xref: /rk3399_rockchip-uboot/README (revision 6853e6aa77b388998a5368b400aee3ae7776b1c2)
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- Intel Monahans options:
490		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
491
492		Defines the Monahans run mode to oscillator
493		ratio. Valid values are 8, 16, 24, 31. The core
494		frequency is this value multiplied by 13 MHz.
495
496		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
497
498		Defines the Monahans turbo mode to oscillator
499		ratio. Valid values are 1 (default if undefined) and
500		2. The core frequency as calculated above is multiplied
501		by this value.
502
503- MIPS CPU options:
504		CONFIG_SYS_INIT_SP_OFFSET
505
506		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
507		pointer. This is needed for the temporary stack before
508		relocation.
509
510		CONFIG_SYS_MIPS_CACHE_MODE
511
512		Cache operation mode for the MIPS CPU.
513		See also arch/mips/include/asm/mipsregs.h.
514		Possible values are:
515			CONF_CM_CACHABLE_NO_WA
516			CONF_CM_CACHABLE_WA
517			CONF_CM_UNCACHED
518			CONF_CM_CACHABLE_NONCOHERENT
519			CONF_CM_CACHABLE_CE
520			CONF_CM_CACHABLE_COW
521			CONF_CM_CACHABLE_CUW
522			CONF_CM_CACHABLE_ACCELERATED
523
524		CONFIG_SYS_XWAY_EBU_BOOTCFG
525
526		Special option for Lantiq XWAY SoCs for booting from NOR flash.
527		See also arch/mips/cpu/mips32/start.S.
528
529		CONFIG_XWAY_SWAP_BYTES
530
531		Enable compilation of tools/xway-swap-bytes needed for Lantiq
532		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
533		be swapped if a flash programmer is used.
534
535- ARM options:
536		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
537
538		Select high exception vectors of the ARM core, e.g., do not
539		clear the V bit of the c1 register of CP15.
540
541		CONFIG_SYS_THUMB_BUILD
542
543		Use this flag to build U-Boot using the Thumb instruction
544		set for ARM architectures. Thumb instruction set provides
545		better code density. For ARM architectures that support
546		Thumb2 this flag will result in Thumb2 code generated by
547		GCC.
548
549		CONFIG_ARM_ERRATA_716044
550		CONFIG_ARM_ERRATA_742230
551		CONFIG_ARM_ERRATA_743622
552		CONFIG_ARM_ERRATA_751472
553
554		If set, the workarounds for these ARM errata are applied early
555		during U-Boot startup. Note that these options force the
556		workarounds to be applied; no CPU-type/version detection
557		exists, unlike the similar options in the Linux kernel. Do not
558		set these options unless they apply!
559
560- CPU timer options:
561		CONFIG_SYS_HZ
562
563		The frequency of the timer returned by get_timer().
564		get_timer() must operate in milliseconds and this CONFIG
565		option must be set to 1000.
566
567- Linux Kernel Interface:
568		CONFIG_CLOCKS_IN_MHZ
569
570		U-Boot stores all clock information in Hz
571		internally. For binary compatibility with older Linux
572		kernels (which expect the clocks passed in the
573		bd_info data to be in MHz) the environment variable
574		"clocks_in_mhz" can be defined so that U-Boot
575		converts clock data to MHZ before passing it to the
576		Linux kernel.
577		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
578		"clocks_in_mhz=1" is automatically included in the
579		default environment.
580
581		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
582
583		When transferring memsize parameter to linux, some versions
584		expect it to be in bytes, others in MB.
585		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
586
587		CONFIG_OF_LIBFDT
588
589		New kernel versions are expecting firmware settings to be
590		passed using flattened device trees (based on open firmware
591		concepts).
592
593		CONFIG_OF_LIBFDT
594		 * New libfdt-based support
595		 * Adds the "fdt" command
596		 * The bootm command automatically updates the fdt
597
598		OF_CPU - The proper name of the cpus node (only required for
599			MPC512X and MPC5xxx based boards).
600		OF_SOC - The proper name of the soc node (only required for
601			MPC512X and MPC5xxx based boards).
602		OF_TBCLK - The timebase frequency.
603		OF_STDOUT_PATH - The path to the console device
604
605		boards with QUICC Engines require OF_QE to set UCC MAC
606		addresses
607
608		CONFIG_OF_BOARD_SETUP
609
610		Board code has addition modification that it wants to make
611		to the flat device tree before handing it off to the kernel
612
613		CONFIG_OF_BOOT_CPU
614
615		This define fills in the correct boot CPU in the boot
616		param header, the default value is zero if undefined.
617
618		CONFIG_OF_IDE_FIXUP
619
620		U-Boot can detect if an IDE device is present or not.
621		If not, and this new config option is activated, U-Boot
622		removes the ATA node from the DTS before booting Linux,
623		so the Linux IDE driver does not probe the device and
624		crash. This is needed for buggy hardware (uc101) where
625		no pull down resistor is connected to the signal IDE5V_DD7.
626
627		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
628
629		This setting is mandatory for all boards that have only one
630		machine type and must be used to specify the machine type
631		number as it appears in the ARM machine registry
632		(see http://www.arm.linux.org.uk/developer/machines/).
633		Only boards that have multiple machine types supported
634		in a single configuration file and the machine type is
635		runtime discoverable, do not have to use this setting.
636
637- vxWorks boot parameters:
638
639		bootvx constructs a valid bootline using the following
640		environments variables: bootfile, ipaddr, serverip, hostname.
641		It loads the vxWorks image pointed bootfile.
642
643		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
644		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
645		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
646		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
647
648		CONFIG_SYS_VXWORKS_ADD_PARAMS
649
650		Add it at the end of the bootline. E.g "u=username pw=secret"
651
652		Note: If a "bootargs" environment is defined, it will overwride
653		the defaults discussed just above.
654
655- Cache Configuration:
656		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
657		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
658		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
659
660- Cache Configuration for ARM:
661		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
662				      controller
663		CONFIG_SYS_PL310_BASE - Physical base address of PL310
664					controller register space
665
666- Serial Ports:
667		CONFIG_PL010_SERIAL
668
669		Define this if you want support for Amba PrimeCell PL010 UARTs.
670
671		CONFIG_PL011_SERIAL
672
673		Define this if you want support for Amba PrimeCell PL011 UARTs.
674
675		CONFIG_PL011_CLOCK
676
677		If you have Amba PrimeCell PL011 UARTs, set this variable to
678		the clock speed of the UARTs.
679
680		CONFIG_PL01x_PORTS
681
682		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
683		define this to a list of base addresses for each (supported)
684		port. See e.g. include/configs/versatile.h
685
686		CONFIG_PL011_SERIAL_RLCR
687
688		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
689		have separate receive and transmit line control registers.  Set
690		this variable to initialize the extra register.
691
692		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
693
694		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
695		boot loader that has already initialized the UART.  Define this
696		variable to flush the UART at init time.
697
698
699- Console Interface:
700		Depending on board, define exactly one serial port
701		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
702		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
703		console by defining CONFIG_8xx_CONS_NONE
704
705		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
706		port routines must be defined elsewhere
707		(i.e. serial_init(), serial_getc(), ...)
708
709		CONFIG_CFB_CONSOLE
710		Enables console device for a color framebuffer. Needs following
711		defines (cf. smiLynxEM, i8042)
712			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
713						(default big endian)
714			VIDEO_HW_RECTFILL	graphic chip supports
715						rectangle fill
716						(cf. smiLynxEM)
717			VIDEO_HW_BITBLT		graphic chip supports
718						bit-blit (cf. smiLynxEM)
719			VIDEO_VISIBLE_COLS	visible pixel columns
720						(cols=pitch)
721			VIDEO_VISIBLE_ROWS	visible pixel rows
722			VIDEO_PIXEL_SIZE	bytes per pixel
723			VIDEO_DATA_FORMAT	graphic data format
724						(0-5, cf. cfb_console.c)
725			VIDEO_FB_ADRS		framebuffer address
726			VIDEO_KBD_INIT_FCT	keyboard int fct
727						(i.e. i8042_kbd_init())
728			VIDEO_TSTC_FCT		test char fct
729						(i.e. i8042_tstc)
730			VIDEO_GETC_FCT		get char fct
731						(i.e. i8042_getc)
732			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
733						(requires blink timer
734						cf. i8042.c)
735			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
736			CONFIG_CONSOLE_TIME	display time/date info in
737						upper right corner
738						(requires CONFIG_CMD_DATE)
739			CONFIG_VIDEO_LOGO	display Linux logo in
740						upper left corner
741			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
742						linux_logo.h for logo.
743						Requires CONFIG_VIDEO_LOGO
744			CONFIG_CONSOLE_EXTRA_INFO
745						additional board info beside
746						the logo
747
748		When CONFIG_CFB_CONSOLE_ANSI is defined, console will support
749		a limited number of ANSI escape sequences (cursor control,
750		erase functions and limited graphics rendition control).
751
752		When CONFIG_CFB_CONSOLE is defined, video console is
753		default i/o. Serial console can be forced with
754		environment 'console=serial'.
755
756		When CONFIG_SILENT_CONSOLE is defined, all console
757		messages (by U-Boot and Linux!) can be silenced with
758		the "silent" environment variable. See
759		doc/README.silent for more information.
760
761		CONFIG_SYS_CONSOLE_BG_COL: define the backgroundcolor, default
762			is 0x00.
763		CONFIG_SYS_CONSOLE_FG_COL: define the foregroundcolor, default
764			is 0xa0.
765
766- Console Baudrate:
767		CONFIG_BAUDRATE - in bps
768		Select one of the baudrates listed in
769		CONFIG_SYS_BAUDRATE_TABLE, see below.
770		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
771
772- Console Rx buffer length
773		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
774		the maximum receive buffer length for the SMC.
775		This option is actual only for 82xx and 8xx possible.
776		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
777		must be defined, to setup the maximum idle timeout for
778		the SMC.
779
780- Pre-Console Buffer:
781		Prior to the console being initialised (i.e. serial UART
782		initialised etc) all console output is silently discarded.
783		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
784		buffer any console messages prior to the console being
785		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
786		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
787		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
788		bytes are output before the console is initialised, the
789		earlier bytes are discarded.
790
791		'Sane' compilers will generate smaller code if
792		CONFIG_PRE_CON_BUF_SZ is a power of 2
793
794- Safe printf() functions
795		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
796		the printf() functions. These are defined in
797		include/vsprintf.h and include snprintf(), vsnprintf() and
798		so on. Code size increase is approximately 300-500 bytes.
799		If this option is not given then these functions will
800		silently discard their buffer size argument - this means
801		you are not getting any overflow checking in this case.
802
803- Boot Delay:	CONFIG_BOOTDELAY - in seconds
804		Delay before automatically booting the default image;
805		set to -1 to disable autoboot.
806		set to -2 to autoboot with no delay and not check for abort
807		(even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).
808
809		See doc/README.autoboot for these options that
810		work with CONFIG_BOOTDELAY. None are required.
811		CONFIG_BOOT_RETRY_TIME
812		CONFIG_BOOT_RETRY_MIN
813		CONFIG_AUTOBOOT_KEYED
814		CONFIG_AUTOBOOT_PROMPT
815		CONFIG_AUTOBOOT_DELAY_STR
816		CONFIG_AUTOBOOT_STOP_STR
817		CONFIG_AUTOBOOT_DELAY_STR2
818		CONFIG_AUTOBOOT_STOP_STR2
819		CONFIG_ZERO_BOOTDELAY_CHECK
820		CONFIG_RESET_TO_RETRY
821
822- Autoboot Command:
823		CONFIG_BOOTCOMMAND
824		Only needed when CONFIG_BOOTDELAY is enabled;
825		define a command string that is automatically executed
826		when no character is read on the console interface
827		within "Boot Delay" after reset.
828
829		CONFIG_BOOTARGS
830		This can be used to pass arguments to the bootm
831		command. The value of CONFIG_BOOTARGS goes into the
832		environment value "bootargs".
833
834		CONFIG_RAMBOOT and CONFIG_NFSBOOT
835		The value of these goes into the environment as
836		"ramboot" and "nfsboot" respectively, and can be used
837		as a convenience, when switching between booting from
838		RAM and NFS.
839
840- Bootcount:
841		CONFIG_BOOTCOUNT_LIMIT
842		Implements a mechanism for detecting a repeating reboot
843		cycle, see:
844		http://www.denx.de/wiki/view/DULG/UBootBootCountLimit
845
846		CONFIG_BOOTCOUNT_ENV
847		If no softreset save registers are found on the hardware
848		"bootcount" is stored in the environment. To prevent a
849		saveenv on all reboots, the environment variable
850		"upgrade_available" is used. If "upgrade_available" is
851		0, "bootcount" is always 0, if "upgrade_available" is
852		1 "bootcount" is incremented in the environment.
853		So the Userspace Applikation must set the "upgrade_available"
854		and "bootcount" variable to 0, if a boot was successfully.
855
856- Pre-Boot Commands:
857		CONFIG_PREBOOT
858
859		When this option is #defined, the existence of the
860		environment variable "preboot" will be checked
861		immediately before starting the CONFIG_BOOTDELAY
862		countdown and/or running the auto-boot command resp.
863		entering interactive mode.
864
865		This feature is especially useful when "preboot" is
866		automatically generated or modified. For an example
867		see the LWMON board specific code: here "preboot" is
868		modified when the user holds down a certain
869		combination of keys on the (special) keyboard when
870		booting the systems
871
872- Serial Download Echo Mode:
873		CONFIG_LOADS_ECHO
874		If defined to 1, all characters received during a
875		serial download (using the "loads" command) are
876		echoed back. This might be needed by some terminal
877		emulations (like "cu"), but may as well just take
878		time on others. This setting #define's the initial
879		value of the "loads_echo" environment variable.
880
881- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
882		CONFIG_KGDB_BAUDRATE
883		Select one of the baudrates listed in
884		CONFIG_SYS_BAUDRATE_TABLE, see below.
885
886- Monitor Functions:
887		Monitor commands can be included or excluded
888		from the build by using the #include files
889		<config_cmd_all.h> and #undef'ing unwanted
890		commands, or using <config_cmd_default.h>
891		and augmenting with additional #define's
892		for wanted commands.
893
894		The default command configuration includes all commands
895		except those marked below with a "*".
896
897		CONFIG_CMD_ASKENV	* ask for env variable
898		CONFIG_CMD_BDI		  bdinfo
899		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
900		CONFIG_CMD_BMP		* BMP support
901		CONFIG_CMD_BSP		* Board specific commands
902		CONFIG_CMD_BOOTD	  bootd
903		CONFIG_CMD_CACHE	* icache, dcache
904		CONFIG_CMD_CLK   	* clock command support
905		CONFIG_CMD_CONSOLE	  coninfo
906		CONFIG_CMD_CRC32	* crc32
907		CONFIG_CMD_DATE		* support for RTC, date/time...
908		CONFIG_CMD_DHCP		* DHCP support
909		CONFIG_CMD_DIAG		* Diagnostics
910		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
911		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
912		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
913		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
914		CONFIG_CMD_DTT		* Digital Therm and Thermostat
915		CONFIG_CMD_ECHO		  echo arguments
916		CONFIG_CMD_EDITENV	  edit env variable
917		CONFIG_CMD_EEPROM	* EEPROM read/write support
918		CONFIG_CMD_ELF		* bootelf, bootvx
919		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
920		CONFIG_CMD_ENV_FLAGS	* display details about env flags
921		CONFIG_CMD_ENV_EXISTS	* check existence of env variable
922		CONFIG_CMD_EXPORTENV	* export the environment
923		CONFIG_CMD_EXT2		* ext2 command support
924		CONFIG_CMD_EXT4		* ext4 command support
925		CONFIG_CMD_FS_GENERIC	* filesystem commands (e.g. load, ls)
926					  that work for multiple fs types
927		CONFIG_CMD_SAVEENV	  saveenv
928		CONFIG_CMD_FDC		* Floppy Disk Support
929		CONFIG_CMD_FAT		* FAT command support
930		CONFIG_CMD_FDOS		* Dos diskette Support
931		CONFIG_CMD_FLASH	  flinfo, erase, protect
932		CONFIG_CMD_FPGA		  FPGA device initialization support
933		CONFIG_CMD_FUSE		* Device fuse support
934		CONFIG_CMD_GETTIME	* Get time since boot
935		CONFIG_CMD_GO		* the 'go' command (exec code)
936		CONFIG_CMD_GREPENV	* search environment
937		CONFIG_CMD_HASH		* calculate hash / digest
938		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
939		CONFIG_CMD_I2C		* I2C serial bus support
940		CONFIG_CMD_IDE		* IDE harddisk support
941		CONFIG_CMD_IMI		  iminfo
942		CONFIG_CMD_IMLS		  List all images found in NOR flash
943		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash
944		CONFIG_CMD_IMMAP	* IMMR dump support
945		CONFIG_CMD_IMPORTENV	* import an environment
946		CONFIG_CMD_INI		* import data from an ini file into the env
947		CONFIG_CMD_IRQ		* irqinfo
948		CONFIG_CMD_ITEST	  Integer/string test of 2 values
949		CONFIG_CMD_JFFS2	* JFFS2 Support
950		CONFIG_CMD_KGDB		* kgdb
951		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)
952		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
953					  (169.254.*.*)
954		CONFIG_CMD_LOADB	  loadb
955		CONFIG_CMD_LOADS	  loads
956		CONFIG_CMD_MD5SUM	* print md5 message digest
957					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
958		CONFIG_CMD_MEMINFO	* Display detailed memory information
959		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
960					  loop, loopw
961		CONFIG_CMD_MEMTEST	* mtest
962		CONFIG_CMD_MISC		  Misc functions like sleep etc
963		CONFIG_CMD_MMC		* MMC memory mapped support
964		CONFIG_CMD_MII		* MII utility commands
965		CONFIG_CMD_MTDPARTS	* MTD partition support
966		CONFIG_CMD_NAND		* NAND support
967		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
968		CONFIG_CMD_NFS		  NFS support
969		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
970		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
971		CONFIG_CMD_PCI		* pciinfo
972		CONFIG_CMD_PCMCIA		* PCMCIA support
973		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
974					  host
975		CONFIG_CMD_PORTIO	* Port I/O
976		CONFIG_CMD_READ		* Read raw data from partition
977		CONFIG_CMD_REGINFO	* Register dump
978		CONFIG_CMD_RUN		  run command in env variable
979		CONFIG_CMD_SANDBOX	* sb command to access sandbox features
980		CONFIG_CMD_SAVES	* save S record dump
981		CONFIG_CMD_SCSI		* SCSI Support
982		CONFIG_CMD_SDRAM	* print SDRAM configuration information
983					  (requires CONFIG_CMD_I2C)
984		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
985					  (4xx only)
986		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
987		CONFIG_CMD_SHA1SUM	* print sha1 memory digest
988					  (requires CONFIG_CMD_MEMORY)
989		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x
990		CONFIG_CMD_SOURCE	  "source" command Support
991		CONFIG_CMD_SPI		* SPI serial bus support
992		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
993		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
994		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
995		CONFIG_CMD_TIMER	* access to the system tick timer
996		CONFIG_CMD_USB		* USB support
997		CONFIG_CMD_CDP		* Cisco Discover Protocol support
998		CONFIG_CMD_MFSL		* Microblaze FSL support
999		CONFIG_CMD_XIMG		  Load part of Multi Image
1000
1001
1002		EXAMPLE: If you want all functions except of network
1003		support you can write:
1004
1005		#include "config_cmd_all.h"
1006		#undef CONFIG_CMD_NET
1007
1008	Other Commands:
1009		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
1010
1011	Note:	Don't enable the "icache" and "dcache" commands
1012		(configuration option CONFIG_CMD_CACHE) unless you know
1013		what you (and your U-Boot users) are doing. Data
1014		cache cannot be enabled on systems like the 8xx or
1015		8260 (where accesses to the IMMR region must be
1016		uncached), and it cannot be disabled on all other
1017		systems where we (mis-) use the data cache to hold an
1018		initial stack and some data.
1019
1020
1021		XXX - this list needs to get updated!
1022
1023- Regular expression support:
1024		CONFIG_REGEX
1025		If this variable is defined, U-Boot is linked against
1026		the SLRE (Super Light Regular Expression) library,
1027		which adds regex support to some commands, as for
1028		example "env grep" and "setexpr".
1029
1030- Device tree:
1031		CONFIG_OF_CONTROL
1032		If this variable is defined, U-Boot will use a device tree
1033		to configure its devices, instead of relying on statically
1034		compiled #defines in the board file. This option is
1035		experimental and only available on a few boards. The device
1036		tree is available in the global data as gd->fdt_blob.
1037
1038		U-Boot needs to get its device tree from somewhere. This can
1039		be done using one of the two options below:
1040
1041		CONFIG_OF_EMBED
1042		If this variable is defined, U-Boot will embed a device tree
1043		binary in its image. This device tree file should be in the
1044		board directory and called <soc>-<board>.dts. The binary file
1045		is then picked up in board_init_f() and made available through
1046		the global data structure as gd->blob.
1047
1048		CONFIG_OF_SEPARATE
1049		If this variable is defined, U-Boot will build a device tree
1050		binary. It will be called u-boot.dtb. Architecture-specific
1051		code will locate it at run-time. Generally this works by:
1052
1053			cat u-boot.bin u-boot.dtb >image.bin
1054
1055		and in fact, U-Boot does this for you, creating a file called
1056		u-boot-dtb.bin which is useful in the common case. You can
1057		still use the individual files if you need something more
1058		exotic.
1059
1060- Watchdog:
1061		CONFIG_WATCHDOG
1062		If this variable is defined, it enables watchdog
1063		support for the SoC. There must be support in the SoC
1064		specific code for a watchdog. For the 8xx and 8260
1065		CPUs, the SIU Watchdog feature is enabled in the SYPCR
1066		register.  When supported for a specific SoC is
1067		available, then no further board specific code should
1068		be needed to use it.
1069
1070		CONFIG_HW_WATCHDOG
1071		When using a watchdog circuitry external to the used
1072		SoC, then define this variable and provide board
1073		specific code for the "hw_watchdog_reset" function.
1074
1075- U-Boot Version:
1076		CONFIG_VERSION_VARIABLE
1077		If this variable is defined, an environment variable
1078		named "ver" is created by U-Boot showing the U-Boot
1079		version as printed by the "version" command.
1080		Any change to this variable will be reverted at the
1081		next reset.
1082
1083- Real-Time Clock:
1084
1085		When CONFIG_CMD_DATE is selected, the type of the RTC
1086		has to be selected, too. Define exactly one of the
1087		following options:
1088
1089		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
1090		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
1091		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
1092		CONFIG_RTC_MC146818	- use MC146818 RTC
1093		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
1094		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
1095		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
1096		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
1097		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
1098		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
1099		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
1100		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
1101					  RV3029 RTC.
1102
1103		Note that if the RTC uses I2C, then the I2C interface
1104		must also be configured. See I2C Support, below.
1105
1106- GPIO Support:
1107		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
1108
1109		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1110		chip-ngpio pairs that tell the PCA953X driver the number of
1111		pins supported by a particular chip.
1112
1113		Note that if the GPIO device uses I2C, then the I2C interface
1114		must also be configured. See I2C Support, below.
1115
1116- Timestamp Support:
1117
1118		When CONFIG_TIMESTAMP is selected, the timestamp
1119		(date and time) of an image is printed by image
1120		commands like bootm or iminfo. This option is
1121		automatically enabled when you select CONFIG_CMD_DATE .
1122
1123- Partition Labels (disklabels) Supported:
1124		Zero or more of the following:
1125		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1126		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1127				       Intel architecture, USB sticks, etc.
1128		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1129		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1130				       bootloader.  Note 2TB partition limit; see
1131				       disk/part_efi.c
1132		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1133
1134		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1135		CONFIG_CMD_SCSI) you must configure support for at
1136		least one non-MTD partition type as well.
1137
1138- IDE Reset method:
1139		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1140		board configurations files but used nowhere!
1141
1142		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1143		be performed by calling the function
1144			ide_set_reset(int reset)
1145		which has to be defined in a board specific file
1146
1147- ATAPI Support:
1148		CONFIG_ATAPI
1149
1150		Set this to enable ATAPI support.
1151
1152- LBA48 Support
1153		CONFIG_LBA48
1154
1155		Set this to enable support for disks larger than 137GB
1156		Also look at CONFIG_SYS_64BIT_LBA.
1157		Whithout these , LBA48 support uses 32bit variables and will 'only'
1158		support disks up to 2.1TB.
1159
1160		CONFIG_SYS_64BIT_LBA:
1161			When enabled, makes the IDE subsystem use 64bit sector addresses.
1162			Default is 32bit.
1163
1164- SCSI Support:
1165		At the moment only there is only support for the
1166		SYM53C8XX SCSI controller; define
1167		CONFIG_SCSI_SYM53C8XX to enable it.
1168
1169		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1170		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1171		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1172		maximum numbers of LUNs, SCSI ID's and target
1173		devices.
