xref: /rk3399_rockchip-uboot/README (revision 6b9e309a8a7f0f33252288f0ed8794a83a488301)
1#
2# (C) Copyright 2000 - 2013
3# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
4#
5# SPDX-License-Identifier:	GPL-2.0+
6#
7
8Summary:
9========
10
11This directory contains the source code for U-Boot, a boot loader for
12Embedded boards based on PowerPC, ARM, MIPS and several other
13processors, which can be installed in a boot ROM and used to
14initialize and test the hardware or to download and run application
15code.
16
17The development of U-Boot is closely related to Linux: some parts of
18the source code originate in the Linux source tree, we have some
19header files in common, and special provision has been made to
20support booting of Linux images.
21
22Some attention has been paid to make this software easily
23configurable and extendable. For instance, all monitor commands are
24implemented with the same call interface, so that it's very easy to
25add new commands. Also, instead of permanently adding rarely used
26code (for instance hardware test utilities) to the monitor, you can
27load and run it dynamically.
28
29
30Status:
31=======
32
33In general, all boards for which a configuration option exists in the
34Makefile have been tested to some extent and can be considered
35"working". In fact, many of them are used in production systems.
36
37In case of problems see the CHANGELOG and CREDITS files to find out
38who contributed the specific port. The boards.cfg file lists board
39maintainers.
40
41Note: There is no CHANGELOG file in the actual U-Boot source tree;
42it can be created dynamically from the Git log using:
43
44	make CHANGELOG
45
46
47Where to get help:
48==================
49
50In case you have questions about, problems with or contributions for
51U-Boot you should send a message to the U-Boot mailing list at
52<u-boot@lists.denx.de>. There is also an archive of previous traffic
53on the mailing list - please search the archive before asking FAQ's.
54Please see http://lists.denx.de/pipermail/u-boot and
55http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
56
57
58Where to get source code:
59=========================
60
61The U-Boot source code is maintained in the git repository at
62git://www.denx.de/git/u-boot.git ; you can browse it online at
63http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
64
65The "snapshot" links on this page allow you to download tarballs of
66any version you might be interested in. Official releases are also
67available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
68directory.
69
70Pre-built (and tested) images are available from
71ftp://ftp.denx.de/pub/u-boot/images/
72
73
74Where we come from:
75===================
76
77- start from 8xxrom sources
78- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
79- clean up code
80- make it easier to add custom boards
81- make it possible to add other [PowerPC] CPUs
82- extend functions, especially:
83  * Provide extended interface to Linux boot loader
84  * S-Record download
85  * network boot
86  * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
87- create ARMBoot project (http://sourceforge.net/projects/armboot)
88- add other CPU families (starting with ARM)
89- create U-Boot project (http://sourceforge.net/projects/u-boot)
90- current project page: see http://www.denx.de/wiki/U-Boot
91
92
93Names and Spelling:
94===================
95
96The "official" name of this project is "Das U-Boot". The spelling
97"U-Boot" shall be used in all written text (documentation, comments
98in source files etc.). Example:
99
100	This is the README file for the U-Boot project.
101
102File names etc. shall be based on the string "u-boot". Examples:
103
104	include/asm-ppc/u-boot.h
105
106	#include <asm/u-boot.h>
107
108Variable names, preprocessor constants etc. shall be either based on
109the string "u_boot" or on "U_BOOT". Example:
110
111	U_BOOT_VERSION		u_boot_logo
112	IH_OS_U_BOOT		u_boot_hush_start
113
114
115Versioning:
116===========
117
118Starting with the release in October 2008, the names of the releases
119were changed from numerical release numbers without deeper meaning
120into a time stamp based numbering. Regular releases are identified by
121names consisting of the calendar year and month of the release date.
122Additional fields (if present) indicate release candidates or bug fix
123releases in "stable" maintenance trees.
124
125Examples:
126	U-Boot v2009.11	    - Release November 2009
127	U-Boot v2009.11.1   - Release 1 in version November 2009 stable tree
128	U-Boot v2010.09-rc1 - Release candiate 1 for September 2010 release
129
130
131Directory Hierarchy:
132====================
133
134/arch			Architecture specific files
135  /arm			Files generic to ARM architecture
136    /cpu		CPU specific files
137      /arm720t		Files specific to ARM 720 CPUs
138      /arm920t		Files specific to ARM 920 CPUs
139	/at91		Files specific to Atmel AT91RM9200 CPU
140	/imx		Files specific to Freescale MC9328 i.MX CPUs
141	/s3c24x0	Files specific to Samsung S3C24X0 CPUs
142      /arm926ejs	Files specific to ARM 926 CPUs
143      /arm1136		Files specific to ARM 1136 CPUs
144      /pxa		Files specific to Intel XScale PXA CPUs
145      /sa1100		Files specific to Intel StrongARM SA1100 CPUs
146    /lib		Architecture specific library files
147  /avr32		Files generic to AVR32 architecture
148    /cpu		CPU specific files
149    /lib		Architecture specific library files
150  /blackfin		Files generic to Analog Devices Blackfin architecture
151    /cpu		CPU specific files
152    /lib		Architecture specific library files
153  /m68k			Files generic to m68k architecture
154    /cpu		CPU specific files
155      /mcf52x2		Files specific to Freescale ColdFire MCF52x2 CPUs
156      /mcf5227x		Files specific to Freescale ColdFire MCF5227x CPUs
157      /mcf532x		Files specific to Freescale ColdFire MCF5329 CPUs
158      /mcf5445x		Files specific to Freescale ColdFire MCF5445x CPUs
159      /mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
160    /lib		Architecture specific library files
161  /microblaze		Files generic to microblaze architecture
162    /cpu		CPU specific files
163    /lib		Architecture specific library files
164  /mips			Files generic to MIPS architecture
165    /cpu		CPU specific files
166      /mips32		Files specific to MIPS32 CPUs
167      /xburst		Files specific to Ingenic XBurst CPUs
168    /lib		Architecture specific library files
169  /nds32		Files generic to NDS32 architecture
170    /cpu		CPU specific files
171      /n1213		Files specific to Andes Technology N1213 CPUs
172    /lib		Architecture specific library files
173  /nios2		Files generic to Altera NIOS2 architecture
174    /cpu		CPU specific files
175    /lib		Architecture specific library files
176  /openrisc		Files generic to OpenRISC architecture
177    /cpu		CPU specific files
178    /lib		Architecture specific library files
179  /powerpc		Files generic to PowerPC architecture
180    /cpu		CPU specific files
181      /74xx_7xx		Files specific to Freescale MPC74xx and 7xx CPUs
182      /mpc5xx		Files specific to Freescale MPC5xx CPUs
183      /mpc5xxx		Files specific to Freescale MPC5xxx CPUs
184      /mpc8xx		Files specific to Freescale MPC8xx CPUs
185      /mpc824x		Files specific to Freescale MPC824x CPUs
186      /mpc8260		Files specific to Freescale MPC8260 CPUs
187      /mpc85xx		Files specific to Freescale MPC85xx CPUs
188      /ppc4xx		Files specific to AMCC PowerPC 4xx CPUs
189    /lib		Architecture specific library files
190  /sh			Files generic to SH architecture
191    /cpu		CPU specific files
192      /sh2		Files specific to sh2 CPUs
193      /sh3		Files specific to sh3 CPUs
194      /sh4		Files specific to sh4 CPUs
195    /lib		Architecture specific library files
196  /sparc		Files generic to SPARC architecture
197    /cpu		CPU specific files
198      /leon2		Files specific to Gaisler LEON2 SPARC CPU
199      /leon3		Files specific to Gaisler LEON3 SPARC CPU
200    /lib		Architecture specific library files
201  /x86			Files generic to x86 architecture
202    /cpu		CPU specific files
203    /lib		Architecture specific library files
204/api			Machine/arch independent API for external apps
205/board			Board dependent files
206/common			Misc architecture independent functions
207/disk			Code for disk drive partition handling
208/doc			Documentation (don't expect too much)
209/drivers		Commonly used device drivers
210/dts			Contains Makefile for building internal U-Boot fdt.
211/examples		Example code for standalone applications, etc.
212/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
213/include		Header Files
214/lib			Files generic to all architectures
215  /libfdt		Library files to support flattened device trees
216  /lzma			Library files to support LZMA decompression
217  /lzo			Library files to support LZO decompression
218/net			Networking code
219/post			Power On Self Test
220/spl			Secondary Program Loader framework
221/tools			Tools to build S-Record or U-Boot images, etc.
222
223Software Configuration:
224=======================
225
226Configuration is usually done using C preprocessor defines; the
227rationale behind that is to avoid dead code whenever possible.
228
229There are two classes of configuration variables:
230
231* Configuration _OPTIONS_:
232  These are selectable by the user and have names beginning with
233  "CONFIG_".
234
235* Configuration _SETTINGS_:
236  These depend on the hardware etc. and should not be meddled with if
237  you don't know what you're doing; they have names beginning with
238  "CONFIG_SYS_".
239
240Later we will add a configuration tool - probably similar to or even
241identical to what's used for the Linux kernel. Right now, we have to
242do the configuration by hand, which means creating some symbolic
243links and editing some configuration files. We use the TQM8xxL boards
244as an example here.
245
246
247Selection of Processor Architecture and Board Type:
248---------------------------------------------------
249
250For all supported boards there are ready-to-use default
251configurations available; just type "make <board_name>_config".
252
253Example: For a TQM823L module type:
254
255	cd u-boot
256	make TQM823L_config
257
258For the Cogent platform, you need to specify the CPU type as well;
259e.g. "make cogent_mpc8xx_config". And also configure the cogent
260directory according to the instructions in cogent/README.
261
262
263Configuration Options:
264----------------------
265
266Configuration depends on the combination of board and CPU type; all
267such information is kept in a configuration file
268"include/configs/<board_name>.h".
269
270Example: For a TQM823L module, all configuration settings are in
271"include/configs/TQM823L.h".
272
273
274Many of the options are named exactly as the corresponding Linux
275kernel configuration options. The intention is to make it easier to
276build a config tool - later.
277
278
279The following options need to be configured:
280
281- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
282
283- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
284
285- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
286		Define exactly one, e.g. CONFIG_ATSTK1002
287
288- CPU Module Type: (if CONFIG_COGENT is defined)
289		Define exactly one of
290		CONFIG_CMA286_60_OLD
291--- FIXME --- not tested yet:
292		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
293		CONFIG_CMA287_23, CONFIG_CMA287_50
294
295- Motherboard Type: (if CONFIG_COGENT is defined)
296		Define exactly one of
297		CONFIG_CMA101, CONFIG_CMA102
298
299- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
300		Define one or more of
301		CONFIG_CMA302
302
303- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
304		Define one or more of
305		CONFIG_LCD_HEARTBEAT	- update a character position on
306					  the LCD display every second with
307					  a "rotator" |\-/|\-/
308
309- Board flavour: (if CONFIG_MPC8260ADS is defined)
310		CONFIG_ADSTYPE
311		Possible values are:
312			CONFIG_SYS_8260ADS	- original MPC8260ADS
313			CONFIG_SYS_8266ADS	- MPC8266ADS
314			CONFIG_SYS_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
315			CONFIG_SYS_8272ADS	- MPC8272ADS
316
317- Marvell Family Member
318		CONFIG_SYS_MVFS		- define it if you want to enable
319					  multiple fs option at one time
320					  for marvell soc family
321
322- MPC824X Family Member (if CONFIG_MPC824X is defined)
323		Define exactly one of
324		CONFIG_MPC8240, CONFIG_MPC8245
325
326- 8xx CPU Options: (if using an MPC8xx CPU)
327		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
328					  get_gclk_freq() cannot work
329					  e.g. if there is no 32KHz
330					  reference PIT/RTC clock
331		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
332					  or XTAL/EXTAL)
333
334- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
335		CONFIG_SYS_8xx_CPUCLK_MIN
336		CONFIG_SYS_8xx_CPUCLK_MAX
337		CONFIG_8xx_CPUCLK_DEFAULT
338			See doc/README.MPC866
339
340		CONFIG_SYS_MEASURE_CPUCLK
341
342		Define this to measure the actual CPU clock instead
343		of relying on the correctness of the configured
344		values. Mostly useful for board bringup to make sure
345		the PLL is locked at the intended frequency. Note
346		that this requires a (stable) reference clock (32 kHz
347		RTC clock or CONFIG_SYS_8XX_XIN)
348
349		CONFIG_SYS_DELAYED_ICACHE
350
351		Define this option if you want to enable the
352		ICache only when Code runs from RAM.
353
354- 85xx CPU Options:
355		CONFIG_SYS_PPC64
356
357		Specifies that the core is a 64-bit PowerPC implementation (implements
358		the "64" category of the Power ISA). This is necessary for ePAPR
359		compliance, among other possible reasons.
360
361		CONFIG_SYS_FSL_TBCLK_DIV
362
363		Defines the core time base clock divider ratio compared to the
364		system clock.  On most PQ3 devices this is 8, on newer QorIQ
365		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
366
367		CONFIG_SYS_FSL_PCIE_COMPAT
368
369		Defines the string to utilize when trying to match PCIe device
370		tree nodes for the given platform.
371
372		CONFIG_SYS_PPC_E500_DEBUG_TLB
373
374		Enables a temporary TLB entry to be used during boot to work
375		around limitations in e500v1 and e500v2 external debugger
376		support. This reduces the portions of the boot code where
377		breakpoints and single stepping do not work.  The value of this
378		symbol should be set to the TLB1 entry to be used for this
379		purpose.
380
381		CONFIG_SYS_FSL_ERRATUM_A004510
382
383		Enables a workaround for erratum A004510.  If set,
384		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
385		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
386
387		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
388		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
389
390		Defines one or two SoC revisions (low 8 bits of SVR)
391		for which the A004510 workaround should be applied.
392
393		The rest of SVR is either not relevant to the decision
394		of whether the erratum is present (e.g. p2040 versus
395		p2041) or is implied by the build target, which controls
396		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
397
398		See Freescale App Note 4493 for more information about
399		this erratum.
400
401		CONFIG_A003399_NOR_WORKAROUND
402		Enables a workaround for IFC erratum A003399. It is only
403		requred during NOR boot.
404
405		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
406
407		This is the value to write into CCSR offset 0x18600
408		according to the A004510 workaround.
409
410		CONFIG_SYS_FSL_DSP_DDR_ADDR
411		This value denotes start offset of DDR memory which is
412		connected exclusively to the DSP cores.
413
414		CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
415		This value denotes start offset of M2 memory
416		which is directly connected to the DSP core.
417
418		CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
419		This value denotes start offset of M3 memory which is directly
420		connected to the DSP core.
421
422		CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
423		This value denotes start offset of DSP CCSR space.
424
425		CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
426		Single Source Clock is clocking mode present in some of FSL SoC's.
427		In this mode, a single differential clock is used to supply
428		clocks to the sysclock, ddrclock and usbclock.
429
430- Generic CPU options:
431		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
432
433		Defines the endianess of the CPU. Implementation of those
434		values is arch specific.
435
436		CONFIG_SYS_FSL_DDR
437		Freescale DDR driver in use. This type of DDR controller is
438		found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
439		SoCs.
440
441		CONFIG_SYS_FSL_DDR_ADDR
442		Freescale DDR memory-mapped register base.
443
444		CONFIG_SYS_FSL_DDR_EMU
445		Specify emulator support for DDR. Some DDR features such as
446		deskew training are not available.
447
448		CONFIG_SYS_FSL_DDRC_GEN1
449		Freescale DDR1 controller.
450
451		CONFIG_SYS_FSL_DDRC_GEN2
452		Freescale DDR2 controller.
453
454		CONFIG_SYS_FSL_DDRC_GEN3
455		Freescale DDR3 controller.
456
457		CONFIG_SYS_FSL_DDRC_ARM_GEN3
458		Freescale DDR3 controller for ARM-based SoCs.
459
460		CONFIG_SYS_FSL_DDR1
461		Board config to use DDR1. It can be enabled for SoCs with
462		Freescale DDR1 or DDR2 controllers, depending on the board
463		implemetation.
464
465		CONFIG_SYS_FSL_DDR2
466		Board config to use DDR2. It can be eanbeld for SoCs with
467		Freescale DDR2 or DDR3 controllers, depending on the board
468		implementation.
469
470		CONFIG_SYS_FSL_DDR3
471		Board config to use DDR3. It can be enabled for SoCs with
472		Freescale DDR3 controllers.
473
474		CONFIG_SYS_FSL_IFC_BE
475		Defines the IFC controller register space as Big Endian
476
477		CONFIG_SYS_FSL_IFC_LE
478		Defines the IFC controller register space as Little Endian
479
480		CONFIG_SYS_FSL_PBL_PBI
481		It enables addition of RCW (Power on reset configuration) in built image.
482		Please refer doc/README.pblimage for more details
483
484		CONFIG_SYS_FSL_PBL_RCW
485		It adds PBI(pre-boot instructions) commands in u-boot build image.
486		PBI commands can be used to configure SoC before it starts the execution.
487		Please refer doc/README.pblimage for more details
488
489		CONFIG_SYS_FSL_DDR_BE
490		Defines the DDR controller register space as Big Endian
491
492		CONFIG_SYS_FSL_DDR_LE
493		Defines the DDR controller register space as Little Endian
494
495		CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
496		Physical address from the view of DDR controllers. It is the
497		same as CONFIG_SYS_DDR_SDRAM_BASE for  all Power SoCs. But
498		it could be different for ARM SoCs.
499
500- Intel Monahans options:
501		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
502
503		Defines the Monahans run mode to oscillator
504		ratio. Valid values are 8, 16, 24, 31. The core
505		frequency is this value multiplied by 13 MHz.
506
507		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
508
509		Defines the Monahans turbo mode to oscillator
510		ratio. Valid values are 1 (default if undefined) and
511		2. The core frequency as calculated above is multiplied
512		by this value.
513
514- MIPS CPU options:
515		CONFIG_SYS_INIT_SP_OFFSET
516
517		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
518		pointer. This is needed for the temporary stack before
519		relocation.
520
521		CONFIG_SYS_MIPS_CACHE_MODE
522
523		Cache operation mode for the MIPS CPU.
524		See also arch/mips/include/asm/mipsregs.h.
525		Possible values are:
526			CONF_CM_CACHABLE_NO_WA
527			CONF_CM_CACHABLE_WA
528			CONF_CM_UNCACHED
529			CONF_CM_CACHABLE_NONCOHERENT
530			CONF_CM_CACHABLE_CE
531			CONF_CM_CACHABLE_COW
532			CONF_CM_CACHABLE_CUW
533			CONF_CM_CACHABLE_ACCELERATED
534
535		CONFIG_SYS_XWAY_EBU_BOOTCFG
536
537		Special option for Lantiq XWAY SoCs for booting from NOR flash.
538		See also arch/mips/cpu/mips32/start.S.
539
540		CONFIG_XWAY_SWAP_BYTES
541
542		Enable compilation of tools/xway-swap-bytes needed for Lantiq
543		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
544		be swapped if a flash programmer is used.
545
546- ARM options:
547		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
548
549		Select high exception vectors of the ARM core, e.g., do not
550		clear the V bit of the c1 register of CP15.
551
552		CONFIG_SYS_THUMB_BUILD
553
554		Use this flag to build U-Boot using the Thumb instruction
555		set for ARM architectures. Thumb instruction set provides
556		better code density. For ARM architectures that support
557		Thumb2 this flag will result in Thumb2 code generated by
558		GCC.
559
560		CONFIG_ARM_ERRATA_716044
561		CONFIG_ARM_ERRATA_742230
562		CONFIG_ARM_ERRATA_743622
563		CONFIG_ARM_ERRATA_751472
564
565		If set, the workarounds for these ARM errata are applied early
566		during U-Boot startup. Note that these options force the
567		workarounds to be applied; no CPU-type/version detection
568		exists, unlike the similar options in the Linux kernel. Do not
569		set these options unless they apply!
570
571- CPU timer options:
572		CONFIG_SYS_HZ
573
574		The frequency of the timer returned by get_timer().
575		get_timer() must operate in milliseconds and this CONFIG
576		option must be set to 1000.
577
578- Linux Kernel Interface:
579		CONFIG_CLOCKS_IN_MHZ
580
581		U-Boot stores all clock information in Hz
582		internally. For binary compatibility with older Linux
583		kernels (which expect the clocks passed in the
584		bd_info data to be in MHz) the environment variable
585		"clocks_in_mhz" can be defined so that U-Boot
586		converts clock data to MHZ before passing it to the
587		Linux kernel.
588		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
589		"clocks_in_mhz=1" is automatically included in the
590		default environment.
591
592		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
593
594		When transferring memsize parameter to linux, some versions
595		expect it to be in bytes, others in MB.
596		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
597
598		CONFIG_OF_LIBFDT
599
600		New kernel versions are expecting firmware settings to be
601		passed using flattened device trees (based on open firmware
602		concepts).
603
604		CONFIG_OF_LIBFDT
605		 * New libfdt-based support
606		 * Adds the "fdt" command
607		 * The bootm command automatically updates the fdt
608
609		OF_CPU - The proper name of the cpus node (only required for
610			MPC512X and MPC5xxx based boards).
611		OF_SOC - The proper name of the soc node (only required for
612			MPC512X and MPC5xxx based boards).
613		OF_TBCLK - The timebase frequency.
614		OF_STDOUT_PATH - The path to the console device
615
616		boards with QUICC Engines require OF_QE to set UCC MAC
617		addresses
618
619		CONFIG_OF_BOARD_SETUP
620
621		Board code has addition modification that it wants to make
622		to the flat device tree before handing it off to the kernel
623
624		CONFIG_OF_BOOT_CPU
625
626		This define fills in the correct boot CPU in the boot
627		param header, the default value is zero if undefined.
628
629		CONFIG_OF_IDE_FIXUP
630
631		U-Boot can detect if an IDE device is present or not.
632		If not, and this new config option is activated, U-Boot
633		removes the ATA node from the DTS before booting Linux,
634		so the Linux IDE driver does not probe the device and
635		crash. This is needed for buggy hardware (uc101) where
636		no pull down resistor is connected to the signal IDE5V_DD7.
637
638		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
639
640		This setting is mandatory for all boards that have only one
641		machine type and must be used to specify the machine type
642		number as it appears in the ARM machine registry
643		(see http://www.arm.linux.org.uk/developer/machines/).
644		Only boards that have multiple machine types supported
645		in a single configuration file and the machine type is
646		runtime discoverable, do not have to use this setting.
647
648- vxWorks boot parameters:
649
650		bootvx constructs a valid bootline using the following
651		environments variables: bootfile, ipaddr, serverip, hostname.
652		It loads the vxWorks image pointed bootfile.
653
654		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
655		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
656		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
657		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
658
659		CONFIG_SYS_VXWORKS_ADD_PARAMS
660
661		Add it at the end of the bootline. E.g "u=username pw=secret"
662
663		Note: If a "bootargs" environment is defined, it will overwride
664		the defaults discussed just above.
665
666- Cache Configuration:
667		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
668		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
669		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
670
671- Cache Configuration for ARM:
672		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
673				      controller
674		CONFIG_SYS_PL310_BASE - Physical base address of PL310
675					controller register space
676
677- Serial Ports:
678		CONFIG_PL010_SERIAL
679
680		Define this if you want support for Amba PrimeCell PL010 UARTs.
681
682		CONFIG_PL011_SERIAL
683
684		Define this if you want support for Amba PrimeCell PL011 UARTs.
685
686		CONFIG_PL011_CLOCK
687
688		If you have Amba PrimeCell PL011 UARTs, set this variable to
689		the clock speed of the UARTs.
690
691		CONFIG_PL01x_PORTS
692
693		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
694		define this to a list of base addresses for each (supported)
695		port. See e.g. include/configs/versatile.h
696
697		CONFIG_PL011_SERIAL_RLCR
698
699		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
700		have separate receive and transmit line control registers.  Set
701		this variable to initialize the extra register.
702
703		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
704
705		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
706		boot loader that has already initialized the UART.  Define this
707		variable to flush the UART at init time.
708
709
710- Console Interface:
711		Depending on board, define exactly one serial port
712		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
713		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
714		console by defining CONFIG_8xx_CONS_NONE
715
716		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
717		port routines must be defined elsewhere
718		(i.e. serial_init(), serial_getc(), ...)
719
720		CONFIG_CFB_CONSOLE
721		Enables console device for a color framebuffer. Needs following
722		defines (cf. smiLynxEM, i8042)
723			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
724						(default big endian)
725			VIDEO_HW_RECTFILL	graphic chip supports
726						rectangle fill
727						(cf. smiLynxEM)
728			VIDEO_HW_BITBLT		graphic chip supports
729						bit-blit (cf. smiLynxEM)
730			VIDEO_VISIBLE_COLS	visible pixel columns
731						(cols=pitch)
732			VIDEO_VISIBLE_ROWS	visible pixel rows
733			VIDEO_PIXEL_SIZE	bytes per pixel
734			VIDEO_DATA_FORMAT	graphic data format
735						(0-5, cf. cfb_console.c)
736			VIDEO_FB_ADRS		framebuffer address
737			VIDEO_KBD_INIT_FCT	keyboard int fct
738						(i.e. i8042_kbd_init())
739			VIDEO_TSTC_FCT		test char fct
740						(i.e. i8042_tstc)
741			VIDEO_GETC_FCT		get char fct
742						(i.e. i8042_getc)
743			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
744						(requires blink timer
745						cf. i8042.c)
746			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
747			CONFIG_CONSOLE_TIME	display time/date info in
748						upper right corner
749						(requires CONFIG_CMD_DATE)
750			CONFIG_VIDEO_LOGO	display Linux logo in
751						upper left corner
752			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
753						linux_logo.h for logo.
754						Requires CONFIG_VIDEO_LOGO
755			CONFIG_CONSOLE_EXTRA_INFO
756						additional board info beside
757						the logo
758
759		When CONFIG_CFB_CONSOLE_ANSI is defined, console will support
760		a limited number of ANSI escape sequences (cursor control,
761		erase functions and limited graphics rendition control).
762
763		When CONFIG_CFB_CONSOLE is defined, video console is
764		default i/o. Serial console can be forced with
765		environment 'console=serial'.
766
767		When CONFIG_SILENT_CONSOLE is defined, all console
768		messages (by U-Boot and Linux!) can be silenced with
769		the "silent" environment variable. See
770		doc/README.silent for more information.
771
772		CONFIG_SYS_CONSOLE_BG_COL: define the backgroundcolor, default
773			is 0x00.
774		CONFIG_SYS_CONSOLE_FG_COL: define the foregroundcolor, default
775			is 0xa0.
776
777- Console Baudrate:
778		CONFIG_BAUDRATE - in bps
779		Select one of the baudrates listed in
780		CONFIG_SYS_BAUDRATE_TABLE, see below.
781		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
782
783- Console Rx buffer length
784		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
785		the maximum receive buffer length for the SMC.
786		This option is actual only for 82xx and 8xx possible.
787		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
788		must be defined, to setup the maximum idle timeout for
789		the SMC.
