xref: /rk3399_rockchip-uboot/README (revision 4e5b1bd0dff216b00d7ce9a5201dfe173805a06c)
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      /pxa		Files specific to Intel XScale PXA CPUs
145      /sa1100		Files specific to Intel StrongARM SA1100 CPUs
146    /lib		Architecture specific library files
147  /avr32		Files generic to AVR32 architecture
148    /cpu		CPU specific files
149    /lib		Architecture specific library files
150  /blackfin		Files generic to Analog Devices Blackfin architecture
151    /cpu		CPU specific files
152    /lib		Architecture specific library files
153  /m68k			Files generic to m68k architecture
154    /cpu		CPU specific files
155      /mcf52x2		Files specific to Freescale ColdFire MCF52x2 CPUs
156      /mcf5227x		Files specific to Freescale ColdFire MCF5227x CPUs
157      /mcf532x		Files specific to Freescale ColdFire MCF5329 CPUs
158      /mcf5445x		Files specific to Freescale ColdFire MCF5445x CPUs
159      /mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
160    /lib		Architecture specific library files
161  /microblaze		Files generic to microblaze architecture
162    /cpu		CPU specific files
163    /lib		Architecture specific library files
164  /mips			Files generic to MIPS architecture
165    /cpu		CPU specific files
166      /mips32		Files specific to MIPS32 CPUs
167      /xburst		Files specific to Ingenic XBurst CPUs
168    /lib		Architecture specific library files
169  /nds32		Files generic to NDS32 architecture
170    /cpu		CPU specific files
171      /n1213		Files specific to Andes Technology N1213 CPUs
172    /lib		Architecture specific library files
173  /nios2		Files generic to Altera NIOS2 architecture
174    /cpu		CPU specific files
175    /lib		Architecture specific library files
176  /openrisc		Files generic to OpenRISC architecture
177    /cpu		CPU specific files
178    /lib		Architecture specific library files
179  /powerpc		Files generic to PowerPC architecture
180    /cpu		CPU specific files
181      /74xx_7xx		Files specific to Freescale MPC74xx and 7xx CPUs
182      /mpc5xx		Files specific to Freescale MPC5xx CPUs
183      /mpc5xxx		Files specific to Freescale MPC5xxx CPUs
184      /mpc8xx		Files specific to Freescale MPC8xx CPUs
185      /mpc824x		Files specific to Freescale MPC824x CPUs
186      /mpc8260		Files specific to Freescale MPC8260 CPUs
187      /mpc85xx		Files specific to Freescale MPC85xx CPUs
188      /ppc4xx		Files specific to AMCC PowerPC 4xx CPUs
189    /lib		Architecture specific library files
190  /sh			Files generic to SH architecture
191    /cpu		CPU specific files
192      /sh2		Files specific to sh2 CPUs
193      /sh3		Files specific to sh3 CPUs
194      /sh4		Files specific to sh4 CPUs
195    /lib		Architecture specific library files
196  /sparc		Files generic to SPARC architecture
197    /cpu		CPU specific files
198      /leon2		Files specific to Gaisler LEON2 SPARC CPU
199      /leon3		Files specific to Gaisler LEON3 SPARC CPU
200    /lib		Architecture specific library files
201  /x86			Files generic to x86 architecture
202    /cpu		CPU specific files
203    /lib		Architecture specific library files
204/api			Machine/arch independent API for external apps
205/board			Board dependent files
206/common			Misc architecture independent functions
207/disk			Code for disk drive partition handling
208/doc			Documentation (don't expect too much)
209/drivers		Commonly used device drivers
210/dts			Contains Makefile for building internal U-Boot fdt.
211/examples		Example code for standalone applications, etc.
212/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
213/include		Header Files
214/lib			Files generic to all architectures
215  /libfdt		Library files to support flattened device trees
216  /lzma			Library files to support LZMA decompression
217  /lzo			Library files to support LZO decompression
218/net			Networking code
219/post			Power On Self Test
220/spl			Secondary Program Loader framework
221/tools			Tools to build S-Record or U-Boot images, etc.
222
223Software Configuration:
224=======================
225
226Configuration is usually done using C preprocessor defines; the
227rationale behind that is to avoid dead code whenever possible.
228
229There are two classes of configuration variables:
230
231* Configuration _OPTIONS_:
232  These are selectable by the user and have names beginning with
233  "CONFIG_".
234
235* Configuration _SETTINGS_:
236  These depend on the hardware etc. and should not be meddled with if
237  you don't know what you're doing; they have names beginning with
238  "CONFIG_SYS_".
239
240Later we will add a configuration tool - probably similar to or even
241identical to what's used for the Linux kernel. Right now, we have to
242do the configuration by hand, which means creating some symbolic
243links and editing some configuration files. We use the TQM8xxL boards
244as an example here.
245
246
247Selection of Processor Architecture and Board Type:
248---------------------------------------------------
249
250For all supported boards there are ready-to-use default
251configurations available; just type "make <board_name>_config".
252
253Example: For a TQM823L module type:
254
255	cd u-boot
256	make TQM823L_config
257
258For the Cogent platform, you need to specify the CPU type as well;
259e.g. "make cogent_mpc8xx_config". And also configure the cogent
260directory according to the instructions in cogent/README.
261
262
263Configuration Options:
264----------------------
265
266Configuration depends on the combination of board and CPU type; all
267such information is kept in a configuration file
268"include/configs/<board_name>.h".
269
270Example: For a TQM823L module, all configuration settings are in
271"include/configs/TQM823L.h".
272
273
274Many of the options are named exactly as the corresponding Linux
275kernel configuration options. The intention is to make it easier to
276build a config tool - later.
277
278
279The following options need to be configured:
280
281- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
282
283- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
284
285- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
286		Define exactly one, e.g. CONFIG_ATSTK1002
287
288- CPU Module Type: (if CONFIG_COGENT is defined)
289		Define exactly one of
290		CONFIG_CMA286_60_OLD
291--- FIXME --- not tested yet:
292		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
293		CONFIG_CMA287_23, CONFIG_CMA287_50
294
295- Motherboard Type: (if CONFIG_COGENT is defined)
296		Define exactly one of
297		CONFIG_CMA101, CONFIG_CMA102
298
299- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
300		Define one or more of
301		CONFIG_CMA302
302
303- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
304		Define one or more of
305		CONFIG_LCD_HEARTBEAT	- update a character position on
306					  the LCD display every second with
307					  a "rotator" |\-/|\-/
308
309- Board flavour: (if CONFIG_MPC8260ADS is defined)
310		CONFIG_ADSTYPE
311		Possible values are:
312			CONFIG_SYS_8260ADS	- original MPC8260ADS
313			CONFIG_SYS_8266ADS	- MPC8266ADS
314			CONFIG_SYS_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
315			CONFIG_SYS_8272ADS	- MPC8272ADS
316
317- Marvell Family Member
318		CONFIG_SYS_MVFS		- define it if you want to enable
319					  multiple fs option at one time
320					  for marvell soc family
321
322- MPC824X Family Member (if CONFIG_MPC824X is defined)
323		Define exactly one of
324		CONFIG_MPC8240, CONFIG_MPC8245
325
326- 8xx CPU Options: (if using an MPC8xx CPU)
327		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
328					  get_gclk_freq() cannot work
329					  e.g. if there is no 32KHz
330					  reference PIT/RTC clock
331		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
332					  or XTAL/EXTAL)
333
334- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
335		CONFIG_SYS_8xx_CPUCLK_MIN
336		CONFIG_SYS_8xx_CPUCLK_MAX
337		CONFIG_8xx_CPUCLK_DEFAULT
338			See doc/README.MPC866
339
340		CONFIG_SYS_MEASURE_CPUCLK
341
342		Define this to measure the actual CPU clock instead
343		of relying on the correctness of the configured
344		values. Mostly useful for board bringup to make sure
345		the PLL is locked at the intended frequency. Note
346		that this requires a (stable) reference clock (32 kHz
347		RTC clock or CONFIG_SYS_8XX_XIN)
348
349		CONFIG_SYS_DELAYED_ICACHE
350
351		Define this option if you want to enable the
352		ICache only when Code runs from RAM.
353
354- 85xx CPU Options:
355		CONFIG_SYS_PPC64
356
357		Specifies that the core is a 64-bit PowerPC implementation (implements
358		the "64" category of the Power ISA). This is necessary for ePAPR
359		compliance, among other possible reasons.
360
361		CONFIG_SYS_FSL_TBCLK_DIV
362
363		Defines the core time base clock divider ratio compared to the
364		system clock.  On most PQ3 devices this is 8, on newer QorIQ
365		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
366
367		CONFIG_SYS_FSL_PCIE_COMPAT
368
369		Defines the string to utilize when trying to match PCIe device
370		tree nodes for the given platform.
371
372		CONFIG_SYS_PPC_E500_DEBUG_TLB
373
374		Enables a temporary TLB entry to be used during boot to work
375		around limitations in e500v1 and e500v2 external debugger
376		support. This reduces the portions of the boot code where
377		breakpoints and single stepping do not work.  The value of this
378		symbol should be set to the TLB1 entry to be used for this
379		purpose.
380
381		CONFIG_SYS_FSL_ERRATUM_A004510
382
383		Enables a workaround for erratum A004510.  If set,
384		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
385		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
386
387		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
388		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
389
390		Defines one or two SoC revisions (low 8 bits of SVR)
391		for which the A004510 workaround should be applied.
392
393		The rest of SVR is either not relevant to the decision
394		of whether the erratum is present (e.g. p2040 versus
395		p2041) or is implied by the build target, which controls
396		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
397
398		See Freescale App Note 4493 for more information about
399		this erratum.
400
401		CONFIG_A003399_NOR_WORKAROUND
402		Enables a workaround for IFC erratum A003399. It is only
403		requred during NOR boot.
404
405		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
406
407		This is the value to write into CCSR offset 0x18600
408		according to the A004510 workaround.
409
410		CONFIG_SYS_FSL_DSP_DDR_ADDR
411		This value denotes start offset of DDR memory which is
412		connected exclusively to the DSP cores.
413
414		CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
415		This value denotes start offset of M2 memory
416		which is directly connected to the DSP core.
417
418		CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
419		This value denotes start offset of M3 memory which is directly
420		connected to the DSP core.
421
422		CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
423		This value denotes start offset of DSP CCSR space.
424
425		CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
426		Single Source Clock is clocking mode present in some of FSL SoC's.
427		In this mode, a single differential clock is used to supply
428		clocks to the sysclock, ddrclock and usbclock.
429
430- Generic CPU options:
431		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
432
433		Defines the endianess of the CPU. Implementation of those
434		values is arch specific.
435
436		CONFIG_SYS_FSL_DDR
437		Freescale DDR driver in use. This type of DDR controller is
438		found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
439		SoCs.
440
441		CONFIG_SYS_FSL_DDR_ADDR
442		Freescale DDR memory-mapped register base.
443
444		CONFIG_SYS_FSL_DDR_EMU
445		Specify emulator support for DDR. Some DDR features such as
446		deskew training are not available.
447
448		CONFIG_SYS_FSL_DDRC_GEN1
449		Freescale DDR1 controller.
450
451		CONFIG_SYS_FSL_DDRC_GEN2
452		Freescale DDR2 controller.
453
454		CONFIG_SYS_FSL_DDRC_GEN3
455		Freescale DDR3 controller.
456
457		CONFIG_SYS_FSL_DDRC_ARM_GEN3
458		Freescale DDR3 controller for ARM-based SoCs.
459
460		CONFIG_SYS_FSL_DDR1
461		Board config to use DDR1. It can be enabled for SoCs with
462		Freescale DDR1 or DDR2 controllers, depending on the board
463		implemetation.
464
465		CONFIG_SYS_FSL_DDR2
466		Board config to use DDR2. It can be eanbeld for SoCs with
467		Freescale DDR2 or DDR3 controllers, depending on the board
468		implementation.
469
470		CONFIG_SYS_FSL_DDR3
471		Board config to use DDR3. It can be enabled for SoCs with
472		Freescale DDR3 controllers.
473
474		CONFIG_SYS_FSL_IFC_BE
475		Defines the IFC controller register space as Big Endian
476
477		CONFIG_SYS_FSL_IFC_LE
478		Defines the IFC controller register space as Little Endian
479
480		CONFIG_SYS_FSL_PBL_PBI
481		It enables addition of RCW (Power on reset configuration) in built image.
482		Please refer doc/README.pblimage for more details
483
484		CONFIG_SYS_FSL_PBL_RCW
485		It adds PBI(pre-boot instructions) commands in u-boot build image.
486		PBI commands can be used to configure SoC before it starts the execution.
487		Please refer doc/README.pblimage for more details
488
489		CONFIG_SYS_FSL_DDR_BE
490		Defines the DDR controller register space as Big Endian
491
492		CONFIG_SYS_FSL_DDR_LE
493		Defines the DDR controller register space as Little Endian
494
495- Intel Monahans options:
496		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
497
498		Defines the Monahans run mode to oscillator
499		ratio. Valid values are 8, 16, 24, 31. The core
500		frequency is this value multiplied by 13 MHz.
501
502		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
503
504		Defines the Monahans turbo mode to oscillator
505		ratio. Valid values are 1 (default if undefined) and
506		2. The core frequency as calculated above is multiplied
507		by this value.
508
509- MIPS CPU options:
510		CONFIG_SYS_INIT_SP_OFFSET
511
512		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
513		pointer. This is needed for the temporary stack before
514		relocation.
515
516		CONFIG_SYS_MIPS_CACHE_MODE
517
518		Cache operation mode for the MIPS CPU.
519		See also arch/mips/include/asm/mipsregs.h.
520		Possible values are:
521			CONF_CM_CACHABLE_NO_WA
522			CONF_CM_CACHABLE_WA
523			CONF_CM_UNCACHED
524			CONF_CM_CACHABLE_NONCOHERENT
525			CONF_CM_CACHABLE_CE
526			CONF_CM_CACHABLE_COW
527			CONF_CM_CACHABLE_CUW
528			CONF_CM_CACHABLE_ACCELERATED
529
530		CONFIG_SYS_XWAY_EBU_BOOTCFG
531
532		Special option for Lantiq XWAY SoCs for booting from NOR flash.
533		See also arch/mips/cpu/mips32/start.S.
534
535		CONFIG_XWAY_SWAP_BYTES
536
537		Enable compilation of tools/xway-swap-bytes needed for Lantiq
538		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
539		be swapped if a flash programmer is used.
540
541- ARM options:
542		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
543
544		Select high exception vectors of the ARM core, e.g., do not
545		clear the V bit of the c1 register of CP15.
546
547		CONFIG_SYS_THUMB_BUILD
548
549		Use this flag to build U-Boot using the Thumb instruction
550		set for ARM architectures. Thumb instruction set provides
551		better code density. For ARM architectures that support
552		Thumb2 this flag will result in Thumb2 code generated by
553		GCC.
554
555		CONFIG_ARM_ERRATA_716044
556		CONFIG_ARM_ERRATA_742230
557		CONFIG_ARM_ERRATA_743622
558		CONFIG_ARM_ERRATA_751472
559
560		If set, the workarounds for these ARM errata are applied early
561		during U-Boot startup. Note that these options force the
562		workarounds to be applied; no CPU-type/version detection
563		exists, unlike the similar options in the Linux kernel. Do not
564		set these options unless they apply!
565
566- CPU timer options:
567		CONFIG_SYS_HZ
568
569		The frequency of the timer returned by get_timer().
570		get_timer() must operate in milliseconds and this CONFIG
571		option must be set to 1000.
572
573- Linux Kernel Interface:
574		CONFIG_CLOCKS_IN_MHZ
575
576		U-Boot stores all clock information in Hz
577		internally. For binary compatibility with older Linux
578		kernels (which expect the clocks passed in the
579		bd_info data to be in MHz) the environment variable
580		"clocks_in_mhz" can be defined so that U-Boot
581		converts clock data to MHZ before passing it to the
582		Linux kernel.
583		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
584		"clocks_in_mhz=1" is automatically included in the
585		default environment.
586
587		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
588
589		When transferring memsize parameter to linux, some versions
590		expect it to be in bytes, others in MB.
591		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
592
593		CONFIG_OF_LIBFDT
594
595		New kernel versions are expecting firmware settings to be
596		passed using flattened device trees (based on open firmware
597		concepts).
598
599		CONFIG_OF_LIBFDT
600		 * New libfdt-based support
601		 * Adds the "fdt" command
602		 * The bootm command automatically updates the fdt
603
604		OF_CPU - The proper name of the cpus node (only required for
605			MPC512X and MPC5xxx based boards).
606		OF_SOC - The proper name of the soc node (only required for
607			MPC512X and MPC5xxx based boards).
608		OF_TBCLK - The timebase frequency.
609		OF_STDOUT_PATH - The path to the console device
610
611		boards with QUICC Engines require OF_QE to set UCC MAC
612		addresses
613
614		CONFIG_OF_BOARD_SETUP
615
616		Board code has addition modification that it wants to make
617		to the flat device tree before handing it off to the kernel
618
619		CONFIG_OF_BOOT_CPU
620
621		This define fills in the correct boot CPU in the boot
622		param header, the default value is zero if undefined.
623
624		CONFIG_OF_IDE_FIXUP
625
626		U-Boot can detect if an IDE device is present or not.
627		If not, and this new config option is activated, U-Boot
628		removes the ATA node from the DTS before booting Linux,
629		so the Linux IDE driver does not probe the device and
630		crash. This is needed for buggy hardware (uc101) where
631		no pull down resistor is connected to the signal IDE5V_DD7.
632
633		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
634
635		This setting is mandatory for all boards that have only one
636		machine type and must be used to specify the machine type
637		number as it appears in the ARM machine registry
638		(see http://www.arm.linux.org.uk/developer/machines/).
639		Only boards that have multiple machine types supported
640		in a single configuration file and the machine type is
641		runtime discoverable, do not have to use this setting.
642
643- vxWorks boot parameters:
644
645		bootvx constructs a valid bootline using the following
646		environments variables: bootfile, ipaddr, serverip, hostname.
647		It loads the vxWorks image pointed bootfile.
648
649		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
650		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
651		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
652		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
653
654		CONFIG_SYS_VXWORKS_ADD_PARAMS
655
656		Add it at the end of the bootline. E.g "u=username pw=secret"
657
658		Note: If a "bootargs" environment is defined, it will overwride
659		the defaults discussed just above.
660
661- Cache Configuration:
662		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
663		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
664		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
665
666- Cache Configuration for ARM:
667		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
668				      controller
669		CONFIG_SYS_PL310_BASE - Physical base address of PL310
670					controller register space
671
672- Serial Ports:
673		CONFIG_PL010_SERIAL
674
675		Define this if you want support for Amba PrimeCell PL010 UARTs.
676
677		CONFIG_PL011_SERIAL
678
679		Define this if you want support for Amba PrimeCell PL011 UARTs.
680
681		CONFIG_PL011_CLOCK
682
683		If you have Amba PrimeCell PL011 UARTs, set this variable to
684		the clock speed of the UARTs.
685
686		CONFIG_PL01x_PORTS
687
688		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
689		define this to a list of base addresses for each (supported)
690		port. See e.g. include/configs/versatile.h
691
692		CONFIG_PL011_SERIAL_RLCR
693
694		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
695		have separate receive and transmit line control registers.  Set
696		this variable to initialize the extra register.
697
698		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
699
700		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
701		boot loader that has already initialized the UART.  Define this
702		variable to flush the UART at init time.
703
704
705- Console Interface:
706		Depending on board, define exactly one serial port
707		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
708		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
709		console by defining CONFIG_8xx_CONS_NONE
710
711		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
712		port routines must be defined elsewhere
713		(i.e. serial_init(), serial_getc(), ...)
714
715		CONFIG_CFB_CONSOLE
716		Enables console device for a color framebuffer. Needs following
717		defines (cf. smiLynxEM, i8042)
718			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
719						(default big endian)
720			VIDEO_HW_RECTFILL	graphic chip supports
721						rectangle fill
722						(cf. smiLynxEM)
723			VIDEO_HW_BITBLT		graphic chip supports
724						bit-blit (cf. smiLynxEM)
725			VIDEO_VISIBLE_COLS	visible pixel columns
726						(cols=pitch)
727			VIDEO_VISIBLE_ROWS	visible pixel rows
728			VIDEO_PIXEL_SIZE	bytes per pixel
729			VIDEO_DATA_FORMAT	graphic data format
730						(0-5, cf. cfb_console.c)
731			VIDEO_FB_ADRS		framebuffer address
732			VIDEO_KBD_INIT_FCT	keyboard int fct
733						(i.e. i8042_kbd_init())
734			VIDEO_TSTC_FCT		test char fct
735						(i.e. i8042_tstc)
736			VIDEO_GETC_FCT		get char fct
737						(i.e. i8042_getc)
738			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
739						(requires blink timer
740						cf. i8042.c)
741			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
742			CONFIG_CONSOLE_TIME	display time/date info in
743						upper right corner
744						(requires CONFIG_CMD_DATE)
745			CONFIG_VIDEO_LOGO	display Linux logo in
746						upper left corner
747			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
748						linux_logo.h for logo.
749						Requires CONFIG_VIDEO_LOGO
750			CONFIG_CONSOLE_EXTRA_INFO
751						additional board info beside
752						the logo
753
754		When CONFIG_CFB_CONSOLE_ANSI is defined, console will support
755		a limited number of ANSI escape sequences (cursor control,
756		erase functions and limited graphics rendition control).
757
758		When CONFIG_CFB_CONSOLE is defined, video console is
759		default i/o. Serial console can be forced with
760		environment 'console=serial'.
761
762		When CONFIG_SILENT_CONSOLE is defined, all console
763		messages (by U-Boot and Linux!) can be silenced with
764		the "silent" environment variable. See
765		doc/README.silent for more information.
766
767		CONFIG_SYS_CONSOLE_BG_COL: define the backgroundcolor, default
768			is 0x00.
769		CONFIG_SYS_CONSOLE_FG_COL: define the foregroundcolor, default
770			is 0xa0.
771
772- Console Baudrate:
773		CONFIG_BAUDRATE - in bps
774		Select one of the baudrates listed in
775		CONFIG_SYS_BAUDRATE_TABLE, see below.
776		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
777
778- Console Rx buffer length
779		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
780		the maximum receive buffer length for the SMC.
781		This option is actual only for 82xx and 8xx possible.
782		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
783		must be defined, to setup the maximum idle timeout for
784		the SMC.
785
786- Pre-Console Buffer:
787		Prior to the console being initialised (i.e. serial UART
788		initialised etc) all console output is silently discarded.
789		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
790		buffer any console messages prior to the console being
791		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
792		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
793		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
794		bytes are output before the console is initialised, the
795		earlier bytes are discarded.
796
797		'Sane' compilers will generate smaller code if
798		CONFIG_PRE_CON_BUF_SZ is a power of 2
799
800- Safe printf() functions
801		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
802		the printf() functions. These are defined in
803		include/vsprintf.h and include snprintf(), vsnprintf() and
804		so on. Code size increase is approximately 300-500 bytes.
805		If this option is not given then these functions will
806		silently discard their buffer size argument - this means
807		you are not getting any overflow checking in this case.
808
809- Boot Delay:	CONFIG_BOOTDELAY - in seconds
810		Delay before automatically booting the default image;
811		set to -1 to disable autoboot.
812		set to -2 to autoboot with no delay and not check for abort
813		(even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).
814
815		See doc/README.autoboot for these options that
816		work with CONFIG_BOOTDELAY. None are required.
817		CONFIG_BOOT_RETRY_TIME
818		CONFIG_BOOT_RETRY_MIN
819		CONFIG_AUTOBOOT_KEYED
820		CONFIG_AUTOBOOT_PROMPT
821		CONFIG_AUTOBOOT_DELAY_STR
822		CONFIG_AUTOBOOT_STOP_STR
823		CONFIG_AUTOBOOT_DELAY_STR2
824		CONFIG_AUTOBOOT_STOP_STR2
825		CONFIG_ZERO_BOOTDELAY_CHECK
826		CONFIG_RESET_TO_RETRY
827
828- Autoboot Command:
829		CONFIG_BOOTCOMMAND
830		Only needed when CONFIG_BOOTDELAY is enabled;
831		define a command string that is automatically executed
832		when no character is read on the console interface
833		within "Boot Delay" after reset.
834
835		CONFIG_BOOTARGS
836		This can be used to pass arguments to the bootm
837		command. The value of CONFIG_BOOTARGS goes into the
838		environment value "bootargs".
839
840		CONFIG_RAMBOOT and CONFIG_NFSBOOT
841		The value of these goes into the environment as
842		"ramboot" and "nfsboot" respectively, and can be used
843		as a convenience, when switching between booting from
844		RAM and NFS.
845
846- Bootcount:
847		CONFIG_BOOTCOUNT_LIMIT
848		Implements a mechanism for detecting a repeating reboot
849		cycle, see:
850		http://www.denx.de/wiki/view/DULG/UBootBootCountLimit
851
852		CONFIG_BOOTCOUNT_ENV
853		If no softreset save registers are found on the hardware
854		"bootcount" is stored in the environment. To prevent a
855		saveenv on all reboots, the environment variable
856		"upgrade_available" is used. If "upgrade_available" is
857		0, "bootcount" is always 0, if "upgrade_available" is
858		1 "bootcount" is incremented in the environment.
859		So the Userspace Applikation must set the "upgrade_available"
860		and "bootcount" variable to 0, if a boot was successfully.
861
862- Pre-Boot Commands:
863		CONFIG_PREBOOT
864
865		When this option is #defined, the existence of the
866		environment variable "preboot" will be checked
867		immediately before starting the CONFIG_BOOTDELAY
868		countdown and/or running the auto-boot command resp.
869		entering interactive mode.
870
871		This feature is especially useful when "preboot" is
872		automatically generated or modified. For an example
873		see the LWMON board specific code: here "preboot" is
874		modified when the user holds down a certain
875		combination of keys on the (special) keyboard when
876		booting the systems
877
878- Serial Download Echo Mode:
879		CONFIG_LOADS_ECHO
880		If defined to 1, all characters received during a
881		serial download (using the "loads" command) are
882		echoed back. This might be needed by some terminal
883		emulations (like "cu"), but may as well just take
884		time on others. This setting #define's the initial
885		value of the "loads_echo" environment variable.