1174		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1175
1176		The environment variable 'scsidevs' is set to the number of
1177		SCSI devices found during the last scan.
1178
1179- NETWORK Support (PCI):
1180		CONFIG_E1000
1181		Support for Intel 8254x/8257x gigabit chips.
1182
1183		CONFIG_E1000_SPI
1184		Utility code for direct access to the SPI bus on Intel 8257x.
1185		This does not do anything useful unless you set at least one
1186		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1187
1188		CONFIG_E1000_SPI_GENERIC
1189		Allow generic access to the SPI bus on the Intel 8257x, for
1190		example with the "sspi" command.
1191
1192		CONFIG_CMD_E1000
1193		Management command for E1000 devices.  When used on devices
1194		with SPI support you can reprogram the EEPROM from U-Boot.
1195
1196		CONFIG_E1000_FALLBACK_MAC
1197		default MAC for empty EEPROM after production.
1198
1199		CONFIG_EEPRO100
1200		Support for Intel 82557/82559/82559ER chips.
1201		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1202		write routine for first time initialisation.
1203
1204		CONFIG_TULIP
1205		Support for Digital 2114x chips.
1206		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1207		modem chip initialisation (KS8761/QS6611).
1208
1209		CONFIG_NATSEMI
1210		Support for National dp83815 chips.
1211
1212		CONFIG_NS8382X
1213		Support for National dp8382[01] gigabit chips.
1214
1215- NETWORK Support (other):
1216
1217		CONFIG_DRIVER_AT91EMAC
1218		Support for AT91RM9200 EMAC.
1219
1220			CONFIG_RMII
1221			Define this to use reduced MII inteface
1222
1223			CONFIG_DRIVER_AT91EMAC_QUIET
1224			If this defined, the driver is quiet.
1225			The driver doen't show link status messages.
1226
1227		CONFIG_CALXEDA_XGMAC
1228		Support for the Calxeda XGMAC device
1229
1230		CONFIG_LAN91C96
1231		Support for SMSC's LAN91C96 chips.
1232
1233			CONFIG_LAN91C96_BASE
1234			Define this to hold the physical address
1235			of the LAN91C96's I/O space
1236
1237			CONFIG_LAN91C96_USE_32_BIT
1238			Define this to enable 32 bit addressing
1239
1240		CONFIG_SMC91111
1241		Support for SMSC's LAN91C111 chip
1242
1243			CONFIG_SMC91111_BASE
1244			Define this to hold the physical address
1245			of the device (I/O space)
1246
1247			CONFIG_SMC_USE_32_BIT
1248			Define this if data bus is 32 bits
1249
1250			CONFIG_SMC_USE_IOFUNCS
1251			Define this to use i/o functions instead of macros
1252			(some hardware wont work with macros)
1253
1254		CONFIG_DRIVER_TI_EMAC
1255		Support for davinci emac
1256
1257			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1258			Define this if you have more then 3 PHYs.
1259
1260		CONFIG_FTGMAC100
1261		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1262
1263			CONFIG_FTGMAC100_EGIGA
1264			Define this to use GE link update with gigabit PHY.
1265			Define this if FTGMAC100 is connected to gigabit PHY.
1266			If your system has 10/100 PHY only, it might not occur
1267			wrong behavior. Because PHY usually return timeout or
1268			useless data when polling gigabit status and gigabit
1269			control registers. This behavior won't affect the
1270			correctnessof 10/100 link speed update.
1271
1272		CONFIG_SMC911X
1273		Support for SMSC's LAN911x and LAN921x chips
1274
1275			CONFIG_SMC911X_BASE
1276			Define this to hold the physical address
1277			of the device (I/O space)
1278
1279			CONFIG_SMC911X_32_BIT
1280			Define this if data bus is 32 bits
1281
1282			CONFIG_SMC911X_16_BIT
1283			Define this if data bus is 16 bits. If your processor
1284			automatically converts one 32 bit word to two 16 bit
1285			words you may also try CONFIG_SMC911X_32_BIT.
1286
1287		CONFIG_SH_ETHER
1288		Support for Renesas on-chip Ethernet controller
1289
1290			CONFIG_SH_ETHER_USE_PORT
1291			Define the number of ports to be used
1292
1293			CONFIG_SH_ETHER_PHY_ADDR
1294			Define the ETH PHY's address
1295
1296			CONFIG_SH_ETHER_CACHE_WRITEBACK
1297			If this option is set, the driver enables cache flush.
1298
1299- TPM Support:
1300		CONFIG_TPM
1301		Support TPM devices.
1302
1303		CONFIG_TPM_TIS_I2C
1304		Support for i2c bus TPM devices. Only one device
1305		per system is supported at this time.
1306
1307			CONFIG_TPM_TIS_I2C_BUS_NUMBER
1308			Define the the i2c bus number for the TPM device
1309
1310			CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS
1311			Define the TPM's address on the i2c bus
1312
1313			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1314			Define the burst count bytes upper limit
1315
1316		CONFIG_TPM_ATMEL_TWI
1317		Support for Atmel TWI TPM device. Requires I2C support.
1318
1319		CONFIG_TPM_TIS_LPC
1320		Support for generic parallel port TPM devices. Only one device
1321		per system is supported at this time.
1322
1323			CONFIG_TPM_TIS_BASE_ADDRESS
1324			Base address where the generic TPM device is mapped
1325			to. Contemporary x86 systems usually map it at
1326			0xfed40000.
1327
1328		CONFIG_CMD_TPM
1329		Add tpm monitor functions.
1330		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1331		provides monitor access to authorized functions.
1332
1333		CONFIG_TPM
1334		Define this to enable the TPM support library which provides
1335		functional interfaces to some TPM commands.
1336		Requires support for a TPM device.
1337
1338		CONFIG_TPM_AUTH_SESSIONS
1339		Define this to enable authorized functions in the TPM library.
1340		Requires CONFIG_TPM and CONFIG_SHA1.
1341
1342- USB Support:
1343		At the moment only the UHCI host controller is
1344		supported (PIP405, MIP405, MPC5200); define
1345		CONFIG_USB_UHCI to enable it.
1346		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1347		and define CONFIG_USB_STORAGE to enable the USB
1348		storage devices.
1349		Note:
1350		Supported are USB Keyboards and USB Floppy drives
1351		(TEAC FD-05PUB).
1352		MPC5200 USB requires additional defines:
1353			CONFIG_USB_CLOCK
1354				for 528 MHz Clock: 0x0001bbbb
1355			CONFIG_PSC3_USB
1356				for USB on PSC3
1357			CONFIG_USB_CONFIG
1358				for differential drivers: 0x00001000
1359				for single ended drivers: 0x00005000
1360				for differential drivers on PSC3: 0x00000100
1361				for single ended drivers on PSC3: 0x00004100
1362			CONFIG_SYS_USB_EVENT_POLL
1363				May be defined to allow interrupt polling
1364				instead of using asynchronous interrupts
1365
1366		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1367		txfilltuning field in the EHCI controller on reset.
1368
1369		CONFIG_USB_HUB_MIN_POWER_ON_DELAY defines the minimum
1370		interval for usb hub power-on delay.(minimum 100msec)
1371
1372- USB Device:
1373		Define the below if you wish to use the USB console.
1374		Once firmware is rebuilt from a serial console issue the
1375		command "setenv stdin usbtty; setenv stdout usbtty" and
1376		attach your USB cable. The Unix command "dmesg" should print
1377		it has found a new device. The environment variable usbtty
1378		can be set to gserial or cdc_acm to enable your device to
1379		appear to a USB host as a Linux gserial device or a
1380		Common Device Class Abstract Control Model serial device.
1381		If you select usbtty = gserial you should be able to enumerate
1382		a Linux host by
1383		# modprobe usbserial vendor=0xVendorID product=0xProductID
1384		else if using cdc_acm, simply setting the environment
1385		variable usbtty to be cdc_acm should suffice. The following
1386		might be defined in YourBoardName.h
1387
1388			CONFIG_USB_DEVICE
1389			Define this to build a UDC device
1390
1391			CONFIG_USB_TTY
1392			Define this to have a tty type of device available to
1393			talk to the UDC device
1394
1395			CONFIG_USBD_HS
1396			Define this to enable the high speed support for usb
1397			device and usbtty. If this feature is enabled, a routine
1398			int is_usbd_high_speed(void)
1399			also needs to be defined by the driver to dynamically poll
1400			whether the enumeration has succeded at high speed or full
1401			speed.
1402
1403			CONFIG_SYS_CONSOLE_IS_IN_ENV
1404			Define this if you want stdin, stdout &/or stderr to
1405			be set to usbtty.
1406
1407			mpc8xx:
1408				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1409				Derive USB clock from external clock "blah"
1410				- CONFIG_SYS_USB_EXTC_CLK 0x02
1411
1412				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1413				Derive USB clock from brgclk
1414				- CONFIG_SYS_USB_BRG_CLK 0x04
1415
1416		If you have a USB-IF assigned VendorID then you may wish to
1417		define your own vendor specific values either in BoardName.h
1418		or directly in usbd_vendor_info.h. If you don't define
1419		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1420		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1421		should pretend to be a Linux device to it's target host.
1422
1423			CONFIG_USBD_MANUFACTURER
1424			Define this string as the name of your company for
1425			- CONFIG_USBD_MANUFACTURER "my company"
1426
1427			CONFIG_USBD_PRODUCT_NAME
1428			Define this string as the name of your product
1429			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1430
1431			CONFIG_USBD_VENDORID
1432			Define this as your assigned Vendor ID from the USB
1433			Implementors Forum. This *must* be a genuine Vendor ID
1434			to avoid polluting the USB namespace.
1435			- CONFIG_USBD_VENDORID 0xFFFF
1436
1437			CONFIG_USBD_PRODUCTID
1438			Define this as the unique Product ID
1439			for your device
1440			- CONFIG_USBD_PRODUCTID 0xFFFF
1441
1442		Some USB device drivers may need to check USB cable attachment.
1443		In this case you can enable following config in BoardName.h:
1444			CONFIG_USB_CABLE_CHECK
1445			This enables function definition:
1446			- usb_cable_connected() in include/usb.h
1447			Implementation of this function is board-specific.
1448
1449- ULPI Layer Support:
1450		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1451		the generic ULPI layer. The generic layer accesses the ULPI PHY
1452		via the platform viewport, so you need both the genric layer and
1453		the viewport enabled. Currently only Chipidea/ARC based
1454		viewport is supported.
1455		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1456		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1457		If your ULPI phy needs a different reference clock than the
1458		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1459		the appropriate value in Hz.
1460
1461- MMC Support:
1462		The MMC controller on the Intel PXA is supported. To
1463		enable this define CONFIG_MMC. The MMC can be
1464		accessed from the boot prompt by mapping the device
1465		to physical memory similar to flash. Command line is
1466		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1467		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1468
1469		CONFIG_SH_MMCIF
1470		Support for Renesas on-chip MMCIF controller
1471
1472			CONFIG_SH_MMCIF_ADDR
1473			Define the base address of MMCIF registers
1474
1475			CONFIG_SH_MMCIF_CLK
1476			Define the clock frequency for MMCIF
1477
1478- USB Device Firmware Update (DFU) class support:
1479		CONFIG_DFU_FUNCTION
1480		This enables the USB portion of the DFU USB class
1481
1482		CONFIG_CMD_DFU
1483		This enables the command "dfu" which is used to have
1484		U-Boot create a DFU class device via USB.  This command
1485		requires that the "dfu_alt_info" environment variable be
1486		set and define the alt settings to expose to the host.
1487
1488		CONFIG_DFU_MMC
1489		This enables support for exposing (e)MMC devices via DFU.
1490
1491		CONFIG_DFU_NAND
1492		This enables support for exposing NAND devices via DFU.
1493
1494		CONFIG_DFU_RAM
1495		This enables support for exposing RAM via DFU.
1496		Note: DFU spec refer to non-volatile memory usage, but
1497		allow usages beyond the scope of spec - here RAM usage,
1498		one that would help mostly the developer.
1499
1500		CONFIG_SYS_DFU_DATA_BUF_SIZE
1501		Dfu transfer uses a buffer before writing data to the
1502		raw storage device. Make the size (in bytes) of this buffer
1503		configurable. The size of this buffer is also configurable
1504		through the "dfu_bufsiz" environment variable.
1505
1506		CONFIG_SYS_DFU_MAX_FILE_SIZE
1507		When updating files rather than the raw storage device,
1508		we use a static buffer to copy the file into and then write
1509		the buffer once we've been given the whole file.  Define
1510		this to the maximum filesize (in bytes) for the buffer.
1511		Default is 4 MiB if undefined.
1512
1513- Journaling Flash filesystem support:
1514		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1515		CONFIG_JFFS2_NAND_DEV
1516		Define these for a default partition on a NAND device
1517
1518		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1519		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1520		Define these for a default partition on a NOR device
1521
1522		CONFIG_SYS_JFFS_CUSTOM_PART
1523		Define this to create an own partition. You have to provide a
1524		function struct part_info* jffs2_part_info(int part_num)
1525
1526		If you define only one JFFS2 partition you may also want to
1527		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1528		to disable the command chpart. This is the default when you
1529		have not defined a custom partition
1530
1531- FAT(File Allocation Table) filesystem write function support:
1532		CONFIG_FAT_WRITE
1533
1534		Define this to enable support for saving memory data as a
1535		file in FAT formatted partition.
1536
1537		This will also enable the command "fatwrite" enabling the
1538		user to write files to FAT.
1539
1540CBFS (Coreboot Filesystem) support
1541		CONFIG_CMD_CBFS
1542
1543		Define this to enable support for reading from a Coreboot
1544		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1545		and cbfsload.
1546
1547- Keyboard Support:
1548		CONFIG_ISA_KEYBOARD
1549
1550		Define this to enable standard (PC-Style) keyboard
1551		support
1552
1553		CONFIG_I8042_KBD
1554		Standard PC keyboard driver with US (is default) and
1555		GERMAN key layout (switch via environment 'keymap=de') support.
1556		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1557		for cfb_console. Supports cursor blinking.
1558
1559		CONFIG_CROS_EC_KEYB
1560		Enables a Chrome OS keyboard using the CROS_EC interface.
1561		This uses CROS_EC to communicate with a second microcontroller
1562		which provides key scans on request.
1563
1564- Video support:
1565		CONFIG_VIDEO
1566
1567		Define this to enable video support (for output to
1568		video).
1569
1570		CONFIG_VIDEO_CT69000
1571
1572		Enable Chips & Technologies 69000 Video chip
1573
1574		CONFIG_VIDEO_SMI_LYNXEM
1575		Enable Silicon Motion SMI 712/710/810 Video chip. The
1576		video output is selected via environment 'videoout'
1577		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1578		assumed.
1579
1580		For the CT69000 and SMI_LYNXEM drivers, videomode is
1581		selected via environment 'videomode'. Two different ways
1582		are possible:
1583		- "videomode=num"   'num' is a standard LiLo mode numbers.
1584		Following standard modes are supported	(* is default):
1585
1586		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1587		-------------+---------------------------------------------
1588		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1589		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1590		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1591		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1592		-------------+---------------------------------------------
1593		(i.e. setenv videomode 317; saveenv; reset;)
1594
1595		- "videomode=bootargs" all the video parameters are parsed
1596		from the bootargs. (See drivers/video/videomodes.c)
1597
1598
1599		CONFIG_VIDEO_SED13806
1600		Enable Epson SED13806 driver. This driver supports 8bpp
1601		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1602		or CONFIG_VIDEO_SED13806_16BPP
1603
1604		CONFIG_FSL_DIU_FB
1605		Enable the Freescale DIU video driver.	Reference boards for
1606		SOCs that have a DIU should define this macro to enable DIU
1607		support, and should also define these other macros:
1608
1609			CONFIG_SYS_DIU_ADDR
1610			CONFIG_VIDEO
1611			CONFIG_CMD_BMP
1612			CONFIG_CFB_CONSOLE
1613			CONFIG_VIDEO_SW_CURSOR
1614			CONFIG_VGA_AS_SINGLE_DEVICE
1615			CONFIG_VIDEO_LOGO
1616			CONFIG_VIDEO_BMP_LOGO
1617
1618		The DIU driver will look for the 'video-mode' environment
1619		variable, and if defined, enable the DIU as a console during
1620		boot.  See the documentation file README.video for a
1621		description of this variable.
1622
1623		CONFIG_VIDEO_VGA
1624
1625		Enable the VGA video / BIOS for x86. The alternative if you
1626		are using coreboot is to use the coreboot frame buffer
1627		driver.
1628
1629
1630- Keyboard Support:
1631		CONFIG_KEYBOARD
1632
1633		Define this to enable a custom keyboard support.
1634		This simply calls drv_keyboard_init() which must be
1635		defined in your board-specific files.
1636		The only board using this so far is RBC823.
1637
1638- LCD Support:	CONFIG_LCD
1639
1640		Define this to enable LCD support (for output to LCD
1641		display); also select one of the supported displays
1642		by defining one of these:
1643
1644		CONFIG_ATMEL_LCD:
1645
1646			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1647
1648		CONFIG_NEC_NL6448AC33:
1649
1650			NEC NL6448AC33-18. Active, color, single scan.
1651
1652		CONFIG_NEC_NL6448BC20
1653
1654			NEC NL6448BC20-08. 6.5", 640x480.
1655			Active, color, single scan.
1656
1657		CONFIG_NEC_NL6448BC33_54
1658
1659			NEC NL6448BC33-54. 10.4", 640x480.
1660			Active, color, single scan.
1661
1662		CONFIG_SHARP_16x9
1663
1664			Sharp 320x240. Active, color, single scan.
1665			It isn't 16x9, and I am not sure what it is.
1666
1667		CONFIG_SHARP_LQ64D341
1668
1669			Sharp LQ64D341 display, 640x480.
1670			Active, color, single scan.
1671
1672		CONFIG_HLD1045
1673
1674			HLD1045 display, 640x480.
1675			Active, color, single scan.
1676
1677		CONFIG_OPTREX_BW
1678
1679			Optrex	 CBL50840-2 NF-FW 99 22 M5
1680			or
1681			Hitachi	 LMG6912RPFC-00T
1682			or
1683			Hitachi	 SP14Q002
1684
1685			320x240. Black & white.
1686
1687		Normally display is black on white background; define
1688		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1689
1690		CONFIG_LCD_ALIGNMENT
1691
1692		Normally the LCD is page-aligned (tyically 4KB). If this is
1693		defined then the LCD will be aligned to this value instead.
1694		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1695		here, since it is cheaper to change data cache settings on
1696		a per-section basis.
1697
1698		CONFIG_CONSOLE_SCROLL_LINES
1699
1700		When the console need to be scrolled, this is the number of
1701		lines to scroll by. It defaults to 1. Increasing this makes
1702		the console jump but can help speed up operation when scrolling
1703		is slow.
1704
1705		CONFIG_LCD_BMP_RLE8
1706
1707		Support drawing of RLE8-compressed bitmaps on the LCD.
1708
1709		CONFIG_I2C_EDID
1710
1711		Enables an 'i2c edid' command which can read EDID
1712		information over I2C from an attached LCD display.
1713
1714- Splash Screen Support: CONFIG_SPLASH_SCREEN
1715
1716		If this option is set, the environment is checked for
1717		a variable "splashimage". If found, the usual display
1718		of logo, copyright and system information on the LCD
1719		is suppressed and the BMP image at the address
1720		specified in "splashimage" is loaded instead. The
1721		console is redirected to the "nulldev", too. This
1722		allows for a "silent" boot where a splash screen is
1723		loaded very quickly after power-on.
1724
1725		CONFIG_SPLASHIMAGE_GUARD
1726
1727		If this option is set, then U-Boot will prevent the environment
1728		variable "splashimage" from being set to a problematic address
1729		(see README.displaying-bmps and README.arm-unaligned-accesses).
1730		This option is useful for targets where, due to alignment
1731		restrictions, an improperly aligned BMP image will cause a data
1732		abort. If you think you will not have problems with unaligned
1733		accesses (for example because your toolchain prevents them)
1734		there is no need to set this option.
1735
1736		CONFIG_SPLASH_SCREEN_ALIGN
1737
1738		If this option is set the splash image can be freely positioned
1739		on the screen. Environment variable "splashpos" specifies the
1740		position as "x,y". If a positive number is given it is used as
1741		number of pixel from left/top. If a negative number is given it
1742		is used as number of pixel from right/bottom. You can also
1743		specify 'm' for centering the image.
1744
1745		Example:
1746		setenv splashpos m,m
1747			=> image at center of screen
1748
1749		setenv splashpos 30,20
1750			=> image at x = 30 and y = 20
1751
1752		setenv splashpos -10,m
1753			=> vertically centered image
1754			   at x = dspWidth - bmpWidth - 9
1755
1756- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1757
1758		If this option is set, additionally to standard BMP
1759		images, gzipped BMP images can be displayed via the
1760		splashscreen support or the bmp command.
1761
1762- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1763
1764		If this option is set, 8-bit RLE compressed BMP images
1765		can be displayed via the splashscreen support or the
1766		bmp command.
1767
1768- Do compresssing for memory range:
1769		CONFIG_CMD_ZIP
1770
1771		If this option is set, it would use zlib deflate method
1772		to compress the specified memory at its best effort.
1773
1774- Compression support:
1775		CONFIG_GZIP
1776
1777		Enabled by default to support gzip compressed images.
1778
1779		CONFIG_BZIP2
1780
1781		If this option is set, support for bzip2 compressed
1782		images is included. If not, only uncompressed and gzip
1783		compressed images are supported.
1784
1785		NOTE: the bzip2 algorithm requires a lot of RAM, so
1786		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1787		be at least 4MB.
1788
1789		CONFIG_LZMA
1790
1791		If this option is set, support for lzma compressed
1792		images is included.
1793
1794		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1795		requires an amount of dynamic memory that is given by the
1796		formula:
1797
1798			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1799
1800		Where lc and lp stand for, respectively, Literal context bits
1801		and Literal pos bits.
1802
1803		This value is upper-bounded by 14MB in the worst case. Anyway,
1804		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1805		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1806		a very small buffer.
1807
1808		Use the lzmainfo tool to determinate the lc and lp values and
1809		then calculate the amount of needed dynamic memory (ensuring
1810		the appropriate CONFIG_SYS_MALLOC_LEN value).
1811
1812		CONFIG_LZO
1813
1814		If this option is set, support for LZO compressed images
1815		is included.
1816
1817- MII/PHY support:
1818		CONFIG_PHY_ADDR
1819
1820		The address of PHY on MII bus.
1821
1822		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1823
1824		The clock frequency of the MII bus
1825
1826		CONFIG_PHY_GIGE
1827
1828		If this option is set, support for speed/duplex
1829		detection of gigabit PHY is included.
1830
1831		CONFIG_PHY_RESET_DELAY
1832
1833		Some PHY like Intel LXT971A need extra delay after
1834		reset before any MII register access is possible.
1835		For such PHY, set this option to the usec delay
1836		required. (minimum 300usec for LXT971A)
1837
1838		CONFIG_PHY_CMD_DELAY (ppc4xx)
1839
1840		Some PHY like Intel LXT971A need extra delay after
1841		command issued before MII status register can be read
1842
1843- Ethernet address:
1844		CONFIG_ETHADDR
1845		CONFIG_ETH1ADDR
1846		CONFIG_ETH2ADDR
1847		CONFIG_ETH3ADDR
1848		CONFIG_ETH4ADDR
1849		CONFIG_ETH5ADDR
1850
1851		Define a default value for Ethernet address to use
1852		for the respective Ethernet interface, in case this
1853		is not determined automatically.
1854
1855- IP address:
1856		CONFIG_IPADDR
1857
1858		Define a default value for the IP address to use for
1859		the default Ethernet interface, in case this is not
1860		determined through e.g. bootp.
1861		(Environment variable "ipaddr")
1862
1863- Server IP address:
1864		CONFIG_SERVERIP
1865
1866		Defines a default value for the IP address of a TFTP
1867		server to contact when using the "tftboot" command.
1868		(Environment variable "serverip")
1869
1870		CONFIG_KEEP_SERVERADDR
1871
1872		Keeps the server's MAC address, in the env 'serveraddr'
1873		for passing to bootargs (like Linux's netconsole option)
1874
1875- Gateway IP address:
1876		CONFIG_GATEWAYIP
1877
1878		Defines a default value for the IP address of the
1879		default router where packets to other networks are
1880		sent to.
1881		(Environment variable "gatewayip")
1882
1883- Subnet mask:
1884		CONFIG_NETMASK
1885
1886		Defines a default value for the subnet mask (or
1887		routing prefix) which is used to determine if an IP
1888		address belongs to the local subnet or needs to be
1889		forwarded through a router.
