xref: /rk3399_rockchip-uboot/README (revision 9ac4ffbde1a5015c9929ee8578d3811b716e2fd3)
1#
2# (C) Copyright 2000 - 2013
3# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
4#
5# SPDX-License-Identifier:	GPL-2.0+
6#
7
8Summary:
9========
10
11This directory contains the source code for U-Boot, a boot loader for
12Embedded boards based on PowerPC, ARM, MIPS and several other
13processors, which can be installed in a boot ROM and used to
14initialize and test the hardware or to download and run application
15code.
16
17The development of U-Boot is closely related to Linux: some parts of
18the source code originate in the Linux source tree, we have some
19header files in common, and special provision has been made to
20support booting of Linux images.
21
22Some attention has been paid to make this software easily
23configurable and extendable. For instance, all monitor commands are
24implemented with the same call interface, so that it's very easy to
25add new commands. Also, instead of permanently adding rarely used
26code (for instance hardware test utilities) to the monitor, you can
27load and run it dynamically.
28
29
30Status:
31=======
32
33In general, all boards for which a configuration option exists in the
34Makefile have been tested to some extent and can be considered
35"working". In fact, many of them are used in production systems.
36
37In case of problems see the CHANGELOG and CREDITS files to find out
38who contributed the specific port. The boards.cfg file lists board
39maintainers.
40
41Note: There is no CHANGELOG file in the actual U-Boot source tree;
42it can be created dynamically from the Git log using:
43
44	make CHANGELOG
45
46
47Where to get help:
48==================
49
50In case you have questions about, problems with or contributions for
51U-Boot you should send a message to the U-Boot mailing list at
52<u-boot@lists.denx.de>. There is also an archive of previous traffic
53on the mailing list - please search the archive before asking FAQ's.
54Please see http://lists.denx.de/pipermail/u-boot and
55http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
56
57
58Where to get source code:
59=========================
60
61The U-Boot source code is maintained in the git repository at
62git://www.denx.de/git/u-boot.git ; you can browse it online at
63http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
64
65The "snapshot" links on this page allow you to download tarballs of
66any version you might be interested in. Official releases are also
67available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
68directory.
69
70Pre-built (and tested) images are available from
71ftp://ftp.denx.de/pub/u-boot/images/
72
73
74Where we come from:
75===================
76
77- start from 8xxrom sources
78- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
79- clean up code
80- make it easier to add custom boards
81- make it possible to add other [PowerPC] CPUs
82- extend functions, especially:
83  * Provide extended interface to Linux boot loader
84  * S-Record download
85  * network boot
86  * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
87- create ARMBoot project (http://sourceforge.net/projects/armboot)
88- add other CPU families (starting with ARM)
89- create U-Boot project (http://sourceforge.net/projects/u-boot)
90- current project page: see http://www.denx.de/wiki/U-Boot
91
92
93Names and Spelling:
94===================
95
96The "official" name of this project is "Das U-Boot". The spelling
97"U-Boot" shall be used in all written text (documentation, comments
98in source files etc.). Example:
99
100	This is the README file for the U-Boot project.
101
102File names etc. shall be based on the string "u-boot". Examples:
103
104	include/asm-ppc/u-boot.h
105
106	#include <asm/u-boot.h>
107
108Variable names, preprocessor constants etc. shall be either based on
109the string "u_boot" or on "U_BOOT". Example:
110
111	U_BOOT_VERSION		u_boot_logo
112	IH_OS_U_BOOT		u_boot_hush_start
113
114
115Versioning:
116===========
117
118Starting with the release in October 2008, the names of the releases
119were changed from numerical release numbers without deeper meaning
120into a time stamp based numbering. Regular releases are identified by
121names consisting of the calendar year and month of the release date.
122Additional fields (if present) indicate release candidates or bug fix
123releases in "stable" maintenance trees.
124
125Examples:
126	U-Boot v2009.11	    - Release November 2009
127	U-Boot v2009.11.1   - Release 1 in version November 2009 stable tree
128	U-Boot v2010.09-rc1 - Release candiate 1 for September 2010 release
129
130
131Directory Hierarchy:
132====================
133
134/arch			Architecture specific files
135  /arm			Files generic to ARM architecture
136    /cpu		CPU specific files
137      /arm720t		Files specific to ARM 720 CPUs
138      /arm920t		Files specific to ARM 920 CPUs
139	/at91		Files specific to Atmel AT91RM9200 CPU
140	/imx		Files specific to Freescale MC9328 i.MX CPUs
141	/s3c24x0	Files specific to Samsung S3C24X0 CPUs
142      /arm926ejs	Files specific to ARM 926 CPUs
143      /arm1136		Files specific to ARM 1136 CPUs
144      /ixp		Files specific to Intel XScale IXP CPUs
145      /pxa		Files specific to Intel XScale PXA CPUs
146      /sa1100		Files specific to Intel StrongARM SA1100 CPUs
147    /lib		Architecture specific library files
148  /avr32		Files generic to AVR32 architecture
149    /cpu		CPU specific files
150    /lib		Architecture specific library files
151  /blackfin		Files generic to Analog Devices Blackfin architecture
152    /cpu		CPU specific files
153    /lib		Architecture specific library files
154  /m68k			Files generic to m68k architecture
155    /cpu		CPU specific files
156      /mcf52x2		Files specific to Freescale ColdFire MCF52x2 CPUs
157      /mcf5227x		Files specific to Freescale ColdFire MCF5227x CPUs
158      /mcf532x		Files specific to Freescale ColdFire MCF5329 CPUs
159      /mcf5445x		Files specific to Freescale ColdFire MCF5445x CPUs
160      /mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
161    /lib		Architecture specific library files
162  /microblaze		Files generic to microblaze architecture
163    /cpu		CPU specific files
164    /lib		Architecture specific library files
165  /mips			Files generic to MIPS architecture
166    /cpu		CPU specific files
167      /mips32		Files specific to MIPS32 CPUs
168      /xburst		Files specific to Ingenic XBurst CPUs
169    /lib		Architecture specific library files
170  /nds32		Files generic to NDS32 architecture
171    /cpu		CPU specific files
172      /n1213		Files specific to Andes Technology N1213 CPUs
173    /lib		Architecture specific library files
174  /nios2		Files generic to Altera NIOS2 architecture
175    /cpu		CPU specific files
176    /lib		Architecture specific library files
177  /openrisc		Files generic to OpenRISC architecture
178    /cpu		CPU specific files
179    /lib		Architecture specific library files
180  /powerpc		Files generic to PowerPC architecture
181    /cpu		CPU specific files
182      /74xx_7xx		Files specific to Freescale MPC74xx and 7xx CPUs
183      /mpc5xx		Files specific to Freescale MPC5xx CPUs
184      /mpc5xxx		Files specific to Freescale MPC5xxx CPUs
185      /mpc8xx		Files specific to Freescale MPC8xx CPUs
186      /mpc824x		Files specific to Freescale MPC824x CPUs
187      /mpc8260		Files specific to Freescale MPC8260 CPUs
188      /mpc85xx		Files specific to Freescale MPC85xx CPUs
189      /ppc4xx		Files specific to AMCC PowerPC 4xx CPUs
190    /lib		Architecture specific library files
191  /sh			Files generic to SH architecture
192    /cpu		CPU specific files
193      /sh2		Files specific to sh2 CPUs
194      /sh3		Files specific to sh3 CPUs
195      /sh4		Files specific to sh4 CPUs
196    /lib		Architecture specific library files
197  /sparc		Files generic to SPARC architecture
198    /cpu		CPU specific files
199      /leon2		Files specific to Gaisler LEON2 SPARC CPU
200      /leon3		Files specific to Gaisler LEON3 SPARC CPU
201    /lib		Architecture specific library files
202  /x86			Files generic to x86 architecture
203    /cpu		CPU specific files
204    /lib		Architecture specific library files
205/api			Machine/arch independent API for external apps
206/board			Board dependent files
207/common			Misc architecture independent functions
208/disk			Code for disk drive partition handling
209/doc			Documentation (don't expect too much)
210/drivers		Commonly used device drivers
211/dts			Contains Makefile for building internal U-Boot fdt.
212/examples		Example code for standalone applications, etc.
213/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
214/include		Header Files
215/lib			Files generic to all architectures
216  /libfdt		Library files to support flattened device trees
217  /lzma			Library files to support LZMA decompression
218  /lzo			Library files to support LZO decompression
219/net			Networking code
220/post			Power On Self Test
221/spl			Secondary Program Loader framework
222/tools			Tools to build S-Record or U-Boot images, etc.
223
224Software Configuration:
225=======================
226
227Configuration is usually done using C preprocessor defines; the
228rationale behind that is to avoid dead code whenever possible.
229
230There are two classes of configuration variables:
231
232* Configuration _OPTIONS_:
233  These are selectable by the user and have names beginning with
234  "CONFIG_".
235
236* Configuration _SETTINGS_:
237  These depend on the hardware etc. and should not be meddled with if
238  you don't know what you're doing; they have names beginning with
239  "CONFIG_SYS_".
240
241Later we will add a configuration tool - probably similar to or even
242identical to what's used for the Linux kernel. Right now, we have to
243do the configuration by hand, which means creating some symbolic
244links and editing some configuration files. We use the TQM8xxL boards
245as an example here.
246
247
248Selection of Processor Architecture and Board Type:
249---------------------------------------------------
250
251For all supported boards there are ready-to-use default
252configurations available; just type "make <board_name>_config".
253
254Example: For a TQM823L module type:
255
256	cd u-boot
257	make TQM823L_config
258
259For the Cogent platform, you need to specify the CPU type as well;
260e.g. "make cogent_mpc8xx_config". And also configure the cogent
261directory according to the instructions in cogent/README.
262
263
264Configuration Options:
265----------------------
266
267Configuration depends on the combination of board and CPU type; all
268such information is kept in a configuration file
269"include/configs/<board_name>.h".
270
271Example: For a TQM823L module, all configuration settings are in
272"include/configs/TQM823L.h".
273
274
275Many of the options are named exactly as the corresponding Linux
276kernel configuration options. The intention is to make it easier to
277build a config tool - later.
278
279
280The following options need to be configured:
281
282- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
283
284- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
285
286- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
287		Define exactly one, e.g. CONFIG_ATSTK1002
288
289- CPU Module Type: (if CONFIG_COGENT is defined)
290		Define exactly one of
291		CONFIG_CMA286_60_OLD
292--- FIXME --- not tested yet:
293		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
294		CONFIG_CMA287_23, CONFIG_CMA287_50
295
296- Motherboard Type: (if CONFIG_COGENT is defined)
297		Define exactly one of
298		CONFIG_CMA101, CONFIG_CMA102
299
300- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
301		Define one or more of
302		CONFIG_CMA302
303
304- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
305		Define one or more of
306		CONFIG_LCD_HEARTBEAT	- update a character position on
307					  the LCD display every second with
308					  a "rotator" |\-/|\-/
309
310- Board flavour: (if CONFIG_MPC8260ADS is defined)
311		CONFIG_ADSTYPE
312		Possible values are:
313			CONFIG_SYS_8260ADS	- original MPC8260ADS
314			CONFIG_SYS_8266ADS	- MPC8266ADS
315			CONFIG_SYS_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
316			CONFIG_SYS_8272ADS	- MPC8272ADS
317
318- Marvell Family Member
319		CONFIG_SYS_MVFS		- define it if you want to enable
320					  multiple fs option at one time
321					  for marvell soc family
322
323- MPC824X Family Member (if CONFIG_MPC824X is defined)
324		Define exactly one of
325		CONFIG_MPC8240, CONFIG_MPC8245
326
327- 8xx CPU Options: (if using an MPC8xx CPU)
328		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
329					  get_gclk_freq() cannot work
330					  e.g. if there is no 32KHz
331					  reference PIT/RTC clock
332		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
333					  or XTAL/EXTAL)
334
335- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
336		CONFIG_SYS_8xx_CPUCLK_MIN
337		CONFIG_SYS_8xx_CPUCLK_MAX
338		CONFIG_8xx_CPUCLK_DEFAULT
339			See doc/README.MPC866
340
341		CONFIG_SYS_MEASURE_CPUCLK
342
343		Define this to measure the actual CPU clock instead
344		of relying on the correctness of the configured
345		values. Mostly useful for board bringup to make sure
346		the PLL is locked at the intended frequency. Note
347		that this requires a (stable) reference clock (32 kHz
348		RTC clock or CONFIG_SYS_8XX_XIN)
349
350		CONFIG_SYS_DELAYED_ICACHE
351
352		Define this option if you want to enable the
353		ICache only when Code runs from RAM.
354
355- 85xx CPU Options:
356		CONFIG_SYS_PPC64
357
358		Specifies that the core is a 64-bit PowerPC implementation (implements
359		the "64" category of the Power ISA). This is necessary for ePAPR
360		compliance, among other possible reasons.
361
362		CONFIG_SYS_FSL_TBCLK_DIV
363
364		Defines the core time base clock divider ratio compared to the
365		system clock.  On most PQ3 devices this is 8, on newer QorIQ
366		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
367
368		CONFIG_SYS_FSL_PCIE_COMPAT
369
370		Defines the string to utilize when trying to match PCIe device
371		tree nodes for the given platform.
372
373		CONFIG_SYS_PPC_E500_DEBUG_TLB
374
375		Enables a temporary TLB entry to be used during boot to work
376		around limitations in e500v1 and e500v2 external debugger
377		support. This reduces the portions of the boot code where
378		breakpoints and single stepping do not work.  The value of this
379		symbol should be set to the TLB1 entry to be used for this
380		purpose.
381
382		CONFIG_SYS_FSL_ERRATUM_A004510
383
384		Enables a workaround for erratum A004510.  If set,
385		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
386		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
387
388		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
389		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
390
391		Defines one or two SoC revisions (low 8 bits of SVR)
392		for which the A004510 workaround should be applied.
393
394		The rest of SVR is either not relevant to the decision
395		of whether the erratum is present (e.g. p2040 versus
396		p2041) or is implied by the build target, which controls
397		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
398
399		See Freescale App Note 4493 for more information about
400		this erratum.
401
402		CONFIG_A003399_NOR_WORKAROUND
403		Enables a workaround for IFC erratum A003399. It is only
404		requred during NOR boot.
405
406		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
407
408		This is the value to write into CCSR offset 0x18600
409		according to the A004510 workaround.
410
411		CONFIG_SYS_FSL_DSP_DDR_ADDR
412		This value denotes start offset of DDR memory which is
413		connected exclusively to the DSP cores.
414
415		CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
416		This value denotes start offset of M2 memory
417		which is directly connected to the DSP core.
418
419		CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
420		This value denotes start offset of M3 memory which is directly
421		connected to the DSP core.
422
423		CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
424		This value denotes start offset of DSP CCSR space.
425
426- Generic CPU options:
427		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
428
429		Defines the endianess of the CPU. Implementation of those
430		values is arch specific.
431
432		CONFIG_SYS_FSL_DDR
433		Freescale DDR driver in use. This type of DDR controller is
434		found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
435		SoCs.
436
437		CONFIG_SYS_FSL_DDR_ADDR
438		Freescale DDR memory-mapped register base.
439
440		CONFIG_SYS_FSL_DDR_EMU
441		Specify emulator support for DDR. Some DDR features such as
442		deskew training are not available.
443
444		CONFIG_SYS_FSL_DDRC_GEN1
445		Freescale DDR1 controller.
446
447		CONFIG_SYS_FSL_DDRC_GEN2
448		Freescale DDR2 controller.
449
450		CONFIG_SYS_FSL_DDRC_GEN3
451		Freescale DDR3 controller.
452
453		CONFIG_SYS_FSL_DDRC_ARM_GEN3
454		Freescale DDR3 controller for ARM-based SoCs.
455
456		CONFIG_SYS_FSL_DDR1
457		Board config to use DDR1. It can be enabled for SoCs with
458		Freescale DDR1 or DDR2 controllers, depending on the board
459		implemetation.
460
461		CONFIG_SYS_FSL_DDR2
462		Board config to use DDR2. It can be eanbeld for SoCs with
463		Freescale DDR2 or DDR3 controllers, depending on the board
464		implementation.
465
466		CONFIG_SYS_FSL_DDR3
467		Board config to use DDR3. It can be enabled for SoCs with
468		Freescale DDR3 controllers.
469
470- Intel Monahans options:
471		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
472
473		Defines the Monahans run mode to oscillator
474		ratio. Valid values are 8, 16, 24, 31. The core
475		frequency is this value multiplied by 13 MHz.
476
477		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
478
479		Defines the Monahans turbo mode to oscillator
480		ratio. Valid values are 1 (default if undefined) and
481		2. The core frequency as calculated above is multiplied
482		by this value.
483
484- MIPS CPU options:
485		CONFIG_SYS_INIT_SP_OFFSET
486
487		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
488		pointer. This is needed for the temporary stack before
489		relocation.