886
887- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
888		CONFIG_KGDB_BAUDRATE
889		Select one of the baudrates listed in
890		CONFIG_SYS_BAUDRATE_TABLE, see below.
891
892- Monitor Functions:
893		Monitor commands can be included or excluded
894		from the build by using the #include files
895		<config_cmd_all.h> and #undef'ing unwanted
896		commands, or using <config_cmd_default.h>
897		and augmenting with additional #define's
898		for wanted commands.
899
900		The default command configuration includes all commands
901		except those marked below with a "*".
902
903		CONFIG_CMD_ASKENV	* ask for env variable
904		CONFIG_CMD_BDI		  bdinfo
905		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
906		CONFIG_CMD_BMP		* BMP support
907		CONFIG_CMD_BSP		* Board specific commands
908		CONFIG_CMD_BOOTD	  bootd
909		CONFIG_CMD_CACHE	* icache, dcache
910		CONFIG_CMD_CLK   	* clock command support
911		CONFIG_CMD_CONSOLE	  coninfo
912		CONFIG_CMD_CRC32	* crc32
913		CONFIG_CMD_DATE		* support for RTC, date/time...
914		CONFIG_CMD_DHCP		* DHCP support
915		CONFIG_CMD_DIAG		* Diagnostics
916		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
917		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
918		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
919		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
920		CONFIG_CMD_DTT		* Digital Therm and Thermostat
921		CONFIG_CMD_ECHO		  echo arguments
922		CONFIG_CMD_EDITENV	  edit env variable
923		CONFIG_CMD_EEPROM	* EEPROM read/write support
924		CONFIG_CMD_ELF		* bootelf, bootvx
925		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
926		CONFIG_CMD_ENV_FLAGS	* display details about env flags
927		CONFIG_CMD_ENV_EXISTS	* check existence of env variable
928		CONFIG_CMD_EXPORTENV	* export the environment
929		CONFIG_CMD_EXT2		* ext2 command support
930		CONFIG_CMD_EXT4		* ext4 command support
931		CONFIG_CMD_FS_GENERIC	* filesystem commands (e.g. load, ls)
932					  that work for multiple fs types
933		CONFIG_CMD_SAVEENV	  saveenv
934		CONFIG_CMD_FDC		* Floppy Disk Support
935		CONFIG_CMD_FAT		* FAT command support
936		CONFIG_CMD_FLASH	  flinfo, erase, protect
937		CONFIG_CMD_FPGA		  FPGA device initialization support
938		CONFIG_CMD_FUSE		* Device fuse support
939		CONFIG_CMD_GETTIME	* Get time since boot
940		CONFIG_CMD_GO		* the 'go' command (exec code)
941		CONFIG_CMD_GREPENV	* search environment
942		CONFIG_CMD_HASH		* calculate hash / digest
943		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
944		CONFIG_CMD_I2C		* I2C serial bus support
945		CONFIG_CMD_IDE		* IDE harddisk support
946		CONFIG_CMD_IMI		  iminfo
947		CONFIG_CMD_IMLS		  List all images found in NOR flash
948		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash
949		CONFIG_CMD_IMMAP	* IMMR dump support
950		CONFIG_CMD_IMPORTENV	* import an environment
951		CONFIG_CMD_INI		* import data from an ini file into the env
952		CONFIG_CMD_IRQ		* irqinfo
953		CONFIG_CMD_ITEST	  Integer/string test of 2 values
954		CONFIG_CMD_JFFS2	* JFFS2 Support
955		CONFIG_CMD_KGDB		* kgdb
956		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)
957		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
958					  (169.254.*.*)
959		CONFIG_CMD_LOADB	  loadb
960		CONFIG_CMD_LOADS	  loads
961		CONFIG_CMD_MD5SUM	* print md5 message digest
962					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
963		CONFIG_CMD_MEMINFO	* Display detailed memory information
964		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
965					  loop, loopw
966		CONFIG_CMD_MEMTEST	* mtest
967		CONFIG_CMD_MISC		  Misc functions like sleep etc
968		CONFIG_CMD_MMC		* MMC memory mapped support
969		CONFIG_CMD_MII		* MII utility commands
970		CONFIG_CMD_MTDPARTS	* MTD partition support
971		CONFIG_CMD_NAND		* NAND support
972		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
973		CONFIG_CMD_NFS		  NFS support
974		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
975		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
976		CONFIG_CMD_PCI		* pciinfo
977		CONFIG_CMD_PCMCIA		* PCMCIA support
978		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
979					  host
980		CONFIG_CMD_PORTIO	* Port I/O
981		CONFIG_CMD_READ		* Read raw data from partition
982		CONFIG_CMD_REGINFO	* Register dump
983		CONFIG_CMD_RUN		  run command in env variable
984		CONFIG_CMD_SANDBOX	* sb command to access sandbox features
985		CONFIG_CMD_SAVES	* save S record dump
986		CONFIG_CMD_SCSI		* SCSI Support
987		CONFIG_CMD_SDRAM	* print SDRAM configuration information
988					  (requires CONFIG_CMD_I2C)
989		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
990					  (4xx only)
991		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
992		CONFIG_CMD_SHA1SUM	* print sha1 memory digest
993					  (requires CONFIG_CMD_MEMORY)
994		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x
995		CONFIG_CMD_SOURCE	  "source" command Support
996		CONFIG_CMD_SPI		* SPI serial bus support
997		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
998		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
999		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
1000		CONFIG_CMD_TIMER	* access to the system tick timer
1001		CONFIG_CMD_USB		* USB support
1002		CONFIG_CMD_CDP		* Cisco Discover Protocol support
1003		CONFIG_CMD_MFSL		* Microblaze FSL support
1004		CONFIG_CMD_XIMG		  Load part of Multi Image
1005
1006
1007		EXAMPLE: If you want all functions except of network
1008		support you can write:
1009
1010		#include "config_cmd_all.h"
1011		#undef CONFIG_CMD_NET
1012
1013	Other Commands:
1014		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
1015
1016	Note:	Don't enable the "icache" and "dcache" commands
1017		(configuration option CONFIG_CMD_CACHE) unless you know
1018		what you (and your U-Boot users) are doing. Data
1019		cache cannot be enabled on systems like the 8xx or
1020		8260 (where accesses to the IMMR region must be
1021		uncached), and it cannot be disabled on all other
1022		systems where we (mis-) use the data cache to hold an
1023		initial stack and some data.
1024
1025
1026		XXX - this list needs to get updated!
1027
1028- Regular expression support:
1029		CONFIG_REGEX
1030		If this variable is defined, U-Boot is linked against
1031		the SLRE (Super Light Regular Expression) library,
1032		which adds regex support to some commands, as for
1033		example "env grep" and "setexpr".
1034
1035- Device tree:
1036		CONFIG_OF_CONTROL
1037		If this variable is defined, U-Boot will use a device tree
1038		to configure its devices, instead of relying on statically
1039		compiled #defines in the board file. This option is
1040		experimental and only available on a few boards. The device
1041		tree is available in the global data as gd->fdt_blob.
1042
1043		U-Boot needs to get its device tree from somewhere. This can
1044		be done using one of the two options below:
1045
1046		CONFIG_OF_EMBED
1047		If this variable is defined, U-Boot will embed a device tree
1048		binary in its image. This device tree file should be in the
1049		board directory and called <soc>-<board>.dts. The binary file
1050		is then picked up in board_init_f() and made available through
1051		the global data structure as gd->blob.
1052
1053		CONFIG_OF_SEPARATE
1054		If this variable is defined, U-Boot will build a device tree
1055		binary. It will be called u-boot.dtb. Architecture-specific
1056		code will locate it at run-time. Generally this works by:
1057
1058			cat u-boot.bin u-boot.dtb >image.bin
1059
1060		and in fact, U-Boot does this for you, creating a file called
1061		u-boot-dtb.bin which is useful in the common case. You can
1062		still use the individual files if you need something more
1063		exotic.
1064
1065- Watchdog:
1066		CONFIG_WATCHDOG
1067		If this variable is defined, it enables watchdog
1068		support for the SoC. There must be support in the SoC
1069		specific code for a watchdog. For the 8xx and 8260
1070		CPUs, the SIU Watchdog feature is enabled in the SYPCR
1071		register.  When supported for a specific SoC is
1072		available, then no further board specific code should
1073		be needed to use it.
1074
1075		CONFIG_HW_WATCHDOG
1076		When using a watchdog circuitry external to the used
1077		SoC, then define this variable and provide board
1078		specific code for the "hw_watchdog_reset" function.
1079
1080- U-Boot Version:
1081		CONFIG_VERSION_VARIABLE
1082		If this variable is defined, an environment variable
1083		named "ver" is created by U-Boot showing the U-Boot
1084		version as printed by the "version" command.
1085		Any change to this variable will be reverted at the
1086		next reset.
1087
1088- Real-Time Clock:
1089
1090		When CONFIG_CMD_DATE is selected, the type of the RTC
1091		has to be selected, too. Define exactly one of the
1092		following options:
1093
1094		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
1095		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
1096		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
1097		CONFIG_RTC_MC146818	- use MC146818 RTC
1098		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
1099		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
1100		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
1101		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
1102		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
1103		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
1104		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
1105		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
1106					  RV3029 RTC.
1107
1108		Note that if the RTC uses I2C, then the I2C interface
1109		must also be configured. See I2C Support, below.
1110
1111- GPIO Support:
1112		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
1113
1114		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1115		chip-ngpio pairs that tell the PCA953X driver the number of
1116		pins supported by a particular chip.
1117
1118		Note that if the GPIO device uses I2C, then the I2C interface
1119		must also be configured. See I2C Support, below.
1120
1121- Timestamp Support:
1122
1123		When CONFIG_TIMESTAMP is selected, the timestamp
1124		(date and time) of an image is printed by image
1125		commands like bootm or iminfo. This option is
1126		automatically enabled when you select CONFIG_CMD_DATE .
1127
1128- Partition Labels (disklabels) Supported:
1129		Zero or more of the following:
1130		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1131		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1132				       Intel architecture, USB sticks, etc.
1133		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1134		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1135				       bootloader.  Note 2TB partition limit; see
1136				       disk/part_efi.c
1137		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1138
1139		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1140		CONFIG_CMD_SCSI) you must configure support for at
1141		least one non-MTD partition type as well.
1142
1143- IDE Reset method:
1144		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1145		board configurations files but used nowhere!
1146
1147		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1148		be performed by calling the function
1149			ide_set_reset(int reset)
1150		which has to be defined in a board specific file
1151
1152- ATAPI Support:
1153		CONFIG_ATAPI
1154
1155		Set this to enable ATAPI support.
1156
1157- LBA48 Support
1158		CONFIG_LBA48
1159
1160		Set this to enable support for disks larger than 137GB
1161		Also look at CONFIG_SYS_64BIT_LBA.
1162		Whithout these , LBA48 support uses 32bit variables and will 'only'
1163		support disks up to 2.1TB.
1164
1165		CONFIG_SYS_64BIT_LBA:
1166			When enabled, makes the IDE subsystem use 64bit sector addresses.
1167			Default is 32bit.
1168
1169- SCSI Support:
1170		At the moment only there is only support for the
1171		SYM53C8XX SCSI controller; define
1172		CONFIG_SCSI_SYM53C8XX to enable it.
1173
1174		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1175		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1176		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1177		maximum numbers of LUNs, SCSI ID's and target
1178		devices.
1179		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1180
1181		The environment variable 'scsidevs' is set to the number of
1182		SCSI devices found during the last scan.
1183
1184- NETWORK Support (PCI):
1185		CONFIG_E1000
1186		Support for Intel 8254x/8257x gigabit chips.
1187
1188		CONFIG_E1000_SPI
1189		Utility code for direct access to the SPI bus on Intel 8257x.
1190		This does not do anything useful unless you set at least one
1191		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1192
1193		CONFIG_E1000_SPI_GENERIC
1194		Allow generic access to the SPI bus on the Intel 8257x, for
1195		example with the "sspi" command.
1196
1197		CONFIG_CMD_E1000
1198		Management command for E1000 devices.  When used on devices
1199		with SPI support you can reprogram the EEPROM from U-Boot.
1200
1201		CONFIG_E1000_FALLBACK_MAC
1202		default MAC for empty EEPROM after production.
1203
1204		CONFIG_EEPRO100
1205		Support for Intel 82557/82559/82559ER chips.
1206		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1207		write routine for first time initialisation.
1208
1209		CONFIG_TULIP
1210		Support for Digital 2114x chips.
1211		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1212		modem chip initialisation (KS8761/QS6611).
1213
1214		CONFIG_NATSEMI
1215		Support for National dp83815 chips.
1216
1217		CONFIG_NS8382X
1218		Support for National dp8382[01] gigabit chips.
1219
1220- NETWORK Support (other):
1221
1222		CONFIG_DRIVER_AT91EMAC
1223		Support for AT91RM9200 EMAC.
1224
1225			CONFIG_RMII
1226			Define this to use reduced MII inteface
1227
1228			CONFIG_DRIVER_AT91EMAC_QUIET
1229			If this defined, the driver is quiet.
1230			The driver doen't show link status messages.
1231
1232		CONFIG_CALXEDA_XGMAC
1233		Support for the Calxeda XGMAC device
1234
1235		CONFIG_LAN91C96
1236		Support for SMSC's LAN91C96 chips.
1237
1238			CONFIG_LAN91C96_BASE
1239			Define this to hold the physical address
1240			of the LAN91C96's I/O space
1241
1242			CONFIG_LAN91C96_USE_32_BIT
1243			Define this to enable 32 bit addressing
1244
1245		CONFIG_SMC91111
1246		Support for SMSC's LAN91C111 chip
1247
1248			CONFIG_SMC91111_BASE
1249			Define this to hold the physical address
1250			of the device (I/O space)
1251
1252			CONFIG_SMC_USE_32_BIT
1253			Define this if data bus is 32 bits
1254
1255			CONFIG_SMC_USE_IOFUNCS
1256			Define this to use i/o functions instead of macros
1257			(some hardware wont work with macros)
1258
1259		CONFIG_DRIVER_TI_EMAC
1260		Support for davinci emac
1261
1262			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1263			Define this if you have more then 3 PHYs.
1264
1265		CONFIG_FTGMAC100
1266		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1267
1268			CONFIG_FTGMAC100_EGIGA
1269			Define this to use GE link update with gigabit PHY.
1270			Define this if FTGMAC100 is connected to gigabit PHY.
1271			If your system has 10/100 PHY only, it might not occur
1272			wrong behavior. Because PHY usually return timeout or
1273			useless data when polling gigabit status and gigabit
1274			control registers. This behavior won't affect the
1275			correctnessof 10/100 link speed update.
1276
1277		CONFIG_SMC911X
1278		Support for SMSC's LAN911x and LAN921x chips
1279
1280			CONFIG_SMC911X_BASE
1281			Define this to hold the physical address
1282			of the device (I/O space)
1283
1284			CONFIG_SMC911X_32_BIT
1285			Define this if data bus is 32 bits
1286
1287			CONFIG_SMC911X_16_BIT
1288			Define this if data bus is 16 bits. If your processor
1289			automatically converts one 32 bit word to two 16 bit
1290			words you may also try CONFIG_SMC911X_32_BIT.
1291
1292		CONFIG_SH_ETHER
1293		Support for Renesas on-chip Ethernet controller
1294
1295			CONFIG_SH_ETHER_USE_PORT
1296			Define the number of ports to be used
1297
1298			CONFIG_SH_ETHER_PHY_ADDR
1299			Define the ETH PHY's address
1300
1301			CONFIG_SH_ETHER_CACHE_WRITEBACK
1302			If this option is set, the driver enables cache flush.
1303
1304- TPM Support:
1305		CONFIG_TPM
1306		Support TPM devices.
1307
1308		CONFIG_TPM_TIS_I2C
1309		Support for i2c bus TPM devices. Only one device
1310		per system is supported at this time.
1311
1312			CONFIG_TPM_TIS_I2C_BUS_NUMBER
1313			Define the the i2c bus number for the TPM device
1314
1315			CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS
1316			Define the TPM's address on the i2c bus
1317
1318			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1319			Define the burst count bytes upper limit
1320
1321		CONFIG_TPM_ATMEL_TWI
1322		Support for Atmel TWI TPM device. Requires I2C support.
1323
1324		CONFIG_TPM_TIS_LPC
1325		Support for generic parallel port TPM devices. Only one device
1326		per system is supported at this time.
1327
1328			CONFIG_TPM_TIS_BASE_ADDRESS
1329			Base address where the generic TPM device is mapped
1330			to. Contemporary x86 systems usually map it at
1331			0xfed40000.
1332
1333		CONFIG_CMD_TPM
1334		Add tpm monitor functions.
1335		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1336		provides monitor access to authorized functions.
1337
1338		CONFIG_TPM
1339		Define this to enable the TPM support library which provides
1340		functional interfaces to some TPM commands.
1341		Requires support for a TPM device.
1342
1343		CONFIG_TPM_AUTH_SESSIONS
1344		Define this to enable authorized functions in the TPM library.
1345		Requires CONFIG_TPM and CONFIG_SHA1.
1346
1347- USB Support:
1348		At the moment only the UHCI host controller is
1349		supported (PIP405, MIP405, MPC5200); define
1350		CONFIG_USB_UHCI to enable it.
1351		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1352		and define CONFIG_USB_STORAGE to enable the USB
1353		storage devices.
1354		Note:
1355		Supported are USB Keyboards and USB Floppy drives
1356		(TEAC FD-05PUB).
1357		MPC5200 USB requires additional defines:
1358			CONFIG_USB_CLOCK
1359				for 528 MHz Clock: 0x0001bbbb
1360			CONFIG_PSC3_USB
1361				for USB on PSC3
1362			CONFIG_USB_CONFIG
1363				for differential drivers: 0x00001000
1364				for single ended drivers: 0x00005000
1365				for differential drivers on PSC3: 0x00000100
1366				for single ended drivers on PSC3: 0x00004100
1367			CONFIG_SYS_USB_EVENT_POLL
1368				May be defined to allow interrupt polling
1369				instead of using asynchronous interrupts
1370
1371		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1372		txfilltuning field in the EHCI controller on reset.
1373
1374		CONFIG_USB_HUB_MIN_POWER_ON_DELAY defines the minimum
1375		interval for usb hub power-on delay.(minimum 100msec)
1376
1377- USB Device:
1378		Define the below if you wish to use the USB console.
1379		Once firmware is rebuilt from a serial console issue the
1380		command "setenv stdin usbtty; setenv stdout usbtty" and
1381		attach your USB cable. The Unix command "dmesg" should print
1382		it has found a new device. The environment variable usbtty
1383		can be set to gserial or cdc_acm to enable your device to
1384		appear to a USB host as a Linux gserial device or a
1385		Common Device Class Abstract Control Model serial device.
1386		If you select usbtty = gserial you should be able to enumerate
1387		a Linux host by
1388		# modprobe usbserial vendor=0xVendorID product=0xProductID
1389		else if using cdc_acm, simply setting the environment
1390		variable usbtty to be cdc_acm should suffice. The following
1391		might be defined in YourBoardName.h
1392
1393			CONFIG_USB_DEVICE
1394			Define this to build a UDC device
1395
1396			CONFIG_USB_TTY
1397			Define this to have a tty type of device available to
1398			talk to the UDC device
1399
1400			CONFIG_USBD_HS
1401			Define this to enable the high speed support for usb
1402			device and usbtty. If this feature is enabled, a routine
1403			int is_usbd_high_speed(void)
1404			also needs to be defined by the driver to dynamically poll
1405			whether the enumeration has succeded at high speed or full
1406			speed.
1407
1408			CONFIG_SYS_CONSOLE_IS_IN_ENV
1409			Define this if you want stdin, stdout &/or stderr to
1410			be set to usbtty.
1411
1412			mpc8xx:
1413				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1414				Derive USB clock from external clock "blah"
1415				- CONFIG_SYS_USB_EXTC_CLK 0x02
1416
1417				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1418				Derive USB clock from brgclk
1419				- CONFIG_SYS_USB_BRG_CLK 0x04
1420
1421		If you have a USB-IF assigned VendorID then you may wish to
1422		define your own vendor specific values either in BoardName.h
1423		or directly in usbd_vendor_info.h. If you don't define
1424		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1425		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1426		should pretend to be a Linux device to it's target host.
1427
1428			CONFIG_USBD_MANUFACTURER
1429			Define this string as the name of your company for
1430			- CONFIG_USBD_MANUFACTURER "my company"
1431
1432			CONFIG_USBD_PRODUCT_NAME
1433			Define this string as the name of your product
1434			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1435
1436			CONFIG_USBD_VENDORID
1437			Define this as your assigned Vendor ID from the USB
1438			Implementors Forum. This *must* be a genuine Vendor ID
1439			to avoid polluting the USB namespace.
1440			- CONFIG_USBD_VENDORID 0xFFFF
1441
1442			CONFIG_USBD_PRODUCTID
1443			Define this as the unique Product ID
1444			for your device
1445			- CONFIG_USBD_PRODUCTID 0xFFFF
1446
1447		Some USB device drivers may need to check USB cable attachment.
1448		In this case you can enable following config in BoardName.h:
1449			CONFIG_USB_CABLE_CHECK
1450			This enables function definition:
1451			- usb_cable_connected() in include/usb.h
1452			Implementation of this function is board-specific.
1453
1454- ULPI Layer Support:
1455		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1456		the generic ULPI layer. The generic layer accesses the ULPI PHY
1457		via the platform viewport, so you need both the genric layer and
1458		the viewport enabled. Currently only Chipidea/ARC based
1459		viewport is supported.
1460		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1461		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1462		If your ULPI phy needs a different reference clock than the
1463		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1464		the appropriate value in Hz.
1465
1466- MMC Support:
1467		The MMC controller on the Intel PXA is supported. To
1468		enable this define CONFIG_MMC. The MMC can be
1469		accessed from the boot prompt by mapping the device
1470		to physical memory similar to flash. Command line is
1471		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1472		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1473
1474		CONFIG_SH_MMCIF
1475		Support for Renesas on-chip MMCIF controller
1476
1477			CONFIG_SH_MMCIF_ADDR
1478			Define the base address of MMCIF registers
1479
1480			CONFIG_SH_MMCIF_CLK
1481			Define the clock frequency for MMCIF
1482
1483- USB Device Firmware Update (DFU) class support:
1484		CONFIG_DFU_FUNCTION
1485		This enables the USB portion of the DFU USB class
1486
1487		CONFIG_CMD_DFU
1488		This enables the command "dfu" which is used to have
1489		U-Boot create a DFU class device via USB.  This command
1490		requires that the "dfu_alt_info" environment variable be
1491		set and define the alt settings to expose to the host.
1492
1493		CONFIG_DFU_MMC
1494		This enables support for exposing (e)MMC devices via DFU.
1495
1496		CONFIG_DFU_NAND
1497		This enables support for exposing NAND devices via DFU.
1498
1499		CONFIG_DFU_RAM
1500		This enables support for exposing RAM via DFU.
1501		Note: DFU spec refer to non-volatile memory usage, but
1502		allow usages beyond the scope of spec - here RAM usage,
1503		one that would help mostly the developer.
1504
1505		CONFIG_SYS_DFU_DATA_BUF_SIZE
1506		Dfu transfer uses a buffer before writing data to the
1507		raw storage device. Make the size (in bytes) of this buffer
1508		configurable. The size of this buffer is also configurable
1509		through the "dfu_bufsiz" environment variable.
1510
1511		CONFIG_SYS_DFU_MAX_FILE_SIZE
1512		When updating files rather than the raw storage device,
1513		we use a static buffer to copy the file into and then write
1514		the buffer once we've been given the whole file.  Define
1515		this to the maximum filesize (in bytes) for the buffer.
1516		Default is 4 MiB if undefined.
1517
1518- Journaling Flash filesystem support:
1519		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1520		CONFIG_JFFS2_NAND_DEV
1521		Define these for a default partition on a NAND device
1522
1523		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1524		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1525		Define these for a default partition on a NOR device
1526
1527		CONFIG_SYS_JFFS_CUSTOM_PART
1528		Define this to create an own partition. You have to provide a
1529		function struct part_info* jffs2_part_info(int part_num)
1530
1531		If you define only one JFFS2 partition you may also want to
1532		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1533		to disable the command chpart. This is the default when you
1534		have not defined a custom partition
1535
1536- FAT(File Allocation Table) filesystem write function support:
1537		CONFIG_FAT_WRITE
1538
1539		Define this to enable support for saving memory data as a
1540		file in FAT formatted partition.
1541
1542		This will also enable the command "fatwrite" enabling the
1543		user to write files to FAT.
1544
1545CBFS (Coreboot Filesystem) support
1546		CONFIG_CMD_CBFS
1547
1548		Define this to enable support for reading from a Coreboot
1549		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1550		and cbfsload.
1551
1552- Keyboard Support:
1553		CONFIG_ISA_KEYBOARD
1554
1555		Define this to enable standard (PC-Style) keyboard
1556		support
1557
1558		CONFIG_I8042_KBD
1559		Standard PC keyboard driver with US (is default) and
1560		GERMAN key layout (switch via environment 'keymap=de') support.
1561		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1562		for cfb_console. Supports cursor blinking.
1563
1564		CONFIG_CROS_EC_KEYB
1565		Enables a Chrome OS keyboard using the CROS_EC interface.
1566		This uses CROS_EC to communicate with a second microcontroller
1567		which provides key scans on request.
1568
1569- Video support:
1570		CONFIG_VIDEO
1571
1572		Define this to enable video support (for output to
1573		video).
1574
1575		CONFIG_VIDEO_CT69000
1576
1577		Enable Chips & Technologies 69000 Video chip
1578
1579		CONFIG_VIDEO_SMI_LYNXEM
1580		Enable Silicon Motion SMI 712/710/810 Video chip. The
1581		video output is selected via environment 'videoout'
1582		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1583		assumed.
1584
1585		For the CT69000 and SMI_LYNXEM drivers, videomode is
1586		selected via environment 'videomode'. Two different ways
1587		are possible:
1588		- "videomode=num"   'num' is a standard LiLo mode numbers.