1890		(Environment variable "netmask")
1891
1892- Multicast TFTP Mode:
1893		CONFIG_MCAST_TFTP
1894
1895		Defines whether you want to support multicast TFTP as per
1896		rfc-2090; for example to work with atftp.  Lets lots of targets
1897		tftp down the same boot image concurrently.  Note: the Ethernet
1898		driver in use must provide a function: mcast() to join/leave a
1899		multicast group.
1900
1901- BOOTP Recovery Mode:
1902		CONFIG_BOOTP_RANDOM_DELAY
1903
1904		If you have many targets in a network that try to
1905		boot using BOOTP, you may want to avoid that all
1906		systems send out BOOTP requests at precisely the same
1907		moment (which would happen for instance at recovery
1908		from a power failure, when all systems will try to
1909		boot, thus flooding the BOOTP server. Defining
1910		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1911		inserted before sending out BOOTP requests. The
1912		following delays are inserted then:
1913
1914		1st BOOTP request:	delay 0 ... 1 sec
1915		2nd BOOTP request:	delay 0 ... 2 sec
1916		3rd BOOTP request:	delay 0 ... 4 sec
1917		4th and following
1918		BOOTP requests:		delay 0 ... 8 sec
1919
1920- DHCP Advanced Options:
1921		You can fine tune the DHCP functionality by defining
1922		CONFIG_BOOTP_* symbols:
1923
1924		CONFIG_BOOTP_SUBNETMASK
1925		CONFIG_BOOTP_GATEWAY
1926		CONFIG_BOOTP_HOSTNAME
1927		CONFIG_BOOTP_NISDOMAIN
1928		CONFIG_BOOTP_BOOTPATH
1929		CONFIG_BOOTP_BOOTFILESIZE
1930		CONFIG_BOOTP_DNS
1931		CONFIG_BOOTP_DNS2
1932		CONFIG_BOOTP_SEND_HOSTNAME
1933		CONFIG_BOOTP_NTPSERVER
1934		CONFIG_BOOTP_TIMEOFFSET
1935		CONFIG_BOOTP_VENDOREX
1936		CONFIG_BOOTP_MAY_FAIL
1937
1938		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1939		environment variable, not the BOOTP server.
1940
1941		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1942		after the configured retry count, the call will fail
1943		instead of starting over.  This can be used to fail over
1944		to Link-local IP address configuration if the DHCP server
1945		is not available.
1946
1947		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1948		serverip from a DHCP server, it is possible that more
1949		than one DNS serverip is offered to the client.
1950		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1951		serverip will be stored in the additional environment
1952		variable "dnsip2". The first DNS serverip is always
1953		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1954		is defined.
1955
1956		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1957		to do a dynamic update of a DNS server. To do this, they
1958		need the hostname of the DHCP requester.
1959		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1960		of the "hostname" environment variable is passed as
1961		option 12 to the DHCP server.
1962
1963		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1964
1965		A 32bit value in microseconds for a delay between
1966		receiving a "DHCP Offer" and sending the "DHCP Request".
1967		This fixes a problem with certain DHCP servers that don't
1968		respond 100% of the time to a "DHCP request". E.g. On an
1969		AT91RM9200 processor running at 180MHz, this delay needed
1970		to be *at least* 15,000 usec before a Windows Server 2003
1971		DHCP server would reply 100% of the time. I recommend at
1972		least 50,000 usec to be safe. The alternative is to hope
1973		that one of the retries will be successful but note that
1974		the DHCP timeout and retry process takes a longer than
1975		this delay.
1976
1977 - Link-local IP address negotiation:
1978		Negotiate with other link-local clients on the local network
1979		for an address that doesn't require explicit configuration.
1980		This is especially useful if a DHCP server cannot be guaranteed
1981		to exist in all environments that the device must operate.
1982
1983		See doc/README.link-local for more information.
1984
1985 - CDP Options:
1986		CONFIG_CDP_DEVICE_ID
1987
1988		The device id used in CDP trigger frames.
1989
1990		CONFIG_CDP_DEVICE_ID_PREFIX
1991
1992		A two character string which is prefixed to the MAC address
1993		of the device.
1994
1995		CONFIG_CDP_PORT_ID
1996
1997		A printf format string which contains the ascii name of
1998		the port. Normally is set to "eth%d" which sets
1999		eth0 for the first Ethernet, eth1 for the second etc.
2000
2001		CONFIG_CDP_CAPABILITIES
2002
2003		A 32bit integer which indicates the device capabilities;
2004		0x00000010 for a normal host which does not forwards.
2005
2006		CONFIG_CDP_VERSION
2007
2008		An ascii string containing the version of the software.
2009
2010		CONFIG_CDP_PLATFORM
2011
2012		An ascii string containing the name of the platform.
2013
2014		CONFIG_CDP_TRIGGER
2015
2016		A 32bit integer sent on the trigger.
2017
2018		CONFIG_CDP_POWER_CONSUMPTION
2019
2020		A 16bit integer containing the power consumption of the
2021		device in .1 of milliwatts.
2022
2023		CONFIG_CDP_APPLIANCE_VLAN_TYPE
2024
2025		A byte containing the id of the VLAN.
2026
2027- Status LED:	CONFIG_STATUS_LED
2028
2029		Several configurations allow to display the current
2030		status using a LED. For instance, the LED will blink
2031		fast while running U-Boot code, stop blinking as
2032		soon as a reply to a BOOTP request was received, and
2033		start blinking slow once the Linux kernel is running
2034		(supported by a status LED driver in the Linux
2035		kernel). Defining CONFIG_STATUS_LED enables this
2036		feature in U-Boot.
2037
2038		Additional options:
2039
2040		CONFIG_GPIO_LED
2041		The status LED can be connected to a GPIO pin.
2042		In such cases, the gpio_led driver can be used as a
2043		status LED backend implementation. Define CONFIG_GPIO_LED
2044		to include the gpio_led driver in the U-Boot binary.
2045
2046		CONFIG_GPIO_LED_INVERTED_TABLE
2047		Some GPIO connected LEDs may have inverted polarity in which
2048		case the GPIO high value corresponds to LED off state and
2049		GPIO low value corresponds to LED on state.
2050		In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
2051		with a list of GPIO LEDs that have inverted polarity.
2052
2053- CAN Support:	CONFIG_CAN_DRIVER
2054
2055		Defining CONFIG_CAN_DRIVER enables CAN driver support
2056		on those systems that support this (optional)
2057		feature, like the TQM8xxL modules.
2058
2059- I2C Support:	CONFIG_SYS_I2C
2060
2061		This enable the NEW i2c subsystem, and will allow you to use
2062		i2c commands at the u-boot command line (as long as you set
2063		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
2064		based realtime clock chips or other i2c devices. See
2065		common/cmd_i2c.c for a description of the command line
2066		interface.
2067
2068		ported i2c driver to the new framework:
2069		- drivers/i2c/soft_i2c.c:
2070		  - activate first bus with CONFIG_SYS_I2C_SOFT define
2071		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
2072		    for defining speed and slave address
2073		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
2074		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
2075		    for defining speed and slave address
2076		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
2077		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
2078		    for defining speed and slave address
2079		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
2080		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
2081		    for defining speed and slave address
2082
2083		- drivers/i2c/fsl_i2c.c:
2084		  - activate i2c driver with CONFIG_SYS_I2C_FSL
2085		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
2086		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
2087		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
2088		    bus.
2089		  - If your board supports a second fsl i2c bus, define
2090		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
2091		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
2092		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
2093		    second bus.
2094
2095		- drivers/i2c/tegra_i2c.c:
2096		  - activate this driver with CONFIG_SYS_I2C_TEGRA
2097		  - This driver adds 4 i2c buses with a fix speed from
2098		    100000 and the slave addr 0!
2099
2100		- drivers/i2c/ppc4xx_i2c.c
2101		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
2102		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
2103		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
2104
2105		- drivers/i2c/i2c_mxc.c
2106		  - activate this driver with CONFIG_SYS_I2C_MXC
2107		  - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
2108		  - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
2109		  - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
2110		  - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
2111		  - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
2112		  - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
2113		If thoses defines are not set, default value is 100000
2114		for speed, and 0 for slave.
2115
2116		- drivers/i2c/rcar_i2c.c:
2117		  - activate this driver with CONFIG_SYS_I2C_RCAR
2118		  - This driver adds 4 i2c buses
2119
2120		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
2121		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
2122		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
2123		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
2124		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
2125		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
2126		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
2127		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
2128		  - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
2129
2130		- drivers/i2c/sh_i2c.c:
2131		  - activate this driver with CONFIG_SYS_I2C_SH
2132		  - This driver adds from 2 to 5 i2c buses
2133
2134		  - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
2135		  - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
2136		  - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
2137		  - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
2138		  - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
2139		  - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
2140		  - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
2141		  - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
2142		  - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
2143		  - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
2144		  - CONFIG_SYS_I2C_SH_BASE5 for setting the register channel 5
2145		  - CONFIG_SYS_I2C_SH_SPEED5 for for the speed channel 5
2146		  - CONFIF_SYS_I2C_SH_NUM_CONTROLLERS for nummber of i2c buses
2147
2148		- drivers/i2c/omap24xx_i2c.c
2149		  - activate this driver with CONFIG_SYS_I2C_OMAP24XX
2150		  - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
2151		  - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
2152		  - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
2153		  - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
2154		  - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
2155		  - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
2156		  - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
2157		  - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
2158		  - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
2159		  - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
2160
2161		- drivers/i2c/zynq_i2c.c
2162		  - activate this driver with CONFIG_SYS_I2C_ZYNQ
2163		  - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
2164		  - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
2165
2166		- drivers/i2c/s3c24x0_i2c.c:
2167		  - activate this driver with CONFIG_SYS_I2C_S3C24X0
2168		  - This driver adds i2c buses (11 for Exynos5250, Exynos5420
2169		    9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
2170		    with a fix speed from 100000 and the slave addr 0!
2171
2172		additional defines:
2173
2174		CONFIG_SYS_NUM_I2C_BUSES
2175		Hold the number of i2c busses you want to use. If you
2176		don't use/have i2c muxes on your i2c bus, this
2177		is equal to CONFIG_SYS_NUM_I2C_ADAPTERS, and you can
2178		omit this define.
2179
2180		CONFIG_SYS_I2C_DIRECT_BUS
2181		define this, if you don't use i2c muxes on your hardware.
2182		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2183		omit this define.
2184
2185		CONFIG_SYS_I2C_MAX_HOPS
2186		define how many muxes are maximal consecutively connected
2187		on one i2c bus. If you not use i2c muxes, omit this
2188		define.
2189
2190		CONFIG_SYS_I2C_BUSES
2191		hold a list of busses you want to use, only used if
2192		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2193		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2194		CONFIG_SYS_NUM_I2C_BUSES = 9:
2195
2196		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
2197					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2198					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2199					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2200					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2201					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2202					{1, {I2C_NULL_HOP}}, \
2203					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2204					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2205					}
2206
2207		which defines
2208			bus 0 on adapter 0 without a mux
2209			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2210			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2211			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2212			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2213			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2214			bus 6 on adapter 1 without a mux
2215			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2216			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2217
2218		If you do not have i2c muxes on your board, omit this define.
2219
2220- Legacy I2C Support:	CONFIG_HARD_I2C
2221
2222		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2223		provides the following compelling advantages:
2224
2225		- more than one i2c adapter is usable
2226		- approved multibus support
2227		- better i2c mux support
2228
2229		** Please consider updating your I2C driver now. **
2230
2231		These enable legacy I2C serial bus commands. Defining
2232		CONFIG_HARD_I2C will include the appropriate I2C driver
2233		for the selected CPU.
2234
2235		This will allow you to use i2c commands at the u-boot
2236		command line (as long as you set CONFIG_CMD_I2C in
2237		CONFIG_COMMANDS) and communicate with i2c based realtime
2238		clock chips. See common/cmd_i2c.c for a description of the
2239		command line interface.
2240
2241		CONFIG_HARD_I2C selects a hardware I2C controller.
2242
2243		There are several other quantities that must also be
2244		defined when you define CONFIG_HARD_I2C.
2245
2246		In both cases you will need to define CONFIG_SYS_I2C_SPEED
2247		to be the frequency (in Hz) at which you wish your i2c bus
2248		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2249		the CPU's i2c node address).
2250
2251		Now, the u-boot i2c code for the mpc8xx
2252		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2253		and so its address should therefore be cleared to 0 (See,
2254		eg, MPC823e User's Manual p.16-473). So, set
2255		CONFIG_SYS_I2C_SLAVE to 0.
2256
2257		CONFIG_SYS_I2C_INIT_MPC5XXX
2258
2259		When a board is reset during an i2c bus transfer
2260		chips might think that the current transfer is still
2261		in progress.  Reset the slave devices by sending start
2262		commands until the slave device responds.
2263
2264		That's all that's required for CONFIG_HARD_I2C.
2265
2266		If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2267		then the following macros need to be defined (examples are
2268		from include/configs/lwmon.h):
2269
2270		I2C_INIT
2271
2272		(Optional). Any commands necessary to enable the I2C
2273		controller or configure ports.
2274
2275		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2276
2277		I2C_PORT
2278
2279		(Only for MPC8260 CPU). The I/O port to use (the code
2280		assumes both bits are on the same port). Valid values
2281		are 0..3 for ports A..D.
2282
2283		I2C_ACTIVE
2284
2285		The code necessary to make the I2C data line active
2286		(driven).  If the data line is open collector, this
2287		define can be null.
2288
2289		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2290
2291		I2C_TRISTATE
2292
2293		The code necessary to make the I2C data line tri-stated
2294		(inactive).  If the data line is open collector, this
2295		define can be null.
2296
2297		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2298
2299		I2C_READ
2300
2301		Code that returns true if the I2C data line is high,
2302		false if it is low.
2303
2304		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2305
2306		I2C_SDA(bit)
2307
2308		If <bit> is true, sets the I2C data line high. If it
2309		is false, it clears it (low).
2310
2311		eg: #define I2C_SDA(bit) \
2312			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2313			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2314
2315		I2C_SCL(bit)
2316
2317		If <bit> is true, sets the I2C clock line high. If it
2318		is false, it clears it (low).
2319
2320		eg: #define I2C_SCL(bit) \
2321			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2322			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2323
2324		I2C_DELAY
2325
2326		This delay is invoked four times per clock cycle so this
2327		controls the rate of data transfer.  The data rate thus
2328		is 1 / (I2C_DELAY * 4). Often defined to be something
2329		like:
2330
2331		#define I2C_DELAY  udelay(2)
2332
2333		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2334
2335		If your arch supports the generic GPIO framework (asm/gpio.h),
2336		then you may alternatively define the two GPIOs that are to be
2337		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2338		have GPIO-based defaults assigned to them as appropriate.
2339
2340		You should define these to the GPIO value as given directly to
2341		the generic GPIO functions.
2342
2343		CONFIG_SYS_I2C_INIT_BOARD
2344
2345		When a board is reset during an i2c bus transfer
2346		chips might think that the current transfer is still
2347		in progress. On some boards it is possible to access
2348		the i2c SCLK line directly, either by using the
2349		processor pin as a GPIO or by having a second pin
2350		connected to the bus. If this option is defined a
2351		custom i2c_init_board() routine in boards/xxx/board.c
2352		is run early in the boot sequence.
2353
2354		CONFIG_SYS_I2C_BOARD_LATE_INIT
2355
2356		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2357		defined a custom i2c_board_late_init() routine in
2358		boards/xxx/board.c is run AFTER the operations in i2c_init()
2359		is completed. This callpoint can be used to unreset i2c bus
2360		using CPU i2c controller register accesses for CPUs whose i2c
2361		controller provide such a method. It is called at the end of
2362		i2c_init() to allow i2c_init operations to setup the i2c bus
2363		controller on the CPU (e.g. setting bus speed & slave address).
2364
2365		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2366
2367		This option enables configuration of bi_iic_fast[] flags
2368		in u-boot bd_info structure based on u-boot environment
2369		variable "i2cfast". (see also i2cfast)
2370
2371		CONFIG_I2C_MULTI_BUS
2372
2373		This option allows the use of multiple I2C buses, each of which
2374		must have a controller.	 At any point in time, only one bus is
2375		active.	 To switch to a different bus, use the 'i2c dev' command.
2376		Note that bus numbering is zero-based.
2377
2378		CONFIG_SYS_I2C_NOPROBES
2379
2380		This option specifies a list of I2C devices that will be skipped
2381		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2382		is set, specify a list of bus-device pairs.  Otherwise, specify
2383		a 1D array of device addresses
2384
2385		e.g.
2386			#undef	CONFIG_I2C_MULTI_BUS
2387			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2388
2389		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2390
2391			#define CONFIG_I2C_MULTI_BUS
2392			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2393
2394		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2395
2396		CONFIG_SYS_SPD_BUS_NUM
2397
2398		If defined, then this indicates the I2C bus number for DDR SPD.
2399		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2400
2401		CONFIG_SYS_RTC_BUS_NUM
2402
2403		If defined, then this indicates the I2C bus number for the RTC.
2404		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2405
2406		CONFIG_SYS_DTT_BUS_NUM
2407
2408		If defined, then this indicates the I2C bus number for the DTT.
2409		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2410
2411		CONFIG_SYS_I2C_DTT_ADDR:
2412
2413		If defined, specifies the I2C address of the DTT device.
2414		If not defined, then U-Boot uses predefined value for
2415		specified DTT device.
2416
2417		CONFIG_SOFT_I2C_READ_REPEATED_START
2418
2419		defining this will force the i2c_read() function in
2420		the soft_i2c driver to perform an I2C repeated start
2421		between writing the address pointer and reading the
2422		data.  If this define is omitted the default behaviour
2423		of doing a stop-start sequence will be used.  Most I2C
2424		devices can use either method, but some require one or
2425		the other.
2426
2427- SPI Support:	CONFIG_SPI
2428
2429		Enables SPI driver (so far only tested with
2430		SPI EEPROM, also an instance works with Crystal A/D and
2431		D/As on the SACSng board)
2432
2433		CONFIG_SH_SPI
2434
2435		Enables the driver for SPI controller on SuperH. Currently
2436		only SH7757 is supported.
2437
2438		CONFIG_SPI_X
2439
2440		Enables extended (16-bit) SPI EEPROM addressing.
2441		(symmetrical to CONFIG_I2C_X)
2442
2443		CONFIG_SOFT_SPI
2444
2445		Enables a software (bit-bang) SPI driver rather than
2446		using hardware support. This is a general purpose
2447		driver that only requires three general I/O port pins
2448		(two outputs, one input) to function. If this is
2449		defined, the board configuration must define several
2450		SPI configuration items (port pins to use, etc). For
2451		an example, see include/configs/sacsng.h.
2452
2453		CONFIG_HARD_SPI
2454
2455		Enables a hardware SPI driver for general-purpose reads
2456		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2457		must define a list of chip-select function pointers.
2458		Currently supported on some MPC8xxx processors.	 For an
2459		example, see include/configs/mpc8349emds.h.
2460
2461		CONFIG_MXC_SPI
2462
2463		Enables the driver for the SPI controllers on i.MX and MXC
2464		SoCs. Currently i.MX31/35/51 are supported.
2465
2466- FPGA Support: CONFIG_FPGA
2467
2468		Enables FPGA subsystem.
2469
2470		CONFIG_FPGA_<vendor>
2471
2472		Enables support for specific chip vendors.
2473		(ALTERA, XILINX)
2474
2475		CONFIG_FPGA_<family>
2476
2477		Enables support for FPGA family.
2478		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2479
2480		CONFIG_FPGA_COUNT
2481
2482		Specify the number of FPGA devices to support.
2483
2484		CONFIG_SYS_FPGA_PROG_FEEDBACK
2485
2486		Enable printing of hash marks during FPGA configuration.
2487
2488		CONFIG_SYS_FPGA_CHECK_BUSY
2489
2490		Enable checks on FPGA configuration interface busy
2491		status by the configuration function. This option
2492		will require a board or device specific function to
2493		be written.
2494
2495		CONFIG_FPGA_DELAY
2496
2497		If defined, a function that provides delays in the FPGA
2498		configuration driver.
2499
2500		CONFIG_SYS_FPGA_CHECK_CTRLC
2501		Allow Control-C to interrupt FPGA configuration
2502
2503		CONFIG_SYS_FPGA_CHECK_ERROR
2504
2505		Check for configuration errors during FPGA bitfile
2506		loading. For example, abort during Virtex II
2507		configuration if the INIT_B line goes low (which
2508		indicated a CRC error).
2509
2510		CONFIG_SYS_FPGA_WAIT_INIT
2511
2512		Maximum time to wait for the INIT_B line to deassert
2513		after PROB_B has been deasserted during a Virtex II
2514		FPGA configuration sequence. The default time is 500
2515		ms.
2516
2517		CONFIG_SYS_FPGA_WAIT_BUSY
2518
2519		Maximum time to wait for BUSY to deassert during
2520		Virtex II FPGA configuration. The default is 5 ms.
2521
2522		CONFIG_SYS_FPGA_WAIT_CONFIG
2523
2524		Time to wait after FPGA configuration. The default is
2525		200 ms.
2526
2527- Configuration Management:
2528		CONFIG_IDENT_STRING
2529
2530		If defined, this string will be added to the U-Boot
2531		version information (U_BOOT_VERSION)
2532
2533- Vendor Parameter Protection:
2534
2535		U-Boot considers the values of the environment
2536		variables "serial#" (Board Serial Number) and
2537		"ethaddr" (Ethernet Address) to be parameters that
2538		are set once by the board vendor / manufacturer, and
2539		protects these variables from casual modification by
2540		the user. Once set, these variables are read-only,
2541		and write or delete attempts are rejected. You can
2542		change this behaviour:
2543
2544		If CONFIG_ENV_OVERWRITE is #defined in your config
2545		file, the write protection for vendor parameters is
2546		completely disabled. Anybody can change or delete
2547		these parameters.
2548
2549		Alternatively, if you #define _both_ CONFIG_ETHADDR
2550		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2551		Ethernet address is installed in the environment,
2552		which can be changed exactly ONCE by the user. [The
2553		serial# is unaffected by this, i. e. it remains
2554		read-only.]
2555
2556		The same can be accomplished in a more flexible way
2557		for any variable by configuring the type of access
2558		to allow for those variables in the ".flags" variable
2559		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2560
2561- Protected RAM:
2562		CONFIG_PRAM
2563
2564		Define this variable to enable the reservation of
2565		"protected RAM", i. e. RAM which is not overwritten
2566		by U-Boot. Define CONFIG_PRAM to hold the number of
2567		kB you want to reserve for pRAM. You can overwrite
2568		this default value by defining an environment
2569		variable "pram" to the number of kB you want to
2570		reserve. Note that the board info structure will
2571		still show the full amount of RAM. If pRAM is
2572		reserved, a new environment variable "mem" will
2573		automatically be defined to hold the amount of
2574		remaining RAM in a form that can be passed as boot
2575		argument to Linux, for instance like that:
2576
2577			setenv bootargs ... mem=\${mem}
2578			saveenv
2579
2580		This way you can tell Linux not to use this memory,
2581		either, which results in a memory region that will
2582		not be affected by reboots.
2583
2584		*WARNING* If your board configuration uses automatic
2585		detection of the RAM size, you must make sure that
2586		this memory test is non-destructive. So far, the
2587		following board configurations are known to be
2588		"pRAM-clean":
2589
2590			IVMS8, IVML24, SPD8xx, TQM8xxL,
2591			HERMES, IP860, RPXlite, LWMON,
2592			FLAGADM, TQM8260
2593
2594- Access to physical memory region (> 4GB)
2595		Some basic support is provided for operations on memory not
2596		normally accessible to U-Boot - e.g. some architectures
2597		support access to more than 4GB of memory on 32-bit
2598		machines using physical address extension or similar.
2599		Define CONFIG_PHYSMEM to access this basic support, which
2600		currently only supports clearing the memory.
2601
2602- Error Recovery:
2603		CONFIG_PANIC_HANG
2604
2605		Define this variable to stop the system in case of a
2606		fatal error, so that you have to reset it manually.
2607		This is probably NOT a good idea for an embedded
2608		system where you want the system to reboot
2609		automatically as fast as possible, but it may be
2610		useful during development since you can try to debug
2611		the conditions that lead to the situation.
2612
2613		CONFIG_NET_RETRY_COUNT
2614
2615		This variable defines the number of retries for
2616		network operations like ARP, RARP, TFTP, or BOOTP
2617		before giving up the operation. If not defined, a
2618		default value of 5 is used.