790
791- Pre-Console Buffer:
792		Prior to the console being initialised (i.e. serial UART
793		initialised etc) all console output is silently discarded.
794		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
795		buffer any console messages prior to the console being
796		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
797		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
798		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
799		bytes are output before the console is initialised, the
800		earlier bytes are discarded.
801
802		'Sane' compilers will generate smaller code if
803		CONFIG_PRE_CON_BUF_SZ is a power of 2
804
805- Safe printf() functions
806		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
807		the printf() functions. These are defined in
808		include/vsprintf.h and include snprintf(), vsnprintf() and
809		so on. Code size increase is approximately 300-500 bytes.
810		If this option is not given then these functions will
811		silently discard their buffer size argument - this means
812		you are not getting any overflow checking in this case.
813
814- Boot Delay:	CONFIG_BOOTDELAY - in seconds
815		Delay before automatically booting the default image;
816		set to -1 to disable autoboot.
817		set to -2 to autoboot with no delay and not check for abort
818		(even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).
819
820		See doc/README.autoboot for these options that
821		work with CONFIG_BOOTDELAY. None are required.
822		CONFIG_BOOT_RETRY_TIME
823		CONFIG_BOOT_RETRY_MIN
824		CONFIG_AUTOBOOT_KEYED
825		CONFIG_AUTOBOOT_PROMPT
826		CONFIG_AUTOBOOT_DELAY_STR
827		CONFIG_AUTOBOOT_STOP_STR
828		CONFIG_AUTOBOOT_DELAY_STR2
829		CONFIG_AUTOBOOT_STOP_STR2
830		CONFIG_ZERO_BOOTDELAY_CHECK
831		CONFIG_RESET_TO_RETRY
832
833- Autoboot Command:
834		CONFIG_BOOTCOMMAND
835		Only needed when CONFIG_BOOTDELAY is enabled;
836		define a command string that is automatically executed
837		when no character is read on the console interface
838		within "Boot Delay" after reset.
839
840		CONFIG_BOOTARGS
841		This can be used to pass arguments to the bootm
842		command. The value of CONFIG_BOOTARGS goes into the
843		environment value "bootargs".
844
845		CONFIG_RAMBOOT and CONFIG_NFSBOOT
846		The value of these goes into the environment as
847		"ramboot" and "nfsboot" respectively, and can be used
848		as a convenience, when switching between booting from
849		RAM and NFS.
850
851- Bootcount:
852		CONFIG_BOOTCOUNT_LIMIT
853		Implements a mechanism for detecting a repeating reboot
854		cycle, see:
855		http://www.denx.de/wiki/view/DULG/UBootBootCountLimit
856
857		CONFIG_BOOTCOUNT_ENV
858		If no softreset save registers are found on the hardware
859		"bootcount" is stored in the environment. To prevent a
860		saveenv on all reboots, the environment variable
861		"upgrade_available" is used. If "upgrade_available" is
862		0, "bootcount" is always 0, if "upgrade_available" is
863		1 "bootcount" is incremented in the environment.
864		So the Userspace Applikation must set the "upgrade_available"
865		and "bootcount" variable to 0, if a boot was successfully.
866
867- Pre-Boot Commands:
868		CONFIG_PREBOOT
869
870		When this option is #defined, the existence of the
871		environment variable "preboot" will be checked
872		immediately before starting the CONFIG_BOOTDELAY
873		countdown and/or running the auto-boot command resp.
874		entering interactive mode.
875
876		This feature is especially useful when "preboot" is
877		automatically generated or modified. For an example
878		see the LWMON board specific code: here "preboot" is
879		modified when the user holds down a certain
880		combination of keys on the (special) keyboard when
881		booting the systems
882
883- Serial Download Echo Mode:
884		CONFIG_LOADS_ECHO
885		If defined to 1, all characters received during a
886		serial download (using the "loads" command) are
887		echoed back. This might be needed by some terminal
888		emulations (like "cu"), but may as well just take
889		time on others. This setting #define's the initial
890		value of the "loads_echo" environment variable.
891
892- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
893		CONFIG_KGDB_BAUDRATE
894		Select one of the baudrates listed in
895		CONFIG_SYS_BAUDRATE_TABLE, see below.
896
897- Monitor Functions:
898		Monitor commands can be included or excluded
899		from the build by using the #include files
900		<config_cmd_all.h> and #undef'ing unwanted
901		commands, or using <config_cmd_default.h>
902		and augmenting with additional #define's
903		for wanted commands.
904
905		The default command configuration includes all commands
906		except those marked below with a "*".
907
908		CONFIG_CMD_ASKENV	* ask for env variable
909		CONFIG_CMD_BDI		  bdinfo
910		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
911		CONFIG_CMD_BMP		* BMP support
912		CONFIG_CMD_BSP		* Board specific commands
913		CONFIG_CMD_BOOTD	  bootd
914		CONFIG_CMD_CACHE	* icache, dcache
915		CONFIG_CMD_CLK   	* clock command support
916		CONFIG_CMD_CONSOLE	  coninfo
917		CONFIG_CMD_CRC32	* crc32
918		CONFIG_CMD_DATE		* support for RTC, date/time...
919		CONFIG_CMD_DHCP		* DHCP support
920		CONFIG_CMD_DIAG		* Diagnostics
921		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
922		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
923		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
924		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
925		CONFIG_CMD_DTT		* Digital Therm and Thermostat
926		CONFIG_CMD_ECHO		  echo arguments
927		CONFIG_CMD_EDITENV	  edit env variable
928		CONFIG_CMD_EEPROM	* EEPROM read/write support
929		CONFIG_CMD_ELF		* bootelf, bootvx
930		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
931		CONFIG_CMD_ENV_FLAGS	* display details about env flags
932		CONFIG_CMD_ENV_EXISTS	* check existence of env variable
933		CONFIG_CMD_EXPORTENV	* export the environment
934		CONFIG_CMD_EXT2		* ext2 command support
935		CONFIG_CMD_EXT4		* ext4 command support
936		CONFIG_CMD_FS_GENERIC	* filesystem commands (e.g. load, ls)
937					  that work for multiple fs types
938		CONFIG_CMD_SAVEENV	  saveenv
939		CONFIG_CMD_FDC		* Floppy Disk Support
940		CONFIG_CMD_FAT		* FAT command support
941		CONFIG_CMD_FLASH	  flinfo, erase, protect
942		CONFIG_CMD_FPGA		  FPGA device initialization support
943		CONFIG_CMD_FUSE		* Device fuse support
944		CONFIG_CMD_GETTIME	* Get time since boot
945		CONFIG_CMD_GO		* the 'go' command (exec code)
946		CONFIG_CMD_GREPENV	* search environment
947		CONFIG_CMD_HASH		* calculate hash / digest
948		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
949		CONFIG_CMD_I2C		* I2C serial bus support
950		CONFIG_CMD_IDE		* IDE harddisk support
951		CONFIG_CMD_IMI		  iminfo
952		CONFIG_CMD_IMLS		  List all images found in NOR flash
953		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash
954		CONFIG_CMD_IMMAP	* IMMR dump support
955		CONFIG_CMD_IMPORTENV	* import an environment
956		CONFIG_CMD_INI		* import data from an ini file into the env
957		CONFIG_CMD_IRQ		* irqinfo
958		CONFIG_CMD_ITEST	  Integer/string test of 2 values
959		CONFIG_CMD_JFFS2	* JFFS2 Support
960		CONFIG_CMD_KGDB		* kgdb
961		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)
962		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
963					  (169.254.*.*)
964		CONFIG_CMD_LOADB	  loadb
965		CONFIG_CMD_LOADS	  loads
966		CONFIG_CMD_MD5SUM	* print md5 message digest
967					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
968		CONFIG_CMD_MEMINFO	* Display detailed memory information
969		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
970					  loop, loopw
971		CONFIG_CMD_MEMTEST	* mtest
972		CONFIG_CMD_MISC		  Misc functions like sleep etc
973		CONFIG_CMD_MMC		* MMC memory mapped support
974		CONFIG_CMD_MII		* MII utility commands
975		CONFIG_CMD_MTDPARTS	* MTD partition support
976		CONFIG_CMD_NAND		* NAND support
977		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
978		CONFIG_CMD_NFS		  NFS support
979		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
980		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
981		CONFIG_CMD_PCI		* pciinfo
982		CONFIG_CMD_PCMCIA		* PCMCIA support
983		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
984					  host
985		CONFIG_CMD_PORTIO	* Port I/O
986		CONFIG_CMD_READ		* Read raw data from partition
987		CONFIG_CMD_REGINFO	* Register dump
988		CONFIG_CMD_RUN		  run command in env variable
989		CONFIG_CMD_SANDBOX	* sb command to access sandbox features
990		CONFIG_CMD_SAVES	* save S record dump
991		CONFIG_CMD_SCSI		* SCSI Support
992		CONFIG_CMD_SDRAM	* print SDRAM configuration information
993					  (requires CONFIG_CMD_I2C)
994		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
995					  (4xx only)
996		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
997		CONFIG_CMD_SHA1SUM	* print sha1 memory digest
998					  (requires CONFIG_CMD_MEMORY)
999		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x
1000		CONFIG_CMD_SOURCE	  "source" command Support
1001		CONFIG_CMD_SPI		* SPI serial bus support
1002		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
1003		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
1004		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
1005		CONFIG_CMD_TIMER	* access to the system tick timer
1006		CONFIG_CMD_USB		* USB support
1007		CONFIG_CMD_CDP		* Cisco Discover Protocol support
1008		CONFIG_CMD_MFSL		* Microblaze FSL support
1009		CONFIG_CMD_XIMG		  Load part of Multi Image
1010
1011
1012		EXAMPLE: If you want all functions except of network
1013		support you can write:
1014
1015		#include "config_cmd_all.h"
1016		#undef CONFIG_CMD_NET
1017
1018	Other Commands:
1019		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
1020
1021	Note:	Don't enable the "icache" and "dcache" commands
1022		(configuration option CONFIG_CMD_CACHE) unless you know
1023		what you (and your U-Boot users) are doing. Data
1024		cache cannot be enabled on systems like the 8xx or
1025		8260 (where accesses to the IMMR region must be
1026		uncached), and it cannot be disabled on all other
1027		systems where we (mis-) use the data cache to hold an
1028		initial stack and some data.
1029
1030
1031		XXX - this list needs to get updated!
1032
1033- Regular expression support:
1034		CONFIG_REGEX
1035		If this variable is defined, U-Boot is linked against
1036		the SLRE (Super Light Regular Expression) library,
1037		which adds regex support to some commands, as for
1038		example "env grep" and "setexpr".
1039
1040- Device tree:
1041		CONFIG_OF_CONTROL
1042		If this variable is defined, U-Boot will use a device tree
1043		to configure its devices, instead of relying on statically
1044		compiled #defines in the board file. This option is
1045		experimental and only available on a few boards. The device
1046		tree is available in the global data as gd->fdt_blob.
1047
1048		U-Boot needs to get its device tree from somewhere. This can
1049		be done using one of the two options below:
1050
1051		CONFIG_OF_EMBED
1052		If this variable is defined, U-Boot will embed a device tree
1053		binary in its image. This device tree file should be in the
1054		board directory and called <soc>-<board>.dts. The binary file
1055		is then picked up in board_init_f() and made available through
1056		the global data structure as gd->blob.
1057
1058		CONFIG_OF_SEPARATE
1059		If this variable is defined, U-Boot will build a device tree
1060		binary. It will be called u-boot.dtb. Architecture-specific
1061		code will locate it at run-time. Generally this works by:
1062
1063			cat u-boot.bin u-boot.dtb >image.bin
1064
1065		and in fact, U-Boot does this for you, creating a file called
1066		u-boot-dtb.bin which is useful in the common case. You can
1067		still use the individual files if you need something more
1068		exotic.
1069
1070- Watchdog:
1071		CONFIG_WATCHDOG
1072		If this variable is defined, it enables watchdog
1073		support for the SoC. There must be support in the SoC
1074		specific code for a watchdog. For the 8xx and 8260
1075		CPUs, the SIU Watchdog feature is enabled in the SYPCR
1076		register.  When supported for a specific SoC is
1077		available, then no further board specific code should
1078		be needed to use it.
1079
1080		CONFIG_HW_WATCHDOG
1081		When using a watchdog circuitry external to the used
1082		SoC, then define this variable and provide board
1083		specific code for the "hw_watchdog_reset" function.
1084
1085- U-Boot Version:
1086		CONFIG_VERSION_VARIABLE
1087		If this variable is defined, an environment variable
1088		named "ver" is created by U-Boot showing the U-Boot
1089		version as printed by the "version" command.
1090		Any change to this variable will be reverted at the
1091		next reset.
1092
1093- Real-Time Clock:
1094
1095		When CONFIG_CMD_DATE is selected, the type of the RTC
1096		has to be selected, too. Define exactly one of the
1097		following options:
1098
1099		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
1100		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
1101		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
1102		CONFIG_RTC_MC146818	- use MC146818 RTC
1103		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
1104		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
1105		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
1106		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
1107		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
1108		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
1109		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
1110		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
1111					  RV3029 RTC.
1112
1113		Note that if the RTC uses I2C, then the I2C interface
1114		must also be configured. See I2C Support, below.
1115
1116- GPIO Support:
1117		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
1118
1119		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1120		chip-ngpio pairs that tell the PCA953X driver the number of
1121		pins supported by a particular chip.
1122
1123		Note that if the GPIO device uses I2C, then the I2C interface
1124		must also be configured. See I2C Support, below.
1125
1126- Timestamp Support:
1127
1128		When CONFIG_TIMESTAMP is selected, the timestamp
1129		(date and time) of an image is printed by image
1130		commands like bootm or iminfo. This option is
1131		automatically enabled when you select CONFIG_CMD_DATE .
1132
1133- Partition Labels (disklabels) Supported:
1134		Zero or more of the following:
1135		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1136		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1137				       Intel architecture, USB sticks, etc.
1138		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1139		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1140				       bootloader.  Note 2TB partition limit; see
1141				       disk/part_efi.c
1142		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1143
1144		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1145		CONFIG_CMD_SCSI) you must configure support for at
1146		least one non-MTD partition type as well.
1147
1148- IDE Reset method:
1149		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1150		board configurations files but used nowhere!
1151
1152		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1153		be performed by calling the function
1154			ide_set_reset(int reset)
1155		which has to be defined in a board specific file
1156
1157- ATAPI Support:
1158		CONFIG_ATAPI
1159
1160		Set this to enable ATAPI support.
1161
1162- LBA48 Support
1163		CONFIG_LBA48
1164
1165		Set this to enable support for disks larger than 137GB
1166		Also look at CONFIG_SYS_64BIT_LBA.
1167		Whithout these , LBA48 support uses 32bit variables and will 'only'
1168		support disks up to 2.1TB.
1169
1170		CONFIG_SYS_64BIT_LBA:
1171			When enabled, makes the IDE subsystem use 64bit sector addresses.
1172			Default is 32bit.
1173
1174- SCSI Support:
1175		At the moment only there is only support for the
1176		SYM53C8XX SCSI controller; define
1177		CONFIG_SCSI_SYM53C8XX to enable it.
1178
1179		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1180		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1181		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1182		maximum numbers of LUNs, SCSI ID's and target
1183		devices.
1184		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1185
1186		The environment variable 'scsidevs' is set to the number of
1187		SCSI devices found during the last scan.
1188
1189- NETWORK Support (PCI):
1190		CONFIG_E1000
1191		Support for Intel 8254x/8257x gigabit chips.
1192
1193		CONFIG_E1000_SPI
1194		Utility code for direct access to the SPI bus on Intel 8257x.
1195		This does not do anything useful unless you set at least one
1196		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1197
1198		CONFIG_E1000_SPI_GENERIC
1199		Allow generic access to the SPI bus on the Intel 8257x, for
1200		example with the "sspi" command.
1201
1202		CONFIG_CMD_E1000
1203		Management command for E1000 devices.  When used on devices
1204		with SPI support you can reprogram the EEPROM from U-Boot.
1205
1206		CONFIG_E1000_FALLBACK_MAC
1207		default MAC for empty EEPROM after production.
1208
1209		CONFIG_EEPRO100
1210		Support for Intel 82557/82559/82559ER chips.
1211		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1212		write routine for first time initialisation.
1213
1214		CONFIG_TULIP
1215		Support for Digital 2114x chips.
1216		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1217		modem chip initialisation (KS8761/QS6611).
1218
1219		CONFIG_NATSEMI
1220		Support for National dp83815 chips.
1221
1222		CONFIG_NS8382X
1223		Support for National dp8382[01] gigabit chips.
1224
1225- NETWORK Support (other):
1226
1227		CONFIG_DRIVER_AT91EMAC
1228		Support for AT91RM9200 EMAC.
1229
1230			CONFIG_RMII
1231			Define this to use reduced MII inteface
1232
1233			CONFIG_DRIVER_AT91EMAC_QUIET
1234			If this defined, the driver is quiet.
1235			The driver doen't show link status messages.
1236
1237		CONFIG_CALXEDA_XGMAC
1238		Support for the Calxeda XGMAC device
1239
1240		CONFIG_LAN91C96
1241		Support for SMSC's LAN91C96 chips.
1242
1243			CONFIG_LAN91C96_BASE
1244			Define this to hold the physical address
1245			of the LAN91C96's I/O space
1246
1247			CONFIG_LAN91C96_USE_32_BIT
1248			Define this to enable 32 bit addressing
1249
1250		CONFIG_SMC91111
1251		Support for SMSC's LAN91C111 chip
1252
1253			CONFIG_SMC91111_BASE
1254			Define this to hold the physical address
1255			of the device (I/O space)
1256
1257			CONFIG_SMC_USE_32_BIT
1258			Define this if data bus is 32 bits
1259
1260			CONFIG_SMC_USE_IOFUNCS
1261			Define this to use i/o functions instead of macros
1262			(some hardware wont work with macros)
1263
1264		CONFIG_DRIVER_TI_EMAC
1265		Support for davinci emac
1266
1267			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1268			Define this if you have more then 3 PHYs.
1269
1270		CONFIG_FTGMAC100
1271		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1272
1273			CONFIG_FTGMAC100_EGIGA
1274			Define this to use GE link update with gigabit PHY.
1275			Define this if FTGMAC100 is connected to gigabit PHY.
1276			If your system has 10/100 PHY only, it might not occur
1277			wrong behavior. Because PHY usually return timeout or
1278			useless data when polling gigabit status and gigabit
1279			control registers. This behavior won't affect the
1280			correctnessof 10/100 link speed update.
1281
1282		CONFIG_SMC911X
1283		Support for SMSC's LAN911x and LAN921x chips
1284
1285			CONFIG_SMC911X_BASE
1286			Define this to hold the physical address
1287			of the device (I/O space)
1288
1289			CONFIG_SMC911X_32_BIT
1290			Define this if data bus is 32 bits
1291
1292			CONFIG_SMC911X_16_BIT
1293			Define this if data bus is 16 bits. If your processor
1294			automatically converts one 32 bit word to two 16 bit
1295			words you may also try CONFIG_SMC911X_32_BIT.
1296
1297		CONFIG_SH_ETHER
1298		Support for Renesas on-chip Ethernet controller
1299
1300			CONFIG_SH_ETHER_USE_PORT
1301			Define the number of ports to be used
1302
1303			CONFIG_SH_ETHER_PHY_ADDR
1304			Define the ETH PHY's address
1305
1306			CONFIG_SH_ETHER_CACHE_WRITEBACK
1307			If this option is set, the driver enables cache flush.
1308
1309- TPM Support:
1310		CONFIG_TPM
1311		Support TPM devices.
1312
1313		CONFIG_TPM_TIS_I2C
1314		Support for i2c bus TPM devices. Only one device
1315		per system is supported at this time.
1316
1317			CONFIG_TPM_TIS_I2C_BUS_NUMBER
1318			Define the the i2c bus number for the TPM device
1319
1320			CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS
1321			Define the TPM's address on the i2c bus
1322
1323			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1324			Define the burst count bytes upper limit
1325
1326		CONFIG_TPM_ATMEL_TWI
1327		Support for Atmel TWI TPM device. Requires I2C support.
1328
1329		CONFIG_TPM_TIS_LPC
1330		Support for generic parallel port TPM devices. Only one device
1331		per system is supported at this time.
1332
1333			CONFIG_TPM_TIS_BASE_ADDRESS
1334			Base address where the generic TPM device is mapped
1335			to. Contemporary x86 systems usually map it at
1336			0xfed40000.
1337
1338		CONFIG_CMD_TPM
1339		Add tpm monitor functions.
1340		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1341		provides monitor access to authorized functions.
1342
1343		CONFIG_TPM
1344		Define this to enable the TPM support library which provides
1345		functional interfaces to some TPM commands.
1346		Requires support for a TPM device.
1347
1348		CONFIG_TPM_AUTH_SESSIONS
1349		Define this to enable authorized functions in the TPM library.
1350		Requires CONFIG_TPM and CONFIG_SHA1.
1351
1352- USB Support:
1353		At the moment only the UHCI host controller is
1354		supported (PIP405, MIP405, MPC5200); define
1355		CONFIG_USB_UHCI to enable it.
1356		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1357		and define CONFIG_USB_STORAGE to enable the USB
1358		storage devices.
1359		Note:
1360		Supported are USB Keyboards and USB Floppy drives
1361		(TEAC FD-05PUB).
1362		MPC5200 USB requires additional defines:
1363			CONFIG_USB_CLOCK
1364				for 528 MHz Clock: 0x0001bbbb
1365			CONFIG_PSC3_USB
1366				for USB on PSC3
1367			CONFIG_USB_CONFIG
1368				for differential drivers: 0x00001000
1369				for single ended drivers: 0x00005000
1370				for differential drivers on PSC3: 0x00000100
1371				for single ended drivers on PSC3: 0x00004100
1372			CONFIG_SYS_USB_EVENT_POLL
1373				May be defined to allow interrupt polling
1374				instead of using asynchronous interrupts
1375
1376		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1377		txfilltuning field in the EHCI controller on reset.
1378
1379		CONFIG_USB_HUB_MIN_POWER_ON_DELAY defines the minimum
1380		interval for usb hub power-on delay.(minimum 100msec)
1381
1382- USB Device:
1383		Define the below if you wish to use the USB console.
1384		Once firmware is rebuilt from a serial console issue the
1385		command "setenv stdin usbtty; setenv stdout usbtty" and
1386		attach your USB cable. The Unix command "dmesg" should print
1387		it has found a new device. The environment variable usbtty
1388		can be set to gserial or cdc_acm to enable your device to
1389		appear to a USB host as a Linux gserial device or a
1390		Common Device Class Abstract Control Model serial device.
1391		If you select usbtty = gserial you should be able to enumerate
1392		a Linux host by
1393		# modprobe usbserial vendor=0xVendorID product=0xProductID
1394		else if using cdc_acm, simply setting the environment
1395		variable usbtty to be cdc_acm should suffice. The following
1396		might be defined in YourBoardName.h
1397
1398			CONFIG_USB_DEVICE
1399			Define this to build a UDC device
1400
1401			CONFIG_USB_TTY
1402			Define this to have a tty type of device available to
1403			talk to the UDC device
1404
1405			CONFIG_USBD_HS
1406			Define this to enable the high speed support for usb
1407			device and usbtty. If this feature is enabled, a routine
1408			int is_usbd_high_speed(void)
1409			also needs to be defined by the driver to dynamically poll
1410			whether the enumeration has succeded at high speed or full
1411			speed.
1412
1413			CONFIG_SYS_CONSOLE_IS_IN_ENV
1414			Define this if you want stdin, stdout &/or stderr to
1415			be set to usbtty.
1416
1417			mpc8xx:
1418				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1419				Derive USB clock from external clock "blah"
1420				- CONFIG_SYS_USB_EXTC_CLK 0x02
1421
1422				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1423				Derive USB clock from brgclk
1424				- CONFIG_SYS_USB_BRG_CLK 0x04
1425
1426		If you have a USB-IF assigned VendorID then you may wish to
1427		define your own vendor specific values either in BoardName.h
1428		or directly in usbd_vendor_info.h. If you don't define
1429		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1430		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1431		should pretend to be a Linux device to it's target host.
1432
1433			CONFIG_USBD_MANUFACTURER
1434			Define this string as the name of your company for
1435			- CONFIG_USBD_MANUFACTURER "my company"
1436
1437			CONFIG_USBD_PRODUCT_NAME
1438			Define this string as the name of your product
1439			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1440
1441			CONFIG_USBD_VENDORID
1442			Define this as your assigned Vendor ID from the USB
1443			Implementors Forum. This *must* be a genuine Vendor ID
1444			to avoid polluting the USB namespace.
1445			- CONFIG_USBD_VENDORID 0xFFFF
1446
1447			CONFIG_USBD_PRODUCTID
1448			Define this as the unique Product ID
1449			for your device
1450			- CONFIG_USBD_PRODUCTID 0xFFFF
1451
1452		Some USB device drivers may need to check USB cable attachment.
1453		In this case you can enable following config in BoardName.h:
1454			CONFIG_USB_CABLE_CHECK
1455			This enables function definition:
1456			- usb_cable_connected() in include/usb.h
1457			Implementation of this function is board-specific.
1458
1459- ULPI Layer Support:
1460		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1461		the generic ULPI layer. The generic layer accesses the ULPI PHY
1462		via the platform viewport, so you need both the genric layer and
1463		the viewport enabled. Currently only Chipidea/ARC based
1464		viewport is supported.
1465		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1466		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1467		If your ULPI phy needs a different reference clock than the
1468		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1469		the appropriate value in Hz.
1470
1471- MMC Support:
1472		The MMC controller on the Intel PXA is supported. To
1473		enable this define CONFIG_MMC. The MMC can be
1474		accessed from the boot prompt by mapping the device
1475		to physical memory similar to flash. Command line is
1476		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1477		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1478
1479		CONFIG_SH_MMCIF
1480		Support for Renesas on-chip MMCIF controller
1481
1482			CONFIG_SH_MMCIF_ADDR
1483			Define the base address of MMCIF registers
1484
1485			CONFIG_SH_MMCIF_CLK
1486			Define the clock frequency for MMCIF
1487
1488- USB Device Firmware Update (DFU) class support:
1489		CONFIG_DFU_FUNCTION
1490		This enables the USB portion of the DFU USB class
1491
1492		CONFIG_CMD_DFU
1493		This enables the command "dfu" which is used to have
1494		U-Boot create a DFU class device via USB.  This command
1495		requires that the "dfu_alt_info" environment variable be
1496		set and define the alt settings to expose to the host.
1497
1498		CONFIG_DFU_MMC
1499		This enables support for exposing (e)MMC devices via DFU.
1500
1501		CONFIG_DFU_NAND
1502		This enables support for exposing NAND devices via DFU.
1503
1504		CONFIG_DFU_RAM
1505		This enables support for exposing RAM via DFU.
1506		Note: DFU spec refer to non-volatile memory usage, but
1507		allow usages beyond the scope of spec - here RAM usage,
1508		one that would help mostly the developer.