1589		Following standard modes are supported	(* is default):
1590
1591		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1592		-------------+---------------------------------------------
1593		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1594		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1595		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1596		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1597		-------------+---------------------------------------------
1598		(i.e. setenv videomode 317; saveenv; reset;)
1599
1600		- "videomode=bootargs" all the video parameters are parsed
1601		from the bootargs. (See drivers/video/videomodes.c)
1602
1603
1604		CONFIG_VIDEO_SED13806
1605		Enable Epson SED13806 driver. This driver supports 8bpp
1606		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1607		or CONFIG_VIDEO_SED13806_16BPP
1608
1609		CONFIG_FSL_DIU_FB
1610		Enable the Freescale DIU video driver.	Reference boards for
1611		SOCs that have a DIU should define this macro to enable DIU
1612		support, and should also define these other macros:
1613
1614			CONFIG_SYS_DIU_ADDR
1615			CONFIG_VIDEO
1616			CONFIG_CMD_BMP
1617			CONFIG_CFB_CONSOLE
1618			CONFIG_VIDEO_SW_CURSOR
1619			CONFIG_VGA_AS_SINGLE_DEVICE
1620			CONFIG_VIDEO_LOGO
1621			CONFIG_VIDEO_BMP_LOGO
1622
1623		The DIU driver will look for the 'video-mode' environment
1624		variable, and if defined, enable the DIU as a console during
1625		boot.  See the documentation file README.video for a
1626		description of this variable.
1627
1628		CONFIG_VIDEO_VGA
1629
1630		Enable the VGA video / BIOS for x86. The alternative if you
1631		are using coreboot is to use the coreboot frame buffer
1632		driver.
1633
1634
1635- Keyboard Support:
1636		CONFIG_KEYBOARD
1637
1638		Define this to enable a custom keyboard support.
1639		This simply calls drv_keyboard_init() which must be
1640		defined in your board-specific files.
1641		The only board using this so far is RBC823.
1642
1643- LCD Support:	CONFIG_LCD
1644
1645		Define this to enable LCD support (for output to LCD
1646		display); also select one of the supported displays
1647		by defining one of these:
1648
1649		CONFIG_ATMEL_LCD:
1650
1651			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1652
1653		CONFIG_NEC_NL6448AC33:
1654
1655			NEC NL6448AC33-18. Active, color, single scan.
1656
1657		CONFIG_NEC_NL6448BC20
1658
1659			NEC NL6448BC20-08. 6.5", 640x480.
1660			Active, color, single scan.
1661
1662		CONFIG_NEC_NL6448BC33_54
1663
1664			NEC NL6448BC33-54. 10.4", 640x480.
1665			Active, color, single scan.
1666
1667		CONFIG_SHARP_16x9
1668
1669			Sharp 320x240. Active, color, single scan.
1670			It isn't 16x9, and I am not sure what it is.
1671
1672		CONFIG_SHARP_LQ64D341
1673
1674			Sharp LQ64D341 display, 640x480.
1675			Active, color, single scan.
1676
1677		CONFIG_HLD1045
1678
1679			HLD1045 display, 640x480.
1680			Active, color, single scan.
1681
1682		CONFIG_OPTREX_BW
1683
1684			Optrex	 CBL50840-2 NF-FW 99 22 M5
1685			or
1686			Hitachi	 LMG6912RPFC-00T
1687			or
1688			Hitachi	 SP14Q002
1689
1690			320x240. Black & white.
1691
1692		Normally display is black on white background; define
1693		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1694
1695		CONFIG_LCD_ALIGNMENT
1696
1697		Normally the LCD is page-aligned (tyically 4KB). If this is
1698		defined then the LCD will be aligned to this value instead.
1699		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1700		here, since it is cheaper to change data cache settings on
1701		a per-section basis.
1702
1703		CONFIG_CONSOLE_SCROLL_LINES
1704
1705		When the console need to be scrolled, this is the number of
1706		lines to scroll by. It defaults to 1. Increasing this makes
1707		the console jump but can help speed up operation when scrolling
1708		is slow.
1709
1710		CONFIG_LCD_BMP_RLE8
1711
1712		Support drawing of RLE8-compressed bitmaps on the LCD.
1713
1714		CONFIG_I2C_EDID
1715
1716		Enables an 'i2c edid' command which can read EDID
1717		information over I2C from an attached LCD display.
1718
1719- Splash Screen Support: CONFIG_SPLASH_SCREEN
1720
1721		If this option is set, the environment is checked for
1722		a variable "splashimage". If found, the usual display
1723		of logo, copyright and system information on the LCD
1724		is suppressed and the BMP image at the address
1725		specified in "splashimage" is loaded instead. The
1726		console is redirected to the "nulldev", too. This
1727		allows for a "silent" boot where a splash screen is
1728		loaded very quickly after power-on.
1729
1730		CONFIG_SPLASHIMAGE_GUARD
1731
1732		If this option is set, then U-Boot will prevent the environment
1733		variable "splashimage" from being set to a problematic address
1734		(see README.displaying-bmps and README.arm-unaligned-accesses).
1735		This option is useful for targets where, due to alignment
1736		restrictions, an improperly aligned BMP image will cause a data
1737		abort. If you think you will not have problems with unaligned
1738		accesses (for example because your toolchain prevents them)
1739		there is no need to set this option.
1740
1741		CONFIG_SPLASH_SCREEN_ALIGN
1742
1743		If this option is set the splash image can be freely positioned
1744		on the screen. Environment variable "splashpos" specifies the
1745		position as "x,y". If a positive number is given it is used as
1746		number of pixel from left/top. If a negative number is given it
1747		is used as number of pixel from right/bottom. You can also
1748		specify 'm' for centering the image.
1749
1750		Example:
1751		setenv splashpos m,m
1752			=> image at center of screen
1753
1754		setenv splashpos 30,20
1755			=> image at x = 30 and y = 20
1756
1757		setenv splashpos -10,m
1758			=> vertically centered image
1759			   at x = dspWidth - bmpWidth - 9
1760
1761- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1762
1763		If this option is set, additionally to standard BMP
1764		images, gzipped BMP images can be displayed via the
1765		splashscreen support or the bmp command.
1766
1767- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1768
1769		If this option is set, 8-bit RLE compressed BMP images
1770		can be displayed via the splashscreen support or the
1771		bmp command.
1772
1773- Do compresssing for memory range:
1774		CONFIG_CMD_ZIP
1775
1776		If this option is set, it would use zlib deflate method
1777		to compress the specified memory at its best effort.
1778
1779- Compression support:
1780		CONFIG_GZIP
1781
1782		Enabled by default to support gzip compressed images.
1783
1784		CONFIG_BZIP2
1785
1786		If this option is set, support for bzip2 compressed
1787		images is included. If not, only uncompressed and gzip
1788		compressed images are supported.
1789
1790		NOTE: the bzip2 algorithm requires a lot of RAM, so
1791		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1792		be at least 4MB.
1793
1794		CONFIG_LZMA
1795
1796		If this option is set, support for lzma compressed
1797		images is included.
1798
1799		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1800		requires an amount of dynamic memory that is given by the
1801		formula:
1802
1803			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1804
1805		Where lc and lp stand for, respectively, Literal context bits
1806		and Literal pos bits.
1807
1808		This value is upper-bounded by 14MB in the worst case. Anyway,
1809		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1810		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1811		a very small buffer.
1812
1813		Use the lzmainfo tool to determinate the lc and lp values and
1814		then calculate the amount of needed dynamic memory (ensuring
1815		the appropriate CONFIG_SYS_MALLOC_LEN value).
1816
1817		CONFIG_LZO
1818
1819		If this option is set, support for LZO compressed images
1820		is included.
1821
1822- MII/PHY support:
1823		CONFIG_PHY_ADDR
1824
1825		The address of PHY on MII bus.
1826
1827		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1828
1829		The clock frequency of the MII bus
1830
1831		CONFIG_PHY_GIGE
1832
1833		If this option is set, support for speed/duplex
1834		detection of gigabit PHY is included.
1835
1836		CONFIG_PHY_RESET_DELAY
1837
1838		Some PHY like Intel LXT971A need extra delay after
1839		reset before any MII register access is possible.
1840		For such PHY, set this option to the usec delay
1841		required. (minimum 300usec for LXT971A)
1842
1843		CONFIG_PHY_CMD_DELAY (ppc4xx)
1844
1845		Some PHY like Intel LXT971A need extra delay after
1846		command issued before MII status register can be read
1847
1848- Ethernet address:
1849		CONFIG_ETHADDR
1850		CONFIG_ETH1ADDR
1851		CONFIG_ETH2ADDR
1852		CONFIG_ETH3ADDR
1853		CONFIG_ETH4ADDR
1854		CONFIG_ETH5ADDR
1855
1856		Define a default value for Ethernet address to use
1857		for the respective Ethernet interface, in case this
1858		is not determined automatically.
1859
1860- IP address:
1861		CONFIG_IPADDR
1862
1863		Define a default value for the IP address to use for
1864		the default Ethernet interface, in case this is not
1865		determined through e.g. bootp.
1866		(Environment variable "ipaddr")
1867
1868- Server IP address:
1869		CONFIG_SERVERIP
1870
1871		Defines a default value for the IP address of a TFTP
1872		server to contact when using the "tftboot" command.
1873		(Environment variable "serverip")
1874
1875		CONFIG_KEEP_SERVERADDR
1876
1877		Keeps the server's MAC address, in the env 'serveraddr'
1878		for passing to bootargs (like Linux's netconsole option)
1879
1880- Gateway IP address:
1881		CONFIG_GATEWAYIP
1882
1883		Defines a default value for the IP address of the
1884		default router where packets to other networks are
1885		sent to.
1886		(Environment variable "gatewayip")
1887
1888- Subnet mask:
1889		CONFIG_NETMASK
1890
1891		Defines a default value for the subnet mask (or
1892		routing prefix) which is used to determine if an IP
1893		address belongs to the local subnet or needs to be
1894		forwarded through a router.
1895		(Environment variable "netmask")
1896
1897- Multicast TFTP Mode:
1898		CONFIG_MCAST_TFTP
1899
1900		Defines whether you want to support multicast TFTP as per
1901		rfc-2090; for example to work with atftp.  Lets lots of targets
1902		tftp down the same boot image concurrently.  Note: the Ethernet
1903		driver in use must provide a function: mcast() to join/leave a
1904		multicast group.
1905
1906- BOOTP Recovery Mode:
1907		CONFIG_BOOTP_RANDOM_DELAY
1908
1909		If you have many targets in a network that try to
1910		boot using BOOTP, you may want to avoid that all
1911		systems send out BOOTP requests at precisely the same
1912		moment (which would happen for instance at recovery
1913		from a power failure, when all systems will try to
1914		boot, thus flooding the BOOTP server. Defining
1915		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1916		inserted before sending out BOOTP requests. The
1917		following delays are inserted then:
1918
1919		1st BOOTP request:	delay 0 ... 1 sec
1920		2nd BOOTP request:	delay 0 ... 2 sec
1921		3rd BOOTP request:	delay 0 ... 4 sec
1922		4th and following
1923		BOOTP requests:		delay 0 ... 8 sec
1924
1925- DHCP Advanced Options:
1926		You can fine tune the DHCP functionality by defining
1927		CONFIG_BOOTP_* symbols:
1928
1929		CONFIG_BOOTP_SUBNETMASK
1930		CONFIG_BOOTP_GATEWAY
1931		CONFIG_BOOTP_HOSTNAME
1932		CONFIG_BOOTP_NISDOMAIN
1933		CONFIG_BOOTP_BOOTPATH
1934		CONFIG_BOOTP_BOOTFILESIZE
1935		CONFIG_BOOTP_DNS
1936		CONFIG_BOOTP_DNS2
1937		CONFIG_BOOTP_SEND_HOSTNAME
1938		CONFIG_BOOTP_NTPSERVER
1939		CONFIG_BOOTP_TIMEOFFSET
1940		CONFIG_BOOTP_VENDOREX
1941		CONFIG_BOOTP_MAY_FAIL
1942
1943		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1944		environment variable, not the BOOTP server.
1945
1946		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1947		after the configured retry count, the call will fail
1948		instead of starting over.  This can be used to fail over
1949		to Link-local IP address configuration if the DHCP server
1950		is not available.
1951
1952		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1953		serverip from a DHCP server, it is possible that more
1954		than one DNS serverip is offered to the client.
1955		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1956		serverip will be stored in the additional environment
1957		variable "dnsip2". The first DNS serverip is always
1958		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1959		is defined.
1960
1961		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1962		to do a dynamic update of a DNS server. To do this, they
1963		need the hostname of the DHCP requester.
1964		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1965		of the "hostname" environment variable is passed as
1966		option 12 to the DHCP server.
1967
1968		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1969
1970		A 32bit value in microseconds for a delay between
1971		receiving a "DHCP Offer" and sending the "DHCP Request".
1972		This fixes a problem with certain DHCP servers that don't
1973		respond 100% of the time to a "DHCP request". E.g. On an
1974		AT91RM9200 processor running at 180MHz, this delay needed
1975		to be *at least* 15,000 usec before a Windows Server 2003
1976		DHCP server would reply 100% of the time. I recommend at
1977		least 50,000 usec to be safe. The alternative is to hope
1978		that one of the retries will be successful but note that
1979		the DHCP timeout and retry process takes a longer than
1980		this delay.
1981
1982 - Link-local IP address negotiation:
1983		Negotiate with other link-local clients on the local network
1984		for an address that doesn't require explicit configuration.
1985		This is especially useful if a DHCP server cannot be guaranteed
1986		to exist in all environments that the device must operate.
1987
1988		See doc/README.link-local for more information.
1989
1990 - CDP Options:
1991		CONFIG_CDP_DEVICE_ID
1992
1993		The device id used in CDP trigger frames.
1994
1995		CONFIG_CDP_DEVICE_ID_PREFIX
1996
1997		A two character string which is prefixed to the MAC address
1998		of the device.
1999
2000		CONFIG_CDP_PORT_ID
2001
2002		A printf format string which contains the ascii name of
2003		the port. Normally is set to "eth%d" which sets
2004		eth0 for the first Ethernet, eth1 for the second etc.
2005
2006		CONFIG_CDP_CAPABILITIES
2007
2008		A 32bit integer which indicates the device capabilities;
2009		0x00000010 for a normal host which does not forwards.
2010
2011		CONFIG_CDP_VERSION
2012
2013		An ascii string containing the version of the software.
2014
2015		CONFIG_CDP_PLATFORM
2016
2017		An ascii string containing the name of the platform.
2018
2019		CONFIG_CDP_TRIGGER
2020
2021		A 32bit integer sent on the trigger.
2022
2023		CONFIG_CDP_POWER_CONSUMPTION
2024
2025		A 16bit integer containing the power consumption of the
2026		device in .1 of milliwatts.
2027
2028		CONFIG_CDP_APPLIANCE_VLAN_TYPE
2029
2030		A byte containing the id of the VLAN.
2031
2032- Status LED:	CONFIG_STATUS_LED
2033
2034		Several configurations allow to display the current
2035		status using a LED. For instance, the LED will blink
2036		fast while running U-Boot code, stop blinking as
2037		soon as a reply to a BOOTP request was received, and
2038		start blinking slow once the Linux kernel is running
2039		(supported by a status LED driver in the Linux
2040		kernel). Defining CONFIG_STATUS_LED enables this
2041		feature in U-Boot.
2042
2043		Additional options:
2044
2045		CONFIG_GPIO_LED
2046		The status LED can be connected to a GPIO pin.
2047		In such cases, the gpio_led driver can be used as a
2048		status LED backend implementation. Define CONFIG_GPIO_LED
2049		to include the gpio_led driver in the U-Boot binary.
2050
2051		CONFIG_GPIO_LED_INVERTED_TABLE
2052		Some GPIO connected LEDs may have inverted polarity in which
2053		case the GPIO high value corresponds to LED off state and
2054		GPIO low value corresponds to LED on state.
2055		In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
2056		with a list of GPIO LEDs that have inverted polarity.
2057
2058- CAN Support:	CONFIG_CAN_DRIVER
2059
2060		Defining CONFIG_CAN_DRIVER enables CAN driver support
2061		on those systems that support this (optional)
2062		feature, like the TQM8xxL modules.
2063
2064- I2C Support:	CONFIG_SYS_I2C
2065
2066		This enable the NEW i2c subsystem, and will allow you to use
2067		i2c commands at the u-boot command line (as long as you set
2068		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
2069		based realtime clock chips or other i2c devices. See
2070		common/cmd_i2c.c for a description of the command line
2071		interface.
2072
2073		ported i2c driver to the new framework:
2074		- drivers/i2c/soft_i2c.c:
2075		  - activate first bus with CONFIG_SYS_I2C_SOFT define
2076		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
2077		    for defining speed and slave address
2078		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
2079		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
2080		    for defining speed and slave address
2081		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
2082		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
2083		    for defining speed and slave address
2084		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
2085		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
2086		    for defining speed and slave address
2087
2088		- drivers/i2c/fsl_i2c.c:
2089		  - activate i2c driver with CONFIG_SYS_I2C_FSL
2090		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
2091		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
2092		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
2093		    bus.
2094		  - If your board supports a second fsl i2c bus, define
2095		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
2096		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
2097		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
2098		    second bus.
2099
2100		- drivers/i2c/tegra_i2c.c:
2101		  - activate this driver with CONFIG_SYS_I2C_TEGRA
2102		  - This driver adds 4 i2c buses with a fix speed from
2103		    100000 and the slave addr 0!
2104
2105		- drivers/i2c/ppc4xx_i2c.c
2106		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
2107		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
2108		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
2109
2110		- drivers/i2c/i2c_mxc.c
2111		  - activate this driver with CONFIG_SYS_I2C_MXC
2112		  - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
2113		  - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
2114		  - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
2115		  - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
2116		  - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
2117		  - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
2118		If thoses defines are not set, default value is 100000
2119		for speed, and 0 for slave.
2120
2121		- drivers/i2c/rcar_i2c.c:
2122		  - activate this driver with CONFIG_SYS_I2C_RCAR
2123		  - This driver adds 4 i2c buses
2124
2125		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
2126		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
2127		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
2128		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
2129		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
2130		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
2131		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
2132		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
2133		  - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
2134
2135		- drivers/i2c/sh_i2c.c:
2136		  - activate this driver with CONFIG_SYS_I2C_SH
2137		  - This driver adds from 2 to 5 i2c buses
2138
2139		  - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
2140		  - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
2141		  - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
2142		  - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
2143		  - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
2144		  - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
2145		  - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
2146		  - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
2147		  - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
2148		  - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
2149		  - CONFIG_SYS_I2C_SH_BASE5 for setting the register channel 5
2150		  - CONFIG_SYS_I2C_SH_SPEED5 for for the speed channel 5
2151		  - CONFIF_SYS_I2C_SH_NUM_CONTROLLERS for nummber of i2c buses
2152
2153		- drivers/i2c/omap24xx_i2c.c
2154		  - activate this driver with CONFIG_SYS_I2C_OMAP24XX
2155		  - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
2156		  - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
2157		  - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
2158		  - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
2159		  - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
2160		  - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
2161		  - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
2162		  - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
2163		  - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
2164		  - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
2165
2166		- drivers/i2c/zynq_i2c.c
2167		  - activate this driver with CONFIG_SYS_I2C_ZYNQ
2168		  - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
2169		  - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
2170
2171		- drivers/i2c/s3c24x0_i2c.c:
2172		  - activate this driver with CONFIG_SYS_I2C_S3C24X0
2173		  - This driver adds i2c buses (11 for Exynos5250, Exynos5420
2174		    9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
2175		    with a fix speed from 100000 and the slave addr 0!
2176
2177		additional defines:
2178
2179		CONFIG_SYS_NUM_I2C_BUSES
2180		Hold the number of i2c busses you want to use. If you
2181		don't use/have i2c muxes on your i2c bus, this
2182		is equal to CONFIG_SYS_NUM_I2C_ADAPTERS, and you can
2183		omit this define.
2184
2185		CONFIG_SYS_I2C_DIRECT_BUS
2186		define this, if you don't use i2c muxes on your hardware.
2187		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2188		omit this define.
2189
2190		CONFIG_SYS_I2C_MAX_HOPS
2191		define how many muxes are maximal consecutively connected
2192		on one i2c bus. If you not use i2c muxes, omit this
2193		define.
2194
2195		CONFIG_SYS_I2C_BUSES
2196		hold a list of busses you want to use, only used if
2197		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2198		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2199		CONFIG_SYS_NUM_I2C_BUSES = 9:
2200
2201		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
2202					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2203					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2204					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2205					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2206					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2207					{1, {I2C_NULL_HOP}}, \
2208					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2209					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2210					}
2211
2212		which defines
2213			bus 0 on adapter 0 without a mux
2214			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2215			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2216			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2217			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2218			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2219			bus 6 on adapter 1 without a mux
2220			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2221			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2222
2223		If you do not have i2c muxes on your board, omit this define.
2224
2225- Legacy I2C Support:	CONFIG_HARD_I2C
2226
2227		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2228		provides the following compelling advantages:
2229
2230		- more than one i2c adapter is usable
2231		- approved multibus support
2232		- better i2c mux support
2233
2234		** Please consider updating your I2C driver now. **
2235
2236		These enable legacy I2C serial bus commands. Defining
2237		CONFIG_HARD_I2C will include the appropriate I2C driver
2238		for the selected CPU.
2239
2240		This will allow you to use i2c commands at the u-boot
2241		command line (as long as you set CONFIG_CMD_I2C in
2242		CONFIG_COMMANDS) and communicate with i2c based realtime
2243		clock chips. See common/cmd_i2c.c for a description of the
2244		command line interface.
2245
2246		CONFIG_HARD_I2C selects a hardware I2C controller.
2247
2248		There are several other quantities that must also be
2249		defined when you define CONFIG_HARD_I2C.
2250
2251		In both cases you will need to define CONFIG_SYS_I2C_SPEED
2252		to be the frequency (in Hz) at which you wish your i2c bus
2253		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2254		the CPU's i2c node address).
2255
2256		Now, the u-boot i2c code for the mpc8xx
2257		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2258		and so its address should therefore be cleared to 0 (See,
2259		eg, MPC823e User's Manual p.16-473). So, set
2260		CONFIG_SYS_I2C_SLAVE to 0.
2261
2262		CONFIG_SYS_I2C_INIT_MPC5XXX
2263
2264		When a board is reset during an i2c bus transfer
2265		chips might think that the current transfer is still
2266		in progress.  Reset the slave devices by sending start
2267		commands until the slave device responds.
2268
2269		That's all that's required for CONFIG_HARD_I2C.
2270
2271		If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2272		then the following macros need to be defined (examples are
2273		from include/configs/lwmon.h):
2274
2275		I2C_INIT
2276
2277		(Optional). Any commands necessary to enable the I2C
2278		controller or configure ports.
2279
2280		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2281
2282		I2C_PORT
2283
2284		(Only for MPC8260 CPU). The I/O port to use (the code
2285		assumes both bits are on the same port). Valid values
2286		are 0..3 for ports A..D.
2287
2288		I2C_ACTIVE
2289
2290		The code necessary to make the I2C data line active
2291		(driven).  If the data line is open collector, this
2292		define can be null.
2293
2294		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2295
2296		I2C_TRISTATE
2297
2298		The code necessary to make the I2C data line tri-stated
2299		(inactive).  If the data line is open collector, this
2300		define can be null.
2301
2302		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2303
2304		I2C_READ
2305
2306		Code that returns true if the I2C data line is high,
2307		false if it is low.
2308
2309		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2310
2311		I2C_SDA(bit)
2312
2313		If <bit> is true, sets the I2C data line high. If it
2314		is false, it clears it (low).
2315
2316		eg: #define I2C_SDA(bit) \
2317			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2318			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2319
2320		I2C_SCL(bit)
2321
2322		If <bit> is true, sets the I2C clock line high. If it
2323		is false, it clears it (low).
2324
2325		eg: #define I2C_SCL(bit) \
2326			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2327			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2328
2329		I2C_DELAY
2330
2331		This delay is invoked four times per clock cycle so this
2332		controls the rate of data transfer.  The data rate thus
2333		is 1 / (I2C_DELAY * 4). Often defined to be something
2334		like:
2335
2336		#define I2C_DELAY  udelay(2)
2337
2338		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2339
2340		If your arch supports the generic GPIO framework (asm/gpio.h),
2341		then you may alternatively define the two GPIOs that are to be
2342		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2343		have GPIO-based defaults assigned to them as appropriate.
2344
2345		You should define these to the GPIO value as given directly to
2346		the generic GPIO functions.
2347
2348		CONFIG_SYS_I2C_INIT_BOARD
2349
2350		When a board is reset during an i2c bus transfer
2351		chips might think that the current transfer is still
2352		in progress. On some boards it is possible to access
2353		the i2c SCLK line directly, either by using the
2354		processor pin as a GPIO or by having a second pin
2355		connected to the bus. If this option is defined a
2356		custom i2c_init_board() routine in boards/xxx/board.c
2357		is run early in the boot sequence.
2358
2359		CONFIG_SYS_I2C_BOARD_LATE_INIT
2360
2361		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2362		defined a custom i2c_board_late_init() routine in
2363		boards/xxx/board.c is run AFTER the operations in i2c_init()
2364		is completed. This callpoint can be used to unreset i2c bus
2365		using CPU i2c controller register accesses for CPUs whose i2c
2366		controller provide such a method. It is called at the end of
2367		i2c_init() to allow i2c_init operations to setup the i2c bus
2368		controller on the CPU (e.g. setting bus speed & slave address).
2369
2370		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2371
2372		This option enables configuration of bi_iic_fast[] flags
2373		in u-boot bd_info structure based on u-boot environment
2374		variable "i2cfast". (see also i2cfast)
2375
2376		CONFIG_I2C_MULTI_BUS
2377
2378		This option allows the use of multiple I2C buses, each of which
2379		must have a controller.	 At any point in time, only one bus is
2380		active.	 To switch to a different bus, use the 'i2c dev' command.
2381		Note that bus numbering is zero-based.
2382
2383		CONFIG_SYS_I2C_NOPROBES
2384
2385		This option specifies a list of I2C devices that will be skipped
2386		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2387		is set, specify a list of bus-device pairs.  Otherwise, specify
2388		a 1D array of device addresses
2389
2390		e.g.
2391			#undef	CONFIG_I2C_MULTI_BUS
2392			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2393
2394		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2395
2396			#define CONFIG_I2C_MULTI_BUS
2397			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2398
2399		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2400
2401		CONFIG_SYS_SPD_BUS_NUM
2402
2403		If defined, then this indicates the I2C bus number for DDR SPD.
2404		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2405
2406		CONFIG_SYS_RTC_BUS_NUM
2407
2408		If defined, then this indicates the I2C bus number for the RTC.
2409		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2410
2411		CONFIG_SYS_DTT_BUS_NUM
2412
2413		If defined, then this indicates the I2C bus number for the DTT.
2414		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2415
2416		CONFIG_SYS_I2C_DTT_ADDR:
2417
2418		If defined, specifies the I2C address of the DTT device.
2419		If not defined, then U-Boot uses predefined value for
2420		specified DTT device.