2619
2620		CONFIG_ARP_TIMEOUT
2621
2622		Timeout waiting for an ARP reply in milliseconds.
2623
2624		CONFIG_NFS_TIMEOUT
2625
2626		Timeout in milliseconds used in NFS protocol.
2627		If you encounter "ERROR: Cannot umount" in nfs command,
2628		try longer timeout such as
2629		#define CONFIG_NFS_TIMEOUT 10000UL
2630
2631- Command Interpreter:
2632		CONFIG_AUTO_COMPLETE
2633
2634		Enable auto completion of commands using TAB.
2635
2636		Note that this feature has NOT been implemented yet
2637		for the "hush" shell.
2638
2639
2640		CONFIG_SYS_HUSH_PARSER
2641
2642		Define this variable to enable the "hush" shell (from
2643		Busybox) as command line interpreter, thus enabling
2644		powerful command line syntax like
2645		if...then...else...fi conditionals or `&&' and '||'
2646		constructs ("shell scripts").
2647
2648		If undefined, you get the old, much simpler behaviour
2649		with a somewhat smaller memory footprint.
2650
2651
2652		CONFIG_SYS_PROMPT_HUSH_PS2
2653
2654		This defines the secondary prompt string, which is
2655		printed when the command interpreter needs more input
2656		to complete a command. Usually "> ".
2657
2658	Note:
2659
2660		In the current implementation, the local variables
2661		space and global environment variables space are
2662		separated. Local variables are those you define by
2663		simply typing `name=value'. To access a local
2664		variable later on, you have write `$name' or
2665		`${name}'; to execute the contents of a variable
2666		directly type `$name' at the command prompt.
2667
2668		Global environment variables are those you use
2669		setenv/printenv to work with. To run a command stored
2670		in such a variable, you need to use the run command,
2671		and you must not use the '$' sign to access them.
2672
2673		To store commands and special characters in a
2674		variable, please use double quotation marks
2675		surrounding the whole text of the variable, instead
2676		of the backslashes before semicolons and special
2677		symbols.
2678
2679- Commandline Editing and History:
2680		CONFIG_CMDLINE_EDITING
2681
2682		Enable editing and History functions for interactive
2683		commandline input operations
2684
2685- Default Environment:
2686		CONFIG_EXTRA_ENV_SETTINGS
2687
2688		Define this to contain any number of null terminated
2689		strings (variable = value pairs) that will be part of
2690		the default environment compiled into the boot image.
2691
2692		For example, place something like this in your
2693		board's config file:
2694
2695		#define CONFIG_EXTRA_ENV_SETTINGS \
2696			"myvar1=value1\0" \
2697			"myvar2=value2\0"
2698
2699		Warning: This method is based on knowledge about the
2700		internal format how the environment is stored by the
2701		U-Boot code. This is NOT an official, exported
2702		interface! Although it is unlikely that this format
2703		will change soon, there is no guarantee either.
2704		You better know what you are doing here.
2705
2706		Note: overly (ab)use of the default environment is
2707		discouraged. Make sure to check other ways to preset
2708		the environment like the "source" command or the
2709		boot command first.
2710
2711		CONFIG_ENV_VARS_UBOOT_CONFIG
2712
2713		Define this in order to add variables describing the
2714		U-Boot build configuration to the default environment.
2715		These will be named arch, cpu, board, vendor, and soc.
2716
2717		Enabling this option will cause the following to be defined:
2718
2719		- CONFIG_SYS_ARCH
2720		- CONFIG_SYS_CPU
2721		- CONFIG_SYS_BOARD
2722		- CONFIG_SYS_VENDOR
2723		- CONFIG_SYS_SOC
2724
2725		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2726
2727		Define this in order to add variables describing certain
2728		run-time determined information about the hardware to the
2729		environment.  These will be named board_name, board_rev.
2730
2731		CONFIG_DELAY_ENVIRONMENT
2732
2733		Normally the environment is loaded when the board is
2734		intialised so that it is available to U-Boot. This inhibits
2735		that so that the environment is not available until
2736		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2737		this is instead controlled by the value of
2738		/config/load-environment.
2739
2740- DataFlash Support:
2741		CONFIG_HAS_DATAFLASH
2742
2743		Defining this option enables DataFlash features and
2744		allows to read/write in Dataflash via the standard
2745		commands cp, md...
2746
2747- Serial Flash support
2748		CONFIG_CMD_SF
2749
2750		Defining this option enables SPI flash commands
2751		'sf probe/read/write/erase/update'.
2752
2753		Usage requires an initial 'probe' to define the serial
2754		flash parameters, followed by read/write/erase/update
2755		commands.
2756
2757		The following defaults may be provided by the platform
2758		to handle the common case when only a single serial
2759		flash is present on the system.
2760
2761		CONFIG_SF_DEFAULT_BUS		Bus identifier
2762		CONFIG_SF_DEFAULT_CS		Chip-select
2763		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2764		CONFIG_SF_DEFAULT_SPEED		in Hz
2765
2766		CONFIG_CMD_SF_TEST
2767
2768		Define this option to include a destructive SPI flash
2769		test ('sf test').
2770
2771		CONFIG_SPI_FLASH_BAR		Ban/Extended Addr Reg
2772
2773		Define this option to use the Bank addr/Extended addr
2774		support on SPI flashes which has size > 16Mbytes.
2775
2776		CONFIG_SF_DUAL_FLASH		Dual flash memories
2777
2778		Define this option to use dual flash support where two flash
2779		memories can be connected with a given cs line.
2780		currently Xilinx Zynq qspi support these type of connections.
2781
2782- SystemACE Support:
2783		CONFIG_SYSTEMACE
2784
2785		Adding this option adds support for Xilinx SystemACE
2786		chips attached via some sort of local bus. The address
2787		of the chip must also be defined in the
2788		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2789
2790		#define CONFIG_SYSTEMACE
2791		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2792
2793		When SystemACE support is added, the "ace" device type
2794		becomes available to the fat commands, i.e. fatls.
2795
2796- TFTP Fixed UDP Port:
2797		CONFIG_TFTP_PORT
2798
2799		If this is defined, the environment variable tftpsrcp
2800		is used to supply the TFTP UDP source port value.
2801		If tftpsrcp isn't defined, the normal pseudo-random port
2802		number generator is used.
2803
2804		Also, the environment variable tftpdstp is used to supply
2805		the TFTP UDP destination port value.  If tftpdstp isn't
2806		defined, the normal port 69 is used.
2807
2808		The purpose for tftpsrcp is to allow a TFTP server to
2809		blindly start the TFTP transfer using the pre-configured
2810		target IP address and UDP port. This has the effect of
2811		"punching through" the (Windows XP) firewall, allowing
2812		the remainder of the TFTP transfer to proceed normally.
2813		A better solution is to properly configure the firewall,
2814		but sometimes that is not allowed.
2815
2816- Hashing support:
2817		CONFIG_CMD_HASH
2818
2819		This enables a generic 'hash' command which can produce
2820		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
2821
2822		CONFIG_HASH_VERIFY
2823
2824		Enable the hash verify command (hash -v). This adds to code
2825		size a little.
2826
2827		CONFIG_SHA1 - support SHA1 hashing
2828		CONFIG_SHA256 - support SHA256 hashing
2829
2830		Note: There is also a sha1sum command, which should perhaps
2831		be deprecated in favour of 'hash sha1'.
2832
2833- Freescale i.MX specific commands:
2834		CONFIG_CMD_HDMIDETECT
2835		This enables 'hdmidet' command which returns true if an
2836		HDMI monitor is detected.  This command is i.MX 6 specific.
2837
2838		CONFIG_CMD_BMODE
2839		This enables the 'bmode' (bootmode) command for forcing
2840		a boot from specific media.
2841
2842		This is useful for forcing the ROM's usb downloader to
2843		activate upon a watchdog reset which is nice when iterating
2844		on U-Boot.  Using the reset button or running bmode normal
2845		will set it back to normal.  This command currently
2846		supports i.MX53 and i.MX6.
2847
2848- Signing support:
2849		CONFIG_RSA
2850
2851		This enables the RSA algorithm used for FIT image verification
2852		in U-Boot. See doc/uImage.FIT/signature.txt for more information.
2853
2854		The signing part is build into mkimage regardless of this
2855		option.
2856
2857- bootcount support:
2858		CONFIG_BOOTCOUNT_LIMIT
2859
2860		This enables the bootcounter support, see:
2861		http://www.denx.de/wiki/DULG/UBootBootCountLimit
2862
2863		CONFIG_AT91SAM9XE
2864		enable special bootcounter support on at91sam9xe based boards.
2865		CONFIG_BLACKFIN
2866		enable special bootcounter support on blackfin based boards.
2867		CONFIG_SOC_DA8XX
2868		enable special bootcounter support on da850 based boards.
2869		CONFIG_BOOTCOUNT_RAM
2870		enable support for the bootcounter in RAM
2871		CONFIG_BOOTCOUNT_I2C
2872		enable support for the bootcounter on an i2c (like RTC) device.
2873			CONFIG_SYS_I2C_RTC_ADDR = i2c chip address
2874			CONFIG_SYS_BOOTCOUNT_ADDR = i2c addr which is used for
2875						    the bootcounter.
2876			CONFIG_BOOTCOUNT_ALEN = address len
2877
2878- Show boot progress:
2879		CONFIG_SHOW_BOOT_PROGRESS
2880
2881		Defining this option allows to add some board-
2882		specific code (calling a user-provided function
2883		"show_boot_progress(int)") that enables you to show
2884		the system's boot progress on some display (for
2885		example, some LED's) on your board. At the moment,
2886		the following checkpoints are implemented:
2887
2888- Detailed boot stage timing
2889		CONFIG_BOOTSTAGE
2890		Define this option to get detailed timing of each stage
2891		of the boot process.
2892
2893		CONFIG_BOOTSTAGE_USER_COUNT
2894		This is the number of available user bootstage records.
2895		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
2896		a new ID will be allocated from this stash. If you exceed
2897		the limit, recording will stop.
2898
2899		CONFIG_BOOTSTAGE_REPORT
2900		Define this to print a report before boot, similar to this:
2901
2902		Timer summary in microseconds:
2903		       Mark    Elapsed  Stage
2904			  0          0  reset
2905		  3,575,678  3,575,678  board_init_f start
2906		  3,575,695         17  arch_cpu_init A9
2907		  3,575,777         82  arch_cpu_init done
2908		  3,659,598     83,821  board_init_r start
2909		  3,910,375    250,777  main_loop
2910		 29,916,167 26,005,792  bootm_start
2911		 30,361,327    445,160  start_kernel
2912
2913		CONFIG_CMD_BOOTSTAGE
2914		Add a 'bootstage' command which supports printing a report
2915		and un/stashing of bootstage data.
2916
2917		CONFIG_BOOTSTAGE_FDT
2918		Stash the bootstage information in the FDT. A root 'bootstage'
2919		node is created with each bootstage id as a child. Each child
2920		has a 'name' property and either 'mark' containing the
2921		mark time in microsecond, or 'accum' containing the
2922		accumulated time for that bootstage id in microseconds.
2923		For example:
2924
2925		bootstage {
2926			154 {
2927				name = "board_init_f";
2928				mark = <3575678>;
2929			};
2930			170 {
2931				name = "lcd";
2932				accum = <33482>;
2933			};
2934		};
2935
2936		Code in the Linux kernel can find this in /proc/devicetree.
2937
2938Legacy uImage format:
2939
2940  Arg	Where			When
2941    1	common/cmd_bootm.c	before attempting to boot an image
2942   -1	common/cmd_bootm.c	Image header has bad	 magic number
2943    2	common/cmd_bootm.c	Image header has correct magic number
2944   -2	common/cmd_bootm.c	Image header has bad	 checksum
2945    3	common/cmd_bootm.c	Image header has correct checksum
2946   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2947    4	common/cmd_bootm.c	Image data   has correct checksum
2948   -4	common/cmd_bootm.c	Image is for unsupported architecture
2949    5	common/cmd_bootm.c	Architecture check OK
2950   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2951    6	common/cmd_bootm.c	Image Type check OK
2952   -6	common/cmd_bootm.c	gunzip uncompression error
2953   -7	common/cmd_bootm.c	Unimplemented compression type
2954    7	common/cmd_bootm.c	Uncompression OK
2955    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2956   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2957
2958    9	common/image.c		Start initial ramdisk verification
2959  -10	common/image.c		Ramdisk header has bad	   magic number
2960  -11	common/image.c		Ramdisk header has bad	   checksum
2961   10	common/image.c		Ramdisk header is OK
2962  -12	common/image.c		Ramdisk data   has bad	   checksum
2963   11	common/image.c		Ramdisk data   has correct checksum
2964   12	common/image.c		Ramdisk verification complete, start loading
2965  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2966   13	common/image.c		Start multifile image verification
2967   14	common/image.c		No initial ramdisk, no multifile, continue.
2968
2969   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2970
2971  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2972  -31	post/post.c		POST test failed, detected by post_output_backlog()
2973  -32	post/post.c		POST test failed, detected by post_run_single()
2974
2975   34	common/cmd_doc.c	before loading a Image from a DOC device
2976  -35	common/cmd_doc.c	Bad usage of "doc" command
2977   35	common/cmd_doc.c	correct usage of "doc" command
2978  -36	common/cmd_doc.c	No boot device
2979   36	common/cmd_doc.c	correct boot device
2980  -37	common/cmd_doc.c	Unknown Chip ID on boot device
2981   37	common/cmd_doc.c	correct chip ID found, device available
2982  -38	common/cmd_doc.c	Read Error on boot device
2983   38	common/cmd_doc.c	reading Image header from DOC device OK
2984  -39	common/cmd_doc.c	Image header has bad magic number
2985   39	common/cmd_doc.c	Image header has correct magic number
2986  -40	common/cmd_doc.c	Error reading Image from DOC device
2987   40	common/cmd_doc.c	Image header has correct magic number
2988   41	common/cmd_ide.c	before loading a Image from a IDE device
2989  -42	common/cmd_ide.c	Bad usage of "ide" command
2990   42	common/cmd_ide.c	correct usage of "ide" command
2991  -43	common/cmd_ide.c	No boot device
2992   43	common/cmd_ide.c	boot device found
2993  -44	common/cmd_ide.c	Device not available
2994   44	common/cmd_ide.c	Device available
2995  -45	common/cmd_ide.c	wrong partition selected
2996   45	common/cmd_ide.c	partition selected
2997  -46	common/cmd_ide.c	Unknown partition table
2998   46	common/cmd_ide.c	valid partition table found
2999  -47	common/cmd_ide.c	Invalid partition type
3000   47	common/cmd_ide.c	correct partition type
3001  -48	common/cmd_ide.c	Error reading Image Header on boot device
3002   48	common/cmd_ide.c	reading Image Header from IDE device OK
3003  -49	common/cmd_ide.c	Image header has bad magic number
3004   49	common/cmd_ide.c	Image header has correct magic number
3005  -50	common/cmd_ide.c	Image header has bad	 checksum
3006   50	common/cmd_ide.c	Image header has correct checksum
3007  -51	common/cmd_ide.c	Error reading Image from IDE device
3008   51	common/cmd_ide.c	reading Image from IDE device OK
3009   52	common/cmd_nand.c	before loading a Image from a NAND device
3010  -53	common/cmd_nand.c	Bad usage of "nand" command
3011   53	common/cmd_nand.c	correct usage of "nand" command
3012  -54	common/cmd_nand.c	No boot device
3013   54	common/cmd_nand.c	boot device found
3014  -55	common/cmd_nand.c	Unknown Chip ID on boot device
3015   55	common/cmd_nand.c	correct chip ID found, device available
3016  -56	common/cmd_nand.c	Error reading Image Header on boot device
3017   56	common/cmd_nand.c	reading Image Header from NAND device OK
3018  -57	common/cmd_nand.c	Image header has bad magic number
3019   57	common/cmd_nand.c	Image header has correct magic number
3020  -58	common/cmd_nand.c	Error reading Image from NAND device
3021   58	common/cmd_nand.c	reading Image from NAND device OK
3022
3023  -60	common/env_common.c	Environment has a bad CRC, using default
3024
3025   64	net/eth.c		starting with Ethernet configuration.
3026  -64	net/eth.c		no Ethernet found.
3027   65	net/eth.c		Ethernet found.
3028
3029  -80	common/cmd_net.c	usage wrong
3030   80	common/cmd_net.c	before calling NetLoop()
3031  -81	common/cmd_net.c	some error in NetLoop() occurred
3032   81	common/cmd_net.c	NetLoop() back without error
3033  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
3034   82	common/cmd_net.c	trying automatic boot
3035   83	common/cmd_net.c	running "source" command
3036  -83	common/cmd_net.c	some error in automatic boot or "source" command
3037   84	common/cmd_net.c	end without errors
3038
3039FIT uImage format:
3040
3041  Arg	Where			When
3042  100	common/cmd_bootm.c	Kernel FIT Image has correct format
3043 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
3044  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
3045 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
3046  102	common/cmd_bootm.c	Kernel unit name specified
3047 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
3048  103	common/cmd_bootm.c	Found configuration node
3049  104	common/cmd_bootm.c	Got kernel subimage node offset
3050 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
3051  105	common/cmd_bootm.c	Kernel subimage hash verification OK
3052 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
3053  106	common/cmd_bootm.c	Architecture check OK
3054 -106	common/cmd_bootm.c	Kernel subimage has wrong type
3055  107	common/cmd_bootm.c	Kernel subimage type OK
3056 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
3057  108	common/cmd_bootm.c	Got kernel subimage data/size
3058 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
3059 -109	common/cmd_bootm.c	Can't get kernel subimage type
3060 -110	common/cmd_bootm.c	Can't get kernel subimage comp
3061 -111	common/cmd_bootm.c	Can't get kernel subimage os
3062 -112	common/cmd_bootm.c	Can't get kernel subimage load address
3063 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
3064
3065  120	common/image.c		Start initial ramdisk verification
3066 -120	common/image.c		Ramdisk FIT image has incorrect format
3067  121	common/image.c		Ramdisk FIT image has correct format
3068  122	common/image.c		No ramdisk subimage unit name, using configuration
3069 -122	common/image.c		Can't get configuration for ramdisk subimage
3070  123	common/image.c		Ramdisk unit name specified
3071 -124	common/image.c		Can't get ramdisk subimage node offset
3072  125	common/image.c		Got ramdisk subimage node offset
3073 -125	common/image.c		Ramdisk subimage hash verification failed
3074  126	common/image.c		Ramdisk subimage hash verification OK
3075 -126	common/image.c		Ramdisk subimage for unsupported architecture
3076  127	common/image.c		Architecture check OK
3077 -127	common/image.c		Can't get ramdisk subimage data/size
3078  128	common/image.c		Got ramdisk subimage data/size
3079  129	common/image.c		Can't get ramdisk load address
3080 -129	common/image.c		Got ramdisk load address
3081
3082 -130	common/cmd_doc.c	Incorrect FIT image format
3083  131	common/cmd_doc.c	FIT image format OK
3084
3085 -140	common/cmd_ide.c	Incorrect FIT image format
3086  141	common/cmd_ide.c	FIT image format OK
3087
3088 -150	common/cmd_nand.c	Incorrect FIT image format
3089  151	common/cmd_nand.c	FIT image format OK
3090
3091- FIT image support:
3092		CONFIG_FIT
3093		Enable support for the FIT uImage format.
3094
3095		CONFIG_FIT_BEST_MATCH
3096		When no configuration is explicitly selected, default to the
3097		one whose fdt's compatibility field best matches that of
3098		U-Boot itself. A match is considered "best" if it matches the
3099		most specific compatibility entry of U-Boot's fdt's root node.
3100		The order of entries in the configuration's fdt is ignored.
3101
3102		CONFIG_FIT_SIGNATURE
3103		This option enables signature verification of FIT uImages,
3104		using a hash signed and verified using RSA. See
3105		doc/uImage.FIT/signature.txt for more details.
3106
3107- Standalone program support:
3108		CONFIG_STANDALONE_LOAD_ADDR
3109
3110		This option defines a board specific value for the
3111		address where standalone program gets loaded, thus
3112		overwriting the architecture dependent default
3113		settings.
3114
3115- Frame Buffer Address:
3116		CONFIG_FB_ADDR
3117
3118		Define CONFIG_FB_ADDR if you want to use specific
3119		address for frame buffer.  This is typically the case
3120		when using a graphics controller has separate video
3121		memory.  U-Boot will then place the frame buffer at
3122		the given address instead of dynamically reserving it
3123		in system RAM by calling lcd_setmem(), which grabs
3124		the memory for the frame buffer depending on the
3125		configured panel size.
3126
3127		Please see board_init_f function.
3128
3129- Automatic software updates via TFTP server
3130		CONFIG_UPDATE_TFTP
3131		CONFIG_UPDATE_TFTP_CNT_MAX
3132		CONFIG_UPDATE_TFTP_MSEC_MAX
3133
3134		These options enable and control the auto-update feature;
3135		for a more detailed description refer to doc/README.update.
3136
3137- MTD Support (mtdparts command, UBI support)
3138		CONFIG_MTD_DEVICE
3139
3140		Adds the MTD device infrastructure from the Linux kernel.
3141		Needed for mtdparts command support.
3142
3143		CONFIG_MTD_PARTITIONS
3144
3145		Adds the MTD partitioning infrastructure from the Linux
3146		kernel. Needed for UBI support.
3147
3148- UBI support
3149		CONFIG_CMD_UBI
3150
3151		Adds commands for interacting with MTD partitions formatted
3152		with the UBI flash translation layer
3153
3154		Requires also defining CONFIG_RBTREE
3155
3156		CONFIG_UBI_SILENCE_MSG
3157
3158		Make the verbose messages from UBI stop printing.  This leaves
3159		warnings and errors enabled.
3160
3161- UBIFS support
3162		CONFIG_CMD_UBIFS
3163
3164		Adds commands for interacting with UBI volumes formatted as
3165		UBIFS.  UBIFS is read-only in u-boot.
3166
3167		Requires UBI support as well as CONFIG_LZO
3168
3169		CONFIG_UBIFS_SILENCE_MSG
3170
3171		Make the verbose messages from UBIFS stop printing.  This leaves
3172		warnings and errors enabled.
3173
3174- SPL framework
3175		CONFIG_SPL
3176		Enable building of SPL globally.
3177
3178		CONFIG_SPL_LDSCRIPT
3179		LDSCRIPT for linking the SPL binary.
3180
3181		CONFIG_SPL_MAX_FOOTPRINT
3182		Maximum size in memory allocated to the SPL, BSS included.
3183		When defined, the linker checks that the actual memory
3184		used by SPL from _start to __bss_end does not exceed it.
3185		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3186		must not be both defined at the same time.
3187
3188		CONFIG_SPL_MAX_SIZE
3189		Maximum size of the SPL image (text, data, rodata, and
3190		linker lists sections), BSS excluded.
3191		When defined, the linker checks that the actual size does
3192		not exceed it.
3193
3194		CONFIG_SPL_TEXT_BASE
3195		TEXT_BASE for linking the SPL binary.
3196
3197		CONFIG_SPL_RELOC_TEXT_BASE
3198		Address to relocate to.  If unspecified, this is equal to
3199		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3200
3201		CONFIG_SPL_BSS_START_ADDR
3202		Link address for the BSS within the SPL binary.
3203
3204		CONFIG_SPL_BSS_MAX_SIZE
3205		Maximum size in memory allocated to the SPL BSS.
3206		When defined, the linker checks that the actual memory used
3207		by SPL from __bss_start to __bss_end does not exceed it.
3208		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3209		must not be both defined at the same time.
3210
3211		CONFIG_SPL_STACK
3212		Adress of the start of the stack SPL will use
3213
3214		CONFIG_SPL_RELOC_STACK
3215		Adress of the start of the stack SPL will use after
3216		relocation.  If unspecified, this is equal to
3217		CONFIG_SPL_STACK.
3218
3219		CONFIG_SYS_SPL_MALLOC_START
3220		Starting address of the malloc pool used in SPL.
3221
3222		CONFIG_SYS_SPL_MALLOC_SIZE
3223		The size of the malloc pool used in SPL.
3224
3225		CONFIG_SPL_FRAMEWORK
3226		Enable the SPL framework under common/.  This framework
3227		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3228		NAND loading of the Linux Kernel.
3229
3230		CONFIG_SPL_DISPLAY_PRINT
3231		For ARM, enable an optional function to print more information
3232		about the running system.
3233
3234		CONFIG_SPL_INIT_MINIMAL
3235		Arch init code should be built for a very small image
3236
3237		CONFIG_SPL_LIBCOMMON_SUPPORT
3238		Support for common/libcommon.o in SPL binary
3239
3240		CONFIG_SPL_LIBDISK_SUPPORT
3241		Support for disk/libdisk.o in SPL binary
3242
3243		CONFIG_SPL_I2C_SUPPORT
3244		Support for drivers/i2c/libi2c.o in SPL binary
3245
3246		CONFIG_SPL_GPIO_SUPPORT
3247		Support for drivers/gpio/libgpio.o in SPL binary
3248
3249		CONFIG_SPL_MMC_SUPPORT
3250		Support for drivers/mmc/libmmc.o in SPL binary
3251
3252		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3253		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3254		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
3255		Address, size and partition on the MMC to load U-Boot from
3256		when the MMC is being used in raw mode.