1509
1510		CONFIG_SYS_DFU_DATA_BUF_SIZE
1511		Dfu transfer uses a buffer before writing data to the
1512		raw storage device. Make the size (in bytes) of this buffer
1513		configurable. The size of this buffer is also configurable
1514		through the "dfu_bufsiz" environment variable.
1515
1516		CONFIG_SYS_DFU_MAX_FILE_SIZE
1517		When updating files rather than the raw storage device,
1518		we use a static buffer to copy the file into and then write
1519		the buffer once we've been given the whole file.  Define
1520		this to the maximum filesize (in bytes) for the buffer.
1521		Default is 4 MiB if undefined.
1522
1523- Journaling Flash filesystem support:
1524		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1525		CONFIG_JFFS2_NAND_DEV
1526		Define these for a default partition on a NAND device
1527
1528		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1529		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1530		Define these for a default partition on a NOR device
1531
1532		CONFIG_SYS_JFFS_CUSTOM_PART
1533		Define this to create an own partition. You have to provide a
1534		function struct part_info* jffs2_part_info(int part_num)
1535
1536		If you define only one JFFS2 partition you may also want to
1537		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1538		to disable the command chpart. This is the default when you
1539		have not defined a custom partition
1540
1541- FAT(File Allocation Table) filesystem write function support:
1542		CONFIG_FAT_WRITE
1543
1544		Define this to enable support for saving memory data as a
1545		file in FAT formatted partition.
1546
1547		This will also enable the command "fatwrite" enabling the
1548		user to write files to FAT.
1549
1550CBFS (Coreboot Filesystem) support
1551		CONFIG_CMD_CBFS
1552
1553		Define this to enable support for reading from a Coreboot
1554		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1555		and cbfsload.
1556
1557- Keyboard Support:
1558		CONFIG_ISA_KEYBOARD
1559
1560		Define this to enable standard (PC-Style) keyboard
1561		support
1562
1563		CONFIG_I8042_KBD
1564		Standard PC keyboard driver with US (is default) and
1565		GERMAN key layout (switch via environment 'keymap=de') support.
1566		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1567		for cfb_console. Supports cursor blinking.
1568
1569		CONFIG_CROS_EC_KEYB
1570		Enables a Chrome OS keyboard using the CROS_EC interface.
1571		This uses CROS_EC to communicate with a second microcontroller
1572		which provides key scans on request.
1573
1574- Video support:
1575		CONFIG_VIDEO
1576
1577		Define this to enable video support (for output to
1578		video).
1579
1580		CONFIG_VIDEO_CT69000
1581
1582		Enable Chips & Technologies 69000 Video chip
1583
1584		CONFIG_VIDEO_SMI_LYNXEM
1585		Enable Silicon Motion SMI 712/710/810 Video chip. The
1586		video output is selected via environment 'videoout'
1587		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1588		assumed.
1589
1590		For the CT69000 and SMI_LYNXEM drivers, videomode is
1591		selected via environment 'videomode'. Two different ways
1592		are possible:
1593		- "videomode=num"   'num' is a standard LiLo mode numbers.
1594		Following standard modes are supported	(* is default):
1595
1596		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1597		-------------+---------------------------------------------
1598		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1599		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1600		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1601		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1602		-------------+---------------------------------------------
1603		(i.e. setenv videomode 317; saveenv; reset;)
1604
1605		- "videomode=bootargs" all the video parameters are parsed
1606		from the bootargs. (See drivers/video/videomodes.c)
1607
1608
1609		CONFIG_VIDEO_SED13806
1610		Enable Epson SED13806 driver. This driver supports 8bpp
1611		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1612		or CONFIG_VIDEO_SED13806_16BPP
1613
1614		CONFIG_FSL_DIU_FB
1615		Enable the Freescale DIU video driver.	Reference boards for
1616		SOCs that have a DIU should define this macro to enable DIU
1617		support, and should also define these other macros:
1618
1619			CONFIG_SYS_DIU_ADDR
1620			CONFIG_VIDEO
1621			CONFIG_CMD_BMP
1622			CONFIG_CFB_CONSOLE
1623			CONFIG_VIDEO_SW_CURSOR
1624			CONFIG_VGA_AS_SINGLE_DEVICE
1625			CONFIG_VIDEO_LOGO
1626			CONFIG_VIDEO_BMP_LOGO
1627
1628		The DIU driver will look for the 'video-mode' environment
1629		variable, and if defined, enable the DIU as a console during
1630		boot.  See the documentation file README.video for a
1631		description of this variable.
1632
1633		CONFIG_VIDEO_VGA
1634
1635		Enable the VGA video / BIOS for x86. The alternative if you
1636		are using coreboot is to use the coreboot frame buffer
1637		driver.
1638
1639
1640- Keyboard Support:
1641		CONFIG_KEYBOARD
1642
1643		Define this to enable a custom keyboard support.
1644		This simply calls drv_keyboard_init() which must be
1645		defined in your board-specific files.
1646		The only board using this so far is RBC823.
1647
1648- LCD Support:	CONFIG_LCD
1649
1650		Define this to enable LCD support (for output to LCD
1651		display); also select one of the supported displays
1652		by defining one of these:
1653
1654		CONFIG_ATMEL_LCD:
1655
1656			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1657
1658		CONFIG_NEC_NL6448AC33:
1659
1660			NEC NL6448AC33-18. Active, color, single scan.
1661
1662		CONFIG_NEC_NL6448BC20
1663
1664			NEC NL6448BC20-08. 6.5", 640x480.
1665			Active, color, single scan.
1666
1667		CONFIG_NEC_NL6448BC33_54
1668
1669			NEC NL6448BC33-54. 10.4", 640x480.
1670			Active, color, single scan.
1671
1672		CONFIG_SHARP_16x9
1673
1674			Sharp 320x240. Active, color, single scan.
1675			It isn't 16x9, and I am not sure what it is.
1676
1677		CONFIG_SHARP_LQ64D341
1678
1679			Sharp LQ64D341 display, 640x480.
1680			Active, color, single scan.
1681
1682		CONFIG_HLD1045
1683
1684			HLD1045 display, 640x480.
1685			Active, color, single scan.
1686
1687		CONFIG_OPTREX_BW
1688
1689			Optrex	 CBL50840-2 NF-FW 99 22 M5
1690			or
1691			Hitachi	 LMG6912RPFC-00T
1692			or
1693			Hitachi	 SP14Q002
1694
1695			320x240. Black & white.
1696
1697		Normally display is black on white background; define
1698		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1699
1700		CONFIG_LCD_ALIGNMENT
1701
1702		Normally the LCD is page-aligned (tyically 4KB). If this is
1703		defined then the LCD will be aligned to this value instead.
1704		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1705		here, since it is cheaper to change data cache settings on
1706		a per-section basis.
1707
1708		CONFIG_CONSOLE_SCROLL_LINES
1709
1710		When the console need to be scrolled, this is the number of
1711		lines to scroll by. It defaults to 1. Increasing this makes
1712		the console jump but can help speed up operation when scrolling
1713		is slow.
1714
1715		CONFIG_LCD_BMP_RLE8
1716
1717		Support drawing of RLE8-compressed bitmaps on the LCD.
1718
1719		CONFIG_I2C_EDID
1720
1721		Enables an 'i2c edid' command which can read EDID
1722		information over I2C from an attached LCD display.
1723
1724- Splash Screen Support: CONFIG_SPLASH_SCREEN
1725
1726		If this option is set, the environment is checked for
1727		a variable "splashimage". If found, the usual display
1728		of logo, copyright and system information on the LCD
1729		is suppressed and the BMP image at the address
1730		specified in "splashimage" is loaded instead. The
1731		console is redirected to the "nulldev", too. This
1732		allows for a "silent" boot where a splash screen is
1733		loaded very quickly after power-on.
1734
1735		CONFIG_SPLASHIMAGE_GUARD
1736
1737		If this option is set, then U-Boot will prevent the environment
1738		variable "splashimage" from being set to a problematic address
1739		(see README.displaying-bmps and README.arm-unaligned-accesses).
1740		This option is useful for targets where, due to alignment
1741		restrictions, an improperly aligned BMP image will cause a data
1742		abort. If you think you will not have problems with unaligned
1743		accesses (for example because your toolchain prevents them)
1744		there is no need to set this option.
1745
1746		CONFIG_SPLASH_SCREEN_ALIGN
1747
1748		If this option is set the splash image can be freely positioned
1749		on the screen. Environment variable "splashpos" specifies the
1750		position as "x,y". If a positive number is given it is used as
1751		number of pixel from left/top. If a negative number is given it
1752		is used as number of pixel from right/bottom. You can also
1753		specify 'm' for centering the image.
1754
1755		Example:
1756		setenv splashpos m,m
1757			=> image at center of screen
1758
1759		setenv splashpos 30,20
1760			=> image at x = 30 and y = 20
1761
1762		setenv splashpos -10,m
1763			=> vertically centered image
1764			   at x = dspWidth - bmpWidth - 9
1765
1766- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1767
1768		If this option is set, additionally to standard BMP
1769		images, gzipped BMP images can be displayed via the
1770		splashscreen support or the bmp command.
1771
1772- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1773
1774		If this option is set, 8-bit RLE compressed BMP images
1775		can be displayed via the splashscreen support or the
1776		bmp command.
1777
1778- Do compresssing for memory range:
1779		CONFIG_CMD_ZIP
1780
1781		If this option is set, it would use zlib deflate method
1782		to compress the specified memory at its best effort.
1783
1784- Compression support:
1785		CONFIG_GZIP
1786
1787		Enabled by default to support gzip compressed images.
1788
1789		CONFIG_BZIP2
1790
1791		If this option is set, support for bzip2 compressed
1792		images is included. If not, only uncompressed and gzip
1793		compressed images are supported.
1794
1795		NOTE: the bzip2 algorithm requires a lot of RAM, so
1796		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1797		be at least 4MB.
1798
1799		CONFIG_LZMA
1800
1801		If this option is set, support for lzma compressed
1802		images is included.
1803
1804		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1805		requires an amount of dynamic memory that is given by the
1806		formula:
1807
1808			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1809
1810		Where lc and lp stand for, respectively, Literal context bits
1811		and Literal pos bits.
1812
1813		This value is upper-bounded by 14MB in the worst case. Anyway,
1814		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1815		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1816		a very small buffer.
1817
1818		Use the lzmainfo tool to determinate the lc and lp values and
1819		then calculate the amount of needed dynamic memory (ensuring
1820		the appropriate CONFIG_SYS_MALLOC_LEN value).
1821
1822		CONFIG_LZO
1823
1824		If this option is set, support for LZO compressed images
1825		is included.
1826
1827- MII/PHY support:
1828		CONFIG_PHY_ADDR
1829
1830		The address of PHY on MII bus.
1831
1832		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1833
1834		The clock frequency of the MII bus
1835
1836		CONFIG_PHY_GIGE
1837
1838		If this option is set, support for speed/duplex
1839		detection of gigabit PHY is included.
1840
1841		CONFIG_PHY_RESET_DELAY
1842
1843		Some PHY like Intel LXT971A need extra delay after
1844		reset before any MII register access is possible.
1845		For such PHY, set this option to the usec delay
1846		required. (minimum 300usec for LXT971A)
1847
1848		CONFIG_PHY_CMD_DELAY (ppc4xx)
1849
1850		Some PHY like Intel LXT971A need extra delay after
1851		command issued before MII status register can be read
1852
1853- Ethernet address:
1854		CONFIG_ETHADDR
1855		CONFIG_ETH1ADDR
1856		CONFIG_ETH2ADDR
1857		CONFIG_ETH3ADDR
1858		CONFIG_ETH4ADDR
1859		CONFIG_ETH5ADDR
1860
1861		Define a default value for Ethernet address to use
1862		for the respective Ethernet interface, in case this
1863		is not determined automatically.
1864
1865- IP address:
1866		CONFIG_IPADDR
1867
1868		Define a default value for the IP address to use for
1869		the default Ethernet interface, in case this is not
1870		determined through e.g. bootp.
1871		(Environment variable "ipaddr")
1872
1873- Server IP address:
1874		CONFIG_SERVERIP
1875
1876		Defines a default value for the IP address of a TFTP
1877		server to contact when using the "tftboot" command.
1878		(Environment variable "serverip")
1879
1880		CONFIG_KEEP_SERVERADDR
1881
1882		Keeps the server's MAC address, in the env 'serveraddr'
1883		for passing to bootargs (like Linux's netconsole option)
1884
1885- Gateway IP address:
1886		CONFIG_GATEWAYIP
1887
1888		Defines a default value for the IP address of the
1889		default router where packets to other networks are
1890		sent to.
1891		(Environment variable "gatewayip")
1892
1893- Subnet mask:
1894		CONFIG_NETMASK
1895
1896		Defines a default value for the subnet mask (or
1897		routing prefix) which is used to determine if an IP
1898		address belongs to the local subnet or needs to be
1899		forwarded through a router.
1900		(Environment variable "netmask")
1901
1902- Multicast TFTP Mode:
1903		CONFIG_MCAST_TFTP
1904
1905		Defines whether you want to support multicast TFTP as per
1906		rfc-2090; for example to work with atftp.  Lets lots of targets
1907		tftp down the same boot image concurrently.  Note: the Ethernet
1908		driver in use must provide a function: mcast() to join/leave a
1909		multicast group.
1910
1911- BOOTP Recovery Mode:
1912		CONFIG_BOOTP_RANDOM_DELAY
1913
1914		If you have many targets in a network that try to
1915		boot using BOOTP, you may want to avoid that all
1916		systems send out BOOTP requests at precisely the same
1917		moment (which would happen for instance at recovery
1918		from a power failure, when all systems will try to
1919		boot, thus flooding the BOOTP server. Defining
1920		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1921		inserted before sending out BOOTP requests. The
1922		following delays are inserted then:
1923
1924		1st BOOTP request:	delay 0 ... 1 sec
1925		2nd BOOTP request:	delay 0 ... 2 sec
1926		3rd BOOTP request:	delay 0 ... 4 sec
1927		4th and following
1928		BOOTP requests:		delay 0 ... 8 sec
1929
1930- DHCP Advanced Options:
1931		You can fine tune the DHCP functionality by defining
1932		CONFIG_BOOTP_* symbols:
1933
1934		CONFIG_BOOTP_SUBNETMASK
1935		CONFIG_BOOTP_GATEWAY
1936		CONFIG_BOOTP_HOSTNAME
1937		CONFIG_BOOTP_NISDOMAIN
1938		CONFIG_BOOTP_BOOTPATH
1939		CONFIG_BOOTP_BOOTFILESIZE
1940		CONFIG_BOOTP_DNS
1941		CONFIG_BOOTP_DNS2
1942		CONFIG_BOOTP_SEND_HOSTNAME
1943		CONFIG_BOOTP_NTPSERVER
1944		CONFIG_BOOTP_TIMEOFFSET
1945		CONFIG_BOOTP_VENDOREX
1946		CONFIG_BOOTP_MAY_FAIL
1947
1948		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1949		environment variable, not the BOOTP server.
1950
1951		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1952		after the configured retry count, the call will fail
1953		instead of starting over.  This can be used to fail over
1954		to Link-local IP address configuration if the DHCP server
1955		is not available.
1956
1957		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1958		serverip from a DHCP server, it is possible that more
1959		than one DNS serverip is offered to the client.
1960		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1961		serverip will be stored in the additional environment
1962		variable "dnsip2". The first DNS serverip is always
1963		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1964		is defined.
1965
1966		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1967		to do a dynamic update of a DNS server. To do this, they
1968		need the hostname of the DHCP requester.
1969		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1970		of the "hostname" environment variable is passed as
1971		option 12 to the DHCP server.
1972
1973		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1974
1975		A 32bit value in microseconds for a delay between
1976		receiving a "DHCP Offer" and sending the "DHCP Request".
1977		This fixes a problem with certain DHCP servers that don't
1978		respond 100% of the time to a "DHCP request". E.g. On an
1979		AT91RM9200 processor running at 180MHz, this delay needed
1980		to be *at least* 15,000 usec before a Windows Server 2003
1981		DHCP server would reply 100% of the time. I recommend at
1982		least 50,000 usec to be safe. The alternative is to hope
1983		that one of the retries will be successful but note that
1984		the DHCP timeout and retry process takes a longer than
1985		this delay.
1986
1987 - Link-local IP address negotiation:
1988		Negotiate with other link-local clients on the local network
1989		for an address that doesn't require explicit configuration.
1990		This is especially useful if a DHCP server cannot be guaranteed
1991		to exist in all environments that the device must operate.
1992
1993		See doc/README.link-local for more information.
1994
1995 - CDP Options:
1996		CONFIG_CDP_DEVICE_ID
1997
1998		The device id used in CDP trigger frames.
1999
2000		CONFIG_CDP_DEVICE_ID_PREFIX
2001
2002		A two character string which is prefixed to the MAC address
2003		of the device.
2004
2005		CONFIG_CDP_PORT_ID
2006
2007		A printf format string which contains the ascii name of
2008		the port. Normally is set to "eth%d" which sets
2009		eth0 for the first Ethernet, eth1 for the second etc.
2010
2011		CONFIG_CDP_CAPABILITIES
2012
2013		A 32bit integer which indicates the device capabilities;
2014		0x00000010 for a normal host which does not forwards.
2015
2016		CONFIG_CDP_VERSION
2017
2018		An ascii string containing the version of the software.
2019
2020		CONFIG_CDP_PLATFORM
2021
2022		An ascii string containing the name of the platform.
2023
2024		CONFIG_CDP_TRIGGER
2025
2026		A 32bit integer sent on the trigger.
2027
2028		CONFIG_CDP_POWER_CONSUMPTION
2029
2030		A 16bit integer containing the power consumption of the
2031		device in .1 of milliwatts.
2032
2033		CONFIG_CDP_APPLIANCE_VLAN_TYPE
2034
2035		A byte containing the id of the VLAN.
2036
2037- Status LED:	CONFIG_STATUS_LED
2038
2039		Several configurations allow to display the current
2040		status using a LED. For instance, the LED will blink
2041		fast while running U-Boot code, stop blinking as
2042		soon as a reply to a BOOTP request was received, and
2043		start blinking slow once the Linux kernel is running
2044		(supported by a status LED driver in the Linux
2045		kernel). Defining CONFIG_STATUS_LED enables this
2046		feature in U-Boot.
2047
2048		Additional options:
2049
2050		CONFIG_GPIO_LED
2051		The status LED can be connected to a GPIO pin.
2052		In such cases, the gpio_led driver can be used as a
2053		status LED backend implementation. Define CONFIG_GPIO_LED
2054		to include the gpio_led driver in the U-Boot binary.
2055
2056		CONFIG_GPIO_LED_INVERTED_TABLE
2057		Some GPIO connected LEDs may have inverted polarity in which
2058		case the GPIO high value corresponds to LED off state and
2059		GPIO low value corresponds to LED on state.
2060		In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
2061		with a list of GPIO LEDs that have inverted polarity.
2062
2063- CAN Support:	CONFIG_CAN_DRIVER
2064
2065		Defining CONFIG_CAN_DRIVER enables CAN driver support
2066		on those systems that support this (optional)
2067		feature, like the TQM8xxL modules.
2068
2069- I2C Support:	CONFIG_SYS_I2C
2070
2071		This enable the NEW i2c subsystem, and will allow you to use
2072		i2c commands at the u-boot command line (as long as you set
2073		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
2074		based realtime clock chips or other i2c devices. See
2075		common/cmd_i2c.c for a description of the command line
2076		interface.
2077
2078		ported i2c driver to the new framework:
2079		- drivers/i2c/soft_i2c.c:
2080		  - activate first bus with CONFIG_SYS_I2C_SOFT define
2081		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
2082		    for defining speed and slave address
2083		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
2084		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
2085		    for defining speed and slave address
2086		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
2087		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
2088		    for defining speed and slave address
2089		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
2090		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
2091		    for defining speed and slave address
2092
2093		- drivers/i2c/fsl_i2c.c:
2094		  - activate i2c driver with CONFIG_SYS_I2C_FSL
2095		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
2096		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
2097		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
2098		    bus.
2099		  - If your board supports a second fsl i2c bus, define
2100		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
2101		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
2102		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
2103		    second bus.
2104
2105		- drivers/i2c/tegra_i2c.c:
2106		  - activate this driver with CONFIG_SYS_I2C_TEGRA
2107		  - This driver adds 4 i2c buses with a fix speed from
2108		    100000 and the slave addr 0!
2109
2110		- drivers/i2c/ppc4xx_i2c.c
2111		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
2112		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
2113		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
2114
2115		- drivers/i2c/i2c_mxc.c
2116		  - activate this driver with CONFIG_SYS_I2C_MXC
2117		  - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
2118		  - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
2119		  - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
2120		  - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
2121		  - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
2122		  - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
2123		If thoses defines are not set, default value is 100000
2124		for speed, and 0 for slave.
2125
2126		- drivers/i2c/rcar_i2c.c:
2127		  - activate this driver with CONFIG_SYS_I2C_RCAR
2128		  - This driver adds 4 i2c buses
2129
2130		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
2131		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
2132		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
2133		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
2134		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
2135		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
2136		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
2137		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
2138		  - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
2139
2140		- drivers/i2c/sh_i2c.c:
2141		  - activate this driver with CONFIG_SYS_I2C_SH
2142		  - This driver adds from 2 to 5 i2c buses
2143
2144		  - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
2145		  - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
2146		  - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
2147		  - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
2148		  - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
2149		  - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
2150		  - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
2151		  - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
2152		  - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
2153		  - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
2154		  - CONFIG_SYS_I2C_SH_BASE5 for setting the register channel 5
2155		  - CONFIG_SYS_I2C_SH_SPEED5 for for the speed channel 5
2156		  - CONFIF_SYS_I2C_SH_NUM_CONTROLLERS for nummber of i2c buses
2157
2158		- drivers/i2c/omap24xx_i2c.c
2159		  - activate this driver with CONFIG_SYS_I2C_OMAP24XX
2160		  - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
2161		  - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
2162		  - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
2163		  - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
2164		  - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
2165		  - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
2166		  - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
2167		  - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
2168		  - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
2169		  - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
2170
2171		- drivers/i2c/zynq_i2c.c
2172		  - activate this driver with CONFIG_SYS_I2C_ZYNQ
2173		  - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
2174		  - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
2175
2176		- drivers/i2c/s3c24x0_i2c.c:
2177		  - activate this driver with CONFIG_SYS_I2C_S3C24X0
2178		  - This driver adds i2c buses (11 for Exynos5250, Exynos5420
2179		    9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
2180		    with a fix speed from 100000 and the slave addr 0!
2181
2182		additional defines:
2183
2184		CONFIG_SYS_NUM_I2C_BUSES
2185		Hold the number of i2c busses you want to use. If you
2186		don't use/have i2c muxes on your i2c bus, this
2187		is equal to CONFIG_SYS_NUM_I2C_ADAPTERS, and you can
2188		omit this define.
2189
2190		CONFIG_SYS_I2C_DIRECT_BUS
2191		define this, if you don't use i2c muxes on your hardware.
2192		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2193		omit this define.
2194
2195		CONFIG_SYS_I2C_MAX_HOPS
2196		define how many muxes are maximal consecutively connected
2197		on one i2c bus. If you not use i2c muxes, omit this
2198		define.
2199
2200		CONFIG_SYS_I2C_BUSES
2201		hold a list of busses you want to use, only used if
2202		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2203		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2204		CONFIG_SYS_NUM_I2C_BUSES = 9:
2205
2206		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
2207					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2208					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2209					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2210					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2211					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2212					{1, {I2C_NULL_HOP}}, \
2213					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2214					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2215					}
2216
2217		which defines
2218			bus 0 on adapter 0 without a mux
2219			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2220			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2221			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2222			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2223			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2224			bus 6 on adapter 1 without a mux
2225			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2226			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2227
2228		If you do not have i2c muxes on your board, omit this define.
2229
2230- Legacy I2C Support:	CONFIG_HARD_I2C
2231
2232		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2233		provides the following compelling advantages:
2234
2235		- more than one i2c adapter is usable
2236		- approved multibus support
2237		- better i2c mux support
2238
2239		** Please consider updating your I2C driver now. **
2240
2241		These enable legacy I2C serial bus commands. Defining
2242		CONFIG_HARD_I2C will include the appropriate I2C driver
2243		for the selected CPU.
2244
2245		This will allow you to use i2c commands at the u-boot
2246		command line (as long as you set CONFIG_CMD_I2C in
2247		CONFIG_COMMANDS) and communicate with i2c based realtime
2248		clock chips. See common/cmd_i2c.c for a description of the
2249		command line interface.
2250
2251		CONFIG_HARD_I2C selects a hardware I2C controller.
2252
2253		There are several other quantities that must also be
2254		defined when you define CONFIG_HARD_I2C.
2255
2256		In both cases you will need to define CONFIG_SYS_I2C_SPEED
2257		to be the frequency (in Hz) at which you wish your i2c bus
2258		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2259		the CPU's i2c node address).
2260
2261		Now, the u-boot i2c code for the mpc8xx
2262		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2263		and so its address should therefore be cleared to 0 (See,
2264		eg, MPC823e User's Manual p.16-473). So, set
2265		CONFIG_SYS_I2C_SLAVE to 0.
2266
2267		CONFIG_SYS_I2C_INIT_MPC5XXX
2268
2269		When a board is reset during an i2c bus transfer
2270		chips might think that the current transfer is still
2271		in progress.  Reset the slave devices by sending start
2272		commands until the slave device responds.
2273
2274		That's all that's required for CONFIG_HARD_I2C.
2275
2276		If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2277		then the following macros need to be defined (examples are
2278		from include/configs/lwmon.h):
2279
2280		I2C_INIT
2281
2282		(Optional). Any commands necessary to enable the I2C
2283		controller or configure ports.
2284
2285		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2286
2287		I2C_PORT
2288
2289		(Only for MPC8260 CPU). The I/O port to use (the code
2290		assumes both bits are on the same port). Valid values
2291		are 0..3 for ports A..D.
2292
2293		I2C_ACTIVE
2294
2295		The code necessary to make the I2C data line active
2296		(driven).  If the data line is open collector, this
2297		define can be null.
2298
2299		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2300
2301		I2C_TRISTATE
2302
2303		The code necessary to make the I2C data line tri-stated
2304		(inactive).  If the data line is open collector, this
2305		define can be null.
2306
2307		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2308
2309		I2C_READ
2310
2311		Code that returns true if the I2C data line is high,
2312		false if it is low.
2313
2314		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2315
2316		I2C_SDA(bit)
2317
2318		If <bit> is true, sets the I2C data line high. If it
2319		is false, it clears it (low).
2320
2321		eg: #define I2C_SDA(bit) \
2322			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2323			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2324
2325		I2C_SCL(bit)
2326
2327		If <bit> is true, sets the I2C clock line high. If it
2328		is false, it clears it (low).