2421
2422		CONFIG_SOFT_I2C_READ_REPEATED_START
2423
2424		defining this will force the i2c_read() function in
2425		the soft_i2c driver to perform an I2C repeated start
2426		between writing the address pointer and reading the
2427		data.  If this define is omitted the default behaviour
2428		of doing a stop-start sequence will be used.  Most I2C
2429		devices can use either method, but some require one or
2430		the other.
2431
2432- SPI Support:	CONFIG_SPI
2433
2434		Enables SPI driver (so far only tested with
2435		SPI EEPROM, also an instance works with Crystal A/D and
2436		D/As on the SACSng board)
2437
2438		CONFIG_SH_SPI
2439
2440		Enables the driver for SPI controller on SuperH. Currently
2441		only SH7757 is supported.
2442
2443		CONFIG_SPI_X
2444
2445		Enables extended (16-bit) SPI EEPROM addressing.
2446		(symmetrical to CONFIG_I2C_X)
2447
2448		CONFIG_SOFT_SPI
2449
2450		Enables a software (bit-bang) SPI driver rather than
2451		using hardware support. This is a general purpose
2452		driver that only requires three general I/O port pins
2453		(two outputs, one input) to function. If this is
2454		defined, the board configuration must define several
2455		SPI configuration items (port pins to use, etc). For
2456		an example, see include/configs/sacsng.h.
2457
2458		CONFIG_HARD_SPI
2459
2460		Enables a hardware SPI driver for general-purpose reads
2461		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2462		must define a list of chip-select function pointers.
2463		Currently supported on some MPC8xxx processors.	 For an
2464		example, see include/configs/mpc8349emds.h.
2465
2466		CONFIG_MXC_SPI
2467
2468		Enables the driver for the SPI controllers on i.MX and MXC
2469		SoCs. Currently i.MX31/35/51 are supported.
2470
2471- FPGA Support: CONFIG_FPGA
2472
2473		Enables FPGA subsystem.
2474
2475		CONFIG_FPGA_<vendor>
2476
2477		Enables support for specific chip vendors.
2478		(ALTERA, XILINX)
2479
2480		CONFIG_FPGA_<family>
2481
2482		Enables support for FPGA family.
2483		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2484
2485		CONFIG_FPGA_COUNT
2486
2487		Specify the number of FPGA devices to support.
2488
2489		CONFIG_SYS_FPGA_PROG_FEEDBACK
2490
2491		Enable printing of hash marks during FPGA configuration.
2492
2493		CONFIG_SYS_FPGA_CHECK_BUSY
2494
2495		Enable checks on FPGA configuration interface busy
2496		status by the configuration function. This option
2497		will require a board or device specific function to
2498		be written.
2499
2500		CONFIG_FPGA_DELAY
2501
2502		If defined, a function that provides delays in the FPGA
2503		configuration driver.
2504
2505		CONFIG_SYS_FPGA_CHECK_CTRLC
2506		Allow Control-C to interrupt FPGA configuration
2507
2508		CONFIG_SYS_FPGA_CHECK_ERROR
2509
2510		Check for configuration errors during FPGA bitfile
2511		loading. For example, abort during Virtex II
2512		configuration if the INIT_B line goes low (which
2513		indicated a CRC error).
2514
2515		CONFIG_SYS_FPGA_WAIT_INIT
2516
2517		Maximum time to wait for the INIT_B line to deassert
2518		after PROB_B has been deasserted during a Virtex II
2519		FPGA configuration sequence. The default time is 500
2520		ms.
2521
2522		CONFIG_SYS_FPGA_WAIT_BUSY
2523
2524		Maximum time to wait for BUSY to deassert during
2525		Virtex II FPGA configuration. The default is 5 ms.
2526
2527		CONFIG_SYS_FPGA_WAIT_CONFIG
2528
2529		Time to wait after FPGA configuration. The default is
2530		200 ms.
2531
2532- Configuration Management:
2533		CONFIG_IDENT_STRING
2534
2535		If defined, this string will be added to the U-Boot
2536		version information (U_BOOT_VERSION)
2537
2538- Vendor Parameter Protection:
2539
2540		U-Boot considers the values of the environment
2541		variables "serial#" (Board Serial Number) and
2542		"ethaddr" (Ethernet Address) to be parameters that
2543		are set once by the board vendor / manufacturer, and
2544		protects these variables from casual modification by
2545		the user. Once set, these variables are read-only,
2546		and write or delete attempts are rejected. You can
2547		change this behaviour:
2548
2549		If CONFIG_ENV_OVERWRITE is #defined in your config
2550		file, the write protection for vendor parameters is
2551		completely disabled. Anybody can change or delete
2552		these parameters.
2553
2554		Alternatively, if you #define _both_ CONFIG_ETHADDR
2555		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2556		Ethernet address is installed in the environment,
2557		which can be changed exactly ONCE by the user. [The
2558		serial# is unaffected by this, i. e. it remains
2559		read-only.]
2560
2561		The same can be accomplished in a more flexible way
2562		for any variable by configuring the type of access
2563		to allow for those variables in the ".flags" variable
2564		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2565
2566- Protected RAM:
2567		CONFIG_PRAM
2568
2569		Define this variable to enable the reservation of
2570		"protected RAM", i. e. RAM which is not overwritten
2571		by U-Boot. Define CONFIG_PRAM to hold the number of
2572		kB you want to reserve for pRAM. You can overwrite
2573		this default value by defining an environment
2574		variable "pram" to the number of kB you want to
2575		reserve. Note that the board info structure will
2576		still show the full amount of RAM. If pRAM is
2577		reserved, a new environment variable "mem" will
2578		automatically be defined to hold the amount of
2579		remaining RAM in a form that can be passed as boot
2580		argument to Linux, for instance like that:
2581
2582			setenv bootargs ... mem=\${mem}
2583			saveenv
2584
2585		This way you can tell Linux not to use this memory,
2586		either, which results in a memory region that will
2587		not be affected by reboots.
2588
2589		*WARNING* If your board configuration uses automatic
2590		detection of the RAM size, you must make sure that
2591		this memory test is non-destructive. So far, the
2592		following board configurations are known to be
2593		"pRAM-clean":
2594
2595			IVMS8, IVML24, SPD8xx, TQM8xxL,
2596			HERMES, IP860, RPXlite, LWMON,
2597			FLAGADM, TQM8260
2598
2599- Access to physical memory region (> 4GB)
2600		Some basic support is provided for operations on memory not
2601		normally accessible to U-Boot - e.g. some architectures
2602		support access to more than 4GB of memory on 32-bit
2603		machines using physical address extension or similar.
2604		Define CONFIG_PHYSMEM to access this basic support, which
2605		currently only supports clearing the memory.
2606
2607- Error Recovery:
2608		CONFIG_PANIC_HANG
2609
2610		Define this variable to stop the system in case of a
2611		fatal error, so that you have to reset it manually.
2612		This is probably NOT a good idea for an embedded
2613		system where you want the system to reboot
2614		automatically as fast as possible, but it may be
2615		useful during development since you can try to debug
2616		the conditions that lead to the situation.
2617
2618		CONFIG_NET_RETRY_COUNT
2619
2620		This variable defines the number of retries for
2621		network operations like ARP, RARP, TFTP, or BOOTP
2622		before giving up the operation. If not defined, a
2623		default value of 5 is used.
2624
2625		CONFIG_ARP_TIMEOUT
2626
2627		Timeout waiting for an ARP reply in milliseconds.
2628
2629		CONFIG_NFS_TIMEOUT
2630
2631		Timeout in milliseconds used in NFS protocol.
2632		If you encounter "ERROR: Cannot umount" in nfs command,
2633		try longer timeout such as
2634		#define CONFIG_NFS_TIMEOUT 10000UL
2635
2636- Command Interpreter:
2637		CONFIG_AUTO_COMPLETE
2638
2639		Enable auto completion of commands using TAB.
2640
2641		Note that this feature has NOT been implemented yet
2642		for the "hush" shell.
2643
2644
2645		CONFIG_SYS_HUSH_PARSER
2646
2647		Define this variable to enable the "hush" shell (from
2648		Busybox) as command line interpreter, thus enabling
2649		powerful command line syntax like
2650		if...then...else...fi conditionals or `&&' and '||'
2651		constructs ("shell scripts").
2652
2653		If undefined, you get the old, much simpler behaviour
2654		with a somewhat smaller memory footprint.
2655
2656
2657		CONFIG_SYS_PROMPT_HUSH_PS2
2658
2659		This defines the secondary prompt string, which is
2660		printed when the command interpreter needs more input
2661		to complete a command. Usually "> ".
2662
2663	Note:
2664
2665		In the current implementation, the local variables
2666		space and global environment variables space are
2667		separated. Local variables are those you define by
2668		simply typing `name=value'. To access a local
2669		variable later on, you have write `$name' or
2670		`${name}'; to execute the contents of a variable
2671		directly type `$name' at the command prompt.
2672
2673		Global environment variables are those you use
2674		setenv/printenv to work with. To run a command stored
2675		in such a variable, you need to use the run command,
2676		and you must not use the '$' sign to access them.
2677
2678		To store commands and special characters in a
2679		variable, please use double quotation marks
2680		surrounding the whole text of the variable, instead
2681		of the backslashes before semicolons and special
2682		symbols.
2683
2684- Commandline Editing and History:
2685		CONFIG_CMDLINE_EDITING
2686
2687		Enable editing and History functions for interactive
2688		commandline input operations
2689
2690- Default Environment:
2691		CONFIG_EXTRA_ENV_SETTINGS
2692
2693		Define this to contain any number of null terminated
2694		strings (variable = value pairs) that will be part of
2695		the default environment compiled into the boot image.
2696
2697		For example, place something like this in your
2698		board's config file:
2699
2700		#define CONFIG_EXTRA_ENV_SETTINGS \
2701			"myvar1=value1\0" \
2702			"myvar2=value2\0"
2703
2704		Warning: This method is based on knowledge about the
2705		internal format how the environment is stored by the
2706		U-Boot code. This is NOT an official, exported
2707		interface! Although it is unlikely that this format
2708		will change soon, there is no guarantee either.
2709		You better know what you are doing here.
2710
2711		Note: overly (ab)use of the default environment is
2712		discouraged. Make sure to check other ways to preset
2713		the environment like the "source" command or the
2714		boot command first.
2715
2716		CONFIG_ENV_VARS_UBOOT_CONFIG
2717
2718		Define this in order to add variables describing the
2719		U-Boot build configuration to the default environment.
2720		These will be named arch, cpu, board, vendor, and soc.
2721
2722		Enabling this option will cause the following to be defined:
2723
2724		- CONFIG_SYS_ARCH
2725		- CONFIG_SYS_CPU
2726		- CONFIG_SYS_BOARD
2727		- CONFIG_SYS_VENDOR
2728		- CONFIG_SYS_SOC
2729
2730		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2731
2732		Define this in order to add variables describing certain
2733		run-time determined information about the hardware to the
2734		environment.  These will be named board_name, board_rev.
2735
2736		CONFIG_DELAY_ENVIRONMENT
2737
2738		Normally the environment is loaded when the board is
2739		intialised so that it is available to U-Boot. This inhibits
2740		that so that the environment is not available until
2741		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2742		this is instead controlled by the value of
2743		/config/load-environment.
2744
2745- DataFlash Support:
2746		CONFIG_HAS_DATAFLASH
2747
2748		Defining this option enables DataFlash features and
2749		allows to read/write in Dataflash via the standard
2750		commands cp, md...
2751
2752- Serial Flash support
2753		CONFIG_CMD_SF
2754
2755		Defining this option enables SPI flash commands
2756		'sf probe/read/write/erase/update'.
2757
2758		Usage requires an initial 'probe' to define the serial
2759		flash parameters, followed by read/write/erase/update
2760		commands.
2761
2762		The following defaults may be provided by the platform
2763		to handle the common case when only a single serial
2764		flash is present on the system.
2765
2766		CONFIG_SF_DEFAULT_BUS		Bus identifier
2767		CONFIG_SF_DEFAULT_CS		Chip-select
2768		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2769		CONFIG_SF_DEFAULT_SPEED		in Hz
2770
2771		CONFIG_CMD_SF_TEST
2772
2773		Define this option to include a destructive SPI flash
2774		test ('sf test').
2775
2776		CONFIG_SPI_FLASH_BAR		Ban/Extended Addr Reg
2777
2778		Define this option to use the Bank addr/Extended addr
2779		support on SPI flashes which has size > 16Mbytes.
2780
2781		CONFIG_SF_DUAL_FLASH		Dual flash memories
2782
2783		Define this option to use dual flash support where two flash
2784		memories can be connected with a given cs line.
2785		currently Xilinx Zynq qspi support these type of connections.
2786
2787- SystemACE Support:
2788		CONFIG_SYSTEMACE
2789
2790		Adding this option adds support for Xilinx SystemACE
2791		chips attached via some sort of local bus. The address
2792		of the chip must also be defined in the
2793		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2794
2795		#define CONFIG_SYSTEMACE
2796		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2797
2798		When SystemACE support is added, the "ace" device type
2799		becomes available to the fat commands, i.e. fatls.
2800
2801- TFTP Fixed UDP Port:
2802		CONFIG_TFTP_PORT
2803
2804		If this is defined, the environment variable tftpsrcp
2805		is used to supply the TFTP UDP source port value.
2806		If tftpsrcp isn't defined, the normal pseudo-random port
2807		number generator is used.
2808
2809		Also, the environment variable tftpdstp is used to supply
2810		the TFTP UDP destination port value.  If tftpdstp isn't
2811		defined, the normal port 69 is used.
2812
2813		The purpose for tftpsrcp is to allow a TFTP server to
2814		blindly start the TFTP transfer using the pre-configured
2815		target IP address and UDP port. This has the effect of
2816		"punching through" the (Windows XP) firewall, allowing
2817		the remainder of the TFTP transfer to proceed normally.
2818		A better solution is to properly configure the firewall,
2819		but sometimes that is not allowed.
2820
2821- Hashing support:
2822		CONFIG_CMD_HASH
2823
2824		This enables a generic 'hash' command which can produce
2825		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
2826
2827		CONFIG_HASH_VERIFY
2828
2829		Enable the hash verify command (hash -v). This adds to code
2830		size a little.
2831
2832		CONFIG_SHA1 - support SHA1 hashing
2833		CONFIG_SHA256 - support SHA256 hashing
2834
2835		Note: There is also a sha1sum command, which should perhaps
2836		be deprecated in favour of 'hash sha1'.
2837
2838- Freescale i.MX specific commands:
2839		CONFIG_CMD_HDMIDETECT
2840		This enables 'hdmidet' command which returns true if an
2841		HDMI monitor is detected.  This command is i.MX 6 specific.
2842
2843		CONFIG_CMD_BMODE
2844		This enables the 'bmode' (bootmode) command for forcing
2845		a boot from specific media.
2846
2847		This is useful for forcing the ROM's usb downloader to
2848		activate upon a watchdog reset which is nice when iterating
2849		on U-Boot.  Using the reset button or running bmode normal
2850		will set it back to normal.  This command currently
2851		supports i.MX53 and i.MX6.
2852
2853- Signing support:
2854		CONFIG_RSA
2855
2856		This enables the RSA algorithm used for FIT image verification
2857		in U-Boot. See doc/uImage.FIT/signature.txt for more information.
2858
2859		The signing part is build into mkimage regardless of this
2860		option.
2861
2862- bootcount support:
2863		CONFIG_BOOTCOUNT_LIMIT
2864
2865		This enables the bootcounter support, see:
2866		http://www.denx.de/wiki/DULG/UBootBootCountLimit
2867
2868		CONFIG_AT91SAM9XE
2869		enable special bootcounter support on at91sam9xe based boards.
2870		CONFIG_BLACKFIN
2871		enable special bootcounter support on blackfin based boards.
2872		CONFIG_SOC_DA8XX
2873		enable special bootcounter support on da850 based boards.
2874		CONFIG_BOOTCOUNT_RAM
2875		enable support for the bootcounter in RAM
2876		CONFIG_BOOTCOUNT_I2C
2877		enable support for the bootcounter on an i2c (like RTC) device.
2878			CONFIG_SYS_I2C_RTC_ADDR = i2c chip address
2879			CONFIG_SYS_BOOTCOUNT_ADDR = i2c addr which is used for
2880						    the bootcounter.
2881			CONFIG_BOOTCOUNT_ALEN = address len
2882
2883- Show boot progress:
2884		CONFIG_SHOW_BOOT_PROGRESS
2885
2886		Defining this option allows to add some board-
2887		specific code (calling a user-provided function
2888		"show_boot_progress(int)") that enables you to show
2889		the system's boot progress on some display (for
2890		example, some LED's) on your board. At the moment,
2891		the following checkpoints are implemented:
2892
2893- Detailed boot stage timing
2894		CONFIG_BOOTSTAGE
2895		Define this option to get detailed timing of each stage
2896		of the boot process.
2897
2898		CONFIG_BOOTSTAGE_USER_COUNT
2899		This is the number of available user bootstage records.
2900		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
2901		a new ID will be allocated from this stash. If you exceed
2902		the limit, recording will stop.
2903
2904		CONFIG_BOOTSTAGE_REPORT
2905		Define this to print a report before boot, similar to this:
2906
2907		Timer summary in microseconds:
2908		       Mark    Elapsed  Stage
2909			  0          0  reset
2910		  3,575,678  3,575,678  board_init_f start
2911		  3,575,695         17  arch_cpu_init A9
2912		  3,575,777         82  arch_cpu_init done
2913		  3,659,598     83,821  board_init_r start
2914		  3,910,375    250,777  main_loop
2915		 29,916,167 26,005,792  bootm_start
2916		 30,361,327    445,160  start_kernel
2917
2918		CONFIG_CMD_BOOTSTAGE
2919		Add a 'bootstage' command which supports printing a report
2920		and un/stashing of bootstage data.
2921
2922		CONFIG_BOOTSTAGE_FDT
2923		Stash the bootstage information in the FDT. A root 'bootstage'
2924		node is created with each bootstage id as a child. Each child
2925		has a 'name' property and either 'mark' containing the
2926		mark time in microsecond, or 'accum' containing the
2927		accumulated time for that bootstage id in microseconds.
2928		For example:
2929
2930		bootstage {
2931			154 {
2932				name = "board_init_f";
2933				mark = <3575678>;
2934			};
2935			170 {
2936				name = "lcd";
2937				accum = <33482>;
2938			};
2939		};
2940
2941		Code in the Linux kernel can find this in /proc/devicetree.
2942
2943Legacy uImage format:
2944
2945  Arg	Where			When
2946    1	common/cmd_bootm.c	before attempting to boot an image
2947   -1	common/cmd_bootm.c	Image header has bad	 magic number
2948    2	common/cmd_bootm.c	Image header has correct magic number
2949   -2	common/cmd_bootm.c	Image header has bad	 checksum
2950    3	common/cmd_bootm.c	Image header has correct checksum
2951   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2952    4	common/cmd_bootm.c	Image data   has correct checksum
2953   -4	common/cmd_bootm.c	Image is for unsupported architecture
2954    5	common/cmd_bootm.c	Architecture check OK
2955   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2956    6	common/cmd_bootm.c	Image Type check OK
2957   -6	common/cmd_bootm.c	gunzip uncompression error
2958   -7	common/cmd_bootm.c	Unimplemented compression type
2959    7	common/cmd_bootm.c	Uncompression OK
2960    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2961   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2962
2963    9	common/image.c		Start initial ramdisk verification
2964  -10	common/image.c		Ramdisk header has bad	   magic number
2965  -11	common/image.c		Ramdisk header has bad	   checksum
2966   10	common/image.c		Ramdisk header is OK
2967  -12	common/image.c		Ramdisk data   has bad	   checksum
2968   11	common/image.c		Ramdisk data   has correct checksum
2969   12	common/image.c		Ramdisk verification complete, start loading
2970  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2971   13	common/image.c		Start multifile image verification
2972   14	common/image.c		No initial ramdisk, no multifile, continue.
2973
2974   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2975
2976  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2977  -31	post/post.c		POST test failed, detected by post_output_backlog()
2978  -32	post/post.c		POST test failed, detected by post_run_single()
2979
2980   34	common/cmd_doc.c	before loading a Image from a DOC device
2981  -35	common/cmd_doc.c	Bad usage of "doc" command
2982   35	common/cmd_doc.c	correct usage of "doc" command
2983  -36	common/cmd_doc.c	No boot device
2984   36	common/cmd_doc.c	correct boot device
2985  -37	common/cmd_doc.c	Unknown Chip ID on boot device
2986   37	common/cmd_doc.c	correct chip ID found, device available
2987  -38	common/cmd_doc.c	Read Error on boot device
2988   38	common/cmd_doc.c	reading Image header from DOC device OK
2989  -39	common/cmd_doc.c	Image header has bad magic number
2990   39	common/cmd_doc.c	Image header has correct magic number
2991  -40	common/cmd_doc.c	Error reading Image from DOC device
2992   40	common/cmd_doc.c	Image header has correct magic number
2993   41	common/cmd_ide.c	before loading a Image from a IDE device
2994  -42	common/cmd_ide.c	Bad usage of "ide" command
2995   42	common/cmd_ide.c	correct usage of "ide" command
2996  -43	common/cmd_ide.c	No boot device
2997   43	common/cmd_ide.c	boot device found
2998  -44	common/cmd_ide.c	Device not available
2999   44	common/cmd_ide.c	Device available
3000  -45	common/cmd_ide.c	wrong partition selected
3001   45	common/cmd_ide.c	partition selected
3002  -46	common/cmd_ide.c	Unknown partition table
3003   46	common/cmd_ide.c	valid partition table found
3004  -47	common/cmd_ide.c	Invalid partition type
3005   47	common/cmd_ide.c	correct partition type
3006  -48	common/cmd_ide.c	Error reading Image Header on boot device
3007   48	common/cmd_ide.c	reading Image Header from IDE device OK
3008  -49	common/cmd_ide.c	Image header has bad magic number
3009   49	common/cmd_ide.c	Image header has correct magic number
3010  -50	common/cmd_ide.c	Image header has bad	 checksum
3011   50	common/cmd_ide.c	Image header has correct checksum
3012  -51	common/cmd_ide.c	Error reading Image from IDE device
3013   51	common/cmd_ide.c	reading Image from IDE device OK
3014   52	common/cmd_nand.c	before loading a Image from a NAND device
3015  -53	common/cmd_nand.c	Bad usage of "nand" command
3016   53	common/cmd_nand.c	correct usage of "nand" command
3017  -54	common/cmd_nand.c	No boot device
3018   54	common/cmd_nand.c	boot device found
3019  -55	common/cmd_nand.c	Unknown Chip ID on boot device
3020   55	common/cmd_nand.c	correct chip ID found, device available
3021  -56	common/cmd_nand.c	Error reading Image Header on boot device
3022   56	common/cmd_nand.c	reading Image Header from NAND device OK
3023  -57	common/cmd_nand.c	Image header has bad magic number
3024   57	common/cmd_nand.c	Image header has correct magic number
3025  -58	common/cmd_nand.c	Error reading Image from NAND device
3026   58	common/cmd_nand.c	reading Image from NAND device OK
3027
3028  -60	common/env_common.c	Environment has a bad CRC, using default
3029
3030   64	net/eth.c		starting with Ethernet configuration.
3031  -64	net/eth.c		no Ethernet found.
3032   65	net/eth.c		Ethernet found.
3033
3034  -80	common/cmd_net.c	usage wrong
3035   80	common/cmd_net.c	before calling NetLoop()
3036  -81	common/cmd_net.c	some error in NetLoop() occurred
3037   81	common/cmd_net.c	NetLoop() back without error
3038  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
3039   82	common/cmd_net.c	trying automatic boot
3040   83	common/cmd_net.c	running "source" command
3041  -83	common/cmd_net.c	some error in automatic boot or "source" command
3042   84	common/cmd_net.c	end without errors
3043
3044FIT uImage format:
3045
3046  Arg	Where			When
3047  100	common/cmd_bootm.c	Kernel FIT Image has correct format
3048 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
3049  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
3050 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
3051  102	common/cmd_bootm.c	Kernel unit name specified
3052 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
3053  103	common/cmd_bootm.c	Found configuration node
3054  104	common/cmd_bootm.c	Got kernel subimage node offset
3055 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
3056  105	common/cmd_bootm.c	Kernel subimage hash verification OK
3057 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
3058  106	common/cmd_bootm.c	Architecture check OK
3059 -106	common/cmd_bootm.c	Kernel subimage has wrong type
3060  107	common/cmd_bootm.c	Kernel subimage type OK
3061 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
3062  108	common/cmd_bootm.c	Got kernel subimage data/size
3063 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
3064 -109	common/cmd_bootm.c	Can't get kernel subimage type
3065 -110	common/cmd_bootm.c	Can't get kernel subimage comp
3066 -111	common/cmd_bootm.c	Can't get kernel subimage os
3067 -112	common/cmd_bootm.c	Can't get kernel subimage load address
3068 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
3069
3070  120	common/image.c		Start initial ramdisk verification
3071 -120	common/image.c		Ramdisk FIT image has incorrect format
3072  121	common/image.c		Ramdisk FIT image has correct format
3073  122	common/image.c		No ramdisk subimage unit name, using configuration
3074 -122	common/image.c		Can't get configuration for ramdisk subimage
3075  123	common/image.c		Ramdisk unit name specified
3076 -124	common/image.c		Can't get ramdisk subimage node offset
3077  125	common/image.c		Got ramdisk subimage node offset
3078 -125	common/image.c		Ramdisk subimage hash verification failed
3079  126	common/image.c		Ramdisk subimage hash verification OK
3080 -126	common/image.c		Ramdisk subimage for unsupported architecture
3081  127	common/image.c		Architecture check OK
3082 -127	common/image.c		Can't get ramdisk subimage data/size
3083  128	common/image.c		Got ramdisk subimage data/size
3084  129	common/image.c		Can't get ramdisk load address
3085 -129	common/image.c		Got ramdisk load address
3086
3087 -130	common/cmd_doc.c	Incorrect FIT image format
3088  131	common/cmd_doc.c	FIT image format OK
3089
3090 -140	common/cmd_ide.c	Incorrect FIT image format
3091  141	common/cmd_ide.c	FIT image format OK
3092
3093 -150	common/cmd_nand.c	Incorrect FIT image format
3094  151	common/cmd_nand.c	FIT image format OK
3095
3096- FIT image support:
3097		CONFIG_FIT
3098		Enable support for the FIT uImage format.
3099
3100		CONFIG_FIT_BEST_MATCH
3101		When no configuration is explicitly selected, default to the
3102		one whose fdt's compatibility field best matches that of
3103		U-Boot itself. A match is considered "best" if it matches the
3104		most specific compatibility entry of U-Boot's fdt's root node.