490
491		CONFIG_SYS_MIPS_CACHE_MODE
492
493		Cache operation mode for the MIPS CPU.
494		See also arch/mips/include/asm/mipsregs.h.
495		Possible values are:
496			CONF_CM_CACHABLE_NO_WA
497			CONF_CM_CACHABLE_WA
498			CONF_CM_UNCACHED
499			CONF_CM_CACHABLE_NONCOHERENT
500			CONF_CM_CACHABLE_CE
501			CONF_CM_CACHABLE_COW
502			CONF_CM_CACHABLE_CUW
503			CONF_CM_CACHABLE_ACCELERATED
504
505		CONFIG_SYS_XWAY_EBU_BOOTCFG
506
507		Special option for Lantiq XWAY SoCs for booting from NOR flash.
508		See also arch/mips/cpu/mips32/start.S.
509
510		CONFIG_XWAY_SWAP_BYTES
511
512		Enable compilation of tools/xway-swap-bytes needed for Lantiq
513		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
514		be swapped if a flash programmer is used.
515
516- ARM options:
517		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
518
519		Select high exception vectors of the ARM core, e.g., do not
520		clear the V bit of the c1 register of CP15.
521
522		CONFIG_SYS_THUMB_BUILD
523
524		Use this flag to build U-Boot using the Thumb instruction
525		set for ARM architectures. Thumb instruction set provides
526		better code density. For ARM architectures that support
527		Thumb2 this flag will result in Thumb2 code generated by
528		GCC.
529
530		CONFIG_ARM_ERRATA_716044
531		CONFIG_ARM_ERRATA_742230
532		CONFIG_ARM_ERRATA_743622
533		CONFIG_ARM_ERRATA_751472
534
535		If set, the workarounds for these ARM errata are applied early
536		during U-Boot startup. Note that these options force the
537		workarounds to be applied; no CPU-type/version detection
538		exists, unlike the similar options in the Linux kernel. Do not
539		set these options unless they apply!
540
541- CPU timer options:
542		CONFIG_SYS_HZ
543
544		The frequency of the timer returned by get_timer().
545		get_timer() must operate in milliseconds and this CONFIG
546		option must be set to 1000.
547
548- Linux Kernel Interface:
549		CONFIG_CLOCKS_IN_MHZ
550
551		U-Boot stores all clock information in Hz
552		internally. For binary compatibility with older Linux
553		kernels (which expect the clocks passed in the
554		bd_info data to be in MHz) the environment variable
555		"clocks_in_mhz" can be defined so that U-Boot
556		converts clock data to MHZ before passing it to the
557		Linux kernel.
558		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
559		"clocks_in_mhz=1" is automatically included in the
560		default environment.
561
562		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
563
564		When transferring memsize parameter to linux, some versions
565		expect it to be in bytes, others in MB.
566		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
567
568		CONFIG_OF_LIBFDT
569
570		New kernel versions are expecting firmware settings to be
571		passed using flattened device trees (based on open firmware
572		concepts).
573
574		CONFIG_OF_LIBFDT
575		 * New libfdt-based support
576		 * Adds the "fdt" command
577		 * The bootm command automatically updates the fdt
578
579		OF_CPU - The proper name of the cpus node (only required for
580			MPC512X and MPC5xxx based boards).
581		OF_SOC - The proper name of the soc node (only required for
582			MPC512X and MPC5xxx based boards).
583		OF_TBCLK - The timebase frequency.
584		OF_STDOUT_PATH - The path to the console device
585
586		boards with QUICC Engines require OF_QE to set UCC MAC
587		addresses
588
589		CONFIG_OF_BOARD_SETUP
590
591		Board code has addition modification that it wants to make
592		to the flat device tree before handing it off to the kernel
593
594		CONFIG_OF_BOOT_CPU
595
596		This define fills in the correct boot CPU in the boot
597		param header, the default value is zero if undefined.
598
599		CONFIG_OF_IDE_FIXUP
600
601		U-Boot can detect if an IDE device is present or not.
602		If not, and this new config option is activated, U-Boot
603		removes the ATA node from the DTS before booting Linux,
604		so the Linux IDE driver does not probe the device and
605		crash. This is needed for buggy hardware (uc101) where
606		no pull down resistor is connected to the signal IDE5V_DD7.
607
608		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
609
610		This setting is mandatory for all boards that have only one
611		machine type and must be used to specify the machine type
612		number as it appears in the ARM machine registry
613		(see http://www.arm.linux.org.uk/developer/machines/).
614		Only boards that have multiple machine types supported
615		in a single configuration file and the machine type is
616		runtime discoverable, do not have to use this setting.
617
618- vxWorks boot parameters:
619
620		bootvx constructs a valid bootline using the following
621		environments variables: bootfile, ipaddr, serverip, hostname.
622		It loads the vxWorks image pointed bootfile.
623
624		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
625		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
626		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
627		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
628
629		CONFIG_SYS_VXWORKS_ADD_PARAMS
630
631		Add it at the end of the bootline. E.g "u=username pw=secret"
632
633		Note: If a "bootargs" environment is defined, it will overwride
634		the defaults discussed just above.
635
636- Cache Configuration:
637		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
638		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
639		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
640
641- Cache Configuration for ARM:
642		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
643				      controller
644		CONFIG_SYS_PL310_BASE - Physical base address of PL310
645					controller register space
646
647- Serial Ports:
648		CONFIG_PL010_SERIAL
649
650		Define this if you want support for Amba PrimeCell PL010 UARTs.
651
652		CONFIG_PL011_SERIAL
653
654		Define this if you want support for Amba PrimeCell PL011 UARTs.
655
656		CONFIG_PL011_CLOCK
657
658		If you have Amba PrimeCell PL011 UARTs, set this variable to
659		the clock speed of the UARTs.
660
661		CONFIG_PL01x_PORTS
662
663		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
664		define this to a list of base addresses for each (supported)
665		port. See e.g. include/configs/versatile.h
666
667		CONFIG_PL011_SERIAL_RLCR
668
669		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
670		have separate receive and transmit line control registers.  Set
671		this variable to initialize the extra register.
672
673		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
674
675		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
676		boot loader that has already initialized the UART.  Define this
677		variable to flush the UART at init time.
678
679
680- Console Interface:
681		Depending on board, define exactly one serial port
682		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
683		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
684		console by defining CONFIG_8xx_CONS_NONE
685
686		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
687		port routines must be defined elsewhere
688		(i.e. serial_init(), serial_getc(), ...)
689
690		CONFIG_CFB_CONSOLE
691		Enables console device for a color framebuffer. Needs following
692		defines (cf. smiLynxEM, i8042)
693			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
694						(default big endian)
695			VIDEO_HW_RECTFILL	graphic chip supports
696						rectangle fill
697						(cf. smiLynxEM)
698			VIDEO_HW_BITBLT		graphic chip supports
699						bit-blit (cf. smiLynxEM)
700			VIDEO_VISIBLE_COLS	visible pixel columns
701						(cols=pitch)
702			VIDEO_VISIBLE_ROWS	visible pixel rows
703			VIDEO_PIXEL_SIZE	bytes per pixel
704			VIDEO_DATA_FORMAT	graphic data format
705						(0-5, cf. cfb_console.c)
706			VIDEO_FB_ADRS		framebuffer address
707			VIDEO_KBD_INIT_FCT	keyboard int fct
708						(i.e. i8042_kbd_init())
709			VIDEO_TSTC_FCT		test char fct
710						(i.e. i8042_tstc)
711			VIDEO_GETC_FCT		get char fct
712						(i.e. i8042_getc)
713			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
714						(requires blink timer
715						cf. i8042.c)
716			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
717			CONFIG_CONSOLE_TIME	display time/date info in
718						upper right corner
719						(requires CONFIG_CMD_DATE)
720			CONFIG_VIDEO_LOGO	display Linux logo in
721						upper left corner
722			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
723						linux_logo.h for logo.
724						Requires CONFIG_VIDEO_LOGO
725			CONFIG_CONSOLE_EXTRA_INFO
726						additional board info beside
727						the logo
728
729		When CONFIG_CFB_CONSOLE_ANSI is defined, console will support
730		a limited number of ANSI escape sequences (cursor control,
731		erase functions and limited graphics rendition control).
732
733		When CONFIG_CFB_CONSOLE is defined, video console is
734		default i/o. Serial console can be forced with
735		environment 'console=serial'.
736
737		When CONFIG_SILENT_CONSOLE is defined, all console
738		messages (by U-Boot and Linux!) can be silenced with
739		the "silent" environment variable. See
740		doc/README.silent for more information.
741
742		CONFIG_SYS_CONSOLE_BG_COL: define the backgroundcolor, default
743			is 0x00.
744		CONFIG_SYS_CONSOLE_FG_COL: define the foregroundcolor, default
745			is 0xa0.
746
747- Console Baudrate:
748		CONFIG_BAUDRATE - in bps
749		Select one of the baudrates listed in
750		CONFIG_SYS_BAUDRATE_TABLE, see below.
751		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
752
753- Console Rx buffer length
754		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
755		the maximum receive buffer length for the SMC.
756		This option is actual only for 82xx and 8xx possible.
757		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
758		must be defined, to setup the maximum idle timeout for
759		the SMC.
760
761- Pre-Console Buffer:
762		Prior to the console being initialised (i.e. serial UART
763		initialised etc) all console output is silently discarded.
764		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
765		buffer any console messages prior to the console being
766		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
767		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
768		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
769		bytes are output before the console is initialised, the
770		earlier bytes are discarded.
771
772		'Sane' compilers will generate smaller code if
773		CONFIG_PRE_CON_BUF_SZ is a power of 2
774
775- Safe printf() functions
776		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
777		the printf() functions. These are defined in
778		include/vsprintf.h and include snprintf(), vsnprintf() and
779		so on. Code size increase is approximately 300-500 bytes.
780		If this option is not given then these functions will
781		silently discard their buffer size argument - this means
782		you are not getting any overflow checking in this case.
783
784- Boot Delay:	CONFIG_BOOTDELAY - in seconds
785		Delay before automatically booting the default image;
786		set to -1 to disable autoboot.
787		set to -2 to autoboot with no delay and not check for abort
788		(even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).
789
790		See doc/README.autoboot for these options that
791		work with CONFIG_BOOTDELAY. None are required.
792		CONFIG_BOOT_RETRY_TIME
793		CONFIG_BOOT_RETRY_MIN
794		CONFIG_AUTOBOOT_KEYED
795		CONFIG_AUTOBOOT_PROMPT
796		CONFIG_AUTOBOOT_DELAY_STR
797		CONFIG_AUTOBOOT_STOP_STR
798		CONFIG_AUTOBOOT_DELAY_STR2
799		CONFIG_AUTOBOOT_STOP_STR2
800		CONFIG_ZERO_BOOTDELAY_CHECK
801		CONFIG_RESET_TO_RETRY
802
803- Autoboot Command:
804		CONFIG_BOOTCOMMAND
805		Only needed when CONFIG_BOOTDELAY is enabled;
806		define a command string that is automatically executed
807		when no character is read on the console interface
808		within "Boot Delay" after reset.
809
810		CONFIG_BOOTARGS
811		This can be used to pass arguments to the bootm
812		command. The value of CONFIG_BOOTARGS goes into the
813		environment value "bootargs".
814
815		CONFIG_RAMBOOT and CONFIG_NFSBOOT
816		The value of these goes into the environment as
817		"ramboot" and "nfsboot" respectively, and can be used
818		as a convenience, when switching between booting from
819		RAM and NFS.
820
821- Pre-Boot Commands:
822		CONFIG_PREBOOT
823
824		When this option is #defined, the existence of the
825		environment variable "preboot" will be checked
826		immediately before starting the CONFIG_BOOTDELAY
827		countdown and/or running the auto-boot command resp.
828		entering interactive mode.
829
830		This feature is especially useful when "preboot" is
831		automatically generated or modified. For an example
832		see the LWMON board specific code: here "preboot" is
833		modified when the user holds down a certain
834		combination of keys on the (special) keyboard when
835		booting the systems
836
837- Serial Download Echo Mode:
838		CONFIG_LOADS_ECHO
839		If defined to 1, all characters received during a
840		serial download (using the "loads" command) are
841		echoed back. This might be needed by some terminal
842		emulations (like "cu"), but may as well just take
843		time on others. This setting #define's the initial
844		value of the "loads_echo" environment variable.
845
846- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
847		CONFIG_KGDB_BAUDRATE
848		Select one of the baudrates listed in
849		CONFIG_SYS_BAUDRATE_TABLE, see below.
850
851- Monitor Functions:
852		Monitor commands can be included or excluded
853		from the build by using the #include files
854		<config_cmd_all.h> and #undef'ing unwanted
855		commands, or using <config_cmd_default.h>
856		and augmenting with additional #define's
857		for wanted commands.
858
859		The default command configuration includes all commands
860		except those marked below with a "*".
861
862		CONFIG_CMD_ASKENV	* ask for env variable
863		CONFIG_CMD_BDI		  bdinfo
864		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
865		CONFIG_CMD_BMP		* BMP support
866		CONFIG_CMD_BSP		* Board specific commands
867		CONFIG_CMD_BOOTD	  bootd
868		CONFIG_CMD_CACHE	* icache, dcache
869		CONFIG_CMD_CONSOLE	  coninfo
870		CONFIG_CMD_CRC32	* crc32
871		CONFIG_CMD_DATE		* support for RTC, date/time...
872		CONFIG_CMD_DHCP		* DHCP support
873		CONFIG_CMD_DIAG		* Diagnostics
874		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
875		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
876		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
877		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
878		CONFIG_CMD_DTT		* Digital Therm and Thermostat
879		CONFIG_CMD_ECHO		  echo arguments
880		CONFIG_CMD_EDITENV	  edit env variable
881		CONFIG_CMD_EEPROM	* EEPROM read/write support
882		CONFIG_CMD_ELF		* bootelf, bootvx
883		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
884		CONFIG_CMD_ENV_FLAGS	* display details about env flags
885		CONFIG_CMD_ENV_EXISTS	* check existence of env variable
886		CONFIG_CMD_EXPORTENV	* export the environment
887		CONFIG_CMD_EXT2		* ext2 command support
888		CONFIG_CMD_EXT4		* ext4 command support
889		CONFIG_CMD_SAVEENV	  saveenv
890		CONFIG_CMD_FDC		* Floppy Disk Support
891		CONFIG_CMD_FAT		* FAT command support
892		CONFIG_CMD_FDOS		* Dos diskette Support
893		CONFIG_CMD_FLASH	  flinfo, erase, protect
894		CONFIG_CMD_FPGA		  FPGA device initialization support
895		CONFIG_CMD_FUSE		* Device fuse support
896		CONFIG_CMD_GETTIME	* Get time since boot
897		CONFIG_CMD_GO		* the 'go' command (exec code)
898		CONFIG_CMD_GREPENV	* search environment
899		CONFIG_CMD_HASH		* calculate hash / digest
900		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
901		CONFIG_CMD_I2C		* I2C serial bus support
902		CONFIG_CMD_IDE		* IDE harddisk support
903		CONFIG_CMD_IMI		  iminfo
904		CONFIG_CMD_IMLS		  List all images found in NOR flash
905		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash
906		CONFIG_CMD_IMMAP	* IMMR dump support
907		CONFIG_CMD_IMPORTENV	* import an environment
908		CONFIG_CMD_INI		* import data from an ini file into the env
909		CONFIG_CMD_IRQ		* irqinfo
910		CONFIG_CMD_ITEST	  Integer/string test of 2 values
911		CONFIG_CMD_JFFS2	* JFFS2 Support
912		CONFIG_CMD_KGDB		* kgdb
913		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)
914		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
915					  (169.254.*.*)
916		CONFIG_CMD_LOADB	  loadb
917		CONFIG_CMD_LOADS	  loads
918		CONFIG_CMD_MD5SUM	* print md5 message digest
919					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
920		CONFIG_CMD_MEMINFO	* Display detailed memory information
921		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
922					  loop, loopw
923		CONFIG_CMD_MEMTEST	* mtest
924		CONFIG_CMD_MISC		  Misc functions like sleep etc
925		CONFIG_CMD_MMC		* MMC memory mapped support
926		CONFIG_CMD_MII		* MII utility commands
927		CONFIG_CMD_MTDPARTS	* MTD partition support
928		CONFIG_CMD_NAND		* NAND support
929		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
930		CONFIG_CMD_NFS		  NFS support
931		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
932		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
933		CONFIG_CMD_PCI		* pciinfo
934		CONFIG_CMD_PCMCIA		* PCMCIA support
935		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
936					  host
937		CONFIG_CMD_PORTIO	* Port I/O
938		CONFIG_CMD_READ		* Read raw data from partition
939		CONFIG_CMD_REGINFO	* Register dump
940		CONFIG_CMD_RUN		  run command in env variable
941		CONFIG_CMD_SANDBOX	* sb command to access sandbox features
942		CONFIG_CMD_SAVES	* save S record dump
943		CONFIG_CMD_SCSI		* SCSI Support
944		CONFIG_CMD_SDRAM	* print SDRAM configuration information
945					  (requires CONFIG_CMD_I2C)
946		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
947					  (4xx only)
948		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
949		CONFIG_CMD_SHA1SUM	* print sha1 memory digest
950					  (requires CONFIG_CMD_MEMORY)
951		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x
952		CONFIG_CMD_SOURCE	  "source" command Support
953		CONFIG_CMD_SPI		* SPI serial bus support
954		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
955		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
956		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
957		CONFIG_CMD_TIMER	* access to the system tick timer
958		CONFIG_CMD_USB		* USB support
959		CONFIG_CMD_CDP		* Cisco Discover Protocol support
960		CONFIG_CMD_MFSL		* Microblaze FSL support
961		CONFIG_CMD_XIMG		  Load part of Multi Image
962
963
964		EXAMPLE: If you want all functions except of network
965		support you can write:
966
967		#include "config_cmd_all.h"
968		#undef CONFIG_CMD_NET
969
970	Other Commands:
971		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
972
973	Note:	Don't enable the "icache" and "dcache" commands
974		(configuration option CONFIG_CMD_CACHE) unless you know
975		what you (and your U-Boot users) are doing. Data
976		cache cannot be enabled on systems like the 8xx or
977		8260 (where accesses to the IMMR region must be
978		uncached), and it cannot be disabled on all other
979		systems where we (mis-) use the data cache to hold an
980		initial stack and some data.
