xref: /openbmc/u-boot/README (revision e183a174)
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 and CREDITS files to find out
38who contributed the specific port. The boards.cfg file lists board
39maintainers.
40
41Note: There is no CHANGELOG file in the actual U-Boot source tree;
42it can be created dynamically from the Git log using:
43
44	make CHANGELOG
45
46
47Where to get help:
48==================
49
50In case you have questions about, problems with or contributions for
51U-Boot you should send a message to the U-Boot mailing list at
52<u-boot@lists.denx.de>. There is also an archive of previous traffic
53on the mailing list - please search the archive before asking FAQ's.
54Please see http://lists.denx.de/pipermail/u-boot and
55http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
56
57
58Where to get source code:
59=========================
60
61The U-Boot source code is maintained in the git repository at
62git://www.denx.de/git/u-boot.git ; you can browse it online at
63http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
64
65The "snapshot" links on this page allow you to download tarballs of
66any version you might be interested in. Official releases are also
67available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
68directory.
69
70Pre-built (and tested) images are available from
71ftp://ftp.denx.de/pub/u-boot/images/
72
73
74Where we come from:
75===================
76
77- start from 8xxrom sources
78- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
79- clean up code
80- make it easier to add custom boards
81- make it possible to add other [PowerPC] CPUs
82- extend functions, especially:
83  * Provide extended interface to Linux boot loader
84  * S-Record download
85  * network boot
86  * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
87- create ARMBoot project (http://sourceforge.net/projects/armboot)
88- add other CPU families (starting with ARM)
89- create U-Boot project (http://sourceforge.net/projects/u-boot)
90- current project page: see http://www.denx.de/wiki/U-Boot
91
92
93Names and Spelling:
94===================
95
96The "official" name of this project is "Das U-Boot". The spelling
97"U-Boot" shall be used in all written text (documentation, comments
98in source files etc.). Example:
99
100	This is the README file for the U-Boot project.
101
102File names etc. shall be based on the string "u-boot". Examples:
103
104	include/asm-ppc/u-boot.h
105
106	#include <asm/u-boot.h>
107
108Variable names, preprocessor constants etc. shall be either based on
109the string "u_boot" or on "U_BOOT". Example:
110
111	U_BOOT_VERSION		u_boot_logo
112	IH_OS_U_BOOT		u_boot_hush_start
113
114
115Versioning:
116===========
117
118Starting with the release in October 2008, the names of the releases
119were changed from numerical release numbers without deeper meaning
120into a time stamp based numbering. Regular releases are identified by
121names consisting of the calendar year and month of the release date.
122Additional fields (if present) indicate release candidates or bug fix
123releases in "stable" maintenance trees.
124
125Examples:
126	U-Boot v2009.11	    - Release November 2009
127	U-Boot v2009.11.1   - Release 1 in version November 2009 stable tree
128	U-Boot v2010.09-rc1 - Release candiate 1 for September 2010 release
129
130
131Directory Hierarchy:
132====================
133
134/arch			Architecture specific files
135  /arm			Files generic to ARM architecture
136    /cpu		CPU specific files
137      /arm720t		Files specific to ARM 720 CPUs
138      /arm920t		Files specific to ARM 920 CPUs
139	/at91		Files specific to Atmel AT91RM9200 CPU
140	/imx		Files specific to Freescale MC9328 i.MX CPUs
141	/s3c24x0	Files specific to Samsung S3C24X0 CPUs
142      /arm926ejs	Files specific to ARM 926 CPUs
143      /arm1136		Files specific to ARM 1136 CPUs
144      /ixp		Files specific to Intel XScale IXP CPUs
145      /pxa		Files specific to Intel XScale PXA CPUs
146      /sa1100		Files specific to Intel StrongARM SA1100 CPUs
147    /lib		Architecture specific library files
148  /avr32		Files generic to AVR32 architecture
149    /cpu		CPU specific files
150    /lib		Architecture specific library files
151  /blackfin		Files generic to Analog Devices Blackfin architecture
152    /cpu		CPU specific files
153    /lib		Architecture specific library files
154  /m68k			Files generic to m68k architecture
155    /cpu		CPU specific files
156      /mcf52x2		Files specific to Freescale ColdFire MCF52x2 CPUs
157      /mcf5227x		Files specific to Freescale ColdFire MCF5227x CPUs
158      /mcf532x		Files specific to Freescale ColdFire MCF5329 CPUs
159      /mcf5445x		Files specific to Freescale ColdFire MCF5445x CPUs
160      /mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
161    /lib		Architecture specific library files
162  /microblaze		Files generic to microblaze architecture
163    /cpu		CPU specific files
164    /lib		Architecture specific library files
165  /mips			Files generic to MIPS architecture
166    /cpu		CPU specific files
167      /mips32		Files specific to MIPS32 CPUs
168      /xburst		Files specific to Ingenic XBurst CPUs
169    /lib		Architecture specific library files
170  /nds32		Files generic to NDS32 architecture
171    /cpu		CPU specific files
172      /n1213		Files specific to Andes Technology N1213 CPUs
173    /lib		Architecture specific library files
174  /nios2		Files generic to Altera NIOS2 architecture
175    /cpu		CPU specific files
176    /lib		Architecture specific library files
177  /openrisc		Files generic to OpenRISC architecture
178    /cpu		CPU specific files
179    /lib		Architecture specific library files
180  /powerpc		Files generic to PowerPC architecture
181    /cpu		CPU specific files
182      /74xx_7xx		Files specific to Freescale MPC74xx and 7xx CPUs
183      /mpc5xx		Files specific to Freescale MPC5xx CPUs
184      /mpc5xxx		Files specific to Freescale MPC5xxx CPUs
185      /mpc8xx		Files specific to Freescale MPC8xx CPUs
186      /mpc824x		Files specific to Freescale MPC824x CPUs
187      /mpc8260		Files specific to Freescale MPC8260 CPUs
188      /mpc85xx		Files specific to Freescale MPC85xx CPUs
189      /ppc4xx		Files specific to AMCC PowerPC 4xx CPUs
190    /lib		Architecture specific library files
191  /sh			Files generic to SH architecture
192    /cpu		CPU specific files
193      /sh2		Files specific to sh2 CPUs
194      /sh3		Files specific to sh3 CPUs
195      /sh4		Files specific to sh4 CPUs
196    /lib		Architecture specific library files
197  /sparc		Files generic to SPARC architecture
198    /cpu		CPU specific files
199      /leon2		Files specific to Gaisler LEON2 SPARC CPU
200      /leon3		Files specific to Gaisler LEON3 SPARC CPU
201    /lib		Architecture specific library files
202  /x86			Files generic to x86 architecture
203    /cpu		CPU specific files
204    /lib		Architecture specific library files
205/api			Machine/arch independent API for external apps
206/board			Board dependent files
207/common			Misc architecture independent functions
208/disk			Code for disk drive partition handling
209/doc			Documentation (don't expect too much)
210/drivers		Commonly used device drivers
211/dts			Contains Makefile for building internal U-Boot fdt.
212/examples		Example code for standalone applications, etc.
213/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
214/include		Header Files
215/lib			Files generic to all architectures
216  /libfdt		Library files to support flattened device trees
217  /lzma			Library files to support LZMA decompression
218  /lzo			Library files to support LZO decompression
219/net			Networking code
220/post			Power On Self Test
221/spl			Secondary Program Loader framework
222/tools			Tools to build S-Record or U-Boot images, etc.
223
224Software Configuration:
225=======================
226
227Configuration is usually done using C preprocessor defines; the
228rationale behind that is to avoid dead code whenever possible.
229
230There are two classes of configuration variables:
231
232* Configuration _OPTIONS_:
233  These are selectable by the user and have names beginning with
234  "CONFIG_".
235
236* Configuration _SETTINGS_:
237  These depend on the hardware etc. and should not be meddled with if
238  you don't know what you're doing; they have names beginning with
239  "CONFIG_SYS_".
240
241Later we will add a configuration tool - probably similar to or even
242identical to what's used for the Linux kernel. Right now, we have to
243do the configuration by hand, which means creating some symbolic
244links and editing some configuration files. We use the TQM8xxL boards
245as an example here.
246
247
248Selection of Processor Architecture and Board Type:
249---------------------------------------------------
250
251For all supported boards there are ready-to-use default
252configurations available; just type "make <board_name>_config".
253
254Example: For a TQM823L module type:
255
256	cd u-boot
257	make TQM823L_config
258
259For the Cogent platform, you need to specify the CPU type as well;
260e.g. "make cogent_mpc8xx_config". And also configure the cogent
261directory according to the instructions in cogent/README.
262
263
264Configuration Options:
265----------------------
266
267Configuration depends on the combination of board and CPU type; all
268such information is kept in a configuration file
269"include/configs/<board_name>.h".
270
271Example: For a TQM823L module, all configuration settings are in
272"include/configs/TQM823L.h".
273
274
275Many of the options are named exactly as the corresponding Linux
276kernel configuration options. The intention is to make it easier to
277build a config tool - later.
278
279
280The following options need to be configured:
281
282- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
283
284- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
285
286- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
287		Define exactly one, e.g. CONFIG_ATSTK1002
288
289- CPU Module Type: (if CONFIG_COGENT is defined)
290		Define exactly one of
291		CONFIG_CMA286_60_OLD
292--- FIXME --- not tested yet:
293		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
294		CONFIG_CMA287_23, CONFIG_CMA287_50
295
296- Motherboard Type: (if CONFIG_COGENT is defined)
297		Define exactly one of
298		CONFIG_CMA101, CONFIG_CMA102
299
300- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
301		Define one or more of
302		CONFIG_CMA302
303
304- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
305		Define one or more of
306		CONFIG_LCD_HEARTBEAT	- update a character position on
307					  the LCD display every second with
308					  a "rotator" |\-/|\-/
309
310- Board flavour: (if CONFIG_MPC8260ADS is defined)
311		CONFIG_ADSTYPE
312		Possible values are:
313			CONFIG_SYS_8260ADS	- original MPC8260ADS
314			CONFIG_SYS_8266ADS	- MPC8266ADS
315			CONFIG_SYS_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
316			CONFIG_SYS_8272ADS	- MPC8272ADS
317
318- Marvell Family Member
319		CONFIG_SYS_MVFS		- define it if you want to enable
320					  multiple fs option at one time
321					  for marvell soc family
322
323- MPC824X Family Member (if CONFIG_MPC824X is defined)
324		Define exactly one of
325		CONFIG_MPC8240, CONFIG_MPC8245
326
327- 8xx CPU Options: (if using an MPC8xx CPU)
328		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
329					  get_gclk_freq() cannot work
330					  e.g. if there is no 32KHz
331					  reference PIT/RTC clock
332		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
333					  or XTAL/EXTAL)
334
335- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
336		CONFIG_SYS_8xx_CPUCLK_MIN
337		CONFIG_SYS_8xx_CPUCLK_MAX
338		CONFIG_8xx_CPUCLK_DEFAULT
339			See doc/README.MPC866
340
341		CONFIG_SYS_MEASURE_CPUCLK
342
343		Define this to measure the actual CPU clock instead
344		of relying on the correctness of the configured
345		values. Mostly useful for board bringup to make sure
346		the PLL is locked at the intended frequency. Note
347		that this requires a (stable) reference clock (32 kHz
348		RTC clock or CONFIG_SYS_8XX_XIN)
349
350		CONFIG_SYS_DELAYED_ICACHE
351
352		Define this option if you want to enable the
353		ICache only when Code runs from RAM.
354
355- 85xx CPU Options:
356		CONFIG_SYS_PPC64
357
358		Specifies that the core is a 64-bit PowerPC implementation (implements
359		the "64" category of the Power ISA). This is necessary for ePAPR
360		compliance, among other possible reasons.
361
362		CONFIG_SYS_FSL_TBCLK_DIV
363
364		Defines the core time base clock divider ratio compared to the
365		system clock.  On most PQ3 devices this is 8, on newer QorIQ
366		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
367
368		CONFIG_SYS_FSL_PCIE_COMPAT
369
370		Defines the string to utilize when trying to match PCIe device
371		tree nodes for the given platform.
372
373		CONFIG_SYS_PPC_E500_DEBUG_TLB
374
375		Enables a temporary TLB entry to be used during boot to work
376		around limitations in e500v1 and e500v2 external debugger
377		support. This reduces the portions of the boot code where
378		breakpoints and single stepping do not work.  The value of this
379		symbol should be set to the TLB1 entry to be used for this
380		purpose.
381
382		CONFIG_SYS_FSL_ERRATUM_A004510
383
384		Enables a workaround for erratum A004510.  If set,
385		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
386		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
387
388		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
389		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
390
391		Defines one or two SoC revisions (low 8 bits of SVR)
392		for which the A004510 workaround should be applied.
393
394		The rest of SVR is either not relevant to the decision
395		of whether the erratum is present (e.g. p2040 versus
396		p2041) or is implied by the build target, which controls
397		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
398
399		See Freescale App Note 4493 for more information about
400		this erratum.
401
402		CONFIG_A003399_NOR_WORKAROUND
403		Enables a workaround for IFC erratum A003399. It is only
404		requred during NOR boot.
405
406		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
407
408		This is the value to write into CCSR offset 0x18600
409		according to the A004510 workaround.
410
411		CONFIG_SYS_FSL_DSP_DDR_ADDR
412		This value denotes start offset of DDR memory which is
413		connected exclusively to the DSP cores.
414
415		CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
416		This value denotes start offset of M2 memory
417		which is directly connected to the DSP core.
418
419		CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
420		This value denotes start offset of M3 memory which is directly
421		connected to the DSP core.
422
423		CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
424		This value denotes start offset of DSP CCSR space.
425
426		CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
427		Single Source Clock is clocking mode present in some of FSL SoC's.
428		In this mode, a single differential clock is used to supply
429		clocks to the sysclock, ddrclock and usbclock.
430
431- Generic CPU options:
432		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
433
434		Defines the endianess of the CPU. Implementation of those
435		values is arch specific.
436
437		CONFIG_SYS_FSL_DDR
438		Freescale DDR driver in use. This type of DDR controller is
439		found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
440		SoCs.
441
442		CONFIG_SYS_FSL_DDR_ADDR
443		Freescale DDR memory-mapped register base.
444
445		CONFIG_SYS_FSL_DDR_EMU
446		Specify emulator support for DDR. Some DDR features such as
447		deskew training are not available.
448
449		CONFIG_SYS_FSL_DDRC_GEN1
450		Freescale DDR1 controller.
451
452		CONFIG_SYS_FSL_DDRC_GEN2
453		Freescale DDR2 controller.
454
455		CONFIG_SYS_FSL_DDRC_GEN3
456		Freescale DDR3 controller.
457
458		CONFIG_SYS_FSL_DDRC_ARM_GEN3
459		Freescale DDR3 controller for ARM-based SoCs.
460
461		CONFIG_SYS_FSL_DDR1
462		Board config to use DDR1. It can be enabled for SoCs with
463		Freescale DDR1 or DDR2 controllers, depending on the board
464		implemetation.
465
466		CONFIG_SYS_FSL_DDR2
467		Board config to use DDR2. It can be eanbeld for SoCs with
468		Freescale DDR2 or DDR3 controllers, depending on the board
469		implementation.
470
471		CONFIG_SYS_FSL_DDR3
472		Board config to use DDR3. It can be enabled for SoCs with
473		Freescale DDR3 controllers.
474
475		CONFIG_SYS_FSL_IFC_BE
476		Defines the IFC controller register space as Big Endian
477
478		CONFIG_SYS_FSL_IFC_LE
479		Defines the IFC controller register space as Little Endian
480
481		CONFIG_SYS_FSL_PBL_PBI
482		It enables addition of RCW (Power on reset configuration) in built image.
483		Please refer doc/README.pblimage for more details
484
485		CONFIG_SYS_FSL_PBL_RCW
486		It adds PBI(pre-boot instructions) commands in u-boot build image.
487		PBI commands can be used to configure SoC before it starts the execution.
488		Please refer doc/README.pblimage for more details
489
490- Intel Monahans options:
491		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
492
493		Defines the Monahans run mode to oscillator
494		ratio. Valid values are 8, 16, 24, 31. The core
495		frequency is this value multiplied by 13 MHz.
496
497		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
498
499		Defines the Monahans turbo mode to oscillator
500		ratio. Valid values are 1 (default if undefined) and
501		2. The core frequency as calculated above is multiplied
502		by this value.
503
504- MIPS CPU options:
505		CONFIG_SYS_INIT_SP_OFFSET
506
507		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
508		pointer. This is needed for the temporary stack before
509		relocation.
510
511		CONFIG_SYS_MIPS_CACHE_MODE
512
513		Cache operation mode for the MIPS CPU.
514		See also arch/mips/include/asm/mipsregs.h.
515		Possible values are:
516			CONF_CM_CACHABLE_NO_WA
517			CONF_CM_CACHABLE_WA
518			CONF_CM_UNCACHED
519			CONF_CM_CACHABLE_NONCOHERENT
520			CONF_CM_CACHABLE_CE
521			CONF_CM_CACHABLE_COW
522			CONF_CM_CACHABLE_CUW
523			CONF_CM_CACHABLE_ACCELERATED
524
525		CONFIG_SYS_XWAY_EBU_BOOTCFG
526
527		Special option for Lantiq XWAY SoCs for booting from NOR flash.
528		See also arch/mips/cpu/mips32/start.S.
529
530		CONFIG_XWAY_SWAP_BYTES
531
532		Enable compilation of tools/xway-swap-bytes needed for Lantiq
533		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
534		be swapped if a flash programmer is used.
535
536- ARM options:
537		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
538
539		Select high exception vectors of the ARM core, e.g., do not
540		clear the V bit of the c1 register of CP15.
541
542		CONFIG_SYS_THUMB_BUILD
543
544		Use this flag to build U-Boot using the Thumb instruction
545		set for ARM architectures. Thumb instruction set provides
546		better code density. For ARM architectures that support
547		Thumb2 this flag will result in Thumb2 code generated by
548		GCC.
549
550		CONFIG_ARM_ERRATA_716044
551		CONFIG_ARM_ERRATA_742230
552		CONFIG_ARM_ERRATA_743622
553		CONFIG_ARM_ERRATA_751472
554
555		If set, the workarounds for these ARM errata are applied early
556		during U-Boot startup. Note that these options force the
557		workarounds to be applied; no CPU-type/version detection
558		exists, unlike the similar options in the Linux kernel. Do not
559		set these options unless they apply!
560
561- CPU timer options:
562		CONFIG_SYS_HZ
563
564		The frequency of the timer returned by get_timer().
565		get_timer() must operate in milliseconds and this CONFIG
566		option must be set to 1000.
567
568- Linux Kernel Interface:
569		CONFIG_CLOCKS_IN_MHZ
570
571		U-Boot stores all clock information in Hz
572		internally. For binary compatibility with older Linux
573		kernels (which expect the clocks passed in the
574		bd_info data to be in MHz) the environment variable
575		"clocks_in_mhz" can be defined so that U-Boot
576		converts clock data to MHZ before passing it to the
577		Linux kernel.
578		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
579		"clocks_in_mhz=1" is automatically included in the
580		default environment.
581
582		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
583
584		When transferring memsize parameter to linux, some versions
585		expect it to be in bytes, others in MB.
586		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
587
588		CONFIG_OF_LIBFDT
589
590		New kernel versions are expecting firmware settings to be
591		passed using flattened device trees (based on open firmware
592		concepts).
593
594		CONFIG_OF_LIBFDT
595		 * New libfdt-based support
596		 * Adds the "fdt" command
597		 * The bootm command automatically updates the fdt
598
599		OF_CPU - The proper name of the cpus node (only required for
600			MPC512X and MPC5xxx based boards).
601		OF_SOC - The proper name of the soc node (only required for
602			MPC512X and MPC5xxx based boards).
603		OF_TBCLK - The timebase frequency.
604		OF_STDOUT_PATH - The path to the console device
605
606		boards with QUICC Engines require OF_QE to set UCC MAC
607		addresses
608
609		CONFIG_OF_BOARD_SETUP
610
611		Board code has addition modification that it wants to make
612		to the flat device tree before handing it off to the kernel
613
614		CONFIG_OF_BOOT_CPU
615
616		This define fills in the correct boot CPU in the boot
617		param header, the default value is zero if undefined.
618
619		CONFIG_OF_IDE_FIXUP
620
621		U-Boot can detect if an IDE device is present or not.
622		If not, and this new config option is activated, U-Boot
623		removes the ATA node from the DTS before booting Linux,
624		so the Linux IDE driver does not probe the device and
625		crash. This is needed for buggy hardware (uc101) where
626		no pull down resistor is connected to the signal IDE5V_DD7.
627
628		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
629
630		This setting is mandatory for all boards that have only one
631		machine type and must be used to specify the machine type
632		number as it appears in the ARM machine registry
633		(see http://www.arm.linux.org.uk/developer/machines/).
634		Only boards that have multiple machine types supported
635		in a single configuration file and the machine type is
636		runtime discoverable, do not have to use this setting.
637
638- vxWorks boot parameters:
639
640		bootvx constructs a valid bootline using the following
641		environments variables: bootfile, ipaddr, serverip, hostname.
642		It loads the vxWorks image pointed bootfile.
643
644		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
645		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
646		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
647		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
648
649		CONFIG_SYS_VXWORKS_ADD_PARAMS
650
651		Add it at the end of the bootline. E.g "u=username pw=secret"
652
653		Note: If a "bootargs" environment is defined, it will overwride
654		the defaults discussed just above.
655
656- Cache Configuration:
657		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
658		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
659		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
660
661- Cache Configuration for ARM:
662		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
663				      controller
664		CONFIG_SYS_PL310_BASE - Physical base address of PL310
665					controller register space
666
667- Serial Ports:
668		CONFIG_PL010_SERIAL
669
670		Define this if you want support for Amba PrimeCell PL010 UARTs.
671
672		CONFIG_PL011_SERIAL
673
674		Define this if you want support for Amba PrimeCell PL011 UARTs.
675
676		CONFIG_PL011_CLOCK
677
678		If you have Amba PrimeCell PL011 UARTs, set this variable to
679		the clock speed of the UARTs.
680
681		CONFIG_PL01x_PORTS
682
683		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
684		define this to a list of base addresses for each (supported)
685		port. See e.g. include/configs/versatile.h
686
687		CONFIG_PL011_SERIAL_RLCR
688
689		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
690		have separate receive and transmit line control registers.  Set
691		this variable to initialize the extra register.
692
693		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
694
695		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
696		boot loader that has already initialized the UART.  Define this
697		variable to flush the UART at init time.
698
699
700- Console Interface:
701		Depending on board, define exactly one serial port
702		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
703		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
704		console by defining CONFIG_8xx_CONS_NONE
705
706		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
707		port routines must be defined elsewhere
708		(i.e. serial_init(), serial_getc(), ...)
709
710		CONFIG_CFB_CONSOLE
711		Enables console device for a color framebuffer. Needs following
712		defines (cf. smiLynxEM, i8042)
713			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
714						(default big endian)
715			VIDEO_HW_RECTFILL	graphic chip supports
716						rectangle fill
717						(cf. smiLynxEM)
718			VIDEO_HW_BITBLT		graphic chip supports
719						bit-blit (cf. smiLynxEM)
720			VIDEO_VISIBLE_COLS	visible pixel columns
721						(cols=pitch)
722			VIDEO_VISIBLE_ROWS	visible pixel rows
723			VIDEO_PIXEL_SIZE	bytes per pixel
724			VIDEO_DATA_FORMAT	graphic data format
725						(0-5, cf. cfb_console.c)
726			VIDEO_FB_ADRS		framebuffer address
727			VIDEO_KBD_INIT_FCT	keyboard int fct
728						(i.e. i8042_kbd_init())
729			VIDEO_TSTC_FCT		test char fct
730						(i.e. i8042_tstc)
731			VIDEO_GETC_FCT		get char fct
732						(i.e. i8042_getc)
733			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
734						(requires blink timer
735						cf. i8042.c)
736			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
737			CONFIG_CONSOLE_TIME	display time/date info in
738						upper right corner
739						(requires CONFIG_CMD_DATE)
740			CONFIG_VIDEO_LOGO	display Linux logo in
741						upper left corner
742			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
743						linux_logo.h for logo.
744						Requires CONFIG_VIDEO_LOGO
745			CONFIG_CONSOLE_EXTRA_INFO
746						additional board info beside
747						the logo
748
749		When CONFIG_CFB_CONSOLE_ANSI is defined, console will support
750		a limited number of ANSI escape sequences (cursor control,
751		erase functions and limited graphics rendition control).
752
753		When CONFIG_CFB_CONSOLE is defined, video console is
754		default i/o. Serial console can be forced with
755		environment 'console=serial'.
756
757		When CONFIG_SILENT_CONSOLE is defined, all console
758		messages (by U-Boot and Linux!) can be silenced with
759		the "silent" environment variable. See
760		doc/README.silent for more information.
761
762		CONFIG_SYS_CONSOLE_BG_COL: define the backgroundcolor, default
763			is 0x00.
764		CONFIG_SYS_CONSOLE_FG_COL: define the foregroundcolor, default
765			is 0xa0.
766
767- Console Baudrate:
768		CONFIG_BAUDRATE - in bps
769		Select one of the baudrates listed in
770		CONFIG_SYS_BAUDRATE_TABLE, see below.
771		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
772
773- Console Rx buffer length
774		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
775		the maximum receive buffer length for the SMC.
776		This option is actual only for 82xx and 8xx possible.
777		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
778		must be defined, to setup the maximum idle timeout for
779		the SMC.
780
781- Pre-Console Buffer:
782		Prior to the console being initialised (i.e. serial UART
783		initialised etc) all console output is silently discarded.
784		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
785		buffer any console messages prior to the console being
786		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
787		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
788		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
789		bytes are output before the console is initialised, the
790		earlier bytes are discarded.
791
792		'Sane' compilers will generate smaller code if
793		CONFIG_PRE_CON_BUF_SZ is a power of 2
794
795- Safe printf() functions
796		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
797		the printf() functions. These are defined in
798		include/vsprintf.h and include snprintf(), vsnprintf() and
799		so on. Code size increase is approximately 300-500 bytes.
800		If this option is not given then these functions will
801		silently discard their buffer size argument - this means
802		you are not getting any overflow checking in this case.
803
804- Boot Delay:	CONFIG_BOOTDELAY - in seconds
805		Delay before automatically booting the default image;
806		set to -1 to disable autoboot.
807		set to -2 to autoboot with no delay and not check for abort
808		(even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).
809
810		See doc/README.autoboot for these options that
811		work with CONFIG_BOOTDELAY. None are required.