2329
2330		eg: #define I2C_SCL(bit) \
2331			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2332			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2333
2334		I2C_DELAY
2335
2336		This delay is invoked four times per clock cycle so this
2337		controls the rate of data transfer.  The data rate thus
2338		is 1 / (I2C_DELAY * 4). Often defined to be something
2339		like:
2340
2341		#define I2C_DELAY  udelay(2)
2342
2343		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2344
2345		If your arch supports the generic GPIO framework (asm/gpio.h),
2346		then you may alternatively define the two GPIOs that are to be
2347		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2348		have GPIO-based defaults assigned to them as appropriate.
2349
2350		You should define these to the GPIO value as given directly to
2351		the generic GPIO functions.
2352
2353		CONFIG_SYS_I2C_INIT_BOARD
2354
2355		When a board is reset during an i2c bus transfer
2356		chips might think that the current transfer is still
2357		in progress. On some boards it is possible to access
2358		the i2c SCLK line directly, either by using the
2359		processor pin as a GPIO or by having a second pin
2360		connected to the bus. If this option is defined a
2361		custom i2c_init_board() routine in boards/xxx/board.c
2362		is run early in the boot sequence.
2363
2364		CONFIG_SYS_I2C_BOARD_LATE_INIT
2365
2366		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2367		defined a custom i2c_board_late_init() routine in
2368		boards/xxx/board.c is run AFTER the operations in i2c_init()
2369		is completed. This callpoint can be used to unreset i2c bus
2370		using CPU i2c controller register accesses for CPUs whose i2c
2371		controller provide such a method. It is called at the end of
2372		i2c_init() to allow i2c_init operations to setup the i2c bus
2373		controller on the CPU (e.g. setting bus speed & slave address).
2374
2375		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2376
2377		This option enables configuration of bi_iic_fast[] flags
2378		in u-boot bd_info structure based on u-boot environment
2379		variable "i2cfast". (see also i2cfast)
2380
2381		CONFIG_I2C_MULTI_BUS
2382
2383		This option allows the use of multiple I2C buses, each of which
2384		must have a controller.	 At any point in time, only one bus is
2385		active.	 To switch to a different bus, use the 'i2c dev' command.
2386		Note that bus numbering is zero-based.
2387
2388		CONFIG_SYS_I2C_NOPROBES
2389
2390		This option specifies a list of I2C devices that will be skipped
2391		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2392		is set, specify a list of bus-device pairs.  Otherwise, specify
2393		a 1D array of device addresses
2394
2395		e.g.
2396			#undef	CONFIG_I2C_MULTI_BUS
2397			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2398
2399		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2400
2401			#define CONFIG_I2C_MULTI_BUS
2402			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2403
2404		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2405
2406		CONFIG_SYS_SPD_BUS_NUM
2407
2408		If defined, then this indicates the I2C bus number for DDR SPD.
2409		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2410
2411		CONFIG_SYS_RTC_BUS_NUM
2412
2413		If defined, then this indicates the I2C bus number for the RTC.
2414		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2415
2416		CONFIG_SYS_DTT_BUS_NUM
2417
2418		If defined, then this indicates the I2C bus number for the DTT.
2419		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2420
2421		CONFIG_SYS_I2C_DTT_ADDR:
2422
2423		If defined, specifies the I2C address of the DTT device.
2424		If not defined, then U-Boot uses predefined value for
2425		specified DTT device.
2426
2427		CONFIG_SOFT_I2C_READ_REPEATED_START
2428
2429		defining this will force the i2c_read() function in
2430		the soft_i2c driver to perform an I2C repeated start
2431		between writing the address pointer and reading the
2432		data.  If this define is omitted the default behaviour
2433		of doing a stop-start sequence will be used.  Most I2C
2434		devices can use either method, but some require one or
2435		the other.
2436
2437- SPI Support:	CONFIG_SPI
2438
2439		Enables SPI driver (so far only tested with
2440		SPI EEPROM, also an instance works with Crystal A/D and
2441		D/As on the SACSng board)
2442
2443		CONFIG_SH_SPI
2444
2445		Enables the driver for SPI controller on SuperH. Currently
2446		only SH7757 is supported.
2447
2448		CONFIG_SPI_X
2449
2450		Enables extended (16-bit) SPI EEPROM addressing.
2451		(symmetrical to CONFIG_I2C_X)
2452
2453		CONFIG_SOFT_SPI
2454
2455		Enables a software (bit-bang) SPI driver rather than
2456		using hardware support. This is a general purpose
2457		driver that only requires three general I/O port pins
2458		(two outputs, one input) to function. If this is
2459		defined, the board configuration must define several
2460		SPI configuration items (port pins to use, etc). For
2461		an example, see include/configs/sacsng.h.
2462
2463		CONFIG_HARD_SPI
2464
2465		Enables a hardware SPI driver for general-purpose reads
2466		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2467		must define a list of chip-select function pointers.
2468		Currently supported on some MPC8xxx processors.	 For an
2469		example, see include/configs/mpc8349emds.h.
2470
2471		CONFIG_MXC_SPI
2472
2473		Enables the driver for the SPI controllers on i.MX and MXC
2474		SoCs. Currently i.MX31/35/51 are supported.
2475
2476- FPGA Support: CONFIG_FPGA
2477
2478		Enables FPGA subsystem.
2479
2480		CONFIG_FPGA_<vendor>
2481
2482		Enables support for specific chip vendors.
2483		(ALTERA, XILINX)
2484
2485		CONFIG_FPGA_<family>
2486
2487		Enables support for FPGA family.
2488		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2489
2490		CONFIG_FPGA_COUNT
2491
2492		Specify the number of FPGA devices to support.
2493
2494		CONFIG_SYS_FPGA_PROG_FEEDBACK
2495
2496		Enable printing of hash marks during FPGA configuration.
2497
2498		CONFIG_SYS_FPGA_CHECK_BUSY
2499
2500		Enable checks on FPGA configuration interface busy
2501		status by the configuration function. This option
2502		will require a board or device specific function to
2503		be written.
2504
2505		CONFIG_FPGA_DELAY
2506
2507		If defined, a function that provides delays in the FPGA
2508		configuration driver.
2509
2510		CONFIG_SYS_FPGA_CHECK_CTRLC
2511		Allow Control-C to interrupt FPGA configuration
2512
2513		CONFIG_SYS_FPGA_CHECK_ERROR
2514
2515		Check for configuration errors during FPGA bitfile
2516		loading. For example, abort during Virtex II
2517		configuration if the INIT_B line goes low (which
2518		indicated a CRC error).
2519
2520		CONFIG_SYS_FPGA_WAIT_INIT
2521
2522		Maximum time to wait for the INIT_B line to deassert
2523		after PROB_B has been deasserted during a Virtex II
2524		FPGA configuration sequence. The default time is 500
2525		ms.
2526
2527		CONFIG_SYS_FPGA_WAIT_BUSY
2528
2529		Maximum time to wait for BUSY to deassert during
2530		Virtex II FPGA configuration. The default is 5 ms.
2531
2532		CONFIG_SYS_FPGA_WAIT_CONFIG
2533
2534		Time to wait after FPGA configuration. The default is
2535		200 ms.
2536
2537- Configuration Management:
2538		CONFIG_IDENT_STRING
2539
2540		If defined, this string will be added to the U-Boot
2541		version information (U_BOOT_VERSION)
2542
2543- Vendor Parameter Protection:
2544
2545		U-Boot considers the values of the environment
2546		variables "serial#" (Board Serial Number) and
2547		"ethaddr" (Ethernet Address) to be parameters that
2548		are set once by the board vendor / manufacturer, and
2549		protects these variables from casual modification by
2550		the user. Once set, these variables are read-only,
2551		and write or delete attempts are rejected. You can
2552		change this behaviour:
2553
2554		If CONFIG_ENV_OVERWRITE is #defined in your config
2555		file, the write protection for vendor parameters is
2556		completely disabled. Anybody can change or delete
2557		these parameters.
2558
2559		Alternatively, if you #define _both_ CONFIG_ETHADDR
2560		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2561		Ethernet address is installed in the environment,
2562		which can be changed exactly ONCE by the user. [The
2563		serial# is unaffected by this, i. e. it remains
2564		read-only.]
2565
2566		The same can be accomplished in a more flexible way
2567		for any variable by configuring the type of access
2568		to allow for those variables in the ".flags" variable
2569		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2570
2571- Protected RAM:
2572		CONFIG_PRAM
2573
2574		Define this variable to enable the reservation of
2575		"protected RAM", i. e. RAM which is not overwritten
2576		by U-Boot. Define CONFIG_PRAM to hold the number of
2577		kB you want to reserve for pRAM. You can overwrite
2578		this default value by defining an environment
2579		variable "pram" to the number of kB you want to
2580		reserve. Note that the board info structure will
2581		still show the full amount of RAM. If pRAM is
2582		reserved, a new environment variable "mem" will
2583		automatically be defined to hold the amount of
2584		remaining RAM in a form that can be passed as boot
2585		argument to Linux, for instance like that:
2586
2587			setenv bootargs ... mem=\${mem}
2588			saveenv
2589
2590		This way you can tell Linux not to use this memory,
2591		either, which results in a memory region that will
2592		not be affected by reboots.
2593
2594		*WARNING* If your board configuration uses automatic
2595		detection of the RAM size, you must make sure that
2596		this memory test is non-destructive. So far, the
2597		following board configurations are known to be
2598		"pRAM-clean":
2599
2600			IVMS8, IVML24, SPD8xx, TQM8xxL,
2601			HERMES, IP860, RPXlite, LWMON,
2602			FLAGADM, TQM8260
2603
2604- Access to physical memory region (> 4GB)
2605		Some basic support is provided for operations on memory not
2606		normally accessible to U-Boot - e.g. some architectures
2607		support access to more than 4GB of memory on 32-bit
2608		machines using physical address extension or similar.
2609		Define CONFIG_PHYSMEM to access this basic support, which
2610		currently only supports clearing the memory.
2611
2612- Error Recovery:
2613		CONFIG_PANIC_HANG
2614
2615		Define this variable to stop the system in case of a
2616		fatal error, so that you have to reset it manually.
2617		This is probably NOT a good idea for an embedded
2618		system where you want the system to reboot
2619		automatically as fast as possible, but it may be
2620		useful during development since you can try to debug
2621		the conditions that lead to the situation.
2622
2623		CONFIG_NET_RETRY_COUNT
2624
2625		This variable defines the number of retries for
2626		network operations like ARP, RARP, TFTP, or BOOTP
2627		before giving up the operation. If not defined, a
2628		default value of 5 is used.
2629
2630		CONFIG_ARP_TIMEOUT
2631
2632		Timeout waiting for an ARP reply in milliseconds.
2633
2634		CONFIG_NFS_TIMEOUT
2635
2636		Timeout in milliseconds used in NFS protocol.
2637		If you encounter "ERROR: Cannot umount" in nfs command,
2638		try longer timeout such as
2639		#define CONFIG_NFS_TIMEOUT 10000UL
2640
2641- Command Interpreter:
2642		CONFIG_AUTO_COMPLETE
2643
2644		Enable auto completion of commands using TAB.
2645
2646		Note that this feature has NOT been implemented yet
2647		for the "hush" shell.
2648
2649
2650		CONFIG_SYS_HUSH_PARSER
2651
2652		Define this variable to enable the "hush" shell (from
2653		Busybox) as command line interpreter, thus enabling
2654		powerful command line syntax like
2655		if...then...else...fi conditionals or `&&' and '||'
2656		constructs ("shell scripts").
2657
2658		If undefined, you get the old, much simpler behaviour
2659		with a somewhat smaller memory footprint.
2660
2661
2662		CONFIG_SYS_PROMPT_HUSH_PS2
2663
2664		This defines the secondary prompt string, which is
2665		printed when the command interpreter needs more input
2666		to complete a command. Usually "> ".
2667
2668	Note:
2669
2670		In the current implementation, the local variables
2671		space and global environment variables space are
2672		separated. Local variables are those you define by
2673		simply typing `name=value'. To access a local
2674		variable later on, you have write `$name' or
2675		`${name}'; to execute the contents of a variable
2676		directly type `$name' at the command prompt.
2677
2678		Global environment variables are those you use
2679		setenv/printenv to work with. To run a command stored
2680		in such a variable, you need to use the run command,
2681		and you must not use the '$' sign to access them.
2682
2683		To store commands and special characters in a
2684		variable, please use double quotation marks
2685		surrounding the whole text of the variable, instead
2686		of the backslashes before semicolons and special
2687		symbols.
2688
2689- Commandline Editing and History:
2690		CONFIG_CMDLINE_EDITING
2691
2692		Enable editing and History functions for interactive
2693		commandline input operations
2694
2695- Default Environment:
2696		CONFIG_EXTRA_ENV_SETTINGS
2697
2698		Define this to contain any number of null terminated
2699		strings (variable = value pairs) that will be part of
2700		the default environment compiled into the boot image.
2701
2702		For example, place something like this in your
2703		board's config file:
2704
2705		#define CONFIG_EXTRA_ENV_SETTINGS \
2706			"myvar1=value1\0" \
2707			"myvar2=value2\0"
2708
2709		Warning: This method is based on knowledge about the
2710		internal format how the environment is stored by the
2711		U-Boot code. This is NOT an official, exported
2712		interface! Although it is unlikely that this format
2713		will change soon, there is no guarantee either.
2714		You better know what you are doing here.
2715
2716		Note: overly (ab)use of the default environment is
2717		discouraged. Make sure to check other ways to preset
2718		the environment like the "source" command or the
2719		boot command first.
2720
2721		CONFIG_ENV_VARS_UBOOT_CONFIG
2722
2723		Define this in order to add variables describing the
2724		U-Boot build configuration to the default environment.
2725		These will be named arch, cpu, board, vendor, and soc.
2726
2727		Enabling this option will cause the following to be defined:
2728
2729		- CONFIG_SYS_ARCH
2730		- CONFIG_SYS_CPU
2731		- CONFIG_SYS_BOARD
2732		- CONFIG_SYS_VENDOR
2733		- CONFIG_SYS_SOC
2734
2735		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2736
2737		Define this in order to add variables describing certain
2738		run-time determined information about the hardware to the
2739		environment.  These will be named board_name, board_rev.
2740
2741		CONFIG_DELAY_ENVIRONMENT
2742
2743		Normally the environment is loaded when the board is
2744		intialised so that it is available to U-Boot. This inhibits
2745		that so that the environment is not available until
2746		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2747		this is instead controlled by the value of
2748		/config/load-environment.
2749
2750- DataFlash Support:
2751		CONFIG_HAS_DATAFLASH
2752
2753		Defining this option enables DataFlash features and
2754		allows to read/write in Dataflash via the standard
2755		commands cp, md...
2756
2757- Serial Flash support
2758		CONFIG_CMD_SF
2759
2760		Defining this option enables SPI flash commands
2761		'sf probe/read/write/erase/update'.
2762
2763		Usage requires an initial 'probe' to define the serial
2764		flash parameters, followed by read/write/erase/update
2765		commands.
2766
2767		The following defaults may be provided by the platform
2768		to handle the common case when only a single serial
2769		flash is present on the system.
2770
2771		CONFIG_SF_DEFAULT_BUS		Bus identifier
2772		CONFIG_SF_DEFAULT_CS		Chip-select
2773		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2774		CONFIG_SF_DEFAULT_SPEED		in Hz
2775
2776		CONFIG_CMD_SF_TEST
2777
2778		Define this option to include a destructive SPI flash
2779		test ('sf test').
2780
2781		CONFIG_SPI_FLASH_BAR		Ban/Extended Addr Reg
2782
2783		Define this option to use the Bank addr/Extended addr
2784		support on SPI flashes which has size > 16Mbytes.
2785
2786		CONFIG_SF_DUAL_FLASH		Dual flash memories
2787
2788		Define this option to use dual flash support where two flash
2789		memories can be connected with a given cs line.
2790		currently Xilinx Zynq qspi support these type of connections.
2791
2792- SystemACE Support:
2793		CONFIG_SYSTEMACE
2794
2795		Adding this option adds support for Xilinx SystemACE
2796		chips attached via some sort of local bus. The address
2797		of the chip must also be defined in the
2798		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2799
2800		#define CONFIG_SYSTEMACE
2801		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2802
2803		When SystemACE support is added, the "ace" device type
2804		becomes available to the fat commands, i.e. fatls.
2805
2806- TFTP Fixed UDP Port:
2807		CONFIG_TFTP_PORT
2808
2809		If this is defined, the environment variable tftpsrcp
2810		is used to supply the TFTP UDP source port value.
2811		If tftpsrcp isn't defined, the normal pseudo-random port
2812		number generator is used.
2813
2814		Also, the environment variable tftpdstp is used to supply
2815		the TFTP UDP destination port value.  If tftpdstp isn't
2816		defined, the normal port 69 is used.
2817
2818		The purpose for tftpsrcp is to allow a TFTP server to
2819		blindly start the TFTP transfer using the pre-configured
2820		target IP address and UDP port. This has the effect of
2821		"punching through" the (Windows XP) firewall, allowing
2822		the remainder of the TFTP transfer to proceed normally.
2823		A better solution is to properly configure the firewall,
2824		but sometimes that is not allowed.
2825
2826- Hashing support:
2827		CONFIG_CMD_HASH
2828
2829		This enables a generic 'hash' command which can produce
2830		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
2831
2832		CONFIG_HASH_VERIFY
2833
2834		Enable the hash verify command (hash -v). This adds to code
2835		size a little.
2836
2837		CONFIG_SHA1 - support SHA1 hashing
2838		CONFIG_SHA256 - support SHA256 hashing
2839
2840		Note: There is also a sha1sum command, which should perhaps
2841		be deprecated in favour of 'hash sha1'.
2842
2843- Freescale i.MX specific commands:
2844		CONFIG_CMD_HDMIDETECT
2845		This enables 'hdmidet' command which returns true if an
2846		HDMI monitor is detected.  This command is i.MX 6 specific.
2847
2848		CONFIG_CMD_BMODE
2849		This enables the 'bmode' (bootmode) command for forcing
2850		a boot from specific media.
2851
2852		This is useful for forcing the ROM's usb downloader to
2853		activate upon a watchdog reset which is nice when iterating
2854		on U-Boot.  Using the reset button or running bmode normal
2855		will set it back to normal.  This command currently
2856		supports i.MX53 and i.MX6.
2857
2858- Signing support:
2859		CONFIG_RSA
2860
2861		This enables the RSA algorithm used for FIT image verification
2862		in U-Boot. See doc/uImage.FIT/signature.txt for more information.
2863
2864		The signing part is build into mkimage regardless of this
2865		option.
2866
2867- bootcount support:
2868		CONFIG_BOOTCOUNT_LIMIT
2869
2870		This enables the bootcounter support, see:
2871		http://www.denx.de/wiki/DULG/UBootBootCountLimit
2872
2873		CONFIG_AT91SAM9XE
2874		enable special bootcounter support on at91sam9xe based boards.
2875		CONFIG_BLACKFIN
2876		enable special bootcounter support on blackfin based boards.
2877		CONFIG_SOC_DA8XX
2878		enable special bootcounter support on da850 based boards.
2879		CONFIG_BOOTCOUNT_RAM
2880		enable support for the bootcounter in RAM
2881		CONFIG_BOOTCOUNT_I2C
2882		enable support for the bootcounter on an i2c (like RTC) device.
2883			CONFIG_SYS_I2C_RTC_ADDR = i2c chip address
2884			CONFIG_SYS_BOOTCOUNT_ADDR = i2c addr which is used for
2885						    the bootcounter.
2886			CONFIG_BOOTCOUNT_ALEN = address len
2887
2888- Show boot progress:
2889		CONFIG_SHOW_BOOT_PROGRESS
2890
2891		Defining this option allows to add some board-
2892		specific code (calling a user-provided function
2893		"show_boot_progress(int)") that enables you to show
2894		the system's boot progress on some display (for
2895		example, some LED's) on your board. At the moment,
2896		the following checkpoints are implemented:
2897
2898- Detailed boot stage timing
2899		CONFIG_BOOTSTAGE
2900		Define this option to get detailed timing of each stage
2901		of the boot process.
2902
2903		CONFIG_BOOTSTAGE_USER_COUNT
2904		This is the number of available user bootstage records.
2905		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
2906		a new ID will be allocated from this stash. If you exceed
2907		the limit, recording will stop.
2908
2909		CONFIG_BOOTSTAGE_REPORT
2910		Define this to print a report before boot, similar to this:
2911
2912		Timer summary in microseconds:
2913		       Mark    Elapsed  Stage
2914			  0          0  reset
2915		  3,575,678  3,575,678  board_init_f start
2916		  3,575,695         17  arch_cpu_init A9
2917		  3,575,777         82  arch_cpu_init done
2918		  3,659,598     83,821  board_init_r start
2919		  3,910,375    250,777  main_loop
2920		 29,916,167 26,005,792  bootm_start
2921		 30,361,327    445,160  start_kernel
2922
2923		CONFIG_CMD_BOOTSTAGE
2924		Add a 'bootstage' command which supports printing a report
2925		and un/stashing of bootstage data.
2926
2927		CONFIG_BOOTSTAGE_FDT
2928		Stash the bootstage information in the FDT. A root 'bootstage'
2929		node is created with each bootstage id as a child. Each child
2930		has a 'name' property and either 'mark' containing the
2931		mark time in microsecond, or 'accum' containing the
2932		accumulated time for that bootstage id in microseconds.
2933		For example:
2934
2935		bootstage {
2936			154 {
2937				name = "board_init_f";
2938				mark = <3575678>;
2939			};
2940			170 {
2941				name = "lcd";
2942				accum = <33482>;
2943			};
2944		};
2945
2946		Code in the Linux kernel can find this in /proc/devicetree.
2947
2948Legacy uImage format:
2949
2950  Arg	Where			When
2951    1	common/cmd_bootm.c	before attempting to boot an image
2952   -1	common/cmd_bootm.c	Image header has bad	 magic number
2953    2	common/cmd_bootm.c	Image header has correct magic number
2954   -2	common/cmd_bootm.c	Image header has bad	 checksum
2955    3	common/cmd_bootm.c	Image header has correct checksum
2956   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2957    4	common/cmd_bootm.c	Image data   has correct checksum
2958   -4	common/cmd_bootm.c	Image is for unsupported architecture
2959    5	common/cmd_bootm.c	Architecture check OK
2960   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2961    6	common/cmd_bootm.c	Image Type check OK
2962   -6	common/cmd_bootm.c	gunzip uncompression error
2963   -7	common/cmd_bootm.c	Unimplemented compression type
2964    7	common/cmd_bootm.c	Uncompression OK
2965    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2966   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2967
2968    9	common/image.c		Start initial ramdisk verification
2969  -10	common/image.c		Ramdisk header has bad	   magic number
2970  -11	common/image.c		Ramdisk header has bad	   checksum
2971   10	common/image.c		Ramdisk header is OK
2972  -12	common/image.c		Ramdisk data   has bad	   checksum
2973   11	common/image.c		Ramdisk data   has correct checksum
2974   12	common/image.c		Ramdisk verification complete, start loading
2975  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2976   13	common/image.c		Start multifile image verification
2977   14	common/image.c		No initial ramdisk, no multifile, continue.
2978
2979   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2980
2981  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2982  -31	post/post.c		POST test failed, detected by post_output_backlog()
2983  -32	post/post.c		POST test failed, detected by post_run_single()
2984
2985   34	common/cmd_doc.c	before loading a Image from a DOC device
2986  -35	common/cmd_doc.c	Bad usage of "doc" command
2987   35	common/cmd_doc.c	correct usage of "doc" command
2988  -36	common/cmd_doc.c	No boot device
2989   36	common/cmd_doc.c	correct boot device
2990  -37	common/cmd_doc.c	Unknown Chip ID on boot device
2991   37	common/cmd_doc.c	correct chip ID found, device available
2992  -38	common/cmd_doc.c	Read Error on boot device
2993   38	common/cmd_doc.c	reading Image header from DOC device OK
2994  -39	common/cmd_doc.c	Image header has bad magic number
2995   39	common/cmd_doc.c	Image header has correct magic number
2996  -40	common/cmd_doc.c	Error reading Image from DOC device
2997   40	common/cmd_doc.c	Image header has correct magic number
2998   41	common/cmd_ide.c	before loading a Image from a IDE device
2999  -42	common/cmd_ide.c	Bad usage of "ide" command
3000   42	common/cmd_ide.c	correct usage of "ide" command
3001  -43	common/cmd_ide.c	No boot device
3002   43	common/cmd_ide.c	boot device found
3003  -44	common/cmd_ide.c	Device not available
3004   44	common/cmd_ide.c	Device available
3005  -45	common/cmd_ide.c	wrong partition selected
3006   45	common/cmd_ide.c	partition selected
3007  -46	common/cmd_ide.c	Unknown partition table
3008   46	common/cmd_ide.c	valid partition table found
3009  -47	common/cmd_ide.c	Invalid partition type
3010   47	common/cmd_ide.c	correct partition type
3011  -48	common/cmd_ide.c	Error reading Image Header on boot device
3012   48	common/cmd_ide.c	reading Image Header from IDE device OK
3013  -49	common/cmd_ide.c	Image header has bad magic number
3014   49	common/cmd_ide.c	Image header has correct magic number
3015  -50	common/cmd_ide.c	Image header has bad	 checksum
3016   50	common/cmd_ide.c	Image header has correct checksum
3017  -51	common/cmd_ide.c	Error reading Image from IDE device
3018   51	common/cmd_ide.c	reading Image from IDE device OK
3019   52	common/cmd_nand.c	before loading a Image from a NAND device
3020  -53	common/cmd_nand.c	Bad usage of "nand" command
3021   53	common/cmd_nand.c	correct usage of "nand" command
3022  -54	common/cmd_nand.c	No boot device
3023   54	common/cmd_nand.c	boot device found
3024  -55	common/cmd_nand.c	Unknown Chip ID on boot device
3025   55	common/cmd_nand.c	correct chip ID found, device available
3026  -56	common/cmd_nand.c	Error reading Image Header on boot device
3027   56	common/cmd_nand.c	reading Image Header from NAND device OK
3028  -57	common/cmd_nand.c	Image header has bad magic number
3029   57	common/cmd_nand.c	Image header has correct magic number
3030  -58	common/cmd_nand.c	Error reading Image from NAND device
3031   58	common/cmd_nand.c	reading Image from NAND device OK
3032
3033  -60	common/env_common.c	Environment has a bad CRC, using default
3034
3035   64	net/eth.c		starting with Ethernet configuration.
3036  -64	net/eth.c		no Ethernet found.
3037   65	net/eth.c		Ethernet found.