981
982
983		XXX - this list needs to get updated!
984
985- Regular expression support:
986		CONFIG_REGEX
987		If this variable is defined, U-Boot is linked against
988		the SLRE (Super Light Regular Expression) library,
989		which adds regex support to some commands, as for
990		example "env grep" and "setexpr".
991
992- Device tree:
993		CONFIG_OF_CONTROL
994		If this variable is defined, U-Boot will use a device tree
995		to configure its devices, instead of relying on statically
996		compiled #defines in the board file. This option is
997		experimental and only available on a few boards. The device
998		tree is available in the global data as gd->fdt_blob.
999
1000		U-Boot needs to get its device tree from somewhere. This can
1001		be done using one of the two options below:
1002
1003		CONFIG_OF_EMBED
1004		If this variable is defined, U-Boot will embed a device tree
1005		binary in its image. This device tree file should be in the
1006		board directory and called <soc>-<board>.dts. The binary file
1007		is then picked up in board_init_f() and made available through
1008		the global data structure as gd->blob.
1009
1010		CONFIG_OF_SEPARATE
1011		If this variable is defined, U-Boot will build a device tree
1012		binary. It will be called u-boot.dtb. Architecture-specific
1013		code will locate it at run-time. Generally this works by:
1014
1015			cat u-boot.bin u-boot.dtb >image.bin
1016
1017		and in fact, U-Boot does this for you, creating a file called
1018		u-boot-dtb.bin which is useful in the common case. You can
1019		still use the individual files if you need something more
1020		exotic.
1021
1022- Watchdog:
1023		CONFIG_WATCHDOG
1024		If this variable is defined, it enables watchdog
1025		support for the SoC. There must be support in the SoC
1026		specific code for a watchdog. For the 8xx and 8260
1027		CPUs, the SIU Watchdog feature is enabled in the SYPCR
1028		register.  When supported for a specific SoC is
1029		available, then no further board specific code should
1030		be needed to use it.
1031
1032		CONFIG_HW_WATCHDOG
1033		When using a watchdog circuitry external to the used
1034		SoC, then define this variable and provide board
1035		specific code for the "hw_watchdog_reset" function.
1036
1037- U-Boot Version:
1038		CONFIG_VERSION_VARIABLE
1039		If this variable is defined, an environment variable
1040		named "ver" is created by U-Boot showing the U-Boot
1041		version as printed by the "version" command.
1042		Any change to this variable will be reverted at the
1043		next reset.
1044
1045- Real-Time Clock:
1046
1047		When CONFIG_CMD_DATE is selected, the type of the RTC
1048		has to be selected, too. Define exactly one of the
1049		following options:
1050
1051		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
1052		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
1053		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
1054		CONFIG_RTC_MC146818	- use MC146818 RTC
1055		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
1056		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
1057		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
1058		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
1059		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
1060		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
1061		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
1062		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
1063					  RV3029 RTC.
1064
1065		Note that if the RTC uses I2C, then the I2C interface
1066		must also be configured. See I2C Support, below.
1067
1068- GPIO Support:
1069		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
1070
1071		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1072		chip-ngpio pairs that tell the PCA953X driver the number of
1073		pins supported by a particular chip.
1074
1075		Note that if the GPIO device uses I2C, then the I2C interface
1076		must also be configured. See I2C Support, below.
1077
1078- Timestamp Support:
1079
1080		When CONFIG_TIMESTAMP is selected, the timestamp
1081		(date and time) of an image is printed by image
1082		commands like bootm or iminfo. This option is
1083		automatically enabled when you select CONFIG_CMD_DATE .
1084
1085- Partition Labels (disklabels) Supported:
1086		Zero or more of the following:
1087		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1088		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1089				       Intel architecture, USB sticks, etc.
1090		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1091		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1092				       bootloader.  Note 2TB partition limit; see
1093				       disk/part_efi.c
1094		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1095
1096		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1097		CONFIG_CMD_SCSI) you must configure support for at
1098		least one non-MTD partition type as well.
1099
1100- IDE Reset method:
1101		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1102		board configurations files but used nowhere!
1103
1104		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1105		be performed by calling the function
1106			ide_set_reset(int reset)
1107		which has to be defined in a board specific file
1108
1109- ATAPI Support:
1110		CONFIG_ATAPI
1111
1112		Set this to enable ATAPI support.
1113
1114- LBA48 Support
1115		CONFIG_LBA48
1116
1117		Set this to enable support for disks larger than 137GB
1118		Also look at CONFIG_SYS_64BIT_LBA.
1119		Whithout these , LBA48 support uses 32bit variables and will 'only'
1120		support disks up to 2.1TB.
1121
1122		CONFIG_SYS_64BIT_LBA:
1123			When enabled, makes the IDE subsystem use 64bit sector addresses.
1124			Default is 32bit.
1125
1126- SCSI Support:
1127		At the moment only there is only support for the
1128		SYM53C8XX SCSI controller; define
1129		CONFIG_SCSI_SYM53C8XX to enable it.
1130
1131		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1132		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1133		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1134		maximum numbers of LUNs, SCSI ID's and target
1135		devices.
1136		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1137
1138		The environment variable 'scsidevs' is set to the number of
1139		SCSI devices found during the last scan.
1140
1141- NETWORK Support (PCI):
1142		CONFIG_E1000
1143		Support for Intel 8254x/8257x gigabit chips.
1144
1145		CONFIG_E1000_SPI
1146		Utility code for direct access to the SPI bus on Intel 8257x.
1147		This does not do anything useful unless you set at least one
1148		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1149
1150		CONFIG_E1000_SPI_GENERIC
1151		Allow generic access to the SPI bus on the Intel 8257x, for
1152		example with the "sspi" command.
1153
1154		CONFIG_CMD_E1000
1155		Management command for E1000 devices.  When used on devices
1156		with SPI support you can reprogram the EEPROM from U-Boot.
1157
1158		CONFIG_E1000_FALLBACK_MAC
1159		default MAC for empty EEPROM after production.
1160
1161		CONFIG_EEPRO100
1162		Support for Intel 82557/82559/82559ER chips.
1163		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1164		write routine for first time initialisation.
1165
1166		CONFIG_TULIP
1167		Support for Digital 2114x chips.
1168		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1169		modem chip initialisation (KS8761/QS6611).
1170
1171		CONFIG_NATSEMI
1172		Support for National dp83815 chips.
1173
1174		CONFIG_NS8382X
1175		Support for National dp8382[01] gigabit chips.
1176
1177- NETWORK Support (other):
1178
1179		CONFIG_DRIVER_AT91EMAC
1180		Support for AT91RM9200 EMAC.
1181
1182			CONFIG_RMII
1183			Define this to use reduced MII inteface
1184
1185			CONFIG_DRIVER_AT91EMAC_QUIET
1186			If this defined, the driver is quiet.
1187			The driver doen't show link status messages.
1188
1189		CONFIG_CALXEDA_XGMAC
1190		Support for the Calxeda XGMAC device
1191
1192		CONFIG_LAN91C96
1193		Support for SMSC's LAN91C96 chips.
1194
1195			CONFIG_LAN91C96_BASE
1196			Define this to hold the physical address
1197			of the LAN91C96's I/O space
1198
1199			CONFIG_LAN91C96_USE_32_BIT
1200			Define this to enable 32 bit addressing
1201
1202		CONFIG_SMC91111
1203		Support for SMSC's LAN91C111 chip
1204
1205			CONFIG_SMC91111_BASE
1206			Define this to hold the physical address
1207			of the device (I/O space)
1208
1209			CONFIG_SMC_USE_32_BIT
1210			Define this if data bus is 32 bits
1211
1212			CONFIG_SMC_USE_IOFUNCS
1213			Define this to use i/o functions instead of macros
1214			(some hardware wont work with macros)
1215
1216		CONFIG_DRIVER_TI_EMAC
1217		Support for davinci emac
1218
1219			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1220			Define this if you have more then 3 PHYs.
1221
1222		CONFIG_FTGMAC100
1223		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1224
1225			CONFIG_FTGMAC100_EGIGA
1226			Define this to use GE link update with gigabit PHY.
1227			Define this if FTGMAC100 is connected to gigabit PHY.
1228			If your system has 10/100 PHY only, it might not occur
1229			wrong behavior. Because PHY usually return timeout or
1230			useless data when polling gigabit status and gigabit
1231			control registers. This behavior won't affect the
1232			correctnessof 10/100 link speed update.
1233
1234		CONFIG_SMC911X
1235		Support for SMSC's LAN911x and LAN921x chips
1236
1237			CONFIG_SMC911X_BASE
1238			Define this to hold the physical address
1239			of the device (I/O space)
1240
1241			CONFIG_SMC911X_32_BIT
1242			Define this if data bus is 32 bits
1243
1244			CONFIG_SMC911X_16_BIT
1245			Define this if data bus is 16 bits. If your processor
1246			automatically converts one 32 bit word to two 16 bit
1247			words you may also try CONFIG_SMC911X_32_BIT.
1248
1249		CONFIG_SH_ETHER
1250		Support for Renesas on-chip Ethernet controller
1251
1252			CONFIG_SH_ETHER_USE_PORT
1253			Define the number of ports to be used
1254
1255			CONFIG_SH_ETHER_PHY_ADDR
1256			Define the ETH PHY's address
1257
1258			CONFIG_SH_ETHER_CACHE_WRITEBACK
1259			If this option is set, the driver enables cache flush.
1260
1261- TPM Support:
1262		CONFIG_TPM
1263		Support TPM devices.
1264
1265		CONFIG_TPM_TIS_I2C
1266		Support for i2c bus TPM devices. Only one device
1267		per system is supported at this time.
1268
1269			CONFIG_TPM_TIS_I2C_BUS_NUMBER
1270			Define the the i2c bus number for the TPM device
1271
1272			CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS
1273			Define the TPM's address on the i2c bus
1274
1275			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1276			Define the burst count bytes upper limit
1277
1278		CONFIG_TPM_ATMEL_TWI
1279		Support for Atmel TWI TPM device. Requires I2C support.
1280
1281		CONFIG_TPM_TIS_LPC
1282		Support for generic parallel port TPM devices. Only one device
1283		per system is supported at this time.
1284
1285			CONFIG_TPM_TIS_BASE_ADDRESS
1286			Base address where the generic TPM device is mapped
1287			to. Contemporary x86 systems usually map it at
1288			0xfed40000.
1289
1290		CONFIG_CMD_TPM
1291		Add tpm monitor functions.
1292		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1293		provides monitor access to authorized functions.
1294
1295		CONFIG_TPM
1296		Define this to enable the TPM support library which provides
1297		functional interfaces to some TPM commands.
1298		Requires support for a TPM device.
1299
1300		CONFIG_TPM_AUTH_SESSIONS
1301		Define this to enable authorized functions in the TPM library.
1302		Requires CONFIG_TPM and CONFIG_SHA1.
1303
1304- USB Support:
1305		At the moment only the UHCI host controller is
1306		supported (PIP405, MIP405, MPC5200); define
1307		CONFIG_USB_UHCI to enable it.
1308		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1309		and define CONFIG_USB_STORAGE to enable the USB
1310		storage devices.
1311		Note:
1312		Supported are USB Keyboards and USB Floppy drives
1313		(TEAC FD-05PUB).
1314		MPC5200 USB requires additional defines:
1315			CONFIG_USB_CLOCK
1316				for 528 MHz Clock: 0x0001bbbb
1317			CONFIG_PSC3_USB
1318				for USB on PSC3
1319			CONFIG_USB_CONFIG
1320				for differential drivers: 0x00001000
1321				for single ended drivers: 0x00005000
1322				for differential drivers on PSC3: 0x00000100
1323				for single ended drivers on PSC3: 0x00004100
1324			CONFIG_SYS_USB_EVENT_POLL
1325				May be defined to allow interrupt polling
1326				instead of using asynchronous interrupts
1327
1328		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1329		txfilltuning field in the EHCI controller on reset.
1330
1331		CONFIG_USB_HUB_MIN_POWER_ON_DELAY defines the minimum
1332		interval for usb hub power-on delay.(minimum 100msec)
1333
1334- USB Device:
1335		Define the below if you wish to use the USB console.
1336		Once firmware is rebuilt from a serial console issue the
1337		command "setenv stdin usbtty; setenv stdout usbtty" and
1338		attach your USB cable. The Unix command "dmesg" should print
1339		it has found a new device. The environment variable usbtty
1340		can be set to gserial or cdc_acm to enable your device to
1341		appear to a USB host as a Linux gserial device or a
1342		Common Device Class Abstract Control Model serial device.
1343		If you select usbtty = gserial you should be able to enumerate
1344		a Linux host by
1345		# modprobe usbserial vendor=0xVendorID product=0xProductID
1346		else if using cdc_acm, simply setting the environment
1347		variable usbtty to be cdc_acm should suffice. The following
1348		might be defined in YourBoardName.h
1349
1350			CONFIG_USB_DEVICE
1351			Define this to build a UDC device
1352
1353			CONFIG_USB_TTY
1354			Define this to have a tty type of device available to
1355			talk to the UDC device
1356
1357			CONFIG_USBD_HS
1358			Define this to enable the high speed support for usb
1359			device and usbtty. If this feature is enabled, a routine
1360			int is_usbd_high_speed(void)
1361			also needs to be defined by the driver to dynamically poll
1362			whether the enumeration has succeded at high speed or full
1363			speed.
1364
1365			CONFIG_SYS_CONSOLE_IS_IN_ENV
1366			Define this if you want stdin, stdout &/or stderr to
1367			be set to usbtty.
1368
1369			mpc8xx:
1370				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1371				Derive USB clock from external clock "blah"
1372				- CONFIG_SYS_USB_EXTC_CLK 0x02
1373
1374				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1375				Derive USB clock from brgclk
1376				- CONFIG_SYS_USB_BRG_CLK 0x04
1377
1378		If you have a USB-IF assigned VendorID then you may wish to
1379		define your own vendor specific values either in BoardName.h
1380		or directly in usbd_vendor_info.h. If you don't define
1381		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1382		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1383		should pretend to be a Linux device to it's target host.
1384
1385			CONFIG_USBD_MANUFACTURER
1386			Define this string as the name of your company for
1387			- CONFIG_USBD_MANUFACTURER "my company"
1388
1389			CONFIG_USBD_PRODUCT_NAME
1390			Define this string as the name of your product
1391			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1392
1393			CONFIG_USBD_VENDORID
1394			Define this as your assigned Vendor ID from the USB
1395			Implementors Forum. This *must* be a genuine Vendor ID
1396			to avoid polluting the USB namespace.
1397			- CONFIG_USBD_VENDORID 0xFFFF
1398
1399			CONFIG_USBD_PRODUCTID
1400			Define this as the unique Product ID
1401			for your device
1402			- CONFIG_USBD_PRODUCTID 0xFFFF
1403
1404		Some USB device drivers may need to check USB cable attachment.
1405		In this case you can enable following config in BoardName.h:
1406			CONFIG_USB_CABLE_CHECK
1407			This enables function definition:
1408			- usb_cable_connected() in include/usb.h
1409			Implementation of this function is board-specific.
1410
1411- ULPI Layer Support:
1412		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1413		the generic ULPI layer. The generic layer accesses the ULPI PHY
1414		via the platform viewport, so you need both the genric layer and
1415		the viewport enabled. Currently only Chipidea/ARC based
1416		viewport is supported.
1417		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1418		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1419		If your ULPI phy needs a different reference clock than the
1420		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1421		the appropriate value in Hz.
1422
1423- MMC Support:
1424		The MMC controller on the Intel PXA is supported. To
1425		enable this define CONFIG_MMC. The MMC can be
1426		accessed from the boot prompt by mapping the device
1427		to physical memory similar to flash. Command line is
1428		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1429		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1430
1431		CONFIG_SH_MMCIF
1432		Support for Renesas on-chip MMCIF controller
1433
1434			CONFIG_SH_MMCIF_ADDR
1435			Define the base address of MMCIF registers
1436
1437			CONFIG_SH_MMCIF_CLK
1438			Define the clock frequency for MMCIF
1439
1440- USB Device Firmware Update (DFU) class support:
1441		CONFIG_DFU_FUNCTION
1442		This enables the USB portion of the DFU USB class
1443
1444		CONFIG_CMD_DFU
1445		This enables the command "dfu" which is used to have
1446		U-Boot create a DFU class device via USB.  This command
1447		requires that the "dfu_alt_info" environment variable be
1448		set and define the alt settings to expose to the host.