812		CONFIG_BOOT_RETRY_TIME
813		CONFIG_BOOT_RETRY_MIN
814		CONFIG_AUTOBOOT_KEYED
815		CONFIG_AUTOBOOT_PROMPT
816		CONFIG_AUTOBOOT_DELAY_STR
817		CONFIG_AUTOBOOT_STOP_STR
818		CONFIG_AUTOBOOT_DELAY_STR2
819		CONFIG_AUTOBOOT_STOP_STR2
820		CONFIG_ZERO_BOOTDELAY_CHECK
821		CONFIG_RESET_TO_RETRY
822
823- Autoboot Command:
824		CONFIG_BOOTCOMMAND
825		Only needed when CONFIG_BOOTDELAY is enabled;
826		define a command string that is automatically executed
827		when no character is read on the console interface
828		within "Boot Delay" after reset.
829
830		CONFIG_BOOTARGS
831		This can be used to pass arguments to the bootm
832		command. The value of CONFIG_BOOTARGS goes into the
833		environment value "bootargs".
834
835		CONFIG_RAMBOOT and CONFIG_NFSBOOT
836		The value of these goes into the environment as
837		"ramboot" and "nfsboot" respectively, and can be used
838		as a convenience, when switching between booting from
839		RAM and NFS.
840
841- Bootcount:
842		CONFIG_BOOTCOUNT_LIMIT
843		Implements a mechanism for detecting a repeating reboot
844		cycle, see:
845		http://www.denx.de/wiki/view/DULG/UBootBootCountLimit
846
847		CONFIG_BOOTCOUNT_ENV
848		If no softreset save registers are found on the hardware
849		"bootcount" is stored in the environment. To prevent a
850		saveenv on all reboots, the environment variable
851		"upgrade_available" is used. If "upgrade_available" is
852		0, "bootcount" is always 0, if "upgrade_available" is
853		1 "bootcount" is incremented in the environment.
854		So the Userspace Applikation must set the "upgrade_available"
855		and "bootcount" variable to 0, if a boot was successfully.
856
857- Pre-Boot Commands:
858		CONFIG_PREBOOT
859
860		When this option is #defined, the existence of the
861		environment variable "preboot" will be checked
862		immediately before starting the CONFIG_BOOTDELAY
863		countdown and/or running the auto-boot command resp.
864		entering interactive mode.
865
866		This feature is especially useful when "preboot" is
867		automatically generated or modified. For an example
868		see the LWMON board specific code: here "preboot" is
869		modified when the user holds down a certain
870		combination of keys on the (special) keyboard when
871		booting the systems
872
873- Serial Download Echo Mode:
874		CONFIG_LOADS_ECHO
875		If defined to 1, all characters received during a
876		serial download (using the "loads" command) are
877		echoed back. This might be needed by some terminal
878		emulations (like "cu"), but may as well just take
879		time on others. This setting #define's the initial
880		value of the "loads_echo" environment variable.
881
882- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
883		CONFIG_KGDB_BAUDRATE
884		Select one of the baudrates listed in
885		CONFIG_SYS_BAUDRATE_TABLE, see below.
886
887- Monitor Functions:
888		Monitor commands can be included or excluded
889		from the build by using the #include files
890		<config_cmd_all.h> and #undef'ing unwanted
891		commands, or using <config_cmd_default.h>
892		and augmenting with additional #define's
893		for wanted commands.
894
895		The default command configuration includes all commands
896		except those marked below with a "*".
897
898		CONFIG_CMD_ASKENV	* ask for env variable
899		CONFIG_CMD_BDI		  bdinfo
900		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
901		CONFIG_CMD_BMP		* BMP support
902		CONFIG_CMD_BSP		* Board specific commands
903		CONFIG_CMD_BOOTD	  bootd
904		CONFIG_CMD_CACHE	* icache, dcache
905		CONFIG_CMD_CLK   	* clock command support
906		CONFIG_CMD_CONSOLE	  coninfo
907		CONFIG_CMD_CRC32	* crc32
908		CONFIG_CMD_DATE		* support for RTC, date/time...
909		CONFIG_CMD_DHCP		* DHCP support
910		CONFIG_CMD_DIAG		* Diagnostics
911		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
912		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
913		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
914		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
915		CONFIG_CMD_DTT		* Digital Therm and Thermostat
916		CONFIG_CMD_ECHO		  echo arguments
917		CONFIG_CMD_EDITENV	  edit env variable
918		CONFIG_CMD_EEPROM	* EEPROM read/write support
919		CONFIG_CMD_ELF		* bootelf, bootvx
920		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
921		CONFIG_CMD_ENV_FLAGS	* display details about env flags
922		CONFIG_CMD_ENV_EXISTS	* check existence of env variable
923		CONFIG_CMD_EXPORTENV	* export the environment
924		CONFIG_CMD_EXT2		* ext2 command support
925		CONFIG_CMD_EXT4		* ext4 command support
926		CONFIG_CMD_FS_GENERIC	* filesystem commands (e.g. load, ls)
927					  that work for multiple fs types
928		CONFIG_CMD_SAVEENV	  saveenv
929		CONFIG_CMD_FDC		* Floppy Disk Support
930		CONFIG_CMD_FAT		* FAT command support
931		CONFIG_CMD_FDOS		* Dos diskette Support
932		CONFIG_CMD_FLASH	  flinfo, erase, protect
933		CONFIG_CMD_FPGA		  FPGA device initialization support
934		CONFIG_CMD_FUSE		* Device fuse support
935		CONFIG_CMD_GETTIME	* Get time since boot
936		CONFIG_CMD_GO		* the 'go' command (exec code)
937		CONFIG_CMD_GREPENV	* search environment
938		CONFIG_CMD_HASH		* calculate hash / digest
939		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
940		CONFIG_CMD_I2C		* I2C serial bus support
941		CONFIG_CMD_IDE		* IDE harddisk support
942		CONFIG_CMD_IMI		  iminfo
943		CONFIG_CMD_IMLS		  List all images found in NOR flash
944		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash
945		CONFIG_CMD_IMMAP	* IMMR dump support
946		CONFIG_CMD_IMPORTENV	* import an environment
947		CONFIG_CMD_INI		* import data from an ini file into the env
948		CONFIG_CMD_IRQ		* irqinfo
949		CONFIG_CMD_ITEST	  Integer/string test of 2 values
950		CONFIG_CMD_JFFS2	* JFFS2 Support
951		CONFIG_CMD_KGDB		* kgdb
952		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)
953		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
954					  (169.254.*.*)
955		CONFIG_CMD_LOADB	  loadb
956		CONFIG_CMD_LOADS	  loads
957		CONFIG_CMD_MD5SUM	* print md5 message digest
958					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
959		CONFIG_CMD_MEMINFO	* Display detailed memory information
960		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
961					  loop, loopw
962		CONFIG_CMD_MEMTEST	* mtest
963		CONFIG_CMD_MISC		  Misc functions like sleep etc
964		CONFIG_CMD_MMC		* MMC memory mapped support
965		CONFIG_CMD_MII		* MII utility commands
966		CONFIG_CMD_MTDPARTS	* MTD partition support
967		CONFIG_CMD_NAND		* NAND support
968		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
969		CONFIG_CMD_NFS		  NFS support
970		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
971		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
972		CONFIG_CMD_PCI		* pciinfo
973		CONFIG_CMD_PCMCIA		* PCMCIA support
974		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
975					  host
976		CONFIG_CMD_PORTIO	* Port I/O
977		CONFIG_CMD_READ		* Read raw data from partition
978		CONFIG_CMD_REGINFO	* Register dump
979		CONFIG_CMD_RUN		  run command in env variable
980		CONFIG_CMD_SANDBOX	* sb command to access sandbox features
981		CONFIG_CMD_SAVES	* save S record dump
982		CONFIG_CMD_SCSI		* SCSI Support
983		CONFIG_CMD_SDRAM	* print SDRAM configuration information
984					  (requires CONFIG_CMD_I2C)
985		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
986					  (4xx only)
987		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
988		CONFIG_CMD_SHA1SUM	* print sha1 memory digest
989					  (requires CONFIG_CMD_MEMORY)
990		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x
991		CONFIG_CMD_SOURCE	  "source" command Support
992		CONFIG_CMD_SPI		* SPI serial bus support
993		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
994		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
995		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
996		CONFIG_CMD_TIMER	* access to the system tick timer
997		CONFIG_CMD_USB		* USB support
998		CONFIG_CMD_CDP		* Cisco Discover Protocol support
999		CONFIG_CMD_MFSL		* Microblaze FSL support
1000		CONFIG_CMD_XIMG		  Load part of Multi Image
1001
1002
1003		EXAMPLE: If you want all functions except of network
1004		support you can write:
1005
1006		#include "config_cmd_all.h"
1007		#undef CONFIG_CMD_NET
1008
1009	Other Commands:
1010		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
1011
1012	Note:	Don't enable the "icache" and "dcache" commands
1013		(configuration option CONFIG_CMD_CACHE) unless you know
1014		what you (and your U-Boot users) are doing. Data
1015		cache cannot be enabled on systems like the 8xx or
1016		8260 (where accesses to the IMMR region must be
1017		uncached), and it cannot be disabled on all other
1018		systems where we (mis-) use the data cache to hold an
1019		initial stack and some data.
1020
1021
1022		XXX - this list needs to get updated!
1023
1024- Regular expression support:
1025		CONFIG_REGEX
1026		If this variable is defined, U-Boot is linked against
1027		the SLRE (Super Light Regular Expression) library,
1028		which adds regex support to some commands, as for
1029		example "env grep" and "setexpr".
1030
1031- Device tree:
1032		CONFIG_OF_CONTROL
1033		If this variable is defined, U-Boot will use a device tree
1034		to configure its devices, instead of relying on statically
1035		compiled #defines in the board file. This option is
1036		experimental and only available on a few boards. The device
1037		tree is available in the global data as gd->fdt_blob.
1038
1039		U-Boot needs to get its device tree from somewhere. This can
1040		be done using one of the two options below:
1041
1042		CONFIG_OF_EMBED
1043		If this variable is defined, U-Boot will embed a device tree
1044		binary in its image. This device tree file should be in the
1045		board directory and called <soc>-<board>.dts. The binary file
1046		is then picked up in board_init_f() and made available through
1047		the global data structure as gd->blob.
1048
1049		CONFIG_OF_SEPARATE
1050		If this variable is defined, U-Boot will build a device tree
1051		binary. It will be called u-boot.dtb. Architecture-specific
1052		code will locate it at run-time. Generally this works by:
1053
1054			cat u-boot.bin u-boot.dtb >image.bin
1055
1056		and in fact, U-Boot does this for you, creating a file called
1057		u-boot-dtb.bin which is useful in the common case. You can
1058		still use the individual files if you need something more
1059		exotic.
1060
1061- Watchdog:
1062		CONFIG_WATCHDOG
1063		If this variable is defined, it enables watchdog
1064		support for the SoC. There must be support in the SoC
1065		specific code for a watchdog. For the 8xx and 8260
1066		CPUs, the SIU Watchdog feature is enabled in the SYPCR
1067		register.  When supported for a specific SoC is
1068		available, then no further board specific code should
1069		be needed to use it.
1070
1071		CONFIG_HW_WATCHDOG
1072		When using a watchdog circuitry external to the used
1073		SoC, then define this variable and provide board
1074		specific code for the "hw_watchdog_reset" function.
1075
1076- U-Boot Version:
1077		CONFIG_VERSION_VARIABLE
1078		If this variable is defined, an environment variable
1079		named "ver" is created by U-Boot showing the U-Boot
1080		version as printed by the "version" command.
1081		Any change to this variable will be reverted at the
1082		next reset.
1083
1084- Real-Time Clock:
1085
1086		When CONFIG_CMD_DATE is selected, the type of the RTC
1087		has to be selected, too. Define exactly one of the
1088		following options:
1089
1090		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
1091		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
1092		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
1093		CONFIG_RTC_MC146818	- use MC146818 RTC
1094		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
1095		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
1096		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
1097		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
1098		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
1099		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
1100		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
1101		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
1102					  RV3029 RTC.
1103
1104		Note that if the RTC uses I2C, then the I2C interface
1105		must also be configured. See I2C Support, below.
1106
1107- GPIO Support:
1108		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
1109
1110		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1111		chip-ngpio pairs that tell the PCA953X driver the number of
1112		pins supported by a particular chip.
1113
1114		Note that if the GPIO device uses I2C, then the I2C interface
1115		must also be configured. See I2C Support, below.
1116
1117- Timestamp Support:
1118
1119		When CONFIG_TIMESTAMP is selected, the timestamp
1120		(date and time) of an image is printed by image
1121		commands like bootm or iminfo. This option is
1122		automatically enabled when you select CONFIG_CMD_DATE .
1123
1124- Partition Labels (disklabels) Supported:
1125		Zero or more of the following:
1126		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1127		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1128				       Intel architecture, USB sticks, etc.
1129		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1130		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1131				       bootloader.  Note 2TB partition limit; see
1132				       disk/part_efi.c
1133		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1134
1135		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1136		CONFIG_CMD_SCSI) you must configure support for at
1137		least one non-MTD partition type as well.
1138
1139- IDE Reset method:
1140		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1141		board configurations files but used nowhere!
1142
1143		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1144		be performed by calling the function
1145			ide_set_reset(int reset)
1146		which has to be defined in a board specific file
1147
1148- ATAPI Support:
1149		CONFIG_ATAPI
1150
1151		Set this to enable ATAPI support.
1152
1153- LBA48 Support
1154		CONFIG_LBA48
1155
1156		Set this to enable support for disks larger than 137GB
1157		Also look at CONFIG_SYS_64BIT_LBA.
1158		Whithout these , LBA48 support uses 32bit variables and will 'only'
1159		support disks up to 2.1TB.
1160
1161		CONFIG_SYS_64BIT_LBA:
1162			When enabled, makes the IDE subsystem use 64bit sector addresses.
1163			Default is 32bit.
1164
1165- SCSI Support:
1166		At the moment only there is only support for the
1167		SYM53C8XX SCSI controller; define
1168		CONFIG_SCSI_SYM53C8XX to enable it.
1169
1170		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1171		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1172		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1173		maximum numbers of LUNs, SCSI ID's and target
1174		devices.
1175		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1176
1177		The environment variable 'scsidevs' is set to the number of
1178		SCSI devices found during the last scan.
1179
1180- NETWORK Support (PCI):
1181		CONFIG_E1000
1182		Support for Intel 8254x/8257x gigabit chips.
1183
1184		CONFIG_E1000_SPI
1185		Utility code for direct access to the SPI bus on Intel 8257x.
1186		This does not do anything useful unless you set at least one
1187		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1188
1189		CONFIG_E1000_SPI_GENERIC
1190		Allow generic access to the SPI bus on the Intel 8257x, for
1191		example with the "sspi" command.
1192
1193		CONFIG_CMD_E1000
1194		Management command for E1000 devices.  When used on devices
1195		with SPI support you can reprogram the EEPROM from U-Boot.
1196
1197		CONFIG_E1000_FALLBACK_MAC
1198		default MAC for empty EEPROM after production.
1199
1200		CONFIG_EEPRO100
1201		Support for Intel 82557/82559/82559ER chips.
1202		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1203		write routine for first time initialisation.
1204
1205		CONFIG_TULIP
1206		Support for Digital 2114x chips.
1207		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1208		modem chip initialisation (KS8761/QS6611).
1209
1210		CONFIG_NATSEMI
1211		Support for National dp83815 chips.
1212
1213		CONFIG_NS8382X
1214		Support for National dp8382[01] gigabit chips.
1215
1216- NETWORK Support (other):
1217
1218		CONFIG_DRIVER_AT91EMAC
1219		Support for AT91RM9200 EMAC.
1220
1221			CONFIG_RMII
1222			Define this to use reduced MII inteface
1223
1224			CONFIG_DRIVER_AT91EMAC_QUIET
1225			If this defined, the driver is quiet.
1226			The driver doen't show link status messages.
1227
1228		CONFIG_CALXEDA_XGMAC
1229		Support for the Calxeda XGMAC device
1230
1231		CONFIG_LAN91C96
1232		Support for SMSC's LAN91C96 chips.
1233
1234			CONFIG_LAN91C96_BASE
1235			Define this to hold the physical address
1236			of the LAN91C96's I/O space
1237
1238			CONFIG_LAN91C96_USE_32_BIT
1239			Define this to enable 32 bit addressing
1240
1241		CONFIG_SMC91111
1242		Support for SMSC's LAN91C111 chip
1243
1244			CONFIG_SMC91111_BASE
1245			Define this to hold the physical address
1246			of the device (I/O space)
1247
1248			CONFIG_SMC_USE_32_BIT
1249			Define this if data bus is 32 bits
1250
1251			CONFIG_SMC_USE_IOFUNCS
1252			Define this to use i/o functions instead of macros
1253			(some hardware wont work with macros)
1254
1255		CONFIG_DRIVER_TI_EMAC
1256		Support for davinci emac
1257
1258			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1259			Define this if you have more then 3 PHYs.
1260
1261		CONFIG_FTGMAC100
1262		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1263
1264			CONFIG_FTGMAC100_EGIGA
1265			Define this to use GE link update with gigabit PHY.
1266			Define this if FTGMAC100 is connected to gigabit PHY.
1267			If your system has 10/100 PHY only, it might not occur
1268			wrong behavior. Because PHY usually return timeout or
1269			useless data when polling gigabit status and gigabit
1270			control registers. This behavior won't affect the
1271			correctnessof 10/100 link speed update.
1272
1273		CONFIG_SMC911X
1274		Support for SMSC's LAN911x and LAN921x chips
1275
1276			CONFIG_SMC911X_BASE
1277			Define this to hold the physical address
1278			of the device (I/O space)
1279
1280			CONFIG_SMC911X_32_BIT
1281			Define this if data bus is 32 bits
1282
1283			CONFIG_SMC911X_16_BIT
1284			Define this if data bus is 16 bits. If your processor
1285			automatically converts one 32 bit word to two 16 bit
1286			words you may also try CONFIG_SMC911X_32_BIT.
1287
1288		CONFIG_SH_ETHER
1289		Support for Renesas on-chip Ethernet controller
1290
1291			CONFIG_SH_ETHER_USE_PORT
1292			Define the number of ports to be used
1293
1294			CONFIG_SH_ETHER_PHY_ADDR
1295			Define the ETH PHY's address
1296
1297			CONFIG_SH_ETHER_CACHE_WRITEBACK
1298			If this option is set, the driver enables cache flush.
1299
1300- TPM Support:
1301		CONFIG_TPM
1302		Support TPM devices.
1303
1304		CONFIG_TPM_TIS_I2C
1305		Support for i2c bus TPM devices. Only one device
1306		per system is supported at this time.
1307
1308			CONFIG_TPM_TIS_I2C_BUS_NUMBER
1309			Define the the i2c bus number for the TPM device
1310
1311			CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS
1312			Define the TPM's address on the i2c bus
1313
1314			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1315			Define the burst count bytes upper limit
1316
1317		CONFIG_TPM_ATMEL_TWI
1318		Support for Atmel TWI TPM device. Requires I2C support.
1319
1320		CONFIG_TPM_TIS_LPC
1321		Support for generic parallel port TPM devices. Only one device
1322		per system is supported at this time.
1323
1324			CONFIG_TPM_TIS_BASE_ADDRESS
1325			Base address where the generic TPM device is mapped
1326			to. Contemporary x86 systems usually map it at
1327			0xfed40000.
1328
1329		CONFIG_CMD_TPM
1330		Add tpm monitor functions.
1331		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1332		provides monitor access to authorized functions.
1333
1334		CONFIG_TPM
1335		Define this to enable the TPM support library which provides
1336		functional interfaces to some TPM commands.
1337		Requires support for a TPM device.
1338
1339		CONFIG_TPM_AUTH_SESSIONS
1340		Define this to enable authorized functions in the TPM library.
1341		Requires CONFIG_TPM and CONFIG_SHA1.
1342
1343- USB Support:
1344		At the moment only the UHCI host controller is
1345		supported (PIP405, MIP405, MPC5200); define
1346		CONFIG_USB_UHCI to enable it.
1347		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1348		and define CONFIG_USB_STORAGE to enable the USB
1349		storage devices.
1350		Note:
1351		Supported are USB Keyboards and USB Floppy drives
1352		(TEAC FD-05PUB).
1353		MPC5200 USB requires additional defines:
1354			CONFIG_USB_CLOCK
1355				for 528 MHz Clock: 0x0001bbbb
1356			CONFIG_PSC3_USB
1357				for USB on PSC3
1358			CONFIG_USB_CONFIG
1359				for differential drivers: 0x00001000
1360				for single ended drivers: 0x00005000
1361				for differential drivers on PSC3: 0x00000100
1362				for single ended drivers on PSC3: 0x00004100
1363			CONFIG_SYS_USB_EVENT_POLL
1364				May be defined to allow interrupt polling
1365				instead of using asynchronous interrupts
1366
1367		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1368		txfilltuning field in the EHCI controller on reset.
1369
1370		CONFIG_USB_HUB_MIN_POWER_ON_DELAY defines the minimum
1371		interval for usb hub power-on delay.(minimum 100msec)
1372
1373- USB Device:
1374		Define the below if you wish to use the USB console.
1375		Once firmware is rebuilt from a serial console issue the
1376		command "setenv stdin usbtty; setenv stdout usbtty" and
1377		attach your USB cable. The Unix command "dmesg" should print
1378		it has found a new device. The environment variable usbtty
1379		can be set to gserial or cdc_acm to enable your device to
1380		appear to a USB host as a Linux gserial device or a
1381		Common Device Class Abstract Control Model serial device.
1382		If you select usbtty = gserial you should be able to enumerate
1383		a Linux host by
1384		# modprobe usbserial vendor=0xVendorID product=0xProductID
1385		else if using cdc_acm, simply setting the environment
1386		variable usbtty to be cdc_acm should suffice. The following
1387		might be defined in YourBoardName.h
1388
1389			CONFIG_USB_DEVICE
1390			Define this to build a UDC device
1391
1392			CONFIG_USB_TTY
1393			Define this to have a tty type of device available to
1394			talk to the UDC device
1395
1396			CONFIG_USBD_HS
1397			Define this to enable the high speed support for usb
1398			device and usbtty. If this feature is enabled, a routine
1399			int is_usbd_high_speed(void)
1400			also needs to be defined by the driver to dynamically poll
1401			whether the enumeration has succeded at high speed or full
1402			speed.
1403
1404			CONFIG_SYS_CONSOLE_IS_IN_ENV
1405			Define this if you want stdin, stdout &/or stderr to
1406			be set to usbtty.
1407
1408			mpc8xx:
1409				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1410				Derive USB clock from external clock "blah"
1411				- CONFIG_SYS_USB_EXTC_CLK 0x02
1412
1413				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1414				Derive USB clock from brgclk
1415				- CONFIG_SYS_USB_BRG_CLK 0x04
1416
1417		If you have a USB-IF assigned VendorID then you may wish to
1418		define your own vendor specific values either in BoardName.h
1419		or directly in usbd_vendor_info.h. If you don't define
1420		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1421		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1422		should pretend to be a Linux device to it's target host.
1423
1424			CONFIG_USBD_MANUFACTURER
1425			Define this string as the name of your company for
1426			- CONFIG_USBD_MANUFACTURER "my company"
1427
1428			CONFIG_USBD_PRODUCT_NAME
1429			Define this string as the name of your product
1430			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1431
1432			CONFIG_USBD_VENDORID
1433			Define this as your assigned Vendor ID from the USB
1434			Implementors Forum. This *must* be a genuine Vendor ID
1435			to avoid polluting the USB namespace.
1436			- CONFIG_USBD_VENDORID 0xFFFF
1437
1438			CONFIG_USBD_PRODUCTID
1439			Define this as the unique Product ID
1440			for your device
1441			- CONFIG_USBD_PRODUCTID 0xFFFF
1442
1443		Some USB device drivers may need to check USB cable attachment.
1444		In this case you can enable following config in BoardName.h:
1445			CONFIG_USB_CABLE_CHECK
1446			This enables function definition:
1447			- usb_cable_connected() in include/usb.h
1448			Implementation of this function is board-specific.
1449
1450- ULPI Layer Support:
1451		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1452		the generic ULPI layer. The generic layer accesses the ULPI PHY
1453		via the platform viewport, so you need both the genric layer and
1454		the viewport enabled. Currently only Chipidea/ARC based
1455		viewport is supported.
1456		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1457		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1458		If your ULPI phy needs a different reference clock than the
1459		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1460		the appropriate value in Hz.
1461
1462- MMC Support:
1463		The MMC controller on the Intel PXA is supported. To
1464		enable this define CONFIG_MMC. The MMC can be
1465		accessed from the boot prompt by mapping the device
1466		to physical memory similar to flash. Command line is
1467		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1468		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1469
1470		CONFIG_SH_MMCIF
1471		Support for Renesas on-chip MMCIF controller
1472
1473			CONFIG_SH_MMCIF_ADDR
1474			Define the base address of MMCIF registers
1475
1476			CONFIG_SH_MMCIF_CLK
1477			Define the clock frequency for MMCIF
1478
1479- USB Device Firmware Update (DFU) class support:
1480		CONFIG_DFU_FUNCTION
1481		This enables the USB portion of the DFU USB class
1482
1483		CONFIG_CMD_DFU
1484		This enables the command "dfu" which is used to have
1485		U-Boot create a DFU class device via USB.  This command
1486		requires that the "dfu_alt_info" environment variable be
1487		set and define the alt settings to expose to the host.
1488
1489		CONFIG_DFU_MMC
1490		This enables support for exposing (e)MMC devices via DFU.
1491
1492		CONFIG_DFU_NAND
1493		This enables support for exposing NAND devices via DFU.
1494
1495		CONFIG_DFU_RAM
1496		This enables support for exposing RAM via DFU.
1497		Note: DFU spec refer to non-volatile memory usage, but
1498		allow usages beyond the scope of spec - here RAM usage,
1499		one that would help mostly the developer.
1500
1501		CONFIG_SYS_DFU_DATA_BUF_SIZE
1502		Dfu transfer uses a buffer before writing data to the
1503		raw storage device. Make the size (in bytes) of this buffer
1504		configurable. The size of this buffer is also configurable
1505		through the "dfu_bufsiz" environment variable.
1506
1507		CONFIG_SYS_DFU_MAX_FILE_SIZE
1508		When updating files rather than the raw storage device,
1509		we use a static buffer to copy the file into and then write
1510		the buffer once we've been given the whole file.  Define
1511		this to the maximum filesize (in bytes) for the buffer.
