE to enable the USB
1311		storage devices.
1312		Note:
1313		Supported are USB Keyboards and USB Floppy drives
1314		(TEAC FD-05PUB).
1315		MPC5200 USB requires additional defines:
1316			CONFIG_USB_CLOCK
1317				for 528 MHz Clock: 0x0001bbbb
1318			CONFIG_PSC3_USB
1319				for USB on PSC3
1320			CONFIG_USB_CONFIG
1321				for differential drivers: 0x00001000
1322				for single ended drivers: 0x00005000
1323				for differential drivers on PSC3: 0x00000100
1324				for single ended drivers on PSC3: 0x00004100
1325			CONFIG_SYS_USB_EVENT_POLL
1326				May be defined to allow interrupt polling
1327				instead of using asynchronous interrupts
1328
1329		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1330		txfilltuning field in the EHCI controller on reset.
1331
1332		CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
1333		HW module registers.
1334
1335- USB Device:
1336		Define the below if you wish to use the USB console.
1337		Once firmware is rebuilt from a serial console issue the
1338		command "setenv stdin usbtty; setenv stdout usbtty" and
1339		attach your USB cable. The Unix command "dmesg" should print
1340		it has found a new device. The environment variable usbtty
1341		can be set to gserial or cdc_acm to enable your device to
1342		appear to a USB host as a Linux gserial device or a
1343		Common Device Class Abstract Control Model serial device.
1344		If you select usbtty = gserial you should be able to enumerate
1345		a Linux host by
1346		# modprobe usbserial vendor=0xVendorID product=0xProductID
1347		else if using cdc_acm, simply setting the environment
1348		variable usbtty to be cdc_acm should suffice. The following
1349		might be defined in YourBoardName.h
1350
1351			CONFIG_USB_DEVICE
1352			Define this to build a UDC device
1353
1354			CONFIG_USB_TTY
1355			Define this to have a tty type of device available to
1356			talk to the UDC device
1357
1358			CONFIG_USBD_HS
1359			Define this to enable the high speed support for usb
1360			device and usbtty. If this feature is enabled, a routine
1361			int is_usbd_high_speed(void)
1362			also needs to be defined by the driver to dynamically poll
1363			whether the enumeration has succeded at high speed or full
1364			speed.
1365
1366			CONFIG_SYS_CONSOLE_IS_IN_ENV
1367			Define this if you want stdin, stdout &/or stderr to
1368			be set to usbtty.
1369
1370			mpc8xx:
1371				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1372				Derive USB clock from external clock "blah"
1373				- CONFIG_SYS_USB_EXTC_CLK 0x02
1374
1375		If you have a USB-IF assigned VendorID then you may wish to
1376		define your own vendor specific values either in BoardName.h
1377		or directly in usbd_vendor_info.h. If you don't define
1378		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1379		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1380		should pretend to be a Linux device to it's target host.
1381
1382			CONFIG_USBD_MANUFACTURER
1383			Define this string as the name of your company for
1384			- CONFIG_USBD_MANUFACTURER "my company"
1385
1386			CONFIG_USBD_PRODUCT_NAME
1387			Define this string as the name of your product
1388			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1389
1390			CONFIG_USBD_VENDORID
1391			Define this as your assigned Vendor ID from the USB
1392			Implementors Forum. This *must* be a genuine Vendor ID
1393			to avoid polluting the USB namespace.
1394			- CONFIG_USBD_VENDORID 0xFFFF
1395
1396			CONFIG_USBD_PRODUCTID
1397			Define this as the unique Product ID
1398			for your device
1399			- CONFIG_USBD_PRODUCTID 0xFFFF
1400
1401- ULPI Layer Support:
1402		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1403		the generic ULPI layer. The generic layer accesses the ULPI PHY
1404		via the platform viewport, so you need both the genric layer and
1405		the viewport enabled. Currently only Chipidea/ARC based
1406		viewport is supported.
1407		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1408		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1409		If your ULPI phy needs a different reference clock than the
1410		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1411		the appropriate value in Hz.
1412
1413- MMC Support:
1414		The MMC controller on the Intel PXA is supported. To
1415		enable this define CONFIG_MMC. The MMC can be
1416		accessed from the boot prompt by mapping the device
1417		to physical memory similar to flash. Command line is
1418		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1419		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1420
1421		CONFIG_SH_MMCIF
1422		Support for Renesas on-chip MMCIF controller
1423
1424			CONFIG_SH_MMCIF_ADDR
1425			Define the base address of MMCIF registers
1426
1427			CONFIG_SH_MMCIF_CLK
1428			Define the clock frequency for MMCIF
1429
1430		CONFIG_SUPPORT_EMMC_BOOT
1431		Enable some additional features of the eMMC boot partitions.
1432
1433		CONFIG_SUPPORT_EMMC_RPMB
1434		Enable the commands for reading, writing and programming the
1435		key for the Replay Protection Memory Block partition in eMMC.
1436
1437- USB Device Firmware Update (DFU) class support:
1438		CONFIG_USB_FUNCTION_DFU
1439		This enables the USB portion of the DFU USB class
1440
1441		CONFIG_CMD_DFU
1442		This enables the command "dfu" which is used to have
1443		U-Boot create a DFU class device via USB.  This command
1444		requires that the "dfu_alt_info" environment variable be
1445		set and define the alt settings to expose to the host.
1446
1447		CONFIG_DFU_MMC
1448		This enables support for exposing (e)MMC devices via DFU.
1449
1450		CONFIG_DFU_NAND
1451		This enables support for exposing NAND devices via DFU.
1452
1453		CONFIG_DFU_RAM
1454		This enables support for exposing RAM via DFU.
1455		Note: DFU spec refer to non-volatile memory usage, but
1456		allow usages beyond the scope of spec - here RAM usage,
1457		one that would help mostly the developer.
1458
1459		CONFIG_SYS_DFU_DATA_BUF_SIZE
1460		Dfu transfer uses a buffer before writing data to the
1461		raw storage device. Make the size (in bytes) of this buffer
1462		configurable. The size of this buffer is also configurable
1463		through the "dfu_bufsiz" environment variable.
1464
1465		CONFIG_SYS_DFU_MAX_FILE_SIZE
1466		When updating files rather than the raw storage device,
1467		we use a static buffer to copy the file into and then write
1468		the buffer once we've been given the whole file.  Define
1469		this to the maximum filesize (in bytes) for the buffer.
1470		Default is 4 MiB if undefined.
1471
1472		DFU_DEFAULT_POLL_TIMEOUT
1473		Poll timeout [ms], is the timeout a device can send to the
1474		host. The host must wait for this timeout before sending
1475		a subsequent DFU_GET_STATUS request to the device.
1476
1477		DFU_MANIFEST_POLL_TIMEOUT
1478		Poll timeout [ms], which the device sends to the host when
1479		entering dfuMANIFEST state. Host waits this timeout, before
1480		sending again an USB request to the device.
1481
1482- USB Device Android Fastboot support:
1483		CONFIG_USB_FUNCTION_FASTBOOT
1484		This enables the USB part of the fastboot gadget
1485
1486		CONFIG_CMD_FASTBOOT
1487		This enables the command "fastboot" which enables the Android
1488		fastboot mode for the platform's USB device. Fastboot is a USB
1489		protocol for downloading images, flashing and device control
1490		used on Android devices.
1491		See doc/README.android-fastboot for more information.
1492
1493		CONFIG_ANDROID_BOOT_IMAGE
1494		This enables support for booting images which use the Android
1495		image format header.
1496
1497		CONFIG_FASTBOOT_BUF_ADDR
1498		The fastboot protocol requires a large memory buffer for
1499		downloads. Define this to the starting RAM address to use for
1500		downloaded images.
1501
1502		CONFIG_FASTBOOT_BUF_SIZE
1503		The fastboot protocol requires a large memory buffer for
1504		downloads. This buffer should be as large as possible for a
1505		platform. Define this to the size available RAM for fastboot.
1506
1507		CONFIG_FASTBOOT_FLASH
1508		The fastboot protocol includes a "flash" command for writing
1509		the downloaded image to a non-volatile storage device. Define
1510		this to enable the "fastboot flash" command.
1511
1512		CONFIG_FASTBOOT_FLASH_MMC_DEV
1513		The fastboot "flash" command requires additional information
1514		regarding the non-volatile storage device. Define this to
1515		the eMMC device that fastboot should use to store the image.
1516
1517		CONFIG_FASTBOOT_GPT_NAME
1518		The fastboot "flash" command supports writing the downloaded
1519		image to the Protective MBR and the Primary GUID Partition
1520		Table. (Additionally, this downloaded image is post-processed
1521		to generate and write the Backup GUID Partition Table.)
1522		This occurs when the specified "partition name" on the
1523		"fastboot flash" command line matches this value.
1524		The default is "gpt" if undefined.
1525
1526		CONFIG_FASTBOOT_MBR_NAME
1527		The fastboot "flash" command supports writing the downloaded
1528		image to DOS MBR.
1529		This occurs when the "partition name" specified on the
1530		"fastboot flash" command line matches this value.
1531		If not defined the default value "mbr" is used.
1532
1533- Journaling Flash filesystem support:
1534		CONFIG_JFFS2_NAND
1535		Define these for a default partition on a NAND device
1536
1537		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1538		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1539		Define these for a default partition on a NOR device
1540
1541- FAT(File Allocation Table) filesystem write function support:
1542		CONFIG_FAT_WRITE
1543
1544		Define this to enable support for saving memory data as a
1545		file in FAT formatted partition.
1546
1547		This will also enable the command "fatwrite" enabling the
1548		user to write files to FAT.
1549
1550- FAT(File Allocation Table) filesystem cluster size:
1551		CONFIG_FS_FAT_MAX_CLUSTSIZE
1552
1553		Define the max cluster size for fat operations else
1554		a default value of 65536 will be defined.
1555
1556- Keyboard Support:
1557		See Kconfig help for available keyboard drivers.
1558
1559		CONFIG_KEYBOARD
1560
1561		Define this to enable a custom keyboard support.
1562		This simply calls drv_keyboard_init() which must be
1563		defined in your board-specific files. This option is deprecated
1564		and is only used by novena. For new boards, use driver model
1565		instead.
1566
1567- Video support:
1568		CONFIG_FSL_DIU_FB
1569		Enable the Freescale DIU video driver.	Reference boards for
1570		SOCs that have a DIU should define this macro to enable DIU
1571		support, and should also define these other macros:
1572
1573			CONFIG_SYS_DIU_ADDR
1574			CONFIG_VIDEO
1575			CONFIG_CFB_CONSOLE
1576			CONFIG_VIDEO_SW_CURSOR
1577			CONFIG_VGA_AS_SINGLE_DEVICE
1578			CONFIG_VIDEO_LOGO
1579			CONFIG_VIDEO_BMP_LOGO
1580
1581		The DIU driver will look for the 'video-mode' environment
1582		variable, and if defined, enable the DIU as a console during
1583		boot.  See the documentation file doc/README.video for a
1584		description of this variable.
1585
1586- LCD Support:	CONFIG_LCD
1587
1588		Define this to enable LCD support (for output to LCD
1589		display); also select one of the supported displays
1590		by defining one of these:
1591
1592		CONFIG_ATMEL_LCD:
1593
1594			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1595
1596		CONFIG_NEC_NL6448AC33:
1597
1598			NEC NL6448AC33-18. Active, color, single scan.
1599
1600		CONFIG_NEC_NL6448BC20
1601
1602			NEC NL6448BC20-08. 6.5", 640x480.
1603			Active, color, single scan.
1604
1605		CONFIG_NEC_NL6448BC33_54
1606
1607			NEC NL6448BC33-54. 10.4", 640x480.
1608			Active, color, single scan.
1609
1610		CONFIG_SHARP_16x9
1611
1612			Sharp 320x240. Active, color, single scan.
1613			It isn't 16x9, and I am not sure what it is.
1614
1615		CONFIG_SHARP_LQ64D341
1616
1617			Sharp LQ64D341 display, 640x480.
1618			Active, color, single scan.
1619
1620		CONFIG_HLD1045
1621
1622			HLD1045 display, 640x480.
1623			Active, color, single scan.
1624
1625		CONFIG_OPTREX_BW
1626
1627			Optrex	 CBL50840-2 NF-FW 99 22 M5
1628			or
1629			Hitachi	 LMG6912RPFC-00T
1630			or
1631			Hitachi	 SP14Q002
1632
1633			320x240. Black & white.
1634
1635		CONFIG_LCD_ALIGNMENT
1636
1637		Normally the LCD is page-aligned (typically 4KB). If this is
1638		defined then the LCD will be aligned to this value instead.
1639		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1640		here, since it is cheaper to change data cache settings on
1641		a per-section basis.
1642
1643
1644		CONFIG_LCD_ROTATION
1645
1646		Sometimes, for example if the display is mounted in portrait
1647		mode or even if it's mounted landscape but rotated by 180degree,
1648		we need to rotate our content of the display relative to the
1649		framebuffer, so that user can read the messages which are
1650		printed out.
1651		Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1652		initialized with a given rotation from "vl_rot" out of
1653		"vidinfo_t" which is provided by the board specific code.
1654		The value for vl_rot is coded as following (matching to
1655		fbcon=rotate:<n> linux-kernel commandline):
1656		0 = no rotation respectively 0 degree
1657		1 = 90 degree rotation
1658		2 = 180 degree rotation
1659		3 = 270 degree rotation
1660
1661		If CONFIG_LCD_ROTATION is not defined, the console will be
1662		initialized with 0degree rotation.
1663
1664		CONFIG_LCD_BMP_RLE8
1665
1666		Support drawing of RLE8-compressed bitmaps on the LCD.
1667
1668		CONFIG_I2C_EDID
1669
1670		Enables an 'i2c edid' command which can read EDID
1671		information over I2C from an attached LCD display.
1672
1673- Splash Screen Support: CONFIG_SPLASH_SCREEN
1674
1675		If this option is set, the environment is checked for
1676		a variable "splashimage". If found, the usual display
1677		of logo, copyright and system information on the LCD
1678		is suppressed and the BMP image at the address
1679		specified in "splashimage" is loaded instead. The
1680		console is redirected to the "nulldev", too. This
1681		allows for a "silent" boot where a splash screen is
1682		loaded very quickly after power-on.
1683
1684		CONFIG_SPLASHIMAGE_GUARD
1685
1686		If this option is set, then U-Boot will prevent the environment
1687		variable "splashimage" from being set to a problematic address
1688		(see doc/README.displaying-bmps).
1689		This option is useful for targets where, due to alignment
1690		restrictions, an improperly aligned BMP image will cause a data
1691		abort. If you think you will not have problems with unaligned
1692		accesses (for example because your toolchain prevents them)
1693		there is no need to set this option.
1694
1695		CONFIG_SPLASH_SCREEN_ALIGN
1696
1697		If this option is set the splash image can be freely positioned
1698		on the screen. Environment variable "splashpos" specifies the
1699		position as "x,y". If a positive number is given it is used as
1700		number of pixel from left/top. If a negative number is given it
1701		is used as number of pixel from right/bottom. You can also
1702		specify 'm' for centering the image.
1703
1704		Example:
1705		setenv splashpos m,m
1706			=> image at center of screen
1707
1708		setenv splashpos 30,20
1709			=> image at x = 30 and y = 20
1710
1711		setenv splashpos -10,m
1712			=> vertically centered image
1713			   at x = dspWidth - bmpWidth - 9
1714
1715- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1716
1717		If this option is set, additionally to standard BMP
1718		images, gzipped BMP images can be displayed via the
1719		splashscreen support or the bmp command.
1720
1721- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1722
1723		If this option is set, 8-bit RLE compressed BMP images
1724		can be displayed via the splashscreen support or the
1725		bmp command.
1726
1727- Compression support:
1728		CONFIG_GZIP
1729
1730		Enabled by default to support gzip compressed images.
1731
1732		CONFIG_BZIP2
1733
1734		If this option is set, support for bzip2 compressed
1735		images is included. If not, only uncompressed and gzip
1736		compressed images are supported.
1737
1738		NOTE: the bzip2 algorithm requires a lot of RAM, so
1739		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1740		be at least 4MB.
1741
1742		CONFIG_LZMA
1743
1744		If this option is set, support for lzma compressed
1745		images is included.
1746
1747		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1748		requires an amount of dynamic memory that is given by the
1749		formula:
1750
1751			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1752
1753		Where lc and lp stand for, respectively, Literal context bits
1754		and Literal pos bits.
1755
1756		This value is upper-bounded by 14MB in the worst case. Anyway,
1757		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1758		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1759		a very small buffer.
1760
1761		Use the lzmainfo tool to determinate the lc and lp values and
1762		then calculate the amount of needed dynamic memory (ensuring
1763		the appropriate CONFIG_SYS_MALLOC_LEN value).
1764
1765		CONFIG_LZO
1766
1767		If this option is set, support for LZO compressed images
1768		is included.
1769
1770- MII/PHY support:
1771		CONFIG_PHY_ADDR
1772
1773		The address of PHY on MII bus.
1774
1775		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1776
1777		The clock frequency of the MII bus
1778
1779		CONFIG_PHY_GIGE
1780
1781		If this option is set, support for speed/duplex
1782		detection of gigabit PHY is included.
1783
1784		CONFIG_PHY_RESET_DELAY
1785
1786		Some PHY like Intel LXT971A need extra delay after
1787		reset before any MII register access is possible.
1788		For such PHY, set this option to the usec delay
1789		required. (minimum 300usec for LXT971A)
1790
1791		CONFIG_PHY_CMD_DELAY (ppc4xx)
1792
1793		Some PHY like Intel LXT971A need extra delay after
1794		command issued before MII status register can be read
1795
1796- IP address:
1797		CONFIG_IPADDR
1798
1799		Define a default value for the IP address to use for
1800		the default Ethernet interface, in case this is not
1801		determined through e.g. bootp.
1802		(Environment variable "ipaddr")
1803
1804- Server IP address:
1805		CONFIG_SERVERIP
1806
1807		Defines a default value for the IP address of a TFTP
1808		server to contact when using the "tftboot" command.
1809		(Environment variable "serverip")
1810
1811		CONFIG_KEEP_SERVERADDR
1812
1813		Keeps the server's MAC address, in the env 'serveraddr'
1814		for passing to bootargs (like Linux's netconsole option)
1815
1816- Gateway IP address:
1817		CONFIG_GATEWAYIP
1818
1819		Defines a default value for the IP address of the
1820		default router where packets to other networks are
1821		sent to.
1822		(Environment variable "gatewayip")
1823
1824- Subnet mask:
1825		CONFIG_NETMASK
1826
1827		Defines a default value for the subnet mask (or
1828		routing prefix) which is used to determine if an IP
1829		address belongs to the local subnet or needs to be
1830		forwarded through a router.
1831		(Environment variable "netmask")
1832
1833- Multicast TFTP Mode:
1834		CONFIG_MCAST_TFTP
1835
1836		Defines whether you want to support multicast TFTP as per
1837		rfc-2090; for example to work with atftp.  Lets lots of targets
1838		tftp down the same boot image concurrently.  Note: the Ethernet
1839		driver in use must provide a function: mcast() to join/leave a
1840		multicast group.
1841
1842- BOOTP Recovery Mode:
1843		CONFIG_BOOTP_RANDOM_DELAY
1844
1845		If you have many targets in a network that try to
1846		boot using BOOTP, you may want to avoid that all
1847		systems send out BOOTP requests at precisely the same
1848		moment (which would happen for instance at recovery
1849		from a power failure, when all systems will try to
1850		boot, thus flooding the BOOTP server. Defining
1851		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1852		inserted before sending out BOOTP requests. The
1853		following delays are inserted then:
1854
1855		1st BOOTP request:	delay 0 ... 1 sec
1856		2nd BOOTP request:	delay 0 ... 2 sec
1857		3rd BOOTP request:	delay 0 ... 4 sec
1858		4th and following
1859		BOOTP requests:		delay 0 ... 8 sec
1860
1861		CONFIG_BOOTP_ID_CACHE_SIZE
1862
1863		BOOTP packets are uniquely identified using a 32-bit ID. The
1864		server will copy the ID from client requests to responses and
1865		U-Boot will use this to determine if it is the destination of
1866		an incoming response. Some servers will check that addresses
1867		aren't in use before handing them out (usually using an ARP
1868		ping) and therefore take up to a few hundred milliseconds to
1869		respond. Network congestion may also influence the time it
1870		takes for a response to make it back to the client. If that
1871		time is too long, U-Boot will retransmit requests. In order
1872		to allow earlier responses to still be accepted after these
1873		retransmissions, U-Boot's BOOTP client keeps a small cache of
1874		IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1875		cache. The default is to keep IDs for up to four outstanding
1876		requests. Increasing this will allow U-Boot to accept offers
1877		from a BOOTP client in networks with unusually high latency.
1878
1879- DHCP Advanced Options:
1880		You can fine tune the DHCP functionality by defining
1881		CONFIG_BOOTP_* symbols:
1882
1883		CONFIG_BOOTP_SUBNETMASK
1884		CONFIG_BOOTP_GATEWAY
1885		CONFIG_BOOTP_HOSTNAME
1886		CONFIG_BOOTP_NISDOMAIN
1887		CONFIG_BOOTP_BOOTPATH
1888		CONFIG_BOOTP_BOOTFILESIZE
1889		CONFIG_BOOTP_DNS
1890		CONFIG_BOOTP_DNS2
1891		CONFIG_BOOTP_SEND_HOSTNAME
1892		CONFIG_BOOTP_NTPSERVER
1893		CONFIG_BOOTP_TIMEOFFSET
1894		CONFIG_BOOTP_VENDOREX
1895		CONFIG_BOOTP_MAY_FAIL
1896
1897		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1898		environment variable, not the BOOTP server.