3105		The order of entries in the configuration's fdt is ignored.
3106
3107		CONFIG_FIT_SIGNATURE
3108		This option enables signature verification of FIT uImages,
3109		using a hash signed and verified using RSA. See
3110		doc/uImage.FIT/signature.txt for more details.
3111
3112- Standalone program support:
3113		CONFIG_STANDALONE_LOAD_ADDR
3114
3115		This option defines a board specific value for the
3116		address where standalone program gets loaded, thus
3117		overwriting the architecture dependent default
3118		settings.
3119
3120- Frame Buffer Address:
3121		CONFIG_FB_ADDR
3122
3123		Define CONFIG_FB_ADDR if you want to use specific
3124		address for frame buffer.  This is typically the case
3125		when using a graphics controller has separate video
3126		memory.  U-Boot will then place the frame buffer at
3127		the given address instead of dynamically reserving it
3128		in system RAM by calling lcd_setmem(), which grabs
3129		the memory for the frame buffer depending on the
3130		configured panel size.
3131
3132		Please see board_init_f function.
3133
3134- Automatic software updates via TFTP server
3135		CONFIG_UPDATE_TFTP
3136		CONFIG_UPDATE_TFTP_CNT_MAX
3137		CONFIG_UPDATE_TFTP_MSEC_MAX
3138
3139		These options enable and control the auto-update feature;
3140		for a more detailed description refer to doc/README.update.
3141
3142- MTD Support (mtdparts command, UBI support)
3143		CONFIG_MTD_DEVICE
3144
3145		Adds the MTD device infrastructure from the Linux kernel.
3146		Needed for mtdparts command support.
3147
3148		CONFIG_MTD_PARTITIONS
3149
3150		Adds the MTD partitioning infrastructure from the Linux
3151		kernel. Needed for UBI support.
3152
3153- UBI support
3154		CONFIG_CMD_UBI
3155
3156		Adds commands for interacting with MTD partitions formatted
3157		with the UBI flash translation layer
3158
3159		Requires also defining CONFIG_RBTREE
3160
3161		CONFIG_UBI_SILENCE_MSG
3162
3163		Make the verbose messages from UBI stop printing.  This leaves
3164		warnings and errors enabled.
3165
3166- UBIFS support
3167		CONFIG_CMD_UBIFS
3168
3169		Adds commands for interacting with UBI volumes formatted as
3170		UBIFS.  UBIFS is read-only in u-boot.
3171
3172		Requires UBI support as well as CONFIG_LZO
3173
3174		CONFIG_UBIFS_SILENCE_MSG
3175
3176		Make the verbose messages from UBIFS stop printing.  This leaves
3177		warnings and errors enabled.
3178
3179- SPL framework
3180		CONFIG_SPL
3181		Enable building of SPL globally.
3182
3183		CONFIG_SPL_LDSCRIPT
3184		LDSCRIPT for linking the SPL binary.
3185
3186		CONFIG_SPL_MAX_FOOTPRINT
3187		Maximum size in memory allocated to the SPL, BSS included.
3188		When defined, the linker checks that the actual memory
3189		used by SPL from _start to __bss_end does not exceed it.
3190		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3191		must not be both defined at the same time.
3192
3193		CONFIG_SPL_MAX_SIZE
3194		Maximum size of the SPL image (text, data, rodata, and
3195		linker lists sections), BSS excluded.
3196		When defined, the linker checks that the actual size does
3197		not exceed it.
3198
3199		CONFIG_SPL_TEXT_BASE
3200		TEXT_BASE for linking the SPL binary.
3201
3202		CONFIG_SPL_RELOC_TEXT_BASE
3203		Address to relocate to.  If unspecified, this is equal to
3204		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3205
3206		CONFIG_SPL_BSS_START_ADDR
3207		Link address for the BSS within the SPL binary.
3208
3209		CONFIG_SPL_BSS_MAX_SIZE
3210		Maximum size in memory allocated to the SPL BSS.
3211		When defined, the linker checks that the actual memory used
3212		by SPL from __bss_start to __bss_end does not exceed it.
3213		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3214		must not be both defined at the same time.
3215
3216		CONFIG_SPL_STACK
3217		Adress of the start of the stack SPL will use
3218
3219		CONFIG_SPL_RELOC_STACK
3220		Adress of the start of the stack SPL will use after
3221		relocation.  If unspecified, this is equal to
3222		CONFIG_SPL_STACK.
3223
3224		CONFIG_SYS_SPL_MALLOC_START
3225		Starting address of the malloc pool used in SPL.
3226
3227		CONFIG_SYS_SPL_MALLOC_SIZE
3228		The size of the malloc pool used in SPL.
3229
3230		CONFIG_SPL_FRAMEWORK
3231		Enable the SPL framework under common/.  This framework
3232		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3233		NAND loading of the Linux Kernel.
3234
3235		CONFIG_SPL_DISPLAY_PRINT
3236		For ARM, enable an optional function to print more information
3237		about the running system.
3238
3239		CONFIG_SPL_INIT_MINIMAL
3240		Arch init code should be built for a very small image
3241
3242		CONFIG_SPL_LIBCOMMON_SUPPORT
3243		Support for common/libcommon.o in SPL binary
3244
3245		CONFIG_SPL_LIBDISK_SUPPORT
3246		Support for disk/libdisk.o in SPL binary
3247
3248		CONFIG_SPL_I2C_SUPPORT
3249		Support for drivers/i2c/libi2c.o in SPL binary
3250
3251		CONFIG_SPL_GPIO_SUPPORT
3252		Support for drivers/gpio/libgpio.o in SPL binary
3253
3254		CONFIG_SPL_MMC_SUPPORT
3255		Support for drivers/mmc/libmmc.o in SPL binary
3256
3257		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3258		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3259		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
3260		Address, size and partition on the MMC to load U-Boot from
3261		when the MMC is being used in raw mode.
3262
3263		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3264		Sector to load kernel uImage from when MMC is being
3265		used in raw mode (for Falcon mode)
3266
3267		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3268		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3269		Sector and number of sectors to load kernel argument
3270		parameters from when MMC is being used in raw mode
3271		(for falcon mode)
3272
3273		CONFIG_SPL_FAT_SUPPORT
3274		Support for fs/fat/libfat.o in SPL binary
3275
3276		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
3277		Filename to read to load U-Boot when reading from FAT
3278
3279		CONFIG_SPL_FAT_LOAD_KERNEL_NAME
3280		Filename to read to load kernel uImage when reading
3281		from FAT (for Falcon mode)
3282
3283		CONFIG_SPL_FAT_LOAD_ARGS_NAME
3284		Filename to read to load kernel argument parameters
3285		when reading from FAT (for Falcon mode)
3286
3287		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3288		Set this for NAND SPL on PPC mpc83xx targets, so that
3289		start.S waits for the rest of the SPL to load before
3290		continuing (the hardware starts execution after just
3291		loading the first page rather than the full 4K).
3292
3293		CONFIG_SPL_NAND_BASE
3294		Include nand_base.c in the SPL.  Requires
3295		CONFIG_SPL_NAND_DRIVERS.
3296
3297		CONFIG_SPL_NAND_DRIVERS
3298		SPL uses normal NAND drivers, not minimal drivers.
3299
3300		CONFIG_SPL_NAND_ECC
3301		Include standard software ECC in the SPL
3302
3303		CONFIG_SPL_NAND_SIMPLE
3304		Support for NAND boot using simple NAND drivers that
3305		expose the cmd_ctrl() interface.
3306
3307		CONFIG_SPL_MPC8XXX_INIT_DDR_SUPPORT
3308		Set for the SPL on PPC mpc8xxx targets, support for
3309		drivers/ddr/fsl/libddr.o in SPL binary.
3310
3311		CONFIG_SPL_COMMON_INIT_DDR
3312		Set for common ddr init with serial presence detect in
3313		SPL binary.
3314
3315		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3316		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3317		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3318		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3319		CONFIG_SYS_NAND_ECCBYTES
3320		Defines the size and behavior of the NAND that SPL uses
3321		to read U-Boot
3322
3323		CONFIG_SPL_NAND_BOOT
3324		Add support NAND boot
3325
3326		CONFIG_SYS_NAND_U_BOOT_OFFS
3327		Location in NAND to read U-Boot from
3328
3329		CONFIG_SYS_NAND_U_BOOT_DST
3330		Location in memory to load U-Boot to
3331
3332		CONFIG_SYS_NAND_U_BOOT_SIZE
3333		Size of image to load
3334
3335		CONFIG_SYS_NAND_U_BOOT_START
3336		Entry point in loaded image to jump to
3337
3338		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3339		Define this if you need to first read the OOB and then the
3340		data. This is used for example on davinci plattforms.
3341
3342		CONFIG_SPL_OMAP3_ID_NAND
3343		Support for an OMAP3-specific set of functions to return the
3344		ID and MFR of the first attached NAND chip, if present.
3345
3346		CONFIG_SPL_SERIAL_SUPPORT
3347		Support for drivers/serial/libserial.o in SPL binary
3348
3349		CONFIG_SPL_SPI_FLASH_SUPPORT
3350		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
3351
3352		CONFIG_SPL_SPI_SUPPORT
3353		Support for drivers/spi/libspi.o in SPL binary
3354
3355		CONFIG_SPL_RAM_DEVICE
3356		Support for running image already present in ram, in SPL binary
3357
3358		CONFIG_SPL_LIBGENERIC_SUPPORT
3359		Support for lib/libgeneric.o in SPL binary
3360
3361		CONFIG_SPL_ENV_SUPPORT
3362		Support for the environment operating in SPL binary
3363
3364		CONFIG_SPL_NET_SUPPORT
3365		Support for the net/libnet.o in SPL binary.
3366		It conflicts with SPL env from storage medium specified by
3367		CONFIG_ENV_IS_xxx but CONFIG_ENV_IS_NOWHERE
3368
3369		CONFIG_SPL_PAD_TO
3370		Image offset to which the SPL should be padded before appending
3371		the SPL payload. By default, this is defined as
3372		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3373		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3374		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3375
3376		CONFIG_SPL_TARGET
3377		Final target image containing SPL and payload.  Some SPLs
3378		use an arch-specific makefile fragment instead, for
3379		example if more than one image needs to be produced.
3380
3381		CONFIG_FIT_SPL_PRINT
3382		Printing information about a FIT image adds quite a bit of
3383		code to SPL. So this is normally disabled in SPL. Use this
3384		option to re-enable it. This will affect the output of the
3385		bootm command when booting a FIT image.
3386
3387- TPL framework
3388		CONFIG_TPL
3389		Enable building of TPL globally.
3390
3391		CONFIG_TPL_PAD_TO
3392		Image offset to which the TPL should be padded before appending
3393		the TPL payload. By default, this is defined as
3394		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3395		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3396		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3397
3398Modem Support:
3399--------------
3400
3401[so far only for SMDK2400 boards]
3402
3403- Modem support enable:
3404		CONFIG_MODEM_SUPPORT
3405
3406- RTS/CTS Flow control enable:
3407		CONFIG_HWFLOW
3408
3409- Modem debug support:
3410		CONFIG_MODEM_SUPPORT_DEBUG
3411
3412		Enables debugging stuff (char screen[1024], dbg())
3413		for modem support. Useful only with BDI2000.
3414
3415- Interrupt support (PPC):
3416
3417		There are common interrupt_init() and timer_interrupt()
3418		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3419		for CPU specific initialization. interrupt_init_cpu()
3420		should set decrementer_count to appropriate value. If
3421		CPU resets decrementer automatically after interrupt
3422		(ppc4xx) it should set decrementer_count to zero.
3423		timer_interrupt() calls timer_interrupt_cpu() for CPU
3424		specific handling. If board has watchdog / status_led
3425		/ other_activity_monitor it works automatically from
3426		general timer_interrupt().
3427
3428- General:
3429
3430		In the target system modem support is enabled when a
3431		specific key (key combination) is pressed during
3432		power-on. Otherwise U-Boot will boot normally
3433		(autoboot). The key_pressed() function is called from
3434		board_init(). Currently key_pressed() is a dummy
3435		function, returning 1 and thus enabling modem
3436		initialization.
3437
3438		If there are no modem init strings in the
3439		environment, U-Boot proceed to autoboot; the
3440		previous output (banner, info printfs) will be
3441		suppressed, though.
3442
3443		See also: doc/README.Modem
3444
3445Board initialization settings:
3446------------------------------
3447
3448During Initialization u-boot calls a number of board specific functions
3449to allow the preparation of board specific prerequisites, e.g. pin setup
3450before drivers are initialized. To enable these callbacks the
3451following configuration macros have to be defined. Currently this is
3452architecture specific, so please check arch/your_architecture/lib/board.c
3453typically in board_init_f() and board_init_r().
3454
3455- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3456- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3457- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3458- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3459
3460Configuration Settings:
3461-----------------------
3462
3463- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3464		undefine this when you're short of memory.
3465
3466- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3467		width of the commands listed in the 'help' command output.
3468
3469- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3470		prompt for user input.
3471
3472- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3473
3474- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3475
3476- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3477
3478- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3479		the application (usually a Linux kernel) when it is
3480		booted
3481
3482- CONFIG_SYS_BAUDRATE_TABLE:
3483		List of legal baudrate settings for this board.
3484
3485- CONFIG_SYS_CONSOLE_INFO_QUIET
3486		Suppress display of console information at boot.
3487
3488- CONFIG_SYS_CONSOLE_IS_IN_ENV
3489		If the board specific function
3490			extern int overwrite_console (void);
3491		returns 1, the stdin, stderr and stdout are switched to the
3492		serial port, else the settings in the environment are used.
3493
3494- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3495		Enable the call to overwrite_console().
3496
3497- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3498		Enable overwrite of previous console environment settings.
3499
3500- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3501		Begin and End addresses of the area used by the
3502		simple memory test.
3503
3504- CONFIG_SYS_ALT_MEMTEST:
3505		Enable an alternate, more extensive memory test.
3506
3507- CONFIG_SYS_MEMTEST_SCRATCH:
3508		Scratch address used by the alternate memory test
3509		You only need to set this if address zero isn't writeable
3510
3511- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
3512		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3513		this specified memory area will get subtracted from the top
3514		(end) of RAM and won't get "touched" at all by U-Boot. By
3515		fixing up gd->ram_size the Linux kernel should gets passed
3516		the now "corrected" memory size and won't touch it either.
3517		This should work for arch/ppc and arch/powerpc. Only Linux
3518		board ports in arch/powerpc with bootwrapper support that
3519		recalculate the memory size from the SDRAM controller setup
3520		will have to get fixed in Linux additionally.
3521
3522		This option can be used as a workaround for the 440EPx/GRx
3523		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3524		be touched.
3525
3526		WARNING: Please make sure that this value is a multiple of
3527		the Linux page size (normally 4k). If this is not the case,
3528		then the end address of the Linux memory will be located at a
3529		non page size aligned address and this could cause major
3530		problems.
3531
3532- CONFIG_SYS_LOADS_BAUD_CHANGE:
3533		Enable temporary baudrate change while serial download
3534
3535- CONFIG_SYS_SDRAM_BASE:
3536		Physical start address of SDRAM. _Must_ be 0 here.
3537
3538- CONFIG_SYS_MBIO_BASE:
3539		Physical start address of Motherboard I/O (if using a
3540		Cogent motherboard)
3541
3542- CONFIG_SYS_FLASH_BASE:
3543		Physical start address of Flash memory.
3544
3545- CONFIG_SYS_MONITOR_BASE:
3546		Physical start address of boot monitor code (set by
3547		make config files to be same as the text base address
3548		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3549		CONFIG_SYS_FLASH_BASE when booting from flash.
3550
3551- CONFIG_SYS_MONITOR_LEN:
3552		Size of memory reserved for monitor code, used to
3553		determine _at_compile_time_ (!) if the environment is
3554		embedded within the U-Boot image, or in a separate
3555		flash sector.
3556
3557- CONFIG_SYS_MALLOC_LEN:
3558		Size of DRAM reserved for malloc() use.
3559
3560- CONFIG_SYS_BOOTM_LEN:
3561		Normally compressed uImages are limited to an
3562		uncompressed size of 8 MBytes. If this is not enough,
3563		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3564		to adjust this setting to your needs.
3565
3566- CONFIG_SYS_BOOTMAPSZ:
3567		Maximum size of memory mapped by the startup code of
3568		the Linux kernel; all data that must be processed by
3569		the Linux kernel (bd_info, boot arguments, FDT blob if
3570		used) must be put below this limit, unless "bootm_low"
3571		environment variable is defined and non-zero. In such case
3572		all data for the Linux kernel must be between "bootm_low"
3573		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3574		variable "bootm_mapsize" will override the value of
3575		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3576		then the value in "bootm_size" will be used instead.
3577
3578- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3579		Enable initrd_high functionality.  If defined then the
3580		initrd_high feature is enabled and the bootm ramdisk subcommand
3581		is enabled.
3582
3583- CONFIG_SYS_BOOT_GET_CMDLINE:
3584		Enables allocating and saving kernel cmdline in space between
3585		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3586
3587- CONFIG_SYS_BOOT_GET_KBD:
3588		Enables allocating and saving a kernel copy of the bd_info in
3589		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3590
3591- CONFIG_SYS_MAX_FLASH_BANKS:
3592		Max number of Flash memory banks
3593
3594- CONFIG_SYS_MAX_FLASH_SECT:
3595		Max number of sectors on a Flash chip
3596
3597- CONFIG_SYS_FLASH_ERASE_TOUT:
3598		Timeout for Flash erase operations (in ms)
3599
3600- CONFIG_SYS_FLASH_WRITE_TOUT:
3601		Timeout for Flash write operations (in ms)
3602
3603- CONFIG_SYS_FLASH_LOCK_TOUT
3604		Timeout for Flash set sector lock bit operation (in ms)
3605
3606- CONFIG_SYS_FLASH_UNLOCK_TOUT
3607		Timeout for Flash clear lock bits operation (in ms)
3608
3609- CONFIG_SYS_FLASH_PROTECTION
3610		If defined, hardware flash sectors protection is used
3611		instead of U-Boot software protection.
3612
3613- CONFIG_SYS_DIRECT_FLASH_TFTP:
3614
3615		Enable TFTP transfers directly to flash memory;
3616		without this option such a download has to be
3617		performed in two steps: (1) download to RAM, and (2)
3618		copy from RAM to flash.
3619
3620		The two-step approach is usually more reliable, since
3621		you can check if the download worked before you erase
3622		the flash, but in some situations (when system RAM is
3623		too limited to allow for a temporary copy of the
3624		downloaded image) this option may be very useful.
3625
3626- CONFIG_SYS_FLASH_CFI:
3627		Define if the flash driver uses extra elements in the
3628		common flash structure for storing flash geometry.
3629
3630- CONFIG_FLASH_CFI_DRIVER
3631		This option also enables the building of the cfi_flash driver
3632		in the drivers directory
3633
3634- CONFIG_FLASH_CFI_MTD
3635		This option enables the building of the cfi_mtd driver
3636		in the drivers directory. The driver exports CFI flash
3637		to the MTD layer.
3638
3639- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3640		Use buffered writes to flash.
3641
3642- CONFIG_FLASH_SPANSION_S29WS_N
3643		s29ws-n MirrorBit flash has non-standard addresses for buffered
3644		write commands.
3645
3646- CONFIG_SYS_FLASH_QUIET_TEST
3647		If this option is defined, the common CFI flash doesn't
3648		print it's warning upon not recognized FLASH banks. This
3649		is useful, if some of the configured banks are only
3650		optionally available.
3651
3652- CONFIG_FLASH_SHOW_PROGRESS
3653		If defined (must be an integer), print out countdown
3654		digits and dots.  Recommended value: 45 (9..1) for 80
3655		column displays, 15 (3..1) for 40 column displays.
3656
3657- CONFIG_FLASH_VERIFY
3658		If defined, the content of the flash (destination) is compared
3659		against the source after the write operation. An error message
3660		will be printed when the contents are not identical.
3661		Please note that this option is useless in nearly all cases,
3662		since such flash programming errors usually are detected earlier
3663		while unprotecting/erasing/programming. Please only enable
3664		this option if you really know what you are doing.
3665
3666- CONFIG_SYS_RX_ETH_BUFFER:
3667		Defines the number of Ethernet receive buffers. On some
3668		Ethernet controllers it is recommended to set this value
3669		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3670		buffers can be full shortly after enabling the interface
3671		on high Ethernet traffic.
3672		Defaults to 4 if not defined.
3673
3674- CONFIG_ENV_MAX_ENTRIES
3675
3676	Maximum number of entries in the hash table that is used
3677	internally to store the environment settings. The default
3678	setting is supposed to be generous and should work in most
3679	cases. This setting can be used to tune behaviour; see
3680	lib/hashtable.c for details.
3681
3682- CONFIG_ENV_FLAGS_LIST_DEFAULT
3683- CONFIG_ENV_FLAGS_LIST_STATIC
3684	Enable validation of the values given to environment variables when
3685	calling env set.  Variables can be restricted to only decimal,
3686	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3687	the variables can also be restricted to IP address or MAC address.
3688
3689	The format of the list is:
3690		type_attribute = [s|d|x|b|i|m]
3691		access_atribute = [a|r|o|c]
3692		attributes = type_attribute[access_atribute]
3693		entry = variable_name[:attributes]
3694		list = entry[,list]
3695
3696	The type attributes are:
3697		s - String (default)
3698		d - Decimal
3699		x - Hexadecimal
3700		b - Boolean ([1yYtT|0nNfF])
3701		i - IP address
3702		m - MAC address
3703
3704	The access attributes are:
3705		a - Any (default)
3706		r - Read-only
3707		o - Write-once
3708		c - Change-default
3709
3710	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3711		Define this to a list (string) to define the ".flags"
3712		envirnoment variable in the default or embedded environment.
3713
3714	- CONFIG_ENV_FLAGS_LIST_STATIC
3715		Define this to a list (string) to define validation that
3716		should be done if an entry is not found in the ".flags"
3717		environment variable.  To override a setting in the static
3718		list, simply add an entry for the same variable name to the
3719		".flags" variable.
3720
3721- CONFIG_ENV_ACCESS_IGNORE_FORCE
3722	If defined, don't allow the -f switch to env set override variable
3723	access flags.
3724
3725- CONFIG_SYS_GENERIC_BOARD
3726	This selects the architecture-generic board system instead of the
3727	architecture-specific board files. It is intended to move boards
3728	to this new framework over time. Defining this will disable the
3729	arch/foo/lib/board.c file and use common/board_f.c and
3730	common/board_r.c instead. To use this option your architecture
3731	must support it (i.e. must define __HAVE_ARCH_GENERIC_BOARD in
3732	its config.mk file). If you find problems enabling this option on
3733	your board please report the problem and send patches!
3734
3735- CONFIG_SYS_SYM_OFFSETS
3736	This is set by architectures that use offsets for link symbols
3737	instead of absolute values. So bss_start is obtained using an
3738	offset _bss_start_ofs from CONFIG_SYS_TEXT_BASE, rather than
3739	directly. You should not need to touch this setting.
3740
3741- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
3742	This is set by OMAP boards for the max time that reset should
3743	be asserted. See doc/README.omap-reset-time for details on how
3744	the value can be calulated on a given board.
3745
3746The following definitions that deal with the placement and management
3747of environment data (variable area); in general, we support the
3748following configurations:
3749
3750- CONFIG_BUILD_ENVCRC:
3751
3752	Builds up envcrc with the target environment so that external utils
3753	may easily extract it and embed it in final U-Boot images.
3754
3755- CONFIG_ENV_IS_IN_FLASH:
3756
3757	Define this if the environment is in flash memory.
3758
3759	a) The environment occupies one whole flash sector, which is
3760	   "embedded" in the text segment with the U-Boot code. This
3761	   happens usually with "bottom boot sector" or "top boot
3762	   sector" type flash chips, which have several smaller
3763	   sectors at the start or the end. For instance, such a
3764	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3765	   such a case you would place the environment in one of the
3766	   4 kB sectors - with U-Boot code before and after it. With
3767	   "top boot sector" type flash chips, you would put the
3768	   environment in one of the last sectors, leaving a gap
3769	   between U-Boot and the environment.
3770
3771	- CONFIG_ENV_OFFSET:
3772
3773	   Offset of environment data (variable area) to the
3774	   beginning of flash memory; for instance, with bottom boot
3775	   type flash chips the second sector can be used: the offset
3776	   for this sector is given here.
3777
3778	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3779
3780	- CONFIG_ENV_ADDR:
3781
3782	   This is just another way to specify the start address of
3783	   the flash sector containing the environment (instead of
3784	   CONFIG_ENV_OFFSET).
3785
3786	- CONFIG_ENV_SECT_SIZE:
3787
3788	   Size of the sector containing the environment.
3789
3790
3791	b) Sometimes flash chips have few, equal sized, BIG sectors.
3792	   In such a case you don't want to spend a whole sector for
3793	   the environment.
3794
3795	- CONFIG_ENV_SIZE:
3796
3797	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3798	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3799	   of this flash sector for the environment. This saves
3800	   memory for the RAM copy of the environment.
3801
3802	   It may also save flash memory if you decide to use this
3803	   when your environment is "embedded" within U-Boot code,
3804	   since then the remainder of the flash sector could be used
3805	   for U-Boot code. It should be pointed out that this is
3806	   STRONGLY DISCOURAGED from a robustness point of view:
3807	   updating the environment in flash makes it always
3808	   necessary to erase the WHOLE sector. If something goes
3809	   wrong before the contents has been restored from a copy in
3810	   RAM, your target system will be dead.
3811
3812	- CONFIG_ENV_ADDR_REDUND
3813	  CONFIG_ENV_SIZE_REDUND
3814
3815	   These settings describe a second storage area used to hold
3816	   a redundant copy of the environment data, so that there is
3817	   a valid backup copy in case there is a power failure during
3818	   a "saveenv" operation.