1512		Default is 4 MiB if undefined.
1513
1514- Journaling Flash filesystem support:
1515		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1516		CONFIG_JFFS2_NAND_DEV
1517		Define these for a default partition on a NAND device
1518
1519		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1520		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1521		Define these for a default partition on a NOR device
1522
1523		CONFIG_SYS_JFFS_CUSTOM_PART
1524		Define this to create an own partition. You have to provide a
1525		function struct part_info* jffs2_part_info(int part_num)
1526
1527		If you define only one JFFS2 partition you may also want to
1528		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1529		to disable the command chpart. This is the default when you
1530		have not defined a custom partition
1531
1532- FAT(File Allocation Table) filesystem write function support:
1533		CONFIG_FAT_WRITE
1534
1535		Define this to enable support for saving memory data as a
1536		file in FAT formatted partition.
1537
1538		This will also enable the command "fatwrite" enabling the
1539		user to write files to FAT.
1540
1541CBFS (Coreboot Filesystem) support
1542		CONFIG_CMD_CBFS
1543
1544		Define this to enable support for reading from a Coreboot
1545		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1546		and cbfsload.
1547
1548- Keyboard Support:
1549		CONFIG_ISA_KEYBOARD
1550
1551		Define this to enable standard (PC-Style) keyboard
1552		support
1553
1554		CONFIG_I8042_KBD
1555		Standard PC keyboard driver with US (is default) and
1556		GERMAN key layout (switch via environment 'keymap=de') support.
1557		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1558		for cfb_console. Supports cursor blinking.
1559
1560		CONFIG_CROS_EC_KEYB
1561		Enables a Chrome OS keyboard using the CROS_EC interface.
1562		This uses CROS_EC to communicate with a second microcontroller
1563		which provides key scans on request.
1564
1565- Video support:
1566		CONFIG_VIDEO
1567
1568		Define this to enable video support (for output to
1569		video).
1570
1571		CONFIG_VIDEO_CT69000
1572
1573		Enable Chips & Technologies 69000 Video chip
1574
1575		CONFIG_VIDEO_SMI_LYNXEM
1576		Enable Silicon Motion SMI 712/710/810 Video chip. The
1577		video output is selected via environment 'videoout'
1578		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1579		assumed.
1580
1581		For the CT69000 and SMI_LYNXEM drivers, videomode is
1582		selected via environment 'videomode'. Two different ways
1583		are possible:
1584		- "videomode=num"   'num' is a standard LiLo mode numbers.
1585		Following standard modes are supported	(* is default):
1586
1587		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1588		-------------+---------------------------------------------
1589		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1590		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1591		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1592		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1593		-------------+---------------------------------------------
1594		(i.e. setenv videomode 317; saveenv; reset;)
1595
1596		- "videomode=bootargs" all the video parameters are parsed
1597		from the bootargs. (See drivers/video/videomodes.c)
1598
1599
1600		CONFIG_VIDEO_SED13806
1601		Enable Epson SED13806 driver. This driver supports 8bpp
1602		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1603		or CONFIG_VIDEO_SED13806_16BPP
1604
1605		CONFIG_FSL_DIU_FB
1606		Enable the Freescale DIU video driver.	Reference boards for
1607		SOCs that have a DIU should define this macro to enable DIU
1608		support, and should also define these other macros:
1609
1610			CONFIG_SYS_DIU_ADDR
1611			CONFIG_VIDEO
1612			CONFIG_CMD_BMP
1613			CONFIG_CFB_CONSOLE
1614			CONFIG_VIDEO_SW_CURSOR
1615			CONFIG_VGA_AS_SINGLE_DEVICE
1616			CONFIG_VIDEO_LOGO
1617			CONFIG_VIDEO_BMP_LOGO
1618
1619		The DIU driver will look for the 'video-mode' environment
1620		variable, and if defined, enable the DIU as a console during
1621		boot.  See the documentation file README.video for a
1622		description of this variable.
1623
1624		CONFIG_VIDEO_VGA
1625
1626		Enable the VGA video / BIOS for x86. The alternative if you
1627		are using coreboot is to use the coreboot frame buffer
1628		driver.
1629
1630
1631- Keyboard Support:
1632		CONFIG_KEYBOARD
1633
1634		Define this to enable a custom keyboard support.
1635		This simply calls drv_keyboard_init() which must be
1636		defined in your board-specific files.
1637		The only board using this so far is RBC823.
1638
1639- LCD Support:	CONFIG_LCD
1640
1641		Define this to enable LCD support (for output to LCD
1642		display); also select one of the supported displays
1643		by defining one of these:
1644
1645		CONFIG_ATMEL_LCD:
1646
1647			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1648
1649		CONFIG_NEC_NL6448AC33:
1650
1651			NEC NL6448AC33-18. Active, color, single scan.
1652
1653		CONFIG_NEC_NL6448BC20
1654
1655			NEC NL6448BC20-08. 6.5", 640x480.
1656			Active, color, single scan.
1657
1658		CONFIG_NEC_NL6448BC33_54
1659
1660			NEC NL6448BC33-54. 10.4", 640x480.
1661			Active, color, single scan.
1662
1663		CONFIG_SHARP_16x9
1664
1665			Sharp 320x240. Active, color, single scan.
1666			It isn't 16x9, and I am not sure what it is.
1667
1668		CONFIG_SHARP_LQ64D341
1669
1670			Sharp LQ64D341 display, 640x480.
1671			Active, color, single scan.
1672
1673		CONFIG_HLD1045
1674
1675			HLD1045 display, 640x480.
1676			Active, color, single scan.
1677
1678		CONFIG_OPTREX_BW
1679
1680			Optrex	 CBL50840-2 NF-FW 99 22 M5
1681			or
1682			Hitachi	 LMG6912RPFC-00T
1683			or
1684			Hitachi	 SP14Q002
1685
1686			320x240. Black & white.
1687
1688		Normally display is black on white background; define
1689		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1690
1691		CONFIG_LCD_ALIGNMENT
1692
1693		Normally the LCD is page-aligned (tyically 4KB). If this is
1694		defined then the LCD will be aligned to this value instead.
1695		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1696		here, since it is cheaper to change data cache settings on
1697		a per-section basis.
1698
1699		CONFIG_CONSOLE_SCROLL_LINES
1700
1701		When the console need to be scrolled, this is the number of
1702		lines to scroll by. It defaults to 1. Increasing this makes
1703		the console jump but can help speed up operation when scrolling
1704		is slow.
1705
1706		CONFIG_LCD_BMP_RLE8
1707
1708		Support drawing of RLE8-compressed bitmaps on the LCD.
1709
1710		CONFIG_I2C_EDID
1711
1712		Enables an 'i2c edid' command which can read EDID
1713		information over I2C from an attached LCD display.
1714
1715- Splash Screen Support: CONFIG_SPLASH_SCREEN
1716
1717		If this option is set, the environment is checked for
1718		a variable "splashimage". If found, the usual display
1719		of logo, copyright and system information on the LCD
1720		is suppressed and the BMP image at the address
1721		specified in "splashimage" is loaded instead. The
1722		console is redirected to the "nulldev", too. This
1723		allows for a "silent" boot where a splash screen is
1724		loaded very quickly after power-on.
1725
1726		CONFIG_SPLASHIMAGE_GUARD
1727
1728		If this option is set, then U-Boot will prevent the environment
1729		variable "splashimage" from being set to a problematic address
1730		(see README.displaying-bmps and README.arm-unaligned-accesses).
1731		This option is useful for targets where, due to alignment
1732		restrictions, an improperly aligned BMP image will cause a data
1733		abort. If you think you will not have problems with unaligned
1734		accesses (for example because your toolchain prevents them)
1735		there is no need to set this option.
1736
1737		CONFIG_SPLASH_SCREEN_ALIGN
1738
1739		If this option is set the splash image can be freely positioned
1740		on the screen. Environment variable "splashpos" specifies the
1741		position as "x,y". If a positive number is given it is used as
1742		number of pixel from left/top. If a negative number is given it
1743		is used as number of pixel from right/bottom. You can also
1744		specify 'm' for centering the image.
1745
1746		Example:
1747		setenv splashpos m,m
1748			=> image at center of screen
1749
1750		setenv splashpos 30,20
1751			=> image at x = 30 and y = 20
1752
1753		setenv splashpos -10,m
1754			=> vertically centered image
1755			   at x = dspWidth - bmpWidth - 9
1756
1757- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1758
1759		If this option is set, additionally to standard BMP
1760		images, gzipped BMP images can be displayed via the
1761		splashscreen support or the bmp command.
1762
1763- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1764
1765		If this option is set, 8-bit RLE compressed BMP images
1766		can be displayed via the splashscreen support or the
1767		bmp command.
1768
1769- Do compresssing for memory range:
1770		CONFIG_CMD_ZIP
1771
1772		If this option is set, it would use zlib deflate method
1773		to compress the specified memory at its best effort.
1774
1775- Compression support:
1776		CONFIG_GZIP
1777
1778		Enabled by default to support gzip compressed images.
1779
1780		CONFIG_BZIP2
1781
1782		If this option is set, support for bzip2 compressed
1783		images is included. If not, only uncompressed and gzip
1784		compressed images are supported.
1785
1786		NOTE: the bzip2 algorithm requires a lot of RAM, so
1787		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1788		be at least 4MB.
1789
1790		CONFIG_LZMA
1791
1792		If this option is set, support for lzma compressed
1793		images is included.
1794
1795		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1796		requires an amount of dynamic memory that is given by the
1797		formula:
1798
1799			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1800
1801		Where lc and lp stand for, respectively, Literal context bits
1802		and Literal pos bits.
1803
1804		This value is upper-bounded by 14MB in the worst case. Anyway,
1805		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1806		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1807		a very small buffer.
1808
1809		Use the lzmainfo tool to determinate the lc and lp values and
1810		then calculate the amount of needed dynamic memory (ensuring
1811		the appropriate CONFIG_SYS_MALLOC_LEN value).
1812
1813		CONFIG_LZO
1814
1815		If this option is set, support for LZO compressed images
1816		is included.
1817
1818- MII/PHY support:
1819		CONFIG_PHY_ADDR
1820
1821		The address of PHY on MII bus.
1822
1823		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1824
1825		The clock frequency of the MII bus
1826
1827		CONFIG_PHY_GIGE
1828
1829		If this option is set, support for speed/duplex
1830		detection of gigabit PHY is included.
1831
1832		CONFIG_PHY_RESET_DELAY
1833
1834		Some PHY like Intel LXT971A need extra delay after
1835		reset before any MII register access is possible.
1836		For such PHY, set this option to the usec delay
1837		required. (minimum 300usec for LXT971A)
1838
1839		CONFIG_PHY_CMD_DELAY (ppc4xx)
1840
1841		Some PHY like Intel LXT971A need extra delay after
1842		command issued before MII status register can be read
1843
1844- Ethernet address:
1845		CONFIG_ETHADDR
1846		CONFIG_ETH1ADDR
1847		CONFIG_ETH2ADDR
1848		CONFIG_ETH3ADDR
1849		CONFIG_ETH4ADDR
1850		CONFIG_ETH5ADDR
1851
1852		Define a default value for Ethernet address to use
1853		for the respective Ethernet interface, in case this
1854		is not determined automatically.
1855
1856- IP address:
1857		CONFIG_IPADDR
1858
1859		Define a default value for the IP address to use for
1860		the default Ethernet interface, in case this is not
1861		determined through e.g. bootp.
1862		(Environment variable "ipaddr")
1863
1864- Server IP address:
1865		CONFIG_SERVERIP
1866
1867		Defines a default value for the IP address of a TFTP
1868		server to contact when using the "tftboot" command.
1869		(Environment variable "serverip")
1870
1871		CONFIG_KEEP_SERVERADDR
1872
1873		Keeps the server's MAC address, in the env 'serveraddr'
1874		for passing to bootargs (like Linux's netconsole option)
1875
1876- Gateway IP address:
1877		CONFIG_GATEWAYIP
1878
1879		Defines a default value for the IP address of the
1880		default router where packets to other networks are
1881		sent to.
1882		(Environment variable "gatewayip")
1883
1884- Subnet mask:
1885		CONFIG_NETMASK
1886
1887		Defines a default value for the subnet mask (or
1888		routing prefix) which is used to determine if an IP
1889		address belongs to the local subnet or needs to be
1890		forwarded through a router.
1891		(Environment variable "netmask")
1892
1893- Multicast TFTP Mode:
1894		CONFIG_MCAST_TFTP
1895
1896		Defines whether you want to support multicast TFTP as per
1897		rfc-2090; for example to work with atftp.  Lets lots of targets
1898		tftp down the same boot image concurrently.  Note: the Ethernet
1899		driver in use must provide a function: mcast() to join/leave a
1900		multicast group.
1901
1902- BOOTP Recovery Mode:
1903		CONFIG_BOOTP_RANDOM_DELAY
1904
1905		If you have many targets in a network that try to
1906		boot using BOOTP, you may want to avoid that all
1907		systems send out BOOTP requests at precisely the same
1908		moment (which would happen for instance at recovery
1909		from a power failure, when all systems will try to
1910		boot, thus flooding the BOOTP server. Defining
1911		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1912		inserted before sending out BOOTP requests. The
1913		following delays are inserted then:
1914
1915		1st BOOTP request:	delay 0 ... 1 sec
1916		2nd BOOTP request:	delay 0 ... 2 sec
1917		3rd BOOTP request:	delay 0 ... 4 sec
1918		4th and following
1919		BOOTP requests:		delay 0 ... 8 sec
1920
1921- DHCP Advanced Options:
1922		You can fine tune the DHCP functionality by defining
1923		CONFIG_BOOTP_* symbols:
1924
1925		CONFIG_BOOTP_SUBNETMASK
1926		CONFIG_BOOTP_GATEWAY
1927		CONFIG_BOOTP_HOSTNAME
1928		CONFIG_BOOTP_NISDOMAIN
1929		CONFIG_BOOTP_BOOTPATH
1930		CONFIG_BOOTP_BOOTFILESIZE
1931		CONFIG_BOOTP_DNS
1932		CONFIG_BOOTP_DNS2
1933		CONFIG_BOOTP_SEND_HOSTNAME
1934		CONFIG_BOOTP_NTPSERVER
1935		CONFIG_BOOTP_TIMEOFFSET
1936		CONFIG_BOOTP_VENDOREX
1937		CONFIG_BOOTP_MAY_FAIL
1938
1939		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1940		environment variable, not the BOOTP server.
1941
1942		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1943		after the configured retry count, the call will fail
1944		instead of starting over.  This can be used to fail over
1945		to Link-local IP address configuration if the DHCP server
1946		is not available.
1947
1948		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1949		serverip from a DHCP server, it is possible that more
1950		than one DNS serverip is offered to the client.
1951		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1952		serverip will be stored in the additional environment
1953		variable "dnsip2". The first DNS serverip is always
1954		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1955		is defined.
1956
1957		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1958		to do a dynamic update of a DNS server. To do this, they
1959		need the hostname of the DHCP requester.
1960		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1961		of the "hostname" environment variable is passed as
1962		option 12 to the DHCP server.
1963
1964		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1965
1966		A 32bit value in microseconds for a delay between
1967		receiving a "DHCP Offer" and sending the "DHCP Request".
1968		This fixes a problem with certain DHCP servers that don't
1969		respond 100% of the time to a "DHCP request". E.g. On an
1970		AT91RM9200 processor running at 180MHz, this delay needed
1971		to be *at least* 15,000 usec before a Windows Server 2003
1972		DHCP server would reply 100% of the time. I recommend at
1973		least 50,000 usec to be safe. The alternative is to hope
1974		that one of the retries will be successful but note that
1975		the DHCP timeout and retry process takes a longer than
1976		this delay.
1977
1978 - Link-local IP address negotiation:
1979		Negotiate with other link-local clients on the local network
1980		for an address that doesn't require explicit configuration.
1981		This is especially useful if a DHCP server cannot be guaranteed
1982		to exist in all environments that the device must operate.
1983
1984		See doc/README.link-local for more information.
1985
1986 - CDP Options:
1987		CONFIG_CDP_DEVICE_ID
1988
1989		The device id used in CDP trigger frames.
1990
1991		CONFIG_CDP_DEVICE_ID_PREFIX
1992
1993		A two character string which is prefixed to the MAC address
1994		of the device.
1995
1996		CONFIG_CDP_PORT_ID
1997
1998		A printf format string which contains the ascii name of
1999		the port. Normally is set to "eth%d" which sets
2000		eth0 for the first Ethernet, eth1 for the second etc.
2001
2002		CONFIG_CDP_CAPABILITIES
2003
2004		A 32bit integer which indicates the device capabilities;
2005		0x00000010 for a normal host which does not forwards.
2006
2007		CONFIG_CDP_VERSION
2008
2009		An ascii string containing the version of the software.
2010
2011		CONFIG_CDP_PLATFORM
2012
2013		An ascii string containing the name of the platform.
2014
2015		CONFIG_CDP_TRIGGER
2016
2017		A 32bit integer sent on the trigger.
2018
2019		CONFIG_CDP_POWER_CONSUMPTION
2020
2021		A 16bit integer containing the power consumption of the
2022		device in .1 of milliwatts.
2023
2024		CONFIG_CDP_APPLIANCE_VLAN_TYPE
2025
2026		A byte containing the id of the VLAN.
2027
2028- Status LED:	CONFIG_STATUS_LED
2029
2030		Several configurations allow to display the current
2031		status using a LED. For instance, the LED will blink
2032		fast while running U-Boot code, stop blinking as
2033		soon as a reply to a BOOTP request was received, and
2034		start blinking slow once the Linux kernel is running
2035		(supported by a status LED driver in the Linux
2036		kernel). Defining CONFIG_STATUS_LED enables this
2037		feature in U-Boot.
2038
2039		Additional options:
2040
2041		CONFIG_GPIO_LED
2042		The status LED can be connected to a GPIO pin.
2043		In such cases, the gpio_led driver can be used as a
2044		status LED backend implementation. Define CONFIG_GPIO_LED
2045		to include the gpio_led driver in the U-Boot binary.
2046
2047		CONFIG_GPIO_LED_INVERTED_TABLE
2048		Some GPIO connected LEDs may have inverted polarity in which
2049		case the GPIO high value corresponds to LED off state and
2050		GPIO low value corresponds to LED on state.
2051		In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
2052		with a list of GPIO LEDs that have inverted polarity.
2053
2054- CAN Support:	CONFIG_CAN_DRIVER
2055
2056		Defining CONFIG_CAN_DRIVER enables CAN driver support
2057		on those systems that support this (optional)
2058		feature, like the TQM8xxL modules.
2059
2060- I2C Support:	CONFIG_SYS_I2C
2061
2062		This enable the NEW i2c subsystem, and will allow you to use
2063		i2c commands at the u-boot command line (as long as you set
2064		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
2065		based realtime clock chips or other i2c devices. See
2066		common/cmd_i2c.c for a description of the command line
2067		interface.
2068
2069		ported i2c driver to the new framework:
2070		- drivers/i2c/soft_i2c.c:
2071		  - activate first bus with CONFIG_SYS_I2C_SOFT define
2072		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
2073		    for defining speed and slave address
2074		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
2075		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
2076		    for defining speed and slave address
2077		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
2078		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
2079		    for defining speed and slave address
2080		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
2081		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
2082		    for defining speed and slave address
2083
2084		- drivers/i2c/fsl_i2c.c:
2085		  - activate i2c driver with CONFIG_SYS_I2C_FSL
2086		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
2087		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
2088		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
2089		    bus.
2090		  - If your board supports a second fsl i2c bus, define
2091		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
2092		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
2093		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
2094		    second bus.
2095
2096		- drivers/i2c/tegra_i2c.c:
2097		  - activate this driver with CONFIG_SYS_I2C_TEGRA
2098		  - This driver adds 4 i2c buses with a fix speed from
2099		    100000 and the slave addr 0!
2100
2101		- drivers/i2c/ppc4xx_i2c.c
2102		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
2103		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
2104		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
2105
2106		- drivers/i2c/i2c_mxc.c
2107		  - activate this driver with CONFIG_SYS_I2C_MXC
2108		  - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
2109		  - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
2110		  - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
2111		  - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
2112		  - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
2113		  - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
2114		If thoses defines are not set, default value is 100000
2115		for speed, and 0 for slave.
2116
2117		- drivers/i2c/rcar_i2c.c:
2118		  - activate this driver with CONFIG_SYS_I2C_RCAR
2119		  - This driver adds 4 i2c buses
2120
2121		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
2122		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
2123		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
2124		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
2125		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
2126		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
2127		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
2128		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
2129		  - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
2130
2131		- drivers/i2c/sh_i2c.c:
2132		  - activate this driver with CONFIG_SYS_I2C_SH
2133		  - This driver adds from 2 to 5 i2c buses
2134
2135		  - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
2136		  - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
2137		  - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
2138		  - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
2139		  - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
2140		  - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
2141		  - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
2142		  - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
2143		  - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
2144		  - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
2145		  - CONFIG_SYS_I2C_SH_BASE5 for setting the register channel 5
2146		  - CONFIG_SYS_I2C_SH_SPEED5 for for the speed channel 5
2147		  - CONFIF_SYS_I2C_SH_NUM_CONTROLLERS for nummber of i2c buses
2148
2149		- drivers/i2c/omap24xx_i2c.c
2150		  - activate this driver with CONFIG_SYS_I2C_OMAP24XX
2151		  - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
2152		  - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
2153		  - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
2154		  - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
2155		  - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
2156		  - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
2157		  - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
2158		  - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
2159		  - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
2160		  - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
2161
2162		- drivers/i2c/zynq_i2c.c
2163		  - activate this driver with CONFIG_SYS_I2C_ZYNQ
2164		  - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
2165		  - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
2166
2167		- drivers/i2c/s3c24x0_i2c.c:
2168		  - activate this driver with CONFIG_SYS_I2C_S3C24X0
2169		  - This driver adds i2c buses (11 for Exynos5250, Exynos5420
2170		    9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
2171		    with a fix speed from 100000 and the slave addr 0!
2172
2173		additional defines:
2174
2175		CONFIG_SYS_NUM_I2C_BUSES
2176		Hold the number of i2c busses you want to use. If you
2177		don't use/have i2c muxes on your i2c bus, this
2178		is equal to CONFIG_SYS_NUM_I2C_ADAPTERS, and you can
2179		omit this define.
2180
2181		CONFIG_SYS_I2C_DIRECT_BUS
2182		define this, if you don't use i2c muxes on your hardware.
2183		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2184		omit this define.
2185
2186		CONFIG_SYS_I2C_MAX_HOPS
2187		define how many muxes are maximal consecutively connected
2188		on one i2c bus. If you not use i2c muxes, omit this
2189		define.
2190
2191		CONFIG_SYS_I2C_BUSES
2192		hold a list of busses you want to use, only used if
2193		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2194		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2195		CONFIG_SYS_NUM_I2C_BUSES = 9:
2196
2197		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
2198					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2199					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2200					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2201					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2202					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2203					{1, {I2C_NULL_HOP}}, \
2204					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2205					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2206					}
2207
2208		which defines
2209			bus 0 on adapter 0 without a mux
2210			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2211			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2212			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2213			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2214			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2215			bus 6 on adapter 1 without a mux
2216			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2217			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2218
2219		If you do not have i2c muxes on your board, omit this define.
2220
2221- Legacy I2C Support:	CONFIG_HARD_I2C
2222
2223		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2224		provides the following compelling advantages:
2225
2226		- more than one i2c adapter is usable
2227		- approved multibus support
2228		- better i2c mux support
2229
2230		** Please consider updating your I2C driver now. **
2231
2232		These enable legacy I2C serial bus commands. Defining
2233		CONFIG_HARD_I2C will include the appropriate I2C driver
2234		for the selected CPU.
2235
2236		This will allow you to use i2c commands at the u-boot
2237		command line (as long as you set CONFIG_CMD_I2C in
2238		CONFIG_COMMANDS) and communicate with i2c based realtime
2239		clock chips. See common/cmd_i2c.c for a description of the
2240		command line interface.
2241
2242		CONFIG_HARD_I2C selects a hardware I2C controller.
2243
2244		There are several other quantities that must also be
2245		defined when you define CONFIG_HARD_I2C.
2246
2247		In both cases you will need to define CONFIG_SYS_I2C_SPEED
2248		to be the frequency (in Hz) at which you wish your i2c bus
2249		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2250		the CPU's i2c node address).
2251
2252		Now, the u-boot i2c code for the mpc8xx
2253		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2254		and so its address should therefore be cleared to 0 (See,
2255		eg, MPC823e User's Manual p.16-473). So, set
2256		CONFIG_SYS_I2C_SLAVE to 0.
2257
2258		CONFIG_SYS_I2C_INIT_MPC5XXX
2259
2260		When a board is reset during an i2c bus transfer
2261		chips might think that the current transfer is still
2262		in progress.  Reset the slave devices by sending start
2263		commands until the slave device responds.
2264
2265		That's all that's required for CONFIG_HARD_I2C.
2266
2267		If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2268		then the following macros need to be defined (examples are
2269		from include/configs/lwmon.h):
2270
2271		I2C_INIT
2272
2273		(Optional). Any commands necessary to enable the I2C
2274		controller or configure ports.
2275
2276		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2277
2278		I2C_PORT
2279
2280		(Only for MPC8260 CPU). The I/O port to use (the code
2281		assumes both bits are on the same port). Valid values
2282		are 0..3 for ports A..D.
2283
2284		I2C_ACTIVE
2285
2286		The code necessary to make the I2C data line active
2287		(driven).  If the data line is open collector, this
2288		define can be null.
2289
2290		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2291
2292		I2C_TRISTATE
2293
2294		The code necessary to make the I2C data line tri-stated
2295		(inactive).  If the data line is open collector, this
2296		define can be null.
2297
2298		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2299
2300		I2C_READ
2301
2302		Code that returns true if the I2C data line is high,
2303		false if it is low.
2304
2305		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2306
2307		I2C_SDA(bit)
2308
2309		If <bit> is true, sets the I2C data line high. If it
2310		is false, it clears it (low).
2311
2312		eg: #define I2C_SDA(bit) \
2313			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2314			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2315
2316		I2C_SCL(bit)
2317
2318		If <bit> is true, sets the I2C clock line high. If it
2319		is false, it clears it (low).
2320
2321		eg: #define I2C_SCL(bit) \
2322			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2323			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2324
2325		I2C_DELAY
2326
2327		This delay is invoked four times per clock cycle so this
2328		controls the rate of data transfer.  The data rate thus
2329		is 1 / (I2C_DELAY * 4). Often defined to be something
2330		like:
2331
2332		#define I2C_DELAY  udelay(2)
2333
2334		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2335
2336		If your arch supports the generic GPIO framework (asm/gpio.h),
2337		then you may alternatively define the two GPIOs that are to be
2338		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2339		have GPIO-based defaults assigned to them as appropriate.