1899
1900		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1901		after the configured retry count, the call will fail
1902		instead of starting over.  This can be used to fail over
1903		to Link-local IP address configuration if the DHCP server
1904		is not available.
1905
1906		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1907		serverip from a DHCP server, it is possible that more
1908		than one DNS serverip is offered to the client.
1909		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1910		serverip will be stored in the additional environment
1911		variable "dnsip2". The first DNS serverip is always
1912		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1913		is defined.
1914
1915		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1916		to do a dynamic update of a DNS server. To do this, they
1917		need the hostname of the DHCP requester.
1918		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1919		of the "hostname" environment variable is passed as
1920		option 12 to the DHCP server.
1921
1922		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1923
1924		A 32bit value in microseconds for a delay between
1925		receiving a "DHCP Offer" and sending the "DHCP Request".
1926		This fixes a problem with certain DHCP servers that don't
1927		respond 100% of the time to a "DHCP request". E.g. On an
1928		AT91RM9200 processor running at 180MHz, this delay needed
1929		to be *at least* 15,000 usec before a Windows Server 2003
1930		DHCP server would reply 100% of the time. I recommend at
1931		least 50,000 usec to be safe. The alternative is to hope
1932		that one of the retries will be successful but note that
1933		the DHCP timeout and retry process takes a longer than
1934		this delay.
1935
1936 - Link-local IP address negotiation:
1937		Negotiate with other link-local clients on the local network
1938		for an address that doesn't require explicit configuration.
1939		This is especially useful if a DHCP server cannot be guaranteed
1940		to exist in all environments that the device must operate.
1941
1942		See doc/README.link-local for more information.
1943
1944 - CDP Options:
1945		CONFIG_CDP_DEVICE_ID
1946
1947		The device id used in CDP trigger frames.
1948
1949		CONFIG_CDP_DEVICE_ID_PREFIX
1950
1951		A two character string which is prefixed to the MAC address
1952		of the device.
1953
1954		CONFIG_CDP_PORT_ID
1955
1956		A printf format string which contains the ascii name of
1957		the port. Normally is set to "eth%d" which sets
1958		eth0 for the first Ethernet, eth1 for the second etc.
1959
1960		CONFIG_CDP_CAPABILITIES
1961
1962		A 32bit integer which indicates the device capabilities;
1963		0x00000010 for a normal host which does not forwards.
1964
1965		CONFIG_CDP_VERSION
1966
1967		An ascii string containing the version of the software.
1968
1969		CONFIG_CDP_PLATFORM
1970
1971		An ascii string containing the name of the platform.
1972
1973		CONFIG_CDP_TRIGGER
1974
1975		A 32bit integer sent on the trigger.
1976
1977		CONFIG_CDP_POWER_CONSUMPTION
1978
1979		A 16bit integer containing the power consumption of the
1980		device in .1 of milliwatts.
1981
1982		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1983
1984		A byte containing the id of the VLAN.
1985
1986- Status LED:	CONFIG_LED_STATUS
1987
1988		Several configurations allow to display the current
1989		status using a LED. For instance, the LED will blink
1990		fast while running U-Boot code, stop blinking as
1991		soon as a reply to a BOOTP request was received, and
1992		start blinking slow once the Linux kernel is running
1993		(supported by a status LED driver in the Linux
1994		kernel). Defining CONFIG_LED_STATUS enables this
1995		feature in U-Boot.
1996
1997		Additional options:
1998
1999		CONFIG_LED_STATUS_GPIO
2000		The status LED can be connected to a GPIO pin.
2001		In such cases, the gpio_led driver can be used as a
2002		status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
2003		to include the gpio_led driver in the U-Boot binary.
2004
2005		CONFIG_GPIO_LED_INVERTED_TABLE
2006		Some GPIO connected LEDs may have inverted polarity in which
2007		case the GPIO high value corresponds to LED off state and
2008		GPIO low value corresponds to LED on state.
2009		In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
2010		with a list of GPIO LEDs that have inverted polarity.
2011
2012- CAN Support:	CONFIG_CAN_DRIVER
2013
2014		Defining CONFIG_CAN_DRIVER enables CAN driver support
2015		on those systems that support this (optional)
2016		feature, like the TQM8xxL modules.
2017
2018- I2C Support:	CONFIG_SYS_I2C
2019
2020		This enable the NEW i2c subsystem, and will allow you to use
2021		i2c commands at the u-boot command line (as long as you set
2022		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
2023		based realtime clock chips or other i2c devices. See
2024		common/cmd_i2c.c for a description of the command line
2025		interface.
2026
2027		ported i2c driver to the new framework:
2028		- drivers/i2c/soft_i2c.c:
2029		  - activate first bus with CONFIG_SYS_I2C_SOFT define
2030		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
2031		    for defining speed and slave address
2032		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
2033		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
2034		    for defining speed and slave address
2035		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
2036		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
2037		    for defining speed and slave address
2038		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
2039		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
2040		    for defining speed and slave address
2041
2042		- drivers/i2c/fsl_i2c.c:
2043		  - activate i2c driver with CONFIG_SYS_I2C_FSL
2044		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
2045		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
2046		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
2047		    bus.
2048		  - If your board supports a second fsl i2c bus, define
2049		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
2050		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
2051		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
2052		    second bus.
2053
2054		- drivers/i2c/tegra_i2c.c:
2055		  - activate this driver with CONFIG_SYS_I2C_TEGRA
2056		  - This driver adds 4 i2c buses with a fix speed from
2057		    100000 and the slave addr 0!
2058
2059		- drivers/i2c/ppc4xx_i2c.c
2060		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
2061		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
2062		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
2063
2064		- drivers/i2c/i2c_mxc.c
2065		  - activate this driver with CONFIG_SYS_I2C_MXC
2066		  - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1
2067		  - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2
2068		  - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3
2069		  - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4
2070		  - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
2071		  - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
2072		  - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
2073		  - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
2074		  - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
2075		  - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
2076		  - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED
2077		  - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE
2078		If those defines are not set, default value is 100000
2079		for speed, and 0 for slave.
2080
2081		- drivers/i2c/rcar_i2c.c:
2082		  - activate this driver with CONFIG_SYS_I2C_RCAR
2083		  - This driver adds 4 i2c buses
2084
2085		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
2086		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
2087		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
2088		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
2089		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
2090		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
2091		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
2092		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
2093		  - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
2094
2095		- drivers/i2c/sh_i2c.c:
2096		  - activate this driver with CONFIG_SYS_I2C_SH
2097		  - This driver adds from 2 to 5 i2c buses
2098
2099		  - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
2100		  - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
2101		  - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
2102		  - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
2103		  - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
2104		  - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
2105		  - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
2106		  - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
2107		  - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
2108		  - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
2109		  - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses
2110
2111		- drivers/i2c/omap24xx_i2c.c
2112		  - activate this driver with CONFIG_SYS_I2C_OMAP24XX
2113		  - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
2114		  - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
2115		  - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
2116		  - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
2117		  - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
2118		  - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
2119		  - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
2120		  - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
2121		  - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
2122		  - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
2123
2124		- drivers/i2c/zynq_i2c.c
2125		  - activate this driver with CONFIG_SYS_I2C_ZYNQ
2126		  - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
2127		  - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
2128
2129		- drivers/i2c/s3c24x0_i2c.c:
2130		  - activate this driver with CONFIG_SYS_I2C_S3C24X0
2131		  - This driver adds i2c buses (11 for Exynos5250, Exynos5420
2132		    9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
2133		    with a fix speed from 100000 and the slave addr 0!
2134
2135		- drivers/i2c/ihs_i2c.c
2136		  - activate this driver with CONFIG_SYS_I2C_IHS
2137		  - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
2138		  - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
2139		  - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
2140		  - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
2141		  - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
2142		  - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
2143		  - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
2144		  - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
2145		  - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
2146		  - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
2147		  - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
2148		  - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3
2149		  - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL
2150		  - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1
2151		  - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1
2152		  - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1
2153		  - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1
2154		  - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1
2155		  - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1
2156		  - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1
2157		  - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1
2158
2159		additional defines:
2160
2161		CONFIG_SYS_NUM_I2C_BUSES
2162		Hold the number of i2c buses you want to use.
2163
2164		CONFIG_SYS_I2C_DIRECT_BUS
2165		define this, if you don't use i2c muxes on your hardware.
2166		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2167		omit this define.
2168
2169		CONFIG_SYS_I2C_MAX_HOPS
2170		define how many muxes are maximal consecutively connected
2171		on one i2c bus. If you not use i2c muxes, omit this
2172		define.
2173
2174		CONFIG_SYS_I2C_BUSES
2175		hold a list of buses you want to use, only used if
2176		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2177		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2178		CONFIG_SYS_NUM_I2C_BUSES = 9:
2179
2180		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
2181					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2182					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2183					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2184					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2185					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2186					{1, {I2C_NULL_HOP}}, \
2187					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2188					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2189					}
2190
2191		which defines
2192			bus 0 on adapter 0 without a mux
2193			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2194			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2195			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2196			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2197			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2198			bus 6 on adapter 1 without a mux
2199			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2200			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2201
2202		If you do not have i2c muxes on your board, omit this define.
2203
2204- Legacy I2C Support:
2205		If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2206		then the following macros need to be defined (examples are
2207		from include/configs/lwmon.h):
2208
2209		I2C_INIT
2210
2211		(Optional). Any commands necessary to enable the I2C
2212		controller or configure ports.
2213
2214		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2215
2216		I2C_PORT
2217
2218		(Only for MPC8260 CPU). The I/O port to use (the code
2219		assumes both bits are on the same port). Valid values
2220		are 0..3 for ports A..D.
2221
2222		I2C_ACTIVE
2223
2224		The code necessary to make the I2C data line active
2225		(driven).  If the data line is open collector, this
2226		define can be null.
2227
2228		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2229
2230		I2C_TRISTATE
2231
2232		The code necessary to make the I2C data line tri-stated
2233		(inactive).  If the data line is open collector, this
2234		define can be null.
2235
2236		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2237
2238		I2C_READ
2239
2240		Code that returns true if the I2C data line is high,
2241		false if it is low.
2242
2243		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2244
2245		I2C_SDA(bit)
2246
2247		If <bit> is true, sets the I2C data line high. If it
2248		is false, it clears it (low).
2249
2250		eg: #define I2C_SDA(bit) \
2251			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2252			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2253
2254		I2C_SCL(bit)
2255
2256		If <bit> is true, sets the I2C clock line high. If it
2257		is false, it clears it (low).
2258
2259		eg: #define I2C_SCL(bit) \
2260			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2261			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2262
2263		I2C_DELAY
2264
2265		This delay is invoked four times per clock cycle so this
2266		controls the rate of data transfer.  The data rate thus
2267		is 1 / (I2C_DELAY * 4). Often defined to be something
2268		like:
2269
2270		#define I2C_DELAY  udelay(2)
2271
2272		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2273
2274		If your arch supports the generic GPIO framework (asm/gpio.h),
2275		then you may alternatively define the two GPIOs that are to be
2276		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2277		have GPIO-based defaults assigned to them as appropriate.
2278
2279		You should define these to the GPIO value as given directly to
2280		the generic GPIO functions.
2281
2282		CONFIG_SYS_I2C_INIT_BOARD
2283
2284		When a board is reset during an i2c bus transfer
2285		chips might think that the current transfer is still
2286		in progress. On some boards it is possible to access
2287		the i2c SCLK line directly, either by using the
2288		processor pin as a GPIO or by having a second pin
2289		connected to the bus. If this option is defined a
2290		custom i2c_init_board() routine in boards/xxx/board.c
2291		is run early in the boot sequence.
2292
2293		CONFIG_I2C_MULTI_BUS
2294
2295		This option allows the use of multiple I2C buses, each of which
2296		must have a controller.	 At any point in time, only one bus is
2297		active.	 To switch to a different bus, use the 'i2c dev' command.
2298		Note that bus numbering is zero-based.
2299
2300		CONFIG_SYS_I2C_NOPROBES
2301
2302		This option specifies a list of I2C devices that will be skipped
2303		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2304		is set, specify a list of bus-device pairs.  Otherwise, specify
2305		a 1D array of device addresses
2306
2307		e.g.
2308			#undef	CONFIG_I2C_MULTI_BUS
2309			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2310
2311		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2312
2313			#define CONFIG_I2C_MULTI_BUS
2314			#define CONFIG_SYS_I2C_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2315
2316		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2317
2318		CONFIG_SYS_SPD_BUS_NUM
2319
2320		If defined, then this indicates the I2C bus number for DDR SPD.
2321		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2322
2323		CONFIG_SYS_RTC_BUS_NUM
2324
2325		If defined, then this indicates the I2C bus number for the RTC.
2326		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2327
2328		CONFIG_SYS_DTT_BUS_NUM
2329
2330		If defined, then this indicates the I2C bus number for the DTT.
2331		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2332
2333		CONFIG_SYS_I2C_DTT_ADDR:
2334
2335		If defined, specifies the I2C address of the DTT device.
2336		If not defined, then U-Boot uses predefined value for
2337		specified DTT device.
2338
2339		CONFIG_SOFT_I2C_READ_REPEATED_START
2340
2341		defining this will force the i2c_read() function in
2342		the soft_i2c driver to perform an I2C repeated start
2343		between writing the address pointer and reading the
2344		data.  If this define is omitted the default behaviour
2345		of doing a stop-start sequence will be used.  Most I2C
2346		devices can use either method, but some require one or
2347		the other.
2348
2349- SPI Support:	CONFIG_SPI
2350
2351		Enables SPI driver (so far only tested with
2352		SPI EEPROM, also an instance works with Crystal A/D and
2353		D/As on the SACSng board)
2354
2355		CONFIG_SH_SPI
2356
2357		Enables the driver for SPI controller on SuperH. Currently
2358		only SH7757 is supported.
2359
2360		CONFIG_SOFT_SPI
2361
2362		Enables a software (bit-bang) SPI driver rather than
2363		using hardware support. This is a general purpose
2364		driver that only requires three general I/O port pins
2365		(two outputs, one input) to function. If this is
2366		defined, the board configuration must define several
2367		SPI configuration items (port pins to use, etc). For
2368		an example, see include/configs/sacsng.h.
2369
2370		CONFIG_HARD_SPI
2371
2372		Enables a hardware SPI driver for general-purpose reads
2373		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2374		must define a list of chip-select function pointers.
2375		Currently supported on some MPC8xxx processors.	 For an
2376		example, see include/configs/mpc8349emds.h.
2377
2378		CONFIG_MXC_SPI
2379
2380		Enables the driver for the SPI controllers on i.MX and MXC
2381		SoCs. Currently i.MX31/35/51 are supported.
2382
2383		CONFIG_SYS_SPI_MXC_WAIT
2384		Timeout for waiting until spi transfer completed.
2385		default: (CONFIG_SYS_HZ/100)     /* 10 ms */
2386
2387- FPGA Support: CONFIG_FPGA
2388
2389		Enables FPGA subsystem.
2390
2391		CONFIG_FPGA_<vendor>
2392
2393		Enables support for specific chip vendors.
2394		(ALTERA, XILINX)
2395
2396		CONFIG_FPGA_<family>
2397
2398		Enables support for FPGA family.
2399		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2400
2401		CONFIG_FPGA_COUNT
2402
2403		Specify the number of FPGA devices to support.
2404
2405		CONFIG_CMD_FPGA_LOADMK
2406
2407		Enable support for fpga loadmk command
2408
2409		CONFIG_CMD_FPGA_LOADP
2410
2411		Enable support for fpga loadp command - load partial bitstream
2412
2413		CONFIG_CMD_FPGA_LOADBP
2414
2415		Enable support for fpga loadbp command - load partial bitstream
2416		(Xilinx only)
2417
2418		CONFIG_SYS_FPGA_PROG_FEEDBACK
2419
2420		Enable printing of hash marks during FPGA configuration.
2421
2422		CONFIG_SYS_FPGA_CHECK_BUSY
2423
2424		Enable checks on FPGA configuration interface busy
2425		status by the configuration function. This option
2426		will require a board or device specific function to
2427		be written.
2428
2429		CONFIG_FPGA_DELAY
2430
2431		If defined, a function that provides delays in the FPGA
2432		configuration driver.
2433
2434		CONFIG_SYS_FPGA_CHECK_CTRLC
2435		Allow Control-C to interrupt FPGA configuration
2436
2437		CONFIG_SYS_FPGA_CHECK_ERROR
2438
2439		Check for configuration errors during FPGA bitfile
2440		loading. For example, abort during Virtex II
2441		configuration if the INIT_B line goes low (which
2442		indicated a CRC error).
2443
2444		CONFIG_SYS_FPGA_WAIT_INIT
2445
2446		Maximum time to wait for the INIT_B line to de-assert
2447		after PROB_B has been de-asserted during a Virtex II
2448		FPGA configuration sequence. The default time is 500
2449		ms.
2450
2451		CONFIG_SYS_FPGA_WAIT_BUSY
2452
2453		Maximum time to wait for BUSY to de-assert during
2454		Virtex II FPGA configuration. The default is 5 ms.
2455
2456		CONFIG_SYS_FPGA_WAIT_CONFIG
2457
2458		Time to wait after FPGA configuration. The default is
2459		200 ms.
2460
2461- Configuration Management:
2462		CONFIG_BUILD_TARGET
2463
2464		Some SoCs need special image types (e.g. U-Boot binary
2465		with a special header) as build targets. By defining
2466		CONFIG_BUILD_TARGET in the SoC / board header, this
2467		special image will be automatically built upon calling
2468		make / buildman.
2469
2470		CONFIG_IDENT_STRING
2471
2472		If defined, this string will be added to the U-Boot
2473		version information (U_BOOT_VERSION)
2474
2475- Vendor Parameter Protection:
2476
2477		U-Boot considers the values of the environment
2478		variables "serial#" (Board Serial Number) and
2479		"ethaddr" (Ethernet Address) to be parameters that
2480		are set once by the board vendor / manufacturer, and
2481		protects these variables from casual modification by
2482		the user. Once set, these variables are read-only,
2483		and write or delete attempts are rejected. You can
2484		change this behaviour:
2485
2486		If CONFIG_ENV_OVERWRITE is #defined in your config
2487		file, the write protection for vendor parameters is
2488		completely disabled. Anybody can change or delete
2489		these parameters.
2490
2491		Alternatively, if you define _both_ an ethaddr in the
2492		default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2493		Ethernet address is installed in the environment,
2494		which can be changed exactly ONCE by the user. [The
2495		serial# is unaffected by this, i. e. it remains
2496		read-only.]
2497
2498		The same can be accomplished in a more flexible way
2499		for any variable by configuring the type of access
2500		to allow for those variables in the ".flags" variable
2501		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2502
2503- Protected RAM:
2504		CONFIG_PRAM
2505
2506		Define this variable to enable the reservation of
2507		"protected RAM", i. e. RAM which is not overwritten
2508		by U-Boot. Define CONFIG_PRAM to hold the number of
2509		kB you want to reserve for pRAM. You can overwrite
2510		this default value by defining an environment
2511		variable "pram" to the number of kB you want to
2512		reserve. Note that the board info structure will
2513		still show the full amount of RAM. If pRAM is
2514		reserved, a new environment variable "mem" will
2515		automatically be defined to hold the amount of
2516		remaining RAM in a form that can be passed as boot
2517		argument to Linux, for instance like that:
2518
2519			setenv bootargs ... mem=\${mem}
2520			saveenv
2521
2522		This way you can tell Linux not to use this memory,
2523		either, which results in a memory region that will
2524		not be affected by reboots.
2525
2526		*WARNING* If your board configuration uses automatic
2527		detection of the RAM size, you must make sure that
2528		this memory test is non-destructive. So far, the
2529		following board configurations are known to be
2530		"pRAM-clean":
2531
2532			IVMS8, IVML24, SPD8xx, TQM8xxL,
2533			HERMES, IP860, RPXlite, LWMON,
2534			FLAGADM, TQM8260
2535
2536- Access to physical memory region (> 4GB)
2537		Some basic support is provided for operations on memory not
2538		normally accessible to U-Boot - e.g. some architectures
2539		support access to more than 4GB of memory on 32-bit
2540		machines using physical address extension or similar.
2541		Define CONFIG_PHYSMEM to access this basic support, which
2542		currently only supports clearing the memory.
2543
2544- Error Recovery:
2545		CONFIG_PANIC_HANG
2546
2547		Define this variable to stop the system in case of a
2548		fatal error, so that you have to reset it manually.
2549		This is probably NOT a good idea for an embedded
2550		system where you want the system to reboot
2551		automatically as fast as possible, but it may be
2552		useful during development since you can try to debug
2553		the conditions that lead to the situation.
2554
2555		CONFIG_NET_RETRY_COUNT
2556
2557		This variable defines the number of retries for
2558		network operations like ARP, RARP, TFTP, or BOOTP
2559		before giving up the operation. If not defined, a
2560		default value of 5 is used.