3819
3820BE CAREFUL! Any changes to the flash layout, and some changes to the
3821source code will make it necessary to adapt <board>/u-boot.lds*
3822accordingly!
3823
3824
3825- CONFIG_ENV_IS_IN_NVRAM:
3826
3827	Define this if you have some non-volatile memory device
3828	(NVRAM, battery buffered SRAM) which you want to use for the
3829	environment.
3830
3831	- CONFIG_ENV_ADDR:
3832	- CONFIG_ENV_SIZE:
3833
3834	  These two #defines are used to determine the memory area you
3835	  want to use for environment. It is assumed that this memory
3836	  can just be read and written to, without any special
3837	  provision.
3838
3839BE CAREFUL! The first access to the environment happens quite early
3840in U-Boot initalization (when we try to get the setting of for the
3841console baudrate). You *MUST* have mapped your NVRAM area then, or
3842U-Boot will hang.
3843
3844Please note that even with NVRAM we still use a copy of the
3845environment in RAM: we could work on NVRAM directly, but we want to
3846keep settings there always unmodified except somebody uses "saveenv"
3847to save the current settings.
3848
3849
3850- CONFIG_ENV_IS_IN_EEPROM:
3851
3852	Use this if you have an EEPROM or similar serial access
3853	device and a driver for it.
3854
3855	- CONFIG_ENV_OFFSET:
3856	- CONFIG_ENV_SIZE:
3857
3858	  These two #defines specify the offset and size of the
3859	  environment area within the total memory of your EEPROM.
3860
3861	- CONFIG_SYS_I2C_EEPROM_ADDR:
3862	  If defined, specified the chip address of the EEPROM device.
3863	  The default address is zero.
3864
3865	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3866	  If defined, the number of bits used to address bytes in a
3867	  single page in the EEPROM device.  A 64 byte page, for example
3868	  would require six bits.
3869
3870	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3871	  If defined, the number of milliseconds to delay between
3872	  page writes.	The default is zero milliseconds.
3873
3874	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3875	  The length in bytes of the EEPROM memory array address.  Note
3876	  that this is NOT the chip address length!
3877
3878	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3879	  EEPROM chips that implement "address overflow" are ones
3880	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3881	  address and the extra bits end up in the "chip address" bit
3882	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3883	  byte chips.
3884
3885	  Note that we consider the length of the address field to
3886	  still be one byte because the extra address bits are hidden
3887	  in the chip address.
3888
3889	- CONFIG_SYS_EEPROM_SIZE:
3890	  The size in bytes of the EEPROM device.
3891
3892	- CONFIG_ENV_EEPROM_IS_ON_I2C
3893	  define this, if you have I2C and SPI activated, and your
3894	  EEPROM, which holds the environment, is on the I2C bus.
3895
3896	- CONFIG_I2C_ENV_EEPROM_BUS
3897	  if you have an Environment on an EEPROM reached over
3898	  I2C muxes, you can define here, how to reach this
3899	  EEPROM. For example:
3900
3901	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
3902
3903	  EEPROM which holds the environment, is reached over
3904	  a pca9547 i2c mux with address 0x70, channel 3.
3905
3906- CONFIG_ENV_IS_IN_DATAFLASH:
3907
3908	Define this if you have a DataFlash memory device which you
3909	want to use for the environment.
3910
3911	- CONFIG_ENV_OFFSET:
3912	- CONFIG_ENV_ADDR:
3913	- CONFIG_ENV_SIZE:
3914
3915	  These three #defines specify the offset and size of the
3916	  environment area within the total memory of your DataFlash placed
3917	  at the specified address.
3918
3919- CONFIG_ENV_IS_IN_REMOTE:
3920
3921	Define this if you have a remote memory space which you
3922	want to use for the local device's environment.
3923
3924	- CONFIG_ENV_ADDR:
3925	- CONFIG_ENV_SIZE:
3926
3927	  These two #defines specify the address and size of the
3928	  environment area within the remote memory space. The
3929	  local device can get the environment from remote memory
3930	  space by SRIO or PCIE links.
3931
3932BE CAREFUL! For some special cases, the local device can not use
3933"saveenv" command. For example, the local device will get the
3934environment stored in a remote NOR flash by SRIO or PCIE link,
3935but it can not erase, write this NOR flash by SRIO or PCIE interface.
3936
3937- CONFIG_ENV_IS_IN_NAND:
3938
3939	Define this if you have a NAND device which you want to use
3940	for the environment.
3941
3942	- CONFIG_ENV_OFFSET:
3943	- CONFIG_ENV_SIZE:
3944
3945	  These two #defines specify the offset and size of the environment
3946	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
3947	  aligned to an erase block boundary.
3948
3949	- CONFIG_ENV_OFFSET_REDUND (optional):
3950
3951	  This setting describes a second storage area of CONFIG_ENV_SIZE
3952	  size used to hold a redundant copy of the environment data, so
3953	  that there is a valid backup copy in case there is a power failure
3954	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
3955	  aligned to an erase block boundary.
3956
3957	- CONFIG_ENV_RANGE (optional):
3958
3959	  Specifies the length of the region in which the environment
3960	  can be written.  This should be a multiple of the NAND device's
3961	  block size.  Specifying a range with more erase blocks than
3962	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
3963	  the range to be avoided.
3964
3965	- CONFIG_ENV_OFFSET_OOB (optional):
3966
3967	  Enables support for dynamically retrieving the offset of the
3968	  environment from block zero's out-of-band data.  The
3969	  "nand env.oob" command can be used to record this offset.
3970	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
3971	  using CONFIG_ENV_OFFSET_OOB.
3972
3973- CONFIG_NAND_ENV_DST
3974
3975	Defines address in RAM to which the nand_spl code should copy the
3976	environment. If redundant environment is used, it will be copied to
3977	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3978
3979- CONFIG_ENV_IS_IN_UBI:
3980
3981	Define this if you have an UBI volume that you want to use for the
3982	environment.  This has the benefit of wear-leveling the environment
3983	accesses, which is important on NAND.
3984
3985	- CONFIG_ENV_UBI_PART:
3986
3987	  Define this to a string that is the mtd partition containing the UBI.
3988
3989	- CONFIG_ENV_UBI_VOLUME:
3990
3991	  Define this to the name of the volume that you want to store the
3992	  environment in.
3993
3994	- CONFIG_ENV_UBI_VOLUME_REDUND:
3995
3996	  Define this to the name of another volume to store a second copy of
3997	  the environment in.  This will enable redundant environments in UBI.
3998	  It is assumed that both volumes are in the same MTD partition.
3999
4000	- CONFIG_UBI_SILENCE_MSG
4001	- CONFIG_UBIFS_SILENCE_MSG
4002
4003	  You will probably want to define these to avoid a really noisy system
4004	  when storing the env in UBI.
4005
4006- CONFIG_ENV_IS_IN_MMC:
4007
4008	Define this if you have an MMC device which you want to use for the
4009	environment.
4010
4011	- CONFIG_SYS_MMC_ENV_DEV:
4012
4013	  Specifies which MMC device the environment is stored in.
4014
4015	- CONFIG_SYS_MMC_ENV_PART (optional):
4016
4017	  Specifies which MMC partition the environment is stored in. If not
4018	  set, defaults to partition 0, the user area. Common values might be
4019	  1 (first MMC boot partition), 2 (second MMC boot partition).
4020
4021	- CONFIG_ENV_OFFSET:
4022	- CONFIG_ENV_SIZE:
4023
4024	  These two #defines specify the offset and size of the environment
4025	  area within the specified MMC device.
4026
4027	  If offset is positive (the usual case), it is treated as relative to
4028	  the start of the MMC partition. If offset is negative, it is treated
4029	  as relative to the end of the MMC partition. This can be useful if
4030	  your board may be fitted with different MMC devices, which have
4031	  different sizes for the MMC partitions, and you always want the
4032	  environment placed at the very end of the partition, to leave the
4033	  maximum possible space before it, to store other data.
4034
4035	  These two values are in units of bytes, but must be aligned to an
4036	  MMC sector boundary.
4037
4038	- CONFIG_ENV_OFFSET_REDUND (optional):
4039
4040	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
4041	  hold a redundant copy of the environment data. This provides a
4042	  valid backup copy in case the other copy is corrupted, e.g. due
4043	  to a power failure during a "saveenv" operation.
4044
4045	  This value may also be positive or negative; this is handled in the
4046	  same way as CONFIG_ENV_OFFSET.
4047
4048	  This value is also in units of bytes, but must also be aligned to
4049	  an MMC sector boundary.
4050
4051	- CONFIG_ENV_SIZE_REDUND (optional):
4052
4053	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
4054	  set. If this value is set, it must be set to the same value as
4055	  CONFIG_ENV_SIZE.
4056
4057- CONFIG_SYS_SPI_INIT_OFFSET
4058
4059	Defines offset to the initial SPI buffer area in DPRAM. The
4060	area is used at an early stage (ROM part) if the environment
4061	is configured to reside in the SPI EEPROM: We need a 520 byte
4062	scratch DPRAM area. It is used between the two initialization
4063	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
4064	to be a good choice since it makes it far enough from the
4065	start of the data area as well as from the stack pointer.
4066
4067Please note that the environment is read-only until the monitor
4068has been relocated to RAM and a RAM copy of the environment has been
4069created; also, when using EEPROM you will have to use getenv_f()
4070until then to read environment variables.
4071
4072The environment is protected by a CRC32 checksum. Before the monitor
4073is relocated into RAM, as a result of a bad CRC you will be working
4074with the compiled-in default environment - *silently*!!! [This is
4075necessary, because the first environment variable we need is the
4076"baudrate" setting for the console - if we have a bad CRC, we don't
4077have any device yet where we could complain.]
4078
4079Note: once the monitor has been relocated, then it will complain if
4080the default environment is used; a new CRC is computed as soon as you
4081use the "saveenv" command to store a valid environment.
4082
4083- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
4084		Echo the inverted Ethernet link state to the fault LED.
4085
4086		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
4087		      also needs to be defined.
4088
4089- CONFIG_SYS_FAULT_MII_ADDR:
4090		MII address of the PHY to check for the Ethernet link state.
4091
4092- CONFIG_NS16550_MIN_FUNCTIONS:
4093		Define this if you desire to only have use of the NS16550_init
4094		and NS16550_putc functions for the serial driver located at
4095		drivers/serial/ns16550.c.  This option is useful for saving
4096		space for already greatly restricted images, including but not
4097		limited to NAND_SPL configurations.
4098
4099- CONFIG_DISPLAY_BOARDINFO
4100		Display information about the board that U-Boot is running on
4101		when U-Boot starts up. The board function checkboard() is called
4102		to do this.
4103
4104- CONFIG_DISPLAY_BOARDINFO_LATE
4105		Similar to the previous option, but display this information
4106		later, once stdio is running and output goes to the LCD, if
4107		present.
4108
4109Low Level (hardware related) configuration options:
4110---------------------------------------------------
4111
4112- CONFIG_SYS_CACHELINE_SIZE:
4113		Cache Line Size of the CPU.
4114
4115- CONFIG_SYS_DEFAULT_IMMR:
4116		Default address of the IMMR after system reset.
4117
4118		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4119		and RPXsuper) to be able to adjust the position of
4120		the IMMR register after a reset.
4121
4122- CONFIG_SYS_CCSRBAR_DEFAULT:
4123		Default (power-on reset) physical address of CCSR on Freescale
4124		PowerPC SOCs.
4125
4126- CONFIG_SYS_CCSRBAR:
4127		Virtual address of CCSR.  On a 32-bit build, this is typically
4128		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4129
4130		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4131		for cross-platform code that uses that macro instead.
4132
4133- CONFIG_SYS_CCSRBAR_PHYS:
4134		Physical address of CCSR.  CCSR can be relocated to a new
4135		physical address, if desired.  In this case, this macro should
4136		be set to that address.	 Otherwise, it should be set to the
4137		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
4138		is typically relocated on 36-bit builds.  It is recommended
4139		that this macro be defined via the _HIGH and _LOW macros:
4140
4141		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4142			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4143
4144- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4145		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
4146		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
4147		used in assembly code, so it must not contain typecasts or
4148		integer size suffixes (e.g. "ULL").
4149
4150- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4151		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
4152		used in assembly code, so it must not contain typecasts or
4153		integer size suffixes (e.g. "ULL").
4154
4155- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
4156		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4157		forced to a value that ensures that CCSR is not relocated.
4158
4159- Floppy Disk Support:
4160		CONFIG_SYS_FDC_DRIVE_NUMBER
4161
4162		the default drive number (default value 0)
4163
4164		CONFIG_SYS_ISA_IO_STRIDE
4165
4166		defines the spacing between FDC chipset registers
4167		(default value 1)
4168
4169		CONFIG_SYS_ISA_IO_OFFSET
4170
4171		defines the offset of register from address. It
4172		depends on which part of the data bus is connected to
4173		the FDC chipset. (default value 0)
4174
4175		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4176		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4177		default value.
4178
4179		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4180		fdc_hw_init() is called at the beginning of the FDC
4181		setup. fdc_hw_init() must be provided by the board
4182		source code. It is used to make hardware dependant
4183		initializations.
4184
4185- CONFIG_IDE_AHB:
4186		Most IDE controllers were designed to be connected with PCI
4187		interface. Only few of them were designed for AHB interface.
4188		When software is doing ATA command and data transfer to
4189		IDE devices through IDE-AHB controller, some additional
4190		registers accessing to these kind of IDE-AHB controller
4191		is requierd.
4192
4193- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4194		DO NOT CHANGE unless you know exactly what you're
4195		doing! (11-4) [MPC8xx/82xx systems only]
4196
4197- CONFIG_SYS_INIT_RAM_ADDR:
4198
4199		Start address of memory area that can be used for
4200		initial data and stack; please note that this must be
4201		writable memory that is working WITHOUT special
4202		initialization, i. e. you CANNOT use normal RAM which
4203		will become available only after programming the
4204		memory controller and running certain initialization
4205		sequences.
4206
4207		U-Boot uses the following memory types:
4208		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4209		- MPC824X: data cache
4210		- PPC4xx:  data cache
4211
4212- CONFIG_SYS_GBL_DATA_OFFSET:
4213
4214		Offset of the initial data structure in the memory
4215		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4216		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4217		data is located at the end of the available space
4218		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4219		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
4220		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4221		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4222
4223	Note:
4224		On the MPC824X (or other systems that use the data
4225		cache for initial memory) the address chosen for
4226		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4227		point to an otherwise UNUSED address space between
4228		the top of RAM and the start of the PCI space.
4229
4230- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4231
4232- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4233
4234- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4235
4236- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4237
4238- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4239
4240- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4241
4242- CONFIG_SYS_OR_TIMING_SDRAM:
4243		SDRAM timing
4244
4245- CONFIG_SYS_MAMR_PTA:
4246		periodic timer for refresh
4247
4248- CONFIG_SYS_DER:	Debug Event Register (37-47)
4249
4250- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4251  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4252  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4253  CONFIG_SYS_BR1_PRELIM:
4254		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4255
4256- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4257  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4258  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4259		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4260
4261- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4262  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4263		Machine Mode Register and Memory Periodic Timer
4264		Prescaler definitions (SDRAM timing)
4265
4266- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4267		enable I2C microcode relocation patch (MPC8xx);
4268		define relocation offset in DPRAM [DSP2]
4269
4270- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4271		enable SMC microcode relocation patch (MPC8xx);
4272		define relocation offset in DPRAM [SMC1]
4273
4274- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4275		enable SPI microcode relocation patch (MPC8xx);
4276		define relocation offset in DPRAM [SCC4]
4277
4278- CONFIG_SYS_USE_OSCCLK:
4279		Use OSCM clock mode on MBX8xx board. Be careful,
4280		wrong setting might damage your board. Read
4281		doc/README.MBX before setting this variable!
4282
4283- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4284		Offset of the bootmode word in DPRAM used by post
4285		(Power On Self Tests). This definition overrides
4286		#define'd default value in commproc.h resp.
4287		cpm_8260.h.
4288
4289- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4290  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4291  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4292  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4293  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4294  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4295  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4296  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4297		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4298
4299- CONFIG_PCI_DISABLE_PCIE:
4300		Disable PCI-Express on systems where it is supported but not
4301		required.
4302
4303- CONFIG_PCI_ENUM_ONLY
4304		Only scan through and get the devices on the busses.
4305		Don't do any setup work, presumably because someone or
4306		something has already done it, and we don't need to do it
4307		a second time.	Useful for platforms that are pre-booted
4308		by coreboot or similar.
4309
4310- CONFIG_PCI_INDIRECT_BRIDGE:
4311		Enable support for indirect PCI bridges.
4312
4313- CONFIG_SYS_SRIO:
4314		Chip has SRIO or not
4315
4316- CONFIG_SRIO1:
4317		Board has SRIO 1 port available
4318
4319- CONFIG_SRIO2:
4320		Board has SRIO 2 port available
4321
4322- CONFIG_SRIO_PCIE_BOOT_MASTER
4323		Board can support master function for Boot from SRIO and PCIE
4324
4325- CONFIG_SYS_SRIOn_MEM_VIRT:
4326		Virtual Address of SRIO port 'n' memory region
4327
4328- CONFIG_SYS_SRIOn_MEM_PHYS:
4329		Physical Address of SRIO port 'n' memory region
4330
4331- CONFIG_SYS_SRIOn_MEM_SIZE:
4332		Size of SRIO port 'n' memory region
4333
4334- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4335		Defined to tell the NAND controller that the NAND chip is using
4336		a 16 bit bus.
4337		Not all NAND drivers use this symbol.
4338		Example of drivers that use it:
4339		- drivers/mtd/nand/ndfc.c
4340		- drivers/mtd/nand/mxc_nand.c
4341
4342- CONFIG_SYS_NDFC_EBC0_CFG
4343		Sets the EBC0_CFG register for the NDFC. If not defined
4344		a default value will be used.
4345
4346- CONFIG_SPD_EEPROM
4347		Get DDR timing information from an I2C EEPROM. Common
4348		with pluggable memory modules such as SODIMMs
4349
4350  SPD_EEPROM_ADDRESS
4351		I2C address of the SPD EEPROM
4352
4353- CONFIG_SYS_SPD_BUS_NUM
4354		If SPD EEPROM is on an I2C bus other than the first
4355		one, specify here. Note that the value must resolve
4356		to something your driver can deal with.
4357
4358- CONFIG_SYS_DDR_RAW_TIMING
4359		Get DDR timing information from other than SPD. Common with
4360		soldered DDR chips onboard without SPD. DDR raw timing
4361		parameters are extracted from datasheet and hard-coded into
4362		header files or board specific files.
4363
4364- CONFIG_FSL_DDR_INTERACTIVE
4365		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4366
4367- CONFIG_SYS_83XX_DDR_USES_CS0
4368		Only for 83xx systems. If specified, then DDR should
4369		be configured using CS0 and CS1 instead of CS2 and CS3.
4370
4371- CONFIG_ETHER_ON_FEC[12]
4372		Define to enable FEC[12] on a 8xx series processor.
4373
4374- CONFIG_FEC[12]_PHY
4375		Define to the hardcoded PHY address which corresponds
4376		to the given FEC; i. e.
4377			#define CONFIG_FEC1_PHY 4
4378		means that the PHY with address 4 is connected to FEC1
4379
4380		When set to -1, means to probe for first available.
4381
4382- CONFIG_FEC[12]_PHY_NORXERR
4383		The PHY does not have a RXERR line (RMII only).
4384		(so program the FEC to ignore it).
4385
4386- CONFIG_RMII
4387		Enable RMII mode for all FECs.
4388		Note that this is a global option, we can't
4389		have one FEC in standard MII mode and another in RMII mode.
4390
4391- CONFIG_CRC32_VERIFY
4392		Add a verify option to the crc32 command.
4393		The syntax is:
4394
4395		=> crc32 -v <address> <count> <crc32>
4396
4397		Where address/count indicate a memory area
4398		and crc32 is the correct crc32 which the
4399		area should have.
4400
4401- CONFIG_LOOPW
4402		Add the "loopw" memory command. This only takes effect if
4403		the memory commands are activated globally (CONFIG_CMD_MEM).
4404
4405- CONFIG_MX_CYCLIC
4406		Add the "mdc" and "mwc" memory commands. These are cyclic
4407		"md/mw" commands.
4408		Examples:
4409
4410		=> mdc.b 10 4 500
4411		This command will print 4 bytes (10,11,12,13) each 500 ms.
4412
4413		=> mwc.l 100 12345678 10
4414		This command will write 12345678 to address 100 all 10 ms.
4415
4416		This only takes effect if the memory commands are activated
4417		globally (CONFIG_CMD_MEM).
4418
4419- CONFIG_SKIP_LOWLEVEL_INIT
4420		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4421		low level initializations (like setting up the memory
4422		controller) are omitted and/or U-Boot does not
4423		relocate itself into RAM.
4424
4425		Normally this variable MUST NOT be defined. The only
4426		exception is when U-Boot is loaded (to RAM) by some
4427		other boot loader or by a debugger which performs
4428		these initializations itself.
4429
4430- CONFIG_SPL_BUILD
4431		Modifies the behaviour of start.S when compiling a loader
4432		that is executed before the actual U-Boot. E.g. when
4433		compiling a NAND SPL.
4434
4435- CONFIG_TPL_BUILD
4436		Modifies the behaviour of start.S  when compiling a loader
4437		that is executed after the SPL and before the actual U-Boot.
4438		It is loaded by the SPL.
4439
4440- CONFIG_SYS_MPC85XX_NO_RESETVEC
4441		Only for 85xx systems. If this variable is specified, the section
4442		.resetvec is not kept and the section .bootpg is placed in the
4443		previous 4k of the .text section.
4444
4445- CONFIG_ARCH_MAP_SYSMEM
4446		Generally U-Boot (and in particular the md command) uses
4447		effective address. It is therefore not necessary to regard
4448		U-Boot address as virtual addresses that need to be translated
4449		to physical addresses. However, sandbox requires this, since
4450		it maintains its own little RAM buffer which contains all
4451		addressable memory. This option causes some memory accesses
4452		to be mapped through map_sysmem() / unmap_sysmem().
4453
4454- CONFIG_USE_ARCH_MEMCPY
4455  CONFIG_USE_ARCH_MEMSET
4456		If these options are used a optimized version of memcpy/memset will
4457		be used if available. These functions may be faster under some
4458		conditions but may increase the binary size.
4459
4460- CONFIG_X86_RESET_VECTOR
4461		If defined, the x86 reset vector code is included. This is not
4462		needed when U-Boot is running from Coreboot.
4463
4464- CONFIG_SYS_MPUCLK
4465		Defines the MPU clock speed (in MHz).
4466
4467		NOTE : currently only supported on AM335x platforms.
4468
4469- CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
4470		Enables the RTC32K OSC on AM33xx based plattforms
4471
4472Freescale QE/FMAN Firmware Support:
4473-----------------------------------
4474
4475The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4476loading of "firmware", which is encoded in the QE firmware binary format.
4477This firmware often needs to be loaded during U-Boot booting, so macros
4478are used to identify the storage device (NOR flash, SPI, etc) and the address
4479within that device.
4480
4481- CONFIG_SYS_QE_FMAN_FW_ADDR
4482	The address in the storage device where the firmware is located.  The
4483	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4484	is also specified.
4485
4486- CONFIG_SYS_QE_FMAN_FW_LENGTH
4487	The maximum possible size of the firmware.  The firmware binary format
4488	has a field that specifies the actual size of the firmware, but it
4489	might not be possible to read any part of the firmware unless some
4490	local storage is allocated to hold the entire firmware first.
4491
4492- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4493	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4494	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4495	virtual address in NOR flash.
4496
4497- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4498	Specifies that QE/FMAN firmware is located in NAND flash.
4499	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4500
4501- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4502	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4503	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4504
4505- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
4506	Specifies that QE/FMAN firmware is located on the primary SPI
4507	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4508
4509- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4510	Specifies that QE/FMAN firmware is located in the remote (master)
4511	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4512	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4513	window->master inbound window->master LAW->the ucode address in
4514	master's memory space.
4515
4516Building the Software:
4517======================
4518
4519Building U-Boot has been tested in several native build environments
4520and in many different cross environments. Of course we cannot support
4521all possibly existing versions of cross development tools in all
4522(potentially obsolete) versions. In case of tool chain problems we
4523recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4524which is extensively used to build and test U-Boot.
4525
4526If you are not using a native environment, it is assumed that you
4527have GNU cross compiling tools available in your path. In this case,
4528you must set the environment variable CROSS_COMPILE in your shell.
4529Note that no changes to the Makefile or any other source files are
4530necessary. For example using the ELDK on a 4xx CPU, please enter:
4531
4532	$ CROSS_COMPILE=ppc_4xx-
4533	$ export CROSS_COMPILE
4534
4535Note: If you wish to generate Windows versions of the utilities in
4536      the tools directory you can use the MinGW toolchain
4537      (http://www.mingw.org).  Set your HOST tools to the MinGW
4538      toolchain and execute 'make tools'.  For example:
4539
4540       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4541
4542      Binaries such as tools/mkimage.exe will be created which can
4543      be executed on computers running Windows.
4544
4545U-Boot is intended to be simple to build. After installing the
4546sources you must configure U-Boot for one specific board type. This
4547is done by typing:
4548
4549	make NAME_config
4550
4551where "NAME_config" is the name of one of the existing configu-
4552rations; see boards.cfg for supported names.
4553
4554Note: for some board special configuration names may exist; check if
4555      additional information is available from the board vendor; for
4556      instance, the TQM823L systems are available without (standard)
4557      or with LCD support. You can select such additional "features"
4558      when choosing the configuration, i. e.
4559
4560      make TQM823L_config
4561	- will configure for a plain TQM823L, i. e. no LCD support
4562
4563      make TQM823L_LCD_config
4564	- will configure for a TQM823L with U-Boot console on LCD
4565
4566      etc.