3257
3258		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3259		Sector to load kernel uImage from when MMC is being
3260		used in raw mode (for Falcon mode)
3261
3262		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3263		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3264		Sector and number of sectors to load kernel argument
3265		parameters from when MMC is being used in raw mode
3266		(for falcon mode)
3267
3268		CONFIG_SPL_FAT_SUPPORT
3269		Support for fs/fat/libfat.o in SPL binary
3270
3271		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
3272		Filename to read to load U-Boot when reading from FAT
3273
3274		CONFIG_SPL_FAT_LOAD_KERNEL_NAME
3275		Filename to read to load kernel uImage when reading
3276		from FAT (for Falcon mode)
3277
3278		CONFIG_SPL_FAT_LOAD_ARGS_NAME
3279		Filename to read to load kernel argument parameters
3280		when reading from FAT (for Falcon mode)
3281
3282		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3283		Set this for NAND SPL on PPC mpc83xx targets, so that
3284		start.S waits for the rest of the SPL to load before
3285		continuing (the hardware starts execution after just
3286		loading the first page rather than the full 4K).
3287
3288		CONFIG_SPL_NAND_BASE
3289		Include nand_base.c in the SPL.  Requires
3290		CONFIG_SPL_NAND_DRIVERS.
3291
3292		CONFIG_SPL_NAND_DRIVERS
3293		SPL uses normal NAND drivers, not minimal drivers.
3294
3295		CONFIG_SPL_NAND_ECC
3296		Include standard software ECC in the SPL
3297
3298		CONFIG_SPL_NAND_SIMPLE
3299		Support for NAND boot using simple NAND drivers that
3300		expose the cmd_ctrl() interface.
3301
3302		CONFIG_SPL_MPC8XXX_INIT_DDR_SUPPORT
3303		Set for the SPL on PPC mpc8xxx targets, support for
3304		drivers/ddr/fsl/libddr.o in SPL binary.
3305
3306		CONFIG_SPL_COMMON_INIT_DDR
3307		Set for common ddr init with serial presence detect in
3308		SPL binary.
3309
3310		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3311		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3312		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3313		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3314		CONFIG_SYS_NAND_ECCBYTES
3315		Defines the size and behavior of the NAND that SPL uses
3316		to read U-Boot
3317
3318		CONFIG_SPL_NAND_BOOT
3319		Add support NAND boot
3320
3321		CONFIG_SYS_NAND_U_BOOT_OFFS
3322		Location in NAND to read U-Boot from
3323
3324		CONFIG_SYS_NAND_U_BOOT_DST
3325		Location in memory to load U-Boot to
3326
3327		CONFIG_SYS_NAND_U_BOOT_SIZE
3328		Size of image to load
3329
3330		CONFIG_SYS_NAND_U_BOOT_START
3331		Entry point in loaded image to jump to
3332
3333		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3334		Define this if you need to first read the OOB and then the
3335		data. This is used for example on davinci plattforms.
3336
3337		CONFIG_SPL_OMAP3_ID_NAND
3338		Support for an OMAP3-specific set of functions to return the
3339		ID and MFR of the first attached NAND chip, if present.
3340
3341		CONFIG_SPL_SERIAL_SUPPORT
3342		Support for drivers/serial/libserial.o in SPL binary
3343
3344		CONFIG_SPL_SPI_FLASH_SUPPORT
3345		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
3346
3347		CONFIG_SPL_SPI_SUPPORT
3348		Support for drivers/spi/libspi.o in SPL binary
3349
3350		CONFIG_SPL_RAM_DEVICE
3351		Support for running image already present in ram, in SPL binary
3352
3353		CONFIG_SPL_LIBGENERIC_SUPPORT
3354		Support for lib/libgeneric.o in SPL binary
3355
3356		CONFIG_SPL_ENV_SUPPORT
3357		Support for the environment operating in SPL binary
3358
3359		CONFIG_SPL_NET_SUPPORT
3360		Support for the net/libnet.o in SPL binary.
3361		It conflicts with SPL env from storage medium specified by
3362		CONFIG_ENV_IS_xxx but CONFIG_ENV_IS_NOWHERE
3363
3364		CONFIG_SPL_PAD_TO
3365		Image offset to which the SPL should be padded before appending
3366		the SPL payload. By default, this is defined as
3367		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3368		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3369		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3370
3371		CONFIG_SPL_TARGET
3372		Final target image containing SPL and payload.  Some SPLs
3373		use an arch-specific makefile fragment instead, for
3374		example if more than one image needs to be produced.
3375
3376		CONFIG_FIT_SPL_PRINT
3377		Printing information about a FIT image adds quite a bit of
3378		code to SPL. So this is normally disabled in SPL. Use this
3379		option to re-enable it. This will affect the output of the
3380		bootm command when booting a FIT image.
3381
3382- TPL framework
3383		CONFIG_TPL
3384		Enable building of TPL globally.
3385
3386		CONFIG_TPL_PAD_TO
3387		Image offset to which the TPL should be padded before appending
3388		the TPL payload. By default, this is defined as
3389		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3390		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3391		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3392
3393Modem Support:
3394--------------
3395
3396[so far only for SMDK2400 boards]
3397
3398- Modem support enable:
3399		CONFIG_MODEM_SUPPORT
3400
3401- RTS/CTS Flow control enable:
3402		CONFIG_HWFLOW
3403
3404- Modem debug support:
3405		CONFIG_MODEM_SUPPORT_DEBUG
3406
3407		Enables debugging stuff (char screen[1024], dbg())
3408		for modem support. Useful only with BDI2000.
3409
3410- Interrupt support (PPC):
3411
3412		There are common interrupt_init() and timer_interrupt()
3413		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3414		for CPU specific initialization. interrupt_init_cpu()
3415		should set decrementer_count to appropriate value. If
3416		CPU resets decrementer automatically after interrupt
3417		(ppc4xx) it should set decrementer_count to zero.
3418		timer_interrupt() calls timer_interrupt_cpu() for CPU
3419		specific handling. If board has watchdog / status_led
3420		/ other_activity_monitor it works automatically from
3421		general timer_interrupt().
3422
3423- General:
3424
3425		In the target system modem support is enabled when a
3426		specific key (key combination) is pressed during
3427		power-on. Otherwise U-Boot will boot normally
3428		(autoboot). The key_pressed() function is called from
3429		board_init(). Currently key_pressed() is a dummy
3430		function, returning 1 and thus enabling modem
3431		initialization.
3432
3433		If there are no modem init strings in the
3434		environment, U-Boot proceed to autoboot; the
3435		previous output (banner, info printfs) will be
3436		suppressed, though.
3437
3438		See also: doc/README.Modem
3439
3440Board initialization settings:
3441------------------------------
3442
3443During Initialization u-boot calls a number of board specific functions
3444to allow the preparation of board specific prerequisites, e.g. pin setup
3445before drivers are initialized. To enable these callbacks the
3446following configuration macros have to be defined. Currently this is
3447architecture specific, so please check arch/your_architecture/lib/board.c
3448typically in board_init_f() and board_init_r().
3449
3450- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3451- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3452- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3453- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3454
3455Configuration Settings:
3456-----------------------
3457
3458- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3459		undefine this when you're short of memory.
3460
3461- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3462		width of the commands listed in the 'help' command output.
3463
3464- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3465		prompt for user input.
3466
3467- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3468
3469- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3470
3471- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3472
3473- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3474		the application (usually a Linux kernel) when it is
3475		booted
3476
3477- CONFIG_SYS_BAUDRATE_TABLE:
3478		List of legal baudrate settings for this board.
3479
3480- CONFIG_SYS_CONSOLE_INFO_QUIET
3481		Suppress display of console information at boot.
3482
3483- CONFIG_SYS_CONSOLE_IS_IN_ENV
3484		If the board specific function
3485			extern int overwrite_console (void);
3486		returns 1, the stdin, stderr and stdout are switched to the
3487		serial port, else the settings in the environment are used.
3488
3489- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3490		Enable the call to overwrite_console().
3491
3492- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3493		Enable overwrite of previous console environment settings.
3494
3495- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3496		Begin and End addresses of the area used by the
3497		simple memory test.
3498
3499- CONFIG_SYS_ALT_MEMTEST:
3500		Enable an alternate, more extensive memory test.
3501
3502- CONFIG_SYS_MEMTEST_SCRATCH:
3503		Scratch address used by the alternate memory test
3504		You only need to set this if address zero isn't writeable
3505
3506- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
3507		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3508		this specified memory area will get subtracted from the top
3509		(end) of RAM and won't get "touched" at all by U-Boot. By
3510		fixing up gd->ram_size the Linux kernel should gets passed
3511		the now "corrected" memory size and won't touch it either.
3512		This should work for arch/ppc and arch/powerpc. Only Linux
3513		board ports in arch/powerpc with bootwrapper support that
3514		recalculate the memory size from the SDRAM controller setup
3515		will have to get fixed in Linux additionally.
3516
3517		This option can be used as a workaround for the 440EPx/GRx
3518		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3519		be touched.
3520
3521		WARNING: Please make sure that this value is a multiple of
3522		the Linux page size (normally 4k). If this is not the case,
3523		then the end address of the Linux memory will be located at a
3524		non page size aligned address and this could cause major
3525		problems.
3526
3527- CONFIG_SYS_LOADS_BAUD_CHANGE:
3528		Enable temporary baudrate change while serial download
3529
3530- CONFIG_SYS_SDRAM_BASE:
3531		Physical start address of SDRAM. _Must_ be 0 here.
3532
3533- CONFIG_SYS_MBIO_BASE:
3534		Physical start address of Motherboard I/O (if using a
3535		Cogent motherboard)
3536
3537- CONFIG_SYS_FLASH_BASE:
3538		Physical start address of Flash memory.
3539
3540- CONFIG_SYS_MONITOR_BASE:
3541		Physical start address of boot monitor code (set by
3542		make config files to be same as the text base address
3543		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3544		CONFIG_SYS_FLASH_BASE when booting from flash.
3545
3546- CONFIG_SYS_MONITOR_LEN:
3547		Size of memory reserved for monitor code, used to
3548		determine _at_compile_time_ (!) if the environment is
3549		embedded within the U-Boot image, or in a separate
3550		flash sector.
3551
3552- CONFIG_SYS_MALLOC_LEN:
3553		Size of DRAM reserved for malloc() use.
3554
3555- CONFIG_SYS_BOOTM_LEN:
3556		Normally compressed uImages are limited to an
3557		uncompressed size of 8 MBytes. If this is not enough,
3558		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3559		to adjust this setting to your needs.
3560
3561- CONFIG_SYS_BOOTMAPSZ:
3562		Maximum size of memory mapped by the startup code of
3563		the Linux kernel; all data that must be processed by
3564		the Linux kernel (bd_info, boot arguments, FDT blob if
3565		used) must be put below this limit, unless "bootm_low"
3566		environment variable is defined and non-zero. In such case
3567		all data for the Linux kernel must be between "bootm_low"
3568		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3569		variable "bootm_mapsize" will override the value of
3570		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3571		then the value in "bootm_size" will be used instead.
3572
3573- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3574		Enable initrd_high functionality.  If defined then the
3575		initrd_high feature is enabled and the bootm ramdisk subcommand
3576		is enabled.
3577
3578- CONFIG_SYS_BOOT_GET_CMDLINE:
3579		Enables allocating and saving kernel cmdline in space between
3580		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3581
3582- CONFIG_SYS_BOOT_GET_KBD:
3583		Enables allocating and saving a kernel copy of the bd_info in
3584		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3585
3586- CONFIG_SYS_MAX_FLASH_BANKS:
3587		Max number of Flash memory banks
3588
3589- CONFIG_SYS_MAX_FLASH_SECT:
3590		Max number of sectors on a Flash chip
3591
3592- CONFIG_SYS_FLASH_ERASE_TOUT:
3593		Timeout for Flash erase operations (in ms)
3594
3595- CONFIG_SYS_FLASH_WRITE_TOUT:
3596		Timeout for Flash write operations (in ms)
3597
3598- CONFIG_SYS_FLASH_LOCK_TOUT
3599		Timeout for Flash set sector lock bit operation (in ms)
3600
3601- CONFIG_SYS_FLASH_UNLOCK_TOUT
3602		Timeout for Flash clear lock bits operation (in ms)
3603
3604- CONFIG_SYS_FLASH_PROTECTION
3605		If defined, hardware flash sectors protection is used
3606		instead of U-Boot software protection.
3607
3608- CONFIG_SYS_DIRECT_FLASH_TFTP:
3609
3610		Enable TFTP transfers directly to flash memory;
3611		without this option such a download has to be
3612		performed in two steps: (1) download to RAM, and (2)
3613		copy from RAM to flash.
3614
3615		The two-step approach is usually more reliable, since
3616		you can check if the download worked before you erase
3617		the flash, but in some situations (when system RAM is
3618		too limited to allow for a temporary copy of the
3619		downloaded image) this option may be very useful.
3620
3621- CONFIG_SYS_FLASH_CFI:
3622		Define if the flash driver uses extra elements in the
3623		common flash structure for storing flash geometry.
3624
3625- CONFIG_FLASH_CFI_DRIVER
3626		This option also enables the building of the cfi_flash driver
3627		in the drivers directory
3628
3629- CONFIG_FLASH_CFI_MTD
3630		This option enables the building of the cfi_mtd driver
3631		in the drivers directory. The driver exports CFI flash
3632		to the MTD layer.
3633
3634- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3635		Use buffered writes to flash.
3636
3637- CONFIG_FLASH_SPANSION_S29WS_N
3638		s29ws-n MirrorBit flash has non-standard addresses for buffered
3639		write commands.
3640
3641- CONFIG_SYS_FLASH_QUIET_TEST
3642		If this option is defined, the common CFI flash doesn't
3643		print it's warning upon not recognized FLASH banks. This
3644		is useful, if some of the configured banks are only
3645		optionally available.
3646
3647- CONFIG_FLASH_SHOW_PROGRESS
3648		If defined (must be an integer), print out countdown
3649		digits and dots.  Recommended value: 45 (9..1) for 80
3650		column displays, 15 (3..1) for 40 column displays.
3651
3652- CONFIG_FLASH_VERIFY
3653		If defined, the content of the flash (destination) is compared
3654		against the source after the write operation. An error message
3655		will be printed when the contents are not identical.
3656		Please note that this option is useless in nearly all cases,
3657		since such flash programming errors usually are detected earlier
3658		while unprotecting/erasing/programming. Please only enable
3659		this option if you really know what you are doing.
3660
3661- CONFIG_SYS_RX_ETH_BUFFER:
3662		Defines the number of Ethernet receive buffers. On some
3663		Ethernet controllers it is recommended to set this value
3664		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3665		buffers can be full shortly after enabling the interface
3666		on high Ethernet traffic.
3667		Defaults to 4 if not defined.
3668
3669- CONFIG_ENV_MAX_ENTRIES
3670
3671	Maximum number of entries in the hash table that is used
3672	internally to store the environment settings. The default
3673	setting is supposed to be generous and should work in most
3674	cases. This setting can be used to tune behaviour; see
3675	lib/hashtable.c for details.
3676
3677- CONFIG_ENV_FLAGS_LIST_DEFAULT
3678- CONFIG_ENV_FLAGS_LIST_STATIC
3679	Enable validation of the values given to environment variables when
3680	calling env set.  Variables can be restricted to only decimal,
3681	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3682	the variables can also be restricted to IP address or MAC address.
3683
3684	The format of the list is:
3685		type_attribute = [s|d|x|b|i|m]
3686		access_atribute = [a|r|o|c]
3687		attributes = type_attribute[access_atribute]
3688		entry = variable_name[:attributes]
3689		list = entry[,list]
3690
3691	The type attributes are:
3692		s - String (default)
3693		d - Decimal
3694		x - Hexadecimal
3695		b - Boolean ([1yYtT|0nNfF])
3696		i - IP address
3697		m - MAC address
3698
3699	The access attributes are:
3700		a - Any (default)
3701		r - Read-only
3702		o - Write-once
3703		c - Change-default
3704
3705	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3706		Define this to a list (string) to define the ".flags"
3707		envirnoment variable in the default or embedded environment.
3708
3709	- CONFIG_ENV_FLAGS_LIST_STATIC
3710		Define this to a list (string) to define validation that
3711		should be done if an entry is not found in the ".flags"
3712		environment variable.  To override a setting in the static
3713		list, simply add an entry for the same variable name to the
3714		".flags" variable.
3715
3716- CONFIG_ENV_ACCESS_IGNORE_FORCE
3717	If defined, don't allow the -f switch to env set override variable
3718	access flags.
3719
3720- CONFIG_SYS_GENERIC_BOARD
3721	This selects the architecture-generic board system instead of the
3722	architecture-specific board files. It is intended to move boards
3723	to this new framework over time. Defining this will disable the
3724	arch/foo/lib/board.c file and use common/board_f.c and
3725	common/board_r.c instead. To use this option your architecture
3726	must support it (i.e. must define __HAVE_ARCH_GENERIC_BOARD in
3727	its config.mk file). If you find problems enabling this option on
3728	your board please report the problem and send patches!
3729
3730- CONFIG_SYS_SYM_OFFSETS
3731	This is set by architectures that use offsets for link symbols
3732	instead of absolute values. So bss_start is obtained using an
3733	offset _bss_start_ofs from CONFIG_SYS_TEXT_BASE, rather than
3734	directly. You should not need to touch this setting.
3735
3736- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
3737	This is set by OMAP boards for the max time that reset should
3738	be asserted. See doc/README.omap-reset-time for details on how
3739	the value can be calulated on a given board.
3740
3741The following definitions that deal with the placement and management
3742of environment data (variable area); in general, we support the
3743following configurations:
3744
3745- CONFIG_BUILD_ENVCRC:
3746
3747	Builds up envcrc with the target environment so that external utils
3748	may easily extract it and embed it in final U-Boot images.
3749
3750- CONFIG_ENV_IS_IN_FLASH:
3751
3752	Define this if the environment is in flash memory.
3753
3754	a) The environment occupies one whole flash sector, which is
3755	   "embedded" in the text segment with the U-Boot code. This
3756	   happens usually with "bottom boot sector" or "top boot
3757	   sector" type flash chips, which have several smaller
3758	   sectors at the start or the end. For instance, such a
3759	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3760	   such a case you would place the environment in one of the
3761	   4 kB sectors - with U-Boot code before and after it. With
3762	   "top boot sector" type flash chips, you would put the
3763	   environment in one of the last sectors, leaving a gap
3764	   between U-Boot and the environment.
3765
3766	- CONFIG_ENV_OFFSET:
3767
3768	   Offset of environment data (variable area) to the
3769	   beginning of flash memory; for instance, with bottom boot
3770	   type flash chips the second sector can be used: the offset
3771	   for this sector is given here.
3772
3773	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3774
3775	- CONFIG_ENV_ADDR:
3776
3777	   This is just another way to specify the start address of
3778	   the flash sector containing the environment (instead of
3779	   CONFIG_ENV_OFFSET).
3780
3781	- CONFIG_ENV_SECT_SIZE:
3782
3783	   Size of the sector containing the environment.
3784
3785
3786	b) Sometimes flash chips have few, equal sized, BIG sectors.
3787	   In such a case you don't want to spend a whole sector for
3788	   the environment.
3789
3790	- CONFIG_ENV_SIZE:
3791
3792	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3793	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3794	   of this flash sector for the environment. This saves
3795	   memory for the RAM copy of the environment.
3796
3797	   It may also save flash memory if you decide to use this
3798	   when your environment is "embedded" within U-Boot code,
3799	   since then the remainder of the flash sector could be used
3800	   for U-Boot code. It should be pointed out that this is
3801	   STRONGLY DISCOURAGED from a robustness point of view:
3802	   updating the environment in flash makes it always
3803	   necessary to erase the WHOLE sector. If something goes
3804	   wrong before the contents has been restored from a copy in
3805	   RAM, your target system will be dead.
3806
3807	- CONFIG_ENV_ADDR_REDUND
3808	  CONFIG_ENV_SIZE_REDUND
3809
3810	   These settings describe a second storage area used to hold
3811	   a redundant copy of the environment data, so that there is
3812	   a valid backup copy in case there is a power failure during
3813	   a "saveenv" operation.
3814
3815BE CAREFUL! Any changes to the flash layout, and some changes to the
3816source code will make it necessary to adapt <board>/u-boot.lds*
3817accordingly!
3818
3819
3820- CONFIG_ENV_IS_IN_NVRAM:
3821
3822	Define this if you have some non-volatile memory device
3823	(NVRAM, battery buffered SRAM) which you want to use for the
3824	environment.
3825
3826	- CONFIG_ENV_ADDR:
3827	- CONFIG_ENV_SIZE:
3828
3829	  These two #defines are used to determine the memory area you
3830	  want to use for environment. It is assumed that this memory
3831	  can just be read and written to, without any special
3832	  provision.
3833
3834BE CAREFUL! The first access to the environment happens quite early
3835in U-Boot initalization (when we try to get the setting of for the
3836console baudrate). You *MUST* have mapped your NVRAM area then, or
3837U-Boot will hang.
3838
3839Please note that even with NVRAM we still use a copy of the
3840environment in RAM: we could work on NVRAM directly, but we want to
3841keep settings there always unmodified except somebody uses "saveenv"
3842to save the current settings.
3843
3844
3845- CONFIG_ENV_IS_IN_EEPROM:
3846
3847	Use this if you have an EEPROM or similar serial access
3848	device and a driver for it.
3849
3850	- CONFIG_ENV_OFFSET:
3851	- CONFIG_ENV_SIZE:
3852
3853	  These two #defines specify the offset and size of the
3854	  environment area within the total memory of your EEPROM.
3855
3856	- CONFIG_SYS_I2C_EEPROM_ADDR:
3857	  If defined, specified the chip address of the EEPROM device.
3858	  The default address is zero.
3859
3860	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3861	  If defined, the number of bits used to address bytes in a
3862	  single page in the EEPROM device.  A 64 byte page, for example
3863	  would require six bits.
3864
3865	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3866	  If defined, the number of milliseconds to delay between
3867	  page writes.	The default is zero milliseconds.
3868
3869	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3870	  The length in bytes of the EEPROM memory array address.  Note
3871	  that this is NOT the chip address length!
3872
3873	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3874	  EEPROM chips that implement "address overflow" are ones
3875	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3876	  address and the extra bits end up in the "chip address" bit
3877	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3878	  byte chips.
3879
3880	  Note that we consider the length of the address field to
3881	  still be one byte because the extra address bits are hidden
3882	  in the chip address.
3883
3884	- CONFIG_SYS_EEPROM_SIZE:
3885	  The size in bytes of the EEPROM device.
3886
3887	- CONFIG_ENV_EEPROM_IS_ON_I2C
3888	  define this, if you have I2C and SPI activated, and your
3889	  EEPROM, which holds the environment, is on the I2C bus.
3890
3891	- CONFIG_I2C_ENV_EEPROM_BUS
3892	  if you have an Environment on an EEPROM reached over
3893	  I2C muxes, you can define here, how to reach this
3894	  EEPROM. For example:
3895
3896	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
3897
3898	  EEPROM which holds the environment, is reached over
3899	  a pca9547 i2c mux with address 0x70, channel 3.
3900
3901- CONFIG_ENV_IS_IN_DATAFLASH:
3902
3903	Define this if you have a DataFlash memory device which you
3904	want to use for the environment.
3905
3906	- CONFIG_ENV_OFFSET:
3907	- CONFIG_ENV_ADDR:
3908	- CONFIG_ENV_SIZE:
3909
3910	  These three #defines specify the offset and size of the
3911	  environment area within the total memory of your DataFlash placed
3912	  at the specified address.
3913
3914- CONFIG_ENV_IS_IN_REMOTE:
3915
3916	Define this if you have a remote memory space which you
3917	want to use for the local device's environment.
3918
3919	- CONFIG_ENV_ADDR:
3920	- CONFIG_ENV_SIZE:
3921
3922	  These two #defines specify the address and size of the
3923	  environment area within the remote memory space. The
3924	  local device can get the environment from remote memory
3925	  space by SRIO or PCIE links.
3926
3927BE CAREFUL! For some special cases, the local device can not use
3928"saveenv" command. For example, the local device will get the
3929environment stored in a remote NOR flash by SRIO or PCIE link,
3930but it can not erase, write this NOR flash by SRIO or PCIE interface.
3931
3932- CONFIG_ENV_IS_IN_NAND:
3933
3934	Define this if you have a NAND device which you want to use
3935	for the environment.
3936
3937	- CONFIG_ENV_OFFSET:
3938	- CONFIG_ENV_SIZE:
3939
3940	  These two #defines specify the offset and size of the environment
3941	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
3942	  aligned to an erase block boundary.