2561
2562		CONFIG_ARP_TIMEOUT
2563
2564		Timeout waiting for an ARP reply in milliseconds.
2565
2566		CONFIG_NFS_TIMEOUT
2567
2568		Timeout in milliseconds used in NFS protocol.
2569		If you encounter "ERROR: Cannot umount" in nfs command,
2570		try longer timeout such as
2571		#define CONFIG_NFS_TIMEOUT 10000UL
2572
2573- Command Interpreter:
2574		CONFIG_AUTO_COMPLETE
2575
2576		Enable auto completion of commands using TAB.
2577
2578		CONFIG_SYS_PROMPT_HUSH_PS2
2579
2580		This defines the secondary prompt string, which is
2581		printed when the command interpreter needs more input
2582		to complete a command. Usually "> ".
2583
2584	Note:
2585
2586		In the current implementation, the local variables
2587		space and global environment variables space are
2588		separated. Local variables are those you define by
2589		simply typing `name=value'. To access a local
2590		variable later on, you have write `$name' or
2591		`${name}'; to execute the contents of a variable
2592		directly type `$name' at the command prompt.
2593
2594		Global environment variables are those you use
2595		setenv/printenv to work with. To run a command stored
2596		in such a variable, you need to use the run command,
2597		and you must not use the '$' sign to access them.
2598
2599		To store commands and special characters in a
2600		variable, please use double quotation marks
2601		surrounding the whole text of the variable, instead
2602		of the backslashes before semicolons and special
2603		symbols.
2604
2605- Command Line Editing and History:
2606		CONFIG_CMDLINE_EDITING
2607
2608		Enable editing and History functions for interactive
2609		command line input operations
2610
2611- Command Line PS1/PS2 support:
2612		CONFIG_CMDLINE_PS_SUPPORT
2613
2614		Enable support for changing the command prompt string
2615		at run-time. Only static string is supported so far.
2616		The string is obtained from environment variables PS1
2617		and PS2.
2618
2619- Default Environment:
2620		CONFIG_EXTRA_ENV_SETTINGS
2621
2622		Define this to contain any number of null terminated
2623		strings (variable = value pairs) that will be part of
2624		the default environment compiled into the boot image.
2625
2626		For example, place something like this in your
2627		board's config file:
2628
2629		#define CONFIG_EXTRA_ENV_SETTINGS \
2630			"myvar1=value1\0" \
2631			"myvar2=value2\0"
2632
2633		Warning: This method is based on knowledge about the
2634		internal format how the environment is stored by the
2635		U-Boot code. This is NOT an official, exported
2636		interface! Although it is unlikely that this format
2637		will change soon, there is no guarantee either.
2638		You better know what you are doing here.
2639
2640		Note: overly (ab)use of the default environment is
2641		discouraged. Make sure to check other ways to preset
2642		the environment like the "source" command or the
2643		boot command first.
2644
2645		CONFIG_ENV_VARS_UBOOT_CONFIG
2646
2647		Define this in order to add variables describing the
2648		U-Boot build configuration to the default environment.
2649		These will be named arch, cpu, board, vendor, and soc.
2650
2651		Enabling this option will cause the following to be defined:
2652
2653		- CONFIG_SYS_ARCH
2654		- CONFIG_SYS_CPU
2655		- CONFIG_SYS_BOARD
2656		- CONFIG_SYS_VENDOR
2657		- CONFIG_SYS_SOC
2658
2659		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2660
2661		Define this in order to add variables describing certain
2662		run-time determined information about the hardware to the
2663		environment.  These will be named board_name, board_rev.
2664
2665		CONFIG_DELAY_ENVIRONMENT
2666
2667		Normally the environment is loaded when the board is
2668		initialised so that it is available to U-Boot. This inhibits
2669		that so that the environment is not available until
2670		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2671		this is instead controlled by the value of
2672		/config/load-environment.
2673
2674- DataFlash Support:
2675		CONFIG_HAS_DATAFLASH
2676
2677		Defining this option enables DataFlash features and
2678		allows to read/write in Dataflash via the standard
2679		commands cp, md...
2680
2681- Serial Flash support
2682		CONFIG_CMD_SF
2683
2684		Defining this option enables SPI flash commands
2685		'sf probe/read/write/erase/update'.
2686
2687		Usage requires an initial 'probe' to define the serial
2688		flash parameters, followed by read/write/erase/update
2689		commands.
2690
2691		The following defaults may be provided by the platform
2692		to handle the common case when only a single serial
2693		flash is present on the system.
2694
2695		CONFIG_SF_DEFAULT_BUS		Bus identifier
2696		CONFIG_SF_DEFAULT_CS		Chip-select
2697		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2698		CONFIG_SF_DEFAULT_SPEED		in Hz
2699
2700		CONFIG_CMD_SF_TEST
2701
2702		Define this option to include a destructive SPI flash
2703		test ('sf test').
2704
2705		CONFIG_SF_DUAL_FLASH		Dual flash memories
2706
2707		Define this option to use dual flash support where two flash
2708		memories can be connected with a given cs line.
2709		Currently Xilinx Zynq qspi supports these type of connections.
2710
2711- SystemACE Support:
2712		CONFIG_SYSTEMACE
2713
2714		Adding this option adds support for Xilinx SystemACE
2715		chips attached via some sort of local bus. The address
2716		of the chip must also be defined in the
2717		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2718
2719		#define CONFIG_SYSTEMACE
2720		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2721
2722		When SystemACE support is added, the "ace" device type
2723		becomes available to the fat commands, i.e. fatls.
2724
2725- TFTP Fixed UDP Port:
2726		CONFIG_TFTP_PORT
2727
2728		If this is defined, the environment variable tftpsrcp
2729		is used to supply the TFTP UDP source port value.
2730		If tftpsrcp isn't defined, the normal pseudo-random port
2731		number generator is used.
2732
2733		Also, the environment variable tftpdstp is used to supply
2734		the TFTP UDP destination port value.  If tftpdstp isn't
2735		defined, the normal port 69 is used.
2736
2737		The purpose for tftpsrcp is to allow a TFTP server to
2738		blindly start the TFTP transfer using the pre-configured
2739		target IP address and UDP port. This has the effect of
2740		"punching through" the (Windows XP) firewall, allowing
2741		the remainder of the TFTP transfer to proceed normally.
2742		A better solution is to properly configure the firewall,
2743		but sometimes that is not allowed.
2744
2745- Hashing support:
2746		CONFIG_CMD_HASH
2747
2748		This enables a generic 'hash' command which can produce
2749		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
2750
2751		CONFIG_HASH_VERIFY
2752
2753		Enable the hash verify command (hash -v). This adds to code
2754		size a little.
2755
2756		Note: There is also a sha1sum command, which should perhaps
2757		be deprecated in favour of 'hash sha1'.
2758
2759- Freescale i.MX specific commands:
2760		CONFIG_CMD_HDMIDETECT
2761		This enables 'hdmidet' command which returns true if an
2762		HDMI monitor is detected.  This command is i.MX 6 specific.
2763
2764- bootcount support:
2765		CONFIG_BOOTCOUNT_LIMIT
2766
2767		This enables the bootcounter support, see:
2768		http://www.denx.de/wiki/DULG/UBootBootCountLimit
2769
2770		CONFIG_AT91SAM9XE
2771		enable special bootcounter support on at91sam9xe based boards.
2772		CONFIG_SOC_DA8XX
2773		enable special bootcounter support on da850 based boards.
2774		CONFIG_BOOTCOUNT_RAM
2775		enable support for the bootcounter in RAM
2776		CONFIG_BOOTCOUNT_I2C
2777		enable support for the bootcounter on an i2c (like RTC) device.
2778			CONFIG_SYS_I2C_RTC_ADDR = i2c chip address
2779			CONFIG_SYS_BOOTCOUNT_ADDR = i2c addr which is used for
2780						    the bootcounter.
2781			CONFIG_BOOTCOUNT_ALEN = address len
2782
2783- Show boot progress:
2784		CONFIG_SHOW_BOOT_PROGRESS
2785
2786		Defining this option allows to add some board-
2787		specific code (calling a user-provided function
2788		"show_boot_progress(int)") that enables you to show
2789		the system's boot progress on some display (for
2790		example, some LED's) on your board. At the moment,
2791		the following checkpoints are implemented:
2792
2793
2794Legacy uImage format:
2795
2796  Arg	Where			When
2797    1	common/cmd_bootm.c	before attempting to boot an image
2798   -1	common/cmd_bootm.c	Image header has bad	 magic number
2799    2	common/cmd_bootm.c	Image header has correct magic number
2800   -2	common/cmd_bootm.c	Image header has bad	 checksum
2801    3	common/cmd_bootm.c	Image header has correct checksum
2802   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2803    4	common/cmd_bootm.c	Image data   has correct checksum
2804   -4	common/cmd_bootm.c	Image is for unsupported architecture
2805    5	common/cmd_bootm.c	Architecture check OK
2806   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2807    6	common/cmd_bootm.c	Image Type check OK
2808   -6	common/cmd_bootm.c	gunzip uncompression error
2809   -7	common/cmd_bootm.c	Unimplemented compression type
2810    7	common/cmd_bootm.c	Uncompression OK
2811    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2812   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2813
2814    9	common/image.c		Start initial ramdisk verification
2815  -10	common/image.c		Ramdisk header has bad	   magic number
2816  -11	common/image.c		Ramdisk header has bad	   checksum
2817   10	common/image.c		Ramdisk header is OK
2818  -12	common/image.c		Ramdisk data   has bad	   checksum
2819   11	common/image.c		Ramdisk data   has correct checksum
2820   12	common/image.c		Ramdisk verification complete, start loading
2821  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2822   13	common/image.c		Start multifile image verification
2823   14	common/image.c		No initial ramdisk, no multifile, continue.
2824
2825   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2826
2827  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2828  -31	post/post.c		POST test failed, detected by post_output_backlog()
2829  -32	post/post.c		POST test failed, detected by post_run_single()
2830
2831   34	common/cmd_doc.c	before loading a Image from a DOC device
2832  -35	common/cmd_doc.c	Bad usage of "doc" command
2833   35	common/cmd_doc.c	correct usage of "doc" command
2834  -36	common/cmd_doc.c	No boot device
2835   36	common/cmd_doc.c	correct boot device
2836  -37	common/cmd_doc.c	Unknown Chip ID on boot device
2837   37	common/cmd_doc.c	correct chip ID found, device available
2838  -38	common/cmd_doc.c	Read Error on boot device
2839   38	common/cmd_doc.c	reading Image header from DOC device OK
2840  -39	common/cmd_doc.c	Image header has bad magic number
2841   39	common/cmd_doc.c	Image header has correct magic number
2842  -40	common/cmd_doc.c	Error reading Image from DOC device
2843   40	common/cmd_doc.c	Image header has correct magic number
2844   41	common/cmd_ide.c	before loading a Image from a IDE device
2845  -42	common/cmd_ide.c	Bad usage of "ide" command
2846   42	common/cmd_ide.c	correct usage of "ide" command
2847  -43	common/cmd_ide.c	No boot device
2848   43	common/cmd_ide.c	boot device found
2849  -44	common/cmd_ide.c	Device not available
2850   44	common/cmd_ide.c	Device available
2851  -45	common/cmd_ide.c	wrong partition selected
2852   45	common/cmd_ide.c	partition selected
2853  -46	common/cmd_ide.c	Unknown partition table
2854   46	common/cmd_ide.c	valid partition table found
2855  -47	common/cmd_ide.c	Invalid partition type
2856   47	common/cmd_ide.c	correct partition type
2857  -48	common/cmd_ide.c	Error reading Image Header on boot device
2858   48	common/cmd_ide.c	reading Image Header from IDE device OK
2859  -49	common/cmd_ide.c	Image header has bad magic number
2860   49	common/cmd_ide.c	Image header has correct magic number
2861  -50	common/cmd_ide.c	Image header has bad	 checksum
2862   50	common/cmd_ide.c	Image header has correct checksum
2863  -51	common/cmd_ide.c	Error reading Image from IDE device
2864   51	common/cmd_ide.c	reading Image from IDE device OK
2865   52	common/cmd_nand.c	before loading a Image from a NAND device
2866  -53	common/cmd_nand.c	Bad usage of "nand" command
2867   53	common/cmd_nand.c	correct usage of "nand" command
2868  -54	common/cmd_nand.c	No boot device
2869   54	common/cmd_nand.c	boot device found
2870  -55	common/cmd_nand.c	Unknown Chip ID on boot device
2871   55	common/cmd_nand.c	correct chip ID found, device available
2872  -56	common/cmd_nand.c	Error reading Image Header on boot device
2873   56	common/cmd_nand.c	reading Image Header from NAND device OK
2874  -57	common/cmd_nand.c	Image header has bad magic number
2875   57	common/cmd_nand.c	Image header has correct magic number
2876  -58	common/cmd_nand.c	Error reading Image from NAND device
2877   58	common/cmd_nand.c	reading Image from NAND device OK
2878
2879  -60	common/env_common.c	Environment has a bad CRC, using default
2880
2881   64	net/eth.c		starting with Ethernet configuration.
2882  -64	net/eth.c		no Ethernet found.
2883   65	net/eth.c		Ethernet found.
2884
2885  -80	common/cmd_net.c	usage wrong
2886   80	common/cmd_net.c	before calling net_loop()
2887  -81	common/cmd_net.c	some error in net_loop() occurred
2888   81	common/cmd_net.c	net_loop() back without error
2889  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
2890   82	common/cmd_net.c	trying automatic boot
2891   83	common/cmd_net.c	running "source" command
2892  -83	common/cmd_net.c	some error in automatic boot or "source" command
2893   84	common/cmd_net.c	end without errors
2894
2895FIT uImage format:
2896
2897  Arg	Where			When
2898  100	common/cmd_bootm.c	Kernel FIT Image has correct format
2899 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
2900  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
2901 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
2902  102	common/cmd_bootm.c	Kernel unit name specified
2903 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
2904  103	common/cmd_bootm.c	Found configuration node
2905  104	common/cmd_bootm.c	Got kernel subimage node offset
2906 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
2907  105	common/cmd_bootm.c	Kernel subimage hash verification OK
2908 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
2909  106	common/cmd_bootm.c	Architecture check OK
2910 -106	common/cmd_bootm.c	Kernel subimage has wrong type
2911  107	common/cmd_bootm.c	Kernel subimage type OK
2912 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
2913  108	common/cmd_bootm.c	Got kernel subimage data/size
2914 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
2915 -109	common/cmd_bootm.c	Can't get kernel subimage type
2916 -110	common/cmd_bootm.c	Can't get kernel subimage comp
2917 -111	common/cmd_bootm.c	Can't get kernel subimage os
2918 -112	common/cmd_bootm.c	Can't get kernel subimage load address
2919 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
2920
2921  120	common/image.c		Start initial ramdisk verification
2922 -120	common/image.c		Ramdisk FIT image has incorrect format
2923  121	common/image.c		Ramdisk FIT image has correct format
2924  122	common/image.c		No ramdisk subimage unit name, using configuration
2925 -122	common/image.c		Can't get configuration for ramdisk subimage
2926  123	common/image.c		Ramdisk unit name specified
2927 -124	common/image.c		Can't get ramdisk subimage node offset
2928  125	common/image.c		Got ramdisk subimage node offset
2929 -125	common/image.c		Ramdisk subimage hash verification failed
2930  126	common/image.c		Ramdisk subimage hash verification OK
2931 -126	common/image.c		Ramdisk subimage for unsupported architecture
2932  127	common/image.c		Architecture check OK
2933 -127	common/image.c		Can't get ramdisk subimage data/size
2934  128	common/image.c		Got ramdisk subimage data/size
2935  129	common/image.c		Can't get ramdisk load address
2936 -129	common/image.c		Got ramdisk load address
2937
2938 -130	common/cmd_doc.c	Incorrect FIT image format
2939  131	common/cmd_doc.c	FIT image format OK
2940
2941 -140	common/cmd_ide.c	Incorrect FIT image format
2942  141	common/cmd_ide.c	FIT image format OK
2943
2944 -150	common/cmd_nand.c	Incorrect FIT image format
2945  151	common/cmd_nand.c	FIT image format OK
2946
2947- legacy image format:
2948		CONFIG_IMAGE_FORMAT_LEGACY
2949		enables the legacy image format support in U-Boot.
2950
2951		Default:
2952		enabled if CONFIG_FIT_SIGNATURE is not defined.
2953
2954		CONFIG_DISABLE_IMAGE_LEGACY
2955		disable the legacy image format
2956
2957		This define is introduced, as the legacy image format is
2958		enabled per default for backward compatibility.
2959
2960- Standalone program support:
2961		CONFIG_STANDALONE_LOAD_ADDR
2962
2963		This option defines a board specific value for the
2964		address where standalone program gets loaded, thus
2965		overwriting the architecture dependent default
2966		settings.
2967
2968- Frame Buffer Address:
2969		CONFIG_FB_ADDR
2970
2971		Define CONFIG_FB_ADDR if you want to use specific
2972		address for frame buffer.  This is typically the case
2973		when using a graphics controller has separate video
2974		memory.  U-Boot will then place the frame buffer at
2975		the given address instead of dynamically reserving it
2976		in system RAM by calling lcd_setmem(), which grabs
2977		the memory for the frame buffer depending on the
2978		configured panel size.
2979
2980		Please see board_init_f function.
2981
2982- Automatic software updates via TFTP server
2983		CONFIG_UPDATE_TFTP
2984		CONFIG_UPDATE_TFTP_CNT_MAX
2985		CONFIG_UPDATE_TFTP_MSEC_MAX
2986
2987		These options enable and control the auto-update feature;
2988		for a more detailed description refer to doc/README.update.
2989
2990- MTD Support (mtdparts command, UBI support)
2991		CONFIG_MTD_DEVICE
2992
2993		Adds the MTD device infrastructure from the Linux kernel.
2994		Needed for mtdparts command support.
2995
2996		CONFIG_MTD_PARTITIONS
2997
2998		Adds the MTD partitioning infrastructure from the Linux
2999		kernel. Needed for UBI support.
3000
3001- UBI support
3002		CONFIG_CMD_UBI
3003
3004		Adds commands for interacting with MTD partitions formatted
3005		with the UBI flash translation layer
3006
3007		Requires also defining CONFIG_RBTREE
3008
3009		CONFIG_UBI_SILENCE_MSG
3010
3011		Make the verbose messages from UBI stop printing.  This leaves
3012		warnings and errors enabled.
3013
3014
3015		CONFIG_MTD_UBI_WL_THRESHOLD
3016		This parameter defines the maximum difference between the highest
3017		erase counter value and the lowest erase counter value of eraseblocks
3018		of UBI devices. When this threshold is exceeded, UBI starts performing
3019		wear leveling by means of moving data from eraseblock with low erase
3020		counter to eraseblocks with high erase counter.
3021
3022		The default value should be OK for SLC NAND flashes, NOR flashes and
3023		other flashes which have eraseblock life-cycle 100000 or more.
3024		However, in case of MLC NAND flashes which typically have eraseblock
3025		life-cycle less than 10000, the threshold should be lessened (e.g.,
3026		to 128 or 256, although it does not have to be power of 2).
3027
3028		default: 4096
3029
3030		CONFIG_MTD_UBI_BEB_LIMIT
3031		This option specifies the maximum bad physical eraseblocks UBI
3032		expects on the MTD device (per 1024 eraseblocks). If the
3033		underlying flash does not admit of bad eraseblocks (e.g. NOR
3034		flash), this value is ignored.
3035
3036		NAND datasheets often specify the minimum and maximum NVM
3037		(Number of Valid Blocks) for the flashes' endurance lifetime.
3038		The maximum expected bad eraseblocks per 1024 eraseblocks
3039		then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
3040		which gives 20 for most NANDs (MaxNVB is basically the total
3041		count of eraseblocks on the chip).
3042
3043		To put it differently, if this value is 20, UBI will try to
3044		reserve about 1.9% of physical eraseblocks for bad blocks
3045		handling. And that will be 1.9% of eraseblocks on the entire
3046		NAND chip, not just the MTD partition UBI attaches. This means
3047		that if you have, say, a NAND flash chip admits maximum 40 bad
3048		eraseblocks, and it is split on two MTD partitions of the same
3049		size, UBI will reserve 40 eraseblocks when attaching a
3050		partition.
3051
3052		default: 20
3053
3054		CONFIG_MTD_UBI_FASTMAP
3055		Fastmap is a mechanism which allows attaching an UBI device
3056		in nearly constant time. Instead of scanning the whole MTD device it
3057		only has to locate a checkpoint (called fastmap) on the device.
3058		The on-flash fastmap contains all information needed to attach
3059		the device. Using fastmap makes only sense on large devices where
3060		attaching by scanning takes long. UBI will not automatically install
3061		a fastmap on old images, but you can set the UBI parameter
3062		CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
3063		that fastmap-enabled images are still usable with UBI implementations
3064		without	fastmap support. On typical flash devices the whole fastmap
3065		fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
3066
3067		CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
3068		Set this parameter to enable fastmap automatically on images
3069		without a fastmap.