4567
4568
4569Finally, type "make all", and you should get some working U-Boot
4570images ready for download to / installation on your system:
4571
4572- "u-boot.bin" is a raw binary image
4573- "u-boot" is an image in ELF binary format
4574- "u-boot.srec" is in Motorola S-Record format
4575
4576By default the build is performed locally and the objects are saved
4577in the source directory. One of the two methods can be used to change
4578this behavior and build U-Boot to some external directory:
4579
45801. Add O= to the make command line invocations:
4581
4582	make O=/tmp/build distclean
4583	make O=/tmp/build NAME_config
4584	make O=/tmp/build all
4585
45862. Set environment variable BUILD_DIR to point to the desired location:
4587
4588	export BUILD_DIR=/tmp/build
4589	make distclean
4590	make NAME_config
4591	make all
4592
4593Note that the command line "O=" setting overrides the BUILD_DIR environment
4594variable.
4595
4596
4597Please be aware that the Makefiles assume you are using GNU make, so
4598for instance on NetBSD you might need to use "gmake" instead of
4599native "make".
4600
4601
4602If the system board that you have is not listed, then you will need
4603to port U-Boot to your hardware platform. To do this, follow these
4604steps:
4605
46061.  Add a new configuration option for your board to the toplevel
4607    "boards.cfg" file, using the existing entries as examples.
4608    Follow the instructions there to keep the boards in order.
46092.  Create a new directory to hold your board specific code. Add any
4610    files you need. In your board directory, you will need at least
4611    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
46123.  Create a new configuration file "include/configs/<board>.h" for
4613    your board
46143.  If you're porting U-Boot to a new CPU, then also create a new
4615    directory to hold your CPU specific code. Add any files you need.
46164.  Run "make <board>_config" with your new name.
46175.  Type "make", and you should get a working "u-boot.srec" file
4618    to be installed on your target system.
46196.  Debug and solve any problems that might arise.
4620    [Of course, this last step is much harder than it sounds.]
4621
4622
4623Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4624==============================================================
4625
4626If you have modified U-Boot sources (for instance added a new board
4627or support for new devices, a new CPU, etc.) you are expected to
4628provide feedback to the other developers. The feedback normally takes
4629the form of a "patch", i. e. a context diff against a certain (latest
4630official or latest in the git repository) version of U-Boot sources.
4631
4632But before you submit such a patch, please verify that your modifi-
4633cation did not break existing code. At least make sure that *ALL* of
4634the supported boards compile WITHOUT ANY compiler warnings. To do so,
4635just run the "MAKEALL" script, which will configure and build U-Boot
4636for ALL supported system. Be warned, this will take a while. You can
4637select which (cross) compiler to use by passing a `CROSS_COMPILE'
4638environment variable to the script, i. e. to use the ELDK cross tools
4639you can type
4640
4641	CROSS_COMPILE=ppc_8xx- MAKEALL
4642
4643or to build on a native PowerPC system you can type
4644
4645	CROSS_COMPILE=' ' MAKEALL
4646
4647When using the MAKEALL script, the default behaviour is to build
4648U-Boot in the source directory. This location can be changed by
4649setting the BUILD_DIR environment variable. Also, for each target
4650built, the MAKEALL script saves two log files (<target>.ERR and
4651<target>.MAKEALL) in the <source dir>/LOG directory. This default
4652location can be changed by setting the MAKEALL_LOGDIR environment
4653variable. For example:
4654
4655	export BUILD_DIR=/tmp/build
4656	export MAKEALL_LOGDIR=/tmp/log
4657	CROSS_COMPILE=ppc_8xx- MAKEALL
4658
4659With the above settings build objects are saved in the /tmp/build,
4660log files are saved in the /tmp/log and the source tree remains clean
4661during the whole build process.
4662
4663
4664See also "U-Boot Porting Guide" below.
4665
4666
4667Monitor Commands - Overview:
4668============================
4669
4670go	- start application at address 'addr'
4671run	- run commands in an environment variable
4672bootm	- boot application image from memory
4673bootp	- boot image via network using BootP/TFTP protocol
4674bootz   - boot zImage from memory
4675tftpboot- boot image via network using TFTP protocol
4676	       and env variables "ipaddr" and "serverip"
4677	       (and eventually "gatewayip")
4678tftpput - upload a file via network using TFTP protocol
4679rarpboot- boot image via network using RARP/TFTP protocol
4680diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4681loads	- load S-Record file over serial line
4682loadb	- load binary file over serial line (kermit mode)
4683md	- memory display
4684mm	- memory modify (auto-incrementing)
4685nm	- memory modify (constant address)
4686mw	- memory write (fill)
4687cp	- memory copy
4688cmp	- memory compare
4689crc32	- checksum calculation
4690i2c	- I2C sub-system
4691sspi	- SPI utility commands
4692base	- print or set address offset
4693printenv- print environment variables
4694setenv	- set environment variables
4695saveenv - save environment variables to persistent storage
4696protect - enable or disable FLASH write protection
4697erase	- erase FLASH memory
4698flinfo	- print FLASH memory information
4699nand	- NAND memory operations (see doc/README.nand)
4700bdinfo	- print Board Info structure
4701iminfo	- print header information for application image
4702coninfo - print console devices and informations
4703ide	- IDE sub-system
4704loop	- infinite loop on address range
4705loopw	- infinite write loop on address range
4706mtest	- simple RAM test
4707icache	- enable or disable instruction cache
4708dcache	- enable or disable data cache
4709reset	- Perform RESET of the CPU
4710echo	- echo args to console
4711version - print monitor version
4712help	- print online help
4713?	- alias for 'help'
4714
4715
4716Monitor Commands - Detailed Description:
4717========================================
4718
4719TODO.
4720
4721For now: just type "help <command>".
4722
4723
4724Environment Variables:
4725======================
4726
4727U-Boot supports user configuration using Environment Variables which
4728can be made persistent by saving to Flash memory.
4729
4730Environment Variables are set using "setenv", printed using
4731"printenv", and saved to Flash using "saveenv". Using "setenv"
4732without a value can be used to delete a variable from the
4733environment. As long as you don't save the environment you are
4734working with an in-memory copy. In case the Flash area containing the
4735environment is erased by accident, a default environment is provided.
4736
4737Some configuration options can be set using Environment Variables.
4738
4739List of environment variables (most likely not complete):
4740
4741  baudrate	- see CONFIG_BAUDRATE
4742
4743  bootdelay	- see CONFIG_BOOTDELAY
4744
4745  bootcmd	- see CONFIG_BOOTCOMMAND
4746
4747  bootargs	- Boot arguments when booting an RTOS image
4748
4749  bootfile	- Name of the image to load with TFTP
4750
4751  bootm_low	- Memory range available for image processing in the bootm
4752		  command can be restricted. This variable is given as
4753		  a hexadecimal number and defines lowest address allowed
4754		  for use by the bootm command. See also "bootm_size"
4755		  environment variable. Address defined by "bootm_low" is
4756		  also the base of the initial memory mapping for the Linux
4757		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
4758		  bootm_mapsize.
4759
4760  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
4761		  This variable is given as a hexadecimal number and it
4762		  defines the size of the memory region starting at base
4763		  address bootm_low that is accessible by the Linux kernel
4764		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
4765		  as the default value if it is defined, and bootm_size is
4766		  used otherwise.
4767
4768  bootm_size	- Memory range available for image processing in the bootm
4769		  command can be restricted. This variable is given as
4770		  a hexadecimal number and defines the size of the region
4771		  allowed for use by the bootm command. See also "bootm_low"
4772		  environment variable.
4773
4774  updatefile	- Location of the software update file on a TFTP server, used
4775		  by the automatic software update feature. Please refer to
4776		  documentation in doc/README.update for more details.
4777
4778  autoload	- if set to "no" (any string beginning with 'n'),
4779		  "bootp" will just load perform a lookup of the
4780		  configuration from the BOOTP server, but not try to
4781		  load any image using TFTP
4782
4783  autostart	- if set to "yes", an image loaded using the "bootp",
4784		  "rarpboot", "tftpboot" or "diskboot" commands will
4785		  be automatically started (by internally calling
4786		  "bootm")
4787
4788		  If set to "no", a standalone image passed to the
4789		  "bootm" command will be copied to the load address
4790		  (and eventually uncompressed), but NOT be started.
4791		  This can be used to load and uncompress arbitrary
4792		  data.
4793
4794  fdt_high	- if set this restricts the maximum address that the
4795		  flattened device tree will be copied into upon boot.
4796		  For example, if you have a system with 1 GB memory
4797		  at physical address 0x10000000, while Linux kernel
4798		  only recognizes the first 704 MB as low memory, you
4799		  may need to set fdt_high as 0x3C000000 to have the
4800		  device tree blob be copied to the maximum address
4801		  of the 704 MB low memory, so that Linux kernel can
4802		  access it during the boot procedure.
4803
4804		  If this is set to the special value 0xFFFFFFFF then
4805		  the fdt will not be copied at all on boot.  For this
4806		  to work it must reside in writable memory, have
4807		  sufficient padding on the end of it for u-boot to
4808		  add the information it needs into it, and the memory
4809		  must be accessible by the kernel.
4810
4811  fdtcontroladdr- if set this is the address of the control flattened
4812		  device tree used by U-Boot when CONFIG_OF_CONTROL is
4813		  defined.
4814
4815  i2cfast	- (PPC405GP|PPC405EP only)
4816		  if set to 'y' configures Linux I2C driver for fast
4817		  mode (400kHZ). This environment variable is used in
4818		  initialization code. So, for changes to be effective
4819		  it must be saved and board must be reset.
4820
4821  initrd_high	- restrict positioning of initrd images:
4822		  If this variable is not set, initrd images will be
4823		  copied to the highest possible address in RAM; this
4824		  is usually what you want since it allows for
4825		  maximum initrd size. If for some reason you want to
4826		  make sure that the initrd image is loaded below the
4827		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
4828		  variable to a value of "no" or "off" or "0".
4829		  Alternatively, you can set it to a maximum upper
4830		  address to use (U-Boot will still check that it
4831		  does not overwrite the U-Boot stack and data).
4832
4833		  For instance, when you have a system with 16 MB
4834		  RAM, and want to reserve 4 MB from use by Linux,
4835		  you can do this by adding "mem=12M" to the value of
4836		  the "bootargs" variable. However, now you must make
4837		  sure that the initrd image is placed in the first
4838		  12 MB as well - this can be done with
4839
4840		  setenv initrd_high 00c00000
4841
4842		  If you set initrd_high to 0xFFFFFFFF, this is an
4843		  indication to U-Boot that all addresses are legal
4844		  for the Linux kernel, including addresses in flash
4845		  memory. In this case U-Boot will NOT COPY the
4846		  ramdisk at all. This may be useful to reduce the
4847		  boot time on your system, but requires that this
4848		  feature is supported by your Linux kernel.
4849
4850  ipaddr	- IP address; needed for tftpboot command
4851
4852  loadaddr	- Default load address for commands like "bootp",
4853		  "rarpboot", "tftpboot", "loadb" or "diskboot"
4854
4855  loads_echo	- see CONFIG_LOADS_ECHO
4856
4857  serverip	- TFTP server IP address; needed for tftpboot command
4858
4859  bootretry	- see CONFIG_BOOT_RETRY_TIME
4860
4861  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
4862
4863  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
4864
4865  ethprime	- controls which interface is used first.
4866
4867  ethact	- controls which interface is currently active.
4868		  For example you can do the following
4869
4870		  => setenv ethact FEC
4871		  => ping 192.168.0.1 # traffic sent on FEC
4872		  => setenv ethact SCC
4873		  => ping 10.0.0.1 # traffic sent on SCC
4874
4875  ethrotate	- When set to "no" U-Boot does not go through all
4876		  available network interfaces.
4877		  It just stays at the currently selected interface.
4878
4879  netretry	- When set to "no" each network operation will
4880		  either succeed or fail without retrying.
4881		  When set to "once" the network operation will
4882		  fail when all the available network interfaces
4883		  are tried once without success.
4884		  Useful on scripts which control the retry operation
4885		  themselves.
4886
4887  npe_ucode	- set load address for the NPE microcode
4888
4889  silent_linux  - If set then linux will be told to boot silently, by
4890		  changing the console to be empty. If "yes" it will be
4891		  made silent. If "no" it will not be made silent. If
4892		  unset, then it will be made silent if the U-Boot console
4893		  is silent.
4894
4895  tftpsrcport	- If this is set, the value is used for TFTP's
4896		  UDP source port.
4897
4898  tftpdstport	- If this is set, the value is used for TFTP's UDP
4899		  destination port instead of the Well Know Port 69.
4900
4901  tftpblocksize - Block size to use for TFTP transfers; if not set,
4902		  we use the TFTP server's default block size
4903
4904  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
4905		  seconds, minimum value is 1000 = 1 second). Defines
4906		  when a packet is considered to be lost so it has to
4907		  be retransmitted. The default is 5000 = 5 seconds.
4908		  Lowering this value may make downloads succeed
4909		  faster in networks with high packet loss rates or
4910		  with unreliable TFTP servers.
4911
4912  vlan		- When set to a value < 4095 the traffic over
4913		  Ethernet is encapsulated/received over 802.1q
4914		  VLAN tagged frames.
4915
4916The following image location variables contain the location of images
4917used in booting. The "Image" column gives the role of the image and is
4918not an environment variable name. The other columns are environment
4919variable names. "File Name" gives the name of the file on a TFTP
4920server, "RAM Address" gives the location in RAM the image will be
4921loaded to, and "Flash Location" gives the image's address in NOR
4922flash or offset in NAND flash.
4923
4924*Note* - these variables don't have to be defined for all boards, some
4925boards currenlty use other variables for these purposes, and some
4926boards use these variables for other purposes.
4927
4928Image		    File Name	     RAM Address       Flash Location
4929-----		    ---------	     -----------       --------------
4930u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
4931Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
4932device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
4933ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
4934
4935The following environment variables may be used and automatically
4936updated by the network boot commands ("bootp" and "rarpboot"),
4937depending the information provided by your boot server:
4938
4939  bootfile	- see above
4940  dnsip		- IP address of your Domain Name Server
4941  dnsip2	- IP address of your secondary Domain Name Server
4942  gatewayip	- IP address of the Gateway (Router) to use
4943  hostname	- Target hostname
4944  ipaddr	- see above
4945  netmask	- Subnet Mask
4946  rootpath	- Pathname of the root filesystem on the NFS server
4947  serverip	- see above
4948
4949
4950There are two special Environment Variables:
4951
4952  serial#	- contains hardware identification information such
4953		  as type string and/or serial number
4954  ethaddr	- Ethernet address
4955
4956These variables can be set only once (usually during manufacturing of
4957the board). U-Boot refuses to delete or overwrite these variables
4958once they have been set once.
4959
4960
4961Further special Environment Variables:
4962
4963  ver		- Contains the U-Boot version string as printed
4964		  with the "version" command. This variable is
4965		  readonly (see CONFIG_VERSION_VARIABLE).
4966
4967
4968Please note that changes to some configuration parameters may take
4969only effect after the next boot (yes, that's just like Windoze :-).
4970
4971
4972Callback functions for environment variables:
4973---------------------------------------------
4974
4975For some environment variables, the behavior of u-boot needs to change
4976when their values are changed.  This functionailty allows functions to
4977be associated with arbitrary variables.  On creation, overwrite, or
4978deletion, the callback will provide the opportunity for some side
4979effect to happen or for the change to be rejected.
4980
4981The callbacks are named and associated with a function using the
4982U_BOOT_ENV_CALLBACK macro in your board or driver code.
4983
4984These callbacks are associated with variables in one of two ways.  The
4985static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
4986in the board configuration to a string that defines a list of
4987associations.  The list must be in the following format:
4988
4989	entry = variable_name[:callback_name]
4990	list = entry[,list]
4991
4992If the callback name is not specified, then the callback is deleted.
4993Spaces are also allowed anywhere in the list.
4994
4995Callbacks can also be associated by defining the ".callbacks" variable
4996with the same list format above.  Any association in ".callbacks" will
4997override any association in the static list. You can define
4998CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
4999".callbacks" envirnoment variable in the default or embedded environment.
5000
5001
5002Command Line Parsing:
5003=====================
5004
5005There are two different command line parsers available with U-Boot:
5006the old "simple" one, and the much more powerful "hush" shell:
5007
5008Old, simple command line parser:
5009--------------------------------
5010
5011- supports environment variables (through setenv / saveenv commands)
5012- several commands on one line, separated by ';'
5013- variable substitution using "... ${name} ..." syntax
5014- special characters ('$', ';') can be escaped by prefixing with '\',
5015  for example:
5016	setenv bootcmd bootm \${address}
5017- You can also escape text by enclosing in single apostrophes, for example:
5018	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
5019
5020Hush shell:
5021-----------
5022
5023- similar to Bourne shell, with control structures like
5024  if...then...else...fi, for...do...done; while...do...done,
5025  until...do...done, ...
5026- supports environment ("global") variables (through setenv / saveenv
5027  commands) and local shell variables (through standard shell syntax
5028  "name=value"); only environment variables can be used with "run"
5029  command
5030
5031General rules:
5032--------------
5033
5034(1) If a command line (or an environment variable executed by a "run"
5035    command) contains several commands separated by semicolon, and
5036    one of these commands fails, then the remaining commands will be
5037    executed anyway.
5038
5039(2) If you execute several variables with one call to run (i. e.
5040    calling run with a list of variables as arguments), any failing
5041    command will cause "run" to terminate, i. e. the remaining
5042    variables are not executed.
5043
5044Note for Redundant Ethernet Interfaces:
5045=======================================
5046
5047Some boards come with redundant Ethernet interfaces; U-Boot supports
5048such configurations and is capable of automatic selection of a
5049"working" interface when needed. MAC assignment works as follows:
5050
5051Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
5052MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
5053"eth1addr" (=>eth1), "eth2addr", ...
5054
5055If the network interface stores some valid MAC address (for instance
5056in SROM), this is used as default address if there is NO correspon-
5057ding setting in the environment; if the corresponding environment
5058variable is set, this overrides the settings in the card; that means:
5059
5060o If the SROM has a valid MAC address, and there is no address in the
5061  environment, the SROM's address is used.
5062
5063o If there is no valid address in the SROM, and a definition in the
5064  environment exists, then the value from the environment variable is
5065  used.
5066
5067o If both the SROM and the environment contain a MAC address, and
5068  both addresses are the same, this MAC address is used.
5069
5070o If both the SROM and the environment contain a MAC address, and the
5071  addresses differ, the value from the environment is used and a
5072  warning is printed.
5073
5074o If neither SROM nor the environment contain a MAC address, an error
5075  is raised.
5076
5077If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
5078will be programmed into hardware as part of the initialization process.	 This
5079may be skipped by setting the appropriate 'ethmacskip' environment variable.
5080The naming convention is as follows:
5081"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
5082
5083Image Formats:
5084==============
5085
5086U-Boot is capable of booting (and performing other auxiliary operations on)
5087images in two formats:
5088
5089New uImage format (FIT)
5090-----------------------
5091
5092Flexible and powerful format based on Flattened Image Tree -- FIT (similar
5093to Flattened Device Tree). It allows the use of images with multiple
5094components (several kernels, ramdisks, etc.), with contents protected by
5095SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
5096
5097
5098Old uImage format
5099-----------------
5100
5101Old image format is based on binary files which can be basically anything,
5102preceded by a special header; see the definitions in include/image.h for
5103details; basically, the header defines the following image properties:
5104
5105* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
5106  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
5107  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
5108  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
5109  INTEGRITY).
5110* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
5111  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
5112  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
5113* Compression Type (uncompressed, gzip, bzip2)
5114* Load Address
5115* Entry Point
5116* Image Name
5117* Image Timestamp
5118
5119The header is marked by a special Magic Number, and both the header
5120and the data portions of the image are secured against corruption by
5121CRC32 checksums.
5122
5123
5124Linux Support:
5125==============
5126
5127Although U-Boot should support any OS or standalone application
5128easily, the main focus has always been on Linux during the design of
5129U-Boot.
5130
5131U-Boot includes many features that so far have been part of some
5132special "boot loader" code within the Linux kernel. Also, any
5133"initrd" images to be used are no longer part of one big Linux image;
5134instead, kernel and "initrd" are separate images. This implementation
5135serves several purposes:
5136
5137- the same features can be used for other OS or standalone
5138  applications (for instance: using compressed images to reduce the
5139  Flash memory footprint)
5140
5141- it becomes much easier to port new Linux kernel versions because
5142  lots of low-level, hardware dependent stuff are done by U-Boot
5143
5144- the same Linux kernel image can now be used with different "initrd"
5145  images; of course this also means that different kernel images can
5146  be run with the same "initrd". This makes testing easier (you don't
5147  have to build a new "zImage.initrd" Linux image when you just
5148  change a file in your "initrd"). Also, a field-upgrade of the
5149  software is easier now.
5150
5151
5152Linux HOWTO:
5153============
5154
5155Porting Linux to U-Boot based systems:
5156---------------------------------------
5157
5158U-Boot cannot save you from doing all the necessary modifications to
5159configure the Linux device drivers for use with your target hardware
5160(no, we don't intend to provide a full virtual machine interface to
5161Linux :-).
5162
5163But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
5164
5165Just make sure your machine specific header file (for instance
5166include/asm-ppc/tqm8xx.h) includes the same definition of the Board
5167Information structure as we define in include/asm-<arch>/u-boot.h,
5168and make sure that your definition of IMAP_ADDR uses the same value
5169as your U-Boot configuration in CONFIG_SYS_IMMR.
5170
5171
5172Configuring the Linux kernel:
5173-----------------------------
5174
5175No specific requirements for U-Boot. Make sure you have some root
5176device (initial ramdisk, NFS) for your target system.
5177
5178
5179Building a Linux Image:
5180-----------------------
5181
5182With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5183not used. If you use recent kernel source, a new build target
5184"uImage" will exist which automatically builds an image usable by
5185U-Boot. Most older kernels also have support for a "pImage" target,
5186which was introduced for our predecessor project PPCBoot and uses a
5187100% compatible format.
5188
5189Example:
5190
5191	make TQM850L_config
5192	make oldconfig
5193	make dep
5194	make uImage
5195
5196The "uImage" build target uses a special tool (in 'tools/mkimage') to
5197encapsulate a compressed Linux kernel image with header	 information,
5198CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5199
5200* build a standard "vmlinux" kernel image (in ELF binary format):
5201
5202* convert the kernel into a raw binary image:
5203
5204	${CROSS_COMPILE}-objcopy -O binary \
5205				 -R .note -R .comment \
5206				 -S vmlinux linux.bin
5207
5208* compress the binary image:
5209
5210	gzip -9 linux.bin
5211
5212* package compressed binary image for U-Boot:
5213
5214	mkimage -A ppc -O linux -T kernel -C gzip \
5215		-a 0 -e 0 -n "Linux Kernel Image" \
5216		-d linux.bin.gz uImage
5217
5218
5219The "mkimage" tool can also be used to create ramdisk images for use
5220with U-Boot, either separated from the Linux kernel image, or
5221combined into one file. "mkimage" encapsulates the images with a 64
5222byte header containing information about target architecture,
5223operating system, image type, compression method, entry points, time
5224stamp, CRC32 checksums, etc.
5225
5226"mkimage" can be called in two ways: to verify existing images and
5227print the header information, or to build new images.
5228
5229In the first form (with "-l" option) mkimage lists the information
5230contained in the header of an existing U-Boot image; this includes
5231checksum verification:
5232
5233	tools/mkimage -l image
5234	  -l ==> list image header information
5235
5236The second form (with "-d" option) is used to build a U-Boot image
5237from a "data file" which is used as image payload:
5238
5239	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5240		      -n name -d data_file image
5241	  -A ==> set architecture to 'arch'
5242	  -O ==> set operating system to 'os'
5243	  -T ==> set image type to 'type'
5244	  -C ==> set compression type 'comp'
5245	  -a ==> set load address to 'addr' (hex)
5246	  -e ==> set entry point to 'ep' (hex)
5247	  -n ==> set image name to 'name'
5248	  -d ==> use image data from 'datafile'
5249
5250Right now, all Linux kernels for PowerPC systems use the same load
5251address (0x00000000), but the entry point address depends on the
5252kernel version:
5253
5254- 2.2.x kernels have the entry point at 0x0000000C,
5255- 2.3.x and later kernels have the entry point at 0x00000000.
5256
5257So a typical call to build a U-Boot image would read:
5258
5259	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5260	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5261	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5262	> examples/uImage.TQM850L
5263	Image Name:   2.4.4 kernel for TQM850L
5264	Created:      Wed Jul 19 02:34:59 2000
5265	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5266	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5267	Load Address: 0x00000000
5268	Entry Point:  0x00000000
5269
5270To verify the contents of the image (or check for corruption):
5271
5272	-> tools/mkimage -l examples/uImage.TQM850L
5273	Image Name:   2.4.4 kernel for TQM850L
5274	Created:      Wed Jul 19 02:34:59 2000
5275	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5276	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5277	Load Address: 0x00000000
5278	Entry Point:  0x00000000
5279
5280NOTE: for embedded systems where boot time is critical you can trade
5281speed for memory and install an UNCOMPRESSED image instead: this
5282needs more space in Flash, but boots much faster since it does not
5283need to be uncompressed:
5284
5285	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5286	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5287	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5288	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5289	> examples/uImage.TQM850L-uncompressed
5290	Image Name:   2.4.4 kernel for TQM850L
5291	Created:      Wed Jul 19 02:34:59 2000
5292	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5293	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5294	Load Address: 0x00000000
5295	Entry Point:  0x00000000
5296
5297
5298Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5299when your kernel is intended to use an initial ramdisk:
5300
5301	-> tools/mkimage -n 'Simple Ramdisk Image' \
5302	> -A ppc -O linux -T ramdisk -C gzip \
5303	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5304	Image Name:   Simple Ramdisk Image
5305	Created:      Wed Jan 12 14:01:50 2000
5306	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5307	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5308	Load Address: 0x00000000
5309	Entry Point:  0x00000000
5310
5311The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
5312option performs the converse operation of the mkimage's second form (the "-d"
5313option). Given an image built by mkimage, the dumpimage extracts a "data file"
5314from the image:
5315
5316	tools/dumpimage -i image -p position data_file
5317	  -i ==> extract from the 'image' a specific 'data_file', \
5318	   indexed by 'position'
5319
5320
5321Installing a Linux Image:
5322-------------------------
5323
5324To downloading a U-Boot image over the serial (console) interface,
5325you must convert the image to S-Record format:
5326
5327	objcopy -I binary -O srec examples/image examples/image.srec
5328
5329The 'objcopy' does not understand the information in the U-Boot
5330image header, so the resulting S-Record file will be relative to
5331address 0x00000000. To load it to a given address, you need to
5332specify the target address as 'offset' parameter with the 'loads'
5333command.