3943
3944	- CONFIG_ENV_OFFSET_REDUND (optional):
3945
3946	  This setting describes a second storage area of CONFIG_ENV_SIZE
3947	  size used to hold a redundant copy of the environment data, so
3948	  that there is a valid backup copy in case there is a power failure
3949	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
3950	  aligned to an erase block boundary.
3951
3952	- CONFIG_ENV_RANGE (optional):
3953
3954	  Specifies the length of the region in which the environment
3955	  can be written.  This should be a multiple of the NAND device's
3956	  block size.  Specifying a range with more erase blocks than
3957	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
3958	  the range to be avoided.
3959
3960	- CONFIG_ENV_OFFSET_OOB (optional):
3961
3962	  Enables support for dynamically retrieving the offset of the
3963	  environment from block zero's out-of-band data.  The
3964	  "nand env.oob" command can be used to record this offset.
3965	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
3966	  using CONFIG_ENV_OFFSET_OOB.
3967
3968- CONFIG_NAND_ENV_DST
3969
3970	Defines address in RAM to which the nand_spl code should copy the
3971	environment. If redundant environment is used, it will be copied to
3972	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3973
3974- CONFIG_ENV_IS_IN_UBI:
3975
3976	Define this if you have an UBI volume that you want to use for the
3977	environment.  This has the benefit of wear-leveling the environment
3978	accesses, which is important on NAND.
3979
3980	- CONFIG_ENV_UBI_PART:
3981
3982	  Define this to a string that is the mtd partition containing the UBI.
3983
3984	- CONFIG_ENV_UBI_VOLUME:
3985
3986	  Define this to the name of the volume that you want to store the
3987	  environment in.
3988
3989	- CONFIG_ENV_UBI_VOLUME_REDUND:
3990
3991	  Define this to the name of another volume to store a second copy of
3992	  the environment in.  This will enable redundant environments in UBI.
3993	  It is assumed that both volumes are in the same MTD partition.
3994
3995	- CONFIG_UBI_SILENCE_MSG
3996	- CONFIG_UBIFS_SILENCE_MSG
3997
3998	  You will probably want to define these to avoid a really noisy system
3999	  when storing the env in UBI.
4000
4001- CONFIG_ENV_IS_IN_MMC:
4002
4003	Define this if you have an MMC device which you want to use for the
4004	environment.
4005
4006	- CONFIG_SYS_MMC_ENV_DEV:
4007
4008	  Specifies which MMC device the environment is stored in.
4009
4010	- CONFIG_SYS_MMC_ENV_PART (optional):
4011
4012	  Specifies which MMC partition the environment is stored in. If not
4013	  set, defaults to partition 0, the user area. Common values might be
4014	  1 (first MMC boot partition), 2 (second MMC boot partition).
4015
4016	- CONFIG_ENV_OFFSET:
4017	- CONFIG_ENV_SIZE:
4018
4019	  These two #defines specify the offset and size of the environment
4020	  area within the specified MMC device.
4021
4022	  If offset is positive (the usual case), it is treated as relative to
4023	  the start of the MMC partition. If offset is negative, it is treated
4024	  as relative to the end of the MMC partition. This can be useful if
4025	  your board may be fitted with different MMC devices, which have
4026	  different sizes for the MMC partitions, and you always want the
4027	  environment placed at the very end of the partition, to leave the
4028	  maximum possible space before it, to store other data.
4029
4030	  These two values are in units of bytes, but must be aligned to an
4031	  MMC sector boundary.
4032
4033	- CONFIG_ENV_OFFSET_REDUND (optional):
4034
4035	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
4036	  hold a redundant copy of the environment data. This provides a
4037	  valid backup copy in case the other copy is corrupted, e.g. due
4038	  to a power failure during a "saveenv" operation.
4039
4040	  This value may also be positive or negative; this is handled in the
4041	  same way as CONFIG_ENV_OFFSET.
4042
4043	  This value is also in units of bytes, but must also be aligned to
4044	  an MMC sector boundary.
4045
4046	- CONFIG_ENV_SIZE_REDUND (optional):
4047
4048	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
4049	  set. If this value is set, it must be set to the same value as
4050	  CONFIG_ENV_SIZE.
4051
4052- CONFIG_SYS_SPI_INIT_OFFSET
4053
4054	Defines offset to the initial SPI buffer area in DPRAM. The
4055	area is used at an early stage (ROM part) if the environment
4056	is configured to reside in the SPI EEPROM: We need a 520 byte
4057	scratch DPRAM area. It is used between the two initialization
4058	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
4059	to be a good choice since it makes it far enough from the
4060	start of the data area as well as from the stack pointer.
4061
4062Please note that the environment is read-only until the monitor
4063has been relocated to RAM and a RAM copy of the environment has been
4064created; also, when using EEPROM you will have to use getenv_f()
4065until then to read environment variables.
4066
4067The environment is protected by a CRC32 checksum. Before the monitor
4068is relocated into RAM, as a result of a bad CRC you will be working
4069with the compiled-in default environment - *silently*!!! [This is
4070necessary, because the first environment variable we need is the
4071"baudrate" setting for the console - if we have a bad CRC, we don't
4072have any device yet where we could complain.]
4073
4074Note: once the monitor has been relocated, then it will complain if
4075the default environment is used; a new CRC is computed as soon as you
4076use the "saveenv" command to store a valid environment.
4077
4078- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
4079		Echo the inverted Ethernet link state to the fault LED.
4080
4081		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
4082		      also needs to be defined.
4083
4084- CONFIG_SYS_FAULT_MII_ADDR:
4085		MII address of the PHY to check for the Ethernet link state.
4086
4087- CONFIG_NS16550_MIN_FUNCTIONS:
4088		Define this if you desire to only have use of the NS16550_init
4089		and NS16550_putc functions for the serial driver located at
4090		drivers/serial/ns16550.c.  This option is useful for saving
4091		space for already greatly restricted images, including but not
4092		limited to NAND_SPL configurations.
4093
4094- CONFIG_DISPLAY_BOARDINFO
4095		Display information about the board that U-Boot is running on
4096		when U-Boot starts up. The board function checkboard() is called
4097		to do this.
4098
4099- CONFIG_DISPLAY_BOARDINFO_LATE
4100		Similar to the previous option, but display this information
4101		later, once stdio is running and output goes to the LCD, if
4102		present.
4103
4104Low Level (hardware related) configuration options:
4105---------------------------------------------------
4106
4107- CONFIG_SYS_CACHELINE_SIZE:
4108		Cache Line Size of the CPU.
4109
4110- CONFIG_SYS_DEFAULT_IMMR:
4111		Default address of the IMMR after system reset.
4112
4113		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4114		and RPXsuper) to be able to adjust the position of
4115		the IMMR register after a reset.
4116
4117- CONFIG_SYS_CCSRBAR_DEFAULT:
4118		Default (power-on reset) physical address of CCSR on Freescale
4119		PowerPC SOCs.
4120
4121- CONFIG_SYS_CCSRBAR:
4122		Virtual address of CCSR.  On a 32-bit build, this is typically
4123		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4124
4125		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4126		for cross-platform code that uses that macro instead.
4127
4128- CONFIG_SYS_CCSRBAR_PHYS:
4129		Physical address of CCSR.  CCSR can be relocated to a new
4130		physical address, if desired.  In this case, this macro should
4131		be set to that address.	 Otherwise, it should be set to the
4132		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
4133		is typically relocated on 36-bit builds.  It is recommended
4134		that this macro be defined via the _HIGH and _LOW macros:
4135
4136		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4137			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4138
4139- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4140		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
4141		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
4142		used in assembly code, so it must not contain typecasts or
4143		integer size suffixes (e.g. "ULL").
4144
4145- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4146		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  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_CCSR_DO_NOT_RELOCATE:
4151		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4152		forced to a value that ensures that CCSR is not relocated.
4153
4154- Floppy Disk Support:
4155		CONFIG_SYS_FDC_DRIVE_NUMBER
4156
4157		the default drive number (default value 0)
4158
4159		CONFIG_SYS_ISA_IO_STRIDE
4160
4161		defines the spacing between FDC chipset registers
4162		(default value 1)
4163
4164		CONFIG_SYS_ISA_IO_OFFSET
4165
4166		defines the offset of register from address. It
4167		depends on which part of the data bus is connected to
4168		the FDC chipset. (default value 0)
4169
4170		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4171		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4172		default value.
4173
4174		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4175		fdc_hw_init() is called at the beginning of the FDC
4176		setup. fdc_hw_init() must be provided by the board
4177		source code. It is used to make hardware dependant
4178		initializations.
4179
4180- CONFIG_IDE_AHB:
4181		Most IDE controllers were designed to be connected with PCI
4182		interface. Only few of them were designed for AHB interface.
4183		When software is doing ATA command and data transfer to
4184		IDE devices through IDE-AHB controller, some additional
4185		registers accessing to these kind of IDE-AHB controller
4186		is requierd.
4187
4188- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4189		DO NOT CHANGE unless you know exactly what you're
4190		doing! (11-4) [MPC8xx/82xx systems only]
4191
4192- CONFIG_SYS_INIT_RAM_ADDR:
4193
4194		Start address of memory area that can be used for
4195		initial data and stack; please note that this must be
4196		writable memory that is working WITHOUT special
4197		initialization, i. e. you CANNOT use normal RAM which
4198		will become available only after programming the
4199		memory controller and running certain initialization
4200		sequences.
4201
4202		U-Boot uses the following memory types:
4203		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4204		- MPC824X: data cache
4205		- PPC4xx:  data cache
4206
4207- CONFIG_SYS_GBL_DATA_OFFSET:
4208
4209		Offset of the initial data structure in the memory
4210		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4211		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4212		data is located at the end of the available space
4213		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4214		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
4215		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4216		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4217
4218	Note:
4219		On the MPC824X (or other systems that use the data
4220		cache for initial memory) the address chosen for
4221		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4222		point to an otherwise UNUSED address space between
4223		the top of RAM and the start of the PCI space.
4224
4225- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4226
4227- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4228
4229- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4230
4231- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4232
4233- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4234
4235- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4236
4237- CONFIG_SYS_OR_TIMING_SDRAM:
4238		SDRAM timing
4239
4240- CONFIG_SYS_MAMR_PTA:
4241		periodic timer for refresh
4242
4243- CONFIG_SYS_DER:	Debug Event Register (37-47)
4244
4245- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4246  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4247  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4248  CONFIG_SYS_BR1_PRELIM:
4249		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4250
4251- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4252  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4253  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4254		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4255
4256- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4257  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4258		Machine Mode Register and Memory Periodic Timer
4259		Prescaler definitions (SDRAM timing)
4260
4261- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4262		enable I2C microcode relocation patch (MPC8xx);
4263		define relocation offset in DPRAM [DSP2]
4264
4265- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4266		enable SMC microcode relocation patch (MPC8xx);
4267		define relocation offset in DPRAM [SMC1]
4268
4269- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4270		enable SPI microcode relocation patch (MPC8xx);
4271		define relocation offset in DPRAM [SCC4]
4272
4273- CONFIG_SYS_USE_OSCCLK:
4274		Use OSCM clock mode on MBX8xx board. Be careful,
4275		wrong setting might damage your board. Read
4276		doc/README.MBX before setting this variable!
4277
4278- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4279		Offset of the bootmode word in DPRAM used by post
4280		(Power On Self Tests). This definition overrides
4281		#define'd default value in commproc.h resp.
4282		cpm_8260.h.
4283
4284- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4285  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4286  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4287  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4288  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4289  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4290  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4291  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4292		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4293
4294- CONFIG_PCI_DISABLE_PCIE:
4295		Disable PCI-Express on systems where it is supported but not
4296		required.
4297
4298- CONFIG_PCI_ENUM_ONLY
4299		Only scan through and get the devices on the busses.
4300		Don't do any setup work, presumably because someone or
4301		something has already done it, and we don't need to do it
4302		a second time.	Useful for platforms that are pre-booted
4303		by coreboot or similar.
4304
4305- CONFIG_PCI_INDIRECT_BRIDGE:
4306		Enable support for indirect PCI bridges.
4307
4308- CONFIG_SYS_SRIO:
4309		Chip has SRIO or not
4310
4311- CONFIG_SRIO1:
4312		Board has SRIO 1 port available
4313
4314- CONFIG_SRIO2:
4315		Board has SRIO 2 port available
4316
4317- CONFIG_SRIO_PCIE_BOOT_MASTER
4318		Board can support master function for Boot from SRIO and PCIE
4319
4320- CONFIG_SYS_SRIOn_MEM_VIRT:
4321		Virtual Address of SRIO port 'n' memory region
4322
4323- CONFIG_SYS_SRIOn_MEM_PHYS:
4324		Physical Address of SRIO port 'n' memory region
4325
4326- CONFIG_SYS_SRIOn_MEM_SIZE:
4327		Size of SRIO port 'n' memory region
4328
4329- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4330		Defined to tell the NAND controller that the NAND chip is using
4331		a 16 bit bus.
4332		Not all NAND drivers use this symbol.
4333		Example of drivers that use it:
4334		- drivers/mtd/nand/ndfc.c
4335		- drivers/mtd/nand/mxc_nand.c
4336
4337- CONFIG_SYS_NDFC_EBC0_CFG
4338		Sets the EBC0_CFG register for the NDFC. If not defined
4339		a default value will be used.
4340
4341- CONFIG_SPD_EEPROM
4342		Get DDR timing information from an I2C EEPROM. Common
4343		with pluggable memory modules such as SODIMMs
4344
4345  SPD_EEPROM_ADDRESS
4346		I2C address of the SPD EEPROM
4347
4348- CONFIG_SYS_SPD_BUS_NUM
4349		If SPD EEPROM is on an I2C bus other than the first
4350		one, specify here. Note that the value must resolve
4351		to something your driver can deal with.
4352
4353- CONFIG_SYS_DDR_RAW_TIMING
4354		Get DDR timing information from other than SPD. Common with
4355		soldered DDR chips onboard without SPD. DDR raw timing
4356		parameters are extracted from datasheet and hard-coded into
4357		header files or board specific files.
4358
4359- CONFIG_FSL_DDR_INTERACTIVE
4360		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4361
4362- CONFIG_SYS_83XX_DDR_USES_CS0
4363		Only for 83xx systems. If specified, then DDR should
4364		be configured using CS0 and CS1 instead of CS2 and CS3.
4365
4366- CONFIG_ETHER_ON_FEC[12]
4367		Define to enable FEC[12] on a 8xx series processor.
4368
4369- CONFIG_FEC[12]_PHY
4370		Define to the hardcoded PHY address which corresponds
4371		to the given FEC; i. e.
4372			#define CONFIG_FEC1_PHY 4
4373		means that the PHY with address 4 is connected to FEC1
4374
4375		When set to -1, means to probe for first available.
4376
4377- CONFIG_FEC[12]_PHY_NORXERR
4378		The PHY does not have a RXERR line (RMII only).
4379		(so program the FEC to ignore it).
4380
4381- CONFIG_RMII
4382		Enable RMII mode for all FECs.
4383		Note that this is a global option, we can't
4384		have one FEC in standard MII mode and another in RMII mode.
4385
4386- CONFIG_CRC32_VERIFY
4387		Add a verify option to the crc32 command.
4388		The syntax is:
4389
4390		=> crc32 -v <address> <count> <crc32>
4391
4392		Where address/count indicate a memory area
4393		and crc32 is the correct crc32 which the
4394		area should have.
4395
4396- CONFIG_LOOPW
4397		Add the "loopw" memory command. This only takes effect if
4398		the memory commands are activated globally (CONFIG_CMD_MEM).
4399
4400- CONFIG_MX_CYCLIC
4401		Add the "mdc" and "mwc" memory commands. These are cyclic
4402		"md/mw" commands.
4403		Examples:
4404
4405		=> mdc.b 10 4 500
4406		This command will print 4 bytes (10,11,12,13) each 500 ms.
4407
4408		=> mwc.l 100 12345678 10
4409		This command will write 12345678 to address 100 all 10 ms.
4410
4411		This only takes effect if the memory commands are activated
4412		globally (CONFIG_CMD_MEM).
4413
4414- CONFIG_SKIP_LOWLEVEL_INIT
4415		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4416		low level initializations (like setting up the memory
4417		controller) are omitted and/or U-Boot does not
4418		relocate itself into RAM.
4419
4420		Normally this variable MUST NOT be defined. The only
4421		exception is when U-Boot is loaded (to RAM) by some
4422		other boot loader or by a debugger which performs
4423		these initializations itself.
4424
4425- CONFIG_SPL_BUILD
4426		Modifies the behaviour of start.S when compiling a loader
4427		that is executed before the actual U-Boot. E.g. when
4428		compiling a NAND SPL.
4429
4430- CONFIG_TPL_BUILD
4431		Modifies the behaviour of start.S  when compiling a loader
4432		that is executed after the SPL and before the actual U-Boot.
4433		It is loaded by the SPL.
4434
4435- CONFIG_SYS_MPC85XX_NO_RESETVEC
4436		Only for 85xx systems. If this variable is specified, the section
4437		.resetvec is not kept and the section .bootpg is placed in the
4438		previous 4k of the .text section.
4439
4440- CONFIG_ARCH_MAP_SYSMEM
4441		Generally U-Boot (and in particular the md command) uses
4442		effective address. It is therefore not necessary to regard
4443		U-Boot address as virtual addresses that need to be translated
4444		to physical addresses. However, sandbox requires this, since
4445		it maintains its own little RAM buffer which contains all
4446		addressable memory. This option causes some memory accesses
4447		to be mapped through map_sysmem() / unmap_sysmem().
4448
4449- CONFIG_USE_ARCH_MEMCPY
4450  CONFIG_USE_ARCH_MEMSET
4451		If these options are used a optimized version of memcpy/memset will
4452		be used if available. These functions may be faster under some
4453		conditions but may increase the binary size.
4454
4455- CONFIG_X86_RESET_VECTOR
4456		If defined, the x86 reset vector code is included. This is not
4457		needed when U-Boot is running from Coreboot.
4458
4459- CONFIG_SYS_MPUCLK
4460		Defines the MPU clock speed (in MHz).
4461
4462		NOTE : currently only supported on AM335x platforms.
4463
4464- CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
4465		Enables the RTC32K OSC on AM33xx based plattforms
4466
4467Freescale QE/FMAN Firmware Support:
4468-----------------------------------
4469
4470The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4471loading of "firmware", which is encoded in the QE firmware binary format.
4472This firmware often needs to be loaded during U-Boot booting, so macros
4473are used to identify the storage device (NOR flash, SPI, etc) and the address
4474within that device.
4475
4476- CONFIG_SYS_QE_FMAN_FW_ADDR
4477	The address in the storage device where the firmware is located.  The
4478	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4479	is also specified.
4480
4481- CONFIG_SYS_QE_FMAN_FW_LENGTH
4482	The maximum possible size of the firmware.  The firmware binary format
4483	has a field that specifies the actual size of the firmware, but it
4484	might not be possible to read any part of the firmware unless some
4485	local storage is allocated to hold the entire firmware first.
4486
4487- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4488	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4489	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4490	virtual address in NOR flash.
4491
4492- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4493	Specifies that QE/FMAN firmware is located in NAND flash.
4494	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4495
4496- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4497	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4498	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4499
4500- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
4501	Specifies that QE/FMAN firmware is located on the primary SPI
4502	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4503
4504- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4505	Specifies that QE/FMAN firmware is located in the remote (master)
4506	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4507	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4508	window->master inbound window->master LAW->the ucode address in
4509	master's memory space.
4510
4511Building the Software:
4512======================
4513
4514Building U-Boot has been tested in several native build environments
4515and in many different cross environments. Of course we cannot support
4516all possibly existing versions of cross development tools in all
4517(potentially obsolete) versions. In case of tool chain problems we
4518recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4519which is extensively used to build and test U-Boot.
4520
4521If you are not using a native environment, it is assumed that you
4522have GNU cross compiling tools available in your path. In this case,
4523you must set the environment variable CROSS_COMPILE in your shell.
4524Note that no changes to the Makefile or any other source files are
4525necessary. For example using the ELDK on a 4xx CPU, please enter:
4526
4527	$ CROSS_COMPILE=ppc_4xx-
4528	$ export CROSS_COMPILE
4529
4530Note: If you wish to generate Windows versions of the utilities in
4531      the tools directory you can use the MinGW toolchain
4532      (http://www.mingw.org).  Set your HOST tools to the MinGW
4533      toolchain and execute 'make tools'.  For example:
4534
4535       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4536
4537      Binaries such as tools/mkimage.exe will be created which can
4538      be executed on computers running Windows.
4539
4540U-Boot is intended to be simple to build. After installing the
4541sources you must configure U-Boot for one specific board type. This
4542is done by typing:
4543
4544	make NAME_config
4545
4546where "NAME_config" is the name of one of the existing configu-
4547rations; see boards.cfg for supported names.
4548
4549Note: for some board special configuration names may exist; check if
4550      additional information is available from the board vendor; for
4551      instance, the TQM823L systems are available without (standard)
4552      or with LCD support. You can select such additional "features"
4553      when choosing the configuration, i. e.
4554
4555      make TQM823L_config
4556	- will configure for a plain TQM823L, i. e. no LCD support
4557
4558      make TQM823L_LCD_config
4559	- will configure for a TQM823L with U-Boot console on LCD
4560
4561      etc.
4562
4563
4564Finally, type "make all", and you should get some working U-Boot
4565images ready for download to / installation on your system:
4566
4567- "u-boot.bin" is a raw binary image
4568- "u-boot" is an image in ELF binary format
4569- "u-boot.srec" is in Motorola S-Record format
4570
4571By default the build is performed locally and the objects are saved
4572in the source directory. One of the two methods can be used to change
4573this behavior and build U-Boot to some external directory:
4574
45751. Add O= to the make command line invocations:
4576
4577	make O=/tmp/build distclean
4578	make O=/tmp/build NAME_config
4579	make O=/tmp/build all
4580
45812. Set environment variable BUILD_DIR to point to the desired location:
4582
4583	export BUILD_DIR=/tmp/build
4584	make distclean
4585	make NAME_config
4586	make all
4587
4588Note that the command line "O=" setting overrides the BUILD_DIR environment
4589variable.
4590
4591
4592Please be aware that the Makefiles assume you are using GNU make, so
4593for instance on NetBSD you might need to use "gmake" instead of
4594native "make".
4595
4596
4597If the system board that you have is not listed, then you will need
4598to port U-Boot to your hardware platform. To do this, follow these
4599steps:
4600
46011.  Add a new configuration option for your board to the toplevel
4602    "boards.cfg" file, using the existing entries as examples.
4603    Follow the instructions there to keep the boards in order.
46042.  Create a new directory to hold your board specific code. Add any
4605    files you need. In your board directory, you will need at least
4606    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
46073.  Create a new configuration file "include/configs/<board>.h" for
4608    your board
46093.  If you're porting U-Boot to a new CPU, then also create a new
4610    directory to hold your CPU specific code. Add any files you need.
46114.  Run "make <board>_config" with your new name.
46125.  Type "make", and you should get a working "u-boot.srec" file
4613    to be installed on your target system.
46146.  Debug and solve any problems that might arise.
4615    [Of course, this last step is much harder than it sounds.]
4616
4617
4618Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4619==============================================================
4620
4621If you have modified U-Boot sources (for instance added a new board
4622or support for new devices, a new CPU, etc.) you are expected to
4623provide feedback to the other developers. The feedback normally takes
4624the form of a "patch", i. e. a context diff against a certain (latest
4625official or latest in the git repository) version of U-Boot sources.
4626
4627But before you submit such a patch, please verify that your modifi-
4628cation did not break existing code. At least make sure that *ALL* of
4629the supported boards compile WITHOUT ANY compiler warnings. To do so,
4630just run the "MAKEALL" script, which will configure and build U-Boot
4631for ALL supported system. Be warned, this will take a while. You can
4632select which (cross) compiler to use by passing a `CROSS_COMPILE'
4633environment variable to the script, i. e. to use the ELDK cross tools
4634you can type
4635
4636	CROSS_COMPILE=ppc_8xx- MAKEALL
4637
4638or to build on a native PowerPC system you can type
4639
4640	CROSS_COMPILE=' ' MAKEALL
4641
4642When using the MAKEALL script, the default behaviour is to build
4643U-Boot in the source directory. This location can be changed by
4644setting the BUILD_DIR environment variable. Also, for each target
4645built, the MAKEALL script saves two log files (<target>.ERR and
4646<target>.MAKEALL) in the <source dir>/LOG directory. This default
4647location can be changed by setting the MAKEALL_LOGDIR environment
4648variable. For example:
4649
4650	export BUILD_DIR=/tmp/build
4651	export MAKEALL_LOGDIR=/tmp/log
4652	CROSS_COMPILE=ppc_8xx- MAKEALL
4653
4654With the above settings build objects are saved in the /tmp/build,
4655log files are saved in the /tmp/log and the source tree remains clean
4656during the whole build process.