3070		default: 0
3071
3072		CONFIG_MTD_UBI_FM_DEBUG
3073		Enable UBI fastmap debug
3074		default: 0
3075
3076- UBIFS support
3077		CONFIG_CMD_UBIFS
3078
3079		Adds commands for interacting with UBI volumes formatted as
3080		UBIFS.  UBIFS is read-only in u-boot.
3081
3082		Requires UBI support as well as CONFIG_LZO
3083
3084		CONFIG_UBIFS_SILENCE_MSG
3085
3086		Make the verbose messages from UBIFS stop printing.  This leaves
3087		warnings and errors enabled.
3088
3089- SPL framework
3090		CONFIG_SPL
3091		Enable building of SPL globally.
3092
3093		CONFIG_SPL_LDSCRIPT
3094		LDSCRIPT for linking the SPL binary.
3095
3096		CONFIG_SPL_MAX_FOOTPRINT
3097		Maximum size in memory allocated to the SPL, BSS included.
3098		When defined, the linker checks that the actual memory
3099		used by SPL from _start to __bss_end does not exceed it.
3100		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3101		must not be both defined at the same time.
3102
3103		CONFIG_SPL_MAX_SIZE
3104		Maximum size of the SPL image (text, data, rodata, and
3105		linker lists sections), BSS excluded.
3106		When defined, the linker checks that the actual size does
3107		not exceed it.
3108
3109		CONFIG_SPL_TEXT_BASE
3110		TEXT_BASE for linking the SPL binary.
3111
3112		CONFIG_SPL_RELOC_TEXT_BASE
3113		Address to relocate to.  If unspecified, this is equal to
3114		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3115
3116		CONFIG_SPL_BSS_START_ADDR
3117		Link address for the BSS within the SPL binary.
3118
3119		CONFIG_SPL_BSS_MAX_SIZE
3120		Maximum size in memory allocated to the SPL BSS.
3121		When defined, the linker checks that the actual memory used
3122		by SPL from __bss_start to __bss_end does not exceed it.
3123		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3124		must not be both defined at the same time.
3125
3126		CONFIG_SPL_STACK
3127		Adress of the start of the stack SPL will use
3128
3129		CONFIG_SPL_PANIC_ON_RAW_IMAGE
3130		When defined, SPL will panic() if the image it has
3131		loaded does not have a signature.
3132		Defining this is useful when code which loads images
3133		in SPL cannot guarantee that absolutely all read errors
3134		will be caught.
3135		An example is the LPC32XX MLC NAND driver, which will
3136		consider that a completely unreadable NAND block is bad,
3137		and thus should be skipped silently.
3138
3139		CONFIG_SPL_RELOC_STACK
3140		Adress of the start of the stack SPL will use after
3141		relocation.  If unspecified, this is equal to
3142		CONFIG_SPL_STACK.
3143
3144		CONFIG_SYS_SPL_MALLOC_START
3145		Starting address of the malloc pool used in SPL.
3146		When this option is set the full malloc is used in SPL and
3147		it is set up by spl_init() and before that, the simple malloc()
3148		can be used if CONFIG_SYS_MALLOC_F is defined.
3149
3150		CONFIG_SYS_SPL_MALLOC_SIZE
3151		The size of the malloc pool used in SPL.
3152
3153		CONFIG_SPL_FRAMEWORK
3154		Enable the SPL framework under common/.  This framework
3155		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3156		NAND loading of the Linux Kernel.
3157
3158		CONFIG_SPL_OS_BOOT
3159		Enable booting directly to an OS from SPL.
3160		See also: doc/README.falcon
3161
3162		CONFIG_SPL_DISPLAY_PRINT
3163		For ARM, enable an optional function to print more information
3164		about the running system.
3165
3166		CONFIG_SPL_INIT_MINIMAL
3167		Arch init code should be built for a very small image
3168
3169		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
3170		Partition on the MMC to load U-Boot from when the MMC is being
3171		used in raw mode
3172
3173		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3174		Sector to load kernel uImage from when MMC is being
3175		used in raw mode (for Falcon mode)
3176
3177		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3178		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3179		Sector and number of sectors to load kernel argument
3180		parameters from when MMC is being used in raw mode
3181		(for falcon mode)
3182
3183		CONFIG_SYS_MMCSD_FS_BOOT_PARTITION
3184		Partition on the MMC to load U-Boot from when the MMC is being
3185		used in fs mode
3186
3187		CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
3188		Filename to read to load U-Boot when reading from filesystem
3189
3190		CONFIG_SPL_FS_LOAD_KERNEL_NAME
3191		Filename to read to load kernel uImage when reading
3192		from filesystem (for Falcon mode)
3193
3194		CONFIG_SPL_FS_LOAD_ARGS_NAME
3195		Filename to read to load kernel argument parameters
3196		when reading from filesystem (for Falcon mode)
3197
3198		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3199		Set this for NAND SPL on PPC mpc83xx targets, so that
3200		start.S waits for the rest of the SPL to load before
3201		continuing (the hardware starts execution after just
3202		loading the first page rather than the full 4K).
3203
3204		CONFIG_SPL_SKIP_RELOCATE
3205		Avoid SPL relocation
3206
3207		CONFIG_SPL_NAND_BASE
3208		Include nand_base.c in the SPL.  Requires
3209		CONFIG_SPL_NAND_DRIVERS.
3210
3211		CONFIG_SPL_NAND_DRIVERS
3212		SPL uses normal NAND drivers, not minimal drivers.
3213
3214		CONFIG_SPL_NAND_ECC
3215		Include standard software ECC in the SPL
3216
3217		CONFIG_SPL_NAND_SIMPLE
3218		Support for NAND boot using simple NAND drivers that
3219		expose the cmd_ctrl() interface.
3220
3221		CONFIG_SPL_UBI
3222		Support for a lightweight UBI (fastmap) scanner and
3223		loader
3224
3225		CONFIG_SPL_NAND_RAW_ONLY
3226		Support to boot only raw u-boot.bin images. Use this only
3227		if you need to save space.
3228
3229		CONFIG_SPL_COMMON_INIT_DDR
3230		Set for common ddr init with serial presence detect in
3231		SPL binary.
3232
3233		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3234		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3235		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3236		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3237		CONFIG_SYS_NAND_ECCBYTES
3238		Defines the size and behavior of the NAND that SPL uses
3239		to read U-Boot
3240
3241		CONFIG_SPL_NAND_BOOT
3242		Add support NAND boot
3243
3244		CONFIG_SYS_NAND_U_BOOT_OFFS
3245		Location in NAND to read U-Boot from
3246
3247		CONFIG_SYS_NAND_U_BOOT_DST
3248		Location in memory to load U-Boot to
3249
3250		CONFIG_SYS_NAND_U_BOOT_SIZE
3251		Size of image to load
3252
3253		CONFIG_SYS_NAND_U_BOOT_START
3254		Entry point in loaded image to jump to
3255
3256		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3257		Define this if you need to first read the OOB and then the
3258		data. This is used, for example, on davinci platforms.
3259
3260		CONFIG_SPL_OMAP3_ID_NAND
3261		Support for an OMAP3-specific set of functions to return the
3262		ID and MFR of the first attached NAND chip, if present.
3263
3264		CONFIG_SPL_RAM_DEVICE
3265		Support for running image already present in ram, in SPL binary
3266
3267		CONFIG_SPL_PAD_TO
3268		Image offset to which the SPL should be padded before appending
3269		the SPL payload. By default, this is defined as
3270		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3271		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3272		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3273
3274		CONFIG_SPL_TARGET
3275		Final target image containing SPL and payload.  Some SPLs
3276		use an arch-specific makefile fragment instead, for
3277		example if more than one image needs to be produced.
3278
3279		CONFIG_FIT_SPL_PRINT
3280		Printing information about a FIT image adds quite a bit of
3281		code to SPL. So this is normally disabled in SPL. Use this
3282		option to re-enable it. This will affect the output of the
3283		bootm command when booting a FIT image.
3284
3285- TPL framework
3286		CONFIG_TPL
3287		Enable building of TPL globally.
3288
3289		CONFIG_TPL_PAD_TO
3290		Image offset to which the TPL should be padded before appending
3291		the TPL payload. By default, this is defined as
3292		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3293		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3294		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3295
3296- Interrupt support (PPC):
3297
3298		There are common interrupt_init() and timer_interrupt()
3299		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3300		for CPU specific initialization. interrupt_init_cpu()
3301		should set decrementer_count to appropriate value. If
3302		CPU resets decrementer automatically after interrupt
3303		(ppc4xx) it should set decrementer_count to zero.
3304		timer_interrupt() calls timer_interrupt_cpu() for CPU
3305		specific handling. If board has watchdog / status_led
3306		/ other_activity_monitor it works automatically from
3307		general timer_interrupt().
3308
3309
3310Board initialization settings:
3311------------------------------
3312
3313During Initialization u-boot calls a number of board specific functions
3314to allow the preparation of board specific prerequisites, e.g. pin setup
3315before drivers are initialized. To enable these callbacks the
3316following configuration macros have to be defined. Currently this is
3317architecture specific, so please check arch/your_architecture/lib/board.c
3318typically in board_init_f() and board_init_r().
3319
3320- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3321- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3322- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3323- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3324
3325Configuration Settings:
3326-----------------------
3327
3328- CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
3329		Optionally it can be defined to support 64-bit memory commands.
3330
3331- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3332		undefine this when you're short of memory.
3333
3334- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3335		width of the commands listed in the 'help' command output.
3336
3337- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3338		prompt for user input.
3339
3340- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3341
3342- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3343
3344- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3345
3346- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3347		the application (usually a Linux kernel) when it is
3348		booted
3349
3350- CONFIG_SYS_BAUDRATE_TABLE:
3351		List of legal baudrate settings for this board.
3352
3353- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3354		Begin and End addresses of the area used by the
3355		simple memory test.
3356
3357- CONFIG_SYS_ALT_MEMTEST:
3358		Enable an alternate, more extensive memory test.
3359
3360- CONFIG_SYS_MEMTEST_SCRATCH:
3361		Scratch address used by the alternate memory test
3362		You only need to set this if address zero isn't writeable
3363
3364- CONFIG_SYS_MEM_RESERVE_SECURE
3365		Only implemented for ARMv8 for now.
3366		If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
3367		is substracted from total RAM and won't be reported to OS.
3368		This memory can be used as secure memory. A variable
3369		gd->arch.secure_ram is used to track the location. In systems
3370		the RAM base is not zero, or RAM is divided into banks,
3371		this variable needs to be recalcuated to get the address.
3372
3373- CONFIG_SYS_MEM_TOP_HIDE:
3374		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3375		this specified memory area will get subtracted from the top
3376		(end) of RAM and won't get "touched" at all by U-Boot. By
3377		fixing up gd->ram_size the Linux kernel should gets passed
3378		the now "corrected" memory size and won't touch it either.
3379		This should work for arch/ppc and arch/powerpc. Only Linux
3380		board ports in arch/powerpc with bootwrapper support that
3381		recalculate the memory size from the SDRAM controller setup
3382		will have to get fixed in Linux additionally.
3383
3384		This option can be used as a workaround for the 440EPx/GRx
3385		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3386		be touched.
3387
3388		WARNING: Please make sure that this value is a multiple of
3389		the Linux page size (normally 4k). If this is not the case,
3390		then the end address of the Linux memory will be located at a
3391		non page size aligned address and this could cause major
3392		problems.
3393
3394- CONFIG_SYS_LOADS_BAUD_CHANGE:
3395		Enable temporary baudrate change while serial download
3396
3397- CONFIG_SYS_SDRAM_BASE:
3398		Physical start address of SDRAM. _Must_ be 0 here.
3399
3400- CONFIG_SYS_FLASH_BASE:
3401		Physical start address of Flash memory.
3402
3403- CONFIG_SYS_MONITOR_BASE:
3404		Physical start address of boot monitor code (set by
3405		make config files to be same as the text base address
3406		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3407		CONFIG_SYS_FLASH_BASE when booting from flash.
3408
3409- CONFIG_SYS_MONITOR_LEN:
3410		Size of memory reserved for monitor code, used to
3411		determine _at_compile_time_ (!) if the environment is
3412		embedded within the U-Boot image, or in a separate
3413		flash sector.
3414
3415- CONFIG_SYS_MALLOC_LEN:
3416		Size of DRAM reserved for malloc() use.
3417
3418- CONFIG_SYS_MALLOC_F_LEN
3419		Size of the malloc() pool for use before relocation. If
3420		this is defined, then a very simple malloc() implementation
3421		will become available before relocation. The address is just
3422		below the global data, and the stack is moved down to make
3423		space.
3424
3425		This feature allocates regions with increasing addresses
3426		within the region. calloc() is supported, but realloc()
3427		is not available. free() is supported but does nothing.
3428		The memory will be freed (or in fact just forgotten) when
3429		U-Boot relocates itself.
3430
3431- CONFIG_SYS_MALLOC_SIMPLE
3432		Provides a simple and small malloc() and calloc() for those
3433		boards which do not use the full malloc in SPL (which is
3434		enabled with CONFIG_SYS_SPL_MALLOC_START).
3435
3436- CONFIG_SYS_NONCACHED_MEMORY:
3437		Size of non-cached memory area. This area of memory will be
3438		typically located right below the malloc() area and mapped
3439		uncached in the MMU. This is useful for drivers that would
3440		otherwise require a lot of explicit cache maintenance. For
3441		some drivers it's also impossible to properly maintain the
3442		cache. For example if the regions that need to be flushed
3443		are not a multiple of the cache-line size, *and* padding
3444		cannot be allocated between the regions to align them (i.e.
3445		if the HW requires a contiguous array of regions, and the
3446		size of each region is not cache-aligned), then a flush of
3447		one region may result in overwriting data that hardware has
3448		written to another region in the same cache-line. This can
3449		happen for example in network drivers where descriptors for
3450		buffers are typically smaller than the CPU cache-line (e.g.
3451		16 bytes vs. 32 or 64 bytes).
3452
3453		Non-cached memory is only supported on 32-bit ARM at present.
3454
3455- CONFIG_SYS_BOOTM_LEN:
3456		Normally compressed uImages are limited to an
3457		uncompressed size of 8 MBytes. If this is not enough,
3458		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3459		to adjust this setting to your needs.
3460
3461- CONFIG_SYS_BOOTMAPSZ:
3462		Maximum size of memory mapped by the startup code of
3463		the Linux kernel; all data that must be processed by
3464		the Linux kernel (bd_info, boot arguments, FDT blob if
3465		used) must be put below this limit, unless "bootm_low"
3466		environment variable is defined and non-zero. In such case
3467		all data for the Linux kernel must be between "bootm_low"
3468		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3469		variable "bootm_mapsize" will override the value of
3470		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3471		then the value in "bootm_size" will be used instead.
3472
3473- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3474		Enable initrd_high functionality.  If defined then the
3475		initrd_high feature is enabled and the bootm ramdisk subcommand
3476		is enabled.
3477
3478- CONFIG_SYS_BOOT_GET_CMDLINE:
3479		Enables allocating and saving kernel cmdline in space between
3480		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3481
3482- CONFIG_SYS_BOOT_GET_KBD:
3483		Enables allocating and saving a kernel copy of the bd_info in
3484		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3485
3486- CONFIG_SYS_MAX_FLASH_BANKS:
3487		Max number of Flash memory banks
3488
3489- CONFIG_SYS_MAX_FLASH_SECT:
3490		Max number of sectors on a Flash chip
3491
3492- CONFIG_SYS_FLASH_ERASE_TOUT:
3493		Timeout for Flash erase operations (in ms)
3494
3495- CONFIG_SYS_FLASH_WRITE_TOUT:
3496		Timeout for Flash write operations (in ms)
3497
3498- CONFIG_SYS_FLASH_LOCK_TOUT
3499		Timeout for Flash set sector lock bit operation (in ms)
3500
3501- CONFIG_SYS_FLASH_UNLOCK_TOUT
3502		Timeout for Flash clear lock bits operation (in ms)
3503
3504- CONFIG_SYS_FLASH_PROTECTION
3505		If defined, hardware flash sectors protection is used
3506		instead of U-Boot software protection.
3507
3508- CONFIG_SYS_DIRECT_FLASH_TFTP:
3509
3510		Enable TFTP transfers directly to flash memory;
3511		without this option such a download has to be
3512		performed in two steps: (1) download to RAM, and (2)
3513		copy from RAM to flash.
3514
3515		The two-step approach is usually more reliable, since
3516		you can check if the download worked before you erase
3517		the flash, but in some situations (when system RAM is
3518		too limited to allow for a temporary copy of the
3519		downloaded image) this option may be very useful.
3520
3521- CONFIG_SYS_FLASH_CFI:
3522		Define if the flash driver uses extra elements in the
3523		common flash structure for storing flash geometry.
3524
3525- CONFIG_FLASH_CFI_DRIVER
3526		This option also enables the building of the cfi_flash driver
3527		in the drivers directory
3528
3529- CONFIG_FLASH_CFI_MTD
3530		This option enables the building of the cfi_mtd driver
3531		in the drivers directory. The driver exports CFI flash
3532		to the MTD layer.
3533
3534- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3535		Use buffered writes to flash.
3536
3537- CONFIG_FLASH_SPANSION_S29WS_N
3538		s29ws-n MirrorBit flash has non-standard addresses for buffered
3539		write commands.
3540
3541- CONFIG_SYS_FLASH_QUIET_TEST
3542		If this option is defined, the common CFI flash doesn't
3543		print it's warning upon not recognized FLASH banks. This
3544		is useful, if some of the configured banks are only
3545		optionally available.
3546
3547- CONFIG_FLASH_SHOW_PROGRESS
3548		If defined (must be an integer), print out countdown
3549		digits and dots.  Recommended value: 45 (9..1) for 80
3550		column displays, 15 (3..1) for 40 column displays.
3551
3552- CONFIG_FLASH_VERIFY
3553		If defined, the content of the flash (destination) is compared
3554		against the source after the write operation. An error message
3555		will be printed when the contents are not identical.
3556		Please note that this option is useless in nearly all cases,
3557		since such flash programming errors usually are detected earlier
3558		while unprotecting/erasing/programming. Please only enable
3559		this option if you really know what you are doing.
3560
3561- CONFIG_SYS_RX_ETH_BUFFER:
3562		Defines the number of Ethernet receive buffers. On some
3563		Ethernet controllers it is recommended to set this value
3564		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3565		buffers can be full shortly after enabling the interface
3566		on high Ethernet traffic.
3567		Defaults to 4 if not defined.
3568
3569- CONFIG_ENV_MAX_ENTRIES
3570
3571	Maximum number of entries in the hash table that is used
3572	internally to store the environment settings. The default
3573	setting is supposed to be generous and should work in most
3574	cases. This setting can be used to tune behaviour; see
3575	lib/hashtable.c for details.
3576
3577- CONFIG_ENV_FLAGS_LIST_DEFAULT
3578- CONFIG_ENV_FLAGS_LIST_STATIC
3579	Enable validation of the values given to environment variables when
3580	calling env set.  Variables can be restricted to only decimal,
3581	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3582	the variables can also be restricted to IP address or MAC address.
3583
3584	The format of the list is:
3585		type_attribute = [s|d|x|b|i|m]
3586		access_attribute = [a|r|o|c]
3587		attributes = type_attribute[access_attribute]
3588		entry = variable_name[:attributes]
3589		list = entry[,list]
3590
3591	The type attributes are:
3592		s - String (default)
3593		d - Decimal
3594		x - Hexadecimal
3595		b - Boolean ([1yYtT|0nNfF])
3596		i - IP address
3597		m - MAC address
3598
3599	The access attributes are:
3600		a - Any (default)
3601		r - Read-only
3602		o - Write-once
3603		c - Change-default
3604
3605	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3606		Define this to a list (string) to define the ".flags"
3607		environment variable in the default or embedded environment.
3608
3609	- CONFIG_ENV_FLAGS_LIST_STATIC
3610		Define this to a list (string) to define validation that
3611		should be done if an entry is not found in the ".flags"
3612		environment variable.  To override a setting in the static
3613		list, simply add an entry for the same variable name to the
3614		".flags" variable.
3615
3616	If CONFIG_REGEX is defined, the variable_name above is evaluated as a
3617	regular expression. This allows multiple variables to define the same
3618	flags without explicitly listing them for each variable.
3619
3620- CONFIG_ENV_ACCESS_IGNORE_FORCE
3621	If defined, don't allow the -f switch to env set override variable
3622	access flags.
3623
3624- CONFIG_USE_STDINT
3625	If stdint.h is available with your toolchain you can define this
3626	option to enable it. You can provide option 'USE_STDINT=1' when
3627	building U-Boot to enable this.
3628
3629The following definitions that deal with the placement and management
3630of environment data (variable area); in general, we support the
3631following configurations:
3632
3633- CONFIG_BUILD_ENVCRC:
3634
3635	Builds up envcrc with the target environment so that external utils
3636	may easily extract it and embed it in final U-Boot images.
3637
3638- CONFIG_ENV_IS_IN_FLASH:
3639
3640	Define this if the environment is in flash memory.
3641
3642	a) The environment occupies one whole flash sector, which is
3643	   "embedded" in the text segment with the U-Boot code. This
3644	   happens usually with "bottom boot sector" or "top boot
3645	   sector" type flash chips, which have several smaller
3646	   sectors at the start or the end. For instance, such a
3647	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3648	   such a case you would place the environment in one of the
3649	   4 kB sectors - with U-Boot code before and after it. With
3650	   "top boot sector" type flash chips, you would put the
3651	   environment in one of the last sectors, leaving a gap
3652	   between U-Boot and the environment.