2340
2341		You should define these to the GPIO value as given directly to
2342		the generic GPIO functions.
2343
2344		CONFIG_SYS_I2C_INIT_BOARD
2345
2346		When a board is reset during an i2c bus transfer
2347		chips might think that the current transfer is still
2348		in progress. On some boards it is possible to access
2349		the i2c SCLK line directly, either by using the
2350		processor pin as a GPIO or by having a second pin
2351		connected to the bus. If this option is defined a
2352		custom i2c_init_board() routine in boards/xxx/board.c
2353		is run early in the boot sequence.
2354
2355		CONFIG_SYS_I2C_BOARD_LATE_INIT
2356
2357		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2358		defined a custom i2c_board_late_init() routine in
2359		boards/xxx/board.c is run AFTER the operations in i2c_init()
2360		is completed. This callpoint can be used to unreset i2c bus
2361		using CPU i2c controller register accesses for CPUs whose i2c
2362		controller provide such a method. It is called at the end of
2363		i2c_init() to allow i2c_init operations to setup the i2c bus
2364		controller on the CPU (e.g. setting bus speed & slave address).
2365
2366		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2367
2368		This option enables configuration of bi_iic_fast[] flags
2369		in u-boot bd_info structure based on u-boot environment
2370		variable "i2cfast". (see also i2cfast)
2371
2372		CONFIG_I2C_MULTI_BUS
2373
2374		This option allows the use of multiple I2C buses, each of which
2375		must have a controller.	 At any point in time, only one bus is
2376		active.	 To switch to a different bus, use the 'i2c dev' command.
2377		Note that bus numbering is zero-based.
2378
2379		CONFIG_SYS_I2C_NOPROBES
2380
2381		This option specifies a list of I2C devices that will be skipped
2382		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2383		is set, specify a list of bus-device pairs.  Otherwise, specify
2384		a 1D array of device addresses
2385
2386		e.g.
2387			#undef	CONFIG_I2C_MULTI_BUS
2388			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2389
2390		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2391
2392			#define CONFIG_I2C_MULTI_BUS
2393			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2394
2395		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2396
2397		CONFIG_SYS_SPD_BUS_NUM
2398
2399		If defined, then this indicates the I2C bus number for DDR SPD.
2400		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2401
2402		CONFIG_SYS_RTC_BUS_NUM
2403
2404		If defined, then this indicates the I2C bus number for the RTC.
2405		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2406
2407		CONFIG_SYS_DTT_BUS_NUM
2408
2409		If defined, then this indicates the I2C bus number for the DTT.
2410		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2411
2412		CONFIG_SYS_I2C_DTT_ADDR:
2413
2414		If defined, specifies the I2C address of the DTT device.
2415		If not defined, then U-Boot uses predefined value for
2416		specified DTT device.
2417
2418		CONFIG_SOFT_I2C_READ_REPEATED_START
2419
2420		defining this will force the i2c_read() function in
2421		the soft_i2c driver to perform an I2C repeated start
2422		between writing the address pointer and reading the
2423		data.  If this define is omitted the default behaviour
2424		of doing a stop-start sequence will be used.  Most I2C
2425		devices can use either method, but some require one or
2426		the other.
2427
2428- SPI Support:	CONFIG_SPI
2429
2430		Enables SPI driver (so far only tested with
2431		SPI EEPROM, also an instance works with Crystal A/D and
2432		D/As on the SACSng board)
2433
2434		CONFIG_SH_SPI
2435
2436		Enables the driver for SPI controller on SuperH. Currently
2437		only SH7757 is supported.
2438
2439		CONFIG_SPI_X
2440
2441		Enables extended (16-bit) SPI EEPROM addressing.
2442		(symmetrical to CONFIG_I2C_X)
2443
2444		CONFIG_SOFT_SPI
2445
2446		Enables a software (bit-bang) SPI driver rather than
2447		using hardware support. This is a general purpose
2448		driver that only requires three general I/O port pins
2449		(two outputs, one input) to function. If this is
2450		defined, the board configuration must define several
2451		SPI configuration items (port pins to use, etc). For
2452		an example, see include/configs/sacsng.h.
2453
2454		CONFIG_HARD_SPI
2455
2456		Enables a hardware SPI driver for general-purpose reads
2457		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2458		must define a list of chip-select function pointers.
2459		Currently supported on some MPC8xxx processors.	 For an
2460		example, see include/configs/mpc8349emds.h.
2461
2462		CONFIG_MXC_SPI
2463
2464		Enables the driver for the SPI controllers on i.MX and MXC
2465		SoCs. Currently i.MX31/35/51 are supported.
2466
2467- FPGA Support: CONFIG_FPGA
2468
2469		Enables FPGA subsystem.
2470
2471		CONFIG_FPGA_<vendor>
2472
2473		Enables support for specific chip vendors.
2474		(ALTERA, XILINX)
2475
2476		CONFIG_FPGA_<family>
2477
2478		Enables support for FPGA family.
2479		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2480
2481		CONFIG_FPGA_COUNT
2482
2483		Specify the number of FPGA devices to support.
2484
2485		CONFIG_SYS_FPGA_PROG_FEEDBACK
2486
2487		Enable printing of hash marks during FPGA configuration.
2488
2489		CONFIG_SYS_FPGA_CHECK_BUSY
2490
2491		Enable checks on FPGA configuration interface busy
2492		status by the configuration function. This option
2493		will require a board or device specific function to
2494		be written.
2495
2496		CONFIG_FPGA_DELAY
2497
2498		If defined, a function that provides delays in the FPGA
2499		configuration driver.
2500
2501		CONFIG_SYS_FPGA_CHECK_CTRLC
2502		Allow Control-C to interrupt FPGA configuration
2503
2504		CONFIG_SYS_FPGA_CHECK_ERROR
2505
2506		Check for configuration errors during FPGA bitfile
2507		loading. For example, abort during Virtex II
2508		configuration if the INIT_B line goes low (which
2509		indicated a CRC error).
2510
2511		CONFIG_SYS_FPGA_WAIT_INIT
2512
2513		Maximum time to wait for the INIT_B line to deassert
2514		after PROB_B has been deasserted during a Virtex II
2515		FPGA configuration sequence. The default time is 500
2516		ms.
2517
2518		CONFIG_SYS_FPGA_WAIT_BUSY
2519
2520		Maximum time to wait for BUSY to deassert during
2521		Virtex II FPGA configuration. The default is 5 ms.
2522
2523		CONFIG_SYS_FPGA_WAIT_CONFIG
2524
2525		Time to wait after FPGA configuration. The default is
2526		200 ms.
2527
2528- Configuration Management:
2529		CONFIG_IDENT_STRING
2530
2531		If defined, this string will be added to the U-Boot
2532		version information (U_BOOT_VERSION)
2533
2534- Vendor Parameter Protection:
2535
2536		U-Boot considers the values of the environment
2537		variables "serial#" (Board Serial Number) and
2538		"ethaddr" (Ethernet Address) to be parameters that
2539		are set once by the board vendor / manufacturer, and
2540		protects these variables from casual modification by
2541		the user. Once set, these variables are read-only,
2542		and write or delete attempts are rejected. You can
2543		change this behaviour:
2544
2545		If CONFIG_ENV_OVERWRITE is #defined in your config
2546		file, the write protection for vendor parameters is
2547		completely disabled. Anybody can change or delete
2548		these parameters.
2549
2550		Alternatively, if you #define _both_ CONFIG_ETHADDR
2551		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2552		Ethernet address is installed in the environment,
2553		which can be changed exactly ONCE by the user. [The
2554		serial# is unaffected by this, i. e. it remains
2555		read-only.]
2556
2557		The same can be accomplished in a more flexible way
2558		for any variable by configuring the type of access
2559		to allow for those variables in the ".flags" variable
2560		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2561
2562- Protected RAM:
2563		CONFIG_PRAM
2564
2565		Define this variable to enable the reservation of
2566		"protected RAM", i. e. RAM which is not overwritten
2567		by U-Boot. Define CONFIG_PRAM to hold the number of
2568		kB you want to reserve for pRAM. You can overwrite
2569		this default value by defining an environment
2570		variable "pram" to the number of kB you want to
2571		reserve. Note that the board info structure will
2572		still show the full amount of RAM. If pRAM is
2573		reserved, a new environment variable "mem" will
2574		automatically be defined to hold the amount of
2575		remaining RAM in a form that can be passed as boot
2576		argument to Linux, for instance like that:
2577
2578			setenv bootargs ... mem=\${mem}
2579			saveenv
2580
2581		This way you can tell Linux not to use this memory,
2582		either, which results in a memory region that will
2583		not be affected by reboots.
2584
2585		*WARNING* If your board configuration uses automatic
2586		detection of the RAM size, you must make sure that
2587		this memory test is non-destructive. So far, the
2588		following board configurations are known to be
2589		"pRAM-clean":
2590
2591			IVMS8, IVML24, SPD8xx, TQM8xxL,
2592			HERMES, IP860, RPXlite, LWMON,
2593			FLAGADM, TQM8260
2594
2595- Access to physical memory region (> 4GB)
2596		Some basic support is provided for operations on memory not
2597		normally accessible to U-Boot - e.g. some architectures
2598		support access to more than 4GB of memory on 32-bit
2599		machines using physical address extension or similar.
2600		Define CONFIG_PHYSMEM to access this basic support, which
2601		currently only supports clearing the memory.
2602
2603- Error Recovery:
2604		CONFIG_PANIC_HANG
2605
2606		Define this variable to stop the system in case of a
2607		fatal error, so that you have to reset it manually.
2608		This is probably NOT a good idea for an embedded
2609		system where you want the system to reboot
2610		automatically as fast as possible, but it may be
2611		useful during development since you can try to debug
2612		the conditions that lead to the situation.
2613
2614		CONFIG_NET_RETRY_COUNT
2615
2616		This variable defines the number of retries for
2617		network operations like ARP, RARP, TFTP, or BOOTP
2618		before giving up the operation. If not defined, a
2619		default value of 5 is used.
2620
2621		CONFIG_ARP_TIMEOUT
2622
2623		Timeout waiting for an ARP reply in milliseconds.
2624
2625		CONFIG_NFS_TIMEOUT
2626
2627		Timeout in milliseconds used in NFS protocol.
2628		If you encounter "ERROR: Cannot umount" in nfs command,
2629		try longer timeout such as
2630		#define CONFIG_NFS_TIMEOUT 10000UL
2631
2632- Command Interpreter:
2633		CONFIG_AUTO_COMPLETE
2634
2635		Enable auto completion of commands using TAB.
2636
2637		Note that this feature has NOT been implemented yet
2638		for the "hush" shell.
2639
2640
2641		CONFIG_SYS_HUSH_PARSER
2642
2643		Define this variable to enable the "hush" shell (from
2644		Busybox) as command line interpreter, thus enabling
2645		powerful command line syntax like
2646		if...then...else...fi conditionals or `&&' and '||'
2647		constructs ("shell scripts").
2648
2649		If undefined, you get the old, much simpler behaviour
2650		with a somewhat smaller memory footprint.
2651
2652
2653		CONFIG_SYS_PROMPT_HUSH_PS2
2654
2655		This defines the secondary prompt string, which is
2656		printed when the command interpreter needs more input
2657		to complete a command. Usually "> ".
2658
2659	Note:
2660
2661		In the current implementation, the local variables
2662		space and global environment variables space are
2663		separated. Local variables are those you define by
2664		simply typing `name=value'. To access a local
2665		variable later on, you have write `$name' or
2666		`${name}'; to execute the contents of a variable
2667		directly type `$name' at the command prompt.
2668
2669		Global environment variables are those you use
2670		setenv/printenv to work with. To run a command stored
2671		in such a variable, you need to use the run command,
2672		and you must not use the '$' sign to access them.
2673
2674		To store commands and special characters in a
2675		variable, please use double quotation marks
2676		surrounding the whole text of the variable, instead
2677		of the backslashes before semicolons and special
2678		symbols.
2679
2680- Commandline Editing and History:
2681		CONFIG_CMDLINE_EDITING
2682
2683		Enable editing and History functions for interactive
2684		commandline input operations
2685
2686- Default Environment:
2687		CONFIG_EXTRA_ENV_SETTINGS
2688
2689		Define this to contain any number of null terminated
2690		strings (variable = value pairs) that will be part of
2691		the default environment compiled into the boot image.
2692
2693		For example, place something like this in your
2694		board's config file:
2695
2696		#define CONFIG_EXTRA_ENV_SETTINGS \
2697			"myvar1=value1\0" \
2698			"myvar2=value2\0"
2699
2700		Warning: This method is based on knowledge about the
2701		internal format how the environment is stored by the
2702		U-Boot code. This is NOT an official, exported
2703		interface! Although it is unlikely that this format
2704		will change soon, there is no guarantee either.
2705		You better know what you are doing here.
2706
2707		Note: overly (ab)use of the default environment is
2708		discouraged. Make sure to check other ways to preset
2709		the environment like the "source" command or the
2710		boot command first.
2711
2712		CONFIG_ENV_VARS_UBOOT_CONFIG
2713
2714		Define this in order to add variables describing the
2715		U-Boot build configuration to the default environment.
2716		These will be named arch, cpu, board, vendor, and soc.
2717
2718		Enabling this option will cause the following to be defined:
2719
2720		- CONFIG_SYS_ARCH
2721		- CONFIG_SYS_CPU
2722		- CONFIG_SYS_BOARD
2723		- CONFIG_SYS_VENDOR
2724		- CONFIG_SYS_SOC
2725
2726		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2727
2728		Define this in order to add variables describing certain
2729		run-time determined information about the hardware to the
2730		environment.  These will be named board_name, board_rev.
2731
2732		CONFIG_DELAY_ENVIRONMENT
2733
2734		Normally the environment is loaded when the board is
2735		intialised so that it is available to U-Boot. This inhibits
2736		that so that the environment is not available until
2737		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2738		this is instead controlled by the value of
2739		/config/load-environment.
2740
2741- DataFlash Support:
2742		CONFIG_HAS_DATAFLASH
2743
2744		Defining this option enables DataFlash features and
2745		allows to read/write in Dataflash via the standard
2746		commands cp, md...
2747
2748- Serial Flash support
2749		CONFIG_CMD_SF
2750
2751		Defining this option enables SPI flash commands
2752		'sf probe/read/write/erase/update'.
2753
2754		Usage requires an initial 'probe' to define the serial
2755		flash parameters, followed by read/write/erase/update
2756		commands.
2757
2758		The following defaults may be provided by the platform
2759		to handle the common case when only a single serial
2760		flash is present on the system.
2761
2762		CONFIG_SF_DEFAULT_BUS		Bus identifier
2763		CONFIG_SF_DEFAULT_CS		Chip-select
2764		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2765		CONFIG_SF_DEFAULT_SPEED		in Hz
2766
2767		CONFIG_CMD_SF_TEST
2768
2769		Define this option to include a destructive SPI flash
2770		test ('sf test').
2771
2772		CONFIG_SPI_FLASH_BAR		Ban/Extended Addr Reg
2773
2774		Define this option to use the Bank addr/Extended addr
2775		support on SPI flashes which has size > 16Mbytes.
2776
2777		CONFIG_SF_DUAL_FLASH		Dual flash memories
2778
2779		Define this option to use dual flash support where two flash
2780		memories can be connected with a given cs line.
2781		currently Xilinx Zynq qspi support these type of connections.
2782
2783- SystemACE Support:
2784		CONFIG_SYSTEMACE
2785
2786		Adding this option adds support for Xilinx SystemACE
2787		chips attached via some sort of local bus. The address
2788		of the chip must also be defined in the
2789		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2790
2791		#define CONFIG_SYSTEMACE
2792		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2793
2794		When SystemACE support is added, the "ace" device type
2795		becomes available to the fat commands, i.e. fatls.
2796
2797- TFTP Fixed UDP Port:
2798		CONFIG_TFTP_PORT
2799
2800		If this is defined, the environment variable tftpsrcp
2801		is used to supply the TFTP UDP source port value.
2802		If tftpsrcp isn't defined, the normal pseudo-random port
2803		number generator is used.
2804
2805		Also, the environment variable tftpdstp is used to supply
2806		the TFTP UDP destination port value.  If tftpdstp isn't
2807		defined, the normal port 69 is used.
2808
2809		The purpose for tftpsrcp is to allow a TFTP server to
2810		blindly start the TFTP transfer using the pre-configured
2811		target IP address and UDP port. This has the effect of
2812		"punching through" the (Windows XP) firewall, allowing
2813		the remainder of the TFTP transfer to proceed normally.
2814		A better solution is to properly configure the firewall,
2815		but sometimes that is not allowed.
2816
2817- Hashing support:
2818		CONFIG_CMD_HASH
2819
2820		This enables a generic 'hash' command which can produce
2821		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
2822
2823		CONFIG_HASH_VERIFY
2824
2825		Enable the hash verify command (hash -v). This adds to code
2826		size a little.
2827
2828		CONFIG_SHA1 - support SHA1 hashing
2829		CONFIG_SHA256 - support SHA256 hashing
2830
2831		Note: There is also a sha1sum command, which should perhaps
2832		be deprecated in favour of 'hash sha1'.
2833
2834- Freescale i.MX specific commands:
2835		CONFIG_CMD_HDMIDETECT
2836		This enables 'hdmidet' command which returns true if an
2837		HDMI monitor is detected.  This command is i.MX 6 specific.
2838
2839		CONFIG_CMD_BMODE
2840		This enables the 'bmode' (bootmode) command for forcing
2841		a boot from specific media.
2842
2843		This is useful for forcing the ROM's usb downloader to
2844		activate upon a watchdog reset which is nice when iterating
2845		on U-Boot.  Using the reset button or running bmode normal
2846		will set it back to normal.  This command currently
2847		supports i.MX53 and i.MX6.
2848
2849- Signing support:
2850		CONFIG_RSA
2851
2852		This enables the RSA algorithm used for FIT image verification
2853		in U-Boot. See doc/uImage.FIT/signature.txt for more information.
2854
2855		The signing part is build into mkimage regardless of this
2856		option.
2857
2858
2859- Show boot progress:
2860		CONFIG_SHOW_BOOT_PROGRESS
2861
2862		Defining this option allows to add some board-
2863		specific code (calling a user-provided function
2864		"show_boot_progress(int)") that enables you to show
2865		the system's boot progress on some display (for
2866		example, some LED's) on your board. At the moment,
2867		the following checkpoints are implemented:
2868
2869- Detailed boot stage timing
2870		CONFIG_BOOTSTAGE
2871		Define this option to get detailed timing of each stage
2872		of the boot process.
2873
2874		CONFIG_BOOTSTAGE_USER_COUNT
2875		This is the number of available user bootstage records.
2876		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
2877		a new ID will be allocated from this stash. If you exceed
2878		the limit, recording will stop.
2879
2880		CONFIG_BOOTSTAGE_REPORT
2881		Define this to print a report before boot, similar to this:
2882
2883		Timer summary in microseconds:
2884		       Mark    Elapsed  Stage
2885			  0          0  reset
2886		  3,575,678  3,575,678  board_init_f start
2887		  3,575,695         17  arch_cpu_init A9
2888		  3,575,777         82  arch_cpu_init done
2889		  3,659,598     83,821  board_init_r start
2890		  3,910,375    250,777  main_loop
2891		 29,916,167 26,005,792  bootm_start
2892		 30,361,327    445,160  start_kernel
2893
2894		CONFIG_CMD_BOOTSTAGE
2895		Add a 'bootstage' command which supports printing a report
2896		and un/stashing of bootstage data.
2897
2898		CONFIG_BOOTSTAGE_FDT
2899		Stash the bootstage information in the FDT. A root 'bootstage'
2900		node is created with each bootstage id as a child. Each child
2901		has a 'name' property and either 'mark' containing the
2902		mark time in microsecond, or 'accum' containing the
2903		accumulated time for that bootstage id in microseconds.
2904		For example:
2905
2906		bootstage {
2907			154 {
2908				name = "board_init_f";
2909				mark = <3575678>;
2910			};
2911			170 {
2912				name = "lcd";
2913				accum = <33482>;
2914			};
2915		};
2916
2917		Code in the Linux kernel can find this in /proc/devicetree.
2918
2919Legacy uImage format:
2920
2921  Arg	Where			When
2922    1	common/cmd_bootm.c	before attempting to boot an image
2923   -1	common/cmd_bootm.c	Image header has bad	 magic number
2924    2	common/cmd_bootm.c	Image header has correct magic number
2925   -2	common/cmd_bootm.c	Image header has bad	 checksum
2926    3	common/cmd_bootm.c	Image header has correct checksum
2927   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2928    4	common/cmd_bootm.c	Image data   has correct checksum
2929   -4	common/cmd_bootm.c	Image is for unsupported architecture
2930    5	common/cmd_bootm.c	Architecture check OK
2931   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2932    6	common/cmd_bootm.c	Image Type check OK
2933   -6	common/cmd_bootm.c	gunzip uncompression error
2934   -7	common/cmd_bootm.c	Unimplemented compression type
2935    7	common/cmd_bootm.c	Uncompression OK
2936    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2937   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2938
2939    9	common/image.c		Start initial ramdisk verification
2940  -10	common/image.c		Ramdisk header has bad	   magic number
2941  -11	common/image.c		Ramdisk header has bad	   checksum
2942   10	common/image.c		Ramdisk header is OK
2943  -12	common/image.c		Ramdisk data   has bad	   checksum
2944   11	common/image.c		Ramdisk data   has correct checksum
2945   12	common/image.c		Ramdisk verification complete, start loading
2946  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2947   13	common/image.c		Start multifile image verification
2948   14	common/image.c		No initial ramdisk, no multifile, continue.
2949
2950   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2951
2952  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2953  -31	post/post.c		POST test failed, detected by post_output_backlog()
2954  -32	post/post.c		POST test failed, detected by post_run_single()
2955
2956   34	common/cmd_doc.c	before loading a Image from a DOC device
2957  -35	common/cmd_doc.c	Bad usage of "doc" command
2958   35	common/cmd_doc.c	correct usage of "doc" command
2959  -36	common/cmd_doc.c	No boot device
2960   36	common/cmd_doc.c	correct boot device
2961  -37	common/cmd_doc.c	Unknown Chip ID on boot device
2962   37	common/cmd_doc.c	correct chip ID found, device available
2963  -38	common/cmd_doc.c	Read Error on boot device
2964   38	common/cmd_doc.c	reading Image header from DOC device OK
2965  -39	common/cmd_doc.c	Image header has bad magic number
2966   39	common/cmd_doc.c	Image header has correct magic number
2967  -40	common/cmd_doc.c	Error reading Image from DOC device
2968   40	common/cmd_doc.c	Image header has correct magic number
2969   41	common/cmd_ide.c	before loading a Image from a IDE device
2970  -42	common/cmd_ide.c	Bad usage of "ide" command
2971   42	common/cmd_ide.c	correct usage of "ide" command
2972  -43	common/cmd_ide.c	No boot device
2973   43	common/cmd_ide.c	boot device found
2974  -44	common/cmd_ide.c	Device not available
2975   44	common/cmd_ide.c	Device available
2976  -45	common/cmd_ide.c	wrong partition selected
2977   45	common/cmd_ide.c	partition selected
2978  -46	common/cmd_ide.c	Unknown partition table
2979   46	common/cmd_ide.c	valid partition table found
2980  -47	common/cmd_ide.c	Invalid partition type
2981   47	common/cmd_ide.c	correct partition type
2982  -48	common/cmd_ide.c	Error reading Image Header on boot device
2983   48	common/cmd_ide.c	reading Image Header from IDE device OK
2984  -49	common/cmd_ide.c	Image header has bad magic number
2985   49	common/cmd_ide.c	Image header has correct magic number
2986  -50	common/cmd_ide.c	Image header has bad	 checksum
2987   50	common/cmd_ide.c	Image header has correct checksum
2988  -51	common/cmd_ide.c	Error reading Image from IDE device
2989   51	common/cmd_ide.c	reading Image from IDE device OK
2990   52	common/cmd_nand.c	before loading a Image from a NAND device
2991  -53	common/cmd_nand.c	Bad usage of "nand" command
2992   53	common/cmd_nand.c	correct usage of "nand" command
2993  -54	common/cmd_nand.c	No boot device
2994   54	common/cmd_nand.c	boot device found
2995  -55	common/cmd_nand.c	Unknown Chip ID on boot device
2996   55	common/cmd_nand.c	correct chip ID found, device available
2997  -56	common/cmd_nand.c	Error reading Image Header on boot device
2998   56	common/cmd_nand.c	reading Image Header from NAND device OK
2999  -57	common/cmd_nand.c	Image header has bad magic number
3000   57	common/cmd_nand.c	Image header has correct magic number
3001  -58	common/cmd_nand.c	Error reading Image from NAND device
3002   58	common/cmd_nand.c	reading Image from NAND device OK
3003
3004  -60	common/env_common.c	Environment has a bad CRC, using default
3005
3006   64	net/eth.c		starting with Ethernet configuration.
3007  -64	net/eth.c		no Ethernet found.
3008   65	net/eth.c		Ethernet found.