5334
5335Example: install the image to address 0x40100000 (which on the
5336TQM8xxL is in the first Flash bank):
5337
5338	=> erase 40100000 401FFFFF
5339
5340	.......... done
5341	Erased 8 sectors
5342
5343	=> loads 40100000
5344	## Ready for S-Record download ...
5345	~>examples/image.srec
5346	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5347	...
5348	15989 15990 15991 15992
5349	[file transfer complete]
5350	[connected]
5351	## Start Addr = 0x00000000
5352
5353
5354You can check the success of the download using the 'iminfo' command;
5355this includes a checksum verification so you can be sure no data
5356corruption happened:
5357
5358	=> imi 40100000
5359
5360	## Checking Image at 40100000 ...
5361	   Image Name:	 2.2.13 for initrd on TQM850L
5362	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5363	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5364	   Load Address: 00000000
5365	   Entry Point:	 0000000c
5366	   Verifying Checksum ... OK
5367
5368
5369Boot Linux:
5370-----------
5371
5372The "bootm" command is used to boot an application that is stored in
5373memory (RAM or Flash). In case of a Linux kernel image, the contents
5374of the "bootargs" environment variable is passed to the kernel as
5375parameters. You can check and modify this variable using the
5376"printenv" and "setenv" commands:
5377
5378
5379	=> printenv bootargs
5380	bootargs=root=/dev/ram
5381
5382	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5383
5384	=> printenv bootargs
5385	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5386
5387	=> bootm 40020000
5388	## Booting Linux kernel at 40020000 ...
5389	   Image Name:	 2.2.13 for NFS on TQM850L
5390	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5391	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5392	   Load Address: 00000000
5393	   Entry Point:	 0000000c
5394	   Verifying Checksum ... OK
5395	   Uncompressing Kernel Image ... OK
5396	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
5397	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5398	time_init: decrementer frequency = 187500000/60
5399	Calibrating delay loop... 49.77 BogoMIPS
5400	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5401	...
5402
5403If you want to boot a Linux kernel with initial RAM disk, you pass
5404the memory addresses of both the kernel and the initrd image (PPBCOOT
5405format!) to the "bootm" command:
5406
5407	=> imi 40100000 40200000
5408
5409	## Checking Image at 40100000 ...
5410	   Image Name:	 2.2.13 for initrd on TQM850L
5411	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5412	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5413	   Load Address: 00000000
5414	   Entry Point:	 0000000c
5415	   Verifying Checksum ... OK
5416
5417	## Checking Image at 40200000 ...
5418	   Image Name:	 Simple Ramdisk Image
5419	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5420	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5421	   Load Address: 00000000
5422	   Entry Point:	 00000000
5423	   Verifying Checksum ... OK
5424
5425	=> bootm 40100000 40200000
5426	## Booting Linux kernel at 40100000 ...
5427	   Image Name:	 2.2.13 for initrd on TQM850L
5428	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5429	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5430	   Load Address: 00000000
5431	   Entry Point:	 0000000c
5432	   Verifying Checksum ... OK
5433	   Uncompressing Kernel Image ... OK
5434	## Loading RAMDisk Image at 40200000 ...
5435	   Image Name:	 Simple Ramdisk Image
5436	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5437	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5438	   Load Address: 00000000
5439	   Entry Point:	 00000000
5440	   Verifying Checksum ... OK
5441	   Loading Ramdisk ... OK
5442	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
5443	Boot arguments: root=/dev/ram
5444	time_init: decrementer frequency = 187500000/60
5445	Calibrating delay loop... 49.77 BogoMIPS
5446	...
5447	RAMDISK: Compressed image found at block 0
5448	VFS: Mounted root (ext2 filesystem).
5449
5450	bash#
5451
5452Boot Linux and pass a flat device tree:
5453-----------
5454
5455First, U-Boot must be compiled with the appropriate defines. See the section
5456titled "Linux Kernel Interface" above for a more in depth explanation. The
5457following is an example of how to start a kernel and pass an updated
5458flat device tree:
5459
5460=> print oftaddr
5461oftaddr=0x300000
5462=> print oft
5463oft=oftrees/mpc8540ads.dtb
5464=> tftp $oftaddr $oft
5465Speed: 1000, full duplex
5466Using TSEC0 device
5467TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5468Filename 'oftrees/mpc8540ads.dtb'.
5469Load address: 0x300000
5470Loading: #
5471done
5472Bytes transferred = 4106 (100a hex)
5473=> tftp $loadaddr $bootfile
5474Speed: 1000, full duplex
5475Using TSEC0 device
5476TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5477Filename 'uImage'.
5478Load address: 0x200000
5479Loading:############
5480done
5481Bytes transferred = 1029407 (fb51f hex)
5482=> print loadaddr
5483loadaddr=200000
5484=> print oftaddr
5485oftaddr=0x300000
5486=> bootm $loadaddr - $oftaddr
5487## Booting image at 00200000 ...
5488   Image Name:	 Linux-2.6.17-dirty
5489   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5490   Data Size:	 1029343 Bytes = 1005.2 kB
5491   Load Address: 00000000
5492   Entry Point:	 00000000
5493   Verifying Checksum ... OK
5494   Uncompressing Kernel Image ... OK
5495Booting using flat device tree at 0x300000
5496Using MPC85xx ADS machine description
5497Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5498[snip]
5499
5500
5501More About U-Boot Image Types:
5502------------------------------
5503
5504U-Boot supports the following image types:
5505
5506   "Standalone Programs" are directly runnable in the environment
5507	provided by U-Boot; it is expected that (if they behave
5508	well) you can continue to work in U-Boot after return from
5509	the Standalone Program.
5510   "OS Kernel Images" are usually images of some Embedded OS which
5511	will take over control completely. Usually these programs
5512	will install their own set of exception handlers, device
5513	drivers, set up the MMU, etc. - this means, that you cannot
5514	expect to re-enter U-Boot except by resetting the CPU.
5515   "RAMDisk Images" are more or less just data blocks, and their
5516	parameters (address, size) are passed to an OS kernel that is
5517	being started.
5518   "Multi-File Images" contain several images, typically an OS
5519	(Linux) kernel image and one or more data images like
5520	RAMDisks. This construct is useful for instance when you want
5521	to boot over the network using BOOTP etc., where the boot
5522	server provides just a single image file, but you want to get
5523	for instance an OS kernel and a RAMDisk image.
5524
5525	"Multi-File Images" start with a list of image sizes, each
5526	image size (in bytes) specified by an "uint32_t" in network
5527	byte order. This list is terminated by an "(uint32_t)0".
5528	Immediately after the terminating 0 follow the images, one by
5529	one, all aligned on "uint32_t" boundaries (size rounded up to
5530	a multiple of 4 bytes).
5531
5532   "Firmware Images" are binary images containing firmware (like
5533	U-Boot or FPGA images) which usually will be programmed to
5534	flash memory.
5535
5536   "Script files" are command sequences that will be executed by
5537	U-Boot's command interpreter; this feature is especially
5538	useful when you configure U-Boot to use a real shell (hush)
5539	as command interpreter.
5540
5541Booting the Linux zImage:
5542-------------------------
5543
5544On some platforms, it's possible to boot Linux zImage. This is done
5545using the "bootz" command. The syntax of "bootz" command is the same
5546as the syntax of "bootm" command.
5547
5548Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5549kernel with raw initrd images. The syntax is slightly different, the
5550address of the initrd must be augmented by it's size, in the following
5551format: "<initrd addres>:<initrd size>".
5552
5553
5554Standalone HOWTO:
5555=================
5556
5557One of the features of U-Boot is that you can dynamically load and
5558run "standalone" applications, which can use some resources of
5559U-Boot like console I/O functions or interrupt services.
5560
5561Two simple examples are included with the sources:
5562
5563"Hello World" Demo:
5564-------------------
5565
5566'examples/hello_world.c' contains a small "Hello World" Demo
5567application; it is automatically compiled when you build U-Boot.
5568It's configured to run at address 0x00040004, so you can play with it
5569like that:
5570
5571	=> loads
5572	## Ready for S-Record download ...
5573	~>examples/hello_world.srec
5574	1 2 3 4 5 6 7 8 9 10 11 ...
5575	[file transfer complete]
5576	[connected]
5577	## Start Addr = 0x00040004
5578
5579	=> go 40004 Hello World! This is a test.
5580	## Starting application at 0x00040004 ...
5581	Hello World
5582	argc = 7
5583	argv[0] = "40004"
5584	argv[1] = "Hello"
5585	argv[2] = "World!"
5586	argv[3] = "This"
5587	argv[4] = "is"
5588	argv[5] = "a"
5589	argv[6] = "test."
5590	argv[7] = "<NULL>"
5591	Hit any key to exit ...
5592
5593	## Application terminated, rc = 0x0
5594
5595Another example, which demonstrates how to register a CPM interrupt
5596handler with the U-Boot code, can be found in 'examples/timer.c'.
5597Here, a CPM timer is set up to generate an interrupt every second.
5598The interrupt service routine is trivial, just printing a '.'
5599character, but this is just a demo program. The application can be
5600controlled by the following keys:
5601
5602	? - print current values og the CPM Timer registers
5603	b - enable interrupts and start timer
5604	e - stop timer and disable interrupts
5605	q - quit application
5606
5607	=> loads
5608	## Ready for S-Record download ...
5609	~>examples/timer.srec
5610	1 2 3 4 5 6 7 8 9 10 11 ...
5611	[file transfer complete]
5612	[connected]
5613	## Start Addr = 0x00040004
5614
5615	=> go 40004
5616	## Starting application at 0x00040004 ...
5617	TIMERS=0xfff00980
5618	Using timer 1
5619	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5620
5621Hit 'b':
5622	[q, b, e, ?] Set interval 1000000 us
5623	Enabling timer
5624Hit '?':
5625	[q, b, e, ?] ........
5626	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5627Hit '?':
5628	[q, b, e, ?] .
5629	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5630Hit '?':
5631	[q, b, e, ?] .
5632	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
5633Hit '?':
5634	[q, b, e, ?] .
5635	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
5636Hit 'e':
5637	[q, b, e, ?] ...Stopping timer
5638Hit 'q':
5639	[q, b, e, ?] ## Application terminated, rc = 0x0
5640
5641
5642Minicom warning:
5643================
5644
5645Over time, many people have reported problems when trying to use the
5646"minicom" terminal emulation program for serial download. I (wd)
5647consider minicom to be broken, and recommend not to use it. Under
5648Unix, I recommend to use C-Kermit for general purpose use (and
5649especially for kermit binary protocol download ("loadb" command), and
5650use "cu" for S-Record download ("loads" command).  See
5651http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
5652for help with kermit.
5653
5654
5655Nevertheless, if you absolutely want to use it try adding this
5656configuration to your "File transfer protocols" section:
5657
5658	   Name	   Program			Name U/D FullScr IO-Red. Multi
5659	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5660	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5661
5662
5663NetBSD Notes:
5664=============
5665
5666Starting at version 0.9.2, U-Boot supports NetBSD both as host
5667(build U-Boot) and target system (boots NetBSD/mpc8xx).
5668
5669Building requires a cross environment; it is known to work on
5670NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5671need gmake since the Makefiles are not compatible with BSD make).
5672Note that the cross-powerpc package does not install include files;
5673attempting to build U-Boot will fail because <machine/ansi.h> is
5674missing.  This file has to be installed and patched manually:
5675
5676	# cd /usr/pkg/cross/powerpc-netbsd/include
5677	# mkdir powerpc
5678	# ln -s powerpc machine
5679	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5680	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5681
5682Native builds *don't* work due to incompatibilities between native
5683and U-Boot include files.
5684
5685Booting assumes that (the first part of) the image booted is a
5686stage-2 loader which in turn loads and then invokes the kernel
5687proper. Loader sources will eventually appear in the NetBSD source
5688tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5689meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5690
5691
5692Implementation Internals:
5693=========================
5694
5695The following is not intended to be a complete description of every
5696implementation detail. However, it should help to understand the
5697inner workings of U-Boot and make it easier to port it to custom
5698hardware.
5699
5700
5701Initial Stack, Global Data:
5702---------------------------
5703
5704The implementation of U-Boot is complicated by the fact that U-Boot
5705starts running out of ROM (flash memory), usually without access to
5706system RAM (because the memory controller is not initialized yet).
5707This means that we don't have writable Data or BSS segments, and BSS
5708is not initialized as zero. To be able to get a C environment working
5709at all, we have to allocate at least a minimal stack. Implementation
5710options for this are defined and restricted by the CPU used: Some CPU
5711models provide on-chip memory (like the IMMR area on MPC8xx and
5712MPC826x processors), on others (parts of) the data cache can be
5713locked as (mis-) used as memory, etc.
5714
5715	Chris Hallinan posted a good summary of these issues to the
5716	U-Boot mailing list:
5717
5718	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
5719	From: "Chris Hallinan" <clh@net1plus.com>
5720	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
5721	...
5722
5723	Correct me if I'm wrong, folks, but the way I understand it
5724	is this: Using DCACHE as initial RAM for Stack, etc, does not
5725	require any physical RAM backing up the cache. The cleverness
5726	is that the cache is being used as a temporary supply of
5727	necessary storage before the SDRAM controller is setup. It's
5728	beyond the scope of this list to explain the details, but you
5729	can see how this works by studying the cache architecture and
5730	operation in the architecture and processor-specific manuals.
5731
5732	OCM is On Chip Memory, which I believe the 405GP has 4K. It
5733	is another option for the system designer to use as an
5734	initial stack/RAM area prior to SDRAM being available. Either
5735	option should work for you. Using CS 4 should be fine if your
5736	board designers haven't used it for something that would
5737	cause you grief during the initial boot! It is frequently not
5738	used.
5739
5740	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
5741	with your processor/board/system design. The default value
5742	you will find in any recent u-boot distribution in
5743	walnut.h should work for you. I'd set it to a value larger
5744	than your SDRAM module. If you have a 64MB SDRAM module, set
5745	it above 400_0000. Just make sure your board has no resources
5746	that are supposed to respond to that address! That code in
5747	start.S has been around a while and should work as is when
5748	you get the config right.
5749
5750	-Chris Hallinan
5751	DS4.COM, Inc.
5752
5753It is essential to remember this, since it has some impact on the C
5754code for the initialization procedures:
5755
5756* Initialized global data (data segment) is read-only. Do not attempt
5757  to write it.
5758
5759* Do not use any uninitialized global data (or implicitely initialized
5760  as zero data - BSS segment) at all - this is undefined, initiali-
5761  zation is performed later (when relocating to RAM).
5762
5763* Stack space is very limited. Avoid big data buffers or things like
5764  that.
5765
5766Having only the stack as writable memory limits means we cannot use
5767normal global data to share information beween the code. But it
5768turned out that the implementation of U-Boot can be greatly
5769simplified by making a global data structure (gd_t) available to all
5770functions. We could pass a pointer to this data as argument to _all_
5771functions, but this would bloat the code. Instead we use a feature of
5772the GCC compiler (Global Register Variables) to share the data: we
5773place a pointer (gd) to the global data into a register which we
5774reserve for this purpose.
5775
5776When choosing a register for such a purpose we are restricted by the
5777relevant  (E)ABI  specifications for the current architecture, and by
5778GCC's implementation.
5779
5780For PowerPC, the following registers have specific use:
5781	R1:	stack pointer
5782	R2:	reserved for system use
5783	R3-R4:	parameter passing and return values
5784	R5-R10: parameter passing
5785	R13:	small data area pointer
5786	R30:	GOT pointer
5787	R31:	frame pointer
5788
5789	(U-Boot also uses R12 as internal GOT pointer. r12
5790	is a volatile register so r12 needs to be reset when
5791	going back and forth between asm and C)
5792
5793    ==> U-Boot will use R2 to hold a pointer to the global data
5794
5795    Note: on PPC, we could use a static initializer (since the
5796    address of the global data structure is known at compile time),
5797    but it turned out that reserving a register results in somewhat
5798    smaller code - although the code savings are not that big (on
5799    average for all boards 752 bytes for the whole U-Boot image,
5800    624 text + 127 data).
5801
5802On Blackfin, the normal C ABI (except for P3) is followed as documented here:
5803	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
5804
5805    ==> U-Boot will use P3 to hold a pointer to the global data
5806
5807On ARM, the following registers are used:
5808
5809	R0:	function argument word/integer result
5810	R1-R3:	function argument word
5811	R9:	platform specific
5812	R10:	stack limit (used only if stack checking is enabled)
5813	R11:	argument (frame) pointer
5814	R12:	temporary workspace
5815	R13:	stack pointer
5816	R14:	link register
5817	R15:	program counter
5818
5819    ==> U-Boot will use R9 to hold a pointer to the global data
5820
5821    Note: on ARM, only R_ARM_RELATIVE relocations are supported.
5822
5823On Nios II, the ABI is documented here:
5824	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
5825
5826    ==> U-Boot will use gp to hold a pointer to the global data
5827
5828    Note: on Nios II, we give "-G0" option to gcc and don't use gp
5829    to access small data sections, so gp is free.
5830
5831On NDS32, the following registers are used:
5832
5833	R0-R1:	argument/return
5834	R2-R5:	argument
5835	R15:	temporary register for assembler
5836	R16:	trampoline register
5837	R28:	frame pointer (FP)
5838	R29:	global pointer (GP)
5839	R30:	link register (LP)
5840	R31:	stack pointer (SP)
5841	PC:	program counter (PC)
5842
5843    ==> U-Boot will use R10 to hold a pointer to the global data
5844
5845NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
5846or current versions of GCC may "optimize" the code too much.
5847
5848Memory Management:
5849------------------
5850
5851U-Boot runs in system state and uses physical addresses, i.e. the
5852MMU is not used either for address mapping nor for memory protection.
5853
5854The available memory is mapped to fixed addresses using the memory
5855controller. In this process, a contiguous block is formed for each
5856memory type (Flash, SDRAM, SRAM), even when it consists of several
5857physical memory banks.
5858
5859U-Boot is installed in the first 128 kB of the first Flash bank (on
5860TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
5861booting and sizing and initializing DRAM, the code relocates itself
5862to the upper end of DRAM. Immediately below the U-Boot code some
5863memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
5864configuration setting]. Below that, a structure with global Board
5865Info data is placed, followed by the stack (growing downward).
5866
5867Additionally, some exception handler code is copied to the low 8 kB
5868of DRAM (0x00000000 ... 0x00001FFF).
5869
5870So a typical memory configuration with 16 MB of DRAM could look like
5871this:
5872
5873	0x0000 0000	Exception Vector code
5874	      :
5875	0x0000 1FFF
5876	0x0000 2000	Free for Application Use
5877	      :
5878	      :
5879
5880	      :
5881	      :
5882	0x00FB FF20	Monitor Stack (Growing downward)
5883	0x00FB FFAC	Board Info Data and permanent copy of global data
5884	0x00FC 0000	Malloc Arena
5885	      :
5886	0x00FD FFFF
5887	0x00FE 0000	RAM Copy of Monitor Code
5888	...		eventually: LCD or video framebuffer
5889	...		eventually: pRAM (Protected RAM - unchanged by reset)
5890	0x00FF FFFF	[End of RAM]
5891
5892
5893System Initialization:
5894----------------------
5895
5896In the reset configuration, U-Boot starts at the reset entry point
5897(on most PowerPC systems at address 0x00000100). Because of the reset
5898configuration for CS0# this is a mirror of the onboard Flash memory.
5899To be able to re-map memory U-Boot then jumps to its link address.
5900To be able to implement the initialization code in C, a (small!)
5901initial stack is set up in the internal Dual Ported RAM (in case CPUs
5902which provide such a feature like MPC8xx or MPC8260), or in a locked
5903part of the data cache. After that, U-Boot initializes the CPU core,
5904the caches and the SIU.
5905
5906Next, all (potentially) available memory banks are mapped using a
5907preliminary mapping. For example, we put them on 512 MB boundaries
5908(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
5909on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
5910programmed for SDRAM access. Using the temporary configuration, a
5911simple memory test is run that determines the size of the SDRAM
5912banks.
5913
5914When there is more than one SDRAM bank, and the banks are of
5915different size, the largest is mapped first. For equal size, the first
5916bank (CS2#) is mapped first. The first mapping is always for address
59170x00000000, with any additional banks following immediately to create
5918contiguous memory starting from 0.
5919
5920Then, the monitor installs itself at the upper end of the SDRAM area
5921and allocates memory for use by malloc() and for the global Board
5922Info data; also, the exception vector code is copied to the low RAM
5923pages, and the final stack is set up.
5924
5925Only after this relocation will you have a "normal" C environment;
5926until that you are restricted in several ways, mostly because you are
5927running from ROM, and because the code will have to be relocated to a
5928new address in RAM.
5929
5930
5931U-Boot Porting Guide:
5932----------------------
5933
5934[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
5935list, October 2002]
5936
5937
5938int main(int argc, char *argv[])
5939{
5940	sighandler_t no_more_time;
5941
5942	signal(SIGALRM, no_more_time);
5943	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
5944
5945	if (available_money > available_manpower) {
5946		Pay consultant to port U-Boot;
5947		return 0;
5948	}
5949
5950	Download latest U-Boot source;
5951
5952	Subscribe to u-boot mailing list;
5953
5954	if (clueless)
5955		email("Hi, I am new to U-Boot, how do I get started?");
5956
5957	while (learning) {
5958		Read the README file in the top level directory;
5959		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
5960		Read applicable doc/*.README;
5961		Read the source, Luke;
5962		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
5963	}
5964
5965	if (available_money > toLocalCurrency ($2500))
5966		Buy a BDI3000;
5967	else
5968		Add a lot of aggravation and time;
5969
5970	if (a similar board exists) {	/* hopefully... */
5971		cp -a board/<similar> board/<myboard>
5972		cp include/configs/<similar>.h include/configs/<myboard>.h
5973	} else {
5974		Create your own board support subdirectory;
5975		Create your own board include/configs/<myboard>.h file;
5976	}
5977	Edit new board/<myboard> files
5978	Edit new include/configs/<myboard>.h
5979
5980	while (!accepted) {
5981		while (!running) {
5982			do {
5983				Add / modify source code;
5984			} until (compiles);
5985			Debug;
5986			if (clueless)
5987				email("Hi, I am having problems...");
5988		}
5989		Send patch file to the U-Boot email list;
5990		if (reasonable critiques)
5991			Incorporate improvements from email list code review;
5992		else
5993			Defend code as written;
5994	}
5995
5996	return 0;
5997}
5998
5999void no_more_time (int sig)
6000{
6001      hire_a_guru();
6002}
6003
6004
6005Coding Standards:
6006-----------------
6007
6008All contributions to U-Boot should conform to the Linux kernel
6009coding style; see the file "Documentation/CodingStyle" and the script
6010"scripts/Lindent" in your Linux kernel source directory.
6011
6012Source files originating from a different project (for example the
6013MTD subsystem) are generally exempt from these guidelines and are not
6014reformated to ease subsequent migration to newer versions of those
6015sources.
6016
6017Please note that U-Boot is implemented in C (and to some small parts in
6018Assembler); no C++ is used, so please do not use C++ style comments (//)
6019in your code.
6020
6021Please also stick to the following formatting rules:
6022- remove any trailing white space
6023- use TAB characters for indentation and vertical alignment, not spaces
6024- make sure NOT to use DOS '\r\n' line feeds
6025- do not add more than 2 consecutive empty lines to source files
6026- do not add trailing empty lines to source files
6027
6028Submissions which do not conform to the standards may be returned
6029with a request to reformat the changes.
6030
6031
6032Submitting Patches:
6033-------------------
6034
6035Since the number of patches for U-Boot is growing, we need to
6036establish some rules. Submissions which do not conform to these rules
6037may be rejected, even when they contain important and valuable stuff.
6038
6039Please see http://www.denx.de/wiki/U-Boot/Patches for details.
6040
6041Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
6042see http://lists.denx.de/mailman/listinfo/u-boot
6043
6044When you send a patch, please include the following information with
6045it:
6046
6047* For bug fixes: a description of the bug and how your patch fixes
6048  this bug. Please try to include a way of demonstrating that the
6049  patch actually fixes something.
6050
6051* For new features: a description of the feature and your
6052  implementation.
6053
6054* A CHANGELOG entry as plaintext (separate from the patch)
6055
6056* For major contributions, your entry to the CREDITS file
6057
6058* When you add support for a new board, don't forget to add a
6059  maintainer e-mail address to the boards.cfg file, too.
6060
6061* If your patch adds new configuration options, don't forget to
6062  document these in the README file.
6063
6064* The patch itself. If you are using git (which is *strongly*
6065  recommended) you can easily generate the patch using the
6066  "git format-patch". If you then use "git send-email" to send it to
6067  the U-Boot mailing list, you will avoid most of the common problems
6068  with some other mail clients.
6069
6070  If you cannot use git, use "diff -purN OLD NEW". If your version of
6071  diff does not support these options, then get the latest version of
6072  GNU diff.
6073
6074  The current directory when running this command shall be the parent
6075  directory of the U-Boot source tree (i. e. please make sure that
6076  your patch includes sufficient directory information for the
6077  affected files).
6078
6079  We prefer patches as plain text. MIME attachments are discouraged,
6080  and compressed attachments must not be used.
6081
6082* If one logical set of modifications affects or creates several
6083  files, all these changes shall be submitted in a SINGLE patch file.
6084
6085* Changesets that contain different, unrelated modifications shall be
6086  submitted as SEPARATE patches, one patch per changeset.
6087
6088
6089Notes:
6090
6091* Before sending the patch, run the MAKEALL script on your patched
6092  source tree and make sure that no errors or warnings are reported
6093  for any of the boards.
6094
6095* Keep your modifications to the necessary minimum: A patch
6096  containing several unrelated changes or arbitrary reformats will be
6097  returned with a request to re-formatting / split it.
6098
6099* If you modify existing code, make sure that your new code does not
6100  add to the memory footprint of the code ;-) Small is beautiful!
6101  When adding new features, these should compile conditionally only
6102  (using #ifdef), and the resulting code with the new feature
6103  disabled must not need more memory than the old code without your
6104  modification.
6105
6106* Remember that there is a size limit of 100 kB per message on the
6107  u-boot mailing list. Bigger patches will be moderated. If they are
6108  reasonable and not too big, they will be acknowledged. But patches
6109  bigger than the size limit should be avoided.
6110