3653
3654	- CONFIG_ENV_OFFSET:
3655
3656	   Offset of environment data (variable area) to the
3657	   beginning of flash memory; for instance, with bottom boot
3658	   type flash chips the second sector can be used: the offset
3659	   for this sector is given here.
3660
3661	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3662
3663	- CONFIG_ENV_ADDR:
3664
3665	   This is just another way to specify the start address of
3666	   the flash sector containing the environment (instead of
3667	   CONFIG_ENV_OFFSET).
3668
3669	- CONFIG_ENV_SECT_SIZE:
3670
3671	   Size of the sector containing the environment.
3672
3673
3674	b) Sometimes flash chips have few, equal sized, BIG sectors.
3675	   In such a case you don't want to spend a whole sector for
3676	   the environment.
3677
3678	- CONFIG_ENV_SIZE:
3679
3680	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3681	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3682	   of this flash sector for the environment. This saves
3683	   memory for the RAM copy of the environment.
3684
3685	   It may also save flash memory if you decide to use this
3686	   when your environment is "embedded" within U-Boot code,
3687	   since then the remainder of the flash sector could be used
3688	   for U-Boot code. It should be pointed out that this is
3689	   STRONGLY DISCOURAGED from a robustness point of view:
3690	   updating the environment in flash makes it always
3691	   necessary to erase the WHOLE sector. If something goes
3692	   wrong before the contents has been restored from a copy in
3693	   RAM, your target system will be dead.
3694
3695	- CONFIG_ENV_ADDR_REDUND
3696	  CONFIG_ENV_SIZE_REDUND
3697
3698	   These settings describe a second storage area used to hold
3699	   a redundant copy of the environment data, so that there is
3700	   a valid backup copy in case there is a power failure during
3701	   a "saveenv" operation.
3702
3703BE CAREFUL! Any changes to the flash layout, and some changes to the
3704source code will make it necessary to adapt <board>/u-boot.lds*
3705accordingly!
3706
3707
3708- CONFIG_ENV_IS_IN_NVRAM:
3709
3710	Define this if you have some non-volatile memory device
3711	(NVRAM, battery buffered SRAM) which you want to use for the
3712	environment.
3713
3714	- CONFIG_ENV_ADDR:
3715	- CONFIG_ENV_SIZE:
3716
3717	  These two #defines are used to determine the memory area you
3718	  want to use for environment. It is assumed that this memory
3719	  can just be read and written to, without any special
3720	  provision.
3721
3722BE CAREFUL! The first access to the environment happens quite early
3723in U-Boot initialization (when we try to get the setting of for the
3724console baudrate). You *MUST* have mapped your NVRAM area then, or
3725U-Boot will hang.
3726
3727Please note that even with NVRAM we still use a copy of the
3728environment in RAM: we could work on NVRAM directly, but we want to
3729keep settings there always unmodified except somebody uses "saveenv"
3730to save the current settings.
3731
3732
3733- CONFIG_ENV_IS_IN_EEPROM:
3734
3735	Use this if you have an EEPROM or similar serial access
3736	device and a driver for it.
3737
3738	- CONFIG_ENV_OFFSET:
3739	- CONFIG_ENV_SIZE:
3740
3741	  These two #defines specify the offset and size of the
3742	  environment area within the total memory of your EEPROM.
3743
3744	- CONFIG_SYS_I2C_EEPROM_ADDR:
3745	  If defined, specified the chip address of the EEPROM device.
3746	  The default address is zero.
3747
3748	- CONFIG_SYS_I2C_EEPROM_BUS:
3749	  If defined, specified the i2c bus of the EEPROM device.
3750
3751	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3752	  If defined, the number of bits used to address bytes in a
3753	  single page in the EEPROM device.  A 64 byte page, for example
3754	  would require six bits.
3755
3756	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3757	  If defined, the number of milliseconds to delay between
3758	  page writes.	The default is zero milliseconds.
3759
3760	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3761	  The length in bytes of the EEPROM memory array address.  Note
3762	  that this is NOT the chip address length!
3763
3764	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3765	  EEPROM chips that implement "address overflow" are ones
3766	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3767	  address and the extra bits end up in the "chip address" bit
3768	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3769	  byte chips.
3770
3771	  Note that we consider the length of the address field to
3772	  still be one byte because the extra address bits are hidden
3773	  in the chip address.
3774
3775	- CONFIG_SYS_EEPROM_SIZE:
3776	  The size in bytes of the EEPROM device.
3777
3778	- CONFIG_ENV_EEPROM_IS_ON_I2C
3779	  define this, if you have I2C and SPI activated, and your
3780	  EEPROM, which holds the environment, is on the I2C bus.
3781
3782	- CONFIG_I2C_ENV_EEPROM_BUS
3783	  if you have an Environment on an EEPROM reached over
3784	  I2C muxes, you can define here, how to reach this
3785	  EEPROM. For example:
3786
3787	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
3788
3789	  EEPROM which holds the environment, is reached over
3790	  a pca9547 i2c mux with address 0x70, channel 3.
3791
3792- CONFIG_ENV_IS_IN_DATAFLASH:
3793
3794	Define this if you have a DataFlash memory device which you
3795	want to use for the environment.
3796
3797	- CONFIG_ENV_OFFSET:
3798	- CONFIG_ENV_ADDR:
3799	- CONFIG_ENV_SIZE:
3800
3801	  These three #defines specify the offset and size of the
3802	  environment area within the total memory of your DataFlash placed
3803	  at the specified address.
3804
3805- CONFIG_ENV_IS_IN_SPI_FLASH:
3806
3807	Define this if you have a SPI Flash memory device which you
3808	want to use for the environment.
3809
3810	- CONFIG_ENV_OFFSET:
3811	- CONFIG_ENV_SIZE:
3812
3813	  These two #defines specify the offset and size of the
3814	  environment area within the SPI Flash. CONFIG_ENV_OFFSET must be
3815	  aligned to an erase sector boundary.
3816
3817	- CONFIG_ENV_SECT_SIZE:
3818
3819	  Define the SPI flash's sector size.
3820
3821	- CONFIG_ENV_OFFSET_REDUND (optional):
3822
3823	  This setting describes a second storage area of CONFIG_ENV_SIZE
3824	  size used to hold a redundant copy of the environment data, so
3825	  that there is a valid backup copy in case there is a power failure
3826	  during a "saveenv" operation. CONFIG_ENV_OFFSET_REDUND must be
3827	  aligned to an erase sector boundary.
3828
3829	- CONFIG_ENV_SPI_BUS (optional):
3830	- CONFIG_ENV_SPI_CS (optional):
3831
3832	  Define the SPI bus and chip select. If not defined they will be 0.
3833
3834	- CONFIG_ENV_SPI_MAX_HZ (optional):
3835
3836	  Define the SPI max work clock. If not defined then use 1MHz.
3837
3838	- CONFIG_ENV_SPI_MODE (optional):
3839
3840	  Define the SPI work mode. If not defined then use SPI_MODE_3.
3841
3842- CONFIG_ENV_IS_IN_REMOTE:
3843
3844	Define this if you have a remote memory space which you
3845	want to use for the local device's environment.
3846
3847	- CONFIG_ENV_ADDR:
3848	- CONFIG_ENV_SIZE:
3849
3850	  These two #defines specify the address and size of the
3851	  environment area within the remote memory space. The
3852	  local device can get the environment from remote memory
3853	  space by SRIO or PCIE links.
3854
3855BE CAREFUL! For some special cases, the local device can not use
3856"saveenv" command. For example, the local device will get the
3857environment stored in a remote NOR flash by SRIO or PCIE link,
3858but it can not erase, write this NOR flash by SRIO or PCIE interface.
3859
3860- CONFIG_ENV_IS_IN_NAND:
3861
3862	Define this if you have a NAND device which you want to use
3863	for the environment.
3864
3865	- CONFIG_ENV_OFFSET:
3866	- CONFIG_ENV_SIZE:
3867
3868	  These two #defines specify the offset and size of the environment
3869	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
3870	  aligned to an erase block boundary.
3871
3872	- CONFIG_ENV_OFFSET_REDUND (optional):
3873
3874	  This setting describes a second storage area of CONFIG_ENV_SIZE
3875	  size used to hold a redundant copy of the environment data, so
3876	  that there is a valid backup copy in case there is a power failure
3877	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_REDUND must be
3878	  aligned to an erase block boundary.
3879
3880	- CONFIG_ENV_RANGE (optional):
3881
3882	  Specifies the length of the region in which the environment
3883	  can be written.  This should be a multiple of the NAND device's
3884	  block size.  Specifying a range with more erase blocks than
3885	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
3886	  the range to be avoided.
3887
3888	- CONFIG_ENV_OFFSET_OOB (optional):
3889
3890	  Enables support for dynamically retrieving the offset of the
3891	  environment from block zero's out-of-band data.  The
3892	  "nand env.oob" command can be used to record this offset.
3893	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
3894	  using CONFIG_ENV_OFFSET_OOB.
3895
3896- CONFIG_NAND_ENV_DST
3897
3898	Defines address in RAM to which the nand_spl code should copy the
3899	environment. If redundant environment is used, it will be copied to
3900	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3901
3902- CONFIG_ENV_IS_IN_UBI:
3903
3904	Define this if you have an UBI volume that you want to use for the
3905	environment.  This has the benefit of wear-leveling the environment
3906	accesses, which is important on NAND.
3907
3908	- CONFIG_ENV_UBI_PART:
3909
3910	  Define this to a string that is the mtd partition containing the UBI.
3911
3912	- CONFIG_ENV_UBI_VOLUME:
3913
3914	  Define this to the name of the volume that you want to store the
3915	  environment in.
3916
3917	- CONFIG_ENV_UBI_VOLUME_REDUND:
3918
3919	  Define this to the name of another volume to store a second copy of
3920	  the environment in.  This will enable redundant environments in UBI.
3921	  It is assumed that both volumes are in the same MTD partition.
3922
3923	- CONFIG_UBI_SILENCE_MSG
3924	- CONFIG_UBIFS_SILENCE_MSG
3925
3926	  You will probably want to define these to avoid a really noisy system
3927	  when storing the env in UBI.
3928
3929- CONFIG_ENV_IS_IN_FAT:
3930       Define this if you want to use the FAT file system for the environment.
3931
3932       - FAT_ENV_INTERFACE:
3933
3934         Define this to a string that is the name of the block device.
3935
3936       - FAT_ENV_DEVICE_AND_PART:
3937
3938         Define this to a string to specify the partition of the device. It can
3939         be as following:
3940
3941           "D:P", "D:0", "D", "D:" or "D:auto" (D, P are integers. And P >= 1)
3942               - "D:P": device D partition P. Error occurs if device D has no
3943                        partition table.
3944               - "D:0": device D.
3945               - "D" or "D:": device D partition 1 if device D has partition
3946                              table, or the whole device D if has no partition
3947                              table.
3948               - "D:auto": first partition in device D with bootable flag set.
3949                           If none, first valid partition in device D. If no
3950                           partition table then means device D.
3951
3952       - FAT_ENV_FILE:
3953
3954         It's a string of the FAT file name. This file use to store the
3955         environment.
3956
3957       - CONFIG_FAT_WRITE:
3958         This should be defined. Otherwise it cannot save the environment file.
3959
3960- CONFIG_ENV_IS_IN_MMC:
3961
3962	Define this if you have an MMC device which you want to use for the
3963	environment.
3964
3965	- CONFIG_SYS_MMC_ENV_DEV:
3966
3967	  Specifies which MMC device the environment is stored in.
3968
3969	- CONFIG_SYS_MMC_ENV_PART (optional):
3970
3971	  Specifies which MMC partition the environment is stored in. If not
3972	  set, defaults to partition 0, the user area. Common values might be
3973	  1 (first MMC boot partition), 2 (second MMC boot partition).
3974
3975	- CONFIG_ENV_OFFSET:
3976	- CONFIG_ENV_SIZE:
3977
3978	  These two #defines specify the offset and size of the environment
3979	  area within the specified MMC device.
3980
3981	  If offset is positive (the usual case), it is treated as relative to
3982	  the start of the MMC partition. If offset is negative, it is treated
3983	  as relative to the end of the MMC partition. This can be useful if
3984	  your board may be fitted with different MMC devices, which have
3985	  different sizes for the MMC partitions, and you always want the
3986	  environment placed at the very end of the partition, to leave the
3987	  maximum possible space before it, to store other data.
3988
3989	  These two values are in units of bytes, but must be aligned to an
3990	  MMC sector boundary.
3991
3992	- CONFIG_ENV_OFFSET_REDUND (optional):
3993
3994	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
3995	  hold a redundant copy of the environment data. This provides a
3996	  valid backup copy in case the other copy is corrupted, e.g. due
3997	  to a power failure during a "saveenv" operation.
3998
3999	  This value may also be positive or negative; this is handled in the
4000	  same way as CONFIG_ENV_OFFSET.
4001
4002	  This value is also in units of bytes, but must also be aligned to
4003	  an MMC sector boundary.
4004
4005	- CONFIG_ENV_SIZE_REDUND (optional):
4006
4007	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
4008	  set. If this value is set, it must be set to the same value as
4009	  CONFIG_ENV_SIZE.
4010
4011- CONFIG_SYS_SPI_INIT_OFFSET
4012
4013	Defines offset to the initial SPI buffer area in DPRAM. The
4014	area is used at an early stage (ROM part) if the environment
4015	is configured to reside in the SPI EEPROM: We need a 520 byte
4016	scratch DPRAM area. It is used between the two initialization
4017	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
4018	to be a good choice since it makes it far enough from the
4019	start of the data area as well as from the stack pointer.
4020
4021Please note that the environment is read-only until the monitor
4022has been relocated to RAM and a RAM copy of the environment has been
4023created; also, when using EEPROM you will have to use getenv_f()
4024until then to read environment variables.
4025
4026The environment is protected by a CRC32 checksum. Before the monitor
4027is relocated into RAM, as a result of a bad CRC you will be working
4028with the compiled-in default environment - *silently*!!! [This is
4029necessary, because the first environment variable we need is the
4030"baudrate" setting for the console - if we have a bad CRC, we don't
4031have any device yet where we could complain.]
4032
4033Note: once the monitor has been relocated, then it will complain if
4034the default environment is used; a new CRC is computed as soon as you
4035use the "saveenv" command to store a valid environment.
4036
4037- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
4038		Echo the inverted Ethernet link state to the fault LED.
4039
4040		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
4041		      also needs to be defined.
4042
4043- CONFIG_SYS_FAULT_MII_ADDR:
4044		MII address of the PHY to check for the Ethernet link state.
4045
4046- CONFIG_NS16550_MIN_FUNCTIONS:
4047		Define this if you desire to only have use of the NS16550_init
4048		and NS16550_putc functions for the serial driver located at
4049		drivers/serial/ns16550.c.  This option is useful for saving
4050		space for already greatly restricted images, including but not
4051		limited to NAND_SPL configurations.
4052
4053- CONFIG_DISPLAY_BOARDINFO
4054		Display information about the board that U-Boot is running on
4055		when U-Boot starts up. The board function checkboard() is called
4056		to do this.
4057
4058- CONFIG_DISPLAY_BOARDINFO_LATE
4059		Similar to the previous option, but display this information
4060		later, once stdio is running and output goes to the LCD, if
4061		present.
4062
4063- CONFIG_BOARD_SIZE_LIMIT:
4064		Maximum size of the U-Boot image. When defined, the
4065		build system checks that the actual size does not
4066		exceed it.
4067
4068Low Level (hardware related) configuration options:
4069---------------------------------------------------
4070
4071- CONFIG_SYS_CACHELINE_SIZE:
4072		Cache Line Size of the CPU.
4073
4074- CONFIG_SYS_DEFAULT_IMMR:
4075		Default address of the IMMR after system reset.
4076
4077		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4078		and RPXsuper) to be able to adjust the position of
4079		the IMMR register after a reset.
4080
4081- CONFIG_SYS_CCSRBAR_DEFAULT:
4082		Default (power-on reset) physical address of CCSR on Freescale
4083		PowerPC SOCs.
4084
4085- CONFIG_SYS_CCSRBAR:
4086		Virtual address of CCSR.  On a 32-bit build, this is typically
4087		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4088
4089		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4090		for cross-platform code that uses that macro instead.
4091
4092- CONFIG_SYS_CCSRBAR_PHYS:
4093		Physical address of CCSR.  CCSR can be relocated to a new
4094		physical address, if desired.  In this case, this macro should
4095		be set to that address.	 Otherwise, it should be set to the
4096		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
4097		is typically relocated on 36-bit builds.  It is recommended
4098		that this macro be defined via the _HIGH and _LOW macros:
4099
4100		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4101			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4102
4103- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4104		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
4105		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
4106		used in assembly code, so it must not contain typecasts or
4107		integer size suffixes (e.g. "ULL").
4108
4109- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4110		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
4111		used in assembly code, so it must not contain typecasts or
4112		integer size suffixes (e.g. "ULL").
4113
4114- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
4115		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4116		forced to a value that ensures that CCSR is not relocated.
4117
4118- Floppy Disk Support:
4119		CONFIG_SYS_FDC_DRIVE_NUMBER
4120
4121		the default drive number (default value 0)
4122
4123		CONFIG_SYS_ISA_IO_STRIDE
4124
4125		defines the spacing between FDC chipset registers
4126		(default value 1)
4127
4128		CONFIG_SYS_ISA_IO_OFFSET
4129
4130		defines the offset of register from address. It
4131		depends on which part of the data bus is connected to
4132		the FDC chipset. (default value 0)
4133
4134		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4135		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4136		default value.
4137
4138		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4139		fdc_hw_init() is called at the beginning of the FDC
4140		setup. fdc_hw_init() must be provided by the board
4141		source code. It is used to make hardware-dependent
4142		initializations.
4143
4144- CONFIG_IDE_AHB:
4145		Most IDE controllers were designed to be connected with PCI
4146		interface. Only few of them were designed for AHB interface.
4147		When software is doing ATA command and data transfer to
4148		IDE devices through IDE-AHB controller, some additional
4149		registers accessing to these kind of IDE-AHB controller
4150		is required.
4151
4152- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4153		DO NOT CHANGE unless you know exactly what you're
4154		doing! (11-4) [MPC8xx/82xx systems only]
4155
4156- CONFIG_SYS_INIT_RAM_ADDR:
4157
4158		Start address of memory area that can be used for
4159		initial data and stack; please note that this must be
4160		writable memory that is working WITHOUT special
4161		initialization, i. e. you CANNOT use normal RAM which
4162		will become available only after programming the
4163		memory controller and running certain initialization
4164		sequences.
4165
4166		U-Boot uses the following memory types:
4167		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4168		- MPC824X: data cache
4169		- PPC4xx:  data cache
4170
4171- CONFIG_SYS_GBL_DATA_OFFSET:
4172
4173		Offset of the initial data structure in the memory
4174		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4175		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4176		data is located at the end of the available space
4177		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4178		GENERATED_GBL_DATA_SIZE), and the initial stack is just
4179		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4180		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4181
4182	Note:
4183		On the MPC824X (or other systems that use the data
4184		cache for initial memory) the address chosen for
4185		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4186		point to an otherwise UNUSED address space between
4187		the top of RAM and the start of the PCI space.
4188
4189- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4190
4191- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4192
4193- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4194
4195- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4196
4197- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4198
4199- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4200
4201- CONFIG_SYS_OR_TIMING_SDRAM:
4202		SDRAM timing
4203
4204- CONFIG_SYS_MAMR_PTA:
4205		periodic timer for refresh
4206
4207- CONFIG_SYS_DER:	Debug Event Register (37-47)
4208
4209- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4210  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4211  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4212  CONFIG_SYS_BR1_PRELIM:
4213		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4214
4215- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4216  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4217  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4218		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4219
4220- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4221  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4222		Machine Mode Register and Memory Periodic Timer
4223		Prescaler definitions (SDRAM timing)
4224
4225- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4226		enable I2C microcode relocation patch (MPC8xx);
4227		define relocation offset in DPRAM [DSP2]
4228
4229- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4230		enable SMC microcode relocation patch (MPC8xx);
4231		define relocation offset in DPRAM [SMC1]
4232
4233- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4234		enable SPI microcode relocation patch (MPC8xx);
4235		define relocation offset in DPRAM [SCC4]
4236
4237- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4238		Offset of the bootmode word in DPRAM used by post
4239		(Power On Self Tests). This definition overrides
4240		#define'd default value in commproc.h resp.
4241		cpm_8260.h.
4242
4243- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4244  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4245  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4246  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4247  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4248  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4249  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4250  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4251		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4252
4253- CONFIG_PCI_DISABLE_PCIE:
4254		Disable PCI-Express on systems where it is supported but not
4255		required.
4256
4257- CONFIG_PCI_ENUM_ONLY
4258		Only scan through and get the devices on the buses.
4259		Don't do any setup work, presumably because someone or
4260		something has already done it, and we don't need to do it
4261		a second time.	Useful for platforms that are pre-booted
4262		by coreboot or similar.