3009
3010  -80	common/cmd_net.c	usage wrong
3011   80	common/cmd_net.c	before calling NetLoop()
3012  -81	common/cmd_net.c	some error in NetLoop() occurred
3013   81	common/cmd_net.c	NetLoop() back without error
3014  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
3015   82	common/cmd_net.c	trying automatic boot
3016   83	common/cmd_net.c	running "source" command
3017  -83	common/cmd_net.c	some error in automatic boot or "source" command
3018   84	common/cmd_net.c	end without errors
3019
3020FIT uImage format:
3021
3022  Arg	Where			When
3023  100	common/cmd_bootm.c	Kernel FIT Image has correct format
3024 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
3025  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
3026 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
3027  102	common/cmd_bootm.c	Kernel unit name specified
3028 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
3029  103	common/cmd_bootm.c	Found configuration node
3030  104	common/cmd_bootm.c	Got kernel subimage node offset
3031 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
3032  105	common/cmd_bootm.c	Kernel subimage hash verification OK
3033 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
3034  106	common/cmd_bootm.c	Architecture check OK
3035 -106	common/cmd_bootm.c	Kernel subimage has wrong type
3036  107	common/cmd_bootm.c	Kernel subimage type OK
3037 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
3038  108	common/cmd_bootm.c	Got kernel subimage data/size
3039 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
3040 -109	common/cmd_bootm.c	Can't get kernel subimage type
3041 -110	common/cmd_bootm.c	Can't get kernel subimage comp
3042 -111	common/cmd_bootm.c	Can't get kernel subimage os
3043 -112	common/cmd_bootm.c	Can't get kernel subimage load address
3044 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
3045
3046  120	common/image.c		Start initial ramdisk verification
3047 -120	common/image.c		Ramdisk FIT image has incorrect format
3048  121	common/image.c		Ramdisk FIT image has correct format
3049  122	common/image.c		No ramdisk subimage unit name, using configuration
3050 -122	common/image.c		Can't get configuration for ramdisk subimage
3051  123	common/image.c		Ramdisk unit name specified
3052 -124	common/image.c		Can't get ramdisk subimage node offset
3053  125	common/image.c		Got ramdisk subimage node offset
3054 -125	common/image.c		Ramdisk subimage hash verification failed
3055  126	common/image.c		Ramdisk subimage hash verification OK
3056 -126	common/image.c		Ramdisk subimage for unsupported architecture
3057  127	common/image.c		Architecture check OK
3058 -127	common/image.c		Can't get ramdisk subimage data/size
3059  128	common/image.c		Got ramdisk subimage data/size
3060  129	common/image.c		Can't get ramdisk load address
3061 -129	common/image.c		Got ramdisk load address
3062
3063 -130	common/cmd_doc.c	Incorrect FIT image format
3064  131	common/cmd_doc.c	FIT image format OK
3065
3066 -140	common/cmd_ide.c	Incorrect FIT image format
3067  141	common/cmd_ide.c	FIT image format OK
3068
3069 -150	common/cmd_nand.c	Incorrect FIT image format
3070  151	common/cmd_nand.c	FIT image format OK
3071
3072- FIT image support:
3073		CONFIG_FIT
3074		Enable support for the FIT uImage format.
3075
3076		CONFIG_FIT_BEST_MATCH
3077		When no configuration is explicitly selected, default to the
3078		one whose fdt's compatibility field best matches that of
3079		U-Boot itself. A match is considered "best" if it matches the
3080		most specific compatibility entry of U-Boot's fdt's root node.
3081		The order of entries in the configuration's fdt is ignored.
3082
3083		CONFIG_FIT_SIGNATURE
3084		This option enables signature verification of FIT uImages,
3085		using a hash signed and verified using RSA. See
3086		doc/uImage.FIT/signature.txt for more details.
3087
3088- Standalone program support:
3089		CONFIG_STANDALONE_LOAD_ADDR
3090
3091		This option defines a board specific value for the
3092		address where standalone program gets loaded, thus
3093		overwriting the architecture dependent default
3094		settings.
3095
3096- Frame Buffer Address:
3097		CONFIG_FB_ADDR
3098
3099		Define CONFIG_FB_ADDR if you want to use specific
3100		address for frame buffer.  This is typically the case
3101		when using a graphics controller has separate video
3102		memory.  U-Boot will then place the frame buffer at
3103		the given address instead of dynamically reserving it
3104		in system RAM by calling lcd_setmem(), which grabs
3105		the memory for the frame buffer depending on the
3106		configured panel size.
3107
3108		Please see board_init_f function.
3109
3110- Automatic software updates via TFTP server
3111		CONFIG_UPDATE_TFTP
3112		CONFIG_UPDATE_TFTP_CNT_MAX
3113		CONFIG_UPDATE_TFTP_MSEC_MAX
3114
3115		These options enable and control the auto-update feature;
3116		for a more detailed description refer to doc/README.update.
3117
3118- MTD Support (mtdparts command, UBI support)
3119		CONFIG_MTD_DEVICE
3120
3121		Adds the MTD device infrastructure from the Linux kernel.
3122		Needed for mtdparts command support.
3123
3124		CONFIG_MTD_PARTITIONS
3125
3126		Adds the MTD partitioning infrastructure from the Linux
3127		kernel. Needed for UBI support.
3128
3129- UBI support
3130		CONFIG_CMD_UBI
3131
3132		Adds commands for interacting with MTD partitions formatted
3133		with the UBI flash translation layer
3134
3135		Requires also defining CONFIG_RBTREE
3136
3137		CONFIG_UBI_SILENCE_MSG
3138
3139		Make the verbose messages from UBI stop printing.  This leaves
3140		warnings and errors enabled.
3141
3142- UBIFS support
3143		CONFIG_CMD_UBIFS
3144
3145		Adds commands for interacting with UBI volumes formatted as
3146		UBIFS.  UBIFS is read-only in u-boot.
3147
3148		Requires UBI support as well as CONFIG_LZO
3149
3150		CONFIG_UBIFS_SILENCE_MSG
3151
3152		Make the verbose messages from UBIFS stop printing.  This leaves
3153		warnings and errors enabled.
3154
3155- SPL framework
3156		CONFIG_SPL
3157		Enable building of SPL globally.
3158
3159		CONFIG_SPL_LDSCRIPT
3160		LDSCRIPT for linking the SPL binary.
3161
3162		CONFIG_SPL_MAX_FOOTPRINT
3163		Maximum size in memory allocated to the SPL, BSS included.
3164		When defined, the linker checks that the actual memory
3165		used by SPL from _start to __bss_end does not exceed it.
3166		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3167		must not be both defined at the same time.
3168
3169		CONFIG_SPL_MAX_SIZE
3170		Maximum size of the SPL image (text, data, rodata, and
3171		linker lists sections), BSS excluded.
3172		When defined, the linker checks that the actual size does
3173		not exceed it.
3174
3175		CONFIG_SPL_TEXT_BASE
3176		TEXT_BASE for linking the SPL binary.
3177
3178		CONFIG_SPL_RELOC_TEXT_BASE
3179		Address to relocate to.  If unspecified, this is equal to
3180		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3181
3182		CONFIG_SPL_BSS_START_ADDR
3183		Link address for the BSS within the SPL binary.
3184
3185		CONFIG_SPL_BSS_MAX_SIZE
3186		Maximum size in memory allocated to the SPL BSS.
3187		When defined, the linker checks that the actual memory used
3188		by SPL from __bss_start to __bss_end does not exceed it.
3189		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3190		must not be both defined at the same time.
3191
3192		CONFIG_SPL_STACK
3193		Adress of the start of the stack SPL will use
3194
3195		CONFIG_SPL_RELOC_STACK
3196		Adress of the start of the stack SPL will use after
3197		relocation.  If unspecified, this is equal to
3198		CONFIG_SPL_STACK.
3199
3200		CONFIG_SYS_SPL_MALLOC_START
3201		Starting address of the malloc pool used in SPL.
3202
3203		CONFIG_SYS_SPL_MALLOC_SIZE
3204		The size of the malloc pool used in SPL.
3205
3206		CONFIG_SPL_FRAMEWORK
3207		Enable the SPL framework under common/.  This framework
3208		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3209		NAND loading of the Linux Kernel.
3210
3211		CONFIG_SPL_DISPLAY_PRINT
3212		For ARM, enable an optional function to print more information
3213		about the running system.
3214
3215		CONFIG_SPL_INIT_MINIMAL
3216		Arch init code should be built for a very small image
3217
3218		CONFIG_SPL_LIBCOMMON_SUPPORT
3219		Support for common/libcommon.o in SPL binary
3220
3221		CONFIG_SPL_LIBDISK_SUPPORT
3222		Support for disk/libdisk.o in SPL binary
3223
3224		CONFIG_SPL_I2C_SUPPORT
3225		Support for drivers/i2c/libi2c.o in SPL binary
3226
3227		CONFIG_SPL_GPIO_SUPPORT
3228		Support for drivers/gpio/libgpio.o in SPL binary
3229
3230		CONFIG_SPL_MMC_SUPPORT
3231		Support for drivers/mmc/libmmc.o in SPL binary
3232
3233		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3234		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3235		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
3236		Address, size and partition on the MMC to load U-Boot from
3237		when the MMC is being used in raw mode.
3238
3239		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3240		Sector to load kernel uImage from when MMC is being
3241		used in raw mode (for Falcon mode)
3242
3243		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3244		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3245		Sector and number of sectors to load kernel argument
3246		parameters from when MMC is being used in raw mode
3247		(for falcon mode)
3248
3249		CONFIG_SPL_FAT_SUPPORT
3250		Support for fs/fat/libfat.o in SPL binary
3251
3252		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
3253		Filename to read to load U-Boot when reading from FAT
3254
3255		CONFIG_SPL_FAT_LOAD_KERNEL_NAME
3256		Filename to read to load kernel uImage when reading
3257		from FAT (for Falcon mode)
3258
3259		CONFIG_SPL_FAT_LOAD_ARGS_NAME
3260		Filename to read to load kernel argument parameters
3261		when reading from FAT (for Falcon mode)
3262
3263		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3264		Set this for NAND SPL on PPC mpc83xx targets, so that
3265		start.S waits for the rest of the SPL to load before
3266		continuing (the hardware starts execution after just
3267		loading the first page rather than the full 4K).
3268
3269		CONFIG_SPL_NAND_BASE
3270		Include nand_base.c in the SPL.  Requires
3271		CONFIG_SPL_NAND_DRIVERS.
3272
3273		CONFIG_SPL_NAND_DRIVERS
3274		SPL uses normal NAND drivers, not minimal drivers.
3275
3276		CONFIG_SPL_NAND_ECC
3277		Include standard software ECC in the SPL
3278
3279		CONFIG_SPL_NAND_SIMPLE
3280		Support for NAND boot using simple NAND drivers that
3281		expose the cmd_ctrl() interface.
3282
3283		CONFIG_SPL_MPC8XXX_INIT_DDR_SUPPORT
3284		Set for the SPL on PPC mpc8xxx targets, support for
3285		drivers/ddr/fsl/libddr.o in SPL binary.
3286
3287		CONFIG_SPL_COMMON_INIT_DDR
3288		Set for common ddr init with serial presence detect in
3289		SPL binary.
3290
3291		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3292		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3293		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3294		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3295		CONFIG_SYS_NAND_ECCBYTES
3296		Defines the size and behavior of the NAND that SPL uses
3297		to read U-Boot
3298
3299		CONFIG_SPL_NAND_BOOT
3300		Add support NAND boot
3301
3302		CONFIG_SYS_NAND_U_BOOT_OFFS
3303		Location in NAND to read U-Boot from
3304
3305		CONFIG_SYS_NAND_U_BOOT_DST
3306		Location in memory to load U-Boot to
3307
3308		CONFIG_SYS_NAND_U_BOOT_SIZE
3309		Size of image to load
3310
3311		CONFIG_SYS_NAND_U_BOOT_START
3312		Entry point in loaded image to jump to
3313
3314		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3315		Define this if you need to first read the OOB and then the
3316		data. This is used for example on davinci plattforms.
3317
3318		CONFIG_SPL_OMAP3_ID_NAND
3319		Support for an OMAP3-specific set of functions to return the
3320		ID and MFR of the first attached NAND chip, if present.
3321
3322		CONFIG_SPL_SERIAL_SUPPORT
3323		Support for drivers/serial/libserial.o in SPL binary
3324
3325		CONFIG_SPL_SPI_FLASH_SUPPORT
3326		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
3327
3328		CONFIG_SPL_SPI_SUPPORT
3329		Support for drivers/spi/libspi.o in SPL binary
3330
3331		CONFIG_SPL_RAM_DEVICE
3332		Support for running image already present in ram, in SPL binary
3333
3334		CONFIG_SPL_LIBGENERIC_SUPPORT
3335		Support for lib/libgeneric.o in SPL binary
3336
3337		CONFIG_SPL_ENV_SUPPORT
3338		Support for the environment operating in SPL binary
3339
3340		CONFIG_SPL_NET_SUPPORT
3341		Support for the net/libnet.o in SPL binary.
3342		It conflicts with SPL env from storage medium specified by
3343		CONFIG_ENV_IS_xxx but CONFIG_ENV_IS_NOWHERE
3344
3345		CONFIG_SPL_PAD_TO
3346		Image offset to which the SPL should be padded before appending
3347		the SPL payload. By default, this is defined as
3348		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3349		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3350		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3351
3352		CONFIG_SPL_TARGET
3353		Final target image containing SPL and payload.  Some SPLs
3354		use an arch-specific makefile fragment instead, for
3355		example if more than one image needs to be produced.
3356
3357		CONFIG_FIT_SPL_PRINT
3358		Printing information about a FIT image adds quite a bit of
3359		code to SPL. So this is normally disabled in SPL. Use this
3360		option to re-enable it. This will affect the output of the
3361		bootm command when booting a FIT image.
3362
3363- TPL framework
3364		CONFIG_TPL
3365		Enable building of TPL globally.
3366
3367		CONFIG_TPL_PAD_TO
3368		Image offset to which the TPL should be padded before appending
3369		the TPL payload. By default, this is defined as
3370		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3371		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3372		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3373
3374Modem Support:
3375--------------
3376
3377[so far only for SMDK2400 boards]
3378
3379- Modem support enable:
3380		CONFIG_MODEM_SUPPORT
3381
3382- RTS/CTS Flow control enable:
3383		CONFIG_HWFLOW
3384
3385- Modem debug support:
3386		CONFIG_MODEM_SUPPORT_DEBUG
3387
3388		Enables debugging stuff (char screen[1024], dbg())
3389		for modem support. Useful only with BDI2000.
3390
3391- Interrupt support (PPC):
3392
3393		There are common interrupt_init() and timer_interrupt()
3394		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3395		for CPU specific initialization. interrupt_init_cpu()
3396		should set decrementer_count to appropriate value. If
3397		CPU resets decrementer automatically after interrupt
3398		(ppc4xx) it should set decrementer_count to zero.
3399		timer_interrupt() calls timer_interrupt_cpu() for CPU
3400		specific handling. If board has watchdog / status_led
3401		/ other_activity_monitor it works automatically from
3402		general timer_interrupt().
3403
3404- General:
3405
3406		In the target system modem support is enabled when a
3407		specific key (key combination) is pressed during
3408		power-on. Otherwise U-Boot will boot normally
3409		(autoboot). The key_pressed() function is called from
3410		board_init(). Currently key_pressed() is a dummy
3411		function, returning 1 and thus enabling modem
3412		initialization.
3413
3414		If there are no modem init strings in the
3415		environment, U-Boot proceed to autoboot; the
3416		previous output (banner, info printfs) will be
3417		suppressed, though.
3418
3419		See also: doc/README.Modem
3420
3421Board initialization settings:
3422------------------------------
3423
3424During Initialization u-boot calls a number of board specific functions
3425to allow the preparation of board specific prerequisites, e.g. pin setup
3426before drivers are initialized. To enable these callbacks the
3427following configuration macros have to be defined. Currently this is
3428architecture specific, so please check arch/your_architecture/lib/board.c
3429typically in board_init_f() and board_init_r().
3430
3431- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3432- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3433- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3434- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3435
3436Configuration Settings:
3437-----------------------
3438
3439- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3440		undefine this when you're short of memory.
3441
3442- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3443		width of the commands listed in the 'help' command output.
3444
3445- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3446		prompt for user input.
3447
3448- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3449
3450- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3451
3452- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3453
3454- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3455		the application (usually a Linux kernel) when it is
3456		booted
3457
3458- CONFIG_SYS_BAUDRATE_TABLE:
3459		List of legal baudrate settings for this board.
3460
3461- CONFIG_SYS_CONSOLE_INFO_QUIET
3462		Suppress display of console information at boot.
3463
3464- CONFIG_SYS_CONSOLE_IS_IN_ENV
3465		If the board specific function
3466			extern int overwrite_console (void);
3467		returns 1, the stdin, stderr and stdout are switched to the
3468		serial port, else the settings in the environment are used.
3469
3470- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3471		Enable the call to overwrite_console().
3472
3473- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3474		Enable overwrite of previous console environment settings.
3475
3476- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3477		Begin and End addresses of the area used by the
3478		simple memory test.
3479
3480- CONFIG_SYS_ALT_MEMTEST:
3481		Enable an alternate, more extensive memory test.
3482
3483- CONFIG_SYS_MEMTEST_SCRATCH:
3484		Scratch address used by the alternate memory test
3485		You only need to set this if address zero isn't writeable
3486
3487- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
3488		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3489		this specified memory area will get subtracted from the top
3490		(end) of RAM and won't get "touched" at all by U-Boot. By
3491		fixing up gd->ram_size the Linux kernel should gets passed
3492		the now "corrected" memory size and won't touch it either.
3493		This should work for arch/ppc and arch/powerpc. Only Linux
3494		board ports in arch/powerpc with bootwrapper support that
3495		recalculate the memory size from the SDRAM controller setup
3496		will have to get fixed in Linux additionally.
3497
3498		This option can be used as a workaround for the 440EPx/GRx
3499		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3500		be touched.
3501
3502		WARNING: Please make sure that this value is a multiple of
3503		the Linux page size (normally 4k). If this is not the case,
3504		then the end address of the Linux memory will be located at a
3505		non page size aligned address and this could cause major
3506		problems.
3507
3508- CONFIG_SYS_LOADS_BAUD_CHANGE:
3509		Enable temporary baudrate change while serial download
3510
3511- CONFIG_SYS_SDRAM_BASE:
3512		Physical start address of SDRAM. _Must_ be 0 here.
3513
3514- CONFIG_SYS_MBIO_BASE:
3515		Physical start address of Motherboard I/O (if using a
3516		Cogent motherboard)
3517
3518- CONFIG_SYS_FLASH_BASE:
3519		Physical start address of Flash memory.
3520
3521- CONFIG_SYS_MONITOR_BASE:
3522		Physical start address of boot monitor code (set by
3523		make config files to be same as the text base address
3524		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3525		CONFIG_SYS_FLASH_BASE when booting from flash.
3526
3527- CONFIG_SYS_MONITOR_LEN:
3528		Size of memory reserved for monitor code, used to
3529		determine _at_compile_time_ (!) if the environment is
3530		embedded within the U-Boot image, or in a separate
3531		flash sector.
3532
3533- CONFIG_SYS_MALLOC_LEN:
3534		Size of DRAM reserved for malloc() use.
3535
3536- CONFIG_SYS_BOOTM_LEN:
3537		Normally compressed uImages are limited to an
3538		uncompressed size of 8 MBytes. If this is not enough,
3539		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3540		to adjust this setting to your needs.
3541
3542- CONFIG_SYS_BOOTMAPSZ:
3543		Maximum size of memory mapped by the startup code of
3544		the Linux kernel; all data that must be processed by
3545		the Linux kernel (bd_info, boot arguments, FDT blob if
3546		used) must be put below this limit, unless "bootm_low"
3547		environment variable is defined and non-zero. In such case
3548		all data for the Linux kernel must be between "bootm_low"
3549		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3550		variable "bootm_mapsize" will override the value of
3551		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3552		then the value in "bootm_size" will be used instead.
3553
3554- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3555		Enable initrd_high functionality.  If defined then the
3556		initrd_high feature is enabled and the bootm ramdisk subcommand
3557		is enabled.
3558
3559- CONFIG_SYS_BOOT_GET_CMDLINE:
3560		Enables allocating and saving kernel cmdline in space between
3561		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3562
3563- CONFIG_SYS_BOOT_GET_KBD:
3564		Enables allocating and saving a kernel copy of the bd_info in
3565		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3566
3567- CONFIG_SYS_MAX_FLASH_BANKS:
3568		Max number of Flash memory banks
3569
3570- CONFIG_SYS_MAX_FLASH_SECT:
3571		Max number of sectors on a Flash chip
3572
3573- CONFIG_SYS_FLASH_ERASE_TOUT:
3574		Timeout for Flash erase operations (in ms)
3575
3576- CONFIG_SYS_FLASH_WRITE_TOUT:
3577		Timeout for Flash write operations (in ms)
3578
3579- CONFIG_SYS_FLASH_LOCK_TOUT
3580		Timeout for Flash set sector lock bit operation (in ms)
3581
3582- CONFIG_SYS_FLASH_UNLOCK_TOUT
3583		Timeout for Flash clear lock bits operation (in ms)
3584
3585- CONFIG_SYS_FLASH_PROTECTION
3586		If defined, hardware flash sectors protection is used
3587		instead of U-Boot software protection.
3588
3589- CONFIG_SYS_DIRECT_FLASH_TFTP:
3590
3591		Enable TFTP transfers directly to flash memory;
3592		without this option such a download has to be
3593		performed in two steps: (1) download to RAM, and (2)
3594		copy from RAM to flash.
3595
3596		The two-step approach is usually more reliable, since
3597		you can check if the download worked before you erase
3598		the flash, but in some situations (when system RAM is
3599		too limited to allow for a temporary copy of the
3600		downloaded image) this option may be very useful.
3601
3602- CONFIG_SYS_FLASH_CFI:
3603		Define if the flash driver uses extra elements in the
3604		common flash structure for storing flash geometry.
3605
3606- CONFIG_FLASH_CFI_DRIVER
3607		This option also enables the building of the cfi_flash driver
3608		in the drivers directory
3609
3610- CONFIG_FLASH_CFI_MTD
3611		This option enables the building of the cfi_mtd driver
3612		in the drivers directory. The driver exports CFI flash
3613		to the MTD layer.
3614
3615- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3616		Use buffered writes to flash.
3617
3618- CONFIG_FLASH_SPANSION_S29WS_N
3619		s29ws-n MirrorBit flash has non-standard addresses for buffered
3620		write commands.
3621
3622- CONFIG_SYS_FLASH_QUIET_TEST
3623		If this option is defined, the common CFI flash doesn't
3624		print it's warning upon not recognized FLASH banks. This
3625		is useful, if some of the configured banks are only
3626		optionally available.
3627
3628- CONFIG_FLASH_SHOW_PROGRESS
3629		If defined (must be an integer), print out countdown
3630		digits and dots.  Recommended value: 45 (9..1) for 80
3631		column displays, 15 (3..1) for 40 column displays.
3632
3633- CONFIG_FLASH_VERIFY
3634		If defined, the content of the flash (destination) is compared
3635		against the source after the write operation. An error message
3636		will be printed when the contents are not identical.
3637		Please note that this option is useless in nearly all cases,
3638		since such flash programming errors usually are detected earlier
3639		while unprotecting/erasing/programming. Please only enable
3640		this option if you really know what you are doing.
3641
3642- CONFIG_SYS_RX_ETH_BUFFER:
3643		Defines the number of Ethernet receive buffers. On some
3644		Ethernet controllers it is recommended to set this value
3645		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3646		buffers can be full shortly after enabling the interface
3647		on high Ethernet traffic.
3648		Defaults to 4 if not defined.
3649
3650- CONFIG_ENV_MAX_ENTRIES
3651
3652	Maximum number of entries in the hash table that is used
3653	internally to store the environment settings. The default
3654	setting is supposed to be generous and should work in most
3655	cases. This setting can be used to tune behaviour; see
3656	lib/hashtable.c for details.
3657
3658- CONFIG_ENV_FLAGS_LIST_DEFAULT
3659- CONFIG_ENV_FLAGS_LIST_STATIC
3660	Enable validation of the values given to environment variables when
3661	calling env set.  Variables can be restricted to only decimal,
3662	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3663	the variables can also be restricted to IP address or MAC address.
3664
3665	The format of the list is:
3666		type_attribute = [s|d|x|b|i|m]
3667		access_atribute = [a|r|o|c]
3668		attributes = type_attribute[access_atribute]
3669		entry = variable_name[:attributes]
3670		list = entry[,list]
3671
3672	The type attributes are:
3673		s - String (default)
3674		d - Decimal
3675		x - Hexadecimal
3676		b - Boolean ([1yYtT|0nNfF])
3677		i - IP address
3678		m - MAC address
3679
3680	The access attributes are:
3681		a - Any (default)
3682		r - Read-only
3683		o - Write-once
3684		c - Change-default
3685
3686	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3687		Define this to a list (string) to define the ".flags"
3688		envirnoment variable in the default or embedded environment.
3689
3690	- CONFIG_ENV_FLAGS_LIST_STATIC
3691		Define this to a list (string) to define validation that
3692		should be done if an entry is not found in the ".flags"
3693		environment variable.  To override a setting in the static
3694		list, simply add an entry for the same variable name to the
3695		".flags" variable.
3696
3697- CONFIG_ENV_ACCESS_IGNORE_FORCE
3698	If defined, don't allow the -f switch to env set override variable
3699	access flags.
3700
3701- CONFIG_SYS_GENERIC_BOARD
3702	This selects the architecture-generic board system instead of the
3703	architecture-specific board files. It is intended to move boards
3704	to this new framework over time. Defining this will disable the
3705	arch/foo/lib/board.c file and use common/board_f.c and
3706	common/board_r.c instead. To use this option your architecture
3707	must support it (i.e. must define __HAVE_ARCH_GENERIC_BOARD in
3708	its config.mk file). If you find problems enabling this option on
3709	your board please report the problem and send patches!
3710
3711- CONFIG_SYS_SYM_OFFSETS
3712	This is set by architectures that use offsets for link symbols
3713	instead of absolute values. So bss_start is obtained using an
3714	offset _bss_start_ofs from CONFIG_SYS_TEXT_BASE, rather than
3715	directly. You should not need to touch this setting.
3716
3717- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
3718	This is set by OMAP boards for the max time that reset should
3719	be asserted. See doc/README.omap-reset-time for details on how
3720	the value can be calulated on a given board.
3721
3722The following definitions that deal with the placement and management
3723of environment data (variable area); in general, we support the
3724following configurations:
3725
3726- CONFIG_BUILD_ENVCRC:
3727
3728	Builds up envcrc with the target environment so that external utils
3729	may easily extract it and embed it in final U-Boot images.
3730
3731- CONFIG_ENV_IS_IN_FLASH:
3732
3733	Define this if the environment is in flash memory.
3734
3735	a) The environment occupies one whole flash sector, which is
3736	   "embedded" in the text segment with the U-Boot code. This
3737	   happens usually with "bottom boot sector" or "top boot
3738	   sector" type flash chips, which have several smaller
3739	   sectors at the start or the end. For instance, such a
3740	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3741	   such a case you would place the environment in one of the
3742	   4 kB sectors - with U-Boot code before and after it. With
3743	   "top boot sector" type flash chips, you would put the
3744	   environment in one of the last sectors, leaving a gap
3745	   between U-Boot and the environment.
3746
3747	- CONFIG_ENV_OFFSET:
3748
3749	   Offset of environment data (variable area) to the
3750	   beginning of flash memory; for instance, with bottom boot
3751	   type flash chips the second sector can be used: the offset
3752	   for this sector is given here.
3753
3754	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3755
3756	- CONFIG_ENV_ADDR:
3757
3758	   This is just another way to specify the start address of
3759	   the flash sector containing the environment (instead of
3760	   CONFIG_ENV_OFFSET).
3761
3762	- CONFIG_ENV_SECT_SIZE:
3763
3764	   Size of the sector containing the environment.
3765
3766
3767	b) Sometimes flash chips have few, equal sized, BIG sectors.
3768	   In such a case you don't want to spend a whole sector for
3769	   the environment.