1449
1450		CONFIG_DFU_MMC
1451		This enables support for exposing (e)MMC devices via DFU.
1452
1453		CONFIG_DFU_NAND
1454		This enables support for exposing NAND devices via DFU.
1455
1456		CONFIG_DFU_RAM
1457		This enables support for exposing RAM via DFU.
1458		Note: DFU spec refer to non-volatile memory usage, but
1459		allow usages beyond the scope of spec - here RAM usage,
1460		one that would help mostly the developer.
1461
1462		CONFIG_SYS_DFU_DATA_BUF_SIZE
1463		Dfu transfer uses a buffer before writing data to the
1464		raw storage device. Make the size (in bytes) of this buffer
1465		configurable. The size of this buffer is also configurable
1466		through the "dfu_bufsiz" environment variable.
1467
1468		CONFIG_SYS_DFU_MAX_FILE_SIZE
1469		When updating files rather than the raw storage device,
1470		we use a static buffer to copy the file into and then write
1471		the buffer once we've been given the whole file.  Define
1472		this to the maximum filesize (in bytes) for the buffer.
1473		Default is 4 MiB if undefined.
1474
1475- Journaling Flash filesystem support:
1476		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1477		CONFIG_JFFS2_NAND_DEV
1478		Define these for a default partition on a NAND device
1479
1480		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1481		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1482		Define these for a default partition on a NOR device
1483
1484		CONFIG_SYS_JFFS_CUSTOM_PART
1485		Define this to create an own partition. You have to provide a
1486		function struct part_info* jffs2_part_info(int part_num)
1487
1488		If you define only one JFFS2 partition you may also want to
1489		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1490		to disable the command chpart. This is the default when you
1491		have not defined a custom partition
1492
1493- FAT(File Allocation Table) filesystem write function support:
1494		CONFIG_FAT_WRITE
1495
1496		Define this to enable support for saving memory data as a
1497		file in FAT formatted partition.
1498
1499		This will also enable the command "fatwrite" enabling the
1500		user to write files to FAT.
1501
1502CBFS (Coreboot Filesystem) support
1503		CONFIG_CMD_CBFS
1504
1505		Define this to enable support for reading from a Coreboot
1506		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1507		and cbfsload.
1508
1509- Keyboard Support:
1510		CONFIG_ISA_KEYBOARD
1511
1512		Define this to enable standard (PC-Style) keyboard
1513		support
1514
1515		CONFIG_I8042_KBD
1516		Standard PC keyboard driver with US (is default) and
1517		GERMAN key layout (switch via environment 'keymap=de') support.
1518		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1519		for cfb_console. Supports cursor blinking.
1520
1521		CONFIG_CROS_EC_KEYB
1522		Enables a Chrome OS keyboard using the CROS_EC interface.
1523		This uses CROS_EC to communicate with a second microcontroller
1524		which provides key scans on request.
1525
1526- Video support:
1527		CONFIG_VIDEO
1528
1529		Define this to enable video support (for output to
1530		video).
1531
1532		CONFIG_VIDEO_CT69000
1533
1534		Enable Chips & Technologies 69000 Video chip
1535
1536		CONFIG_VIDEO_SMI_LYNXEM
1537		Enable Silicon Motion SMI 712/710/810 Video chip. The
1538		video output is selected via environment 'videoout'
1539		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1540		assumed.
1541
1542		For the CT69000 and SMI_LYNXEM drivers, videomode is
1543		selected via environment 'videomode'. Two different ways
1544		are possible:
1545		- "videomode=num"   'num' is a standard LiLo mode numbers.
1546		Following standard modes are supported	(* is default):
1547
1548		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1549		-------------+---------------------------------------------
1550		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1551		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1552		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1553		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1554		-------------+---------------------------------------------
1555		(i.e. setenv videomode 317; saveenv; reset;)
1556
1557		- "videomode=bootargs" all the video parameters are parsed
1558		from the bootargs. (See drivers/video/videomodes.c)
1559
1560
1561		CONFIG_VIDEO_SED13806
1562		Enable Epson SED13806 driver. This driver supports 8bpp
1563		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1564		or CONFIG_VIDEO_SED13806_16BPP
1565
1566		CONFIG_FSL_DIU_FB
1567		Enable the Freescale DIU video driver.	Reference boards for
1568		SOCs that have a DIU should define this macro to enable DIU
1569		support, and should also define these other macros:
1570
1571			CONFIG_SYS_DIU_ADDR
1572			CONFIG_VIDEO
1573			CONFIG_CMD_BMP
1574			CONFIG_CFB_CONSOLE
1575			CONFIG_VIDEO_SW_CURSOR
1576			CONFIG_VGA_AS_SINGLE_DEVICE
1577			CONFIG_VIDEO_LOGO
1578			CONFIG_VIDEO_BMP_LOGO
1579
1580		The DIU driver will look for the 'video-mode' environment
1581		variable, and if defined, enable the DIU as a console during
1582		boot.  See the documentation file README.video for a
1583		description of this variable.
1584
1585		CONFIG_VIDEO_VGA
1586
1587		Enable the VGA video / BIOS for x86. The alternative if you
1588		are using coreboot is to use the coreboot frame buffer
1589		driver.
1590
1591
1592- Keyboard Support:
1593		CONFIG_KEYBOARD
1594
1595		Define this to enable a custom keyboard support.
1596		This simply calls drv_keyboard_init() which must be
1597		defined in your board-specific files.
1598		The only board using this so far is RBC823.
1599
1600- LCD Support:	CONFIG_LCD
1601
1602		Define this to enable LCD support (for output to LCD
1603		display); also select one of the supported displays
1604		by defining one of these:
1605
1606		CONFIG_ATMEL_LCD:
1607
1608			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1609
1610		CONFIG_NEC_NL6448AC33:
1611
1612			NEC NL6448AC33-18. Active, color, single scan.
1613
1614		CONFIG_NEC_NL6448BC20
1615
1616			NEC NL6448BC20-08. 6.5", 640x480.
1617			Active, color, single scan.
1618
1619		CONFIG_NEC_NL6448BC33_54
1620
1621			NEC NL6448BC33-54. 10.4", 640x480.
1622			Active, color, single scan.
1623
1624		CONFIG_SHARP_16x9
1625
1626			Sharp 320x240. Active, color, single scan.
1627			It isn't 16x9, and I am not sure what it is.
1628
1629		CONFIG_SHARP_LQ64D341
1630
1631			Sharp LQ64D341 display, 640x480.
1632			Active, color, single scan.
1633
1634		CONFIG_HLD1045
1635
1636			HLD1045 display, 640x480.
1637			Active, color, single scan.
1638
1639		CONFIG_OPTREX_BW
1640
1641			Optrex	 CBL50840-2 NF-FW 99 22 M5
1642			or
1643			Hitachi	 LMG6912RPFC-00T
1644			or
1645			Hitachi	 SP14Q002
1646
1647			320x240. Black & white.
1648
1649		Normally display is black on white background; define
1650		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1651
1652		CONFIG_LCD_ALIGNMENT
1653
1654		Normally the LCD is page-aligned (tyically 4KB). If this is
1655		defined then the LCD will be aligned to this value instead.
1656		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1657		here, since it is cheaper to change data cache settings on
1658		a per-section basis.
1659
1660		CONFIG_CONSOLE_SCROLL_LINES
1661
1662		When the console need to be scrolled, this is the number of
1663		lines to scroll by. It defaults to 1. Increasing this makes
1664		the console jump but can help speed up operation when scrolling
1665		is slow.
1666
1667		CONFIG_LCD_BMP_RLE8
1668
1669		Support drawing of RLE8-compressed bitmaps on the LCD.
1670
1671		CONFIG_I2C_EDID
1672
1673		Enables an 'i2c edid' command which can read EDID
1674		information over I2C from an attached LCD display.
1675
1676- Splash Screen Support: CONFIG_SPLASH_SCREEN
1677
1678		If this option is set, the environment is checked for
1679		a variable "splashimage". If found, the usual display
1680		of logo, copyright and system information on the LCD
1681		is suppressed and the BMP image at the address
1682		specified in "splashimage" is loaded instead. The
1683		console is redirected to the "nulldev", too. This
1684		allows for a "silent" boot where a splash screen is
1685		loaded very quickly after power-on.
1686
1687		CONFIG_SPLASHIMAGE_GUARD
1688
1689		If this option is set, then U-Boot will prevent the environment
1690		variable "splashimage" from being set to a problematic address
1691		(see README.displaying-bmps and README.arm-unaligned-accesses).
1692		This option is useful for targets where, due to alignment
1693		restrictions, an improperly aligned BMP image will cause a data
1694		abort. If you think you will not have problems with unaligned
1695		accesses (for example because your toolchain prevents them)
1696		there is no need to set this option.
1697
1698		CONFIG_SPLASH_SCREEN_ALIGN
1699
1700		If this option is set the splash image can be freely positioned
1701		on the screen. Environment variable "splashpos" specifies the
1702		position as "x,y". If a positive number is given it is used as
1703		number of pixel from left/top. If a negative number is given it
1704		is used as number of pixel from right/bottom. You can also
1705		specify 'm' for centering the image.
1706
1707		Example:
1708		setenv splashpos m,m
1709			=> image at center of screen
1710
1711		setenv splashpos 30,20
1712			=> image at x = 30 and y = 20
1713
1714		setenv splashpos -10,m
1715			=> vertically centered image
1716			   at x = dspWidth - bmpWidth - 9
1717
1718- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1719
1720		If this option is set, additionally to standard BMP
1721		images, gzipped BMP images can be displayed via the
1722		splashscreen support or the bmp command.
1723
1724- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1725
1726		If this option is set, 8-bit RLE compressed BMP images
1727		can be displayed via the splashscreen support or the
1728		bmp command.
1729
1730- Do compresssing for memory range:
1731		CONFIG_CMD_ZIP
1732
1733		If this option is set, it would use zlib deflate method
1734		to compress the specified memory at its best effort.
1735
1736- Compression support:
1737		CONFIG_GZIP
1738
1739		Enabled by default to support gzip compressed images.
1740
1741		CONFIG_BZIP2
1742
1743		If this option is set, support for bzip2 compressed
1744		images is included. If not, only uncompressed and gzip
1745		compressed images are supported.
1746
1747		NOTE: the bzip2 algorithm requires a lot of RAM, so
1748		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1749		be at least 4MB.
1750
1751		CONFIG_LZMA
1752
1753		If this option is set, support for lzma compressed
1754		images is included.
1755
1756		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1757		requires an amount of dynamic memory that is given by the
1758		formula:
1759
1760			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1761
1762		Where lc and lp stand for, respectively, Literal context bits
1763		and Literal pos bits.
1764
1765		This value is upper-bounded by 14MB in the worst case. Anyway,
1766		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1767		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1768		a very small buffer.
1769
1770		Use the lzmainfo tool to determinate the lc and lp values and
1771		then calculate the amount of needed dynamic memory (ensuring
1772		the appropriate CONFIG_SYS_MALLOC_LEN value).
1773
1774		CONFIG_LZO
1775
1776		If this option is set, support for LZO compressed images
1777		is included.
1778
1779- MII/PHY support:
1780		CONFIG_PHY_ADDR
1781
1782		The address of PHY on MII bus.
1783
1784		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1785
1786		The clock frequency of the MII bus
1787
1788		CONFIG_PHY_GIGE
1789
1790		If this option is set, support for speed/duplex
1791		detection of gigabit PHY is included.
1792
1793		CONFIG_PHY_RESET_DELAY
1794
1795		Some PHY like Intel LXT971A need extra delay after
1796		reset before any MII register access is possible.
1797		For such PHY, set this option to the usec delay
1798		required. (minimum 300usec for LXT971A)
1799
1800		CONFIG_PHY_CMD_DELAY (ppc4xx)
1801
1802		Some PHY like Intel LXT971A need extra delay after
1803		command issued before MII status register can be read
1804
1805- Ethernet address:
1806		CONFIG_ETHADDR
1807		CONFIG_ETH1ADDR
1808		CONFIG_ETH2ADDR
1809		CONFIG_ETH3ADDR
1810		CONFIG_ETH4ADDR
1811		CONFIG_ETH5ADDR
1812
1813		Define a default value for Ethernet address to use
1814		for the respective Ethernet interface, in case this
1815		is not determined automatically.
1816
1817- IP address:
1818		CONFIG_IPADDR
1819
1820		Define a default value for the IP address to use for
1821		the default Ethernet interface, in case this is not
1822		determined through e.g. bootp.
1823		(Environment variable "ipaddr")
1824
1825- Server IP address:
1826		CONFIG_SERVERIP
1827
1828		Defines a default value for the IP address of a TFTP
1829		server to contact when using the "tftboot" command.
1830		(Environment variable "serverip")
1831
1832		CONFIG_KEEP_SERVERADDR
1833
1834		Keeps the server's MAC address, in the env 'serveraddr'
1835		for passing to bootargs (like Linux's netconsole option)
1836
1837- Gateway IP address:
1838		CONFIG_GATEWAYIP
1839
1840		Defines a default value for the IP address of the
1841		default router where packets to other networks are
1842		sent to.
1843		(Environment variable "gatewayip")
1844
1845- Subnet mask:
1846		CONFIG_NETMASK
1847
1848		Defines a default value for the subnet mask (or
1849		routing prefix) which is used to determine if an IP
1850		address belongs to the local subnet or needs to be
1851		forwarded through a router.
1852		(Environment variable "netmask")
1853
1854- Multicast TFTP Mode:
1855		CONFIG_MCAST_TFTP
1856
1857		Defines whether you want to support multicast TFTP as per
1858		rfc-2090; for example to work with atftp.  Lets lots of targets
1859		tftp down the same boot image concurrently.  Note: the Ethernet
1860		driver in use must provide a function: mcast() to join/leave a
1861		multicast group.
1862
1863- BOOTP Recovery Mode:
1864		CONFIG_BOOTP_RANDOM_DELAY
1865
1866		If you have many targets in a network that try to
1867		boot using BOOTP, you may want to avoid that all
1868		systems send out BOOTP requests at precisely the same
1869		moment (which would happen for instance at recovery
1870		from a power failure, when all systems will try to
1871		boot, thus flooding the BOOTP server. Defining
1872		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1873		inserted before sending out BOOTP requests. The
1874		following delays are inserted then:
1875
1876		1st BOOTP request:	delay 0 ... 1 sec
1877		2nd BOOTP request:	delay 0 ... 2 sec
1878		3rd BOOTP request:	delay 0 ... 4 sec
1879		4th and following
1880		BOOTP requests:		delay 0 ... 8 sec
1881
1882- DHCP Advanced Options:
1883		You can fine tune the DHCP functionality by defining
1884		CONFIG_BOOTP_* symbols:
1885
1886		CONFIG_BOOTP_SUBNETMASK
1887		CONFIG_BOOTP_GATEWAY
1888		CONFIG_BOOTP_HOSTNAME
1889		CONFIG_BOOTP_NISDOMAIN
1890		CONFIG_BOOTP_BOOTPATH
1891		CONFIG_BOOTP_BOOTFILESIZE
1892		CONFIG_BOOTP_DNS
1893		CONFIG_BOOTP_DNS2
1894		CONFIG_BOOTP_SEND_HOSTNAME
1895		CONFIG_BOOTP_NTPSERVER
1896		CONFIG_BOOTP_TIMEOFFSET
1897		CONFIG_BOOTP_VENDOREX
1898		CONFIG_BOOTP_MAY_FAIL
1899
1900		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1901		environment variable, not the BOOTP server.
1902
1903		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1904		after the configured retry count, the call will fail
1905		instead of starting over.  This can be used to fail over
1906		to Link-local IP address configuration if the DHCP server
1907		is not available.
1908
1909		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1910		serverip from a DHCP server, it is possible that more
1911		than one DNS serverip is offered to the client.
1912		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1913		serverip will be stored in the additional environment
1914		variable "dnsip2". The first DNS serverip is always
1915		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1916		is defined.
1917
1918		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1919		to do a dynamic update of a DNS server. To do this, they
1920		need the hostname of the DHCP requester.
1921		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1922		of the "hostname" environment variable is passed as
1923		option 12 to the DHCP server.
1924
1925		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1926
1927		A 32bit value in microseconds for a delay between
1928		receiving a "DHCP Offer" and sending the "DHCP Request".
1929		This fixes a problem with certain DHCP servers that don't
1930		respond 100% of the time to a "DHCP request". E.g. On an
1931		AT91RM9200 processor running at 180MHz, this delay needed
1932		to be *at least* 15,000 usec before a Windows Server 2003
1933		DHCP server would reply 100% of the time. I recommend at
1934		least 50,000 usec to be safe. The alternative is to hope
1935		that one of the retries will be successful but note that
1936		the DHCP timeout and retry process takes a longer than
1937		this delay.