4263
4264- CONFIG_PCI_INDIRECT_BRIDGE:
4265		Enable support for indirect PCI bridges.
4266
4267- CONFIG_SYS_SRIO:
4268		Chip has SRIO or not
4269
4270- CONFIG_SRIO1:
4271		Board has SRIO 1 port available
4272
4273- CONFIG_SRIO2:
4274		Board has SRIO 2 port available
4275
4276- CONFIG_SRIO_PCIE_BOOT_MASTER
4277		Board can support master function for Boot from SRIO and PCIE
4278
4279- CONFIG_SYS_SRIOn_MEM_VIRT:
4280		Virtual Address of SRIO port 'n' memory region
4281
4282- CONFIG_SYS_SRIOn_MEM_PHYS:
4283		Physical Address of SRIO port 'n' memory region
4284
4285- CONFIG_SYS_SRIOn_MEM_SIZE:
4286		Size of SRIO port 'n' memory region
4287
4288- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4289		Defined to tell the NAND controller that the NAND chip is using
4290		a 16 bit bus.
4291		Not all NAND drivers use this symbol.
4292		Example of drivers that use it:
4293		- drivers/mtd/nand/ndfc.c
4294		- drivers/mtd/nand/mxc_nand.c
4295
4296- CONFIG_SYS_NDFC_EBC0_CFG
4297		Sets the EBC0_CFG register for the NDFC. If not defined
4298		a default value will be used.
4299
4300- CONFIG_SPD_EEPROM
4301		Get DDR timing information from an I2C EEPROM. Common
4302		with pluggable memory modules such as SODIMMs
4303
4304  SPD_EEPROM_ADDRESS
4305		I2C address of the SPD EEPROM
4306
4307- CONFIG_SYS_SPD_BUS_NUM
4308		If SPD EEPROM is on an I2C bus other than the first
4309		one, specify here. Note that the value must resolve
4310		to something your driver can deal with.
4311
4312- CONFIG_SYS_DDR_RAW_TIMING
4313		Get DDR timing information from other than SPD. Common with
4314		soldered DDR chips onboard without SPD. DDR raw timing
4315		parameters are extracted from datasheet and hard-coded into
4316		header files or board specific files.
4317
4318- CONFIG_FSL_DDR_INTERACTIVE
4319		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4320
4321- CONFIG_FSL_DDR_SYNC_REFRESH
4322		Enable sync of refresh for multiple controllers.
4323
4324- CONFIG_FSL_DDR_BIST
4325		Enable built-in memory test for Freescale DDR controllers.
4326
4327- CONFIG_SYS_83XX_DDR_USES_CS0
4328		Only for 83xx systems. If specified, then DDR should
4329		be configured using CS0 and CS1 instead of CS2 and CS3.
4330
4331- CONFIG_ETHER_ON_FEC[12]
4332		Define to enable FEC[12] on a 8xx series processor.
4333
4334- CONFIG_FEC[12]_PHY
4335		Define to the hardcoded PHY address which corresponds
4336		to the given FEC; i. e.
4337			#define CONFIG_FEC1_PHY 4
4338		means that the PHY with address 4 is connected to FEC1
4339
4340		When set to -1, means to probe for first available.
4341
4342- CONFIG_FEC[12]_PHY_NORXERR
4343		The PHY does not have a RXERR line (RMII only).
4344		(so program the FEC to ignore it).
4345
4346- CONFIG_RMII
4347		Enable RMII mode for all FECs.
4348		Note that this is a global option, we can't
4349		have one FEC in standard MII mode and another in RMII mode.
4350
4351- CONFIG_CRC32_VERIFY
4352		Add a verify option to the crc32 command.
4353		The syntax is:
4354
4355		=> crc32 -v <address> <count> <crc32>
4356
4357		Where address/count indicate a memory area
4358		and crc32 is the correct crc32 which the
4359		area should have.
4360
4361- CONFIG_LOOPW
4362		Add the "loopw" memory command. This only takes effect if
4363		the memory commands are activated globally (CONFIG_CMD_MEM).
4364
4365- CONFIG_MX_CYCLIC
4366		Add the "mdc" and "mwc" memory commands. These are cyclic
4367		"md/mw" commands.
4368		Examples:
4369
4370		=> mdc.b 10 4 500
4371		This command will print 4 bytes (10,11,12,13) each 500 ms.
4372
4373		=> mwc.l 100 12345678 10
4374		This command will write 12345678 to address 100 all 10 ms.
4375
4376		This only takes effect if the memory commands are activated
4377		globally (CONFIG_CMD_MEM).
4378
4379- CONFIG_SKIP_LOWLEVEL_INIT
4380		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4381		low level initializations (like setting up the memory
4382		controller) are omitted and/or U-Boot does not
4383		relocate itself into RAM.
4384
4385		Normally this variable MUST NOT be defined. The only
4386		exception is when U-Boot is loaded (to RAM) by some
4387		other boot loader or by a debugger which performs
4388		these initializations itself.
4389
4390- CONFIG_SKIP_LOWLEVEL_INIT_ONLY
4391		[ARM926EJ-S only] This allows just the call to lowlevel_init()
4392		to be skipped. The normal CP15 init (such as enabling the
4393		instruction cache) is still performed.
4394
4395- CONFIG_SPL_BUILD
4396		Modifies the behaviour of start.S when compiling a loader
4397		that is executed before the actual U-Boot. E.g. when
4398		compiling a NAND SPL.
4399
4400- CONFIG_TPL_BUILD
4401		Modifies the behaviour of start.S  when compiling a loader
4402		that is executed after the SPL and before the actual U-Boot.
4403		It is loaded by the SPL.
4404
4405- CONFIG_SYS_MPC85XX_NO_RESETVEC
4406		Only for 85xx systems. If this variable is specified, the section
4407		.resetvec is not kept and the section .bootpg is placed in the
4408		previous 4k of the .text section.
4409
4410- CONFIG_ARCH_MAP_SYSMEM
4411		Generally U-Boot (and in particular the md command) uses
4412		effective address. It is therefore not necessary to regard
4413		U-Boot address as virtual addresses that need to be translated
4414		to physical addresses. However, sandbox requires this, since
4415		it maintains its own little RAM buffer which contains all
4416		addressable memory. This option causes some memory accesses
4417		to be mapped through map_sysmem() / unmap_sysmem().
4418
4419- CONFIG_X86_RESET_VECTOR
4420		If defined, the x86 reset vector code is included. This is not
4421		needed when U-Boot is running from Coreboot.
4422
4423- CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
4424		Enables the RTC32K OSC on AM33xx based plattforms
4425
4426- CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
4427		Option to disable subpage write in NAND driver
4428		driver that uses this:
4429		drivers/mtd/nand/davinci_nand.c
4430
4431Freescale QE/FMAN Firmware Support:
4432-----------------------------------
4433
4434The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4435loading of "firmware", which is encoded in the QE firmware binary format.
4436This firmware often needs to be loaded during U-Boot booting, so macros
4437are used to identify the storage device (NOR flash, SPI, etc) and the address
4438within that device.
4439
4440- CONFIG_SYS_FMAN_FW_ADDR
4441	The address in the storage device where the FMAN microcode is located.  The
4442	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4443	is also specified.
4444
4445- CONFIG_SYS_QE_FW_ADDR
4446	The address in the storage device where the QE microcode is located.  The
4447	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4448	is also specified.
4449
4450- CONFIG_SYS_QE_FMAN_FW_LENGTH
4451	The maximum possible size of the firmware.  The firmware binary format
4452	has a field that specifies the actual size of the firmware, but it
4453	might not be possible to read any part of the firmware unless some
4454	local storage is allocated to hold the entire firmware first.
4455
4456- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4457	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4458	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4459	virtual address in NOR flash.
4460
4461- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4462	Specifies that QE/FMAN firmware is located in NAND flash.
4463	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4464
4465- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4466	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4467	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4468
4469- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4470	Specifies that QE/FMAN firmware is located in the remote (master)
4471	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4472	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4473	window->master inbound window->master LAW->the ucode address in
4474	master's memory space.
4475
4476Freescale Layerscape Management Complex Firmware Support:
4477---------------------------------------------------------
4478The Freescale Layerscape Management Complex (MC) supports the loading of
4479"firmware".
4480This firmware often needs to be loaded during U-Boot booting, so macros
4481are used to identify the storage device (NOR flash, SPI, etc) and the address
4482within that device.
4483
4484- CONFIG_FSL_MC_ENET
4485	Enable the MC driver for Layerscape SoCs.
4486
4487Freescale Layerscape Debug Server Support:
4488-------------------------------------------
4489The Freescale Layerscape Debug Server Support supports the loading of
4490"Debug Server firmware" and triggering SP boot-rom.
4491This firmware often needs to be loaded during U-Boot booting.
4492
4493- CONFIG_SYS_MC_RSV_MEM_ALIGN
4494	Define alignment of reserved memory MC requires
4495
4496Reproducible builds
4497-------------------
4498
4499In order to achieve reproducible builds, timestamps used in the U-Boot build
4500process have to be set to a fixed value.
4501
4502This is done using the SOURCE_DATE_EPOCH environment variable.
4503SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
4504option for U-Boot or an environment variable in U-Boot.
4505
4506SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
4507
4508Building the Software:
4509======================
4510
4511Building U-Boot has been tested in several native build environments
4512and in many different cross environments. Of course we cannot support
4513all possibly existing versions of cross development tools in all
4514(potentially obsolete) versions. In case of tool chain problems we
4515recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4516which is extensively used to build and test U-Boot.
4517
4518If you are not using a native environment, it is assumed that you
4519have GNU cross compiling tools available in your path. In this case,
4520you must set the environment variable CROSS_COMPILE in your shell.
4521Note that no changes to the Makefile or any other source files are
4522necessary. For example using the ELDK on a 4xx CPU, please enter:
4523
4524	$ CROSS_COMPILE=ppc_4xx-
4525	$ export CROSS_COMPILE
4526
4527Note: If you wish to generate Windows versions of the utilities in
4528      the tools directory you can use the MinGW toolchain
4529      (http://www.mingw.org).  Set your HOST tools to the MinGW
4530      toolchain and execute 'make tools'.  For example:
4531
4532       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4533
4534      Binaries such as tools/mkimage.exe will be created which can
4535      be executed on computers running Windows.
4536
4537U-Boot is intended to be simple to build. After installing the
4538sources you must configure U-Boot for one specific board type. This
4539is done by typing:
4540
4541	make NAME_defconfig
4542
4543where "NAME_defconfig" is the name of one of the existing configu-
4544rations; see boards.cfg for supported names.
4545
4546Note: for some board special configuration names may exist; check if
4547      additional information is available from the board vendor; for
4548      instance, the TQM823L systems are available without (standard)
4549      or with LCD support. You can select such additional "features"
4550      when choosing the configuration, i. e.
4551
4552      make TQM823L_defconfig
4553	- will configure for a plain TQM823L, i. e. no LCD support
4554
4555      make TQM823L_LCD_defconfig
4556	- will configure for a TQM823L with U-Boot console on LCD
4557
4558      etc.
4559
4560
4561Finally, type "make all", and you should get some working U-Boot
4562images ready for download to / installation on your system:
4563
4564- "u-boot.bin" is a raw binary image
4565- "u-boot" is an image in ELF binary format
4566- "u-boot.srec" is in Motorola S-Record format
4567
4568By default the build is performed locally and the objects are saved
4569in the source directory. One of the two methods can be used to change
4570this behavior and build U-Boot to some external directory:
4571
45721. Add O= to the make command line invocations:
4573
4574	make O=/tmp/build distclean
4575	make O=/tmp/build NAME_defconfig
4576	make O=/tmp/build all
4577
45782. Set environment variable KBUILD_OUTPUT to point to the desired location:
4579
4580	export KBUILD_OUTPUT=/tmp/build
4581	make distclean
4582	make NAME_defconfig
4583	make all
4584
4585Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
4586variable.
4587
4588
4589Please be aware that the Makefiles assume you are using GNU make, so
4590for instance on NetBSD you might need to use "gmake" instead of
4591native "make".
4592
4593
4594If the system board that you have is not listed, then you will need
4595to port U-Boot to your hardware platform. To do this, follow these
4596steps:
4597
45981.  Create a new directory to hold your board specific code. Add any
4599    files you need. In your board directory, you will need at least
4600    the "Makefile" and a "<board>.c".
46012.  Create a new configuration file "include/configs/<board>.h" for
4602    your board.
46033.  If you're porting U-Boot to a new CPU, then also create a new
4604    directory to hold your CPU specific code. Add any files you need.
46054.  Run "make <board>_defconfig" with your new name.
46065.  Type "make", and you should get a working "u-boot.srec" file
4607    to be installed on your target system.
46086.  Debug and solve any problems that might arise.
4609    [Of course, this last step is much harder than it sounds.]
4610
4611
4612Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4613==============================================================
4614
4615If you have modified U-Boot sources (for instance added a new board
4616or support for new devices, a new CPU, etc.) you are expected to
4617provide feedback to the other developers. The feedback normally takes
4618the form of a "patch", i. e. a context diff against a certain (latest
4619official or latest in the git repository) version of U-Boot sources.
4620
4621But before you submit such a patch, please verify that your modifi-
4622cation did not break existing code. At least make sure that *ALL* of
4623the supported boards compile WITHOUT ANY compiler warnings. To do so,
4624just run the buildman script (tools/buildman/buildman), which will
4625configure and build U-Boot for ALL supported system. Be warned, this
4626will take a while. Please see the buildman README, or run 'buildman -H'
4627for documentation.
4628
4629
4630See also "U-Boot Porting Guide" below.
4631
4632
4633Monitor Commands - Overview:
4634============================
4635
4636go	- start application at address 'addr'
4637run	- run commands in an environment variable
4638bootm	- boot application image from memory
4639bootp	- boot image via network using BootP/TFTP protocol
4640bootz   - boot zImage from memory
4641tftpboot- boot image via network using TFTP protocol
4642	       and env variables "ipaddr" and "serverip"
4643	       (and eventually "gatewayip")
4644tftpput - upload a file via network using TFTP protocol
4645rarpboot- boot image via network using RARP/TFTP protocol
4646diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4647loads	- load S-Record file over serial line
4648loadb	- load binary file over serial line (kermit mode)
4649md	- memory display
4650mm	- memory modify (auto-incrementing)
4651nm	- memory modify (constant address)
4652mw	- memory write (fill)
4653cp	- memory copy
4654cmp	- memory compare
4655crc32	- checksum calculation
4656i2c	- I2C sub-system
4657sspi	- SPI utility commands
4658base	- print or set address offset
4659printenv- print environment variables
4660setenv	- set environment variables
4661saveenv - save environment variables to persistent storage
4662protect - enable or disable FLASH write protection
4663erase	- erase FLASH memory
4664flinfo	- print FLASH memory information
4665nand	- NAND memory operations (see doc/README.nand)
4666bdinfo	- print Board Info structure
4667iminfo	- print header information for application image
4668coninfo - print console devices and informations
4669ide	- IDE sub-system
4670loop	- infinite loop on address range
4671loopw	- infinite write loop on address range
4672mtest	- simple RAM test
4673icache	- enable or disable instruction cache
4674dcache	- enable or disable data cache
4675reset	- Perform RESET of the CPU
4676echo	- echo args to console
4677version - print monitor version
4678help	- print online help
4679?	- alias for 'help'
4680
4681
4682Monitor Commands - Detailed Description:
4683========================================
4684
4685TODO.
4686
4687For now: just type "help <command>".
4688
4689
4690Environment Variables:
4691======================
4692
4693U-Boot supports user configuration using Environment Variables which
4694can be made persistent by saving to Flash memory.
4695
4696Environment Variables are set using "setenv", printed using
4697"printenv", and saved to Flash using "saveenv". Using "setenv"
4698without a value can be used to delete a variable from the
4699environment. As long as you don't save the environment you are
4700working with an in-memory copy. In case the Flash area containing the
4701environment is erased by accident, a default environment is provided.
4702
4703Some configuration options can be set using Environment Variables.
4704
4705List of environment variables (most likely not complete):
4706
4707  baudrate	- see CONFIG_BAUDRATE
4708
4709  bootdelay	- see CONFIG_BOOTDELAY
4710
4711  bootcmd	- see CONFIG_BOOTCOMMAND
4712
4713  bootargs	- Boot arguments when booting an RTOS image
4714
4715  bootfile	- Name of the image to load with TFTP
4716
4717  bootm_low	- Memory range available for image processing in the bootm
4718		  command can be restricted. This variable is given as
4719		  a hexadecimal number and defines lowest address allowed
4720		  for use by the bootm command. See also "bootm_size"
4721		  environment variable. Address defined by "bootm_low" is
4722		  also the base of the initial memory mapping for the Linux
4723		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
4724		  bootm_mapsize.
4725
4726  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
4727		  This variable is given as a hexadecimal number and it
4728		  defines the size of the memory region starting at base
4729		  address bootm_low that is accessible by the Linux kernel
4730		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
4731		  as the default value if it is defined, and bootm_size is
4732		  used otherwise.
4733
4734  bootm_size	- Memory range available for image processing in the bootm
4735		  command can be restricted. This variable is given as
4736		  a hexadecimal number and defines the size of the region
4737		  allowed for use by the bootm command. See also "bootm_low"
4738		  environment variable.
4739
4740  updatefile	- Location of the software update file on a TFTP server, used
4741		  by the automatic software update feature. Please refer to
4742		  documentation in doc/README.update for more details.
4743
4744  autoload	- if set to "no" (any string beginning with 'n'),
4745		  "bootp" will just load perform a lookup of the
4746		  configuration from the BOOTP server, but not try to
4747		  load any image using TFTP
4748
4749  autostart	- if set to "yes", an image loaded using the "bootp",
4750		  "rarpboot", "tftpboot" or "diskboot" commands will
4751		  be automatically started (by internally calling
4752		  "bootm")
4753
4754		  If set to "no", a standalone image passed to the
4755		  "bootm" command will be copied to the load address
4756		  (and eventually uncompressed), but NOT be started.
4757		  This can be used to load and uncompress arbitrary
4758		  data.
4759
4760  fdt_high	- if set this restricts the maximum address that the
4761		  flattened device tree will be copied into upon boot.
4762		  For example, if you have a system with 1 GB memory
4763		  at physical address 0x10000000, while Linux kernel
4764		  only recognizes the first 704 MB as low memory, you
4765		  may need to set fdt_high as 0x3C000000 to have the
4766		  device tree blob be copied to the maximum address
4767		  of the 704 MB low memory, so that Linux kernel can
4768		  access it during the boot procedure.
4769
4770		  If this is set to the special value 0xFFFFFFFF then
4771		  the fdt will not be copied at all on boot.  For this
4772		  to work it must reside in writable memory, have
4773		  sufficient padding on the end of it for u-boot to
4774		  add the information it needs into it, and the memory
4775		  must be accessible by the kernel.
4776
4777  fdtcontroladdr- if set this is the address of the control flattened
4778		  device tree used by U-Boot when CONFIG_OF_CONTROL is
4779		  defined.
4780
4781  i2cfast	- (PPC405GP|PPC405EP only)
4782		  if set to 'y' configures Linux I2C driver for fast
4783		  mode (400kHZ). This environment variable is used in
4784		  initialization code. So, for changes to be effective
4785		  it must be saved and board must be reset.
4786
4787  initrd_high	- restrict positioning of initrd images:
4788		  If this variable is not set, initrd images will be
4789		  copied to the highest possible address in RAM; this
4790		  is usually what you want since it allows for
4791		  maximum initrd size. If for some reason you want to
4792		  make sure that the initrd image is loaded below the
4793		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
4794		  variable to a value of "no" or "off" or "0".
4795		  Alternatively, you can set it to a maximum upper
4796		  address to use (U-Boot will still check that it
4797		  does not overwrite the U-Boot stack and data).
4798
4799		  For instance, when you have a system with 16 MB
4800		  RAM, and want to reserve 4 MB from use by Linux,
4801		  you can do this by adding "mem=12M" to the value of
4802		  the "bootargs" variable. However, now you must make
4803		  sure that the initrd image is placed in the first
4804		  12 MB as well - this can be done with
4805
4806		  setenv initrd_high 00c00000
4807
4808		  If you set initrd_high to 0xFFFFFFFF, this is an
4809		  indication to U-Boot that all addresses are legal
4810		  for the Linux kernel, including addresses in flash
4811		  memory. In this case U-Boot will NOT COPY the
4812		  ramdisk at all. This may be useful to reduce the
4813		  boot time on your system, but requires that this
4814		  feature is supported by your Linux kernel.
4815
4816  ipaddr	- IP address; needed for tftpboot command
4817
4818  loadaddr	- Default load address for commands like "bootp",
4819		  "rarpboot", "tftpboot", "loadb" or "diskboot"
4820
4821  loads_echo	- see CONFIG_LOADS_ECHO
4822
4823  serverip	- TFTP server IP address; needed for tftpboot command
4824
4825  bootretry	- see CONFIG_BOOT_RETRY_TIME
4826
4827  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
4828
4829  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
4830
4831  ethprime	- controls which interface is used first.
4832
4833  ethact	- controls which interface is currently active.
4834		  For example you can do the following
4835
4836		  => setenv ethact FEC
4837		  => ping 192.168.0.1 # traffic sent on FEC
4838		  => setenv ethact SCC
4839		  => ping 10.0.0.1 # traffic sent on SCC
4840
4841  ethrotate	- When set to "no" U-Boot does not go through all
4842		  available network interfaces.
4843		  It just stays at the currently selected interface.
4844
4845  netretry	- When set to "no" each network operation will
4846		  either succeed or fail without retrying.