3038
3039  -80	common/cmd_net.c	usage wrong
3040   80	common/cmd_net.c	before calling NetLoop()
3041  -81	common/cmd_net.c	some error in NetLoop() occurred
3042   81	common/cmd_net.c	NetLoop() back without error
3043  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
3044   82	common/cmd_net.c	trying automatic boot
3045   83	common/cmd_net.c	running "source" command
3046  -83	common/cmd_net.c	some error in automatic boot or "source" command
3047   84	common/cmd_net.c	end without errors
3048
3049FIT uImage format:
3050
3051  Arg	Where			When
3052  100	common/cmd_bootm.c	Kernel FIT Image has correct format
3053 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
3054  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
3055 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
3056  102	common/cmd_bootm.c	Kernel unit name specified
3057 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
3058  103	common/cmd_bootm.c	Found configuration node
3059  104	common/cmd_bootm.c	Got kernel subimage node offset
3060 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
3061  105	common/cmd_bootm.c	Kernel subimage hash verification OK
3062 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
3063  106	common/cmd_bootm.c	Architecture check OK
3064 -106	common/cmd_bootm.c	Kernel subimage has wrong type
3065  107	common/cmd_bootm.c	Kernel subimage type OK
3066 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
3067  108	common/cmd_bootm.c	Got kernel subimage data/size
3068 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
3069 -109	common/cmd_bootm.c	Can't get kernel subimage type
3070 -110	common/cmd_bootm.c	Can't get kernel subimage comp
3071 -111	common/cmd_bootm.c	Can't get kernel subimage os
3072 -112	common/cmd_bootm.c	Can't get kernel subimage load address
3073 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
3074
3075  120	common/image.c		Start initial ramdisk verification
3076 -120	common/image.c		Ramdisk FIT image has incorrect format
3077  121	common/image.c		Ramdisk FIT image has correct format
3078  122	common/image.c		No ramdisk subimage unit name, using configuration
3079 -122	common/image.c		Can't get configuration for ramdisk subimage
3080  123	common/image.c		Ramdisk unit name specified
3081 -124	common/image.c		Can't get ramdisk subimage node offset
3082  125	common/image.c		Got ramdisk subimage node offset
3083 -125	common/image.c		Ramdisk subimage hash verification failed
3084  126	common/image.c		Ramdisk subimage hash verification OK
3085 -126	common/image.c		Ramdisk subimage for unsupported architecture
3086  127	common/image.c		Architecture check OK
3087 -127	common/image.c		Can't get ramdisk subimage data/size
3088  128	common/image.c		Got ramdisk subimage data/size
3089  129	common/image.c		Can't get ramdisk load address
3090 -129	common/image.c		Got ramdisk load address
3091
3092 -130	common/cmd_doc.c	Incorrect FIT image format
3093  131	common/cmd_doc.c	FIT image format OK
3094
3095 -140	common/cmd_ide.c	Incorrect FIT image format
3096  141	common/cmd_ide.c	FIT image format OK
3097
3098 -150	common/cmd_nand.c	Incorrect FIT image format
3099  151	common/cmd_nand.c	FIT image format OK
3100
3101- FIT image support:
3102		CONFIG_FIT
3103		Enable support for the FIT uImage format.
3104
3105		CONFIG_FIT_BEST_MATCH
3106		When no configuration is explicitly selected, default to the
3107		one whose fdt's compatibility field best matches that of
3108		U-Boot itself. A match is considered "best" if it matches the
3109		most specific compatibility entry of U-Boot's fdt's root node.
3110		The order of entries in the configuration's fdt is ignored.
3111
3112		CONFIG_FIT_SIGNATURE
3113		This option enables signature verification of FIT uImages,
3114		using a hash signed and verified using RSA. See
3115		doc/uImage.FIT/signature.txt for more details.
3116
3117- Standalone program support:
3118		CONFIG_STANDALONE_LOAD_ADDR
3119
3120		This option defines a board specific value for the
3121		address where standalone program gets loaded, thus
3122		overwriting the architecture dependent default
3123		settings.
3124
3125- Frame Buffer Address:
3126		CONFIG_FB_ADDR
3127
3128		Define CONFIG_FB_ADDR if you want to use specific
3129		address for frame buffer.  This is typically the case
3130		when using a graphics controller has separate video
3131		memory.  U-Boot will then place the frame buffer at
3132		the given address instead of dynamically reserving it
3133		in system RAM by calling lcd_setmem(), which grabs
3134		the memory for the frame buffer depending on the
3135		configured panel size.
3136
3137		Please see board_init_f function.
3138
3139- Automatic software updates via TFTP server
3140		CONFIG_UPDATE_TFTP
3141		CONFIG_UPDATE_TFTP_CNT_MAX
3142		CONFIG_UPDATE_TFTP_MSEC_MAX
3143
3144		These options enable and control the auto-update feature;
3145		for a more detailed description refer to doc/README.update.
3146
3147- MTD Support (mtdparts command, UBI support)
3148		CONFIG_MTD_DEVICE
3149
3150		Adds the MTD device infrastructure from the Linux kernel.
3151		Needed for mtdparts command support.
3152
3153		CONFIG_MTD_PARTITIONS
3154
3155		Adds the MTD partitioning infrastructure from the Linux
3156		kernel. Needed for UBI support.
3157
3158- UBI support
3159		CONFIG_CMD_UBI
3160
3161		Adds commands for interacting with MTD partitions formatted
3162		with the UBI flash translation layer
3163
3164		Requires also defining CONFIG_RBTREE
3165
3166		CONFIG_UBI_SILENCE_MSG
3167
3168		Make the verbose messages from UBI stop printing.  This leaves
3169		warnings and errors enabled.
3170
3171- UBIFS support
3172		CONFIG_CMD_UBIFS
3173
3174		Adds commands for interacting with UBI volumes formatted as
3175		UBIFS.  UBIFS is read-only in u-boot.
3176
3177		Requires UBI support as well as CONFIG_LZO
3178
3179		CONFIG_UBIFS_SILENCE_MSG
3180
3181		Make the verbose messages from UBIFS stop printing.  This leaves
3182		warnings and errors enabled.
3183
3184- SPL framework
3185		CONFIG_SPL
3186		Enable building of SPL globally.
3187
3188		CONFIG_SPL_LDSCRIPT
3189		LDSCRIPT for linking the SPL binary.
3190
3191		CONFIG_SPL_MAX_FOOTPRINT
3192		Maximum size in memory allocated to the SPL, BSS included.
3193		When defined, the linker checks that the actual memory
3194		used by SPL from _start to __bss_end does not exceed it.
3195		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3196		must not be both defined at the same time.
3197
3198		CONFIG_SPL_MAX_SIZE
3199		Maximum size of the SPL image (text, data, rodata, and
3200		linker lists sections), BSS excluded.
3201		When defined, the linker checks that the actual size does
3202		not exceed it.
3203
3204		CONFIG_SPL_TEXT_BASE
3205		TEXT_BASE for linking the SPL binary.
3206
3207		CONFIG_SPL_RELOC_TEXT_BASE
3208		Address to relocate to.  If unspecified, this is equal to
3209		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3210
3211		CONFIG_SPL_BSS_START_ADDR
3212		Link address for the BSS within the SPL binary.
3213
3214		CONFIG_SPL_BSS_MAX_SIZE
3215		Maximum size in memory allocated to the SPL BSS.
3216		When defined, the linker checks that the actual memory used
3217		by SPL from __bss_start to __bss_end does not exceed it.
3218		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3219		must not be both defined at the same time.
3220
3221		CONFIG_SPL_STACK
3222		Adress of the start of the stack SPL will use
3223
3224		CONFIG_SPL_RELOC_STACK
3225		Adress of the start of the stack SPL will use after
3226		relocation.  If unspecified, this is equal to
3227		CONFIG_SPL_STACK.
3228
3229		CONFIG_SYS_SPL_MALLOC_START
3230		Starting address of the malloc pool used in SPL.
3231
3232		CONFIG_SYS_SPL_MALLOC_SIZE
3233		The size of the malloc pool used in SPL.
3234
3235		CONFIG_SPL_FRAMEWORK
3236		Enable the SPL framework under common/.  This framework
3237		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3238		NAND loading of the Linux Kernel.
3239
3240		CONFIG_SPL_DISPLAY_PRINT
3241		For ARM, enable an optional function to print more information
3242		about the running system.
3243
3244		CONFIG_SPL_INIT_MINIMAL
3245		Arch init code should be built for a very small image
3246
3247		CONFIG_SPL_LIBCOMMON_SUPPORT
3248		Support for common/libcommon.o in SPL binary
3249
3250		CONFIG_SPL_LIBDISK_SUPPORT
3251		Support for disk/libdisk.o in SPL binary
3252
3253		CONFIG_SPL_I2C_SUPPORT
3254		Support for drivers/i2c/libi2c.o in SPL binary
3255
3256		CONFIG_SPL_GPIO_SUPPORT
3257		Support for drivers/gpio/libgpio.o in SPL binary
3258
3259		CONFIG_SPL_MMC_SUPPORT
3260		Support for drivers/mmc/libmmc.o in SPL binary
3261
3262		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3263		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3264		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
3265		Address, size and partition on the MMC to load U-Boot from
3266		when the MMC is being used in raw mode.
3267
3268		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3269		Sector to load kernel uImage from when MMC is being
3270		used in raw mode (for Falcon mode)
3271
3272		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3273		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3274		Sector and number of sectors to load kernel argument
3275		parameters from when MMC is being used in raw mode
3276		(for falcon mode)
3277
3278		CONFIG_SPL_FAT_SUPPORT
3279		Support for fs/fat/libfat.o in SPL binary
3280
3281		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
3282		Filename to read to load U-Boot when reading from FAT
3283
3284		CONFIG_SPL_FAT_LOAD_KERNEL_NAME
3285		Filename to read to load kernel uImage when reading
3286		from FAT (for Falcon mode)
3287
3288		CONFIG_SPL_FAT_LOAD_ARGS_NAME
3289		Filename to read to load kernel argument parameters
3290		when reading from FAT (for Falcon mode)
3291
3292		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3293		Set this for NAND SPL on PPC mpc83xx targets, so that
3294		start.S waits for the rest of the SPL to load before
3295		continuing (the hardware starts execution after just
3296		loading the first page rather than the full 4K).
3297
3298		CONFIG_SPL_NAND_BASE
3299		Include nand_base.c in the SPL.  Requires
3300		CONFIG_SPL_NAND_DRIVERS.
3301
3302		CONFIG_SPL_NAND_DRIVERS
3303		SPL uses normal NAND drivers, not minimal drivers.
3304
3305		CONFIG_SPL_NAND_ECC
3306		Include standard software ECC in the SPL
3307
3308		CONFIG_SPL_NAND_SIMPLE
3309		Support for NAND boot using simple NAND drivers that
3310		expose the cmd_ctrl() interface.
3311
3312		CONFIG_SPL_MPC8XXX_INIT_DDR_SUPPORT
3313		Set for the SPL on PPC mpc8xxx targets, support for
3314		drivers/ddr/fsl/libddr.o in SPL binary.
3315
3316		CONFIG_SPL_COMMON_INIT_DDR
3317		Set for common ddr init with serial presence detect in
3318		SPL binary.
3319
3320		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3321		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3322		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3323		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3324		CONFIG_SYS_NAND_ECCBYTES
3325		Defines the size and behavior of the NAND that SPL uses
3326		to read U-Boot
3327
3328		CONFIG_SPL_NAND_BOOT
3329		Add support NAND boot
3330
3331		CONFIG_SYS_NAND_U_BOOT_OFFS
3332		Location in NAND to read U-Boot from
3333
3334		CONFIG_SYS_NAND_U_BOOT_DST
3335		Location in memory to load U-Boot to
3336
3337		CONFIG_SYS_NAND_U_BOOT_SIZE
3338		Size of image to load
3339
3340		CONFIG_SYS_NAND_U_BOOT_START
3341		Entry point in loaded image to jump to
3342
3343		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3344		Define this if you need to first read the OOB and then the
3345		data. This is used for example on davinci plattforms.
3346
3347		CONFIG_SPL_OMAP3_ID_NAND
3348		Support for an OMAP3-specific set of functions to return the
3349		ID and MFR of the first attached NAND chip, if present.
3350
3351		CONFIG_SPL_SERIAL_SUPPORT
3352		Support for drivers/serial/libserial.o in SPL binary
3353
3354		CONFIG_SPL_SPI_FLASH_SUPPORT
3355		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
3356
3357		CONFIG_SPL_SPI_SUPPORT
3358		Support for drivers/spi/libspi.o in SPL binary
3359
3360		CONFIG_SPL_RAM_DEVICE
3361		Support for running image already present in ram, in SPL binary
3362
3363		CONFIG_SPL_LIBGENERIC_SUPPORT
3364		Support for lib/libgeneric.o in SPL binary
3365
3366		CONFIG_SPL_ENV_SUPPORT
3367		Support for the environment operating in SPL binary
3368
3369		CONFIG_SPL_NET_SUPPORT
3370		Support for the net/libnet.o in SPL binary.
3371		It conflicts with SPL env from storage medium specified by
3372		CONFIG_ENV_IS_xxx but CONFIG_ENV_IS_NOWHERE
3373
3374		CONFIG_SPL_PAD_TO
3375		Image offset to which the SPL should be padded before appending
3376		the SPL payload. By default, this is defined as
3377		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3378		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3379		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3380
3381		CONFIG_SPL_TARGET
3382		Final target image containing SPL and payload.  Some SPLs
3383		use an arch-specific makefile fragment instead, for
3384		example if more than one image needs to be produced.
3385
3386		CONFIG_FIT_SPL_PRINT
3387		Printing information about a FIT image adds quite a bit of
3388		code to SPL. So this is normally disabled in SPL. Use this
3389		option to re-enable it. This will affect the output of the
3390		bootm command when booting a FIT image.
3391
3392- TPL framework
3393		CONFIG_TPL
3394		Enable building of TPL globally.
3395
3396		CONFIG_TPL_PAD_TO
3397		Image offset to which the TPL should be padded before appending
3398		the TPL payload. By default, this is defined as
3399		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3400		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3401		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3402
3403Modem Support:
3404--------------
3405
3406[so far only for SMDK2400 boards]
3407
3408- Modem support enable:
3409		CONFIG_MODEM_SUPPORT
3410
3411- RTS/CTS Flow control enable:
3412		CONFIG_HWFLOW
3413
3414- Modem debug support:
3415		CONFIG_MODEM_SUPPORT_DEBUG
3416
3417		Enables debugging stuff (char screen[1024], dbg())
3418		for modem support. Useful only with BDI2000.
3419
3420- Interrupt support (PPC):
3421
3422		There are common interrupt_init() and timer_interrupt()
3423		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3424		for CPU specific initialization. interrupt_init_cpu()
3425		should set decrementer_count to appropriate value. If
3426		CPU resets decrementer automatically after interrupt
3427		(ppc4xx) it should set decrementer_count to zero.
3428		timer_interrupt() calls timer_interrupt_cpu() for CPU
3429		specific handling. If board has watchdog / status_led
3430		/ other_activity_monitor it works automatically from
3431		general timer_interrupt().
3432
3433- General:
3434
3435		In the target system modem support is enabled when a
3436		specific key (key combination) is pressed during
3437		power-on. Otherwise U-Boot will boot normally
3438		(autoboot). The key_pressed() function is called from
3439		board_init(). Currently key_pressed() is a dummy
3440		function, returning 1 and thus enabling modem
3441		initialization.
3442
3443		If there are no modem init strings in the
3444		environment, U-Boot proceed to autoboot; the
3445		previous output (banner, info printfs) will be
3446		suppressed, though.
3447
3448		See also: doc/README.Modem
3449
3450Board initialization settings:
3451------------------------------
3452
3453During Initialization u-boot calls a number of board specific functions
3454to allow the preparation of board specific prerequisites, e.g. pin setup
3455before drivers are initialized. To enable these callbacks the
3456following configuration macros have to be defined. Currently this is
3457architecture specific, so please check arch/your_architecture/lib/board.c
3458typically in board_init_f() and board_init_r().
3459
3460- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3461- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3462- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3463- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3464
3465Configuration Settings:
3466-----------------------
3467
3468- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3469		undefine this when you're short of memory.
3470
3471- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3472		width of the commands listed in the 'help' command output.
3473
3474- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3475		prompt for user input.
3476
3477- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3478
3479- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3480
3481- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3482
3483- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3484		the application (usually a Linux kernel) when it is
3485		booted
3486
3487- CONFIG_SYS_BAUDRATE_TABLE:
3488		List of legal baudrate settings for this board.
3489
3490- CONFIG_SYS_CONSOLE_INFO_QUIET
3491		Suppress display of console information at boot.
3492
3493- CONFIG_SYS_CONSOLE_IS_IN_ENV
3494		If the board specific function
3495			extern int overwrite_console (void);
3496		returns 1, the stdin, stderr and stdout are switched to the
3497		serial port, else the settings in the environment are used.
3498
3499- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3500		Enable the call to overwrite_console().
3501
3502- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3503		Enable overwrite of previous console environment settings.
3504
3505- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3506		Begin and End addresses of the area used by the
3507		simple memory test.
3508
3509- CONFIG_SYS_ALT_MEMTEST:
3510		Enable an alternate, more extensive memory test.
3511
3512- CONFIG_SYS_MEMTEST_SCRATCH:
3513		Scratch address used by the alternate memory test
3514		You only need to set this if address zero isn't writeable
3515
3516- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
3517		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3518		this specified memory area will get subtracted from the top
3519		(end) of RAM and won't get "touched" at all by U-Boot. By
3520		fixing up gd->ram_size the Linux kernel should gets passed
3521		the now "corrected" memory size and won't touch it either.
3522		This should work for arch/ppc and arch/powerpc. Only Linux
3523		board ports in arch/powerpc with bootwrapper support that
3524		recalculate the memory size from the SDRAM controller setup
3525		will have to get fixed in Linux additionally.
3526
3527		This option can be used as a workaround for the 440EPx/GRx
3528		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3529		be touched.
3530
3531		WARNING: Please make sure that this value is a multiple of
3532		the Linux page size (normally 4k). If this is not the case,
3533		then the end address of the Linux memory will be located at a
3534		non page size aligned address and this could cause major
3535		problems.
3536
3537- CONFIG_SYS_LOADS_BAUD_CHANGE:
3538		Enable temporary baudrate change while serial download
3539
3540- CONFIG_SYS_SDRAM_BASE:
3541		Physical start address of SDRAM. _Must_ be 0 here.
3542
3543- CONFIG_SYS_MBIO_BASE:
3544		Physical start address of Motherboard I/O (if using a
3545		Cogent motherboard)
3546
3547- CONFIG_SYS_FLASH_BASE:
3548		Physical start address of Flash memory.
3549
3550- CONFIG_SYS_MONITOR_BASE:
3551		Physical start address of boot monitor code (set by
3552		make config files to be same as the text base address
3553		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3554		CONFIG_SYS_FLASH_BASE when booting from flash.
3555
3556- CONFIG_SYS_MONITOR_LEN:
3557		Size of memory reserved for monitor code, used to
3558		determine _at_compile_time_ (!) if the environment is
3559		embedded within the U-Boot image, or in a separate
3560		flash sector.
3561
3562- CONFIG_SYS_MALLOC_LEN:
3563		Size of DRAM reserved for malloc() use.
3564
3565- CONFIG_SYS_BOOTM_LEN:
3566		Normally compressed uImages are limited to an
3567		uncompressed size of 8 MBytes. If this is not enough,
3568		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3569		to adjust this setting to your needs.
3570
3571- CONFIG_SYS_BOOTMAPSZ:
3572		Maximum size of memory mapped by the startup code of
3573		the Linux kernel; all data that must be processed by
3574		the Linux kernel (bd_info, boot arguments, FDT blob if
3575		used) must be put below this limit, unless "bootm_low"
3576		environment variable is defined and non-zero. In such case
3577		all data for the Linux kernel must be between "bootm_low"
3578		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3579		variable "bootm_mapsize" will override the value of
3580		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3581		then the value in "bootm_size" will be used instead.
3582
3583- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3584		Enable initrd_high functionality.  If defined then the
3585		initrd_high feature is enabled and the bootm ramdisk subcommand
3586		is enabled.
3587
3588- CONFIG_SYS_BOOT_GET_CMDLINE:
3589		Enables allocating and saving kernel cmdline in space between
3590		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3591
3592- CONFIG_SYS_BOOT_GET_KBD:
3593		Enables allocating and saving a kernel copy of the bd_info in
3594		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3595
3596- CONFIG_SYS_MAX_FLASH_BANKS:
3597		Max number of Flash memory banks
3598
3599- CONFIG_SYS_MAX_FLASH_SECT:
3600		Max number of sectors on a Flash chip
3601
3602- CONFIG_SYS_FLASH_ERASE_TOUT:
3603		Timeout for Flash erase operations (in ms)
3604
3605- CONFIG_SYS_FLASH_WRITE_TOUT:
3606		Timeout for Flash write operations (in ms)
3607
3608- CONFIG_SYS_FLASH_LOCK_TOUT
3609		Timeout for Flash set sector lock bit operation (in ms)
3610
3611- CONFIG_SYS_FLASH_UNLOCK_TOUT
3612		Timeout for Flash clear lock bits operation (in ms)
3613
3614- CONFIG_SYS_FLASH_PROTECTION
3615		If defined, hardware flash sectors protection is used
3616		instead of U-Boot software protection.
3617
3618- CONFIG_SYS_DIRECT_FLASH_TFTP:
3619
3620		Enable TFTP transfers directly to flash memory;
3621		without this option such a download has to be
3622		performed in two steps: (1) download to RAM, and (2)
3623		copy from RAM to flash.
3624
3625		The two-step approach is usually more reliable, since
3626		you can check if the download worked before you erase
3627		the flash, but in some situations (when system RAM is
3628		too limited to allow for a temporary copy of the
3629		downloaded image) this option may be very useful.
3630
3631- CONFIG_SYS_FLASH_CFI:
3632		Define if the flash driver uses extra elements in the
3633		common flash structure for storing flash geometry.
3634
3635- CONFIG_FLASH_CFI_DRIVER
3636		This option also enables the building of the cfi_flash driver
3637		in the drivers directory
3638
3639- CONFIG_FLASH_CFI_MTD
3640		This option enables the building of the cfi_mtd driver
3641		in the drivers directory. The driver exports CFI flash
3642		to the MTD layer.
3643
3644- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3645		Use buffered writes to flash.
3646
3647- CONFIG_FLASH_SPANSION_S29WS_N
3648		s29ws-n MirrorBit flash has non-standard addresses for buffered
3649		write commands.
3650
3651- CONFIG_SYS_FLASH_QUIET_TEST
3652		If this option is defined, the common CFI flash doesn't
3653		print it's warning upon not recognized FLASH banks. This
3654		is useful, if some of the configured banks are only
3655		optionally available.
3656
3657- CONFIG_FLASH_SHOW_PROGRESS
3658		If defined (must be an integer), print out countdown
3659		digits and dots.  Recommended value: 45 (9..1) for 80
3660		column displays, 15 (3..1) for 40 column displays.
3661
3662- CONFIG_FLASH_VERIFY
3663		If defined, the content of the flash (destination) is compared
3664		against the source after the write operation. An error message
3665		will be printed when the contents are not identical.
3666		Please note that this option is useless in nearly all cases,
3667		since such flash programming errors usually are detected earlier
3668		while unprotecting/erasing/programming. Please only enable
3669		this option if you really know what you are doing.
3670
3671- CONFIG_SYS_RX_ETH_BUFFER:
3672		Defines the number of Ethernet receive buffers. On some
3673		Ethernet controllers it is recommended to set this value
3674		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3675		buffers can be full shortly after enabling the interface
3676		on high Ethernet traffic.
3677		Defaults to 4 if not defined.
3678
3679- CONFIG_ENV_MAX_ENTRIES
3680
3681	Maximum number of entries in the hash table that is used
3682	internally to store the environment settings. The default
3683	setting is supposed to be generous and should work in most
3684	cases. This setting can be used to tune behaviour; see
3685	lib/hashtable.c for details.
3686
3687- CONFIG_ENV_FLAGS_LIST_DEFAULT
3688- CONFIG_ENV_FLAGS_LIST_STATIC
3689	Enable validation of the values given to environment variables when
3690	calling env set.  Variables can be restricted to only decimal,
3691	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3692	the variables can also be restricted to IP address or MAC address.
3693
3694	The format of the list is:
3695		type_attribute = [s|d|x|b|i|m]
3696		access_atribute = [a|r|o|c]
3697		attributes = type_attribute[access_atribute]
3698		entry = variable_name[:attributes]
3699		list = entry[,list]
3700
3701	The type attributes are:
3702		s - String (default)
3703		d - Decimal
3704		x - Hexadecimal
3705		b - Boolean ([1yYtT|0nNfF])
3706		i - IP address
3707		m - MAC address
3708
3709	The access attributes are:
3710		a - Any (default)
3711		r - Read-only
3712		o - Write-once
3713		c - Change-default
3714
3715	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3716		Define this to a list (string) to define the ".flags"
3717		envirnoment variable in the default or embedded environment.
3718
3719	- CONFIG_ENV_FLAGS_LIST_STATIC
3720		Define this to a list (string) to define validation that
3721		should be done if an entry is not found in the ".flags"
3722		environment variable.  To override a setting in the static
3723		list, simply add an entry for the same variable name to the
3724		".flags" variable.
3725
3726- CONFIG_ENV_ACCESS_IGNORE_FORCE
3727	If defined, don't allow the -f switch to env set override variable
3728	access flags.
3729
3730- CONFIG_SYS_GENERIC_BOARD
3731	This selects the architecture-generic board system instead of the
3732	architecture-specific board files. It is intended to move boards
3733	to this new framework over time. Defining this will disable the
3734	arch/foo/lib/board.c file and use common/board_f.c and
3735	common/board_r.c instead. To use this option your architecture
3736	must support it (i.e. must define __HAVE_ARCH_GENERIC_BOARD in
3737	its config.mk file). If you find problems enabling this option on
3738	your board please report the problem and send patches!
3739
3740- CONFIG_SYS_SYM_OFFSETS
3741	This is set by architectures that use offsets for link symbols
3742	instead of absolute values. So bss_start is obtained using an
3743	offset _bss_start_ofs from CONFIG_SYS_TEXT_BASE, rather than
3744	directly. You should not need to touch this setting.
3745
3746- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
3747	This is set by OMAP boards for the max time that reset should
3748	be asserted. See doc/README.omap-reset-time for details on how
3749	the value can be calulated on a given board.
3750
3751The following definitions that deal with the placement and management
3752of environment data (variable area); in general, we support the
3753following configurations:
3754
3755- CONFIG_BUILD_ENVCRC:
3756
3757	Builds up envcrc with the target environment so that external utils
3758	may easily extract it and embed it in final U-Boot images.