1938
1939 - Link-local IP address negotiation:
1940		Negotiate with other link-local clients on the local network
1941		for an address that doesn't require explicit configuration.
1942		This is especially useful if a DHCP server cannot be guaranteed
1943		to exist in all environments that the device must operate.
1944
1945		See doc/README.link-local for more information.
1946
1947 - CDP Options:
1948		CONFIG_CDP_DEVICE_ID
1949
1950		The device id used in CDP trigger frames.
1951
1952		CONFIG_CDP_DEVICE_ID_PREFIX
1953
1954		A two character string which is prefixed to the MAC address
1955		of the device.
1956
1957		CONFIG_CDP_PORT_ID
1958
1959		A printf format string which contains the ascii name of
1960		the port. Normally is set to "eth%d" which sets
1961		eth0 for the first Ethernet, eth1 for the second etc.
1962
1963		CONFIG_CDP_CAPABILITIES
1964
1965		A 32bit integer which indicates the device capabilities;
1966		0x00000010 for a normal host which does not forwards.
1967
1968		CONFIG_CDP_VERSION
1969
1970		An ascii string containing the version of the software.
1971
1972		CONFIG_CDP_PLATFORM
1973
1974		An ascii string containing the name of the platform.
1975
1976		CONFIG_CDP_TRIGGER
1977
1978		A 32bit integer sent on the trigger.
1979
1980		CONFIG_CDP_POWER_CONSUMPTION
1981
1982		A 16bit integer containing the power consumption of the
1983		device in .1 of milliwatts.
1984
1985		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1986
1987		A byte containing the id of the VLAN.
1988
1989- Status LED:	CONFIG_STATUS_LED
1990
1991		Several configurations allow to display the current
1992		status using a LED. For instance, the LED will blink
1993		fast while running U-Boot code, stop blinking as
1994		soon as a reply to a BOOTP request was received, and
1995		start blinking slow once the Linux kernel is running
1996		(supported by a status LED driver in the Linux
1997		kernel). Defining CONFIG_STATUS_LED enables this
1998		feature in U-Boot.
1999
2000- CAN Support:	CONFIG_CAN_DRIVER
2001
2002		Defining CONFIG_CAN_DRIVER enables CAN driver support
2003		on those systems that support this (optional)
2004		feature, like the TQM8xxL modules.
2005
2006- I2C Support:	CONFIG_SYS_I2C
2007
2008		This enable the NEW i2c subsystem, and will allow you to use
2009		i2c commands at the u-boot command line (as long as you set
2010		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
2011		based realtime clock chips or other i2c devices. See
2012		common/cmd_i2c.c for a description of the command line
2013		interface.
2014
2015		ported i2c driver to the new framework:
2016		- drivers/i2c/soft_i2c.c:
2017		  - activate first bus with CONFIG_SYS_I2C_SOFT define
2018		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
2019		    for defining speed and slave address
2020		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
2021		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
2022		    for defining speed and slave address
2023		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
2024		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
2025		    for defining speed and slave address
2026		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
2027		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
2028		    for defining speed and slave address
2029
2030		- drivers/i2c/fsl_i2c.c:
2031		  - activate i2c driver with CONFIG_SYS_I2C_FSL
2032		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
2033		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
2034		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
2035		    bus.
2036		  - If your board supports a second fsl i2c bus, define
2037		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
2038		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
2039		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
2040		    second bus.
2041
2042		- drivers/i2c/tegra_i2c.c:
2043		  - activate this driver with CONFIG_SYS_I2C_TEGRA
2044		  - This driver adds 4 i2c buses with a fix speed from
2045		    100000 and the slave addr 0!
2046
2047		- drivers/i2c/ppc4xx_i2c.c
2048		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
2049		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
2050		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
2051
2052		- drivers/i2c/i2c_mxc.c
2053		  - activate this driver with CONFIG_SYS_I2C_MXC
2054		  - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
2055		  - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
2056		  - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
2057		  - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
2058		  - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
2059		  - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
2060		If thoses defines are not set, default value is 100000
2061		for speed, and 0 for slave.
2062
2063		- drivers/i2c/rcar_i2c.c:
2064		  - activate this driver with CONFIG_SYS_I2C_RCAR
2065		  - This driver adds 4 i2c buses
2066
2067		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
2068		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
2069		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
2070		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
2071		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
2072		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
2073		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
2074		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
2075		  - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
2076
2077		- drivers/i2c/sh_i2c.c:
2078		  - activate this driver with CONFIG_SYS_I2C_SH
2079		  - This driver adds from 2 to 5 i2c buses
2080
2081		  - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
2082		  - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
2083		  - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
2084		  - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
2085		  - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
2086		  - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
2087		  - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
2088		  - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
2089		  - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
2090		  - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
2091		  - CONFIG_SYS_I2C_SH_BASE5 for setting the register channel 5
2092		  - CONFIG_SYS_I2C_SH_SPEED5 for for the speed channel 5
2093		  - CONFIF_SYS_I2C_SH_NUM_CONTROLLERS for nummber of i2c buses
2094
2095		- drivers/i2c/omap24xx_i2c.c
2096		  - activate this driver with CONFIG_SYS_I2C_OMAP24XX
2097		  - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
2098		  - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
2099		  - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
2100		  - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
2101		  - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
2102		  - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
2103		  - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
2104		  - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
2105		  - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
2106		  - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
2107
2108		- drivers/i2c/zynq_i2c.c
2109		  - activate this driver with CONFIG_SYS_I2C_ZYNQ
2110		  - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
2111		  - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
2112
2113		additional defines:
2114
2115		CONFIG_SYS_NUM_I2C_BUSES
2116		Hold the number of i2c busses you want to use. If you
2117		don't use/have i2c muxes on your i2c bus, this
2118		is equal to CONFIG_SYS_NUM_I2C_ADAPTERS, and you can
2119		omit this define.
2120
2121		CONFIG_SYS_I2C_DIRECT_BUS
2122		define this, if you don't use i2c muxes on your hardware.
2123		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2124		omit this define.
2125
2126		CONFIG_SYS_I2C_MAX_HOPS
2127		define how many muxes are maximal consecutively connected
2128		on one i2c bus. If you not use i2c muxes, omit this
2129		define.
2130
2131		CONFIG_SYS_I2C_BUSES
2132		hold a list of busses you want to use, only used if
2133		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2134		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2135		CONFIG_SYS_NUM_I2C_BUSES = 9:
2136
2137		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
2138					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2139					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2140					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2141					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2142					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2143					{1, {I2C_NULL_HOP}}, \
2144					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2145					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2146					}
2147
2148		which defines
2149			bus 0 on adapter 0 without a mux
2150			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2151			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2152			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2153			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2154			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2155			bus 6 on adapter 1 without a mux
2156			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2157			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2158
2159		If you do not have i2c muxes on your board, omit this define.
2160
2161- Legacy I2C Support:	CONFIG_HARD_I2C
2162
2163		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2164		provides the following compelling advantages:
2165
2166		- more than one i2c adapter is usable
2167		- approved multibus support
2168		- better i2c mux support
2169
2170		** Please consider updating your I2C driver now. **
2171
2172		These enable legacy I2C serial bus commands. Defining
2173		CONFIG_HARD_I2C will include the appropriate I2C driver
2174		for the selected CPU.
2175
2176		This will allow you to use i2c commands at the u-boot
2177		command line (as long as you set CONFIG_CMD_I2C in
2178		CONFIG_COMMANDS) and communicate with i2c based realtime
2179		clock chips. See common/cmd_i2c.c for a description of the
2180		command line interface.
2181
2182		CONFIG_HARD_I2C selects a hardware I2C controller.
2183
2184		There are several other quantities that must also be
2185		defined when you define CONFIG_HARD_I2C.
2186
2187		In both cases you will need to define CONFIG_SYS_I2C_SPEED
2188		to be the frequency (in Hz) at which you wish your i2c bus
2189		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2190		the CPU's i2c node address).
2191
2192		Now, the u-boot i2c code for the mpc8xx
2193		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2194		and so its address should therefore be cleared to 0 (See,
2195		eg, MPC823e User's Manual p.16-473). So, set
2196		CONFIG_SYS_I2C_SLAVE to 0.
2197
2198		CONFIG_SYS_I2C_INIT_MPC5XXX
2199
2200		When a board is reset during an i2c bus transfer
2201		chips might think that the current transfer is still
2202		in progress.  Reset the slave devices by sending start
2203		commands until the slave device responds.
2204
2205		That's all that's required for CONFIG_HARD_I2C.
2206
2207		If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2208		then the following macros need to be defined (examples are
2209		from include/configs/lwmon.h):
2210
2211		I2C_INIT
2212
2213		(Optional). Any commands necessary to enable the I2C
2214		controller or configure ports.
2215
2216		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2217
2218		I2C_PORT
2219
2220		(Only for MPC8260 CPU). The I/O port to use (the code
2221		assumes both bits are on the same port). Valid values
2222		are 0..3 for ports A..D.
2223
2224		I2C_ACTIVE
2225
2226		The code necessary to make the I2C data line active
2227		(driven).  If the data line is open collector, this
2228		define can be null.
2229
2230		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2231
2232		I2C_TRISTATE
2233
2234		The code necessary to make the I2C data line tri-stated
2235		(inactive).  If the data line is open collector, this
2236		define can be null.
2237
2238		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2239
2240		I2C_READ
2241
2242		Code that returns true if the I2C data line is high,
2243		false if it is low.
2244
2245		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2246
2247		I2C_SDA(bit)
2248
2249		If <bit> is true, sets the I2C data line high. If it
2250		is false, it clears it (low).
2251
2252		eg: #define I2C_SDA(bit) \
2253			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2254			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2255
2256		I2C_SCL(bit)
2257
2258		If <bit> is true, sets the I2C clock line high. If it
2259		is false, it clears it (low).
2260
2261		eg: #define I2C_SCL(bit) \
2262			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2263			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2264
2265		I2C_DELAY
2266
2267		This delay is invoked four times per clock cycle so this
2268		controls the rate of data transfer.  The data rate thus
2269		is 1 / (I2C_DELAY * 4). Often defined to be something
2270		like:
2271
2272		#define I2C_DELAY  udelay(2)
2273
2274		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2275
2276		If your arch supports the generic GPIO framework (asm/gpio.h),
2277		then you may alternatively define the two GPIOs that are to be
2278		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2279		have GPIO-based defaults assigned to them as appropriate.
2280
2281		You should define these to the GPIO value as given directly to
2282		the generic GPIO functions.
2283
2284		CONFIG_SYS_I2C_INIT_BOARD
2285
2286		When a board is reset during an i2c bus transfer
2287		chips might think that the current transfer is still
2288		in progress. On some boards it is possible to access
2289		the i2c SCLK line directly, either by using the
2290		processor pin as a GPIO or by having a second pin
2291		connected to the bus. If this option is defined a
2292		custom i2c_init_board() routine in boards/xxx/board.c
2293		is run early in the boot sequence.
2294
2295		CONFIG_SYS_I2C_BOARD_LATE_INIT
2296
2297		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2298		defined a custom i2c_board_late_init() routine in
2299		boards/xxx/board.c is run AFTER the operations in i2c_init()
2300		is completed. This callpoint can be used to unreset i2c bus
2301		using CPU i2c controller register accesses for CPUs whose i2c
2302		controller provide such a method. It is called at the end of
2303		i2c_init() to allow i2c_init operations to setup the i2c bus
2304		controller on the CPU (e.g. setting bus speed & slave address).
2305
2306		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2307
2308		This option enables configuration of bi_iic_fast[] flags
2309		in u-boot bd_info structure based on u-boot environment
2310		variable "i2cfast". (see also i2cfast)
2311
2312		CONFIG_I2C_MULTI_BUS
2313
2314		This option allows the use of multiple I2C buses, each of which
2315		must have a controller.	 At any point in time, only one bus is
2316		active.	 To switch to a different bus, use the 'i2c dev' command.
2317		Note that bus numbering is zero-based.
2318
2319		CONFIG_SYS_I2C_NOPROBES
2320
2321		This option specifies a list of I2C devices that will be skipped
2322		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2323		is set, specify a list of bus-device pairs.  Otherwise, specify
2324		a 1D array of device addresses
2325
2326		e.g.
2327			#undef	CONFIG_I2C_MULTI_BUS
2328			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2329
2330		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2331
2332			#define CONFIG_I2C_MULTI_BUS
2333			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2334
2335		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2336
2337		CONFIG_SYS_SPD_BUS_NUM
2338
2339		If defined, then this indicates the I2C bus number for DDR SPD.
2340		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2341
2342		CONFIG_SYS_RTC_BUS_NUM
2343
2344		If defined, then this indicates the I2C bus number for the RTC.
2345		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2346
2347		CONFIG_SYS_DTT_BUS_NUM
2348
2349		If defined, then this indicates the I2C bus number for the DTT.
2350		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2351
2352		CONFIG_SYS_I2C_DTT_ADDR:
2353
2354		If defined, specifies the I2C address of the DTT device.
2355		If not defined, then U-Boot uses predefined value for
2356		specified DTT device.
2357
2358		CONFIG_SOFT_I2C_READ_REPEATED_START
2359
2360		defining this will force the i2c_read() function in
2361		the soft_i2c driver to perform an I2C repeated start
2362		between writing the address pointer and reading the
2363		data.  If this define is omitted the default behaviour
2364		of doing a stop-start sequence will be used.  Most I2C
2365		devices can use either method, but some require one or
2366		the other.
2367
2368- SPI Support:	CONFIG_SPI
2369
2370		Enables SPI driver (so far only tested with
2371		SPI EEPROM, also an instance works with Crystal A/D and
2372		D/As on the SACSng board)
2373
2374		CONFIG_SH_SPI
2375
2376		Enables the driver for SPI controller on SuperH. Currently
2377		only SH7757 is supported.
2378
2379		CONFIG_SPI_X
2380
2381		Enables extended (16-bit) SPI EEPROM addressing.
2382		(symmetrical to CONFIG_I2C_X)
2383
2384		CONFIG_SOFT_SPI
2385
2386		Enables a software (bit-bang) SPI driver rather than
2387		using hardware support. This is a general purpose
2388		driver that only requires three general I/O port pins
2389		(two outputs, one input) to function. If this is
2390		defined, the board configuration must define several
2391		SPI configuration items (port pins to use, etc). For
2392		an example, see include/configs/sacsng.h.
2393
2394		CONFIG_HARD_SPI
2395
2396		Enables a hardware SPI driver for general-purpose reads
2397		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2398		must define a list of chip-select function pointers.
2399		Currently supported on some MPC8xxx processors.	 For an
2400		example, see include/configs/mpc8349emds.h.
2401
2402		CONFIG_MXC_SPI
2403
2404		Enables the driver for the SPI controllers on i.MX and MXC
2405		SoCs. Currently i.MX31/35/51 are supported.
2406
2407- FPGA Support: CONFIG_FPGA
2408
2409		Enables FPGA subsystem.
2410
2411		CONFIG_FPGA_<vendor>
2412
2413		Enables support for specific chip vendors.
2414		(ALTERA, XILINX)
2415
2416		CONFIG_FPGA_<family>
2417
2418		Enables support for FPGA family.
2419		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2420
2421		CONFIG_FPGA_COUNT
2422
2423		Specify the number of FPGA devices to support.
2424
2425		CONFIG_SYS_FPGA_PROG_FEEDBACK
2426
2427		Enable printing of hash marks during FPGA configuration.
2428
2429		CONFIG_SYS_FPGA_CHECK_BUSY
2430
2431		Enable checks on FPGA configuration interface busy
2432		status by the configuration function. This option
2433		will require a board or device specific function to
2434		be written.
2435
2436		CONFIG_FPGA_DELAY
2437
2438		If defined, a function that provides delays in the FPGA
2439		configuration driver.
2440
2441		CONFIG_SYS_FPGA_CHECK_CTRLC
2442		Allow Control-C to interrupt FPGA configuration
2443
2444		CONFIG_SYS_FPGA_CHECK_ERROR
2445
2446		Check for configuration errors during FPGA bitfile
2447		loading. For example, abort during Virtex II
2448		configuration if the INIT_B line goes low (which
2449		indicated a CRC error).
2450
2451		CONFIG_SYS_FPGA_WAIT_INIT
2452
2453		Maximum time to wait for the INIT_B line to deassert
2454		after PROB_B has been deasserted during a Virtex II
2455		FPGA configuration sequence. The default time is 500
2456		ms.
2457
2458		CONFIG_SYS_FPGA_WAIT_BUSY
2459
2460		Maximum time to wait for BUSY to deassert during
2461		Virtex II FPGA configuration. The default is 5 ms.
2462
2463		CONFIG_SYS_FPGA_WAIT_CONFIG
2464
2465		Time to wait after FPGA configuration. The default is
2466		200 ms.