4847		  When set to "once" the network operation will
4848		  fail when all the available network interfaces
4849		  are tried once without success.
4850		  Useful on scripts which control the retry operation
4851		  themselves.
4852
4853  npe_ucode	- set load address for the NPE microcode
4854
4855  silent_linux  - If set then Linux will be told to boot silently, by
4856		  changing the console to be empty. If "yes" it will be
4857		  made silent. If "no" it will not be made silent. If
4858		  unset, then it will be made silent if the U-Boot console
4859		  is silent.
4860
4861  tftpsrcp	- If this is set, the value is used for TFTP's
4862		  UDP source port.
4863
4864  tftpdstp	- If this is set, the value is used for TFTP's UDP
4865		  destination port instead of the Well Know Port 69.
4866
4867  tftpblocksize - Block size to use for TFTP transfers; if not set,
4868		  we use the TFTP server's default block size
4869
4870  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
4871		  seconds, minimum value is 1000 = 1 second). Defines
4872		  when a packet is considered to be lost so it has to
4873		  be retransmitted. The default is 5000 = 5 seconds.
4874		  Lowering this value may make downloads succeed
4875		  faster in networks with high packet loss rates or
4876		  with unreliable TFTP servers.
4877
4878  tftptimeoutcountmax	- maximum count of TFTP timeouts (no
4879		  unit, minimum value = 0). Defines how many timeouts
4880		  can happen during a single file transfer before that
4881		  transfer is aborted. The default is 10, and 0 means
4882		  'no timeouts allowed'. Increasing this value may help
4883		  downloads succeed with high packet loss rates, or with
4884		  unreliable TFTP servers or client hardware.
4885
4886  vlan		- When set to a value < 4095 the traffic over
4887		  Ethernet is encapsulated/received over 802.1q
4888		  VLAN tagged frames.
4889
4890  bootpretryperiod	- Period during which BOOTP/DHCP sends retries.
4891		  Unsigned value, in milliseconds. If not set, the period will
4892		  be either the default (28000), or a value based on
4893		  CONFIG_NET_RETRY_COUNT, if defined. This value has
4894		  precedence over the valu based on CONFIG_NET_RETRY_COUNT.
4895
4896The following image location variables contain the location of images
4897used in booting. The "Image" column gives the role of the image and is
4898not an environment variable name. The other columns are environment
4899variable names. "File Name" gives the name of the file on a TFTP
4900server, "RAM Address" gives the location in RAM the image will be
4901loaded to, and "Flash Location" gives the image's address in NOR
4902flash or offset in NAND flash.
4903
4904*Note* - these variables don't have to be defined for all boards, some
4905boards currently use other variables for these purposes, and some
4906boards use these variables for other purposes.
4907
4908Image		    File Name	     RAM Address       Flash Location
4909-----		    ---------	     -----------       --------------
4910u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
4911Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
4912device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
4913ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
4914
4915The following environment variables may be used and automatically
4916updated by the network boot commands ("bootp" and "rarpboot"),
4917depending the information provided by your boot server:
4918
4919  bootfile	- see above
4920  dnsip		- IP address of your Domain Name Server
4921  dnsip2	- IP address of your secondary Domain Name Server
4922  gatewayip	- IP address of the Gateway (Router) to use
4923  hostname	- Target hostname
4924  ipaddr	- see above
4925  netmask	- Subnet Mask
4926  rootpath	- Pathname of the root filesystem on the NFS server
4927  serverip	- see above
4928
4929
4930There are two special Environment Variables:
4931
4932  serial#	- contains hardware identification information such
4933		  as type string and/or serial number
4934  ethaddr	- Ethernet address
4935
4936These variables can be set only once (usually during manufacturing of
4937the board). U-Boot refuses to delete or overwrite these variables
4938once they have been set once.
4939
4940
4941Further special Environment Variables:
4942
4943  ver		- Contains the U-Boot version string as printed
4944		  with the "version" command. This variable is
4945		  readonly (see CONFIG_VERSION_VARIABLE).
4946
4947
4948Please note that changes to some configuration parameters may take
4949only effect after the next boot (yes, that's just like Windoze :-).
4950
4951
4952Callback functions for environment variables:
4953---------------------------------------------
4954
4955For some environment variables, the behavior of u-boot needs to change
4956when their values are changed.  This functionality allows functions to
4957be associated with arbitrary variables.  On creation, overwrite, or
4958deletion, the callback will provide the opportunity for some side
4959effect to happen or for the change to be rejected.
4960
4961The callbacks are named and associated with a function using the
4962U_BOOT_ENV_CALLBACK macro in your board or driver code.
4963
4964These callbacks are associated with variables in one of two ways.  The
4965static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
4966in the board configuration to a string that defines a list of
4967associations.  The list must be in the following format:
4968
4969	entry = variable_name[:callback_name]
4970	list = entry[,list]
4971
4972If the callback name is not specified, then the callback is deleted.
4973Spaces are also allowed anywhere in the list.
4974
4975Callbacks can also be associated by defining the ".callbacks" variable
4976with the same list format above.  Any association in ".callbacks" will
4977override any association in the static list. You can define
4978CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
4979".callbacks" environment variable in the default or embedded environment.
4980
4981If CONFIG_REGEX is defined, the variable_name above is evaluated as a
4982regular expression. This allows multiple variables to be connected to
4983the same callback without explicitly listing them all out.
4984
4985
4986Command Line Parsing:
4987=====================
4988
4989There are two different command line parsers available with U-Boot:
4990the old "simple" one, and the much more powerful "hush" shell:
4991
4992Old, simple command line parser:
4993--------------------------------
4994
4995- supports environment variables (through setenv / saveenv commands)
4996- several commands on one line, separated by ';'
4997- variable substitution using "... ${name} ..." syntax
4998- special characters ('$', ';') can be escaped by prefixing with '\',
4999  for example:
5000	setenv bootcmd bootm \${address}
5001- You can also escape text by enclosing in single apostrophes, for example:
5002	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
5003
5004Hush shell:
5005-----------
5006
5007- similar to Bourne shell, with control structures like
5008  if...then...else...fi, for...do...done; while...do...done,
5009  until...do...done, ...
5010- supports environment ("global") variables (through setenv / saveenv
5011  commands) and local shell variables (through standard shell syntax
5012  "name=value"); only environment variables can be used with "run"
5013  command
5014
5015General rules:
5016--------------
5017
5018(1) If a command line (or an environment variable executed by a "run"
5019    command) contains several commands separated by semicolon, and
5020    one of these commands fails, then the remaining commands will be
5021    executed anyway.
5022
5023(2) If you execute several variables with one call to run (i. e.
5024    calling run with a list of variables as arguments), any failing
5025    command will cause "run" to terminate, i. e. the remaining
5026    variables are not executed.
5027
5028Note for Redundant Ethernet Interfaces:
5029=======================================
5030
5031Some boards come with redundant Ethernet interfaces; U-Boot supports
5032such configurations and is capable of automatic selection of a
5033"working" interface when needed. MAC assignment works as follows:
5034
5035Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
5036MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
5037"eth1addr" (=>eth1), "eth2addr", ...
5038
5039If the network interface stores some valid MAC address (for instance
5040in SROM), this is used as default address if there is NO correspon-
5041ding setting in the environment; if the corresponding environment
5042variable is set, this overrides the settings in the card; that means:
5043
5044o If the SROM has a valid MAC address, and there is no address in the
5045  environment, the SROM's address is used.
5046
5047o If there is no valid address in the SROM, and a definition in the
5048  environment exists, then the value from the environment variable is
5049  used.
5050
5051o If both the SROM and the environment contain a MAC address, and
5052  both addresses are the same, this MAC address is used.
5053
5054o If both the SROM and the environment contain a MAC address, and the
5055  addresses differ, the value from the environment is used and a
5056  warning is printed.
5057
5058o If neither SROM nor the environment contain a MAC address, an error
5059  is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
5060  a random, locally-assigned MAC is used.
5061
5062If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
5063will be programmed into hardware as part of the initialization process.	 This
5064may be skipped by setting the appropriate 'ethmacskip' environment variable.
5065The naming convention is as follows:
5066"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
5067
5068Image Formats:
5069==============
5070
5071U-Boot is capable of booting (and performing other auxiliary operations on)
5072images in two formats:
5073
5074New uImage format (FIT)
5075-----------------------
5076
5077Flexible and powerful format based on Flattened Image Tree -- FIT (similar
5078to Flattened Device Tree). It allows the use of images with multiple
5079components (several kernels, ramdisks, etc.), with contents protected by
5080SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
5081
5082
5083Old uImage format
5084-----------------
5085
5086Old image format is based on binary files which can be basically anything,
5087preceded by a special header; see the definitions in include/image.h for
5088details; basically, the header defines the following image properties:
5089
5090* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
5091  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
5092  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
5093  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
5094  INTEGRITY).
5095* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
5096  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
5097  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
5098* Compression Type (uncompressed, gzip, bzip2)
5099* Load Address
5100* Entry Point
5101* Image Name
5102* Image Timestamp
5103
5104The header is marked by a special Magic Number, and both the header
5105and the data portions of the image are secured against corruption by
5106CRC32 checksums.
5107
5108
5109Linux Support:
5110==============
5111
5112Although U-Boot should support any OS or standalone application
5113easily, the main focus has always been on Linux during the design of
5114U-Boot.
5115
5116U-Boot includes many features that so far have been part of some
5117special "boot loader" code within the Linux kernel. Also, any
5118"initrd" images to be used are no longer part of one big Linux image;
5119instead, kernel and "initrd" are separate images. This implementation
5120serves several purposes:
5121
5122- the same features can be used for other OS or standalone
5123  applications (for instance: using compressed images to reduce the
5124  Flash memory footprint)
5125
5126- it becomes much easier to port new Linux kernel versions because
5127  lots of low-level, hardware dependent stuff are done by U-Boot
5128
5129- the same Linux kernel image can now be used with different "initrd"
5130  images; of course this also means that different kernel images can
5131  be run with the same "initrd". This makes testing easier (you don't
5132  have to build a new "zImage.initrd" Linux image when you just
5133  change a file in your "initrd"). Also, a field-upgrade of the
5134  software is easier now.
5135
5136
5137Linux HOWTO:
5138============
5139
5140Porting Linux to U-Boot based systems:
5141---------------------------------------
5142
5143U-Boot cannot save you from doing all the necessary modifications to
5144configure the Linux device drivers for use with your target hardware
5145(no, we don't intend to provide a full virtual machine interface to
5146Linux :-).
5147
5148But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
5149
5150Just make sure your machine specific header file (for instance
5151include/asm-ppc/tqm8xx.h) includes the same definition of the Board
5152Information structure as we define in include/asm-<arch>/u-boot.h,
5153and make sure that your definition of IMAP_ADDR uses the same value
5154as your U-Boot configuration in CONFIG_SYS_IMMR.
5155
5156Note that U-Boot now has a driver model, a unified model for drivers.
5157If you are adding a new driver, plumb it into driver model. If there
5158is no uclass available, you are encouraged to create one. See
5159doc/driver-model.
5160
5161
5162Configuring the Linux kernel:
5163-----------------------------
5164
5165No specific requirements for U-Boot. Make sure you have some root
5166device (initial ramdisk, NFS) for your target system.
5167
5168
5169Building a Linux Image:
5170-----------------------
5171
5172With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5173not used. If you use recent kernel source, a new build target
5174"uImage" will exist which automatically builds an image usable by
5175U-Boot. Most older kernels also have support for a "pImage" target,
5176which was introduced for our predecessor project PPCBoot and uses a
5177100% compatible format.
5178
5179Example:
5180
5181	make TQM850L_defconfig
5182	make oldconfig
5183	make dep
5184	make uImage
5185
5186The "uImage" build target uses a special tool (in 'tools/mkimage') to
5187encapsulate a compressed Linux kernel image with header	 information,
5188CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5189
5190* build a standard "vmlinux" kernel image (in ELF binary format):
5191
5192* convert the kernel into a raw binary image:
5193
5194	${CROSS_COMPILE}-objcopy -O binary \
5195				 -R .note -R .comment \
5196				 -S vmlinux linux.bin
5197
5198* compress the binary image:
5199
5200	gzip -9 linux.bin
5201
5202* package compressed binary image for U-Boot:
5203
5204	mkimage -A ppc -O linux -T kernel -C gzip \
5205		-a 0 -e 0 -n "Linux Kernel Image" \
5206		-d linux.bin.gz uImage
5207
5208
5209The "mkimage" tool can also be used to create ramdisk images for use
5210with U-Boot, either separated from the Linux kernel image, or
5211combined into one file. "mkimage" encapsulates the images with a 64
5212byte header containing information about target architecture,
5213operating system, image type, compression method, entry points, time
5214stamp, CRC32 checksums, etc.
5215
5216"mkimage" can be called in two ways: to verify existing images and
5217print the header information, or to build new images.
5218
5219In the first form (with "-l" option) mkimage lists the information
5220contained in the header of an existing U-Boot image; this includes
5221checksum verification:
5222
5223	tools/mkimage -l image
5224	  -l ==> list image header information
5225
5226The second form (with "-d" option) is used to build a U-Boot image
5227from a "data file" which is used as image payload:
5228
5229	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5230		      -n name -d data_file image
5231	  -A ==> set architecture to 'arch'
5232	  -O ==> set operating system to 'os'
5233	  -T ==> set image type to 'type'
5234	  -C ==> set compression type 'comp'
5235	  -a ==> set load address to 'addr' (hex)
5236	  -e ==> set entry point to 'ep' (hex)
5237	  -n ==> set image name to 'name'
5238	  -d ==> use image data from 'datafile'
5239
5240Right now, all Linux kernels for PowerPC systems use the same load
5241address (0x00000000), but the entry point address depends on the
5242kernel version:
5243
5244- 2.2.x kernels have the entry point at 0x0000000C,
5245- 2.3.x and later kernels have the entry point at 0x00000000.
5246
5247So a typical call to build a U-Boot image would read:
5248
5249	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5250	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5251	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5252	> examples/uImage.TQM850L
5253	Image Name:   2.4.4 kernel for TQM850L
5254	Created:      Wed Jul 19 02:34:59 2000
5255	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5256	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5257	Load Address: 0x00000000
5258	Entry Point:  0x00000000
5259
5260To verify the contents of the image (or check for corruption):
5261
5262	-> tools/mkimage -l examples/uImage.TQM850L
5263	Image Name:   2.4.4 kernel for TQM850L
5264	Created:      Wed Jul 19 02:34:59 2000
5265	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5266	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5267	Load Address: 0x00000000
5268	Entry Point:  0x00000000
5269
5270NOTE: for embedded systems where boot time is critical you can trade
5271speed for memory and install an UNCOMPRESSED image instead: this
5272needs more space in Flash, but boots much faster since it does not
5273need to be uncompressed:
5274
5275	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5276	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5277	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5278	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5279	> examples/uImage.TQM850L-uncompressed
5280	Image Name:   2.4.4 kernel for TQM850L
5281	Created:      Wed Jul 19 02:34:59 2000
5282	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5283	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5284	Load Address: 0x00000000
5285	Entry Point:  0x00000000
5286
5287
5288Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5289when your kernel is intended to use an initial ramdisk:
5290
5291	-> tools/mkimage -n 'Simple Ramdisk Image' \
5292	> -A ppc -O linux -T ramdisk -C gzip \
5293	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5294	Image Name:   Simple Ramdisk Image
5295	Created:      Wed Jan 12 14:01:50 2000
5296	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5297	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5298	Load Address: 0x00000000
5299	Entry Point:  0x00000000
5300
5301The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
5302option performs the converse operation of the mkimage's second form (the "-d"
5303option). Given an image built by mkimage, the dumpimage extracts a "data file"
5304from the image:
5305
5306	tools/dumpimage -i image -T type -p position data_file
5307	  -i ==> extract from the 'image' a specific 'data_file'
5308	  -T ==> set image type to 'type'
5309	  -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image'
5310
5311
5312Installing a Linux Image:
5313-------------------------
5314
5315To downloading a U-Boot image over the serial (console) interface,
5316you must convert the image to S-Record format:
5317
5318	objcopy -I binary -O srec examples/image examples/image.srec
5319
5320The 'objcopy' does not understand the information in the U-Boot
5321image header, so the resulting S-Record file will be relative to
5322address 0x00000000. To load it to a given address, you need to
5323specify the target address as 'offset' parameter with the 'loads'
5324command.
5325
5326Example: install the image to address 0x40100000 (which on the
5327TQM8xxL is in the first Flash bank):
5328
5329	=> erase 40100000 401FFFFF
5330
5331	.......... done
5332	Erased 8 sectors
5333
5334	=> loads 40100000
5335	## Ready for S-Record download ...
5336	~>examples/image.srec
5337	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5338	...
5339	15989 15990 15991 15992
5340	[file transfer complete]
5341	[connected]
5342	## Start Addr = 0x00000000
5343
5344
5345You can check the success of the download using the 'iminfo' command;
5346this includes a checksum verification so you can be sure no data
5347corruption happened:
5348
5349	=> imi 40100000
5350
5351	## Checking Image at 40100000 ...
5352	   Image Name:	 2.2.13 for initrd on TQM850L
5353	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5354	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5355	   Load Address: 00000000
5356	   Entry Point:	 0000000c
5357	   Verifying Checksum ... OK
5358
5359
5360Boot Linux:
5361-----------
5362
5363The "bootm" command is used to boot an application that is stored in
5364memory (RAM or Flash). In case of a Linux kernel image, the contents
5365of the "bootargs" environment variable is passed to the kernel as
5366parameters. You can check and modify this variable using the
5367"printenv" and "setenv" commands:
5368
5369
5370	=> printenv bootargs
5371	bootargs=root=/dev/ram
5372
5373	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5374
5375	=> printenv bootargs
5376	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5377
5378	=> bootm 40020000
5379	## Booting Linux kernel at 40020000 ...
5380	   Image Name:	 2.2.13 for NFS on TQM850L
5381	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5382	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5383	   Load Address: 00000000
5384	   Entry Point:	 0000000c
5385	   Verifying Checksum ... OK
5386	   Uncompressing Kernel Image ... OK
5387	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
5388	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5389	time_init: decrementer frequency = 187500000/60
5390	Calibrating delay loop... 49.77 BogoMIPS
5391	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5392	...
5393
5394If you want to boot a Linux kernel with initial RAM disk, you pass
5395the memory addresses of both the kernel and the initrd image (PPBCOOT
5396format!) to the "bootm" command:
5397
5398	=> imi 40100000 40200000
5399
5400	## Checking Image at 40100000 ...
5401	   Image Name:	 2.2.13 for initrd on TQM850L
5402	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5403	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5404	   Load Address: 00000000
5405	   Entry Point:	 0000000c
5406	   Verifying Checksum ... OK
5407
5408	## Checking Image at 40200000 ...
5409	   Image Name:	 Simple Ramdisk Image
5410	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5411	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5412	   Load Address: 00000000
5413	   Entry Point:	 00000000
5414	   Verifying Checksum ... OK
5415
5416	=> bootm 40100000 40200000
5417	## Booting Linux kernel at 40100000 ...
5418	   Image Name:	 2.2.13 for initrd on TQM850L
5419	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5420	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5421	   Load Address: 00000000
5422	   Entry Point:	 0000000c
5423	   Verifying Checksum ... OK
5424	   Uncompressing Kernel Image ... OK
5425	## Loading RAMDisk Image at 40200000 ...
5426	   Image Name:	 Simple Ramdisk Image
5427	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5428	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5429	   Load Address: 00000000
5430	   Entry Point:	 00000000
5431	   Verifying Checksum ... OK
5432	   Loading Ramdisk ... OK
5433	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
5434	Boot arguments: root=/dev/ram
5435	time_init: decrementer frequency = 187500000/60
5436	Calibrating delay loop... 49.77 BogoMIPS
5437	...
5438	RAMDISK: Compressed image found at block 0
5439	VFS: Mounted root (ext2 filesystem).
5440
5441	bash#
5442
5443Boot Linux and pass a flat device tree:
5444-----------
5445
5446First, U-Boot must be compiled with the appropriate defines. See the section
5447titled "Linux Kernel Interface" above for a more in depth explanation. The
5448following is an example of how to start a kernel and pass an updated
5449flat device tree:
5450
5451=> print oftaddr
5452oftaddr=0x300000
5453=> print oft
5454oft=oftrees/mpc8540ads.dtb
5455=> tftp $oftaddr $oft
5456Speed: 1000, full duplex
5457Using TSEC0 device
5458TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5459Filename 'oftrees/mpc8540ads.dtb'.
5460Load address: 0x300000
5461Loading: #
5462done
5463Bytes transferred = 4106 (100a hex)
5464=> tftp $loadaddr $bootfile
5465Speed: 1000, full duplex
5466Using TSEC0 device
5467TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5468Filename 'uImage'.
5469Load address: 0x200000
5470Loading:############
5471done
5472Bytes transferred = 1029407 (fb51f hex)
5473=> print loadaddr
5474loadaddr=200000
5475=> print oftaddr
5476oftaddr=0x300000
5477=> bootm $loadaddr - $oftaddr
5478## Booting image at 00200000 ...