4657
4658
4659See also "U-Boot Porting Guide" below.
4660
4661
4662Monitor Commands - Overview:
4663============================
4664
4665go	- start application at address 'addr'
4666run	- run commands in an environment variable
4667bootm	- boot application image from memory
4668bootp	- boot image via network using BootP/TFTP protocol
4669bootz   - boot zImage from memory
4670tftpboot- boot image via network using TFTP protocol
4671	       and env variables "ipaddr" and "serverip"
4672	       (and eventually "gatewayip")
4673tftpput - upload a file via network using TFTP protocol
4674rarpboot- boot image via network using RARP/TFTP protocol
4675diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4676loads	- load S-Record file over serial line
4677loadb	- load binary file over serial line (kermit mode)
4678md	- memory display
4679mm	- memory modify (auto-incrementing)
4680nm	- memory modify (constant address)
4681mw	- memory write (fill)
4682cp	- memory copy
4683cmp	- memory compare
4684crc32	- checksum calculation
4685i2c	- I2C sub-system
4686sspi	- SPI utility commands
4687base	- print or set address offset
4688printenv- print environment variables
4689setenv	- set environment variables
4690saveenv - save environment variables to persistent storage
4691protect - enable or disable FLASH write protection
4692erase	- erase FLASH memory
4693flinfo	- print FLASH memory information
4694nand	- NAND memory operations (see doc/README.nand)
4695bdinfo	- print Board Info structure
4696iminfo	- print header information for application image
4697coninfo - print console devices and informations
4698ide	- IDE sub-system
4699loop	- infinite loop on address range
4700loopw	- infinite write loop on address range
4701mtest	- simple RAM test
4702icache	- enable or disable instruction cache
4703dcache	- enable or disable data cache
4704reset	- Perform RESET of the CPU
4705echo	- echo args to console
4706version - print monitor version
4707help	- print online help
4708?	- alias for 'help'
4709
4710
4711Monitor Commands - Detailed Description:
4712========================================
4713
4714TODO.
4715
4716For now: just type "help <command>".
4717
4718
4719Environment Variables:
4720======================
4721
4722U-Boot supports user configuration using Environment Variables which
4723can be made persistent by saving to Flash memory.
4724
4725Environment Variables are set using "setenv", printed using
4726"printenv", and saved to Flash using "saveenv". Using "setenv"
4727without a value can be used to delete a variable from the
4728environment. As long as you don't save the environment you are
4729working with an in-memory copy. In case the Flash area containing the
4730environment is erased by accident, a default environment is provided.
4731
4732Some configuration options can be set using Environment Variables.
4733
4734List of environment variables (most likely not complete):
4735
4736  baudrate	- see CONFIG_BAUDRATE
4737
4738  bootdelay	- see CONFIG_BOOTDELAY
4739
4740  bootcmd	- see CONFIG_BOOTCOMMAND
4741
4742  bootargs	- Boot arguments when booting an RTOS image
4743
4744  bootfile	- Name of the image to load with TFTP
4745
4746  bootm_low	- Memory range available for image processing in the bootm
4747		  command can be restricted. This variable is given as
4748		  a hexadecimal number and defines lowest address allowed
4749		  for use by the bootm command. See also "bootm_size"
4750		  environment variable. Address defined by "bootm_low" is
4751		  also the base of the initial memory mapping for the Linux
4752		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
4753		  bootm_mapsize.
4754
4755  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
4756		  This variable is given as a hexadecimal number and it
4757		  defines the size of the memory region starting at base
4758		  address bootm_low that is accessible by the Linux kernel
4759		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
4760		  as the default value if it is defined, and bootm_size is
4761		  used otherwise.
4762
4763  bootm_size	- Memory range available for image processing in the bootm
4764		  command can be restricted. This variable is given as
4765		  a hexadecimal number and defines the size of the region
4766		  allowed for use by the bootm command. See also "bootm_low"
4767		  environment variable.
4768
4769  updatefile	- Location of the software update file on a TFTP server, used
4770		  by the automatic software update feature. Please refer to
4771		  documentation in doc/README.update for more details.
4772
4773  autoload	- if set to "no" (any string beginning with 'n'),
4774		  "bootp" will just load perform a lookup of the
4775		  configuration from the BOOTP server, but not try to
4776		  load any image using TFTP
4777
4778  autostart	- if set to "yes", an image loaded using the "bootp",
4779		  "rarpboot", "tftpboot" or "diskboot" commands will
4780		  be automatically started (by internally calling
4781		  "bootm")
4782
4783		  If set to "no", a standalone image passed to the
4784		  "bootm" command will be copied to the load address
4785		  (and eventually uncompressed), but NOT be started.
4786		  This can be used to load and uncompress arbitrary
4787		  data.
4788
4789  fdt_high	- if set this restricts the maximum address that the
4790		  flattened device tree will be copied into upon boot.
4791		  For example, if you have a system with 1 GB memory
4792		  at physical address 0x10000000, while Linux kernel
4793		  only recognizes the first 704 MB as low memory, you
4794		  may need to set fdt_high as 0x3C000000 to have the
4795		  device tree blob be copied to the maximum address
4796		  of the 704 MB low memory, so that Linux kernel can
4797		  access it during the boot procedure.
4798
4799		  If this is set to the special value 0xFFFFFFFF then
4800		  the fdt will not be copied at all on boot.  For this
4801		  to work it must reside in writable memory, have
4802		  sufficient padding on the end of it for u-boot to
4803		  add the information it needs into it, and the memory
4804		  must be accessible by the kernel.
4805
4806  fdtcontroladdr- if set this is the address of the control flattened
4807		  device tree used by U-Boot when CONFIG_OF_CONTROL is
4808		  defined.
4809
4810  i2cfast	- (PPC405GP|PPC405EP only)
4811		  if set to 'y' configures Linux I2C driver for fast
4812		  mode (400kHZ). This environment variable is used in
4813		  initialization code. So, for changes to be effective
4814		  it must be saved and board must be reset.
4815
4816  initrd_high	- restrict positioning of initrd images:
4817		  If this variable is not set, initrd images will be
4818		  copied to the highest possible address in RAM; this
4819		  is usually what you want since it allows for
4820		  maximum initrd size. If for some reason you want to
4821		  make sure that the initrd image is loaded below the
4822		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
4823		  variable to a value of "no" or "off" or "0".
4824		  Alternatively, you can set it to a maximum upper
4825		  address to use (U-Boot will still check that it
4826		  does not overwrite the U-Boot stack and data).
4827
4828		  For instance, when you have a system with 16 MB
4829		  RAM, and want to reserve 4 MB from use by Linux,
4830		  you can do this by adding "mem=12M" to the value of
4831		  the "bootargs" variable. However, now you must make
4832		  sure that the initrd image is placed in the first
4833		  12 MB as well - this can be done with
4834
4835		  setenv initrd_high 00c00000
4836
4837		  If you set initrd_high to 0xFFFFFFFF, this is an
4838		  indication to U-Boot that all addresses are legal
4839		  for the Linux kernel, including addresses in flash
4840		  memory. In this case U-Boot will NOT COPY the
4841		  ramdisk at all. This may be useful to reduce the
4842		  boot time on your system, but requires that this
4843		  feature is supported by your Linux kernel.
4844
4845  ipaddr	- IP address; needed for tftpboot command
4846
4847  loadaddr	- Default load address for commands like "bootp",
4848		  "rarpboot", "tftpboot", "loadb" or "diskboot"
4849
4850  loads_echo	- see CONFIG_LOADS_ECHO
4851
4852  serverip	- TFTP server IP address; needed for tftpboot command
4853
4854  bootretry	- see CONFIG_BOOT_RETRY_TIME
4855
4856  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
4857
4858  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
4859
4860  ethprime	- controls which interface is used first.
4861
4862  ethact	- controls which interface is currently active.
4863		  For example you can do the following
4864
4865		  => setenv ethact FEC
4866		  => ping 192.168.0.1 # traffic sent on FEC
4867		  => setenv ethact SCC
4868		  => ping 10.0.0.1 # traffic sent on SCC
4869
4870  ethrotate	- When set to "no" U-Boot does not go through all
4871		  available network interfaces.
4872		  It just stays at the currently selected interface.
4873
4874  netretry	- When set to "no" each network operation will
4875		  either succeed or fail without retrying.
4876		  When set to "once" the network operation will
4877		  fail when all the available network interfaces
4878		  are tried once without success.
4879		  Useful on scripts which control the retry operation
4880		  themselves.
4881
4882  npe_ucode	- set load address for the NPE microcode
4883
4884  silent_linux  - If set then linux will be told to boot silently, by
4885		  changing the console to be empty. If "yes" it will be
4886		  made silent. If "no" it will not be made silent. If
4887		  unset, then it will be made silent if the U-Boot console
4888		  is silent.
4889
4890  tftpsrcport	- If this is set, the value is used for TFTP's
4891		  UDP source port.
4892
4893  tftpdstport	- If this is set, the value is used for TFTP's UDP
4894		  destination port instead of the Well Know Port 69.
4895
4896  tftpblocksize - Block size to use for TFTP transfers; if not set,
4897		  we use the TFTP server's default block size
4898
4899  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
4900		  seconds, minimum value is 1000 = 1 second). Defines
4901		  when a packet is considered to be lost so it has to
4902		  be retransmitted. The default is 5000 = 5 seconds.
4903		  Lowering this value may make downloads succeed
4904		  faster in networks with high packet loss rates or
4905		  with unreliable TFTP servers.
4906
4907  vlan		- When set to a value < 4095 the traffic over
4908		  Ethernet is encapsulated/received over 802.1q
4909		  VLAN tagged frames.
4910
4911The following image location variables contain the location of images
4912used in booting. The "Image" column gives the role of the image and is
4913not an environment variable name. The other columns are environment
4914variable names. "File Name" gives the name of the file on a TFTP
4915server, "RAM Address" gives the location in RAM the image will be
4916loaded to, and "Flash Location" gives the image's address in NOR
4917flash or offset in NAND flash.
4918
4919*Note* - these variables don't have to be defined for all boards, some
4920boards currenlty use other variables for these purposes, and some
4921boards use these variables for other purposes.
4922
4923Image		    File Name	     RAM Address       Flash Location
4924-----		    ---------	     -----------       --------------
4925u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
4926Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
4927device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
4928ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
4929
4930The following environment variables may be used and automatically
4931updated by the network boot commands ("bootp" and "rarpboot"),
4932depending the information provided by your boot server:
4933
4934  bootfile	- see above
4935  dnsip		- IP address of your Domain Name Server
4936  dnsip2	- IP address of your secondary Domain Name Server
4937  gatewayip	- IP address of the Gateway (Router) to use
4938  hostname	- Target hostname
4939  ipaddr	- see above
4940  netmask	- Subnet Mask
4941  rootpath	- Pathname of the root filesystem on the NFS server
4942  serverip	- see above
4943
4944
4945There are two special Environment Variables:
4946
4947  serial#	- contains hardware identification information such
4948		  as type string and/or serial number
4949  ethaddr	- Ethernet address
4950
4951These variables can be set only once (usually during manufacturing of
4952the board). U-Boot refuses to delete or overwrite these variables
4953once they have been set once.
4954
4955
4956Further special Environment Variables:
4957
4958  ver		- Contains the U-Boot version string as printed
4959		  with the "version" command. This variable is
4960		  readonly (see CONFIG_VERSION_VARIABLE).
4961
4962
4963Please note that changes to some configuration parameters may take
4964only effect after the next boot (yes, that's just like Windoze :-).
4965
4966
4967Callback functions for environment variables:
4968---------------------------------------------
4969
4970For some environment variables, the behavior of u-boot needs to change
4971when their values are changed.  This functionailty allows functions to
4972be associated with arbitrary variables.  On creation, overwrite, or
4973deletion, the callback will provide the opportunity for some side
4974effect to happen or for the change to be rejected.
4975
4976The callbacks are named and associated with a function using the
4977U_BOOT_ENV_CALLBACK macro in your board or driver code.
4978
4979These callbacks are associated with variables in one of two ways.  The
4980static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
4981in the board configuration to a string that defines a list of
4982associations.  The list must be in the following format:
4983
4984	entry = variable_name[:callback_name]
4985	list = entry[,list]
4986
4987If the callback name is not specified, then the callback is deleted.
4988Spaces are also allowed anywhere in the list.
4989
4990Callbacks can also be associated by defining the ".callbacks" variable
4991with the same list format above.  Any association in ".callbacks" will
4992override any association in the static list. You can define
4993CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
4994".callbacks" envirnoment variable in the default or embedded environment.
4995
4996
4997Command Line Parsing:
4998=====================
4999
5000There are two different command line parsers available with U-Boot:
5001the old "simple" one, and the much more powerful "hush" shell:
5002
5003Old, simple command line parser:
5004--------------------------------
5005
5006- supports environment variables (through setenv / saveenv commands)
5007- several commands on one line, separated by ';'
5008- variable substitution using "... ${name} ..." syntax
5009- special characters ('$', ';') can be escaped by prefixing with '\',
5010  for example:
5011	setenv bootcmd bootm \${address}
5012- You can also escape text by enclosing in single apostrophes, for example:
5013	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
5014
5015Hush shell:
5016-----------
5017
5018- similar to Bourne shell, with control structures like
5019  if...then...else...fi, for...do...done; while...do...done,
5020  until...do...done, ...
5021- supports environment ("global") variables (through setenv / saveenv
5022  commands) and local shell variables (through standard shell syntax
5023  "name=value"); only environment variables can be used with "run"
5024  command
5025
5026General rules:
5027--------------
5028
5029(1) If a command line (or an environment variable executed by a "run"
5030    command) contains several commands separated by semicolon, and
5031    one of these commands fails, then the remaining commands will be
5032    executed anyway.
5033
5034(2) If you execute several variables with one call to run (i. e.
5035    calling run with a list of variables as arguments), any failing
5036    command will cause "run" to terminate, i. e. the remaining
5037    variables are not executed.
5038
5039Note for Redundant Ethernet Interfaces:
5040=======================================
5041
5042Some boards come with redundant Ethernet interfaces; U-Boot supports
5043such configurations and is capable of automatic selection of a
5044"working" interface when needed. MAC assignment works as follows:
5045
5046Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
5047MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
5048"eth1addr" (=>eth1), "eth2addr", ...
5049
5050If the network interface stores some valid MAC address (for instance
5051in SROM), this is used as default address if there is NO correspon-
5052ding setting in the environment; if the corresponding environment
5053variable is set, this overrides the settings in the card; that means:
5054
5055o If the SROM has a valid MAC address, and there is no address in the
5056  environment, the SROM's address is used.
5057
5058o If there is no valid address in the SROM, and a definition in the
5059  environment exists, then the value from the environment variable is
5060  used.
5061
5062o If both the SROM and the environment contain a MAC address, and
5063  both addresses are the same, this MAC address is used.
5064
5065o If both the SROM and the environment contain a MAC address, and the
5066  addresses differ, the value from the environment is used and a
5067  warning is printed.
5068
5069o If neither SROM nor the environment contain a MAC address, an error
5070  is raised.
5071
5072If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
5073will be programmed into hardware as part of the initialization process.	 This
5074may be skipped by setting the appropriate 'ethmacskip' environment variable.
5075The naming convention is as follows:
5076"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
5077
5078Image Formats:
5079==============
5080
5081U-Boot is capable of booting (and performing other auxiliary operations on)
5082images in two formats:
5083
5084New uImage format (FIT)
5085-----------------------
5086
5087Flexible and powerful format based on Flattened Image Tree -- FIT (similar
5088to Flattened Device Tree). It allows the use of images with multiple
5089components (several kernels, ramdisks, etc.), with contents protected by
5090SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
5091
5092
5093Old uImage format
5094-----------------
5095
5096Old image format is based on binary files which can be basically anything,
5097preceded by a special header; see the definitions in include/image.h for
5098details; basically, the header defines the following image properties:
5099
5100* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
5101  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
5102  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
5103  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
5104  INTEGRITY).
5105* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
5106  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
5107  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
5108* Compression Type (uncompressed, gzip, bzip2)
5109* Load Address
5110* Entry Point
5111* Image Name
5112* Image Timestamp
5113
5114The header is marked by a special Magic Number, and both the header
5115and the data portions of the image are secured against corruption by
5116CRC32 checksums.
5117
5118
5119Linux Support:
5120==============
5121
5122Although U-Boot should support any OS or standalone application
5123easily, the main focus has always been on Linux during the design of
5124U-Boot.
5125
5126U-Boot includes many features that so far have been part of some
5127special "boot loader" code within the Linux kernel. Also, any
5128"initrd" images to be used are no longer part of one big Linux image;
5129instead, kernel and "initrd" are separate images. This implementation
5130serves several purposes:
5131
5132- the same features can be used for other OS or standalone
5133  applications (for instance: using compressed images to reduce the
5134  Flash memory footprint)
5135
5136- it becomes much easier to port new Linux kernel versions because
5137  lots of low-level, hardware dependent stuff are done by U-Boot
5138
5139- the same Linux kernel image can now be used with different "initrd"
5140  images; of course this also means that different kernel images can
5141  be run with the same "initrd". This makes testing easier (you don't
5142  have to build a new "zImage.initrd" Linux image when you just
5143  change a file in your "initrd"). Also, a field-upgrade of the
5144  software is easier now.
5145
5146
5147Linux HOWTO:
5148============
5149
5150Porting Linux to U-Boot based systems:
5151---------------------------------------
5152
5153U-Boot cannot save you from doing all the necessary modifications to
5154configure the Linux device drivers for use with your target hardware
5155(no, we don't intend to provide a full virtual machine interface to
5156Linux :-).
5157
5158But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
5159
5160Just make sure your machine specific header file (for instance
5161include/asm-ppc/tqm8xx.h) includes the same definition of the Board
5162Information structure as we define in include/asm-<arch>/u-boot.h,
5163and make sure that your definition of IMAP_ADDR uses the same value
5164as your U-Boot configuration in CONFIG_SYS_IMMR.
5165
5166
5167Configuring the Linux kernel:
5168-----------------------------
5169
5170No specific requirements for U-Boot. Make sure you have some root
5171device (initial ramdisk, NFS) for your target system.
5172
5173
5174Building a Linux Image:
5175-----------------------
5176
5177With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5178not used. If you use recent kernel source, a new build target
5179"uImage" will exist which automatically builds an image usable by
5180U-Boot. Most older kernels also have support for a "pImage" target,
5181which was introduced for our predecessor project PPCBoot and uses a
5182100% compatible format.
5183
5184Example:
5185
5186	make TQM850L_config
5187	make oldconfig
5188	make dep
5189	make uImage
5190
5191The "uImage" build target uses a special tool (in 'tools/mkimage') to
5192encapsulate a compressed Linux kernel image with header	 information,
5193CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5194
5195* build a standard "vmlinux" kernel image (in ELF binary format):
5196
5197* convert the kernel into a raw binary image:
5198
5199	${CROSS_COMPILE}-objcopy -O binary \
5200				 -R .note -R .comment \
5201				 -S vmlinux linux.bin
5202
5203* compress the binary image:
5204
5205	gzip -9 linux.bin
5206
5207* package compressed binary image for U-Boot:
5208
5209	mkimage -A ppc -O linux -T kernel -C gzip \
5210		-a 0 -e 0 -n "Linux Kernel Image" \
5211		-d linux.bin.gz uImage
5212
5213
5214The "mkimage" tool can also be used to create ramdisk images for use
5215with U-Boot, either separated from the Linux kernel image, or
5216combined into one file. "mkimage" encapsulates the images with a 64
5217byte header containing information about target architecture,
5218operating system, image type, compression method, entry points, time
5219stamp, CRC32 checksums, etc.
5220
5221"mkimage" can be called in two ways: to verify existing images and
5222print the header information, or to build new images.
5223
5224In the first form (with "-l" option) mkimage lists the information
5225contained in the header of an existing U-Boot image; this includes
5226checksum verification:
5227
5228	tools/mkimage -l image
5229	  -l ==> list image header information
5230
5231The second form (with "-d" option) is used to build a U-Boot image
5232from a "data file" which is used as image payload:
5233
5234	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5235		      -n name -d data_file image
5236	  -A ==> set architecture to 'arch'
5237	  -O ==> set operating system to 'os'
5238	  -T ==> set image type to 'type'
5239	  -C ==> set compression type 'comp'
5240	  -a ==> set load address to 'addr' (hex)
5241	  -e ==> set entry point to 'ep' (hex)
5242	  -n ==> set image name to 'name'
5243	  -d ==> use image data from 'datafile'
5244
5245Right now, all Linux kernels for PowerPC systems use the same load
5246address (0x00000000), but the entry point address depends on the
5247kernel version:
5248
5249- 2.2.x kernels have the entry point at 0x0000000C,
5250- 2.3.x and later kernels have the entry point at 0x00000000.
5251
5252So a typical call to build a U-Boot image would read:
5253
5254	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5255	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5256	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5257	> examples/uImage.TQM850L
5258	Image Name:   2.4.4 kernel for TQM850L
5259	Created:      Wed Jul 19 02:34:59 2000
5260	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5261	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5262	Load Address: 0x00000000
5263	Entry Point:  0x00000000
5264
5265To verify the contents of the image (or check for corruption):
5266
5267	-> tools/mkimage -l examples/uImage.TQM850L
5268	Image Name:   2.4.4 kernel for TQM850L
5269	Created:      Wed Jul 19 02:34:59 2000
5270	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5271	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5272	Load Address: 0x00000000
5273	Entry Point:  0x00000000
5274
5275NOTE: for embedded systems where boot time is critical you can trade
5276speed for memory and install an UNCOMPRESSED image instead: this
5277needs more space in Flash, but boots much faster since it does not
5278need to be uncompressed:
5279
5280	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5281	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5282	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5283	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5284	> examples/uImage.TQM850L-uncompressed
5285	Image Name:   2.4.4 kernel for TQM850L
5286	Created:      Wed Jul 19 02:34:59 2000
5287	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5288	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5289	Load Address: 0x00000000
5290	Entry Point:  0x00000000
5291
5292
5293Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5294when your kernel is intended to use an initial ramdisk:
5295
5296	-> tools/mkimage -n 'Simple Ramdisk Image' \
5297	> -A ppc -O linux -T ramdisk -C gzip \
5298	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5299	Image Name:   Simple Ramdisk Image
5300	Created:      Wed Jan 12 14:01:50 2000
5301	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5302	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5303	Load Address: 0x00000000
5304	Entry Point:  0x00000000
5305
5306The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
5307option performs the converse operation of the mkimage's second form (the "-d"
5308option). Given an image built by mkimage, the dumpimage extracts a "data file"
5309from the image:
5310
5311	tools/dumpimage -i image -p position data_file
5312	  -i ==> extract from the 'image' a specific 'data_file', \
5313	   indexed by 'position'
5314
5315
5316Installing a Linux Image:
5317-------------------------
5318
5319To downloading a U-Boot image over the serial (console) interface,
5320you must convert the image to S-Record format:
5321
5322	objcopy -I binary -O srec examples/image examples/image.srec
5323
5324The 'objcopy' does not understand the information in the U-Boot
5325image header, so the resulting S-Record file will be relative to
5326address 0x00000000. To load it to a given address, you need to
5327specify the target address as 'offset' parameter with the 'loads'
5328command.
5329
5330Example: install the image to address 0x40100000 (which on the
5331TQM8xxL is in the first Flash bank):
5332
5333	=> erase 40100000 401FFFFF
5334
5335	.......... done
5336	Erased 8 sectors
5337
5338	=> loads 40100000
5339	## Ready for S-Record download ...
5340	~>examples/image.srec
5341	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5342	...
5343	15989 15990 15991 15992
5344	[file transfer complete]
5345	[connected]
5346	## Start Addr = 0x00000000
5347
5348
5349You can check the success of the download using the 'iminfo' command;
5350this includes a checksum verification so you can be sure no data
5351corruption happened:
5352
5353	=> imi 40100000
5354
5355	## Checking Image at 40100000 ...
5356	   Image Name:	 2.2.13 for initrd on TQM850L
5357	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5358	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5359	   Load Address: 00000000
5360	   Entry Point:	 0000000c
5361	   Verifying Checksum ... OK
5362
5363
5364Boot Linux:
5365-----------
5366
5367The "bootm" command is used to boot an application that is stored in
5368memory (RAM or Flash). In case of a Linux kernel image, the contents
5369of the "bootargs" environment variable is passed to the kernel as
5370parameters. You can check and modify this variable using the
5371"printenv" and "setenv" commands:
5372
5373
5374	=> printenv bootargs
5375	bootargs=root=/dev/ram
5376
5377	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5378
5379	=> printenv bootargs
5380	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5381
5382	=> bootm 40020000
5383	## Booting Linux kernel at 40020000 ...