3759
3760- CONFIG_ENV_IS_IN_FLASH:
3761
3762	Define this if the environment is in flash memory.
3763
3764	a) The environment occupies one whole flash sector, which is
3765	   "embedded" in the text segment with the U-Boot code. This
3766	   happens usually with "bottom boot sector" or "top boot
3767	   sector" type flash chips, which have several smaller
3768	   sectors at the start or the end. For instance, such a
3769	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3770	   such a case you would place the environment in one of the
3771	   4 kB sectors - with U-Boot code before and after it. With
3772	   "top boot sector" type flash chips, you would put the
3773	   environment in one of the last sectors, leaving a gap
3774	   between U-Boot and the environment.
3775
3776	- CONFIG_ENV_OFFSET:
3777
3778	   Offset of environment data (variable area) to the
3779	   beginning of flash memory; for instance, with bottom boot
3780	   type flash chips the second sector can be used: the offset
3781	   for this sector is given here.
3782
3783	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3784
3785	- CONFIG_ENV_ADDR:
3786
3787	   This is just another way to specify the start address of
3788	   the flash sector containing the environment (instead of
3789	   CONFIG_ENV_OFFSET).
3790
3791	- CONFIG_ENV_SECT_SIZE:
3792
3793	   Size of the sector containing the environment.
3794
3795
3796	b) Sometimes flash chips have few, equal sized, BIG sectors.
3797	   In such a case you don't want to spend a whole sector for
3798	   the environment.
3799
3800	- CONFIG_ENV_SIZE:
3801
3802	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3803	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3804	   of this flash sector for the environment. This saves
3805	   memory for the RAM copy of the environment.
3806
3807	   It may also save flash memory if you decide to use this
3808	   when your environment is "embedded" within U-Boot code,
3809	   since then the remainder of the flash sector could be used
3810	   for U-Boot code. It should be pointed out that this is
3811	   STRONGLY DISCOURAGED from a robustness point of view:
3812	   updating the environment in flash makes it always
3813	   necessary to erase the WHOLE sector. If something goes
3814	   wrong before the contents has been restored from a copy in
3815	   RAM, your target system will be dead.
3816
3817	- CONFIG_ENV_ADDR_REDUND
3818	  CONFIG_ENV_SIZE_REDUND
3819
3820	   These settings describe a second storage area used to hold
3821	   a redundant copy of the environment data, so that there is
3822	   a valid backup copy in case there is a power failure during
3823	   a "saveenv" operation.
3824
3825BE CAREFUL! Any changes to the flash layout, and some changes to the
3826source code will make it necessary to adapt <board>/u-boot.lds*
3827accordingly!
3828
3829
3830- CONFIG_ENV_IS_IN_NVRAM:
3831
3832	Define this if you have some non-volatile memory device
3833	(NVRAM, battery buffered SRAM) which you want to use for the
3834	environment.
3835
3836	- CONFIG_ENV_ADDR:
3837	- CONFIG_ENV_SIZE:
3838
3839	  These two #defines are used to determine the memory area you
3840	  want to use for environment. It is assumed that this memory
3841	  can just be read and written to, without any special
3842	  provision.
3843
3844BE CAREFUL! The first access to the environment happens quite early
3845in U-Boot initalization (when we try to get the setting of for the
3846console baudrate). You *MUST* have mapped your NVRAM area then, or
3847U-Boot will hang.
3848
3849Please note that even with NVRAM we still use a copy of the
3850environment in RAM: we could work on NVRAM directly, but we want to
3851keep settings there always unmodified except somebody uses "saveenv"
3852to save the current settings.
3853
3854
3855- CONFIG_ENV_IS_IN_EEPROM:
3856
3857	Use this if you have an EEPROM or similar serial access
3858	device and a driver for it.
3859
3860	- CONFIG_ENV_OFFSET:
3861	- CONFIG_ENV_SIZE:
3862
3863	  These two #defines specify the offset and size of the
3864	  environment area within the total memory of your EEPROM.
3865
3866	- CONFIG_SYS_I2C_EEPROM_ADDR:
3867	  If defined, specified the chip address of the EEPROM device.
3868	  The default address is zero.
3869
3870	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3871	  If defined, the number of bits used to address bytes in a
3872	  single page in the EEPROM device.  A 64 byte page, for example
3873	  would require six bits.
3874
3875	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3876	  If defined, the number of milliseconds to delay between
3877	  page writes.	The default is zero milliseconds.
3878
3879	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3880	  The length in bytes of the EEPROM memory array address.  Note
3881	  that this is NOT the chip address length!
3882
3883	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3884	  EEPROM chips that implement "address overflow" are ones
3885	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3886	  address and the extra bits end up in the "chip address" bit
3887	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3888	  byte chips.
3889
3890	  Note that we consider the length of the address field to
3891	  still be one byte because the extra address bits are hidden
3892	  in the chip address.
3893
3894	- CONFIG_SYS_EEPROM_SIZE:
3895	  The size in bytes of the EEPROM device.
3896
3897	- CONFIG_ENV_EEPROM_IS_ON_I2C
3898	  define this, if you have I2C and SPI activated, and your
3899	  EEPROM, which holds the environment, is on the I2C bus.
3900
3901	- CONFIG_I2C_ENV_EEPROM_BUS
3902	  if you have an Environment on an EEPROM reached over
3903	  I2C muxes, you can define here, how to reach this
3904	  EEPROM. For example:
3905
3906	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
3907
3908	  EEPROM which holds the environment, is reached over
3909	  a pca9547 i2c mux with address 0x70, channel 3.
3910
3911- CONFIG_ENV_IS_IN_DATAFLASH:
3912
3913	Define this if you have a DataFlash memory device which you
3914	want to use for the environment.
3915
3916	- CONFIG_ENV_OFFSET:
3917	- CONFIG_ENV_ADDR:
3918	- CONFIG_ENV_SIZE:
3919
3920	  These three #defines specify the offset and size of the
3921	  environment area within the total memory of your DataFlash placed
3922	  at the specified address.
3923
3924- CONFIG_ENV_IS_IN_REMOTE:
3925
3926	Define this if you have a remote memory space which you
3927	want to use for the local device's environment.
3928
3929	- CONFIG_ENV_ADDR:
3930	- CONFIG_ENV_SIZE:
3931
3932	  These two #defines specify the address and size of the
3933	  environment area within the remote memory space. The
3934	  local device can get the environment from remote memory
3935	  space by SRIO or PCIE links.
3936
3937BE CAREFUL! For some special cases, the local device can not use
3938"saveenv" command. For example, the local device will get the
3939environment stored in a remote NOR flash by SRIO or PCIE link,
3940but it can not erase, write this NOR flash by SRIO or PCIE interface.
3941
3942- CONFIG_ENV_IS_IN_NAND:
3943
3944	Define this if you have a NAND device which you want to use
3945	for the environment.
3946
3947	- CONFIG_ENV_OFFSET:
3948	- CONFIG_ENV_SIZE:
3949
3950	  These two #defines specify the offset and size of the environment
3951	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
3952	  aligned to an erase block boundary.
3953
3954	- CONFIG_ENV_OFFSET_REDUND (optional):
3955
3956	  This setting describes a second storage area of CONFIG_ENV_SIZE
3957	  size used to hold a redundant copy of the environment data, so
3958	  that there is a valid backup copy in case there is a power failure
3959	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
3960	  aligned to an erase block boundary.
3961
3962	- CONFIG_ENV_RANGE (optional):
3963
3964	  Specifies the length of the region in which the environment
3965	  can be written.  This should be a multiple of the NAND device's
3966	  block size.  Specifying a range with more erase blocks than
3967	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
3968	  the range to be avoided.
3969
3970	- CONFIG_ENV_OFFSET_OOB (optional):
3971
3972	  Enables support for dynamically retrieving the offset of the
3973	  environment from block zero's out-of-band data.  The
3974	  "nand env.oob" command can be used to record this offset.
3975	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
3976	  using CONFIG_ENV_OFFSET_OOB.
3977
3978- CONFIG_NAND_ENV_DST
3979
3980	Defines address in RAM to which the nand_spl code should copy the
3981	environment. If redundant environment is used, it will be copied to
3982	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3983
3984- CONFIG_ENV_IS_IN_UBI:
3985
3986	Define this if you have an UBI volume that you want to use for the
3987	environment.  This has the benefit of wear-leveling the environment
3988	accesses, which is important on NAND.
3989
3990	- CONFIG_ENV_UBI_PART:
3991
3992	  Define this to a string that is the mtd partition containing the UBI.
3993
3994	- CONFIG_ENV_UBI_VOLUME:
3995
3996	  Define this to the name of the volume that you want to store the
3997	  environment in.
3998
3999	- CONFIG_ENV_UBI_VOLUME_REDUND:
4000
4001	  Define this to the name of another volume to store a second copy of
4002	  the environment in.  This will enable redundant environments in UBI.
4003	  It is assumed that both volumes are in the same MTD partition.
4004
4005	- CONFIG_UBI_SILENCE_MSG
4006	- CONFIG_UBIFS_SILENCE_MSG
4007
4008	  You will probably want to define these to avoid a really noisy system
4009	  when storing the env in UBI.
4010
4011- CONFIG_ENV_IS_IN_MMC:
4012
4013	Define this if you have an MMC device which you want to use for the
4014	environment.
4015
4016	- CONFIG_SYS_MMC_ENV_DEV:
4017
4018	  Specifies which MMC device the environment is stored in.
4019
4020	- CONFIG_SYS_MMC_ENV_PART (optional):
4021
4022	  Specifies which MMC partition the environment is stored in. If not
4023	  set, defaults to partition 0, the user area. Common values might be
4024	  1 (first MMC boot partition), 2 (second MMC boot partition).
4025
4026	- CONFIG_ENV_OFFSET:
4027	- CONFIG_ENV_SIZE:
4028
4029	  These two #defines specify the offset and size of the environment
4030	  area within the specified MMC device.
4031
4032	  If offset is positive (the usual case), it is treated as relative to
4033	  the start of the MMC partition. If offset is negative, it is treated
4034	  as relative to the end of the MMC partition. This can be useful if
4035	  your board may be fitted with different MMC devices, which have
4036	  different sizes for the MMC partitions, and you always want the
4037	  environment placed at the very end of the partition, to leave the
4038	  maximum possible space before it, to store other data.
4039
4040	  These two values are in units of bytes, but must be aligned to an
4041	  MMC sector boundary.
4042
4043	- CONFIG_ENV_OFFSET_REDUND (optional):
4044
4045	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
4046	  hold a redundant copy of the environment data. This provides a
4047	  valid backup copy in case the other copy is corrupted, e.g. due
4048	  to a power failure during a "saveenv" operation.
4049
4050	  This value may also be positive or negative; this is handled in the
4051	  same way as CONFIG_ENV_OFFSET.
4052
4053	  This value is also in units of bytes, but must also be aligned to
4054	  an MMC sector boundary.
4055
4056	- CONFIG_ENV_SIZE_REDUND (optional):
4057
4058	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
4059	  set. If this value is set, it must be set to the same value as
4060	  CONFIG_ENV_SIZE.
4061
4062- CONFIG_SYS_SPI_INIT_OFFSET
4063
4064	Defines offset to the initial SPI buffer area in DPRAM. The
4065	area is used at an early stage (ROM part) if the environment
4066	is configured to reside in the SPI EEPROM: We need a 520 byte
4067	scratch DPRAM area. It is used between the two initialization
4068	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
4069	to be a good choice since it makes it far enough from the
4070	start of the data area as well as from the stack pointer.
4071
4072Please note that the environment is read-only until the monitor
4073has been relocated to RAM and a RAM copy of the environment has been
4074created; also, when using EEPROM you will have to use getenv_f()
4075until then to read environment variables.
4076
4077The environment is protected by a CRC32 checksum. Before the monitor
4078is relocated into RAM, as a result of a bad CRC you will be working
4079with the compiled-in default environment - *silently*!!! [This is
4080necessary, because the first environment variable we need is the
4081"baudrate" setting for the console - if we have a bad CRC, we don't
4082have any device yet where we could complain.]
4083
4084Note: once the monitor has been relocated, then it will complain if
4085the default environment is used; a new CRC is computed as soon as you
4086use the "saveenv" command to store a valid environment.
4087
4088- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
4089		Echo the inverted Ethernet link state to the fault LED.
4090
4091		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
4092		      also needs to be defined.
4093
4094- CONFIG_SYS_FAULT_MII_ADDR:
4095		MII address of the PHY to check for the Ethernet link state.
4096
4097- CONFIG_NS16550_MIN_FUNCTIONS:
4098		Define this if you desire to only have use of the NS16550_init
4099		and NS16550_putc functions for the serial driver located at
4100		drivers/serial/ns16550.c.  This option is useful for saving
4101		space for already greatly restricted images, including but not
4102		limited to NAND_SPL configurations.
4103
4104- CONFIG_DISPLAY_BOARDINFO
4105		Display information about the board that U-Boot is running on
4106		when U-Boot starts up. The board function checkboard() is called
4107		to do this.
4108
4109- CONFIG_DISPLAY_BOARDINFO_LATE
4110		Similar to the previous option, but display this information
4111		later, once stdio is running and output goes to the LCD, if
4112		present.
4113
4114Low Level (hardware related) configuration options:
4115---------------------------------------------------
4116
4117- CONFIG_SYS_CACHELINE_SIZE:
4118		Cache Line Size of the CPU.
4119
4120- CONFIG_SYS_DEFAULT_IMMR:
4121		Default address of the IMMR after system reset.
4122
4123		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4124		and RPXsuper) to be able to adjust the position of
4125		the IMMR register after a reset.
4126
4127- CONFIG_SYS_CCSRBAR_DEFAULT:
4128		Default (power-on reset) physical address of CCSR on Freescale
4129		PowerPC SOCs.
4130
4131- CONFIG_SYS_CCSRBAR:
4132		Virtual address of CCSR.  On a 32-bit build, this is typically
4133		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4134
4135		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4136		for cross-platform code that uses that macro instead.
4137
4138- CONFIG_SYS_CCSRBAR_PHYS:
4139		Physical address of CCSR.  CCSR can be relocated to a new
4140		physical address, if desired.  In this case, this macro should
4141		be set to that address.	 Otherwise, it should be set to the
4142		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
4143		is typically relocated on 36-bit builds.  It is recommended
4144		that this macro be defined via the _HIGH and _LOW macros:
4145
4146		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4147			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4148
4149- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4150		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
4151		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
4152		used in assembly code, so it must not contain typecasts or
4153		integer size suffixes (e.g. "ULL").
4154
4155- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4156		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
4157		used in assembly code, so it must not contain typecasts or
4158		integer size suffixes (e.g. "ULL").
4159
4160- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
4161		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4162		forced to a value that ensures that CCSR is not relocated.
4163
4164- Floppy Disk Support:
4165		CONFIG_SYS_FDC_DRIVE_NUMBER
4166
4167		the default drive number (default value 0)
4168
4169		CONFIG_SYS_ISA_IO_STRIDE
4170
4171		defines the spacing between FDC chipset registers
4172		(default value 1)
4173
4174		CONFIG_SYS_ISA_IO_OFFSET
4175
4176		defines the offset of register from address. It
4177		depends on which part of the data bus is connected to
4178		the FDC chipset. (default value 0)
4179
4180		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4181		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4182		default value.
4183
4184		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4185		fdc_hw_init() is called at the beginning of the FDC
4186		setup. fdc_hw_init() must be provided by the board
4187		source code. It is used to make hardware dependant
4188		initializations.
4189
4190- CONFIG_IDE_AHB:
4191		Most IDE controllers were designed to be connected with PCI
4192		interface. Only few of them were designed for AHB interface.
4193		When software is doing ATA command and data transfer to
4194		IDE devices through IDE-AHB controller, some additional
4195		registers accessing to these kind of IDE-AHB controller
4196		is requierd.
4197
4198- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4199		DO NOT CHANGE unless you know exactly what you're
4200		doing! (11-4) [MPC8xx/82xx systems only]
4201
4202- CONFIG_SYS_INIT_RAM_ADDR:
4203
4204		Start address of memory area that can be used for
4205		initial data and stack; please note that this must be
4206		writable memory that is working WITHOUT special
4207		initialization, i. e. you CANNOT use normal RAM which
4208		will become available only after programming the
4209		memory controller and running certain initialization
4210		sequences.
4211
4212		U-Boot uses the following memory types:
4213		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4214		- MPC824X: data cache
4215		- PPC4xx:  data cache
4216
4217- CONFIG_SYS_GBL_DATA_OFFSET:
4218
4219		Offset of the initial data structure in the memory
4220		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4221		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4222		data is located at the end of the available space
4223		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4224		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
4225		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4226		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4227
4228	Note:
4229		On the MPC824X (or other systems that use the data
4230		cache for initial memory) the address chosen for
4231		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4232		point to an otherwise UNUSED address space between
4233		the top of RAM and the start of the PCI space.
4234
4235- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4236
4237- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4238
4239- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4240
4241- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4242
4243- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4244
4245- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4246
4247- CONFIG_SYS_OR_TIMING_SDRAM:
4248		SDRAM timing
4249
4250- CONFIG_SYS_MAMR_PTA:
4251		periodic timer for refresh
4252
4253- CONFIG_SYS_DER:	Debug Event Register (37-47)
4254
4255- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4256  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4257  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4258  CONFIG_SYS_BR1_PRELIM:
4259		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4260
4261- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4262  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4263  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4264		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4265
4266- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4267  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4268		Machine Mode Register and Memory Periodic Timer
4269		Prescaler definitions (SDRAM timing)
4270
4271- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4272		enable I2C microcode relocation patch (MPC8xx);
4273		define relocation offset in DPRAM [DSP2]
4274
4275- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4276		enable SMC microcode relocation patch (MPC8xx);
4277		define relocation offset in DPRAM [SMC1]
4278
4279- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4280		enable SPI microcode relocation patch (MPC8xx);
4281		define relocation offset in DPRAM [SCC4]
4282
4283- CONFIG_SYS_USE_OSCCLK:
4284		Use OSCM clock mode on MBX8xx board. Be careful,
4285		wrong setting might damage your board. Read
4286		doc/README.MBX before setting this variable!
4287
4288- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4289		Offset of the bootmode word in DPRAM used by post
4290		(Power On Self Tests). This definition overrides
4291		#define'd default value in commproc.h resp.
4292		cpm_8260.h.
4293
4294- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4295  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4296  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4297  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4298  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4299  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4300  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4301  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4302		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4303
4304- CONFIG_PCI_DISABLE_PCIE:
4305		Disable PCI-Express on systems where it is supported but not
4306		required.
4307
4308- CONFIG_PCI_ENUM_ONLY
4309		Only scan through and get the devices on the busses.
4310		Don't do any setup work, presumably because someone or
4311		something has already done it, and we don't need to do it
4312		a second time.	Useful for platforms that are pre-booted
4313		by coreboot or similar.
4314
4315- CONFIG_PCI_INDIRECT_BRIDGE:
4316		Enable support for indirect PCI bridges.
4317
4318- CONFIG_SYS_SRIO:
4319		Chip has SRIO or not
4320
4321- CONFIG_SRIO1:
4322		Board has SRIO 1 port available
4323
4324- CONFIG_SRIO2:
4325		Board has SRIO 2 port available
4326
4327- CONFIG_SRIO_PCIE_BOOT_MASTER
4328		Board can support master function for Boot from SRIO and PCIE
4329
4330- CONFIG_SYS_SRIOn_MEM_VIRT:
4331		Virtual Address of SRIO port 'n' memory region
4332
4333- CONFIG_SYS_SRIOn_MEM_PHYS:
4334		Physical Address of SRIO port 'n' memory region
4335
4336- CONFIG_SYS_SRIOn_MEM_SIZE:
4337		Size of SRIO port 'n' memory region
4338
4339- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4340		Defined to tell the NAND controller that the NAND chip is using
4341		a 16 bit bus.
4342		Not all NAND drivers use this symbol.
4343		Example of drivers that use it:
4344		- drivers/mtd/nand/ndfc.c
4345		- drivers/mtd/nand/mxc_nand.c
4346
4347- CONFIG_SYS_NDFC_EBC0_CFG
4348		Sets the EBC0_CFG register for the NDFC. If not defined
4349		a default value will be used.
4350
4351- CONFIG_SPD_EEPROM
4352		Get DDR timing information from an I2C EEPROM. Common
4353		with pluggable memory modules such as SODIMMs
4354
4355  SPD_EEPROM_ADDRESS
4356		I2C address of the SPD EEPROM
4357
4358- CONFIG_SYS_SPD_BUS_NUM
4359		If SPD EEPROM is on an I2C bus other than the first
4360		one, specify here. Note that the value must resolve
4361		to something your driver can deal with.
4362
4363- CONFIG_SYS_DDR_RAW_TIMING
4364		Get DDR timing information from other than SPD. Common with
4365		soldered DDR chips onboard without SPD. DDR raw timing
4366		parameters are extracted from datasheet and hard-coded into
4367		header files or board specific files.
4368
4369- CONFIG_FSL_DDR_INTERACTIVE
4370		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4371
4372- CONFIG_SYS_83XX_DDR_USES_CS0
4373		Only for 83xx systems. If specified, then DDR should
4374		be configured using CS0 and CS1 instead of CS2 and CS3.
4375
4376- CONFIG_ETHER_ON_FEC[12]
4377		Define to enable FEC[12] on a 8xx series processor.
4378
4379- CONFIG_FEC[12]_PHY
4380		Define to the hardcoded PHY address which corresponds
4381		to the given FEC; i. e.
4382			#define CONFIG_FEC1_PHY 4
4383		means that the PHY with address 4 is connected to FEC1
4384
4385		When set to -1, means to probe for first available.
4386
4387- CONFIG_FEC[12]_PHY_NORXERR
4388		The PHY does not have a RXERR line (RMII only).
4389		(so program the FEC to ignore it).
4390
4391- CONFIG_RMII
4392		Enable RMII mode for all FECs.
4393		Note that this is a global option, we can't
4394		have one FEC in standard MII mode and another in RMII mode.
4395
4396- CONFIG_CRC32_VERIFY
4397		Add a verify option to the crc32 command.
4398		The syntax is:
4399
4400		=> crc32 -v <address> <count> <crc32>
4401
4402		Where address/count indicate a memory area
4403		and crc32 is the correct crc32 which the
4404		area should have.
4405
4406- CONFIG_LOOPW
4407		Add the "loopw" memory command. This only takes effect if
4408		the memory commands are activated globally (CONFIG_CMD_MEM).
4409
4410- CONFIG_MX_CYCLIC
4411		Add the "mdc" and "mwc" memory commands. These are cyclic
4412		"md/mw" commands.
4413		Examples:
4414
4415		=> mdc.b 10 4 500
4416		This command will print 4 bytes (10,11,12,13) each 500 ms.
4417
4418		=> mwc.l 100 12345678 10
4419		This command will write 12345678 to address 100 all 10 ms.
4420
4421		This only takes effect if the memory commands are activated
4422		globally (CONFIG_CMD_MEM).
4423
4424- CONFIG_SKIP_LOWLEVEL_INIT
4425		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4426		low level initializations (like setting up the memory
4427		controller) are omitted and/or U-Boot does not
4428		relocate itself into RAM.
4429
4430		Normally this variable MUST NOT be defined. The only
4431		exception is when U-Boot is loaded (to RAM) by some
4432		other boot loader or by a debugger which performs
4433		these initializations itself.
4434
4435- CONFIG_SPL_BUILD
4436		Modifies the behaviour of start.S when compiling a loader
4437		that is executed before the actual U-Boot. E.g. when
4438		compiling a NAND SPL.
4439
4440- CONFIG_TPL_BUILD
4441		Modifies the behaviour of start.S  when compiling a loader
4442		that is executed after the SPL and before the actual U-Boot.
4443		It is loaded by the SPL.
4444
4445- CONFIG_SYS_MPC85XX_NO_RESETVEC
4446		Only for 85xx systems. If this variable is specified, the section
4447		.resetvec is not kept and the section .bootpg is placed in the
4448		previous 4k of the .text section.
4449
4450- CONFIG_ARCH_MAP_SYSMEM
4451		Generally U-Boot (and in particular the md command) uses
4452		effective address. It is therefore not necessary to regard
4453		U-Boot address as virtual addresses that need to be translated
4454		to physical addresses. However, sandbox requires this, since
4455		it maintains its own little RAM buffer which contains all
4456		addressable memory. This option causes some memory accesses
4457		to be mapped through map_sysmem() / unmap_sysmem().
4458
4459- CONFIG_USE_ARCH_MEMCPY
4460  CONFIG_USE_ARCH_MEMSET
4461		If these options are used a optimized version of memcpy/memset will
4462		be used if available. These functions may be faster under some
4463		conditions but may increase the binary size.
4464
4465- CONFIG_X86_RESET_VECTOR
4466		If defined, the x86 reset vector code is included. This is not
4467		needed when U-Boot is running from Coreboot.
4468
4469- CONFIG_SYS_MPUCLK
4470		Defines the MPU clock speed (in MHz).
4471
4472		NOTE : currently only supported on AM335x platforms.
4473
4474- CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
4475		Enables the RTC32K OSC on AM33xx based plattforms
4476
4477Freescale QE/FMAN Firmware Support:
4478-----------------------------------
4479
4480The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4481loading of "firmware", which is encoded in the QE firmware binary format.
4482This firmware often needs to be loaded during U-Boot booting, so macros
4483are used to identify the storage device (NOR flash, SPI, etc) and the address
4484within that device.
4485
4486- CONFIG_SYS_QE_FMAN_FW_ADDR
4487	The address in the storage device where the firmware is located.  The
4488	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4489	is also specified.
4490
4491- CONFIG_SYS_QE_FMAN_FW_LENGTH
4492	The maximum possible size of the firmware.  The firmware binary format
4493	has a field that specifies the actual size of the firmware, but it
4494	might not be possible to read any part of the firmware unless some
4495	local storage is allocated to hold the entire firmware first.
4496
4497- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4498	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4499	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4500	virtual address in NOR flash.
4501
4502- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4503	Specifies that QE/FMAN firmware is located in NAND flash.
4504	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4505
4506- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4507	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4508	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4509
4510- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
4511	Specifies that QE/FMAN firmware is located on the primary SPI
4512	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4513
4514- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4515	Specifies that QE/FMAN firmware is located in the remote (master)
4516	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4517	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4518	window->master inbound window->master LAW->the ucode address in
4519	master's memory space.
4520
4521Building the Software:
4522======================
4523
4524Building U-Boot has been tested in several native build environments
4525and in many different cross environments. Of course we cannot support
4526all possibly existing versions of cross development tools in all
4527(potentially obsolete) versions. In case of tool chain problems we
4528recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4529which is extensively used to build and test U-Boot.
4530
4531If you are not using a native environment, it is assumed that you
4532have GNU cross compiling tools available in your path. In this case,
4533you must set the environment variable CROSS_COMPILE in your shell.
4534Note that no changes to the Makefile or any other source files are
4535necessary. For example using the ELDK on a 4xx CPU, please enter:
4536
4537	$ CROSS_COMPILE=ppc_4xx-
4538	$ export CROSS_COMPILE
4539
4540Note: If you wish to generate Windows versions of the utilities in
4541      the tools directory you can use the MinGW toolchain
4542      (http://www.mingw.org).  Set your HOST tools to the MinGW
4543      toolchain and execute 'make tools'.  For example:
4544
4545       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4546
4547      Binaries such as tools/mkimage.exe will be created which can
4548      be executed on computers running Windows.