2467
2468- Configuration Management:
2469		CONFIG_IDENT_STRING
2470
2471		If defined, this string will be added to the U-Boot
2472		version information (U_BOOT_VERSION)
2473
2474- Vendor Parameter Protection:
2475
2476		U-Boot considers the values of the environment
2477		variables "serial#" (Board Serial Number) and
2478		"ethaddr" (Ethernet Address) to be parameters that
2479		are set once by the board vendor / manufacturer, and
2480		protects these variables from casual modification by
2481		the user. Once set, these variables are read-only,
2482		and write or delete attempts are rejected. You can
2483		change this behaviour:
2484
2485		If CONFIG_ENV_OVERWRITE is #defined in your config
2486		file, the write protection for vendor parameters is
2487		completely disabled. Anybody can change or delete
2488		these parameters.
2489
2490		Alternatively, if you #define _both_ CONFIG_ETHADDR
2491		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2492		Ethernet address is installed in the environment,
2493		which can be changed exactly ONCE by the user. [The
2494		serial# is unaffected by this, i. e. it remains
2495		read-only.]
2496
2497		The same can be accomplished in a more flexible way
2498		for any variable by configuring the type of access
2499		to allow for those variables in the ".flags" variable
2500		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2501
2502- Protected RAM:
2503		CONFIG_PRAM
2504
2505		Define this variable to enable the reservation of
2506		"protected RAM", i. e. RAM which is not overwritten
2507		by U-Boot. Define CONFIG_PRAM to hold the number of
2508		kB you want to reserve for pRAM. You can overwrite
2509		this default value by defining an environment
2510		variable "pram" to the number of kB you want to
2511		reserve. Note that the board info structure will
2512		still show the full amount of RAM. If pRAM is
2513		reserved, a new environment variable "mem" will
2514		automatically be defined to hold the amount of
2515		remaining RAM in a form that can be passed as boot
2516		argument to Linux, for instance like that:
2517
2518			setenv bootargs ... mem=\${mem}
2519			saveenv
2520
2521		This way you can tell Linux not to use this memory,
2522		either, which results in a memory region that will
2523		not be affected by reboots.
2524
2525		*WARNING* If your board configuration uses automatic
2526		detection of the RAM size, you must make sure that
2527		this memory test is non-destructive. So far, the
2528		following board configurations are known to be
2529		"pRAM-clean":
2530
2531			IVMS8, IVML24, SPD8xx, TQM8xxL,
2532			HERMES, IP860, RPXlite, LWMON,
2533			FLAGADM, TQM8260
2534
2535- Access to physical memory region (> 4GB)
2536		Some basic support is provided for operations on memory not
2537		normally accessible to U-Boot - e.g. some architectures
2538		support access to more than 4GB of memory on 32-bit
2539		machines using physical address extension or similar.
2540		Define CONFIG_PHYSMEM to access this basic support, which
2541		currently only supports clearing the memory.
2542
2543- Error Recovery:
2544		CONFIG_PANIC_HANG
2545
2546		Define this variable to stop the system in case of a
2547		fatal error, so that you have to reset it manually.
2548		This is probably NOT a good idea for an embedded
2549		system where you want the system to reboot
2550		automatically as fast as possible, but it may be
2551		useful during development since you can try to debug
2552		the conditions that lead to the situation.
2553
2554		CONFIG_NET_RETRY_COUNT
2555
2556		This variable defines the number of retries for
2557		network operations like ARP, RARP, TFTP, or BOOTP
2558		before giving up the operation. If not defined, a
2559		default value of 5 is used.
2560
2561		CONFIG_ARP_TIMEOUT
2562
2563		Timeout waiting for an ARP reply in milliseconds.
2564
2565		CONFIG_NFS_TIMEOUT
2566
2567		Timeout in milliseconds used in NFS protocol.
2568		If you encounter "ERROR: Cannot umount" in nfs command,
2569		try longer timeout such as
2570		#define CONFIG_NFS_TIMEOUT 10000UL
2571
2572- Command Interpreter:
2573		CONFIG_AUTO_COMPLETE
2574
2575		Enable auto completion of commands using TAB.
2576
2577		Note that this feature has NOT been implemented yet
2578		for the "hush" shell.
2579
2580
2581		CONFIG_SYS_HUSH_PARSER
2582
2583		Define this variable to enable the "hush" shell (from
2584		Busybox) as command line interpreter, thus enabling
2585		powerful command line syntax like
2586		if...then...else...fi conditionals or `&&' and '||'
2587		constructs ("shell scripts").
2588
2589		If undefined, you get the old, much simpler behaviour
2590		with a somewhat smaller memory footprint.
2591
2592
2593		CONFIG_SYS_PROMPT_HUSH_PS2
2594
2595		This defines the secondary prompt string, which is
2596		printed when the command interpreter needs more input
2597		to complete a command. Usually "> ".
2598
2599	Note:
2600
2601		In the current implementation, the local variables
2602		space and global environment variables space are
2603		separated. Local variables are those you define by
2604		simply typing `name=value'. To access a local
2605		variable later on, you have write `$name' or
2606		`${name}'; to execute the contents of a variable
2607		directly type `$name' at the command prompt.
2608
2609		Global environment variables are those you use
2610		setenv/printenv to work with. To run a command stored
2611		in such a variable, you need to use the run command,
2612		and you must not use the '$' sign to access them.
2613
2614		To store commands and special characters in a
2615		variable, please use double quotation marks
2616		surrounding the whole text of the variable, instead
2617		of the backslashes before semicolons and special
2618		symbols.
2619
2620- Commandline Editing and History:
2621		CONFIG_CMDLINE_EDITING
2622
2623		Enable editing and History functions for interactive
2624		commandline input operations
2625
2626- Default Environment:
2627		CONFIG_EXTRA_ENV_SETTINGS
2628
2629		Define this to contain any number of null terminated
2630		strings (variable = value pairs) that will be part of
2631		the default environment compiled into the boot image.
2632
2633		For example, place something like this in your
2634		board's config file:
2635
2636		#define CONFIG_EXTRA_ENV_SETTINGS \
2637			"myvar1=value1\0" \
2638			"myvar2=value2\0"
2639
2640		Warning: This method is based on knowledge about the
2641		internal format how the environment is stored by the
2642		U-Boot code. This is NOT an official, exported
2643		interface! Although it is unlikely that this format
2644		will change soon, there is no guarantee either.
2645		You better know what you are doing here.
2646
2647		Note: overly (ab)use of the default environment is
2648		discouraged. Make sure to check other ways to preset
2649		the environment like the "source" command or the
2650		boot command first.
2651
2652		CONFIG_ENV_VARS_UBOOT_CONFIG
2653
2654		Define this in order to add variables describing the
2655		U-Boot build configuration to the default environment.
2656		These will be named arch, cpu, board, vendor, and soc.
2657
2658		Enabling this option will cause the following to be defined:
2659
2660		- CONFIG_SYS_ARCH
2661		- CONFIG_SYS_CPU
2662		- CONFIG_SYS_BOARD
2663		- CONFIG_SYS_VENDOR
2664		- CONFIG_SYS_SOC
2665
2666		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2667
2668		Define this in order to add variables describing certain
2669		run-time determined information about the hardware to the
2670		environment.  These will be named board_name, board_rev.
2671
2672		CONFIG_DELAY_ENVIRONMENT
2673
2674		Normally the environment is loaded when the board is
2675		intialised so that it is available to U-Boot. This inhibits
2676		that so that the environment is not available until
2677		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2678		this is instead controlled by the value of
2679		/config/load-environment.
2680
2681- DataFlash Support:
2682		CONFIG_HAS_DATAFLASH
2683
2684		Defining this option enables DataFlash features and
2685		allows to read/write in Dataflash via the standard
2686		commands cp, md...
2687
2688- Serial Flash support
2689		CONFIG_CMD_SF
2690
2691		Defining this option enables SPI flash commands
2692		'sf probe/read/write/erase/update'.
2693
2694		Usage requires an initial 'probe' to define the serial
2695		flash parameters, followed by read/write/erase/update
2696		commands.
2697
2698		The following defaults may be provided by the platform
2699		to handle the common case when only a single serial
2700		flash is present on the system.
2701
2702		CONFIG_SF_DEFAULT_BUS		Bus identifier
2703		CONFIG_SF_DEFAULT_CS		Chip-select
2704		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2705		CONFIG_SF_DEFAULT_SPEED		in Hz
2706
2707		CONFIG_CMD_SF_TEST
2708
2709		Define this option to include a destructive SPI flash
2710		test ('sf test').
2711
2712		CONFIG_SPI_FLASH_BAR		Ban/Extended Addr Reg
2713
2714		Define this option to use the Bank addr/Extended addr
2715		support on SPI flashes which has size > 16Mbytes.
2716
2717- SystemACE Support:
2718		CONFIG_SYSTEMACE
2719
2720		Adding this option adds support for Xilinx SystemACE
2721		chips attached via some sort of local bus. The address
2722		of the chip must also be defined in the
2723		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2724
2725		#define CONFIG_SYSTEMACE
2726		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2727
2728		When SystemACE support is added, the "ace" device type
2729		becomes available to the fat commands, i.e. fatls.
2730
2731- TFTP Fixed UDP Port:
2732		CONFIG_TFTP_PORT
2733
2734		If this is defined, the environment variable tftpsrcp
2735		is used to supply the TFTP UDP source port value.
2736		If tftpsrcp isn't defined, the normal pseudo-random port
2737		number generator is used.
2738
2739		Also, the environment variable tftpdstp is used to supply
2740		the TFTP UDP destination port value.  If tftpdstp isn't
2741		defined, the normal port 69 is used.
2742
2743		The purpose for tftpsrcp is to allow a TFTP server to
2744		blindly start the TFTP transfer using the pre-configured
2745		target IP address and UDP port. This has the effect of
2746		"punching through" the (Windows XP) firewall, allowing
2747		the remainder of the TFTP transfer to proceed normally.
2748		A better solution is to properly configure the firewall,
2749		but sometimes that is not allowed.
2750
2751- Hashing support:
2752		CONFIG_CMD_HASH
2753
2754		This enables a generic 'hash' command which can produce
2755		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
2756
2757		CONFIG_HASH_VERIFY
2758
2759		Enable the hash verify command (hash -v). This adds to code
2760		size a little.
2761
2762		CONFIG_SHA1 - support SHA1 hashing
2763		CONFIG_SHA256 - support SHA256 hashing
2764
2765		Note: There is also a sha1sum command, which should perhaps
2766		be deprecated in favour of 'hash sha1'.
2767
2768- Freescale i.MX specific commands:
2769		CONFIG_CMD_HDMIDETECT
2770		This enables 'hdmidet' command which returns true if an
2771		HDMI monitor is detected.  This command is i.MX 6 specific.
2772
2773		CONFIG_CMD_BMODE
2774		This enables the 'bmode' (bootmode) command for forcing
2775		a boot from specific media.
2776
2777		This is useful for forcing the ROM's usb downloader to
2778		activate upon a watchdog reset which is nice when iterating
2779		on U-Boot.  Using the reset button or running bmode normal
2780		will set it back to normal.  This command currently
2781		supports i.MX53 and i.MX6.
2782
2783- Signing support:
2784		CONFIG_RSA
2785
2786		This enables the RSA algorithm used for FIT image verification
2787		in U-Boot. See doc/uImage/signature for more information.
2788
2789		The signing part is build into mkimage regardless of this
2790		option.
2791
2792
2793- Show boot progress:
2794		CONFIG_SHOW_BOOT_PROGRESS
2795
2796		Defining this option allows to add some board-
2797		specific code (calling a user-provided function
2798		"show_boot_progress(int)") that enables you to show
2799		the system's boot progress on some display (for
2800		example, some LED's) on your board. At the moment,
2801		the following checkpoints are implemented:
2802
2803- Detailed boot stage timing
2804		CONFIG_BOOTSTAGE
2805		Define this option to get detailed timing of each stage
2806		of the boot process.
2807
2808		CONFIG_BOOTSTAGE_USER_COUNT
2809		This is the number of available user bootstage records.
2810		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
2811		a new ID will be allocated from this stash. If you exceed
2812		the limit, recording will stop.
2813
2814		CONFIG_BOOTSTAGE_REPORT
2815		Define this to print a report before boot, similar to this:
2816
2817		Timer summary in microseconds:
2818		       Mark    Elapsed  Stage
2819			  0          0  reset
2820		  3,575,678  3,575,678  board_init_f start
2821		  3,575,695         17  arch_cpu_init A9
2822		  3,575,777         82  arch_cpu_init done
2823		  3,659,598     83,821  board_init_r start
2824		  3,910,375    250,777  main_loop
2825		 29,916,167 26,005,792  bootm_start
2826		 30,361,327    445,160  start_kernel
2827
2828		CONFIG_CMD_BOOTSTAGE
2829		Add a 'bootstage' command which supports printing a report
2830		and un/stashing of bootstage data.
2831
2832		CONFIG_BOOTSTAGE_FDT
2833		Stash the bootstage information in the FDT. A root 'bootstage'
2834		node is created with each bootstage id as a child. Each child
2835		has a 'name' property and either 'mark' containing the
2836		mark time in microsecond, or 'accum' containing the
2837		accumulated time for that bootstage id in microseconds.
2838		For example:
2839
2840		bootstage {
2841			154 {
2842				name = "board_init_f";
2843				mark = <3575678>;
2844			};
2845			170 {
2846				name = "lcd";
2847				accum = <33482>;
2848			};
2849		};
2850
2851		Code in the Linux kernel can find this in /proc/devicetree.
2852
2853Legacy uImage format:
2854
2855  Arg	Where			When
2856    1	common/cmd_bootm.c	before attempting to boot an image
2857   -1	common/cmd_bootm.c	Image header has bad	 magic number
2858    2	common/cmd_bootm.c	Image header has correct magic number
2859   -2	common/cmd_bootm.c	Image header has bad	 checksum
2860    3	common/cmd_bootm.c	Image header has correct checksum
2861   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2862    4	common/cmd_bootm.c	Image data   has correct checksum
2863   -4	common/cmd_bootm.c	Image is for unsupported architecture
2864    5	common/cmd_bootm.c	Architecture check OK
2865   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2866    6	common/cmd_bootm.c	Image Type check OK
2867   -6	common/cmd_bootm.c	gunzip uncompression error
2868   -7	common/cmd_bootm.c	Unimplemented compression type
2869    7	common/cmd_bootm.c	Uncompression OK
2870    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2871   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2872
2873    9	common/image.c		Start initial ramdisk verification
2874  -10	common/image.c		Ramdisk header has bad	   magic number
2875  -11	common/image.c		Ramdisk header has bad	   checksum
2876   10	common/image.c		Ramdisk header is OK
2877  -12	common/image.c		Ramdisk data   has bad	   checksum
2878   11	common/image.c		Ramdisk data   has correct checksum
2879   12	common/image.c		Ramdisk verification complete, start loading
2880  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2881   13	common/image.c		Start multifile image verification
2882   14	common/image.c		No initial ramdisk, no multifile, continue.
2883
2884   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2885
2886  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2887  -31	post/post.c		POST test failed, detected by post_output_backlog()
2888  -32	post/post.c		POST test failed, detected by post_run_single()
2889
2890   34	common/cmd_doc.c	before loading a Image from a DOC device
2891  -35	common/cmd_doc.c	Bad usage of "doc" command
2892   35	common/cmd_doc.c	correct usage of "doc" command
2893  -36	common/cmd_doc.c	No boot device
2894   36	common/cmd_doc.c	correct boot device
2895  -37	common/cmd_doc.c	Unknown Chip ID on boot device
2896   37	common/cmd_doc.c	correct chip ID found, device available
2897  -38	common/cmd_doc.c	Read Error on boot device
2898   38	common/cmd_doc.c	reading Image header from DOC device OK
2899  -39	common/cmd_doc.c	Image header has bad magic number
2900   39	common/cmd_doc.c	Image header has correct magic number
2901  -40	common/cmd_doc.c	Error reading Image from DOC device
2902   40	common/cmd_doc.c	Image header has correct magic number
2903   41	common/cmd_ide.c	before loading a Image from a IDE device
2904  -42	common/cmd_ide.c	Bad usage of "ide" command
2905   42	common/cmd_ide.c	correct usage of "ide" command
2906  -43	common/cmd_ide.c	No boot device
2907   43	common/cmd_ide.c	boot device found
2908  -44	common/cmd_ide.c	Device not available
2909   44	common/cmd_ide.c	Device available
2910  -45	common/cmd_ide.c	wrong partition selected
2911   45	common/cmd_ide.c	partition selected
2912  -46	common/cmd_ide.c	Unknown partition table
2913   46	common/cmd_ide.c	valid partition table found
2914  -47	common/cmd_ide.c	Invalid partition type
2915   47	common/cmd_ide.c	correct partition type
2916  -48	common/cmd_ide.c	Error reading Image Header on boot device
2917   48	common/cmd_ide.c	reading Image Header from IDE device OK
2918  -49	common/cmd_ide.c	Image header has bad magic number
2919   49	common/cmd_ide.c	Image header has correct magic number
2920  -50	common/cmd_ide.c	Image header has bad	 checksum
2921   50	common/cmd_ide.c	Image header has correct checksum
2922  -51	common/cmd_ide.c	Error reading Image from IDE device
2923   51	common/cmd_ide.c	reading Image from IDE device OK
2924   52	common/cmd_nand.c	before loading a Image from a NAND device
2925  -53	common/cmd_nand.c	Bad usage of "nand" command
2926   53	common/cmd_nand.c	correct usage of "nand" command
2927  -54	common/cmd_nand.c	No boot device
2928   54	common/cmd_nand.c	boot device found
2929  -55	common/cmd_nand.c	Unknown Chip ID on boot device
2930   55	common/cmd_nand.c	correct chip ID found, device available
2931  -56	common/cmd_nand.c	Error reading Image Header on boot device
2932   56	common/cmd_nand.c	reading Image Header from NAND device OK
2933  -57	common/cmd_nand.c	Image header has bad magic number
2934   57	common/cmd_nand.c	Image header has correct magic number
2935  -58	common/cmd_nand.c	Error reading Image from NAND device
2936   58	common/cmd_nand.c	reading Image from NAND device OK
2937
2938  -60	common/env_common.c	Environment has a bad CRC, using default
2939
2940   64	net/eth.c		starting with Ethernet configuration.