5479   Image Name:	 Linux-2.6.17-dirty
5480   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5481   Data Size:	 1029343 Bytes = 1005.2 kB
5482   Load Address: 00000000
5483   Entry Point:	 00000000
5484   Verifying Checksum ... OK
5485   Uncompressing Kernel Image ... OK
5486Booting using flat device tree at 0x300000
5487Using MPC85xx ADS machine description
5488Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5489[snip]
5490
5491
5492More About U-Boot Image Types:
5493------------------------------
5494
5495U-Boot supports the following image types:
5496
5497   "Standalone Programs" are directly runnable in the environment
5498	provided by U-Boot; it is expected that (if they behave
5499	well) you can continue to work in U-Boot after return from
5500	the Standalone Program.
5501   "OS Kernel Images" are usually images of some Embedded OS which
5502	will take over control completely. Usually these programs
5503	will install their own set of exception handlers, device
5504	drivers, set up the MMU, etc. - this means, that you cannot
5505	expect to re-enter U-Boot except by resetting the CPU.
5506   "RAMDisk Images" are more or less just data blocks, and their
5507	parameters (address, size) are passed to an OS kernel that is
5508	being started.
5509   "Multi-File Images" contain several images, typically an OS
5510	(Linux) kernel image and one or more data images like
5511	RAMDisks. This construct is useful for instance when you want
5512	to boot over the network using BOOTP etc., where the boot
5513	server provides just a single image file, but you want to get
5514	for instance an OS kernel and a RAMDisk image.
5515
5516	"Multi-File Images" start with a list of image sizes, each
5517	image size (in bytes) specified by an "uint32_t" in network
5518	byte order. This list is terminated by an "(uint32_t)0".
5519	Immediately after the terminating 0 follow the images, one by
5520	one, all aligned on "uint32_t" boundaries (size rounded up to
5521	a multiple of 4 bytes).
5522
5523   "Firmware Images" are binary images containing firmware (like
5524	U-Boot or FPGA images) which usually will be programmed to
5525	flash memory.
5526
5527   "Script files" are command sequences that will be executed by
5528	U-Boot's command interpreter; this feature is especially
5529	useful when you configure U-Boot to use a real shell (hush)
5530	as command interpreter.
5531
5532Booting the Linux zImage:
5533-------------------------
5534
5535On some platforms, it's possible to boot Linux zImage. This is done
5536using the "bootz" command. The syntax of "bootz" command is the same
5537as the syntax of "bootm" command.
5538
5539Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5540kernel with raw initrd images. The syntax is slightly different, the
5541address of the initrd must be augmented by it's size, in the following
5542format: "<initrd addres>:<initrd size>".
5543
5544
5545Standalone HOWTO:
5546=================
5547
5548One of the features of U-Boot is that you can dynamically load and
5549run "standalone" applications, which can use some resources of
5550U-Boot like console I/O functions or interrupt services.
5551
5552Two simple examples are included with the sources:
5553
5554"Hello World" Demo:
5555-------------------
5556
5557'examples/hello_world.c' contains a small "Hello World" Demo
5558application; it is automatically compiled when you build U-Boot.
5559It's configured to run at address 0x00040004, so you can play with it
5560like that:
5561
5562	=> loads
5563	## Ready for S-Record download ...
5564	~>examples/hello_world.srec
5565	1 2 3 4 5 6 7 8 9 10 11 ...
5566	[file transfer complete]
5567	[connected]
5568	## Start Addr = 0x00040004
5569
5570	=> go 40004 Hello World! This is a test.
5571	## Starting application at 0x00040004 ...
5572	Hello World
5573	argc = 7
5574	argv[0] = "40004"
5575	argv[1] = "Hello"
5576	argv[2] = "World!"
5577	argv[3] = "This"
5578	argv[4] = "is"
5579	argv[5] = "a"
5580	argv[6] = "test."
5581	argv[7] = "<NULL>"
5582	Hit any key to exit ...
5583
5584	## Application terminated, rc = 0x0
5585
5586Another example, which demonstrates how to register a CPM interrupt
5587handler with the U-Boot code, can be found in 'examples/timer.c'.
5588Here, a CPM timer is set up to generate an interrupt every second.
5589The interrupt service routine is trivial, just printing a '.'
5590character, but this is just a demo program. The application can be
5591controlled by the following keys:
5592
5593	? - print current values og the CPM Timer registers
5594	b - enable interrupts and start timer
5595	e - stop timer and disable interrupts
5596	q - quit application
5597
5598	=> loads
5599	## Ready for S-Record download ...
5600	~>examples/timer.srec
5601	1 2 3 4 5 6 7 8 9 10 11 ...
5602	[file transfer complete]
5603	[connected]
5604	## Start Addr = 0x00040004
5605
5606	=> go 40004
5607	## Starting application at 0x00040004 ...
5608	TIMERS=0xfff00980
5609	Using timer 1
5610	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5611
5612Hit 'b':
5613	[q, b, e, ?] Set interval 1000000 us
5614	Enabling timer
5615Hit '?':
5616	[q, b, e, ?] ........
5617	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5618Hit '?':
5619	[q, b, e, ?] .
5620	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5621Hit '?':
5622	[q, b, e, ?] .
5623	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
5624Hit '?':
5625	[q, b, e, ?] .
5626	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
5627Hit 'e':
5628	[q, b, e, ?] ...Stopping timer
5629Hit 'q':
5630	[q, b, e, ?] ## Application terminated, rc = 0x0
5631
5632
5633Minicom warning:
5634================
5635
5636Over time, many people have reported problems when trying to use the
5637"minicom" terminal emulation program for serial download. I (wd)
5638consider minicom to be broken, and recommend not to use it. Under
5639Unix, I recommend to use C-Kermit for general purpose use (and
5640especially for kermit binary protocol download ("loadb" command), and
5641use "cu" for S-Record download ("loads" command).  See
5642http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
5643for help with kermit.
5644
5645
5646Nevertheless, if you absolutely want to use it try adding this
5647configuration to your "File transfer protocols" section:
5648
5649	   Name	   Program			Name U/D FullScr IO-Red. Multi
5650	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5651	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5652
5653
5654NetBSD Notes:
5655=============
5656
5657Starting at version 0.9.2, U-Boot supports NetBSD both as host
5658(build U-Boot) and target system (boots NetBSD/mpc8xx).
5659
5660Building requires a cross environment; it is known to work on
5661NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5662need gmake since the Makefiles are not compatible with BSD make).
5663Note that the cross-powerpc package does not install include files;
5664attempting to build U-Boot will fail because <machine/ansi.h> is
5665missing.  This file has to be installed and patched manually:
5666
5667	# cd /usr/pkg/cross/powerpc-netbsd/include
5668	# mkdir powerpc
5669	# ln -s powerpc machine
5670	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5671	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5672
5673Native builds *don't* work due to incompatibilities between native
5674and U-Boot include files.
5675
5676Booting assumes that (the first part of) the image booted is a
5677stage-2 loader which in turn loads and then invokes the kernel
5678proper. Loader sources will eventually appear in the NetBSD source
5679tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5680meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5681
5682
5683Implementation Internals:
5684=========================
5685
5686The following is not intended to be a complete description of every
5687implementation detail. However, it should help to understand the
5688inner workings of U-Boot and make it easier to port it to custom
5689hardware.
5690
5691
5692Initial Stack, Global Data:
5693---------------------------
5694
5695The implementation of U-Boot is complicated by the fact that U-Boot
5696starts running out of ROM (flash memory), usually without access to
5697system RAM (because the memory controller is not initialized yet).
5698This means that we don't have writable Data or BSS segments, and BSS
5699is not initialized as zero. To be able to get a C environment working
5700at all, we have to allocate at least a minimal stack. Implementation
5701options for this are defined and restricted by the CPU used: Some CPU
5702models provide on-chip memory (like the IMMR area on MPC8xx and
5703MPC826x processors), on others (parts of) the data cache can be
5704locked as (mis-) used as memory, etc.
5705
5706	Chris Hallinan posted a good summary of these issues to the
5707	U-Boot mailing list:
5708
5709	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
5710	From: "Chris Hallinan" <clh@net1plus.com>
5711	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
5712	...
5713
5714	Correct me if I'm wrong, folks, but the way I understand it
5715	is this: Using DCACHE as initial RAM for Stack, etc, does not
5716	require any physical RAM backing up the cache. The cleverness
5717	is that the cache is being used as a temporary supply of
5718	necessary storage before the SDRAM controller is setup. It's
5719	beyond the scope of this list to explain the details, but you
5720	can see how this works by studying the cache architecture and
5721	operation in the architecture and processor-specific manuals.
5722
5723	OCM is On Chip Memory, which I believe the 405GP has 4K. It
5724	is another option for the system designer to use as an
5725	initial stack/RAM area prior to SDRAM being available. Either
5726	option should work for you. Using CS 4 should be fine if your
5727	board designers haven't used it for something that would
5728	cause you grief during the initial boot! It is frequently not
5729	used.
5730
5731	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
5732	with your processor/board/system design. The default value
5733	you will find in any recent u-boot distribution in
5734	walnut.h should work for you. I'd set it to a value larger
5735	than your SDRAM module. If you have a 64MB SDRAM module, set
5736	it above 400_0000. Just make sure your board has no resources
5737	that are supposed to respond to that address! That code in
5738	start.S has been around a while and should work as is when
5739	you get the config right.
5740
5741	-Chris Hallinan
5742	DS4.COM, Inc.
5743
5744It is essential to remember this, since it has some impact on the C
5745code for the initialization procedures:
5746
5747* Initialized global data (data segment) is read-only. Do not attempt
5748  to write it.
5749
5750* Do not use any uninitialized global data (or implicitly initialized
5751  as zero data - BSS segment) at all - this is undefined, initiali-
5752  zation is performed later (when relocating to RAM).
5753
5754* Stack space is very limited. Avoid big data buffers or things like
5755  that.
5756
5757Having only the stack as writable memory limits means we cannot use
5758normal global data to share information between the code. But it
5759turned out that the implementation of U-Boot can be greatly
5760simplified by making a global data structure (gd_t) available to all
5761functions. We could pass a pointer to this data as argument to _all_
5762functions, but this would bloat the code. Instead we use a feature of
5763the GCC compiler (Global Register Variables) to share the data: we
5764place a pointer (gd) to the global data into a register which we
5765reserve for this purpose.
5766
5767When choosing a register for such a purpose we are restricted by the
5768relevant  (E)ABI  specifications for the current architecture, and by
5769GCC's implementation.
5770
5771For PowerPC, the following registers have specific use:
5772	R1:	stack pointer
5773	R2:	reserved for system use
5774	R3-R4:	parameter passing and return values
5775	R5-R10: parameter passing
5776	R13:	small data area pointer
5777	R30:	GOT pointer
5778	R31:	frame pointer
5779
5780	(U-Boot also uses R12 as internal GOT pointer. r12
5781	is a volatile register so r12 needs to be reset when
5782	going back and forth between asm and C)
5783
5784    ==> U-Boot will use R2 to hold a pointer to the global data
5785
5786    Note: on PPC, we could use a static initializer (since the
5787    address of the global data structure is known at compile time),
5788    but it turned out that reserving a register results in somewhat
5789    smaller code - although the code savings are not that big (on
5790    average for all boards 752 bytes for the whole U-Boot image,
5791    624 text + 127 data).
5792
5793On ARM, the following registers are used:
5794
5795	R0:	function argument word/integer result
5796	R1-R3:	function argument word
5797	R9:	platform specific
5798	R10:	stack limit (used only if stack checking is enabled)
5799	R11:	argument (frame) pointer
5800	R12:	temporary workspace
5801	R13:	stack pointer
5802	R14:	link register
5803	R15:	program counter
5804
5805    ==> U-Boot will use R9 to hold a pointer to the global data
5806
5807    Note: on ARM, only R_ARM_RELATIVE relocations are supported.
5808
5809On Nios II, the ABI is documented here:
5810	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
5811
5812    ==> U-Boot will use gp to hold a pointer to the global data
5813
5814    Note: on Nios II, we give "-G0" option to gcc and don't use gp
5815    to access small data sections, so gp is free.
5816
5817On NDS32, the following registers are used:
5818
5819	R0-R1:	argument/return
5820	R2-R5:	argument
5821	R15:	temporary register for assembler
5822	R16:	trampoline register
5823	R28:	frame pointer (FP)
5824	R29:	global pointer (GP)
5825	R30:	link register (LP)
5826	R31:	stack pointer (SP)
5827	PC:	program counter (PC)
5828
5829    ==> U-Boot will use R10 to hold a pointer to the global data
5830
5831NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
5832or current versions of GCC may "optimize" the code too much.
5833
5834Memory Management:
5835------------------
5836
5837U-Boot runs in system state and uses physical addresses, i.e. the
5838MMU is not used either for address mapping nor for memory protection.
5839
5840The available memory is mapped to fixed addresses using the memory
5841controller. In this process, a contiguous block is formed for each
5842memory type (Flash, SDRAM, SRAM), even when it consists of several
5843physical memory banks.
5844
5845U-Boot is installed in the first 128 kB of the first Flash bank (on
5846TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
5847booting and sizing and initializing DRAM, the code relocates itself
5848to the upper end of DRAM. Immediately below the U-Boot code some
5849memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
5850configuration setting]. Below that, a structure with global Board
5851Info data is placed, followed by the stack (growing downward).
5852
5853Additionally, some exception handler code is copied to the low 8 kB
5854of DRAM (0x00000000 ... 0x00001FFF).
5855
5856So a typical memory configuration with 16 MB of DRAM could look like
5857this:
5858
5859	0x0000 0000	Exception Vector code
5860	      :
5861	0x0000 1FFF
5862	0x0000 2000	Free for Application Use
5863	      :
5864	      :
5865
5866	      :
5867	      :
5868	0x00FB FF20	Monitor Stack (Growing downward)
5869	0x00FB FFAC	Board Info Data and permanent copy of global data
5870	0x00FC 0000	Malloc Arena
5871	      :
5872	0x00FD FFFF
5873	0x00FE 0000	RAM Copy of Monitor Code
5874	...		eventually: LCD or video framebuffer
5875	...		eventually: pRAM (Protected RAM - unchanged by reset)
5876	0x00FF FFFF	[End of RAM]
5877
5878
5879System Initialization:
5880----------------------
5881
5882In the reset configuration, U-Boot starts at the reset entry point
5883(on most PowerPC systems at address 0x00000100). Because of the reset
5884configuration for CS0# this is a mirror of the on board Flash memory.
5885To be able to re-map memory U-Boot then jumps to its link address.
5886To be able to implement the initialization code in C, a (small!)
5887initial stack is set up in the internal Dual Ported RAM (in case CPUs
5888which provide such a feature like MPC8xx or MPC8260), or in a locked
5889part of the data cache. After that, U-Boot initializes the CPU core,
5890the caches and the SIU.
5891
5892Next, all (potentially) available memory banks are mapped using a
5893preliminary mapping. For example, we put them on 512 MB boundaries
5894(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
5895on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
5896programmed for SDRAM access. Using the temporary configuration, a
5897simple memory test is run that determines the size of the SDRAM
5898banks.
5899
5900When there is more than one SDRAM bank, and the banks are of
5901different size, the largest is mapped first. For equal size, the first
5902bank (CS2#) is mapped first. The first mapping is always for address
59030x00000000, with any additional banks following immediately to create
5904contiguous memory starting from 0.
5905
5906Then, the monitor installs itself at the upper end of the SDRAM area
5907and allocates memory for use by malloc() and for the global Board
5908Info data; also, the exception vector code is copied to the low RAM
5909pages, and the final stack is set up.
5910
5911Only after this relocation will you have a "normal" C environment;
5912until that you are restricted in several ways, mostly because you are
5913running from ROM, and because the code will have to be relocated to a
5914new address in RAM.
5915
5916
5917U-Boot Porting Guide:
5918----------------------
5919
5920[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
5921list, October 2002]
5922
5923
5924int main(int argc, char *argv[])
5925{
5926	sighandler_t no_more_time;
5927
5928	signal(SIGALRM, no_more_time);
5929	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
5930
5931	if (available_money > available_manpower) {
5932		Pay consultant to port U-Boot;
5933		return 0;
5934	}
5935
5936	Download latest U-Boot source;
5937
5938	Subscribe to u-boot mailing list;
5939
5940	if (clueless)
5941		email("Hi, I am new to U-Boot, how do I get started?");
5942
5943	while (learning) {
5944		Read the README file in the top level directory;
5945		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
5946		Read applicable doc/*.README;
5947		Read the source, Luke;
5948		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
5949	}
5950
5951	if (available_money > toLocalCurrency ($2500))
5952		Buy a BDI3000;
5953	else
5954		Add a lot of aggravation and time;
5955
5956	if (a similar board exists) {	/* hopefully... */
5957		cp -a board/<similar> board/<myboard>
5958		cp include/configs/<similar>.h include/configs/<myboard>.h
5959	} else {
5960		Create your own board support subdirectory;
5961		Create your own board include/configs/<myboard>.h file;
5962	}
5963	Edit new board/<myboard> files
5964	Edit new include/configs/<myboard>.h
5965
5966	while (!accepted) {
5967		while (!running) {
5968			do {
5969				Add / modify source code;
5970			} until (compiles);
5971			Debug;
5972			if (clueless)
5973				email("Hi, I am having problems...");
5974		}
5975		Send patch file to the U-Boot email list;
5976		if (reasonable critiques)
5977			Incorporate improvements from email list code review;
5978		else
5979			Defend code as written;
5980	}
5981
5982	return 0;
5983}
5984
5985void no_more_time (int sig)
5986{
5987      hire_a_guru();
5988}
5989
5990
5991Coding Standards:
5992-----------------
5993
5994All contributions to U-Boot should conform to the Linux kernel
5995coding style; see the file "Documentation/CodingStyle" and the script
5996"scripts/Lindent" in your Linux kernel source directory.
5997
5998Source files originating from a different project (for example the
5999MTD subsystem) are generally exempt from these guidelines and are not
6000reformatted to ease subsequent migration to newer versions of those
6001sources.
6002
6003Please note that U-Boot is implemented in C (and to some small parts in
6004Assembler); no C++ is used, so please do not use C++ style comments (//)
6005in your code.
6006
6007Please also stick to the following formatting rules:
6008- remove any trailing white space
6009- use TAB characters for indentation and vertical alignment, not spaces
6010- make sure NOT to use DOS '\r\n' line feeds
6011- do not add more than 2 consecutive empty lines to source files
6012- do not add trailing empty lines to source files
6013
6014Submissions which do not conform to the standards may be returned
6015with a request to reformat the changes.
6016
6017
6018Submitting Patches:
6019-------------------
6020
6021Since the number of patches for U-Boot is growing, we need to
6022establish some rules. Submissions which do not conform to these rules
6023may be rejected, even when they contain important and valuable stuff.
6024
6025Please see http://www.denx.de/wiki/U-Boot/Patches for details.
6026
6027Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
6028see http://lists.denx.de/mailman/listinfo/u-boot
6029
6030When you send a patch, please include the following information with
6031it:
6032
6033* For bug fixes: a description of the bug and how your patch fixes
6034  this bug. Please try to include a way of demonstrating that the
6035  patch actually fixes something.
6036
6037* For new features: a description of the feature and your
6038  implementation.
6039
6040* A CHANGELOG entry as plaintext (separate from the patch)
6041
6042* For major contributions, add a MAINTAINERS file with your
6043  information and associated file and directory references.
6044
6045* When you add support for a new board, don't forget to add a
6046  maintainer e-mail address to the boards.cfg file, too.
6047
6048* If your patch adds new configuration options, don't forget to
6049  document these in the README file.
6050
6051* The patch itself. If you are using git (which is *strongly*
6052  recommended) you can easily generate the patch using the
6053  "git format-patch". If you then use "git send-email" to send it to
6054  the U-Boot mailing list, you will avoid most of the common problems
6055  with some other mail clients.
6056
6057  If you cannot use git, use "diff -purN OLD NEW". If your version of
6058  diff does not support these options, then get the latest version of
6059  GNU diff.
6060
6061  The current directory when running this command shall be the parent
6062  directory of the U-Boot source tree (i. e. please make sure that
6063  your patch includes sufficient directory information for the
6064  affected files).
6065
6066  We prefer patches as plain text. MIME attachments are discouraged,
6067  and compressed attachments must not be used.
6068
6069* If one logical set of modifications affects or creates several
6070  files, all these changes shall be submitted in a SINGLE patch file.
6071
6072* Changesets that contain different, unrelated modifications shall be
6073  submitted as SEPARATE patches, one patch per changeset.
6074
6075
6076Notes:
6077
6078* Before sending the patch, run the buildman script on your patched
6079  source tree and make sure that no errors or warnings are reported
6080  for any of the boards.
6081
6082* Keep your modifications to the necessary minimum: A patch
6083  containing several unrelated changes or arbitrary reformats will be
6084  returned with a request to re-formatting / split it.
6085
6086* If you modify existing code, make sure that your new code does not
6087  add to the memory footprint of the code ;-) Small is beautiful!
6088  When adding new features, these should compile conditionally only
6089  (using #ifdef), and the resulting code with the new feature
6090  disabled must not need more memory than the old code without your
6091  modification.
6092
6093* Remember that there is a size limit of 100 kB per message on the
6094  u-boot mailing list. Bigger patches will be moderated. If they are
6095  reasonable and not too big, they will be acknowledged. But patches
6096  bigger than the size limit should be avoided.
6097