3770
3771	- CONFIG_ENV_SIZE:
3772
3773	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3774	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3775	   of this flash sector for the environment. This saves
3776	   memory for the RAM copy of the environment.
3777
3778	   It may also save flash memory if you decide to use this
3779	   when your environment is "embedded" within U-Boot code,
3780	   since then the remainder of the flash sector could be used
3781	   for U-Boot code. It should be pointed out that this is
3782	   STRONGLY DISCOURAGED from a robustness point of view:
3783	   updating the environment in flash makes it always
3784	   necessary to erase the WHOLE sector. If something goes
3785	   wrong before the contents has been restored from a copy in
3786	   RAM, your target system will be dead.
3787
3788	- CONFIG_ENV_ADDR_REDUND
3789	  CONFIG_ENV_SIZE_REDUND
3790
3791	   These settings describe a second storage area used to hold
3792	   a redundant copy of the environment data, so that there is
3793	   a valid backup copy in case there is a power failure during
3794	   a "saveenv" operation.
3795
3796BE CAREFUL! Any changes to the flash layout, and some changes to the
3797source code will make it necessary to adapt <board>/u-boot.lds*
3798accordingly!
3799
3800
3801- CONFIG_ENV_IS_IN_NVRAM:
3802
3803	Define this if you have some non-volatile memory device
3804	(NVRAM, battery buffered SRAM) which you want to use for the
3805	environment.
3806
3807	- CONFIG_ENV_ADDR:
3808	- CONFIG_ENV_SIZE:
3809
3810	  These two #defines are used to determine the memory area you
3811	  want to use for environment. It is assumed that this memory
3812	  can just be read and written to, without any special
3813	  provision.
3814
3815BE CAREFUL! The first access to the environment happens quite early
3816in U-Boot initalization (when we try to get the setting of for the
3817console baudrate). You *MUST* have mapped your NVRAM area then, or
3818U-Boot will hang.
3819
3820Please note that even with NVRAM we still use a copy of the
3821environment in RAM: we could work on NVRAM directly, but we want to
3822keep settings there always unmodified except somebody uses "saveenv"
3823to save the current settings.
3824
3825
3826- CONFIG_ENV_IS_IN_EEPROM:
3827
3828	Use this if you have an EEPROM or similar serial access
3829	device and a driver for it.
3830
3831	- CONFIG_ENV_OFFSET:
3832	- CONFIG_ENV_SIZE:
3833
3834	  These two #defines specify the offset and size of the
3835	  environment area within the total memory of your EEPROM.
3836
3837	- CONFIG_SYS_I2C_EEPROM_ADDR:
3838	  If defined, specified the chip address of the EEPROM device.
3839	  The default address is zero.
3840
3841	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3842	  If defined, the number of bits used to address bytes in a
3843	  single page in the EEPROM device.  A 64 byte page, for example
3844	  would require six bits.
3845
3846	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3847	  If defined, the number of milliseconds to delay between
3848	  page writes.	The default is zero milliseconds.
3849
3850	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3851	  The length in bytes of the EEPROM memory array address.  Note
3852	  that this is NOT the chip address length!
3853
3854	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3855	  EEPROM chips that implement "address overflow" are ones
3856	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3857	  address and the extra bits end up in the "chip address" bit
3858	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3859	  byte chips.
3860
3861	  Note that we consider the length of the address field to
3862	  still be one byte because the extra address bits are hidden
3863	  in the chip address.
3864
3865	- CONFIG_SYS_EEPROM_SIZE:
3866	  The size in bytes of the EEPROM device.
3867
3868	- CONFIG_ENV_EEPROM_IS_ON_I2C
3869	  define this, if you have I2C and SPI activated, and your
3870	  EEPROM, which holds the environment, is on the I2C bus.
3871
3872	- CONFIG_I2C_ENV_EEPROM_BUS
3873	  if you have an Environment on an EEPROM reached over
3874	  I2C muxes, you can define here, how to reach this
3875	  EEPROM. For example:
3876
3877	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
3878
3879	  EEPROM which holds the environment, is reached over
3880	  a pca9547 i2c mux with address 0x70, channel 3.
3881
3882- CONFIG_ENV_IS_IN_DATAFLASH:
3883
3884	Define this if you have a DataFlash memory device which you
3885	want to use for the environment.
3886
3887	- CONFIG_ENV_OFFSET:
3888	- CONFIG_ENV_ADDR:
3889	- CONFIG_ENV_SIZE:
3890
3891	  These three #defines specify the offset and size of the
3892	  environment area within the total memory of your DataFlash placed
3893	  at the specified address.
3894
3895- CONFIG_ENV_IS_IN_REMOTE:
3896
3897	Define this if you have a remote memory space which you
3898	want to use for the local device's environment.
3899
3900	- CONFIG_ENV_ADDR:
3901	- CONFIG_ENV_SIZE:
3902
3903	  These two #defines specify the address and size of the
3904	  environment area within the remote memory space. The
3905	  local device can get the environment from remote memory
3906	  space by SRIO or PCIE links.
3907
3908BE CAREFUL! For some special cases, the local device can not use
3909"saveenv" command. For example, the local device will get the
3910environment stored in a remote NOR flash by SRIO or PCIE link,
3911but it can not erase, write this NOR flash by SRIO or PCIE interface.
3912
3913- CONFIG_ENV_IS_IN_NAND:
3914
3915	Define this if you have a NAND device which you want to use
3916	for the environment.
3917
3918	- CONFIG_ENV_OFFSET:
3919	- CONFIG_ENV_SIZE:
3920
3921	  These two #defines specify the offset and size of the environment
3922	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
3923	  aligned to an erase block boundary.
3924
3925	- CONFIG_ENV_OFFSET_REDUND (optional):
3926
3927	  This setting describes a second storage area of CONFIG_ENV_SIZE
3928	  size used to hold a redundant copy of the environment data, so
3929	  that there is a valid backup copy in case there is a power failure
3930	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
3931	  aligned to an erase block boundary.
3932
3933	- CONFIG_ENV_RANGE (optional):
3934
3935	  Specifies the length of the region in which the environment
3936	  can be written.  This should be a multiple of the NAND device's
3937	  block size.  Specifying a range with more erase blocks than
3938	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
3939	  the range to be avoided.
3940
3941	- CONFIG_ENV_OFFSET_OOB (optional):
3942
3943	  Enables support for dynamically retrieving the offset of the
3944	  environment from block zero's out-of-band data.  The
3945	  "nand env.oob" command can be used to record this offset.
3946	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
3947	  using CONFIG_ENV_OFFSET_OOB.
3948
3949- CONFIG_NAND_ENV_DST
3950
3951	Defines address in RAM to which the nand_spl code should copy the
3952	environment. If redundant environment is used, it will be copied to
3953	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3954
3955- CONFIG_ENV_IS_IN_UBI:
3956
3957	Define this if you have an UBI volume that you want to use for the
3958	environment.  This has the benefit of wear-leveling the environment
3959	accesses, which is important on NAND.
3960
3961	- CONFIG_ENV_UBI_PART:
3962
3963	  Define this to a string that is the mtd partition containing the UBI.
3964
3965	- CONFIG_ENV_UBI_VOLUME:
3966
3967	  Define this to the name of the volume that you want to store the
3968	  environment in.
3969
3970	- CONFIG_ENV_UBI_VOLUME_REDUND:
3971
3972	  Define this to the name of another volume to store a second copy of
3973	  the environment in.  This will enable redundant environments in UBI.
3974	  It is assumed that both volumes are in the same MTD partition.
3975
3976	- CONFIG_UBI_SILENCE_MSG
3977	- CONFIG_UBIFS_SILENCE_MSG
3978
3979	  You will probably want to define these to avoid a really noisy system
3980	  when storing the env in UBI.
3981
3982- CONFIG_ENV_IS_IN_MMC:
3983
3984	Define this if you have an MMC device which you want to use for the
3985	environment.
3986
3987	- CONFIG_SYS_MMC_ENV_DEV:
3988
3989	  Specifies which MMC device the environment is stored in.
3990
3991	- CONFIG_SYS_MMC_ENV_PART (optional):
3992
3993	  Specifies which MMC partition the environment is stored in. If not
3994	  set, defaults to partition 0, the user area. Common values might be
3995	  1 (first MMC boot partition), 2 (second MMC boot partition).
3996
3997	- CONFIG_ENV_OFFSET:
3998	- CONFIG_ENV_SIZE:
3999
4000	  These two #defines specify the offset and size of the environment
4001	  area within the specified MMC device.
4002
4003	  If offset is positive (the usual case), it is treated as relative to
4004	  the start of the MMC partition. If offset is negative, it is treated
4005	  as relative to the end of the MMC partition. This can be useful if
4006	  your board may be fitted with different MMC devices, which have
4007	  different sizes for the MMC partitions, and you always want the
4008	  environment placed at the very end of the partition, to leave the
4009	  maximum possible space before it, to store other data.
4010
4011	  These two values are in units of bytes, but must be aligned to an
4012	  MMC sector boundary.
4013
4014	- CONFIG_ENV_OFFSET_REDUND (optional):
4015
4016	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
4017	  hold a redundant copy of the environment data. This provides a
4018	  valid backup copy in case the other copy is corrupted, e.g. due
4019	  to a power failure during a "saveenv" operation.
4020
4021	  This value may also be positive or negative; this is handled in the
4022	  same way as CONFIG_ENV_OFFSET.
4023
4024	  This value is also in units of bytes, but must also be aligned to
4025	  an MMC sector boundary.
4026
4027	- CONFIG_ENV_SIZE_REDUND (optional):
4028
4029	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
4030	  set. If this value is set, it must be set to the same value as
4031	  CONFIG_ENV_SIZE.
4032
4033- CONFIG_SYS_SPI_INIT_OFFSET
4034
4035	Defines offset to the initial SPI buffer area in DPRAM. The
4036	area is used at an early stage (ROM part) if the environment
4037	is configured to reside in the SPI EEPROM: We need a 520 byte
4038	scratch DPRAM area. It is used between the two initialization
4039	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
4040	to be a good choice since it makes it far enough from the
4041	start of the data area as well as from the stack pointer.
4042
4043Please note that the environment is read-only until the monitor
4044has been relocated to RAM and a RAM copy of the environment has been
4045created; also, when using EEPROM you will have to use getenv_f()
4046until then to read environment variables.
4047
4048The environment is protected by a CRC32 checksum. Before the monitor
4049is relocated into RAM, as a result of a bad CRC you will be working
4050with the compiled-in default environment - *silently*!!! [This is
4051necessary, because the first environment variable we need is the
4052"baudrate" setting for the console - if we have a bad CRC, we don't
4053have any device yet where we could complain.]
4054
4055Note: once the monitor has been relocated, then it will complain if
4056the default environment is used; a new CRC is computed as soon as you
4057use the "saveenv" command to store a valid environment.
4058
4059- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
4060		Echo the inverted Ethernet link state to the fault LED.
4061
4062		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
4063		      also needs to be defined.
4064
4065- CONFIG_SYS_FAULT_MII_ADDR:
4066		MII address of the PHY to check for the Ethernet link state.
4067
4068- CONFIG_NS16550_MIN_FUNCTIONS:
4069		Define this if you desire to only have use of the NS16550_init
4070		and NS16550_putc functions for the serial driver located at
4071		drivers/serial/ns16550.c.  This option is useful for saving
4072		space for already greatly restricted images, including but not
4073		limited to NAND_SPL configurations.
4074
4075- CONFIG_DISPLAY_BOARDINFO
4076		Display information about the board that U-Boot is running on
4077		when U-Boot starts up. The board function checkboard() is called
4078		to do this.
4079
4080- CONFIG_DISPLAY_BOARDINFO_LATE
4081		Similar to the previous option, but display this information
4082		later, once stdio is running and output goes to the LCD, if
4083		present.
4084
4085Low Level (hardware related) configuration options:
4086---------------------------------------------------
4087
4088- CONFIG_SYS_CACHELINE_SIZE:
4089		Cache Line Size of the CPU.
4090
4091- CONFIG_SYS_DEFAULT_IMMR:
4092		Default address of the IMMR after system reset.
4093
4094		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4095		and RPXsuper) to be able to adjust the position of
4096		the IMMR register after a reset.
4097
4098- CONFIG_SYS_CCSRBAR_DEFAULT:
4099		Default (power-on reset) physical address of CCSR on Freescale
4100		PowerPC SOCs.
4101
4102- CONFIG_SYS_CCSRBAR:
4103		Virtual address of CCSR.  On a 32-bit build, this is typically
4104		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4105
4106		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4107		for cross-platform code that uses that macro instead.
4108
4109- CONFIG_SYS_CCSRBAR_PHYS:
4110		Physical address of CCSR.  CCSR can be relocated to a new
4111		physical address, if desired.  In this case, this macro should
4112		be set to that address.	 Otherwise, it should be set to the
4113		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
4114		is typically relocated on 36-bit builds.  It is recommended
4115		that this macro be defined via the _HIGH and _LOW macros:
4116
4117		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4118			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4119
4120- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4121		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
4122		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
4123		used in assembly code, so it must not contain typecasts or
4124		integer size suffixes (e.g. "ULL").
4125
4126- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4127		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
4128		used in assembly code, so it must not contain typecasts or
4129		integer size suffixes (e.g. "ULL").
4130
4131- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
4132		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4133		forced to a value that ensures that CCSR is not relocated.
4134
4135- Floppy Disk Support:
4136		CONFIG_SYS_FDC_DRIVE_NUMBER
4137
4138		the default drive number (default value 0)
4139
4140		CONFIG_SYS_ISA_IO_STRIDE
4141
4142		defines the spacing between FDC chipset registers
4143		(default value 1)
4144
4145		CONFIG_SYS_ISA_IO_OFFSET
4146
4147		defines the offset of register from address. It
4148		depends on which part of the data bus is connected to
4149		the FDC chipset. (default value 0)
4150
4151		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4152		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4153		default value.
4154
4155		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4156		fdc_hw_init() is called at the beginning of the FDC
4157		setup. fdc_hw_init() must be provided by the board
4158		source code. It is used to make hardware dependant
4159		initializations.
4160
4161- CONFIG_IDE_AHB:
4162		Most IDE controllers were designed to be connected with PCI
4163		interface. Only few of them were designed for AHB interface.
4164		When software is doing ATA command and data transfer to
4165		IDE devices through IDE-AHB controller, some additional
4166		registers accessing to these kind of IDE-AHB controller
4167		is requierd.
4168
4169- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4170		DO NOT CHANGE unless you know exactly what you're
4171		doing! (11-4) [MPC8xx/82xx systems only]
4172
4173- CONFIG_SYS_INIT_RAM_ADDR:
4174
4175		Start address of memory area that can be used for
4176		initial data and stack; please note that this must be
4177		writable memory that is working WITHOUT special
4178		initialization, i. e. you CANNOT use normal RAM which
4179		will become available only after programming the
4180		memory controller and running certain initialization
4181		sequences.
4182
4183		U-Boot uses the following memory types:
4184		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4185		- MPC824X: data cache
4186		- PPC4xx:  data cache
4187
4188- CONFIG_SYS_GBL_DATA_OFFSET:
4189
4190		Offset of the initial data structure in the memory
4191		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4192		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4193		data is located at the end of the available space
4194		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4195		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
4196		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4197		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4198
4199	Note:
4200		On the MPC824X (or other systems that use the data
4201		cache for initial memory) the address chosen for
4202		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4203		point to an otherwise UNUSED address space between
4204		the top of RAM and the start of the PCI space.
4205
4206- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4207
4208- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4209
4210- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4211
4212- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4213
4214- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4215
4216- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4217
4218- CONFIG_SYS_OR_TIMING_SDRAM:
4219		SDRAM timing
4220
4221- CONFIG_SYS_MAMR_PTA:
4222		periodic timer for refresh
4223
4224- CONFIG_SYS_DER:	Debug Event Register (37-47)
4225
4226- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4227  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4228  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4229  CONFIG_SYS_BR1_PRELIM:
4230		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4231
4232- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4233  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4234  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4235		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4236
4237- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4238  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4239		Machine Mode Register and Memory Periodic Timer
4240		Prescaler definitions (SDRAM timing)
4241
4242- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4243		enable I2C microcode relocation patch (MPC8xx);
4244		define relocation offset in DPRAM [DSP2]
4245
4246- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4247		enable SMC microcode relocation patch (MPC8xx);
4248		define relocation offset in DPRAM [SMC1]
4249
4250- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4251		enable SPI microcode relocation patch (MPC8xx);
4252		define relocation offset in DPRAM [SCC4]
4253
4254- CONFIG_SYS_USE_OSCCLK:
4255		Use OSCM clock mode on MBX8xx board. Be careful,
4256		wrong setting might damage your board. Read
4257		doc/README.MBX before setting this variable!
4258
4259- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4260		Offset of the bootmode word in DPRAM used by post
4261		(Power On Self Tests). This definition overrides
4262		#define'd default value in commproc.h resp.
4263		cpm_8260.h.
4264
4265- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4266  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4267  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4268  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4269  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4270  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4271  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4272  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4273		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4274
4275- CONFIG_PCI_DISABLE_PCIE:
4276		Disable PCI-Express on systems where it is supported but not
4277		required.
4278
4279- CONFIG_PCI_ENUM_ONLY
4280		Only scan through and get the devices on the busses.
4281		Don't do any setup work, presumably because someone or
4282		something has already done it, and we don't need to do it
4283		a second time.	Useful for platforms that are pre-booted
4284		by coreboot or similar.
4285
4286- CONFIG_PCI_INDIRECT_BRIDGE:
4287		Enable support for indirect PCI bridges.
4288
4289- CONFIG_SYS_SRIO:
4290		Chip has SRIO or not
4291
4292- CONFIG_SRIO1:
4293		Board has SRIO 1 port available
4294
4295- CONFIG_SRIO2:
4296		Board has SRIO 2 port available
4297
4298- CONFIG_SRIO_PCIE_BOOT_MASTER
4299		Board can support master function for Boot from SRIO and PCIE
4300
4301- CONFIG_SYS_SRIOn_MEM_VIRT:
4302		Virtual Address of SRIO port 'n' memory region
4303
4304- CONFIG_SYS_SRIOn_MEM_PHYS:
4305		Physical Address of SRIO port 'n' memory region
4306
4307- CONFIG_SYS_SRIOn_MEM_SIZE:
4308		Size of SRIO port 'n' memory region
4309
4310- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4311		Defined to tell the NAND controller that the NAND chip is using
4312		a 16 bit bus.
4313		Not all NAND drivers use this symbol.
4314		Example of drivers that use it:
4315		- drivers/mtd/nand/ndfc.c
4316		- drivers/mtd/nand/mxc_nand.c
4317
4318- CONFIG_SYS_NDFC_EBC0_CFG
4319		Sets the EBC0_CFG register for the NDFC. If not defined
4320		a default value will be used.
4321
4322- CONFIG_SPD_EEPROM
4323		Get DDR timing information from an I2C EEPROM. Common
4324		with pluggable memory modules such as SODIMMs
4325
4326  SPD_EEPROM_ADDRESS
4327		I2C address of the SPD EEPROM
4328
4329- CONFIG_SYS_SPD_BUS_NUM
4330		If SPD EEPROM is on an I2C bus other than the first
4331		one, specify here. Note that the value must resolve
4332		to something your driver can deal with.
4333
4334- CONFIG_SYS_DDR_RAW_TIMING
4335		Get DDR timing information from other than SPD. Common with
4336		soldered DDR chips onboard without SPD. DDR raw timing
4337		parameters are extracted from datasheet and hard-coded into
4338		header files or board specific files.
4339
4340- CONFIG_FSL_DDR_INTERACTIVE
4341		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4342
4343- CONFIG_SYS_83XX_DDR_USES_CS0
4344		Only for 83xx systems. If specified, then DDR should
4345		be configured using CS0 and CS1 instead of CS2 and CS3.
4346
4347- CONFIG_ETHER_ON_FEC[12]
4348		Define to enable FEC[12] on a 8xx series processor.
4349
4350- CONFIG_FEC[12]_PHY
4351		Define to the hardcoded PHY address which corresponds
4352		to the given FEC; i. e.
4353			#define CONFIG_FEC1_PHY 4
4354		means that the PHY with address 4 is connected to FEC1
4355
4356		When set to -1, means to probe for first available.
4357
4358- CONFIG_FEC[12]_PHY_NORXERR
4359		The PHY does not have a RXERR line (RMII only).
4360		(so program the FEC to ignore it).
4361
4362- CONFIG_RMII
4363		Enable RMII mode for all FECs.
4364		Note that this is a global option, we can't
4365		have one FEC in standard MII mode and another in RMII mode.
4366
4367- CONFIG_CRC32_VERIFY
4368		Add a verify option to the crc32 command.
4369		The syntax is:
4370
4371		=> crc32 -v <address> <count> <crc32>
4372
4373		Where address/count indicate a memory area
4374		and crc32 is the correct crc32 which the
4375		area should have.
4376
4377- CONFIG_LOOPW
4378		Add the "loopw" memory command. This only takes effect if
4379		the memory commands are activated globally (CONFIG_CMD_MEM).
4380
4381- CONFIG_MX_CYCLIC
4382		Add the "mdc" and "mwc" memory commands. These are cyclic
4383		"md/mw" commands.
4384		Examples:
4385
4386		=> mdc.b 10 4 500
4387		This command will print 4 bytes (10,11,12,13) each 500 ms.
4388
4389		=> mwc.l 100 12345678 10
4390		This command will write 12345678 to address 100 all 10 ms.
4391
4392		This only takes effect if the memory commands are activated
4393		globally (CONFIG_CMD_MEM).
4394
4395- CONFIG_SKIP_LOWLEVEL_INIT
4396		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4397		low level initializations (like setting up the memory
4398		controller) are omitted and/or U-Boot does not
4399		relocate itself into RAM.
4400
4401		Normally this variable MUST NOT be defined. The only
4402		exception is when U-Boot is loaded (to RAM) by some
4403		other boot loader or by a debugger which performs
4404		these initializations itself.
4405
4406- CONFIG_SPL_BUILD
4407		Modifies the behaviour of start.S when compiling a loader
4408		that is executed before the actual U-Boot. E.g. when
4409		compiling a NAND SPL.
4410
4411- CONFIG_TPL_BUILD
4412		Modifies the behaviour of start.S  when compiling a loader
4413		that is executed after the SPL and before the actual U-Boot.
4414		It is loaded by the SPL.
4415
4416- CONFIG_SYS_MPC85XX_NO_RESETVEC
4417		Only for 85xx systems. If this variable is specified, the section
4418		.resetvec is not kept and the section .bootpg is placed in the
4419		previous 4k of the .text section.
4420
4421- CONFIG_ARCH_MAP_SYSMEM
4422		Generally U-Boot (and in particular the md command) uses
4423		effective address. It is therefore not necessary to regard
4424		U-Boot address as virtual addresses that need to be translated
4425		to physical addresses. However, sandbox requires this, since
4426		it maintains its own little RAM buffer which contains all
4427		addressable memory. This option causes some memory accesses
4428		to be mapped through map_sysmem() / unmap_sysmem().
4429
4430- CONFIG_USE_ARCH_MEMCPY
4431  CONFIG_USE_ARCH_MEMSET
4432		If these options are used a optimized version of memcpy/memset will
4433		be used if available. These functions may be faster under some
4434		conditions but may increase the binary size.
4435
4436- CONFIG_X86_RESET_VECTOR
4437		If defined, the x86 reset vector code is included. This is not
4438		needed when U-Boot is running from Coreboot.
4439
4440- CONFIG_SYS_MPUCLK
4441		Defines the MPU clock speed (in MHz).
4442
4443		NOTE : currently only supported on AM335x platforms.
4444
4445- CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
4446		Enables the RTC32K OSC on AM33xx based plattforms
4447
4448Freescale QE/FMAN Firmware Support:
4449-----------------------------------
4450
4451The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4452loading of "firmware", which is encoded in the QE firmware binary format.
4453This firmware often needs to be loaded during U-Boot booting, so macros
4454are used to identify the storage device (NOR flash, SPI, etc) and the address
4455within that device.
4456
4457- CONFIG_SYS_QE_FMAN_FW_ADDR
4458	The address in the storage device where the firmware is located.  The
4459	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4460	is also specified.
4461
4462- CONFIG_SYS_QE_FMAN_FW_LENGTH
4463	The maximum possible size of the firmware.  The firmware binary format
4464	has a field that specifies the actual size of the firmware, but it
4465	might not be possible to read any part of the firmware unless some
4466	local storage is allocated to hold the entire firmware first.
4467
4468- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4469	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4470	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4471	virtual address in NOR flash.
4472
4473- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4474	Specifies that QE/FMAN firmware is located in NAND flash.
4475	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4476
4477- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4478	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4479	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4480
4481- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
4482	Specifies that QE/FMAN firmware is located on the primary SPI
4483	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4484
4485- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4486	Specifies that QE/FMAN firmware is located in the remote (master)
4487	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4488	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4489	window->master inbound window->master LAW->the ucode address in
4490	master's memory space.
4491
4492Building the Software:
4493======================
4494
4495Building U-Boot has been tested in several native build environments
4496and in many different cross environments. Of course we cannot support
4497all possibly existing versions of cross development tools in all
4498(potentially obsolete) versions. In case of tool chain problems we
4499recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4500which is extensively used to build and test U-Boot.
4501
4502If you are not using a native environment, it is assumed that you
4503have GNU cross compiling tools available in your path. In this case,
4504you must set the environment variable CROSS_COMPILE in your shell.
4505Note that no changes to the Makefile or any other source files are
4506necessary. For example using the ELDK on a 4xx CPU, please enter:
4507
4508	$ CROSS_COMPILE=ppc_4xx-
4509	$ export CROSS_COMPILE
4510
4511Note: If you wish to generate Windows versions of the utilities in
4512      the tools directory you can use the MinGW toolchain
4513      (http://www.mingw.org).  Set your HOST tools to the MinGW
4514      toolchain and execute 'make tools'.  For example:
4515
4516       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4517
4518      Binaries such as tools/mkimage.exe will be created which can
4519      be executed on computers running Windows.
4520
4521U-Boot is intended to be simple to build. After installing the
4522sources you must configure U-Boot for one specific board type. This
4523is done by typing:
4524
4525	make NAME_config
4526
4527where "NAME_config" is the name of one of the existing configu-
4528rations; see boards.cfg for supported names.
4529
4530Note: for some board special configuration names may exist; check if
4531      additional information is available from the board vendor; for
4532      instance, the TQM823L systems are available without (standard)
4533      or with LCD support. You can select such additional "features"
4534      when choosing the configuration, i. e.