2941  -64	net/eth.c		no Ethernet found.
2942   65	net/eth.c		Ethernet found.
2943
2944  -80	common/cmd_net.c	usage wrong
2945   80	common/cmd_net.c	before calling NetLoop()
2946  -81	common/cmd_net.c	some error in NetLoop() occurred
2947   81	common/cmd_net.c	NetLoop() back without error
2948  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
2949   82	common/cmd_net.c	trying automatic boot
2950   83	common/cmd_net.c	running "source" command
2951  -83	common/cmd_net.c	some error in automatic boot or "source" command
2952   84	common/cmd_net.c	end without errors
2953
2954FIT uImage format:
2955
2956  Arg	Where			When
2957  100	common/cmd_bootm.c	Kernel FIT Image has correct format
2958 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
2959  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
2960 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
2961  102	common/cmd_bootm.c	Kernel unit name specified
2962 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
2963  103	common/cmd_bootm.c	Found configuration node
2964  104	common/cmd_bootm.c	Got kernel subimage node offset
2965 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
2966  105	common/cmd_bootm.c	Kernel subimage hash verification OK
2967 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
2968  106	common/cmd_bootm.c	Architecture check OK
2969 -106	common/cmd_bootm.c	Kernel subimage has wrong type
2970  107	common/cmd_bootm.c	Kernel subimage type OK
2971 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
2972  108	common/cmd_bootm.c	Got kernel subimage data/size
2973 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
2974 -109	common/cmd_bootm.c	Can't get kernel subimage type
2975 -110	common/cmd_bootm.c	Can't get kernel subimage comp
2976 -111	common/cmd_bootm.c	Can't get kernel subimage os
2977 -112	common/cmd_bootm.c	Can't get kernel subimage load address
2978 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
2979
2980  120	common/image.c		Start initial ramdisk verification
2981 -120	common/image.c		Ramdisk FIT image has incorrect format
2982  121	common/image.c		Ramdisk FIT image has correct format
2983  122	common/image.c		No ramdisk subimage unit name, using configuration
2984 -122	common/image.c		Can't get configuration for ramdisk subimage
2985  123	common/image.c		Ramdisk unit name specified
2986 -124	common/image.c		Can't get ramdisk subimage node offset
2987  125	common/image.c		Got ramdisk subimage node offset
2988 -125	common/image.c		Ramdisk subimage hash verification failed
2989  126	common/image.c		Ramdisk subimage hash verification OK
2990 -126	common/image.c		Ramdisk subimage for unsupported architecture
2991  127	common/image.c		Architecture check OK
2992 -127	common/image.c		Can't get ramdisk subimage data/size
2993  128	common/image.c		Got ramdisk subimage data/size
2994  129	common/image.c		Can't get ramdisk load address
2995 -129	common/image.c		Got ramdisk load address
2996
2997 -130	common/cmd_doc.c	Incorrect FIT image format
2998  131	common/cmd_doc.c	FIT image format OK
2999
3000 -140	common/cmd_ide.c	Incorrect FIT image format
3001  141	common/cmd_ide.c	FIT image format OK
3002
3003 -150	common/cmd_nand.c	Incorrect FIT image format
3004  151	common/cmd_nand.c	FIT image format OK
3005
3006- FIT image support:
3007		CONFIG_FIT
3008		Enable support for the FIT uImage format.
3009
3010		CONFIG_FIT_BEST_MATCH
3011		When no configuration is explicitly selected, default to the
3012		one whose fdt's compatibility field best matches that of
3013		U-Boot itself. A match is considered "best" if it matches the
3014		most specific compatibility entry of U-Boot's fdt's root node.
3015		The order of entries in the configuration's fdt is ignored.
3016
3017		CONFIG_FIT_SIGNATURE
3018		This option enables signature verification of FIT uImages,
3019		using a hash signed and verified using RSA. See
3020		doc/uImage.FIT/signature.txt for more details.
3021
3022- Standalone program support:
3023		CONFIG_STANDALONE_LOAD_ADDR
3024
3025		This option defines a board specific value for the
3026		address where standalone program gets loaded, thus
3027		overwriting the architecture dependent default
3028		settings.
3029
3030- Frame Buffer Address:
3031		CONFIG_FB_ADDR
3032
3033		Define CONFIG_FB_ADDR if you want to use specific
3034		address for frame buffer.  This is typically the case
3035		when using a graphics controller has separate video
3036		memory.  U-Boot will then place the frame buffer at
3037		the given address instead of dynamically reserving it
3038		in system RAM by calling lcd_setmem(), which grabs
3039		the memory for the frame buffer depending on the
3040		configured panel size.
3041
3042		Please see board_init_f function.
3043
3044- Automatic software updates via TFTP server
3045		CONFIG_UPDATE_TFTP
3046		CONFIG_UPDATE_TFTP_CNT_MAX
3047		CONFIG_UPDATE_TFTP_MSEC_MAX
3048
3049		These options enable and control the auto-update feature;
3050		for a more detailed description refer to doc/README.update.
3051
3052- MTD Support (mtdparts command, UBI support)
3053		CONFIG_MTD_DEVICE
3054
3055		Adds the MTD device infrastructure from the Linux kernel.
3056		Needed for mtdparts command support.
3057
3058		CONFIG_MTD_PARTITIONS
3059
3060		Adds the MTD partitioning infrastructure from the Linux
3061		kernel. Needed for UBI support.
3062
3063- UBI support
3064		CONFIG_CMD_UBI
3065
3066		Adds commands for interacting with MTD partitions formatted
3067		with the UBI flash translation layer
3068
3069		Requires also defining CONFIG_RBTREE
3070
3071		CONFIG_UBI_SILENCE_MSG
3072
3073		Make the verbose messages from UBI stop printing.  This leaves
3074		warnings and errors enabled.
3075
3076- UBIFS support
3077		CONFIG_CMD_UBIFS
3078
3079		Adds commands for interacting with UBI volumes formatted as
3080		UBIFS.  UBIFS is read-only in u-boot.
3081
3082		Requires UBI support as well as CONFIG_LZO
3083
3084		CONFIG_UBIFS_SILENCE_MSG
3085
3086		Make the verbose messages from UBIFS stop printing.  This leaves
3087		warnings and errors enabled.
3088
3089- SPL framework
3090		CONFIG_SPL
3091		Enable building of SPL globally.
3092
3093		CONFIG_SPL_LDSCRIPT
3094		LDSCRIPT for linking the SPL binary.
3095
3096		CONFIG_SPL_MAX_FOOTPRINT
3097		Maximum size in memory allocated to the SPL, BSS included.
3098		When defined, the linker checks that the actual memory
3099		used by SPL from _start to __bss_end does not exceed it.
3100		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3101		must not be both defined at the same time.
3102
3103		CONFIG_SPL_MAX_SIZE
3104		Maximum size of the SPL image (text, data, rodata, and
3105		linker lists sections), BSS excluded.
3106		When defined, the linker checks that the actual size does
3107		not exceed it.
3108
3109		CONFIG_SPL_TEXT_BASE
3110		TEXT_BASE for linking the SPL binary.
3111
3112		CONFIG_SPL_RELOC_TEXT_BASE
3113		Address to relocate to.  If unspecified, this is equal to
3114		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3115
3116		CONFIG_SPL_BSS_START_ADDR
3117		Link address for the BSS within the SPL binary.
3118
3119		CONFIG_SPL_BSS_MAX_SIZE
3120		Maximum size in memory allocated to the SPL BSS.
3121		When defined, the linker checks that the actual memory used
3122		by SPL from __bss_start to __bss_end does not exceed it.
3123		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3124		must not be both defined at the same time.
3125
3126		CONFIG_SPL_STACK
3127		Adress of the start of the stack SPL will use
3128
3129		CONFIG_SPL_RELOC_STACK
3130		Adress of the start of the stack SPL will use after
3131		relocation.  If unspecified, this is equal to
3132		CONFIG_SPL_STACK.
3133
3134		CONFIG_SYS_SPL_MALLOC_START
3135		Starting address of the malloc pool used in SPL.
3136
3137		CONFIG_SYS_SPL_MALLOC_SIZE
3138		The size of the malloc pool used in SPL.
3139
3140		CONFIG_SPL_FRAMEWORK
3141		Enable the SPL framework under common/.  This framework
3142		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3143		NAND loading of the Linux Kernel.
3144
3145		CONFIG_SPL_DISPLAY_PRINT
3146		For ARM, enable an optional function to print more information
3147		about the running system.
3148
3149		CONFIG_SPL_INIT_MINIMAL
3150		Arch init code should be built for a very small image
3151
3152		CONFIG_SPL_LIBCOMMON_SUPPORT
3153		Support for common/libcommon.o in SPL binary
3154
3155		CONFIG_SPL_LIBDISK_SUPPORT
3156		Support for disk/libdisk.o in SPL binary
3157
3158		CONFIG_SPL_I2C_SUPPORT
3159		Support for drivers/i2c/libi2c.o in SPL binary
3160
3161		CONFIG_SPL_GPIO_SUPPORT
3162		Support for drivers/gpio/libgpio.o in SPL binary
3163
3164		CONFIG_SPL_MMC_SUPPORT
3165		Support for drivers/mmc/libmmc.o in SPL binary
3166
3167		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3168		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3169		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
3170		Address, size and partition on the MMC to load U-Boot from
3171		when the MMC is being used in raw mode.
3172
3173		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3174		Sector to load kernel uImage from when MMC is being
3175		used in raw mode (for Falcon mode)
3176
3177		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3178		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3179		Sector and number of sectors to load kernel argument
3180		parameters from when MMC is being used in raw mode
3181		(for falcon mode)
3182
3183		CONFIG_SPL_FAT_SUPPORT
3184		Support for fs/fat/libfat.o in SPL binary
3185
3186		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
3187		Filename to read to load U-Boot when reading from FAT
3188
3189		CONFIG_SPL_FAT_LOAD_KERNEL_NAME
3190		Filename to read to load kernel uImage when reading
3191		from FAT (for Falcon mode)
3192
3193		CONFIG_SPL_FAT_LOAD_ARGS_NAME
3194		Filename to read to load kernel argument parameters
3195		when reading from FAT (for Falcon mode)
3196
3197		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3198		Set this for NAND SPL on PPC mpc83xx targets, so that
3199		start.S waits for the rest of the SPL to load before
3200		continuing (the hardware starts execution after just
3201		loading the first page rather than the full 4K).
3202
3203		CONFIG_SPL_NAND_BASE
3204		Include nand_base.c in the SPL.  Requires
3205		CONFIG_SPL_NAND_DRIVERS.
3206
3207		CONFIG_SPL_NAND_DRIVERS
3208		SPL uses normal NAND drivers, not minimal drivers.
3209
3210		CONFIG_SPL_NAND_ECC
3211		Include standard software ECC in the SPL
3212
3213		CONFIG_SPL_NAND_SIMPLE
3214		Support for NAND boot using simple NAND drivers that
3215		expose the cmd_ctrl() interface.
3216
3217		CONFIG_SPL_MPC8XXX_INIT_DDR_SUPPORT
3218		Set for the SPL on PPC mpc8xxx targets, support for
3219		drivers/ddr/fsl/libddr.o in SPL binary.
3220
3221		CONFIG_SPL_COMMON_INIT_DDR
3222		Set for common ddr init with serial presence detect in
3223		SPL binary.
3224
3225		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3226		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3227		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3228		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3229		CONFIG_SYS_NAND_ECCBYTES
3230		Defines the size and behavior of the NAND that SPL uses
3231		to read U-Boot
3232
3233		CONFIG_SYS_NAND_U_BOOT_OFFS
3234		Location in NAND to read U-Boot from
3235
3236		CONFIG_SYS_NAND_U_BOOT_DST
3237		Location in memory to load U-Boot to
3238
3239		CONFIG_SYS_NAND_U_BOOT_SIZE
3240		Size of image to load
3241
3242		CONFIG_SYS_NAND_U_BOOT_START
3243		Entry point in loaded image to jump to
3244
3245		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3246		Define this if you need to first read the OOB and then the
3247		data. This is used for example on davinci plattforms.
3248
3249		CONFIG_SPL_OMAP3_ID_NAND
3250		Support for an OMAP3-specific set of functions to return the
3251		ID and MFR of the first attached NAND chip, if present.
3252
3253		CONFIG_SPL_SERIAL_SUPPORT
3254		Support for drivers/serial/libserial.o in SPL binary
3255
3256		CONFIG_SPL_SPI_FLASH_SUPPORT
3257		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
3258
3259		CONFIG_SPL_SPI_SUPPORT
3260		Support for drivers/spi/libspi.o in SPL binary
3261
3262		CONFIG_SPL_RAM_DEVICE
3263		Support for running image already present in ram, in SPL binary
3264
3265		CONFIG_SPL_LIBGENERIC_SUPPORT
3266		Support for lib/libgeneric.o in SPL binary
3267
3268		CONFIG_SPL_ENV_SUPPORT
3269		Support for the environment operating in SPL binary
3270
3271		CONFIG_SPL_NET_SUPPORT
3272		Support for the net/libnet.o in SPL binary.
3273		It conflicts with SPL env from storage medium specified by
3274		CONFIG_ENV_IS_xxx but CONFIG_ENV_IS_NOWHERE
3275
3276		CONFIG_SPL_PAD_TO
3277		Image offset to which the SPL should be padded before appending
3278		the SPL payload. By default, this is defined as
3279		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3280		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3281		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3282
3283		CONFIG_SPL_TARGET
3284		Final target image containing SPL and payload.  Some SPLs
3285		use an arch-specific makefile fragment instead, for
3286		example if more than one image needs to be produced.
3287
3288		CONFIG_FIT_SPL_PRINT
3289		Printing information about a FIT image adds quite a bit of
3290		code to SPL. So this is normally disabled in SPL. Use this
3291		option to re-enable it. This will affect the output of the
3292		bootm command when booting a FIT image.
3293
3294- TPL framework
3295		CONFIG_TPL
3296		Enable building of TPL globally.
3297
3298		CONFIG_TPL_PAD_TO
3299		Image offset to which the TPL should be padded before appending
3300		the TPL payload. By default, this is defined as
3301		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3302		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3303		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3304
3305Modem Support:
3306--------------
3307
3308[so far only for SMDK2400 boards]
3309
3310- Modem support enable:
3311		CONFIG_MODEM_SUPPORT
3312
3313- RTS/CTS Flow control enable:
3314		CONFIG_HWFLOW
3315
3316- Modem debug support:
3317		CONFIG_MODEM_SUPPORT_DEBUG
3318
3319		Enables debugging stuff (char screen[1024], dbg())
3320		for modem support. Useful only with BDI2000.
3321
3322- Interrupt support (PPC):
3323
3324		There are common interrupt_init() and timer_interrupt()
3325		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3326		for CPU specific initialization. interrupt_init_cpu()
3327		should set decrementer_count to appropriate value. If
3328		CPU resets decrementer automatically after interrupt
3329		(ppc4xx) it should set decrementer_count to zero.
3330		timer_interrupt() calls timer_interrupt_cpu() for CPU
3331		specific handling. If board has watchdog / status_led
3332		/ other_activity_monitor it works automatically from
3333		general timer_interrupt().
3334
3335- General:
3336
3337		In the target system modem support is enabled when a
3338		specific key (key combination) is pressed during
3339		power-on. Otherwise U-Boot will boot normally
3340		(autoboot). The key_pressed() function is called from
3341		board_init(). Currently key_pressed() is a dummy
3342		function, returning 1 and thus enabling modem
3343		initialization.
3344
3345		If there are no modem init strings in the
3346		environment, U-Boot proceed to autoboot; the
3347		previous output (banner, info printfs) will be
3348		suppressed, though.
3349
3350		See also: doc/README.Modem
3351
3352Board initialization settings:
3353------------------------------
3354
3355During Initialization u-boot calls a number of board specific functions
3356to allow the preparation of board specific prerequisites, e.g. pin setup
3357before drivers are initialized. To enable these callbacks the
3358following configuration macros have to be defined. Currently this is
3359architecture specific, so please check arch/your_architecture/lib/board.c
3360typically in board_init_f() and board_init_r().