4549
4550U-Boot is intended to be simple to build. After installing the
4551sources you must configure U-Boot for one specific board type. This
4552is done by typing:
4553
4554	make NAME_config
4555
4556where "NAME_config" is the name of one of the existing configu-
4557rations; see boards.cfg for supported names.
4558
4559Note: for some board special configuration names may exist; check if
4560      additional information is available from the board vendor; for
4561      instance, the TQM823L systems are available without (standard)
4562      or with LCD support. You can select such additional "features"
4563      when choosing the configuration, i. e.
4564
4565      make TQM823L_config
4566	- will configure for a plain TQM823L, i. e. no LCD support
4567
4568      make TQM823L_LCD_config
4569	- will configure for a TQM823L with U-Boot console on LCD
4570
4571      etc.
4572
4573
4574Finally, type "make all", and you should get some working U-Boot
4575images ready for download to / installation on your system:
4576
4577- "u-boot.bin" is a raw binary image
4578- "u-boot" is an image in ELF binary format
4579- "u-boot.srec" is in Motorola S-Record format
4580
4581By default the build is performed locally and the objects are saved
4582in the source directory. One of the two methods can be used to change
4583this behavior and build U-Boot to some external directory:
4584
45851. Add O= to the make command line invocations:
4586
4587	make O=/tmp/build distclean
4588	make O=/tmp/build NAME_config
4589	make O=/tmp/build all
4590
45912. Set environment variable BUILD_DIR to point to the desired location:
4592
4593	export BUILD_DIR=/tmp/build
4594	make distclean
4595	make NAME_config
4596	make all
4597
4598Note that the command line "O=" setting overrides the BUILD_DIR environment
4599variable.
4600
4601
4602Please be aware that the Makefiles assume you are using GNU make, so
4603for instance on NetBSD you might need to use "gmake" instead of
4604native "make".
4605
4606
4607If the system board that you have is not listed, then you will need
4608to port U-Boot to your hardware platform. To do this, follow these
4609steps:
4610
46111.  Add a new configuration option for your board to the toplevel
4612    "boards.cfg" file, using the existing entries as examples.
4613    Follow the instructions there to keep the boards in order.
46142.  Create a new directory to hold your board specific code. Add any
4615    files you need. In your board directory, you will need at least
4616    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
46173.  Create a new configuration file "include/configs/<board>.h" for
4618    your board
46193.  If you're porting U-Boot to a new CPU, then also create a new
4620    directory to hold your CPU specific code. Add any files you need.
46214.  Run "make <board>_config" with your new name.
46225.  Type "make", and you should get a working "u-boot.srec" file
4623    to be installed on your target system.
46246.  Debug and solve any problems that might arise.
4625    [Of course, this last step is much harder than it sounds.]
4626
4627
4628Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4629==============================================================
4630
4631If you have modified U-Boot sources (for instance added a new board
4632or support for new devices, a new CPU, etc.) you are expected to
4633provide feedback to the other developers. The feedback normally takes
4634the form of a "patch", i. e. a context diff against a certain (latest
4635official or latest in the git repository) version of U-Boot sources.
4636
4637But before you submit such a patch, please verify that your modifi-
4638cation did not break existing code. At least make sure that *ALL* of
4639the supported boards compile WITHOUT ANY compiler warnings. To do so,
4640just run the "MAKEALL" script, which will configure and build U-Boot
4641for ALL supported system. Be warned, this will take a while. You can
4642select which (cross) compiler to use by passing a `CROSS_COMPILE'
4643environment variable to the script, i. e. to use the ELDK cross tools
4644you can type
4645
4646	CROSS_COMPILE=ppc_8xx- MAKEALL
4647
4648or to build on a native PowerPC system you can type
4649
4650	CROSS_COMPILE=' ' MAKEALL
4651
4652When using the MAKEALL script, the default behaviour is to build
4653U-Boot in the source directory. This location can be changed by
4654setting the BUILD_DIR environment variable. Also, for each target
4655built, the MAKEALL script saves two log files (<target>.ERR and
4656<target>.MAKEALL) in the <source dir>/LOG directory. This default
4657location can be changed by setting the MAKEALL_LOGDIR environment
4658variable. For example:
4659
4660	export BUILD_DIR=/tmp/build
4661	export MAKEALL_LOGDIR=/tmp/log
4662	CROSS_COMPILE=ppc_8xx- MAKEALL
4663
4664With the above settings build objects are saved in the /tmp/build,
4665log files are saved in the /tmp/log and the source tree remains clean
4666during the whole build process.
4667
4668
4669See also "U-Boot Porting Guide" below.
4670
4671
4672Monitor Commands - Overview:
4673============================
4674
4675go	- start application at address 'addr'
4676run	- run commands in an environment variable
4677bootm	- boot application image from memory
4678bootp	- boot image via network using BootP/TFTP protocol
4679bootz   - boot zImage from memory
4680tftpboot- boot image via network using TFTP protocol
4681	       and env variables "ipaddr" and "serverip"
4682	       (and eventually "gatewayip")
4683tftpput - upload a file via network using TFTP protocol
4684rarpboot- boot image via network using RARP/TFTP protocol
4685diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4686loads	- load S-Record file over serial line
4687loadb	- load binary file over serial line (kermit mode)
4688md	- memory display
4689mm	- memory modify (auto-incrementing)
4690nm	- memory modify (constant address)
4691mw	- memory write (fill)
4692cp	- memory copy
4693cmp	- memory compare
4694crc32	- checksum calculation
4695i2c	- I2C sub-system
4696sspi	- SPI utility commands
4697base	- print or set address offset
4698printenv- print environment variables
4699setenv	- set environment variables
4700saveenv - save environment variables to persistent storage
4701protect - enable or disable FLASH write protection
4702erase	- erase FLASH memory
4703flinfo	- print FLASH memory information
4704nand	- NAND memory operations (see doc/README.nand)
4705bdinfo	- print Board Info structure
4706iminfo	- print header information for application image
4707coninfo - print console devices and informations
4708ide	- IDE sub-system
4709loop	- infinite loop on address range
4710loopw	- infinite write loop on address range
4711mtest	- simple RAM test
4712icache	- enable or disable instruction cache
4713dcache	- enable or disable data cache
4714reset	- Perform RESET of the CPU
4715echo	- echo args to console
4716version - print monitor version
4717help	- print online help
4718?	- alias for 'help'
4719
4720
4721Monitor Commands - Detailed Description:
4722========================================
4723
4724TODO.
4725
4726For now: just type "help <command>".
4727
4728
4729Environment Variables:
4730======================
4731
4732U-Boot supports user configuration using Environment Variables which
4733can be made persistent by saving to Flash memory.
4734
4735Environment Variables are set using "setenv", printed using
4736"printenv", and saved to Flash using "saveenv". Using "setenv"
4737without a value can be used to delete a variable from the
4738environment. As long as you don't save the environment you are
4739working with an in-memory copy. In case the Flash area containing the
4740environment is erased by accident, a default environment is provided.
4741
4742Some configuration options can be set using Environment Variables.
4743
4744List of environment variables (most likely not complete):
4745
4746  baudrate	- see CONFIG_BAUDRATE
4747
4748  bootdelay	- see CONFIG_BOOTDELAY
4749
4750  bootcmd	- see CONFIG_BOOTCOMMAND
4751
4752  bootargs	- Boot arguments when booting an RTOS image
4753
4754  bootfile	- Name of the image to load with TFTP
4755
4756  bootm_low	- Memory range available for image processing in the bootm
4757		  command can be restricted. This variable is given as
4758		  a hexadecimal number and defines lowest address allowed
4759		  for use by the bootm command. See also "bootm_size"
4760		  environment variable. Address defined by "bootm_low" is
4761		  also the base of the initial memory mapping for the Linux
4762		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
4763		  bootm_mapsize.
4764
4765  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
4766		  This variable is given as a hexadecimal number and it
4767		  defines the size of the memory region starting at base
4768		  address bootm_low that is accessible by the Linux kernel
4769		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
4770		  as the default value if it is defined, and bootm_size is
4771		  used otherwise.
4772
4773  bootm_size	- Memory range available for image processing in the bootm
4774		  command can be restricted. This variable is given as
4775		  a hexadecimal number and defines the size of the region
4776		  allowed for use by the bootm command. See also "bootm_low"
4777		  environment variable.
4778
4779  updatefile	- Location of the software update file on a TFTP server, used
4780		  by the automatic software update feature. Please refer to
4781		  documentation in doc/README.update for more details.
4782
4783  autoload	- if set to "no" (any string beginning with 'n'),
4784		  "bootp" will just load perform a lookup of the
4785		  configuration from the BOOTP server, but not try to
4786		  load any image using TFTP
4787
4788  autostart	- if set to "yes", an image loaded using the "bootp",
4789		  "rarpboot", "tftpboot" or "diskboot" commands will
4790		  be automatically started (by internally calling
4791		  "bootm")
4792
4793		  If set to "no", a standalone image passed to the
4794		  "bootm" command will be copied to the load address
4795		  (and eventually uncompressed), but NOT be started.
4796		  This can be used to load and uncompress arbitrary
4797		  data.
4798
4799  fdt_high	- if set this restricts the maximum address that the
4800		  flattened device tree will be copied into upon boot.
4801		  For example, if you have a system with 1 GB memory
4802		  at physical address 0x10000000, while Linux kernel
4803		  only recognizes the first 704 MB as low memory, you
4804		  may need to set fdt_high as 0x3C000000 to have the
4805		  device tree blob be copied to the maximum address
4806		  of the 704 MB low memory, so that Linux kernel can
4807		  access it during the boot procedure.
4808
4809		  If this is set to the special value 0xFFFFFFFF then
4810		  the fdt will not be copied at all on boot.  For this
4811		  to work it must reside in writable memory, have
4812		  sufficient padding on the end of it for u-boot to
4813		  add the information it needs into it, and the memory
4814		  must be accessible by the kernel.
4815
4816  fdtcontroladdr- if set this is the address of the control flattened
4817		  device tree used by U-Boot when CONFIG_OF_CONTROL is
4818		  defined.
4819
4820  i2cfast	- (PPC405GP|PPC405EP only)
4821		  if set to 'y' configures Linux I2C driver for fast
4822		  mode (400kHZ). This environment variable is used in
4823		  initialization code. So, for changes to be effective
4824		  it must be saved and board must be reset.
4825
4826  initrd_high	- restrict positioning of initrd images:
4827		  If this variable is not set, initrd images will be
4828		  copied to the highest possible address in RAM; this
4829		  is usually what you want since it allows for
4830		  maximum initrd size. If for some reason you want to
4831		  make sure that the initrd image is loaded below the
4832		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
4833		  variable to a value of "no" or "off" or "0".
4834		  Alternatively, you can set it to a maximum upper
4835		  address to use (U-Boot will still check that it
4836		  does not overwrite the U-Boot stack and data).
4837
4838		  For instance, when you have a system with 16 MB
4839		  RAM, and want to reserve 4 MB from use by Linux,
4840		  you can do this by adding "mem=12M" to the value of
4841		  the "bootargs" variable. However, now you must make
4842		  sure that the initrd image is placed in the first
4843		  12 MB as well - this can be done with
4844
4845		  setenv initrd_high 00c00000
4846
4847		  If you set initrd_high to 0xFFFFFFFF, this is an
4848		  indication to U-Boot that all addresses are legal
4849		  for the Linux kernel, including addresses in flash
4850		  memory. In this case U-Boot will NOT COPY the
4851		  ramdisk at all. This may be useful to reduce the
4852		  boot time on your system, but requires that this
4853		  feature is supported by your Linux kernel.
4854
4855  ipaddr	- IP address; needed for tftpboot command
4856
4857  loadaddr	- Default load address for commands like "bootp",
4858		  "rarpboot", "tftpboot", "loadb" or "diskboot"
4859
4860  loads_echo	- see CONFIG_LOADS_ECHO
4861
4862  serverip	- TFTP server IP address; needed for tftpboot command
4863
4864  bootretry	- see CONFIG_BOOT_RETRY_TIME
4865
4866  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
4867
4868  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
4869
4870  ethprime	- controls which interface is used first.
4871
4872  ethact	- controls which interface is currently active.
4873		  For example you can do the following
4874
4875		  => setenv ethact FEC
4876		  => ping 192.168.0.1 # traffic sent on FEC
4877		  => setenv ethact SCC
4878		  => ping 10.0.0.1 # traffic sent on SCC
4879
4880  ethrotate	- When set to "no" U-Boot does not go through all
4881		  available network interfaces.
4882		  It just stays at the currently selected interface.
4883
4884  netretry	- When set to "no" each network operation will
4885		  either succeed or fail without retrying.
4886		  When set to "once" the network operation will
4887		  fail when all the available network interfaces
4888		  are tried once without success.
4889		  Useful on scripts which control the retry operation
4890		  themselves.
4891
4892  npe_ucode	- set load address for the NPE microcode
4893
4894  silent_linux  - If set then linux will be told to boot silently, by
4895		  changing the console to be empty. If "yes" it will be
4896		  made silent. If "no" it will not be made silent. If
4897		  unset, then it will be made silent if the U-Boot console
4898		  is silent.
4899
4900  tftpsrcport	- If this is set, the value is used for TFTP's
4901		  UDP source port.
4902
4903  tftpdstport	- If this is set, the value is used for TFTP's UDP
4904		  destination port instead of the Well Know Port 69.
4905
4906  tftpblocksize - Block size to use for TFTP transfers; if not set,
4907		  we use the TFTP server's default block size
4908
4909  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
4910		  seconds, minimum value is 1000 = 1 second). Defines
4911		  when a packet is considered to be lost so it has to
4912		  be retransmitted. The default is 5000 = 5 seconds.
4913		  Lowering this value may make downloads succeed
4914		  faster in networks with high packet loss rates or
4915		  with unreliable TFTP servers.
4916
4917  vlan		- When set to a value < 4095 the traffic over
4918		  Ethernet is encapsulated/received over 802.1q
4919		  VLAN tagged frames.
4920
4921The following image location variables contain the location of images
4922used in booting. The "Image" column gives the role of the image and is
4923not an environment variable name. The other columns are environment
4924variable names. "File Name" gives the name of the file on a TFTP
4925server, "RAM Address" gives the location in RAM the image will be
4926loaded to, and "Flash Location" gives the image's address in NOR
4927flash or offset in NAND flash.
4928
4929*Note* - these variables don't have to be defined for all boards, some
4930boards currenlty use other variables for these purposes, and some
4931boards use these variables for other purposes.
4932
4933Image		    File Name	     RAM Address       Flash Location
4934-----		    ---------	     -----------       --------------
4935u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
4936Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
4937device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
4938ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
4939
4940The following environment variables may be used and automatically
4941updated by the network boot commands ("bootp" and "rarpboot"),
4942depending the information provided by your boot server:
4943
4944  bootfile	- see above
4945  dnsip		- IP address of your Domain Name Server
4946  dnsip2	- IP address of your secondary Domain Name Server
4947  gatewayip	- IP address of the Gateway (Router) to use
4948  hostname	- Target hostname
4949  ipaddr	- see above
4950  netmask	- Subnet Mask
4951  rootpath	- Pathname of the root filesystem on the NFS server
4952  serverip	- see above
4953
4954
4955There are two special Environment Variables:
4956
4957  serial#	- contains hardware identification information such
4958		  as type string and/or serial number
4959  ethaddr	- Ethernet address
4960
4961These variables can be set only once (usually during manufacturing of
4962the board). U-Boot refuses to delete or overwrite these variables
4963once they have been set once.
4964
4965
4966Further special Environment Variables:
4967
4968  ver		- Contains the U-Boot version string as printed
4969		  with the "version" command. This variable is
4970		  readonly (see CONFIG_VERSION_VARIABLE).
4971
4972
4973Please note that changes to some configuration parameters may take
4974only effect after the next boot (yes, that's just like Windoze :-).
4975
4976
4977Callback functions for environment variables:
4978---------------------------------------------
4979
4980For some environment variables, the behavior of u-boot needs to change
4981when their values are changed.  This functionailty allows functions to
4982be associated with arbitrary variables.  On creation, overwrite, or
4983deletion, the callback will provide the opportunity for some side
4984effect to happen or for the change to be rejected.
4985
4986The callbacks are named and associated with a function using the
4987U_BOOT_ENV_CALLBACK macro in your board or driver code.
4988
4989These callbacks are associated with variables in one of two ways.  The
4990static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
4991in the board configuration to a string that defines a list of
4992associations.  The list must be in the following format:
4993
4994	entry = variable_name[:callback_name]
4995	list = entry[,list]
4996
4997If the callback name is not specified, then the callback is deleted.
4998Spaces are also allowed anywhere in the list.
4999
5000Callbacks can also be associated by defining the ".callbacks" variable
5001with the same list format above.  Any association in ".callbacks" will
5002override any association in the static list. You can define
5003CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
5004".callbacks" envirnoment variable in the default or embedded environment.
5005
5006
5007Command Line Parsing:
5008=====================
5009
5010There are two different command line parsers available with U-Boot:
5011the old "simple" one, and the much more powerful "hush" shell:
5012
5013Old, simple command line parser:
5014--------------------------------
5015
5016- supports environment variables (through setenv / saveenv commands)
5017- several commands on one line, separated by ';'
5018- variable substitution using "... ${name} ..." syntax
5019- special characters ('$', ';') can be escaped by prefixing with '\',
5020  for example:
5021	setenv bootcmd bootm \${address}
5022- You can also escape text by enclosing in single apostrophes, for example:
5023	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
5024
5025Hush shell:
5026-----------
5027
5028- similar to Bourne shell, with control structures like
5029  if...then...else...fi, for...do...done; while...do...done,
5030  until...do...done, ...
5031- supports environment ("global") variables (through setenv / saveenv
5032  commands) and local shell variables (through standard shell syntax
5033  "name=value"); only environment variables can be used with "run"
5034  command
5035
5036General rules:
5037--------------
5038
5039(1) If a command line (or an environment variable executed by a "run"
5040    command) contains several commands separated by semicolon, and
5041    one of these commands fails, then the remaining commands will be
5042    executed anyway.
5043
5044(2) If you execute several variables with one call to run (i. e.
5045    calling run with a list of variables as arguments), any failing
5046    command will cause "run" to terminate, i. e. the remaining
5047    variables are not executed.
5048
5049Note for Redundant Ethernet Interfaces:
5050=======================================
5051
5052Some boards come with redundant Ethernet interfaces; U-Boot supports
5053such configurations and is capable of automatic selection of a
5054"working" interface when needed. MAC assignment works as follows:
5055
5056Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
5057MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
5058"eth1addr" (=>eth1), "eth2addr", ...
5059
5060If the network interface stores some valid MAC address (for instance
5061in SROM), this is used as default address if there is NO correspon-
5062ding setting in the environment; if the corresponding environment
5063variable is set, this overrides the settings in the card; that means:
5064
5065o If the SROM has a valid MAC address, and there is no address in the
5066  environment, the SROM's address is used.
5067
5068o If there is no valid address in the SROM, and a definition in the
5069  environment exists, then the value from the environment variable is
5070  used.
5071
5072o If both the SROM and the environment contain a MAC address, and
5073  both addresses are the same, this MAC address is used.
5074
5075o If both the SROM and the environment contain a MAC address, and the
5076  addresses differ, the value from the environment is used and a
5077  warning is printed.
5078
5079o If neither SROM nor the environment contain a MAC address, an error
5080  is raised.
5081
5082If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
5083will be programmed into hardware as part of the initialization process.	 This
5084may be skipped by setting the appropriate 'ethmacskip' environment variable.
5085The naming convention is as follows:
5086"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
5087
5088Image Formats:
5089==============
5090
5091U-Boot is capable of booting (and performing other auxiliary operations on)
5092images in two formats:
5093
5094New uImage format (FIT)
5095-----------------------
5096
5097Flexible and powerful format based on Flattened Image Tree -- FIT (similar
5098to Flattened Device Tree). It allows the use of images with multiple
5099components (several kernels, ramdisks, etc.), with contents protected by
5100SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
5101
5102
5103Old uImage format
5104-----------------
5105
5106Old image format is based on binary files which can be basically anything,
5107preceded by a special header; see the definitions in include/image.h for
5108details; basically, the header defines the following image properties:
5109
5110* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
5111  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
5112  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
5113  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
5114  INTEGRITY).
5115* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
5116  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
5117  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
5118* Compression Type (uncompressed, gzip, bzip2)
5119* Load Address
5120* Entry Point
5121* Image Name
5122* Image Timestamp
5123
5124The header is marked by a special Magic Number, and both the header
5125and the data portions of the image are secured against corruption by
5126CRC32 checksums.
5127
5128
5129Linux Support:
5130==============
5131
5132Although U-Boot should support any OS or standalone application
5133easily, the main focus has always been on Linux during the design of
5134U-Boot.
5135
5136U-Boot includes many features that so far have been part of some
5137special "boot loader" code within the Linux kernel. Also, any
5138"initrd" images to be used are no longer part of one big Linux image;
5139instead, kernel and "initrd" are separate images. This implementation
5140serves several purposes:
5141
5142- the same features can be used for other OS or standalone
5143  applications (for instance: using compressed images to reduce the
5144  Flash memory footprint)
5145
5146- it becomes much easier to port new Linux kernel versions because
5147  lots of low-level, hardware dependent stuff are done by U-Boot
5148
5149- the same Linux kernel image can now be used with different "initrd"
5150  images; of course this also means that different kernel images can
5151  be run with the same "initrd". This makes testing easier (you don't
5152  have to build a new "zImage.initrd" Linux image when you just
5153  change a file in your "initrd"). Also, a field-upgrade of the
5154  software is easier now.
5155
5156
5157Linux HOWTO:
5158============
5159
5160Porting Linux to U-Boot based systems:
5161---------------------------------------
5162
5163U-Boot cannot save you from doing all the necessary modifications to
5164configure the Linux device drivers for use with your target hardware
5165(no, we don't intend to provide a full virtual machine interface to
5166Linux :-).
5167
5168But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
5169
5170Just make sure your machine specific header file (for instance
5171include/asm-ppc/tqm8xx.h) includes the same definition of the Board
5172Information structure as we define in include/asm-<arch>/u-boot.h,
5173and make sure that your definition of IMAP_ADDR uses the same value
5174as your U-Boot configuration in CONFIG_SYS_IMMR.
5175
5176
5177Configuring the Linux kernel:
5178-----------------------------
5179
5180No specific requirements for U-Boot. Make sure you have some root
5181device (initial ramdisk, NFS) for your target system.
5182
5183
5184Building a Linux Image:
5185-----------------------
5186
5187With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5188not used. If you use recent kernel source, a new build target
5189"uImage" will exist which automatically builds an image usable by
5190U-Boot. Most older kernels also have support for a "pImage" target,
5191which was introduced for our predecessor project PPCBoot and uses a
5192100% compatible format.
5193
5194Example:
5195
5196	make TQM850L_config
5197	make oldconfig
5198	make dep
5199	make uImage
5200
5201The "uImage" build target uses a special tool (in 'tools/mkimage') to
5202encapsulate a compressed Linux kernel image with header	 information,
5203CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5204
5205* build a standard "vmlinux" kernel image (in ELF binary format):
5206
5207* convert the kernel into a raw binary image:
5208
5209	${CROSS_COMPILE}-objcopy -O binary \
5210				 -R .note -R .comment \
5211				 -S vmlinux linux.bin
5212
5213* compress the binary image:
5214
5215	gzip -9 linux.bin
5216
5217* package compressed binary image for U-Boot:
5218
5219	mkimage -A ppc -O linux -T kernel -C gzip \
5220		-a 0 -e 0 -n "Linux Kernel Image" \
5221		-d linux.bin.gz uImage
5222
5223
5224The "mkimage" tool can also be used to create ramdisk images for use
5225with U-Boot, either separated from the Linux kernel image, or
5226combined into one file. "mkimage" encapsulates the images with a 64
5227byte header containing information about target architecture,
5228operating system, image type, compression method, entry points, time
5229stamp, CRC32 checksums, etc.
5230
5231"mkimage" can be called in two ways: to verify existing images and
5232print the header information, or to build new images.
5233
5234In the first form (with "-l" option) mkimage lists the information
5235contained in the header of an existing U-Boot image; this includes
5236checksum verification:
5237
5238	tools/mkimage -l image
5239	  -l ==> list image header information
5240
5241The second form (with "-d" option) is used to build a U-Boot image
5242from a "data file" which is used as image payload:
5243
5244	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5245		      -n name -d data_file image
5246	  -A ==> set architecture to 'arch'
5247	  -O ==> set operating system to 'os'
5248	  -T ==> set image type to 'type'
5249	  -C ==> set compression type 'comp'
5250	  -a ==> set load address to 'addr' (hex)
5251	  -e ==> set entry point to 'ep' (hex)
5252	  -n ==> set image name to 'name'
5253	  -d ==> use image data from 'datafile'
5254
5255Right now, all Linux kernels for PowerPC systems use the same load
5256address (0x00000000), but the entry point address depends on the
5257kernel version:
5258
5259- 2.2.x kernels have the entry point at 0x0000000C,
5260- 2.3.x and later kernels have the entry point at 0x00000000.
5261
5262So a typical call to build a U-Boot image would read:
5263
5264	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5265	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5266	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5267	> 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
5275To verify the contents of the image (or check for corruption):
5276
5277	-> tools/mkimage -l examples/uImage.TQM850L
5278	Image Name:   2.4.4 kernel for TQM850L
5279	Created:      Wed Jul 19 02:34:59 2000
5280	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5281	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5282	Load Address: 0x00000000
5283	Entry Point:  0x00000000
5284
5285NOTE: for embedded systems where boot time is critical you can trade
5286speed for memory and install an UNCOMPRESSED image instead: this
5287needs more space in Flash, but boots much faster since it does not
5288need to be uncompressed:
5289
5290	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5291	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5292	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5293	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5294	> examples/uImage.TQM850L-uncompressed
5295	Image Name:   2.4.4 kernel for TQM850L
5296	Created:      Wed Jul 19 02:34:59 2000
5297	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5298	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5299	Load Address: 0x00000000
5300	Entry Point:  0x00000000
5301
5302
5303Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5304when your kernel is intended to use an initial ramdisk:
5305
5306	-> tools/mkimage -n 'Simple Ramdisk Image' \
5307	> -A ppc -O linux -T ramdisk -C gzip \
5308	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5309	Image Name:   Simple Ramdisk Image
5310	Created:      Wed Jan 12 14:01:50 2000
5311	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5312	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5313	Load Address: 0x00000000
5314	Entry Point:  0x00000000
5315
5316The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
5317option performs the converse operation of the mkimage's second form (the "-d"
5318option). Given an image built by mkimage, the dumpimage extracts a "data file"
5319from the image:
5320
5321	tools/dumpimage -i image -p position data_file
5322	  -i ==> extract from the 'image' a specific 'data_file', \
5323	   indexed by 'position'
5324
5325
5326Installing a Linux Image:
5327-------------------------
5328
5329To downloading a U-Boot image over the serial (console) interface,
5330you must convert the image to S-Record format:
5331
5332	objcopy -I binary -O srec examples/image examples/image.srec
5333
5334The 'objcopy' does not understand the information in the U-Boot
5335image header, so the resulting S-Record file will be relative to
5336address 0x00000000. To load it to a given address, you need to
5337specify the target address as 'offset' parameter with the 'loads'
5338command.