4535
4536      make TQM823L_config
4537	- will configure for a plain TQM823L, i. e. no LCD support
4538
4539      make TQM823L_LCD_config
4540	- will configure for a TQM823L with U-Boot console on LCD
4541
4542      etc.
4543
4544
4545Finally, type "make all", and you should get some working U-Boot
4546images ready for download to / installation on your system:
4547
4548- "u-boot.bin" is a raw binary image
4549- "u-boot" is an image in ELF binary format
4550- "u-boot.srec" is in Motorola S-Record format
4551
4552By default the build is performed locally and the objects are saved
4553in the source directory. One of the two methods can be used to change
4554this behavior and build U-Boot to some external directory:
4555
45561. Add O= to the make command line invocations:
4557
4558	make O=/tmp/build distclean
4559	make O=/tmp/build NAME_config
4560	make O=/tmp/build all
4561
45622. Set environment variable BUILD_DIR to point to the desired location:
4563
4564	export BUILD_DIR=/tmp/build
4565	make distclean
4566	make NAME_config
4567	make all
4568
4569Note that the command line "O=" setting overrides the BUILD_DIR environment
4570variable.
4571
4572
4573Please be aware that the Makefiles assume you are using GNU make, so
4574for instance on NetBSD you might need to use "gmake" instead of
4575native "make".
4576
4577
4578If the system board that you have is not listed, then you will need
4579to port U-Boot to your hardware platform. To do this, follow these
4580steps:
4581
45821.  Add a new configuration option for your board to the toplevel
4583    "boards.cfg" file, using the existing entries as examples.
4584    Follow the instructions there to keep the boards in order.
45852.  Create a new directory to hold your board specific code. Add any
4586    files you need. In your board directory, you will need at least
4587    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
45883.  Create a new configuration file "include/configs/<board>.h" for
4589    your board
45903.  If you're porting U-Boot to a new CPU, then also create a new
4591    directory to hold your CPU specific code. Add any files you need.
45924.  Run "make <board>_config" with your new name.
45935.  Type "make", and you should get a working "u-boot.srec" file
4594    to be installed on your target system.
45956.  Debug and solve any problems that might arise.
4596    [Of course, this last step is much harder than it sounds.]
4597
4598
4599Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4600==============================================================
4601
4602If you have modified U-Boot sources (for instance added a new board
4603or support for new devices, a new CPU, etc.) you are expected to
4604provide feedback to the other developers. The feedback normally takes
4605the form of a "patch", i. e. a context diff against a certain (latest
4606official or latest in the git repository) version of U-Boot sources.
4607
4608But before you submit such a patch, please verify that your modifi-
4609cation did not break existing code. At least make sure that *ALL* of
4610the supported boards compile WITHOUT ANY compiler warnings. To do so,
4611just run the "MAKEALL" script, which will configure and build U-Boot
4612for ALL supported system. Be warned, this will take a while. You can
4613select which (cross) compiler to use by passing a `CROSS_COMPILE'
4614environment variable to the script, i. e. to use the ELDK cross tools
4615you can type
4616
4617	CROSS_COMPILE=ppc_8xx- MAKEALL
4618
4619or to build on a native PowerPC system you can type
4620
4621	CROSS_COMPILE=' ' MAKEALL
4622
4623When using the MAKEALL script, the default behaviour is to build
4624U-Boot in the source directory. This location can be changed by
4625setting the BUILD_DIR environment variable. Also, for each target
4626built, the MAKEALL script saves two log files (<target>.ERR and
4627<target>.MAKEALL) in the <source dir>/LOG directory. This default
4628location can be changed by setting the MAKEALL_LOGDIR environment
4629variable. For example:
4630
4631	export BUILD_DIR=/tmp/build
4632	export MAKEALL_LOGDIR=/tmp/log
4633	CROSS_COMPILE=ppc_8xx- MAKEALL
4634
4635With the above settings build objects are saved in the /tmp/build,
4636log files are saved in the /tmp/log and the source tree remains clean
4637during the whole build process.
4638
4639
4640See also "U-Boot Porting Guide" below.
4641
4642
4643Monitor Commands - Overview:
4644============================
4645
4646go	- start application at address 'addr'
4647run	- run commands in an environment variable
4648bootm	- boot application image from memory
4649bootp	- boot image via network using BootP/TFTP protocol
4650bootz   - boot zImage from memory
4651tftpboot- boot image via network using TFTP protocol
4652	       and env variables "ipaddr" and "serverip"
4653	       (and eventually "gatewayip")
4654tftpput - upload a file via network using TFTP protocol
4655rarpboot- boot image via network using RARP/TFTP protocol
4656diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4657loads	- load S-Record file over serial line
4658loadb	- load binary file over serial line (kermit mode)
4659md	- memory display
4660mm	- memory modify (auto-incrementing)
4661nm	- memory modify (constant address)
4662mw	- memory write (fill)
4663cp	- memory copy
4664cmp	- memory compare
4665crc32	- checksum calculation
4666i2c	- I2C sub-system
4667sspi	- SPI utility commands
4668base	- print or set address offset
4669printenv- print environment variables
4670setenv	- set environment variables
4671saveenv - save environment variables to persistent storage
4672protect - enable or disable FLASH write protection
4673erase	- erase FLASH memory
4674flinfo	- print FLASH memory information
4675nand	- NAND memory operations (see doc/README.nand)
4676bdinfo	- print Board Info structure
4677iminfo	- print header information for application image
4678coninfo - print console devices and informations
4679ide	- IDE sub-system
4680loop	- infinite loop on address range
4681loopw	- infinite write loop on address range
4682mtest	- simple RAM test
4683icache	- enable or disable instruction cache
4684dcache	- enable or disable data cache
4685reset	- Perform RESET of the CPU
4686echo	- echo args to console
4687version - print monitor version
4688help	- print online help
4689?	- alias for 'help'
4690
4691
4692Monitor Commands - Detailed Description:
4693========================================
4694
4695TODO.
4696
4697For now: just type "help <command>".
4698
4699
4700Environment Variables:
4701======================
4702
4703U-Boot supports user configuration using Environment Variables which
4704can be made persistent by saving to Flash memory.
4705
4706Environment Variables are set using "setenv", printed using
4707"printenv", and saved to Flash using "saveenv". Using "setenv"
4708without a value can be used to delete a variable from the
4709environment. As long as you don't save the environment you are
4710working with an in-memory copy. In case the Flash area containing the
4711environment is erased by accident, a default environment is provided.
4712
4713Some configuration options can be set using Environment Variables.
4714
4715List of environment variables (most likely not complete):
4716
4717  baudrate	- see CONFIG_BAUDRATE
4718
4719  bootdelay	- see CONFIG_BOOTDELAY
4720
4721  bootcmd	- see CONFIG_BOOTCOMMAND
4722
4723  bootargs	- Boot arguments when booting an RTOS image
4724
4725  bootfile	- Name of the image to load with TFTP
4726
4727  bootm_low	- Memory range available for image processing in the bootm
4728		  command can be restricted. This variable is given as
4729		  a hexadecimal number and defines lowest address allowed
4730		  for use by the bootm command. See also "bootm_size"
4731		  environment variable. Address defined by "bootm_low" is
4732		  also the base of the initial memory mapping for the Linux
4733		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
4734		  bootm_mapsize.
4735
4736  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
4737		  This variable is given as a hexadecimal number and it
4738		  defines the size of the memory region starting at base
4739		  address bootm_low that is accessible by the Linux kernel
4740		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
4741		  as the default value if it is defined, and bootm_size is
4742		  used otherwise.
4743
4744  bootm_size	- Memory range available for image processing in the bootm
4745		  command can be restricted. This variable is given as
4746		  a hexadecimal number and defines the size of the region
4747		  allowed for use by the bootm command. See also "bootm_low"
4748		  environment variable.
4749
4750  updatefile	- Location of the software update file on a TFTP server, used
4751		  by the automatic software update feature. Please refer to
4752		  documentation in doc/README.update for more details.
4753
4754  autoload	- if set to "no" (any string beginning with 'n'),
4755		  "bootp" will just load perform a lookup of the
4756		  configuration from the BOOTP server, but not try to
4757		  load any image using TFTP
4758
4759  autostart	- if set to "yes", an image loaded using the "bootp",
4760		  "rarpboot", "tftpboot" or "diskboot" commands will
4761		  be automatically started (by internally calling
4762		  "bootm")
4763
4764		  If set to "no", a standalone image passed to the
4765		  "bootm" command will be copied to the load address
4766		  (and eventually uncompressed), but NOT be started.
4767		  This can be used to load and uncompress arbitrary
4768		  data.
4769
4770  fdt_high	- if set this restricts the maximum address that the
4771		  flattened device tree will be copied into upon boot.
4772		  For example, if you have a system with 1 GB memory
4773		  at physical address 0x10000000, while Linux kernel
4774		  only recognizes the first 704 MB as low memory, you
4775		  may need to set fdt_high as 0x3C000000 to have the
4776		  device tree blob be copied to the maximum address
4777		  of the 704 MB low memory, so that Linux kernel can
4778		  access it during the boot procedure.
4779
4780		  If this is set to the special value 0xFFFFFFFF then
4781		  the fdt will not be copied at all on boot.  For this
4782		  to work it must reside in writable memory, have
4783		  sufficient padding on the end of it for u-boot to
4784		  add the information it needs into it, and the memory
4785		  must be accessible by the kernel.
4786
4787  fdtcontroladdr- if set this is the address of the control flattened
4788		  device tree used by U-Boot when CONFIG_OF_CONTROL is
4789		  defined.
4790
4791  i2cfast	- (PPC405GP|PPC405EP only)
4792		  if set to 'y' configures Linux I2C driver for fast
4793		  mode (400kHZ). This environment variable is used in
4794		  initialization code. So, for changes to be effective
4795		  it must be saved and board must be reset.
4796
4797  initrd_high	- restrict positioning of initrd images:
4798		  If this variable is not set, initrd images will be
4799		  copied to the highest possible address in RAM; this
4800		  is usually what you want since it allows for
4801		  maximum initrd size. If for some reason you want to
4802		  make sure that the initrd image is loaded below the
4803		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
4804		  variable to a value of "no" or "off" or "0".
4805		  Alternatively, you can set it to a maximum upper
4806		  address to use (U-Boot will still check that it
4807		  does not overwrite the U-Boot stack and data).
4808
4809		  For instance, when you have a system with 16 MB
4810		  RAM, and want to reserve 4 MB from use by Linux,
4811		  you can do this by adding "mem=12M" to the value of
4812		  the "bootargs" variable. However, now you must make
4813		  sure that the initrd image is placed in the first
4814		  12 MB as well - this can be done with
4815
4816		  setenv initrd_high 00c00000
4817
4818		  If you set initrd_high to 0xFFFFFFFF, this is an
4819		  indication to U-Boot that all addresses are legal
4820		  for the Linux kernel, including addresses in flash
4821		  memory. In this case U-Boot will NOT COPY the
4822		  ramdisk at all. This may be useful to reduce the
4823		  boot time on your system, but requires that this
4824		  feature is supported by your Linux kernel.
4825
4826  ipaddr	- IP address; needed for tftpboot command
4827
4828  loadaddr	- Default load address for commands like "bootp",
4829		  "rarpboot", "tftpboot", "loadb" or "diskboot"
4830
4831  loads_echo	- see CONFIG_LOADS_ECHO
4832
4833  serverip	- TFTP server IP address; needed for tftpboot command
4834
4835  bootretry	- see CONFIG_BOOT_RETRY_TIME
4836
4837  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
4838
4839  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
4840
4841  ethprime	- controls which interface is used first.
4842
4843  ethact	- controls which interface is currently active.
4844		  For example you can do the following
4845
4846		  => setenv ethact FEC
4847		  => ping 192.168.0.1 # traffic sent on FEC
4848		  => setenv ethact SCC
4849		  => ping 10.0.0.1 # traffic sent on SCC
4850
4851  ethrotate	- When set to "no" U-Boot does not go through all
4852		  available network interfaces.
4853		  It just stays at the currently selected interface.
4854
4855  netretry	- When set to "no" each network operation will
4856		  either succeed or fail without retrying.
4857		  When set to "once" the network operation will
4858		  fail when all the available network interfaces
4859		  are tried once without success.
4860		  Useful on scripts which control the retry operation
4861		  themselves.
4862
4863  npe_ucode	- set load address for the NPE microcode
4864
4865  silent_linux  - If set then linux will be told to boot silently, by
4866		  changing the console to be empty. If "yes" it will be
4867		  made silent. If "no" it will not be made silent. If
4868		  unset, then it will be made silent if the U-Boot console
4869		  is silent.
4870
4871  tftpsrcport	- If this is set, the value is used for TFTP's
4872		  UDP source port.
4873
4874  tftpdstport	- If this is set, the value is used for TFTP's UDP
4875		  destination port instead of the Well Know Port 69.
4876
4877  tftpblocksize - Block size to use for TFTP transfers; if not set,
4878		  we use the TFTP server's default block size
4879
4880  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
4881		  seconds, minimum value is 1000 = 1 second). Defines
4882		  when a packet is considered to be lost so it has to
4883		  be retransmitted. The default is 5000 = 5 seconds.
4884		  Lowering this value may make downloads succeed
4885		  faster in networks with high packet loss rates or
4886		  with unreliable TFTP servers.
4887
4888  vlan		- When set to a value < 4095 the traffic over
4889		  Ethernet is encapsulated/received over 802.1q
4890		  VLAN tagged frames.
4891
4892The following image location variables contain the location of images
4893used in booting. The "Image" column gives the role of the image and is
4894not an environment variable name. The other columns are environment
4895variable names. "File Name" gives the name of the file on a TFTP
4896server, "RAM Address" gives the location in RAM the image will be
4897loaded to, and "Flash Location" gives the image's address in NOR
4898flash or offset in NAND flash.
4899
4900*Note* - these variables don't have to be defined for all boards, some
4901boards currenlty use other variables for these purposes, and some
4902boards use these variables for other purposes.
4903
4904Image		    File Name	     RAM Address       Flash Location
4905-----		    ---------	     -----------       --------------
4906u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
4907Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
4908device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
4909ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
4910
4911The following environment variables may be used and automatically
4912updated by the network boot commands ("bootp" and "rarpboot"),
4913depending the information provided by your boot server:
4914
4915  bootfile	- see above
4916  dnsip		- IP address of your Domain Name Server
4917  dnsip2	- IP address of your secondary Domain Name Server
4918  gatewayip	- IP address of the Gateway (Router) to use
4919  hostname	- Target hostname
4920  ipaddr	- see above
4921  netmask	- Subnet Mask
4922  rootpath	- Pathname of the root filesystem on the NFS server
4923  serverip	- see above
4924
4925
4926There are two special Environment Variables:
4927
4928  serial#	- contains hardware identification information such
4929		  as type string and/or serial number
4930  ethaddr	- Ethernet address
4931
4932These variables can be set only once (usually during manufacturing of
4933the board). U-Boot refuses to delete or overwrite these variables
4934once they have been set once.
4935
4936
4937Further special Environment Variables:
4938
4939  ver		- Contains the U-Boot version string as printed
4940		  with the "version" command. This variable is
4941		  readonly (see CONFIG_VERSION_VARIABLE).
4942
4943
4944Please note that changes to some configuration parameters may take
4945only effect after the next boot (yes, that's just like Windoze :-).
4946
4947
4948Callback functions for environment variables:
4949---------------------------------------------
4950
4951For some environment variables, the behavior of u-boot needs to change
4952when their values are changed.  This functionailty allows functions to
4953be associated with arbitrary variables.  On creation, overwrite, or
4954deletion, the callback will provide the opportunity for some side
4955effect to happen or for the change to be rejected.
4956
4957The callbacks are named and associated with a function using the
4958U_BOOT_ENV_CALLBACK macro in your board or driver code.
4959
4960These callbacks are associated with variables in one of two ways.  The
4961static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
4962in the board configuration to a string that defines a list of
4963associations.  The list must be in the following format:
4964
4965	entry = variable_name[:callback_name]
4966	list = entry[,list]
4967
4968If the callback name is not specified, then the callback is deleted.
4969Spaces are also allowed anywhere in the list.
4970
4971Callbacks can also be associated by defining the ".callbacks" variable
4972with the same list format above.  Any association in ".callbacks" will
4973override any association in the static list. You can define
4974CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
4975".callbacks" envirnoment variable in the default or embedded environment.
4976
4977
4978Command Line Parsing:
4979=====================
4980
4981There are two different command line parsers available with U-Boot:
4982the old "simple" one, and the much more powerful "hush" shell:
4983
4984Old, simple command line parser:
4985--------------------------------
4986
4987- supports environment variables (through setenv / saveenv commands)
4988- several commands on one line, separated by ';'
4989- variable substitution using "... ${name} ..." syntax
4990- special characters ('$', ';') can be escaped by prefixing with '\',
4991  for example:
4992	setenv bootcmd bootm \${address}
4993- You can also escape text by enclosing in single apostrophes, for example:
4994	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
4995
4996Hush shell:
4997-----------
4998
4999- similar to Bourne shell, with control structures like
5000  if...then...else...fi, for...do...done; while...do...done,
5001  until...do...done, ...
5002- supports environment ("global") variables (through setenv / saveenv
5003  commands) and local shell variables (through standard shell syntax
5004  "name=value"); only environment variables can be used with "run"
5005  command
5006
5007General rules:
5008--------------
5009
5010(1) If a command line (or an environment variable executed by a "run"
5011    command) contains several commands separated by semicolon, and
5012    one of these commands fails, then the remaining commands will be
5013    executed anyway.
5014
5015(2) If you execute several variables with one call to run (i. e.
5016    calling run with a list of variables as arguments), any failing
5017    command will cause "run" to terminate, i. e. the remaining
5018    variables are not executed.
5019
5020Note for Redundant Ethernet Interfaces:
5021=======================================
5022
5023Some boards come with redundant Ethernet interfaces; U-Boot supports
5024such configurations and is capable of automatic selection of a
5025"working" interface when needed. MAC assignment works as follows:
5026
5027Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
5028MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
5029"eth1addr" (=>eth1), "eth2addr", ...
5030
5031If the network interface stores some valid MAC address (for instance
5032in SROM), this is used as default address if there is NO correspon-
5033ding setting in the environment; if the corresponding environment
5034variable is set, this overrides the settings in the card; that means:
5035
5036o If the SROM has a valid MAC address, and there is no address in the
5037  environment, the SROM's address is used.
5038
5039o If there is no valid address in the SROM, and a definition in the
5040  environment exists, then the value from the environment variable is
5041  used.
5042
5043o If both the SROM and the environment contain a MAC address, and
5044  both addresses are the same, this MAC address is used.
5045
5046o If both the SROM and the environment contain a MAC address, and the
5047  addresses differ, the value from the environment is used and a
5048  warning is printed.
5049
5050o If neither SROM nor the environment contain a MAC address, an error
5051  is raised.
5052
5053If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
5054will be programmed into hardware as part of the initialization process.	 This
5055may be skipped by setting the appropriate 'ethmacskip' environment variable.
5056The naming convention is as follows:
5057"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
5058
5059Image Formats:
5060==============
5061
5062U-Boot is capable of booting (and performing other auxiliary operations on)
5063images in two formats:
5064
5065New uImage format (FIT)
5066-----------------------
5067
5068Flexible and powerful format based on Flattened Image Tree -- FIT (similar
5069to Flattened Device Tree). It allows the use of images with multiple
5070components (several kernels, ramdisks, etc.), with contents protected by
5071SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
5072
5073
5074Old uImage format
5075-----------------
5076
5077Old image format is based on binary files which can be basically anything,
5078preceded by a special header; see the definitions in include/image.h for
5079details; basically, the header defines the following image properties:
5080
5081* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
5082  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
5083  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
5084  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
5085  INTEGRITY).
5086* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
5087  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
5088  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
5089* Compression Type (uncompressed, gzip, bzip2)
5090* Load Address
5091* Entry Point
5092* Image Name
5093* Image Timestamp
5094
5095The header is marked by a special Magic Number, and both the header
5096and the data portions of the image are secured against corruption by
5097CRC32 checksums.
5098
5099
5100Linux Support:
5101==============
5102
5103Although U-Boot should support any OS or standalone application
5104easily, the main focus has always been on Linux during the design of
5105U-Boot.
5106
5107U-Boot includes many features that so far have been part of some
5108special "boot loader" code within the Linux kernel. Also, any
5109"initrd" images to be used are no longer part of one big Linux image;
5110instead, kernel and "initrd" are separate images. This implementation
5111serves several purposes:
5112
5113- the same features can be used for other OS or standalone
5114  applications (for instance: using compressed images to reduce the
5115  Flash memory footprint)
5116
5117- it becomes much easier to port new Linux kernel versions because
5118  lots of low-level, hardware dependent stuff are done by U-Boot
5119
5120- the same Linux kernel image can now be used with different "initrd"
5121  images; of course this also means that different kernel images can
5122  be run with the same "initrd". This makes testing easier (you don't
5123  have to build a new "zImage.initrd" Linux image when you just
5124  change a file in your "initrd"). Also, a field-upgrade of the
5125  software is easier now.
5126
5127
5128Linux HOWTO:
5129============
5130
5131Porting Linux to U-Boot based systems:
5132---------------------------------------
5133
5134U-Boot cannot save you from doing all the necessary modifications to
5135configure the Linux device drivers for use with your target hardware
5136(no, we don't intend to provide a full virtual machine interface to
5137Linux :-).
5138
5139But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
5140
5141Just make sure your machine specific header file (for instance
5142include/asm-ppc/tqm8xx.h) includes the same definition of the Board
5143Information structure as we define in include/asm-<arch>/u-boot.h,
5144and make sure that your definition of IMAP_ADDR uses the same value
5145as your U-Boot configuration in CONFIG_SYS_IMMR.
5146
5147
5148Configuring the Linux kernel:
5149-----------------------------
5150
5151No specific requirements for U-Boot. Make sure you have some root
5152device (initial ramdisk, NFS) for your target system.
5153
5154
5155Building a Linux Image:
5156-----------------------
5157
5158With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5159not used. If you use recent kernel source, a new build target
5160"uImage" will exist which automatically builds an image usable by
5161U-Boot. Most older kernels also have support for a "pImage" target,
5162which was introduced for our predecessor project PPCBoot and uses a
5163100% compatible format.
5164
5165Example:
5166
5167	make TQM850L_config
5168	make oldconfig
5169	make dep
5170	make uImage
5171
5172The "uImage" build target uses a special tool (in 'tools/mkimage') to
5173encapsulate a compressed Linux kernel image with header	 information,
5174CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5175
5176* build a standard "vmlinux" kernel image (in ELF binary format):
5177
5178* convert the kernel into a raw binary image:
5179
5180	${CROSS_COMPILE}-objcopy -O binary \
5181				 -R .note -R .comment \
5182				 -S vmlinux linux.bin
5183
5184* compress the binary image:
5185
5186	gzip -9 linux.bin
5187
5188* package compressed binary image for U-Boot:
5189
5190	mkimage -A ppc -O linux -T kernel -C gzip \
5191		-a 0 -e 0 -n "Linux Kernel Image" \
5192		-d linux.bin.gz uImage
5193
5194
5195The "mkimage" tool can also be used to create ramdisk images for use
5196with U-Boot, either separated from the Linux kernel image, or
5197combined into one file. "mkimage" encapsulates the images with a 64
5198byte header containing information about target architecture,
5199operating system, image type, compression method, entry points, time
5200stamp, CRC32 checksums, etc.
5201
5202"mkimage" can be called in two ways: to verify existing images and
5203print the header information, or to build new images.
5204
5205In the first form (with "-l" option) mkimage lists the information
5206contained in the header of an existing U-Boot image; this includes
5207checksum verification:
5208
5209	tools/mkimage -l image
5210	  -l ==> list image header information
5211
5212The second form (with "-d" option) is used to build a U-Boot image
5213from a "data file" which is used as image payload:
5214
5215	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5216		      -n name -d data_file image
5217	  -A ==> set architecture to 'arch'
5218	  -O ==> set operating system to 'os'
5219	  -T ==> set image type to 'type'
5220	  -C ==> set compression type 'comp'
5221	  -a ==> set load address to 'addr' (hex)
5222	  -e ==> set entry point to 'ep' (hex)
5223	  -n ==> set image name to 'name'
5224	  -d ==> use image data from 'datafile'
5225
5226Right now, all Linux kernels for PowerPC systems use the same load
5227address (0x00000000), but the entry point address depends on the
5228kernel version:
5229
5230- 2.2.x kernels have the entry point at 0x0000000C,
5231- 2.3.x and later kernels have the entry point at 0x00000000.
5232
5233So a typical call to build a U-Boot image would read:
5234
5235	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5236	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5237	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5238	> examples/uImage.TQM850L
5239	Image Name:   2.4.4 kernel for TQM850L
5240	Created:      Wed Jul 19 02:34:59 2000
5241	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5242	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5243	Load Address: 0x00000000
5244	Entry Point:  0x00000000
5245
5246To verify the contents of the image (or check for corruption):
5247
5248	-> tools/mkimage -l examples/uImage.TQM850L
5249	Image Name:   2.4.4 kernel for TQM850L
5250	Created:      Wed Jul 19 02:34:59 2000
5251	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5252	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5253	Load Address: 0x00000000
5254	Entry Point:  0x00000000
5255
5256NOTE: for embedded systems where boot time is critical you can trade
5257speed for memory and install an UNCOMPRESSED image instead: this
5258needs more space in Flash, but boots much faster since it does not
5259need to be uncompressed:
5260
5261	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5262	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5263	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5264	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5265	> examples/uImage.TQM850L-uncompressed
5266	Image Name:   2.4.4 kernel for TQM850L
5267	Created:      Wed Jul 19 02:34:59 2000
5268	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5269	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5270	Load Address: 0x00000000
5271	Entry Point:  0x00000000
5272
5273
5274Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5275when your kernel is intended to use an initial ramdisk:
5276
5277	-> tools/mkimage -n 'Simple Ramdisk Image' \
5278	> -A ppc -O linux -T ramdisk -C gzip \
5279	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5280	Image Name:   Simple Ramdisk Image
5281	Created:      Wed Jan 12 14:01:50 2000
5282	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5283	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5284	Load Address: 0x00000000
5285	Entry Point:  0x00000000
5286
5287The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
5288option performs the converse operation of the mkimage's second form (the "-d"
5289option). Given an image built by mkimage, the dumpimage extracts a "data file"
5290from the image:
5291
5292	tools/dumpimage -i image -p position data_file
5293	  -i ==> extract from the 'image' a specific 'data_file', \
5294	   indexed by 'position'
5295
5296
5297Installing a Linux Image:
5298-------------------------
5299
5300To downloading a U-Boot image over the serial (console) interface,
5301you must convert the image to S-Record format:
5302
5303	objcopy -I binary -O srec examples/image examples/image.srec
5304
5305The 'objcopy' does not understand the information in the U-Boot
5306image header, so the resulting S-Record file will be relative to
5307address 0x00000000. To load it to a given address, you need to
5308specify the target address as 'offset' parameter with the 'loads'
5309command.