5384	   Image Name:	 2.2.13 for NFS on TQM850L
5385	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5386	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5387	   Load Address: 00000000
5388	   Entry Point:	 0000000c
5389	   Verifying Checksum ... OK
5390	   Uncompressing Kernel Image ... OK
5391	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
5392	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5393	time_init: decrementer frequency = 187500000/60
5394	Calibrating delay loop... 49.77 BogoMIPS
5395	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5396	...
5397
5398If you want to boot a Linux kernel with initial RAM disk, you pass
5399the memory addresses of both the kernel and the initrd image (PPBCOOT
5400format!) to the "bootm" command:
5401
5402	=> imi 40100000 40200000
5403
5404	## Checking Image at 40100000 ...
5405	   Image Name:	 2.2.13 for initrd on TQM850L
5406	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5407	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5408	   Load Address: 00000000
5409	   Entry Point:	 0000000c
5410	   Verifying Checksum ... OK
5411
5412	## Checking Image at 40200000 ...
5413	   Image Name:	 Simple Ramdisk Image
5414	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5415	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5416	   Load Address: 00000000
5417	   Entry Point:	 00000000
5418	   Verifying Checksum ... OK
5419
5420	=> bootm 40100000 40200000
5421	## Booting Linux kernel at 40100000 ...
5422	   Image Name:	 2.2.13 for initrd on TQM850L
5423	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5424	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5425	   Load Address: 00000000
5426	   Entry Point:	 0000000c
5427	   Verifying Checksum ... OK
5428	   Uncompressing Kernel Image ... OK
5429	## Loading RAMDisk Image at 40200000 ...
5430	   Image Name:	 Simple Ramdisk Image
5431	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5432	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5433	   Load Address: 00000000
5434	   Entry Point:	 00000000
5435	   Verifying Checksum ... OK
5436	   Loading Ramdisk ... OK
5437	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
5438	Boot arguments: root=/dev/ram
5439	time_init: decrementer frequency = 187500000/60
5440	Calibrating delay loop... 49.77 BogoMIPS
5441	...
5442	RAMDISK: Compressed image found at block 0
5443	VFS: Mounted root (ext2 filesystem).
5444
5445	bash#
5446
5447Boot Linux and pass a flat device tree:
5448-----------
5449
5450First, U-Boot must be compiled with the appropriate defines. See the section
5451titled "Linux Kernel Interface" above for a more in depth explanation. The
5452following is an example of how to start a kernel and pass an updated
5453flat device tree:
5454
5455=> print oftaddr
5456oftaddr=0x300000
5457=> print oft
5458oft=oftrees/mpc8540ads.dtb
5459=> tftp $oftaddr $oft
5460Speed: 1000, full duplex
5461Using TSEC0 device
5462TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5463Filename 'oftrees/mpc8540ads.dtb'.
5464Load address: 0x300000
5465Loading: #
5466done
5467Bytes transferred = 4106 (100a hex)
5468=> tftp $loadaddr $bootfile
5469Speed: 1000, full duplex
5470Using TSEC0 device
5471TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5472Filename 'uImage'.
5473Load address: 0x200000
5474Loading:############
5475done
5476Bytes transferred = 1029407 (fb51f hex)
5477=> print loadaddr
5478loadaddr=200000
5479=> print oftaddr
5480oftaddr=0x300000
5481=> bootm $loadaddr - $oftaddr
5482## Booting image at 00200000 ...
5483   Image Name:	 Linux-2.6.17-dirty
5484   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5485   Data Size:	 1029343 Bytes = 1005.2 kB
5486   Load Address: 00000000
5487   Entry Point:	 00000000
5488   Verifying Checksum ... OK
5489   Uncompressing Kernel Image ... OK
5490Booting using flat device tree at 0x300000
5491Using MPC85xx ADS machine description
5492Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5493[snip]
5494
5495
5496More About U-Boot Image Types:
5497------------------------------
5498
5499U-Boot supports the following image types:
5500
5501   "Standalone Programs" are directly runnable in the environment
5502	provided by U-Boot; it is expected that (if they behave
5503	well) you can continue to work in U-Boot after return from
5504	the Standalone Program.
5505   "OS Kernel Images" are usually images of some Embedded OS which
5506	will take over control completely. Usually these programs
5507	will install their own set of exception handlers, device
5508	drivers, set up the MMU, etc. - this means, that you cannot
5509	expect to re-enter U-Boot except by resetting the CPU.
5510   "RAMDisk Images" are more or less just data blocks, and their
5511	parameters (address, size) are passed to an OS kernel that is
5512	being started.
5513   "Multi-File Images" contain several images, typically an OS
5514	(Linux) kernel image and one or more data images like
5515	RAMDisks. This construct is useful for instance when you want
5516	to boot over the network using BOOTP etc., where the boot
5517	server provides just a single image file, but you want to get
5518	for instance an OS kernel and a RAMDisk image.
5519
5520	"Multi-File Images" start with a list of image sizes, each
5521	image size (in bytes) specified by an "uint32_t" in network
5522	byte order. This list is terminated by an "(uint32_t)0".
5523	Immediately after the terminating 0 follow the images, one by
5524	one, all aligned on "uint32_t" boundaries (size rounded up to
5525	a multiple of 4 bytes).
5526
5527   "Firmware Images" are binary images containing firmware (like
5528	U-Boot or FPGA images) which usually will be programmed to
5529	flash memory.
5530
5531   "Script files" are command sequences that will be executed by
5532	U-Boot's command interpreter; this feature is especially
5533	useful when you configure U-Boot to use a real shell (hush)
5534	as command interpreter.
5535
5536Booting the Linux zImage:
5537-------------------------
5538
5539On some platforms, it's possible to boot Linux zImage. This is done
5540using the "bootz" command. The syntax of "bootz" command is the same
5541as the syntax of "bootm" command.
5542
5543Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5544kernel with raw initrd images. The syntax is slightly different, the
5545address of the initrd must be augmented by it's size, in the following
5546format: "<initrd addres>:<initrd size>".
5547
5548
5549Standalone HOWTO:
5550=================
5551
5552One of the features of U-Boot is that you can dynamically load and
5553run "standalone" applications, which can use some resources of
5554U-Boot like console I/O functions or interrupt services.
5555
5556Two simple examples are included with the sources:
5557
5558"Hello World" Demo:
5559-------------------
5560
5561'examples/hello_world.c' contains a small "Hello World" Demo
5562application; it is automatically compiled when you build U-Boot.
5563It's configured to run at address 0x00040004, so you can play with it
5564like that:
5565
5566	=> loads
5567	## Ready for S-Record download ...
5568	~>examples/hello_world.srec
5569	1 2 3 4 5 6 7 8 9 10 11 ...
5570	[file transfer complete]
5571	[connected]
5572	## Start Addr = 0x00040004
5573
5574	=> go 40004 Hello World! This is a test.
5575	## Starting application at 0x00040004 ...
5576	Hello World
5577	argc = 7
5578	argv[0] = "40004"
5579	argv[1] = "Hello"
5580	argv[2] = "World!"
5581	argv[3] = "This"
5582	argv[4] = "is"
5583	argv[5] = "a"
5584	argv[6] = "test."
5585	argv[7] = "<NULL>"
5586	Hit any key to exit ...
5587
5588	## Application terminated, rc = 0x0
5589
5590Another example, which demonstrates how to register a CPM interrupt
5591handler with the U-Boot code, can be found in 'examples/timer.c'.
5592Here, a CPM timer is set up to generate an interrupt every second.
5593The interrupt service routine is trivial, just printing a '.'
5594character, but this is just a demo program. The application can be
5595controlled by the following keys:
5596
5597	? - print current values og the CPM Timer registers
5598	b - enable interrupts and start timer
5599	e - stop timer and disable interrupts
5600	q - quit application
5601
5602	=> loads
5603	## Ready for S-Record download ...
5604	~>examples/timer.srec
5605	1 2 3 4 5 6 7 8 9 10 11 ...
5606	[file transfer complete]
5607	[connected]
5608	## Start Addr = 0x00040004
5609
5610	=> go 40004
5611	## Starting application at 0x00040004 ...
5612	TIMERS=0xfff00980
5613	Using timer 1
5614	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5615
5616Hit 'b':
5617	[q, b, e, ?] Set interval 1000000 us
5618	Enabling timer
5619Hit '?':
5620	[q, b, e, ?] ........
5621	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5622Hit '?':
5623	[q, b, e, ?] .
5624	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5625Hit '?':
5626	[q, b, e, ?] .
5627	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
5628Hit '?':
5629	[q, b, e, ?] .
5630	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
5631Hit 'e':
5632	[q, b, e, ?] ...Stopping timer
5633Hit 'q':
5634	[q, b, e, ?] ## Application terminated, rc = 0x0
5635
5636
5637Minicom warning:
5638================
5639
5640Over time, many people have reported problems when trying to use the
5641"minicom" terminal emulation program for serial download. I (wd)
5642consider minicom to be broken, and recommend not to use it. Under
5643Unix, I recommend to use C-Kermit for general purpose use (and
5644especially for kermit binary protocol download ("loadb" command), and
5645use "cu" for S-Record download ("loads" command).  See
5646http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
5647for help with kermit.
5648
5649
5650Nevertheless, if you absolutely want to use it try adding this
5651configuration to your "File transfer protocols" section:
5652
5653	   Name	   Program			Name U/D FullScr IO-Red. Multi
5654	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5655	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5656
5657
5658NetBSD Notes:
5659=============
5660
5661Starting at version 0.9.2, U-Boot supports NetBSD both as host
5662(build U-Boot) and target system (boots NetBSD/mpc8xx).
5663
5664Building requires a cross environment; it is known to work on
5665NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5666need gmake since the Makefiles are not compatible with BSD make).
5667Note that the cross-powerpc package does not install include files;
5668attempting to build U-Boot will fail because <machine/ansi.h> is
5669missing.  This file has to be installed and patched manually:
5670
5671	# cd /usr/pkg/cross/powerpc-netbsd/include
5672	# mkdir powerpc
5673	# ln -s powerpc machine
5674	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5675	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5676
5677Native builds *don't* work due to incompatibilities between native
5678and U-Boot include files.
5679
5680Booting assumes that (the first part of) the image booted is a
5681stage-2 loader which in turn loads and then invokes the kernel
5682proper. Loader sources will eventually appear in the NetBSD source
5683tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5684meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5685
5686
5687Implementation Internals:
5688=========================
5689
5690The following is not intended to be a complete description of every
5691implementation detail. However, it should help to understand the
5692inner workings of U-Boot and make it easier to port it to custom
5693hardware.
5694
5695
5696Initial Stack, Global Data:
5697---------------------------
5698
5699The implementation of U-Boot is complicated by the fact that U-Boot
5700starts running out of ROM (flash memory), usually without access to
5701system RAM (because the memory controller is not initialized yet).
5702This means that we don't have writable Data or BSS segments, and BSS
5703is not initialized as zero. To be able to get a C environment working
5704at all, we have to allocate at least a minimal stack. Implementation
5705options for this are defined and restricted by the CPU used: Some CPU
5706models provide on-chip memory (like the IMMR area on MPC8xx and
5707MPC826x processors), on others (parts of) the data cache can be
5708locked as (mis-) used as memory, etc.
5709
5710	Chris Hallinan posted a good summary of these issues to the
5711	U-Boot mailing list:
5712
5713	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
5714	From: "Chris Hallinan" <clh@net1plus.com>
5715	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
5716	...
5717
5718	Correct me if I'm wrong, folks, but the way I understand it
5719	is this: Using DCACHE as initial RAM for Stack, etc, does not
5720	require any physical RAM backing up the cache. The cleverness
5721	is that the cache is being used as a temporary supply of
5722	necessary storage before the SDRAM controller is setup. It's
5723	beyond the scope of this list to explain the details, but you
5724	can see how this works by studying the cache architecture and
5725	operation in the architecture and processor-specific manuals.
5726
5727	OCM is On Chip Memory, which I believe the 405GP has 4K. It
5728	is another option for the system designer to use as an
5729	initial stack/RAM area prior to SDRAM being available. Either
5730	option should work for you. Using CS 4 should be fine if your
5731	board designers haven't used it for something that would
5732	cause you grief during the initial boot! It is frequently not
5733	used.
5734
5735	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
5736	with your processor/board/system design. The default value
5737	you will find in any recent u-boot distribution in
5738	walnut.h should work for you. I'd set it to a value larger
5739	than your SDRAM module. If you have a 64MB SDRAM module, set
5740	it above 400_0000. Just make sure your board has no resources
5741	that are supposed to respond to that address! That code in
5742	start.S has been around a while and should work as is when
5743	you get the config right.
5744
5745	-Chris Hallinan
5746	DS4.COM, Inc.
5747
5748It is essential to remember this, since it has some impact on the C
5749code for the initialization procedures:
5750
5751* Initialized global data (data segment) is read-only. Do not attempt
5752  to write it.
5753
5754* Do not use any uninitialized global data (or implicitely initialized
5755  as zero data - BSS segment) at all - this is undefined, initiali-
5756  zation is performed later (when relocating to RAM).
5757
5758* Stack space is very limited. Avoid big data buffers or things like
5759  that.
5760
5761Having only the stack as writable memory limits means we cannot use
5762normal global data to share information beween the code. But it
5763turned out that the implementation of U-Boot can be greatly
5764simplified by making a global data structure (gd_t) available to all
5765functions. We could pass a pointer to this data as argument to _all_
5766functions, but this would bloat the code. Instead we use a feature of
5767the GCC compiler (Global Register Variables) to share the data: we
5768place a pointer (gd) to the global data into a register which we
5769reserve for this purpose.
5770
5771When choosing a register for such a purpose we are restricted by the
5772relevant  (E)ABI  specifications for the current architecture, and by
5773GCC's implementation.
5774
5775For PowerPC, the following registers have specific use:
5776	R1:	stack pointer
5777	R2:	reserved for system use
5778	R3-R4:	parameter passing and return values
5779	R5-R10: parameter passing
5780	R13:	small data area pointer
5781	R30:	GOT pointer
5782	R31:	frame pointer
5783
5784	(U-Boot also uses R12 as internal GOT pointer. r12
5785	is a volatile register so r12 needs to be reset when
5786	going back and forth between asm and C)
5787
5788    ==> U-Boot will use R2 to hold a pointer to the global data
5789
5790    Note: on PPC, we could use a static initializer (since the
5791    address of the global data structure is known at compile time),
5792    but it turned out that reserving a register results in somewhat
5793    smaller code - although the code savings are not that big (on
5794    average for all boards 752 bytes for the whole U-Boot image,
5795    624 text + 127 data).
5796
5797On Blackfin, the normal C ABI (except for P3) is followed as documented here:
5798	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
5799
5800    ==> U-Boot will use P3 to hold a pointer to the global data
5801
5802On ARM, the following registers are used:
5803
5804	R0:	function argument word/integer result
5805	R1-R3:	function argument word
5806	R9:	platform specific
5807	R10:	stack limit (used only if stack checking is enabled)
5808	R11:	argument (frame) pointer
5809	R12:	temporary workspace
5810	R13:	stack pointer
5811	R14:	link register
5812	R15:	program counter
5813
5814    ==> U-Boot will use R9 to hold a pointer to the global data
5815
5816    Note: on ARM, only R_ARM_RELATIVE relocations are supported.
5817
5818On Nios II, the ABI is documented here:
5819	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
5820
5821    ==> U-Boot will use gp to hold a pointer to the global data
5822
5823    Note: on Nios II, we give "-G0" option to gcc and don't use gp
5824    to access small data sections, so gp is free.
5825
5826On NDS32, the following registers are used:
5827
5828	R0-R1:	argument/return
5829	R2-R5:	argument
5830	R15:	temporary register for assembler
5831	R16:	trampoline register
5832	R28:	frame pointer (FP)
5833	R29:	global pointer (GP)
5834	R30:	link register (LP)
5835	R31:	stack pointer (SP)
5836	PC:	program counter (PC)
5837
5838    ==> U-Boot will use R10 to hold a pointer to the global data
5839
5840NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
5841or current versions of GCC may "optimize" the code too much.
5842
5843Memory Management:
5844------------------
5845
5846U-Boot runs in system state and uses physical addresses, i.e. the
5847MMU is not used either for address mapping nor for memory protection.
5848
5849The available memory is mapped to fixed addresses using the memory
5850controller. In this process, a contiguous block is formed for each
5851memory type (Flash, SDRAM, SRAM), even when it consists of several
5852physical memory banks.
5853
5854U-Boot is installed in the first 128 kB of the first Flash bank (on
5855TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
5856booting and sizing and initializing DRAM, the code relocates itself
5857to the upper end of DRAM. Immediately below the U-Boot code some
5858memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
5859configuration setting]. Below that, a structure with global Board
5860Info data is placed, followed by the stack (growing downward).
5861
5862Additionally, some exception handler code is copied to the low 8 kB
5863of DRAM (0x00000000 ... 0x00001FFF).
5864
5865So a typical memory configuration with 16 MB of DRAM could look like
5866this:
5867
5868	0x0000 0000	Exception Vector code
5869	      :
5870	0x0000 1FFF
5871	0x0000 2000	Free for Application Use
5872	      :
5873	      :
5874
5875	      :
5876	      :
5877	0x00FB FF20	Monitor Stack (Growing downward)
5878	0x00FB FFAC	Board Info Data and permanent copy of global data
5879	0x00FC 0000	Malloc Arena
5880	      :
5881	0x00FD FFFF
5882	0x00FE 0000	RAM Copy of Monitor Code
5883	...		eventually: LCD or video framebuffer
5884	...		eventually: pRAM (Protected RAM - unchanged by reset)
5885	0x00FF FFFF	[End of RAM]
5886
5887
5888System Initialization:
5889----------------------
5890
5891In the reset configuration, U-Boot starts at the reset entry point
5892(on most PowerPC systems at address 0x00000100). Because of the reset
5893configuration for CS0# this is a mirror of the onboard Flash memory.
5894To be able to re-map memory U-Boot then jumps to its link address.
5895To be able to implement the initialization code in C, a (small!)
5896initial stack is set up in the internal Dual Ported RAM (in case CPUs
5897which provide such a feature like MPC8xx or MPC8260), or in a locked
5898part of the data cache. After that, U-Boot initializes the CPU core,
5899the caches and the SIU.
5900
5901Next, all (potentially) available memory banks are mapped using a
5902preliminary mapping. For example, we put them on 512 MB boundaries
5903(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
5904on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
5905programmed for SDRAM access. Using the temporary configuration, a
5906simple memory test is run that determines the size of the SDRAM
5907banks.
5908
5909When there is more than one SDRAM bank, and the banks are of
5910different size, the largest is mapped first. For equal size, the first
5911bank (CS2#) is mapped first. The first mapping is always for address
59120x00000000, with any additional banks following immediately to create
5913contiguous memory starting from 0.
5914
5915Then, the monitor installs itself at the upper end of the SDRAM area
5916and allocates memory for use by malloc() and for the global Board
5917Info data; also, the exception vector code is copied to the low RAM
5918pages, and the final stack is set up.
5919
5920Only after this relocation will you have a "normal" C environment;
5921until that you are restricted in several ways, mostly because you are
5922running from ROM, and because the code will have to be relocated to a
5923new address in RAM.
5924
5925
5926U-Boot Porting Guide:
5927----------------------
5928
5929[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
5930list, October 2002]
5931
5932
5933int main(int argc, char *argv[])
5934{
5935	sighandler_t no_more_time;
5936
5937	signal(SIGALRM, no_more_time);
5938	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
5939
5940	if (available_money > available_manpower) {
5941		Pay consultant to port U-Boot;
5942		return 0;
5943	}
5944
5945	Download latest U-Boot source;
5946
5947	Subscribe to u-boot mailing list;
5948
5949	if (clueless)
5950		email("Hi, I am new to U-Boot, how do I get started?");
5951
5952	while (learning) {
5953		Read the README file in the top level directory;
5954		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
5955		Read applicable doc/*.README;
5956		Read the source, Luke;
5957		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
5958	}
5959
5960	if (available_money > toLocalCurrency ($2500))
5961		Buy a BDI3000;
5962	else
5963		Add a lot of aggravation and time;
5964
5965	if (a similar board exists) {	/* hopefully... */
5966		cp -a board/<similar> board/<myboard>
5967		cp include/configs/<similar>.h include/configs/<myboard>.h
5968	} else {
5969		Create your own board support subdirectory;
5970		Create your own board include/configs/<myboard>.h file;
5971	}
5972	Edit new board/<myboard> files
5973	Edit new include/configs/<myboard>.h
5974
5975	while (!accepted) {
5976		while (!running) {
5977			do {
5978				Add / modify source code;
5979			} until (compiles);
5980			Debug;
5981			if (clueless)
5982				email("Hi, I am having problems...");
5983		}
5984		Send patch file to the U-Boot email list;
5985		if (reasonable critiques)
5986			Incorporate improvements from email list code review;
5987		else
5988			Defend code as written;
5989	}
5990
5991	return 0;
5992}
5993
5994void no_more_time (int sig)
5995{
5996      hire_a_guru();
5997}
5998
5999
6000Coding Standards:
6001-----------------
6002
6003All contributions to U-Boot should conform to the Linux kernel
6004coding style; see the file "Documentation/CodingStyle" and the script
6005"scripts/Lindent" in your Linux kernel source directory.
6006
6007Source files originating from a different project (for example the
6008MTD subsystem) are generally exempt from these guidelines and are not
6009reformated to ease subsequent migration to newer versions of those
6010sources.
6011
6012Please note that U-Boot is implemented in C (and to some small parts in
6013Assembler); no C++ is used, so please do not use C++ style comments (//)
6014in your code.
6015
6016Please also stick to the following formatting rules:
6017- remove any trailing white space
6018- use TAB characters for indentation and vertical alignment, not spaces
6019- make sure NOT to use DOS '\r\n' line feeds
6020- do not add more than 2 consecutive empty lines to source files
6021- do not add trailing empty lines to source files
6022
6023Submissions which do not conform to the standards may be returned
6024with a request to reformat the changes.
6025
6026
6027Submitting Patches:
6028-------------------
6029
6030Since the number of patches for U-Boot is growing, we need to
6031establish some rules. Submissions which do not conform to these rules
6032may be rejected, even when they contain important and valuable stuff.
6033
6034Please see http://www.denx.de/wiki/U-Boot/Patches for details.
6035
6036Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
6037see http://lists.denx.de/mailman/listinfo/u-boot
6038
6039When you send a patch, please include the following information with
6040it:
6041
6042* For bug fixes: a description of the bug and how your patch fixes
6043  this bug. Please try to include a way of demonstrating that the
6044  patch actually fixes something.
6045
6046* For new features: a description of the feature and your
6047  implementation.
6048
6049* A CHANGELOG entry as plaintext (separate from the patch)
6050
6051* For major contributions, your entry to the CREDITS file
6052
6053* When you add support for a new board, don't forget to add a
6054  maintainer e-mail address to the boards.cfg file, too.
6055
6056* If your patch adds new configuration options, don't forget to
6057  document these in the README file.
6058
6059* The patch itself. If you are using git (which is *strongly*
6060  recommended) you can easily generate the patch using the
6061  "git format-patch". If you then use "git send-email" to send it to
6062  the U-Boot mailing list, you will avoid most of the common problems
6063  with some other mail clients.
6064
6065  If you cannot use git, use "diff -purN OLD NEW". If your version of
6066  diff does not support these options, then get the latest version of
6067  GNU diff.
6068
6069  The current directory when running this command shall be the parent
6070  directory of the U-Boot source tree (i. e. please make sure that
6071  your patch includes sufficient directory information for the
6072  affected files).
6073
6074  We prefer patches as plain text. MIME attachments are discouraged,
6075  and compressed attachments must not be used.
6076
6077* If one logical set of modifications affects or creates several
6078  files, all these changes shall be submitted in a SINGLE patch file.
6079
6080* Changesets that contain different, unrelated modifications shall be
6081  submitted as SEPARATE patches, one patch per changeset.
6082
6083
6084Notes:
6085
6086* Before sending the patch, run the MAKEALL script on your patched
6087  source tree and make sure that no errors or warnings are reported
6088  for any of the boards.
6089
6090* Keep your modifications to the necessary minimum: A patch
6091  containing several unrelated changes or arbitrary reformats will be
6092  returned with a request to re-formatting / split it.
6093
6094* If you modify existing code, make sure that your new code does not
6095  add to the memory footprint of the code ;-) Small is beautiful!
6096  When adding new features, these should compile conditionally only
6097  (using #ifdef), and the resulting code with the new feature
6098  disabled must not need more memory than the old code without your
6099  modification.
6100
6101* Remember that there is a size limit of 100 kB per message on the
6102  u-boot mailing list. Bigger patches will be moderated. If they are
6103  reasonable and not too big, they will be acknowledged. But patches
6104  bigger than the size limit should be avoided.
6105