5339
5340Example: install the image to address 0x40100000 (which on the
5341TQM8xxL is in the first Flash bank):
5342
5343	=> erase 40100000 401FFFFF
5344
5345	.......... done
5346	Erased 8 sectors
5347
5348	=> loads 40100000
5349	## Ready for S-Record download ...
5350	~>examples/image.srec
5351	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5352	...
5353	15989 15990 15991 15992
5354	[file transfer complete]
5355	[connected]
5356	## Start Addr = 0x00000000
5357
5358
5359You can check the success of the download using the 'iminfo' command;
5360this includes a checksum verification so you can be sure no data
5361corruption happened:
5362
5363	=> imi 40100000
5364
5365	## Checking Image at 40100000 ...
5366	   Image Name:	 2.2.13 for initrd on TQM850L
5367	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5368	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5369	   Load Address: 00000000
5370	   Entry Point:	 0000000c
5371	   Verifying Checksum ... OK
5372
5373
5374Boot Linux:
5375-----------
5376
5377The "bootm" command is used to boot an application that is stored in
5378memory (RAM or Flash). In case of a Linux kernel image, the contents
5379of the "bootargs" environment variable is passed to the kernel as
5380parameters. You can check and modify this variable using the
5381"printenv" and "setenv" commands:
5382
5383
5384	=> printenv bootargs
5385	bootargs=root=/dev/ram
5386
5387	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5388
5389	=> printenv bootargs
5390	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5391
5392	=> bootm 40020000
5393	## Booting Linux kernel at 40020000 ...
5394	   Image Name:	 2.2.13 for NFS on TQM850L
5395	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5396	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5397	   Load Address: 00000000
5398	   Entry Point:	 0000000c
5399	   Verifying Checksum ... OK
5400	   Uncompressing Kernel Image ... OK
5401	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
5402	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5403	time_init: decrementer frequency = 187500000/60
5404	Calibrating delay loop... 49.77 BogoMIPS
5405	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5406	...
5407
5408If you want to boot a Linux kernel with initial RAM disk, you pass
5409the memory addresses of both the kernel and the initrd image (PPBCOOT
5410format!) to the "bootm" command:
5411
5412	=> imi 40100000 40200000
5413
5414	## Checking Image at 40100000 ...
5415	   Image Name:	 2.2.13 for initrd on TQM850L
5416	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5417	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5418	   Load Address: 00000000
5419	   Entry Point:	 0000000c
5420	   Verifying Checksum ... OK
5421
5422	## Checking Image at 40200000 ...
5423	   Image Name:	 Simple Ramdisk Image
5424	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5425	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5426	   Load Address: 00000000
5427	   Entry Point:	 00000000
5428	   Verifying Checksum ... OK
5429
5430	=> bootm 40100000 40200000
5431	## Booting Linux kernel at 40100000 ...
5432	   Image Name:	 2.2.13 for initrd on TQM850L
5433	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5434	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5435	   Load Address: 00000000
5436	   Entry Point:	 0000000c
5437	   Verifying Checksum ... OK
5438	   Uncompressing Kernel Image ... OK
5439	## Loading RAMDisk Image at 40200000 ...
5440	   Image Name:	 Simple Ramdisk Image
5441	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5442	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5443	   Load Address: 00000000
5444	   Entry Point:	 00000000
5445	   Verifying Checksum ... OK
5446	   Loading Ramdisk ... OK
5447	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
5448	Boot arguments: root=/dev/ram
5449	time_init: decrementer frequency = 187500000/60
5450	Calibrating delay loop... 49.77 BogoMIPS
5451	...
5452	RAMDISK: Compressed image found at block 0
5453	VFS: Mounted root (ext2 filesystem).
5454
5455	bash#
5456
5457Boot Linux and pass a flat device tree:
5458-----------
5459
5460First, U-Boot must be compiled with the appropriate defines. See the section
5461titled "Linux Kernel Interface" above for a more in depth explanation. The
5462following is an example of how to start a kernel and pass an updated
5463flat device tree:
5464
5465=> print oftaddr
5466oftaddr=0x300000
5467=> print oft
5468oft=oftrees/mpc8540ads.dtb
5469=> tftp $oftaddr $oft
5470Speed: 1000, full duplex
5471Using TSEC0 device
5472TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5473Filename 'oftrees/mpc8540ads.dtb'.
5474Load address: 0x300000
5475Loading: #
5476done
5477Bytes transferred = 4106 (100a hex)
5478=> tftp $loadaddr $bootfile
5479Speed: 1000, full duplex
5480Using TSEC0 device
5481TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5482Filename 'uImage'.
5483Load address: 0x200000
5484Loading:############
5485done
5486Bytes transferred = 1029407 (fb51f hex)
5487=> print loadaddr
5488loadaddr=200000
5489=> print oftaddr
5490oftaddr=0x300000
5491=> bootm $loadaddr - $oftaddr
5492## Booting image at 00200000 ...
5493   Image Name:	 Linux-2.6.17-dirty
5494   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5495   Data Size:	 1029343 Bytes = 1005.2 kB
5496   Load Address: 00000000
5497   Entry Point:	 00000000
5498   Verifying Checksum ... OK
5499   Uncompressing Kernel Image ... OK
5500Booting using flat device tree at 0x300000
5501Using MPC85xx ADS machine description
5502Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5503[snip]
5504
5505
5506More About U-Boot Image Types:
5507------------------------------
5508
5509U-Boot supports the following image types:
5510
5511   "Standalone Programs" are directly runnable in the environment
5512	provided by U-Boot; it is expected that (if they behave
5513	well) you can continue to work in U-Boot after return from
5514	the Standalone Program.
5515   "OS Kernel Images" are usually images of some Embedded OS which
5516	will take over control completely. Usually these programs
5517	will install their own set of exception handlers, device
5518	drivers, set up the MMU, etc. - this means, that you cannot
5519	expect to re-enter U-Boot except by resetting the CPU.
5520   "RAMDisk Images" are more or less just data blocks, and their
5521	parameters (address, size) are passed to an OS kernel that is
5522	being started.
5523   "Multi-File Images" contain several images, typically an OS
5524	(Linux) kernel image and one or more data images like
5525	RAMDisks. This construct is useful for instance when you want
5526	to boot over the network using BOOTP etc., where the boot
5527	server provides just a single image file, but you want to get
5528	for instance an OS kernel and a RAMDisk image.
5529
5530	"Multi-File Images" start with a list of image sizes, each
5531	image size (in bytes) specified by an "uint32_t" in network
5532	byte order. This list is terminated by an "(uint32_t)0".
5533	Immediately after the terminating 0 follow the images, one by
5534	one, all aligned on "uint32_t" boundaries (size rounded up to
5535	a multiple of 4 bytes).
5536
5537   "Firmware Images" are binary images containing firmware (like
5538	U-Boot or FPGA images) which usually will be programmed to
5539	flash memory.
5540
5541   "Script files" are command sequences that will be executed by
5542	U-Boot's command interpreter; this feature is especially
5543	useful when you configure U-Boot to use a real shell (hush)
5544	as command interpreter.
5545
5546Booting the Linux zImage:
5547-------------------------
5548
5549On some platforms, it's possible to boot Linux zImage. This is done
5550using the "bootz" command. The syntax of "bootz" command is the same
5551as the syntax of "bootm" command.
5552
5553Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5554kernel with raw initrd images. The syntax is slightly different, the
5555address of the initrd must be augmented by it's size, in the following
5556format: "<initrd addres>:<initrd size>".
5557
5558
5559Standalone HOWTO:
5560=================
5561
5562One of the features of U-Boot is that you can dynamically load and
5563run "standalone" applications, which can use some resources of
5564U-Boot like console I/O functions or interrupt services.
5565
5566Two simple examples are included with the sources:
5567
5568"Hello World" Demo:
5569-------------------
5570
5571'examples/hello_world.c' contains a small "Hello World" Demo
5572application; it is automatically compiled when you build U-Boot.
5573It's configured to run at address 0x00040004, so you can play with it
5574like that:
5575
5576	=> loads
5577	## Ready for S-Record download ...
5578	~>examples/hello_world.srec
5579	1 2 3 4 5 6 7 8 9 10 11 ...
5580	[file transfer complete]
5581	[connected]
5582	## Start Addr = 0x00040004
5583
5584	=> go 40004 Hello World! This is a test.
5585	## Starting application at 0x00040004 ...
5586	Hello World
5587	argc = 7
5588	argv[0] = "40004"
5589	argv[1] = "Hello"
5590	argv[2] = "World!"
5591	argv[3] = "This"
5592	argv[4] = "is"
5593	argv[5] = "a"
5594	argv[6] = "test."
5595	argv[7] = "<NULL>"
5596	Hit any key to exit ...
5597
5598	## Application terminated, rc = 0x0
5599
5600Another example, which demonstrates how to register a CPM interrupt
5601handler with the U-Boot code, can be found in 'examples/timer.c'.
5602Here, a CPM timer is set up to generate an interrupt every second.
5603The interrupt service routine is trivial, just printing a '.'
5604character, but this is just a demo program. The application can be
5605controlled by the following keys:
5606
5607	? - print current values og the CPM Timer registers
5608	b - enable interrupts and start timer
5609	e - stop timer and disable interrupts
5610	q - quit application
5611
5612	=> loads
5613	## Ready for S-Record download ...
5614	~>examples/timer.srec
5615	1 2 3 4 5 6 7 8 9 10 11 ...
5616	[file transfer complete]
5617	[connected]
5618	## Start Addr = 0x00040004
5619
5620	=> go 40004
5621	## Starting application at 0x00040004 ...
5622	TIMERS=0xfff00980
5623	Using timer 1
5624	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5625
5626Hit 'b':
5627	[q, b, e, ?] Set interval 1000000 us
5628	Enabling timer
5629Hit '?':
5630	[q, b, e, ?] ........
5631	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5632Hit '?':
5633	[q, b, e, ?] .
5634	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5635Hit '?':
5636	[q, b, e, ?] .
5637	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
5638Hit '?':
5639	[q, b, e, ?] .
5640	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
5641Hit 'e':
5642	[q, b, e, ?] ...Stopping timer
5643Hit 'q':
5644	[q, b, e, ?] ## Application terminated, rc = 0x0
5645
5646
5647Minicom warning:
5648================
5649
5650Over time, many people have reported problems when trying to use the
5651"minicom" terminal emulation program for serial download. I (wd)
5652consider minicom to be broken, and recommend not to use it. Under
5653Unix, I recommend to use C-Kermit for general purpose use (and
5654especially for kermit binary protocol download ("loadb" command), and
5655use "cu" for S-Record download ("loads" command).  See
5656http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
5657for help with kermit.
5658
5659
5660Nevertheless, if you absolutely want to use it try adding this
5661configuration to your "File transfer protocols" section:
5662
5663	   Name	   Program			Name U/D FullScr IO-Red. Multi
5664	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5665	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5666
5667
5668NetBSD Notes:
5669=============
5670
5671Starting at version 0.9.2, U-Boot supports NetBSD both as host
5672(build U-Boot) and target system (boots NetBSD/mpc8xx).
5673
5674Building requires a cross environment; it is known to work on
5675NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5676need gmake since the Makefiles are not compatible with BSD make).
5677Note that the cross-powerpc package does not install include files;
5678attempting to build U-Boot will fail because <machine/ansi.h> is
5679missing.  This file has to be installed and patched manually:
5680
5681	# cd /usr/pkg/cross/powerpc-netbsd/include
5682	# mkdir powerpc
5683	# ln -s powerpc machine
5684	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5685	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5686
5687Native builds *don't* work due to incompatibilities between native
5688and U-Boot include files.
5689
5690Booting assumes that (the first part of) the image booted is a
5691stage-2 loader which in turn loads and then invokes the kernel
5692proper. Loader sources will eventually appear in the NetBSD source
5693tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5694meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5695
5696
5697Implementation Internals:
5698=========================
5699
5700The following is not intended to be a complete description of every
5701implementation detail. However, it should help to understand the
5702inner workings of U-Boot and make it easier to port it to custom
5703hardware.
5704
5705
5706Initial Stack, Global Data:
5707---------------------------
5708
5709The implementation of U-Boot is complicated by the fact that U-Boot
5710starts running out of ROM (flash memory), usually without access to
5711system RAM (because the memory controller is not initialized yet).
5712This means that we don't have writable Data or BSS segments, and BSS
5713is not initialized as zero. To be able to get a C environment working
5714at all, we have to allocate at least a minimal stack. Implementation
5715options for this are defined and restricted by the CPU used: Some CPU
5716models provide on-chip memory (like the IMMR area on MPC8xx and
5717MPC826x processors), on others (parts of) the data cache can be
5718locked as (mis-) used as memory, etc.
5719
5720	Chris Hallinan posted a good summary of these issues to the
5721	U-Boot mailing list:
5722
5723	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
5724	From: "Chris Hallinan" <clh@net1plus.com>
5725	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
5726	...
5727
5728	Correct me if I'm wrong, folks, but the way I understand it
5729	is this: Using DCACHE as initial RAM for Stack, etc, does not
5730	require any physical RAM backing up the cache. The cleverness
5731	is that the cache is being used as a temporary supply of
5732	necessary storage before the SDRAM controller is setup. It's
5733	beyond the scope of this list to explain the details, but you
5734	can see how this works by studying the cache architecture and
5735	operation in the architecture and processor-specific manuals.
5736
5737	OCM is On Chip Memory, which I believe the 405GP has 4K. It
5738	is another option for the system designer to use as an
5739	initial stack/RAM area prior to SDRAM being available. Either
5740	option should work for you. Using CS 4 should be fine if your
5741	board designers haven't used it for something that would
5742	cause you grief during the initial boot! It is frequently not
5743	used.
5744
5745	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
5746	with your processor/board/system design. The default value
5747	you will find in any recent u-boot distribution in
5748	walnut.h should work for you. I'd set it to a value larger
5749	than your SDRAM module. If you have a 64MB SDRAM module, set
5750	it above 400_0000. Just make sure your board has no resources
5751	that are supposed to respond to that address! That code in
5752	start.S has been around a while and should work as is when
5753	you get the config right.
5754
5755	-Chris Hallinan
5756	DS4.COM, Inc.
5757
5758It is essential to remember this, since it has some impact on the C
5759code for the initialization procedures:
5760
5761* Initialized global data (data segment) is read-only. Do not attempt
5762  to write it.
5763
5764* Do not use any uninitialized global data (or implicitely initialized
5765  as zero data - BSS segment) at all - this is undefined, initiali-
5766  zation is performed later (when relocating to RAM).
5767
5768* Stack space is very limited. Avoid big data buffers or things like
5769  that.
5770
5771Having only the stack as writable memory limits means we cannot use
5772normal global data to share information beween the code. But it
5773turned out that the implementation of U-Boot can be greatly
5774simplified by making a global data structure (gd_t) available to all
5775functions. We could pass a pointer to this data as argument to _all_
5776functions, but this would bloat the code. Instead we use a feature of
5777the GCC compiler (Global Register Variables) to share the data: we
5778place a pointer (gd) to the global data into a register which we
5779reserve for this purpose.
5780
5781When choosing a register for such a purpose we are restricted by the
5782relevant  (E)ABI  specifications for the current architecture, and by
5783GCC's implementation.
5784
5785For PowerPC, the following registers have specific use:
5786	R1:	stack pointer
5787	R2:	reserved for system use
5788	R3-R4:	parameter passing and return values
5789	R5-R10: parameter passing
5790	R13:	small data area pointer
5791	R30:	GOT pointer
5792	R31:	frame pointer
5793
5794	(U-Boot also uses R12 as internal GOT pointer. r12
5795	is a volatile register so r12 needs to be reset when
5796	going back and forth between asm and C)
5797
5798    ==> U-Boot will use R2 to hold a pointer to the global data
5799
5800    Note: on PPC, we could use a static initializer (since the
5801    address of the global data structure is known at compile time),
5802    but it turned out that reserving a register results in somewhat
5803    smaller code - although the code savings are not that big (on
5804    average for all boards 752 bytes for the whole U-Boot image,
5805    624 text + 127 data).
5806
5807On Blackfin, the normal C ABI (except for P3) is followed as documented here:
5808	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
5809
5810    ==> U-Boot will use P3 to hold a pointer to the global data
5811
5812On ARM, the following registers are used:
5813
5814	R0:	function argument word/integer result
5815	R1-R3:	function argument word
5816	R9:	platform specific
5817	R10:	stack limit (used only if stack checking is enabled)
5818	R11:	argument (frame) pointer
5819	R12:	temporary workspace
5820	R13:	stack pointer
5821	R14:	link register
5822	R15:	program counter
5823
5824    ==> U-Boot will use R9 to hold a pointer to the global data
5825
5826    Note: on ARM, only R_ARM_RELATIVE relocations are supported.
5827
5828On Nios II, the ABI is documented here:
5829	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
5830
5831    ==> U-Boot will use gp to hold a pointer to the global data
5832
5833    Note: on Nios II, we give "-G0" option to gcc and don't use gp
5834    to access small data sections, so gp is free.
5835
5836On NDS32, the following registers are used:
5837
5838	R0-R1:	argument/return
5839	R2-R5:	argument
5840	R15:	temporary register for assembler
5841	R16:	trampoline register
5842	R28:	frame pointer (FP)
5843	R29:	global pointer (GP)
5844	R30:	link register (LP)
5845	R31:	stack pointer (SP)
5846	PC:	program counter (PC)
5847
5848    ==> U-Boot will use R10 to hold a pointer to the global data
5849
5850NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
5851or current versions of GCC may "optimize" the code too much.
5852
5853Memory Management:
5854------------------
5855
5856U-Boot runs in system state and uses physical addresses, i.e. the
5857MMU is not used either for address mapping nor for memory protection.
5858
5859The available memory is mapped to fixed addresses using the memory
5860controller. In this process, a contiguous block is formed for each
5861memory type (Flash, SDRAM, SRAM), even when it consists of several
5862physical memory banks.
5863
5864U-Boot is installed in the first 128 kB of the first Flash bank (on
5865TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
5866booting and sizing and initializing DRAM, the code relocates itself
5867to the upper end of DRAM. Immediately below the U-Boot code some
5868memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
5869configuration setting]. Below that, a structure with global Board
5870Info data is placed, followed by the stack (growing downward).
5871
5872Additionally, some exception handler code is copied to the low 8 kB
5873of DRAM (0x00000000 ... 0x00001FFF).
5874
5875So a typical memory configuration with 16 MB of DRAM could look like
5876this:
5877
5878	0x0000 0000	Exception Vector code
5879	      :
5880	0x0000 1FFF
5881	0x0000 2000	Free for Application Use
5882	      :
5883	      :
5884
5885	      :
5886	      :
5887	0x00FB FF20	Monitor Stack (Growing downward)
5888	0x00FB FFAC	Board Info Data and permanent copy of global data
5889	0x00FC 0000	Malloc Arena
5890	      :
5891	0x00FD FFFF
5892	0x00FE 0000	RAM Copy of Monitor Code
5893	...		eventually: LCD or video framebuffer
5894	...		eventually: pRAM (Protected RAM - unchanged by reset)
5895	0x00FF FFFF	[End of RAM]
5896
5897
5898System Initialization:
5899----------------------
5900
5901In the reset configuration, U-Boot starts at the reset entry point
5902(on most PowerPC systems at address 0x00000100). Because of the reset
5903configuration for CS0# this is a mirror of the onboard Flash memory.
5904To be able to re-map memory U-Boot then jumps to its link address.
5905To be able to implement the initialization code in C, a (small!)
5906initial stack is set up in the internal Dual Ported RAM (in case CPUs
5907which provide such a feature like MPC8xx or MPC8260), or in a locked
5908part of the data cache. After that, U-Boot initializes the CPU core,
5909the caches and the SIU.
5910
5911Next, all (potentially) available memory banks are mapped using a
5912preliminary mapping. For example, we put them on 512 MB boundaries
5913(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
5914on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
5915programmed for SDRAM access. Using the temporary configuration, a
5916simple memory test is run that determines the size of the SDRAM
5917banks.
5918
5919When there is more than one SDRAM bank, and the banks are of
5920different size, the largest is mapped first. For equal size, the first
5921bank (CS2#) is mapped first. The first mapping is always for address
59220x00000000, with any additional banks following immediately to create
5923contiguous memory starting from 0.
5924
5925Then, the monitor installs itself at the upper end of the SDRAM area
5926and allocates memory for use by malloc() and for the global Board
5927Info data; also, the exception vector code is copied to the low RAM
5928pages, and the final stack is set up.
5929
5930Only after this relocation will you have a "normal" C environment;
5931until that you are restricted in several ways, mostly because you are
5932running from ROM, and because the code will have to be relocated to a
5933new address in RAM.
5934
5935
5936U-Boot Porting Guide:
5937----------------------
5938
5939[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
5940list, October 2002]
5941
5942
5943int main(int argc, char *argv[])
5944{
5945	sighandler_t no_more_time;
5946
5947	signal(SIGALRM, no_more_time);
5948	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
5949
5950	if (available_money > available_manpower) {
5951		Pay consultant to port U-Boot;
5952		return 0;
5953	}
5954
5955	Download latest U-Boot source;
5956
5957	Subscribe to u-boot mailing list;
5958
5959	if (clueless)
5960		email("Hi, I am new to U-Boot, how do I get started?");
5961
5962	while (learning) {
5963		Read the README file in the top level directory;
5964		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
5965		Read applicable doc/*.README;
5966		Read the source, Luke;
5967		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
5968	}
5969
5970	if (available_money > toLocalCurrency ($2500))
5971		Buy a BDI3000;
5972	else
5973		Add a lot of aggravation and time;
5974
5975	if (a similar board exists) {	/* hopefully... */
5976		cp -a board/<similar> board/<myboard>
5977		cp include/configs/<similar>.h include/configs/<myboard>.h
5978	} else {
5979		Create your own board support subdirectory;
5980		Create your own board include/configs/<myboard>.h file;
5981	}
5982	Edit new board/<myboard> files
5983	Edit new include/configs/<myboard>.h
5984
5985	while (!accepted) {
5986		while (!running) {
5987			do {
5988				Add / modify source code;
5989			} until (compiles);
5990			Debug;
5991			if (clueless)
5992				email("Hi, I am having problems...");
5993		}
5994		Send patch file to the U-Boot email list;
5995		if (reasonable critiques)
5996			Incorporate improvements from email list code review;
5997		else
5998			Defend code as written;
5999	}
6000
6001	return 0;
6002}
6003
6004void no_more_time (int sig)
6005{
6006      hire_a_guru();
6007}
6008
6009
6010Coding Standards:
6011-----------------
6012
6013All contributions to U-Boot should conform to the Linux kernel
6014coding style; see the file "Documentation/CodingStyle" and the script
6015"scripts/Lindent" in your Linux kernel source directory.
6016
6017Source files originating from a different project (for example the
6018MTD subsystem) are generally exempt from these guidelines and are not
6019reformated to ease subsequent migration to newer versions of those
6020sources.
6021
6022Please note that U-Boot is implemented in C (and to some small parts in
6023Assembler); no C++ is used, so please do not use C++ style comments (//)
6024in your code.
6025
6026Please also stick to the following formatting rules:
6027- remove any trailing white space
6028- use TAB characters for indentation and vertical alignment, not spaces
6029- make sure NOT to use DOS '\r\n' line feeds
6030- do not add more than 2 consecutive empty lines to source files
6031- do not add trailing empty lines to source files
6032
6033Submissions which do not conform to the standards may be returned
6034with a request to reformat the changes.
6035
6036
6037Submitting Patches:
6038-------------------
6039
6040Since the number of patches for U-Boot is growing, we need to
6041establish some rules. Submissions which do not conform to these rules
6042may be rejected, even when they contain important and valuable stuff.
6043
6044Please see http://www.denx.de/wiki/U-Boot/Patches for details.
6045
6046Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
6047see http://lists.denx.de/mailman/listinfo/u-boot
6048
6049When you send a patch, please include the following information with
6050it:
6051
6052* For bug fixes: a description of the bug and how your patch fixes
6053  this bug. Please try to include a way of demonstrating that the
6054  patch actually fixes something.
6055
6056* For new features: a description of the feature and your
6057  implementation.
6058
6059* A CHANGELOG entry as plaintext (separate from the patch)
6060
6061* For major contributions, your entry to the CREDITS file
6062
6063* When you add support for a new board, don't forget to add a
6064  maintainer e-mail address to the boards.cfg file, too.
6065
6066* If your patch adds new configuration options, don't forget to
6067  document these in the README file.
6068
6069* The patch itself. If you are using git (which is *strongly*
6070  recommended) you can easily generate the patch using the
6071  "git format-patch". If you then use "git send-email" to send it to
6072  the U-Boot mailing list, you will avoid most of the common problems
6073  with some other mail clients.
6074
6075  If you cannot use git, use "diff -purN OLD NEW". If your version of
6076  diff does not support these options, then get the latest version of
6077  GNU diff.
6078
6079  The current directory when running this command shall be the parent
6080  directory of the U-Boot source tree (i. e. please make sure that
6081  your patch includes sufficient directory information for the
6082  affected files).
6083
6084  We prefer patches as plain text. MIME attachments are discouraged,
6085  and compressed attachments must not be used.
6086
6087* If one logical set of modifications affects or creates several
6088  files, all these changes shall be submitted in a SINGLE patch file.
6089
6090* Changesets that contain different, unrelated modifications shall be
6091  submitted as SEPARATE patches, one patch per changeset.
6092
6093
6094Notes:
6095
6096* Before sending the patch, run the MAKEALL script on your patched
6097  source tree and make sure that no errors or warnings are reported
6098  for any of the boards.
6099
6100* Keep your modifications to the necessary minimum: A patch
6101  containing several unrelated changes or arbitrary reformats will be
6102  returned with a request to re-formatting / split it.
6103
6104* If you modify existing code, make sure that your new code does not
6105  add to the memory footprint of the code ;-) Small is beautiful!
6106  When adding new features, these should compile conditionally only
6107  (using #ifdef), and the resulting code with the new feature
6108  disabled must not need more memory than the old code without your
6109  modification.
6110
6111* Remember that there is a size limit of 100 kB per message on the
6112  u-boot mailing list. Bigger patches will be moderated. If they are
6113  reasonable and not too big, they will be acknowledged. But patches
6114  bigger than the size limit should be avoided.
6115