5310
5311Example: install the image to address 0x40100000 (which on the
5312TQM8xxL is in the first Flash bank):
5313
5314	=> erase 40100000 401FFFFF
5315
5316	.......... done
5317	Erased 8 sectors
5318
5319	=> loads 40100000
5320	## Ready for S-Record download ...
5321	~>examples/image.srec
5322	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5323	...
5324	15989 15990 15991 15992
5325	[file transfer complete]
5326	[connected]
5327	## Start Addr = 0x00000000
5328
5329
5330You can check the success of the download using the 'iminfo' command;
5331this includes a checksum verification so you can be sure no data
5332corruption happened:
5333
5334	=> imi 40100000
5335
5336	## Checking Image at 40100000 ...
5337	   Image Name:	 2.2.13 for initrd on TQM850L
5338	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5339	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5340	   Load Address: 00000000
5341	   Entry Point:	 0000000c
5342	   Verifying Checksum ... OK
5343
5344
5345Boot Linux:
5346-----------
5347
5348The "bootm" command is used to boot an application that is stored in
5349memory (RAM or Flash). In case of a Linux kernel image, the contents
5350of the "bootargs" environment variable is passed to the kernel as
5351parameters. You can check and modify this variable using the
5352"printenv" and "setenv" commands:
5353
5354
5355	=> printenv bootargs
5356	bootargs=root=/dev/ram
5357
5358	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5359
5360	=> printenv bootargs
5361	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5362
5363	=> bootm 40020000
5364	## Booting Linux kernel at 40020000 ...
5365	   Image Name:	 2.2.13 for NFS on TQM850L
5366	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5367	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5368	   Load Address: 00000000
5369	   Entry Point:	 0000000c
5370	   Verifying Checksum ... OK
5371	   Uncompressing Kernel Image ... OK
5372	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
5373	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5374	time_init: decrementer frequency = 187500000/60
5375	Calibrating delay loop... 49.77 BogoMIPS
5376	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5377	...
5378
5379If you want to boot a Linux kernel with initial RAM disk, you pass
5380the memory addresses of both the kernel and the initrd image (PPBCOOT
5381format!) to the "bootm" command:
5382
5383	=> imi 40100000 40200000
5384
5385	## Checking Image at 40100000 ...
5386	   Image Name:	 2.2.13 for initrd on TQM850L
5387	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5388	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5389	   Load Address: 00000000
5390	   Entry Point:	 0000000c
5391	   Verifying Checksum ... OK
5392
5393	## Checking Image at 40200000 ...
5394	   Image Name:	 Simple Ramdisk Image
5395	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5396	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5397	   Load Address: 00000000
5398	   Entry Point:	 00000000
5399	   Verifying Checksum ... OK
5400
5401	=> bootm 40100000 40200000
5402	## Booting Linux kernel at 40100000 ...
5403	   Image Name:	 2.2.13 for initrd on TQM850L
5404	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5405	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5406	   Load Address: 00000000
5407	   Entry Point:	 0000000c
5408	   Verifying Checksum ... OK
5409	   Uncompressing Kernel Image ... OK
5410	## Loading RAMDisk Image at 40200000 ...
5411	   Image Name:	 Simple Ramdisk Image
5412	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5413	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5414	   Load Address: 00000000
5415	   Entry Point:	 00000000
5416	   Verifying Checksum ... OK
5417	   Loading Ramdisk ... OK
5418	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
5419	Boot arguments: root=/dev/ram
5420	time_init: decrementer frequency = 187500000/60
5421	Calibrating delay loop... 49.77 BogoMIPS
5422	...
5423	RAMDISK: Compressed image found at block 0
5424	VFS: Mounted root (ext2 filesystem).
5425
5426	bash#
5427
5428Boot Linux and pass a flat device tree:
5429-----------
5430
5431First, U-Boot must be compiled with the appropriate defines. See the section
5432titled "Linux Kernel Interface" above for a more in depth explanation. The
5433following is an example of how to start a kernel and pass an updated
5434flat device tree:
5435
5436=> print oftaddr
5437oftaddr=0x300000
5438=> print oft
5439oft=oftrees/mpc8540ads.dtb
5440=> tftp $oftaddr $oft
5441Speed: 1000, full duplex
5442Using TSEC0 device
5443TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5444Filename 'oftrees/mpc8540ads.dtb'.
5445Load address: 0x300000
5446Loading: #
5447done
5448Bytes transferred = 4106 (100a hex)
5449=> tftp $loadaddr $bootfile
5450Speed: 1000, full duplex
5451Using TSEC0 device
5452TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5453Filename 'uImage'.
5454Load address: 0x200000
5455Loading:############
5456done
5457Bytes transferred = 1029407 (fb51f hex)
5458=> print loadaddr
5459loadaddr=200000
5460=> print oftaddr
5461oftaddr=0x300000
5462=> bootm $loadaddr - $oftaddr
5463## Booting image at 00200000 ...
5464   Image Name:	 Linux-2.6.17-dirty
5465   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5466   Data Size:	 1029343 Bytes = 1005.2 kB
5467   Load Address: 00000000
5468   Entry Point:	 00000000
5469   Verifying Checksum ... OK
5470   Uncompressing Kernel Image ... OK
5471Booting using flat device tree at 0x300000
5472Using MPC85xx ADS machine description
5473Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5474[snip]
5475
5476
5477More About U-Boot Image Types:
5478------------------------------
5479
5480U-Boot supports the following image types:
5481
5482   "Standalone Programs" are directly runnable in the environment
5483	provided by U-Boot; it is expected that (if they behave
5484	well) you can continue to work in U-Boot after return from
5485	the Standalone Program.
5486   "OS Kernel Images" are usually images of some Embedded OS which
5487	will take over control completely. Usually these programs
5488	will install their own set of exception handlers, device
5489	drivers, set up the MMU, etc. - this means, that you cannot
5490	expect to re-enter U-Boot except by resetting the CPU.
5491   "RAMDisk Images" are more or less just data blocks, and their
5492	parameters (address, size) are passed to an OS kernel that is
5493	being started.
5494   "Multi-File Images" contain several images, typically an OS
5495	(Linux) kernel image and one or more data images like
5496	RAMDisks. This construct is useful for instance when you want
5497	to boot over the network using BOOTP etc., where the boot
5498	server provides just a single image file, but you want to get
5499	for instance an OS kernel and a RAMDisk image.
5500
5501	"Multi-File Images" start with a list of image sizes, each
5502	image size (in bytes) specified by an "uint32_t" in network
5503	byte order. This list is terminated by an "(uint32_t)0".
5504	Immediately after the terminating 0 follow the images, one by
5505	one, all aligned on "uint32_t" boundaries (size rounded up to
5506	a multiple of 4 bytes).
5507
5508   "Firmware Images" are binary images containing firmware (like
5509	U-Boot or FPGA images) which usually will be programmed to
5510	flash memory.
5511
5512   "Script files" are command sequences that will be executed by
5513	U-Boot's command interpreter; this feature is especially
5514	useful when you configure U-Boot to use a real shell (hush)
5515	as command interpreter.
5516
5517Booting the Linux zImage:
5518-------------------------
5519
5520On some platforms, it's possible to boot Linux zImage. This is done
5521using the "bootz" command. The syntax of "bootz" command is the same
5522as the syntax of "bootm" command.
5523
5524Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5525kernel with raw initrd images. The syntax is slightly different, the
5526address of the initrd must be augmented by it's size, in the following
5527format: "<initrd addres>:<initrd size>".
5528
5529
5530Standalone HOWTO:
5531=================
5532
5533One of the features of U-Boot is that you can dynamically load and
5534run "standalone" applications, which can use some resources of
5535U-Boot like console I/O functions or interrupt services.
5536
5537Two simple examples are included with the sources:
5538
5539"Hello World" Demo:
5540-------------------
5541
5542'examples/hello_world.c' contains a small "Hello World" Demo
5543application; it is automatically compiled when you build U-Boot.
5544It's configured to run at address 0x00040004, so you can play with it
5545like that:
5546
5547	=> loads
5548	## Ready for S-Record download ...
5549	~>examples/hello_world.srec
5550	1 2 3 4 5 6 7 8 9 10 11 ...
5551	[file transfer complete]
5552	[connected]
5553	## Start Addr = 0x00040004
5554
5555	=> go 40004 Hello World! This is a test.
5556	## Starting application at 0x00040004 ...
5557	Hello World
5558	argc = 7
5559	argv[0] = "40004"
5560	argv[1] = "Hello"
5561	argv[2] = "World!"
5562	argv[3] = "This"
5563	argv[4] = "is"
5564	argv[5] = "a"
5565	argv[6] = "test."
5566	argv[7] = "<NULL>"
5567	Hit any key to exit ...
5568
5569	## Application terminated, rc = 0x0
5570
5571Another example, which demonstrates how to register a CPM interrupt
5572handler with the U-Boot code, can be found in 'examples/timer.c'.
5573Here, a CPM timer is set up to generate an interrupt every second.
5574The interrupt service routine is trivial, just printing a '.'
5575character, but this is just a demo program. The application can be
5576controlled by the following keys:
5577
5578	? - print current values og the CPM Timer registers
5579	b - enable interrupts and start timer
5580	e - stop timer and disable interrupts
5581	q - quit application
5582
5583	=> loads
5584	## Ready for S-Record download ...
5585	~>examples/timer.srec
5586	1 2 3 4 5 6 7 8 9 10 11 ...
5587	[file transfer complete]
5588	[connected]
5589	## Start Addr = 0x00040004
5590
5591	=> go 40004
5592	## Starting application at 0x00040004 ...
5593	TIMERS=0xfff00980
5594	Using timer 1
5595	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5596
5597Hit 'b':
5598	[q, b, e, ?] Set interval 1000000 us
5599	Enabling timer
5600Hit '?':
5601	[q, b, e, ?] ........
5602	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5603Hit '?':
5604	[q, b, e, ?] .
5605	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5606Hit '?':
5607	[q, b, e, ?] .
5608	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
5609Hit '?':
5610	[q, b, e, ?] .
5611	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
5612Hit 'e':
5613	[q, b, e, ?] ...Stopping timer
5614Hit 'q':
5615	[q, b, e, ?] ## Application terminated, rc = 0x0
5616
5617
5618Minicom warning:
5619================
5620
5621Over time, many people have reported problems when trying to use the
5622"minicom" terminal emulation program for serial download. I (wd)
5623consider minicom to be broken, and recommend not to use it. Under
5624Unix, I recommend to use C-Kermit for general purpose use (and
5625especially for kermit binary protocol download ("loadb" command), and
5626use "cu" for S-Record download ("loads" command).  See
5627http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
5628for help with kermit.
5629
5630
5631Nevertheless, if you absolutely want to use it try adding this
5632configuration to your "File transfer protocols" section:
5633
5634	   Name	   Program			Name U/D FullScr IO-Red. Multi
5635	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5636	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5637
5638
5639NetBSD Notes:
5640=============
5641
5642Starting at version 0.9.2, U-Boot supports NetBSD both as host
5643(build U-Boot) and target system (boots NetBSD/mpc8xx).
5644
5645Building requires a cross environment; it is known to work on
5646NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5647need gmake since the Makefiles are not compatible with BSD make).
5648Note that the cross-powerpc package does not install include files;
5649attempting to build U-Boot will fail because <machine/ansi.h> is
5650missing.  This file has to be installed and patched manually:
5651
5652	# cd /usr/pkg/cross/powerpc-netbsd/include
5653	# mkdir powerpc
5654	# ln -s powerpc machine
5655	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5656	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5657
5658Native builds *don't* work due to incompatibilities between native
5659and U-Boot include files.
5660
5661Booting assumes that (the first part of) the image booted is a
5662stage-2 loader which in turn loads and then invokes the kernel
5663proper. Loader sources will eventually appear in the NetBSD source
5664tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5665meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5666
5667
5668Implementation Internals:
5669=========================
5670
5671The following is not intended to be a complete description of every
5672implementation detail. However, it should help to understand the
5673inner workings of U-Boot and make it easier to port it to custom
5674hardware.
5675
5676
5677Initial Stack, Global Data:
5678---------------------------
5679
5680The implementation of U-Boot is complicated by the fact that U-Boot
5681starts running out of ROM (flash memory), usually without access to
5682system RAM (because the memory controller is not initialized yet).
5683This means that we don't have writable Data or BSS segments, and BSS
5684is not initialized as zero. To be able to get a C environment working
5685at all, we have to allocate at least a minimal stack. Implementation
5686options for this are defined and restricted by the CPU used: Some CPU
5687models provide on-chip memory (like the IMMR area on MPC8xx and
5688MPC826x processors), on others (parts of) the data cache can be
5689locked as (mis-) used as memory, etc.
5690
5691	Chris Hallinan posted a good summary of these issues to the
5692	U-Boot mailing list:
5693
5694	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
5695	From: "Chris Hallinan" <clh@net1plus.com>
5696	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
5697	...
5698
5699	Correct me if I'm wrong, folks, but the way I understand it
5700	is this: Using DCACHE as initial RAM for Stack, etc, does not
5701	require any physical RAM backing up the cache. The cleverness
5702	is that the cache is being used as a temporary supply of
5703	necessary storage before the SDRAM controller is setup. It's
5704	beyond the scope of this list to explain the details, but you
5705	can see how this works by studying the cache architecture and
5706	operation in the architecture and processor-specific manuals.
5707
5708	OCM is On Chip Memory, which I believe the 405GP has 4K. It
5709	is another option for the system designer to use as an
5710	initial stack/RAM area prior to SDRAM being available. Either
5711	option should work for you. Using CS 4 should be fine if your
5712	board designers haven't used it for something that would
5713	cause you grief during the initial boot! It is frequently not
5714	used.
5715
5716	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
5717	with your processor/board/system design. The default value
5718	you will find in any recent u-boot distribution in
5719	walnut.h should work for you. I'd set it to a value larger
5720	than your SDRAM module. If you have a 64MB SDRAM module, set
5721	it above 400_0000. Just make sure your board has no resources
5722	that are supposed to respond to that address! That code in
5723	start.S has been around a while and should work as is when
5724	you get the config right.
5725
5726	-Chris Hallinan
5727	DS4.COM, Inc.
5728
5729It is essential to remember this, since it has some impact on the C
5730code for the initialization procedures:
5731
5732* Initialized global data (data segment) is read-only. Do not attempt
5733  to write it.
5734
5735* Do not use any uninitialized global data (or implicitely initialized
5736  as zero data - BSS segment) at all - this is undefined, initiali-
5737  zation is performed later (when relocating to RAM).
5738
5739* Stack space is very limited. Avoid big data buffers or things like
5740  that.
5741
5742Having only the stack as writable memory limits means we cannot use
5743normal global data to share information beween the code. But it
5744turned out that the implementation of U-Boot can be greatly
5745simplified by making a global data structure (gd_t) available to all
5746functions. We could pass a pointer to this data as argument to _all_
5747functions, but this would bloat the code. Instead we use a feature of
5748the GCC compiler (Global Register Variables) to share the data: we
5749place a pointer (gd) to the global data into a register which we
5750reserve for this purpose.
5751
5752When choosing a register for such a purpose we are restricted by the
5753relevant  (E)ABI  specifications for the current architecture, and by
5754GCC's implementation.
5755
5756For PowerPC, the following registers have specific use:
5757	R1:	stack pointer
5758	R2:	reserved for system use
5759	R3-R4:	parameter passing and return values
5760	R5-R10: parameter passing
5761	R13:	small data area pointer
5762	R30:	GOT pointer
5763	R31:	frame pointer
5764
5765	(U-Boot also uses R12 as internal GOT pointer. r12
5766	is a volatile register so r12 needs to be reset when
5767	going back and forth between asm and C)
5768
5769    ==> U-Boot will use R2 to hold a pointer to the global data
5770
5771    Note: on PPC, we could use a static initializer (since the
5772    address of the global data structure is known at compile time),
5773    but it turned out that reserving a register results in somewhat
5774    smaller code - although the code savings are not that big (on
5775    average for all boards 752 bytes for the whole U-Boot image,
5776    624 text + 127 data).
5777
5778On Blackfin, the normal C ABI (except for P3) is followed as documented here:
5779	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
5780
5781    ==> U-Boot will use P3 to hold a pointer to the global data
5782
5783On ARM, the following registers are used:
5784
5785	R0:	function argument word/integer result
5786	R1-R3:	function argument word
5787	R9:	platform specific
5788	R10:	stack limit (used only if stack checking is enabled)
5789	R11:	argument (frame) pointer
5790	R12:	temporary workspace
5791	R13:	stack pointer
5792	R14:	link register
5793	R15:	program counter
5794
5795    ==> U-Boot will use R9 to hold a pointer to the global data
5796
5797    Note: on ARM, only R_ARM_RELATIVE relocations are supported.
5798
5799On Nios II, the ABI is documented here:
5800	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
5801
5802    ==> U-Boot will use gp to hold a pointer to the global data
5803
5804    Note: on Nios II, we give "-G0" option to gcc and don't use gp
5805    to access small data sections, so gp is free.
5806
5807On NDS32, the following registers are used:
5808
5809	R0-R1:	argument/return
5810	R2-R5:	argument
5811	R15:	temporary register for assembler
5812	R16:	trampoline register
5813	R28:	frame pointer (FP)
5814	R29:	global pointer (GP)
5815	R30:	link register (LP)
5816	R31:	stack pointer (SP)
5817	PC:	program counter (PC)
5818
5819    ==> U-Boot will use R10 to hold a pointer to the global data
5820
5821NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
5822or current versions of GCC may "optimize" the code too much.
5823
5824Memory Management:
5825------------------
5826
5827U-Boot runs in system state and uses physical addresses, i.e. the
5828MMU is not used either for address mapping nor for memory protection.
5829
5830The available memory is mapped to fixed addresses using the memory
5831controller. In this process, a contiguous block is formed for each
5832memory type (Flash, SDRAM, SRAM), even when it consists of several
5833physical memory banks.
5834
5835U-Boot is installed in the first 128 kB of the first Flash bank (on
5836TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
5837booting and sizing and initializing DRAM, the code relocates itself
5838to the upper end of DRAM. Immediately below the U-Boot code some
5839memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
5840configuration setting]. Below that, a structure with global Board
5841Info data is placed, followed by the stack (growing downward).
5842
5843Additionally, some exception handler code is copied to the low 8 kB
5844of DRAM (0x00000000 ... 0x00001FFF).
5845
5846So a typical memory configuration with 16 MB of DRAM could look like
5847this:
5848
5849	0x0000 0000	Exception Vector code
5850	      :
5851	0x0000 1FFF
5852	0x0000 2000	Free for Application Use
5853	      :
5854	      :
5855
5856	      :
5857	      :
5858	0x00FB FF20	Monitor Stack (Growing downward)
5859	0x00FB FFAC	Board Info Data and permanent copy of global data
5860	0x00FC 0000	Malloc Arena
5861	      :
5862	0x00FD FFFF
5863	0x00FE 0000	RAM Copy of Monitor Code
5864	...		eventually: LCD or video framebuffer
5865	...		eventually: pRAM (Protected RAM - unchanged by reset)
5866	0x00FF FFFF	[End of RAM]
5867
5868
5869System Initialization:
5870----------------------
5871
5872In the reset configuration, U-Boot starts at the reset entry point
5873(on most PowerPC systems at address 0x00000100). Because of the reset
5874configuration for CS0# this is a mirror of the onboard Flash memory.
5875To be able to re-map memory U-Boot then jumps to its link address.
5876To be able to implement the initialization code in C, a (small!)
5877initial stack is set up in the internal Dual Ported RAM (in case CPUs
5878which provide such a feature like MPC8xx or MPC8260), or in a locked
5879part of the data cache. After that, U-Boot initializes the CPU core,
5880the caches and the SIU.
5881
5882Next, all (potentially) available memory banks are mapped using a
5883preliminary mapping. For example, we put them on 512 MB boundaries
5884(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
5885on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
5886programmed for SDRAM access. Using the temporary configuration, a
5887simple memory test is run that determines the size of the SDRAM
5888banks.
5889
5890When there is more than one SDRAM bank, and the banks are of
5891different size, the largest is mapped first. For equal size, the first
5892bank (CS2#) is mapped first. The first mapping is always for address
58930x00000000, with any additional banks following immediately to create
5894contiguous memory starting from 0.
5895
5896Then, the monitor installs itself at the upper end of the SDRAM area
5897and allocates memory for use by malloc() and for the global Board
5898Info data; also, the exception vector code is copied to the low RAM
5899pages, and the final stack is set up.
5900
5901Only after this relocation will you have a "normal" C environment;
5902until that you are restricted in several ways, mostly because you are
5903running from ROM, and because the code will have to be relocated to a
5904new address in RAM.
5905
5906
5907U-Boot Porting Guide:
5908----------------------
5909
5910[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
5911list, October 2002]
5912
5913
5914int main(int argc, char *argv[])
5915{
5916	sighandler_t no_more_time;
5917
5918	signal(SIGALRM, no_more_time);
5919	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
5920
5921	if (available_money > available_manpower) {
5922		Pay consultant to port U-Boot;
5923		return 0;
5924	}
5925
5926	Download latest U-Boot source;
5927
5928	Subscribe to u-boot mailing list;
5929
5930	if (clueless)
5931		email("Hi, I am new to U-Boot, how do I get started?");
5932
5933	while (learning) {
5934		Read the README file in the top level directory;
5935		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
5936		Read applicable doc/*.README;
5937		Read the source, Luke;
5938		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
5939	}
5940
5941	if (available_money > toLocalCurrency ($2500))
5942		Buy a BDI3000;
5943	else
5944		Add a lot of aggravation and time;
5945
5946	if (a similar board exists) {	/* hopefully... */
5947		cp -a board/<similar> board/<myboard>
5948		cp include/configs/<similar>.h include/configs/<myboard>.h
5949	} else {
5950		Create your own board support subdirectory;
5951		Create your own board include/configs/<myboard>.h file;
5952	}
5953	Edit new board/<myboard> files
5954	Edit new include/configs/<myboard>.h
5955
5956	while (!accepted) {
5957		while (!running) {
5958			do {
5959				Add / modify source code;
5960			} until (compiles);
5961			Debug;
5962			if (clueless)
5963				email("Hi, I am having problems...");
5964		}
5965		Send patch file to the U-Boot email list;
5966		if (reasonable critiques)
5967			Incorporate improvements from email list code review;
5968		else
5969			Defend code as written;
5970	}
5971
5972	return 0;
5973}
5974
5975void no_more_time (int sig)
5976{
5977      hire_a_guru();
5978}
5979
5980
5981Coding Standards:
5982-----------------
5983
5984All contributions to U-Boot should conform to the Linux kernel
5985coding style; see the file "Documentation/CodingStyle" and the script
5986"scripts/Lindent" in your Linux kernel source directory.
5987
5988Source files originating from a different project (for example the
5989MTD subsystem) are generally exempt from these guidelines and are not
5990reformated to ease subsequent migration to newer versions of those
5991sources.
5992
5993Please note that U-Boot is implemented in C (and to some small parts in
5994Assembler); no C++ is used, so please do not use C++ style comments (//)
5995in your code.
5996
5997Please also stick to the following formatting rules:
5998- remove any trailing white space
5999- use TAB characters for indentation and vertical alignment, not spaces
6000- make sure NOT to use DOS '\r\n' line feeds
6001- do not add more than 2 consecutive empty lines to source files
6002- do not add trailing empty lines to source files
6003
6004Submissions which do not conform to the standards may be returned
6005with a request to reformat the changes.
6006
6007
6008Submitting Patches:
6009-------------------
6010
6011Since the number of patches for U-Boot is growing, we need to
6012establish some rules. Submissions which do not conform to these rules
6013may be rejected, even when they contain important and valuable stuff.
6014
6015Please see http://www.denx.de/wiki/U-Boot/Patches for details.
6016
6017Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
6018see http://lists.denx.de/mailman/listinfo/u-boot
6019
6020When you send a patch, please include the following information with
6021it:
6022
6023* For bug fixes: a description of the bug and how your patch fixes
6024  this bug. Please try to include a way of demonstrating that the
6025  patch actually fixes something.
6026
6027* For new features: a description of the feature and your
6028  implementation.
6029
6030* A CHANGELOG entry as plaintext (separate from the patch)
6031
6032* For major contributions, your entry to the CREDITS file
6033
6034* When you add support for a new board, don't forget to add a
6035  maintainer e-mail address to the boards.cfg file, too.
6036
6037* If your patch adds new configuration options, don't forget to
6038  document these in the README file.
6039
6040* The patch itself. If you are using git (which is *strongly*
6041  recommended) you can easily generate the patch using the
6042  "git format-patch". If you then use "git send-email" to send it to
6043  the U-Boot mailing list, you will avoid most of the common problems
6044  with some other mail clients.
6045
6046  If you cannot use git, use "diff -purN OLD NEW". If your version of
6047  diff does not support these options, then get the latest version of
6048  GNU diff.
6049
6050  The current directory when running this command shall be the parent
6051  directory of the U-Boot source tree (i. e. please make sure that
6052  your patch includes sufficient directory information for the
6053  affected files).
6054
6055  We prefer patches as plain text. MIME attachments are discouraged,
6056  and compressed attachments must not be used.
6057
6058* If one logical set of modifications affects or creates several
6059  files, all these changes shall be submitted in a SINGLE patch file.
6060
6061* Changesets that contain different, unrelated modifications shall be
6062  submitted as SEPARATE patches, one patch per changeset.
6063
6064
6065Notes:
6066
6067* Before sending the patch, run the MAKEALL script on your patched
6068  source tree and make sure that no errors or warnings are reported
6069  for any of the boards.
6070
6071* Keep your modifications to the necessary minimum: A patch
6072  containing several unrelated changes or arbitrary reformats will be
6073  returned with a request to re-formatting / split it.
6074
6075* If you modify existing code, make sure that your new code does not
6076  add to the memory footprint of the code ;-) Small is beautiful!
6077  When adding new features, these should compile conditionally only
6078  (using #ifdef), and the resulting code with the new feature
6079  disabled must not need more memory than the old code without your
6080  modification.
6081
6082* Remember that there is a size limit of 100 kB per message on the
6083  u-boot mailing list. Bigger patches will be moderated. If they are
6084  reasonable and not too big, they will be acknowledged. But patches
6085  bigger than the size limit should be avoided.
6086