3361
3362- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3363- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3364- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3365- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3366
3367Configuration Settings:
3368-----------------------
3369
3370- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3371		undefine this when you're short of memory.
3372
3373- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3374		width of the commands listed in the 'help' command output.
3375
3376- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3377		prompt for user input.
3378
3379- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3380
3381- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3382
3383- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3384
3385- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3386		the application (usually a Linux kernel) when it is
3387		booted
3388
3389- CONFIG_SYS_BAUDRATE_TABLE:
3390		List of legal baudrate settings for this board.
3391
3392- CONFIG_SYS_CONSOLE_INFO_QUIET
3393		Suppress display of console information at boot.
3394
3395- CONFIG_SYS_CONSOLE_IS_IN_ENV
3396		If the board specific function
3397			extern int overwrite_console (void);
3398		returns 1, the stdin, stderr and stdout are switched to the
3399		serial port, else the settings in the environment are used.
3400
3401- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3402		Enable the call to overwrite_console().
3403
3404- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3405		Enable overwrite of previous console environment settings.
3406
3407- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3408		Begin and End addresses of the area used by the
3409		simple memory test.
3410
3411- CONFIG_SYS_ALT_MEMTEST:
3412		Enable an alternate, more extensive memory test.
3413
3414- CONFIG_SYS_MEMTEST_SCRATCH:
3415		Scratch address used by the alternate memory test
3416		You only need to set this if address zero isn't writeable
3417
3418- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
3419		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3420		this specified memory area will get subtracted from the top
3421		(end) of RAM and won't get "touched" at all by U-Boot. By
3422		fixing up gd->ram_size the Linux kernel should gets passed
3423		the now "corrected" memory size and won't touch it either.
3424		This should work for arch/ppc and arch/powerpc. Only Linux
3425		board ports in arch/powerpc with bootwrapper support that
3426		recalculate the memory size from the SDRAM controller setup
3427		will have to get fixed in Linux additionally.
3428
3429		This option can be used as a workaround for the 440EPx/GRx
3430		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3431		be touched.
3432
3433		WARNING: Please make sure that this value is a multiple of
3434		the Linux page size (normally 4k). If this is not the case,
3435		then the end address of the Linux memory will be located at a
3436		non page size aligned address and this could cause major
3437		problems.
3438
3439- CONFIG_SYS_LOADS_BAUD_CHANGE:
3440		Enable temporary baudrate change while serial download
3441
3442- CONFIG_SYS_SDRAM_BASE:
3443		Physical start address of SDRAM. _Must_ be 0 here.
3444
3445- CONFIG_SYS_MBIO_BASE:
3446		Physical start address of Motherboard I/O (if using a
3447		Cogent motherboard)
3448
3449- CONFIG_SYS_FLASH_BASE:
3450		Physical start address of Flash memory.
3451
3452- CONFIG_SYS_MONITOR_BASE:
3453		Physical start address of boot monitor code (set by
3454		make config files to be same as the text base address
3455		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3456		CONFIG_SYS_FLASH_BASE when booting from flash.
3457
3458- CONFIG_SYS_MONITOR_LEN:
3459		Size of memory reserved for monitor code, used to
3460		determine _at_compile_time_ (!) if the environment is
3461		embedded within the U-Boot image, or in a separate
3462		flash sector.
3463
3464- CONFIG_SYS_MALLOC_LEN:
3465		Size of DRAM reserved for malloc() use.
3466
3467- CONFIG_SYS_BOOTM_LEN:
3468		Normally compressed uImages are limited to an
3469		uncompressed size of 8 MBytes. If this is not enough,
3470		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3471		to adjust this setting to your needs.
3472
3473- CONFIG_SYS_BOOTMAPSZ:
3474		Maximum size of memory mapped by the startup code of
3475		the Linux kernel; all data that must be processed by
3476		the Linux kernel (bd_info, boot arguments, FDT blob if
3477		used) must be put below this limit, unless "bootm_low"
3478		environment variable is defined and non-zero. In such case
3479		all data for the Linux kernel must be between "bootm_low"
3480		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3481		variable "bootm_mapsize" will override the value of
3482		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3483		then the value in "bootm_size" will be used instead.
3484
3485- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3486		Enable initrd_high functionality.  If defined then the
3487		initrd_high feature is enabled and the bootm ramdisk subcommand
3488		is enabled.
3489
3490- CONFIG_SYS_BOOT_GET_CMDLINE:
3491		Enables allocating and saving kernel cmdline in space between
3492		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3493
3494- CONFIG_SYS_BOOT_GET_KBD:
3495		Enables allocating and saving a kernel copy of the bd_info in
3496		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3497
3498- CONFIG_SYS_MAX_FLASH_BANKS:
3499		Max number of Flash memory banks
3500
3501- CONFIG_SYS_MAX_FLASH_SECT:
3502		Max number of sectors on a Flash chip
3503
3504- CONFIG_SYS_FLASH_ERASE_TOUT:
3505		Timeout for Flash erase operations (in ms)
3506
3507- CONFIG_SYS_FLASH_WRITE_TOUT:
3508		Timeout for Flash write operations (in ms)
3509
3510- CONFIG_SYS_FLASH_LOCK_TOUT
3511		Timeout for Flash set sector lock bit operation (in ms)
3512
3513- CONFIG_SYS_FLASH_UNLOCK_TOUT
3514		Timeout for Flash clear lock bits operation (in ms)
3515
3516- CONFIG_SYS_FLASH_PROTECTION
3517		If defined, hardware flash sectors protection is used
3518		instead of U-Boot software protection.
3519
3520- CONFIG_SYS_DIRECT_FLASH_TFTP:
3521
3522		Enable TFTP transfers directly to flash memory;
3523		without this option such a download has to be
3524		performed in two steps: (1) download to RAM, and (2)
3525		copy from RAM to flash.
3526
3527		The two-step approach is usually more reliable, since
3528		you can check if the download worked before you erase
3529		the flash, but in some situations (when system RAM is
3530		too limited to allow for a temporary copy of the
3531		downloaded image) this option may be very useful.
3532
3533- CONFIG_SYS_FLASH_CFI:
3534		Define if the flash driver uses extra elements in the
3535		common flash structure for storing flash geometry.
3536
3537- CONFIG_FLASH_CFI_DRIVER
3538		This option also enables the building of the cfi_flash driver
3539		in the drivers directory
3540
3541- CONFIG_FLASH_CFI_MTD
3542		This option enables the building of the cfi_mtd driver
3543		in the drivers directory. The driver exports CFI flash
3544		to the MTD layer.
3545
3546- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3547		Use buffered writes to flash.
3548
3549- CONFIG_FLASH_SPANSION_S29WS_N
3550		s29ws-n MirrorBit flash has non-standard addresses for buffered
3551		write commands.
3552
3553- CONFIG_SYS_FLASH_QUIET_TEST
3554		If this option is defined, the common CFI flash doesn't
3555		print it's warning upon not recognized FLASH banks. This
3556		is useful, if some of the configured banks are only
3557		optionally available.
3558
3559- CONFIG_FLASH_SHOW_PROGRESS
3560		If defined (must be an integer), print out countdown
3561		digits and dots.  Recommended value: 45 (9..1) for 80
3562		column displays, 15 (3..1) for 40 column displays.
3563
3564- CONFIG_FLASH_VERIFY
3565		If defined, the content of the flash (destination) is compared
3566		against the source after the write operation. An error message
3567		will be printed when the contents are not identical.
3568		Please note that this option is useless in nearly all cases,
3569		since such flash programming errors usually are detected earlier
3570		while unprotecting/erasing/programming. Please only enable
3571		this option if you really know what you are doing.
3572
3573- CONFIG_SYS_RX_ETH_BUFFER:
3574		Defines the number of Ethernet receive buffers. On some
3575		Ethernet controllers it is recommended to set this value
3576		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3577		buffers can be full shortly after enabling the interface
3578		on high Ethernet traffic.
3579		Defaults to 4 if not defined.
3580
3581- CONFIG_ENV_MAX_ENTRIES
3582
3583	Maximum number of entries in the hash table that is used
3584	internally to store the environment settings. The default
3585	setting is supposed to be generous and should work in most
3586	cases. This setting can be used to tune behaviour; see
3587	lib/hashtable.c for details.
3588
3589- CONFIG_ENV_FLAGS_LIST_DEFAULT
3590- CONFIG_ENV_FLAGS_LIST_STATIC
3591	Enable validation of the values given to environment variables when
3592	calling env set.  Variables can be restricted to only decimal,
3593	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3594	the variables can also be restricted to IP address or MAC address.
3595
3596	The format of the list is:
3597		type_attribute = [s|d|x|b|i|m]
3598		access_atribute = [a|r|o|c]
3599		attributes = type_attribute[access_atribute]
3600		entry = variable_name[:attributes]
3601		list = entry[,list]
3602
3603	The type attributes are:
3604		s - String (default)
3605		d - Decimal
3606		x - Hexadecimal
3607		b - Boolean ([1yYtT|0nNfF])
3608		i - IP address
3609		m - MAC address
3610
3611	The access attributes are:
3612		a - Any (default)
3613		r - Read-only
3614		o - Write-once
3615		c - Change-default
3616
3617	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3618		Define this to a list (string) to define the ".flags"
3619		envirnoment variable in the default or embedded environment.
3620
3621	- CONFIG_ENV_FLAGS_LIST_STATIC
3622		Define this to a list (string) to define validation that
3623		should be done if an entry is not found in the ".flags"
3624		environment variable.  To override a setting in the static
3625		list, simply add an entry for the same variable name to the
3626		".flags" variable.
3627
3628- CONFIG_ENV_ACCESS_IGNORE_FORCE
3629	If defined, don't allow the -f switch to env set override variable
3630	access flags.
3631
3632- CONFIG_SYS_GENERIC_BOARD
3633	This selects the architecture-generic board system instead of the
3634	architecture-specific board files. It is intended to move boards
3635	to this new framework over time. Defining this will disable the
3636	arch/foo/lib/board.c file and use common/board_f.c and
3637	common/board_r.c instead. To use this option your architecture
3638	must support it (i.e. must define __HAVE_ARCH_GENERIC_BOARD in
3639	its config.mk file). If you find problems enabling this option on
3640	your board please report the problem and send patches!
3641
3642- CONFIG_SYS_SYM_OFFSETS
3643	This is set by architectures that use offsets for link symbols
3644	instead of absolute values. So bss_start is obtained using an
3645	offset _bss_start_ofs from CONFIG_SYS_TEXT_BASE, rather than
3646	directly. You should not need to touch this setting.
3647
3648- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
3649	This is set by OMAP boards for the max time that reset should
3650	be asserted. See doc/README.omap-reset-time for details on how
3651	the value can be calulated on a given board.
3652
3653The following definitions that deal with the placement and management
3654of environment data (variable area); in general, we support the
3655following configurations:
3656
3657- CONFIG_BUILD_ENVCRC:
3658
3659	Builds up envcrc with the target environment so that external utils
3660	may easily extract it and embed it in final U-Boot images.
3661
3662- CONFIG_ENV_IS_IN_FLASH:
3663
3664	Define this if the environment is in flash memory.
3665
3666	a) The environment occupies one whole flash sector, which is
3667	   "embedded" in the text segment with the U-Boot code. This
3668	   happens usually with "bottom boot sector" or "top boot
3669	   sector" type flash chips, which have several smaller
3670	   sectors at the start or the end. For instance, such a
3671	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3672	   such a case you would place the environment in one of the
3673	   4 kB sectors - with U-Boot code before and after it. With
3674	   "top boot sector" type flash chips, you would put the
3675	   environment in one of the last sectors, leaving a gap
3676	   between U-Boot and the environment.
3677
3678	- CONFIG_ENV_OFFSET:
3679
3680	   Offset of environment data (variable area) to the
3681	   beginning of flash memory; for instance, with bottom boot
3682	   type flash chips the second sector can be used: the offset
3683	   for this sector is given here.
3684
3685	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3686
3687	- CONFIG_ENV_ADDR:
3688
3689	   This is just another way to specify the start address of
3690	   the flash sector containing the environment (instead of
3691	   CONFIG_ENV_OFFSET).
3692
3693	- CONFIG_ENV_SECT_SIZE:
3694
3695	   Size of the sector containing the environment.
3696
3697
3698	b) Sometimes flash chips have few, equal sized, BIG sectors.
3699	   In such a case you don't want to spend a whole sector for
3700	   the environment.
3701
3702	- CONFIG_ENV_SIZE:
3703
3704	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3705	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3706	   of this flash sector for the environment. This saves
3707	   memory for the RAM copy of the environment.
3708
3709	   It may also save flash memory if you decide to use this
3710	   when your environment is "embedded" within U-Boot code,
3711	   since then the remainder of the flash sector could be used
3712	   for U-Boot code. It should be pointed out that this is
3713	   STRONGLY DISCOURAGED from a robustness point of view:
3714	   updating the environment in flash makes it always
3715	   necessary to erase the WHOLE sector. If something goes
3716	   wrong before the contents has been restored from a copy in
3717	   RAM, your target system will be dead.
3718
3719	- CONFIG_ENV_ADDR_REDUND
3720	  CONFIG_ENV_SIZE_REDUND
3721
3722	   These settings describe a second storage area used to hold
3723	   a redundant copy of the environment data, so that there is
3724	   a valid backup copy in case there is a power failure during
3725	   a "saveenv" operation.
3726
3727BE CAREFUL! Any changes to the flash layout, and some changes to the
3728source code will make it necessary to adapt <board>/u-boot.lds*
3729accordingly!
3730
3731
3732- CONFIG_ENV_IS_IN_NVRAM:
3733
3734	Define this if you have some non-volatile memory device
3735	(NVRAM, battery buffered SRAM) which you want to use for the
3736	environment.
3737
3738	- CONFIG_ENV_ADDR:
3739	- CONFIG_ENV_SIZE:
3740
3741	  These two #defines are used to determine the memory area you
3742	  want to use for environment. It is assumed that this memory
3743	  can just be read and written to, without any special
3744	  provision.
3745
3746BE CAREFUL! The first access to the environment happens quite early
3747in U-Boot initalization (when we try to get the setting of for the
3748console baudrate). You *MUST* have mapped your NVRAM area then, or
3749U-Boot will hang.
3750
3751Please note that even with NVRAM we still use a copy of the
3752environment in RAM: we could work on NVRAM directly, but we want to
3753keep settings there always unmodified except somebody uses "saveenv"
3754to save the current settings.
3755
3756
3757- CONFIG_ENV_IS_IN_EEPROM:
3758
3759	Use this if you have an EEPROM or similar serial access
3760	device and a driver for it.
3761
3762	- CONFIG_ENV_OFFSET:
3763	- CONFIG_ENV_SIZE:
3764
3765	  These two #defines specify the offset and size of the
3766	  environment area within the total memory of your EEPROM.
3767
3768	- CONFIG_SYS_I2C_EEPROM_ADDR:
3769	  If defined, specified the chip address of the EEPROM device.
3770	  The default address is zero.
3771
3772	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3773	  If defined, the number of bits used to address bytes in a
3774	  single page in the EEPROM device.  A 64 byte page, for example
3775	  would require six bits.
3776
3777	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3778	  If defined, the number of milliseconds to delay between
3779	  page writes.	The default is zero milliseconds.
3780
3781	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3782	  The length in bytes of the EEPROM memory array address.  Note
3783	  that this is NOT the chip address length!
3784
3785	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3786	  EEPROM chips that implement "address overflow" are ones
3787	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3788	  address and the extra bits end up in the "chip address" bit
3789	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3790	  byte chips.
3791
3792	  Note that we consider the length of the address field to
3793	  still be one byte because the extra address bits are hidden
3794	  in the chip address.
3795
3796	- CONFIG_SYS_EEPROM_SIZE:
3797	  The size in bytes of the EEPROM device.
3798
3799	- CONFIG_ENV_EEPROM_IS_ON_I2C
3800	  define this, if you have I2C and SPI activated, and your
3801	  EEPROM, which holds the environment, is on the I2C bus.
3802
3803	- CONFIG_I2C_ENV_EEPROM_BUS
3804	  if you have an Environment on an EEPROM reached over
3805	  I2C muxes, you can define here, how to reach this
3806	  EEPROM. For example:
3807
3808	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
3809
3810	  EEPROM which holds the environment, is reached over
3811	  a pca9547 i2c mux with address 0x70, channel 3.
3812
3813- CONFIG_ENV_IS_IN_DATAFLASH:
3814
3815	Define this if you have a DataFlash memory device which you
3816	want to use for the environment.
3817
3818	- CONFIG_ENV_OFFSET:
3819	- CONFIG_ENV_ADDR:
3820	- CONFIG_ENV_SIZE:
3821
3822	  These three #defines specify the offset and size of the
3823	  environment area within the total memory of your DataFlash placed
3824	  at the specified address.
3825
3826- CONFIG_ENV_IS_IN_REMOTE:
3827
3828	Define this if you have a remote memory space which you
3829	want to use for the local device's environment.
3830
3831	- CONFIG_ENV_ADDR:
3832	- CONFIG_ENV_SIZE:
3833
3834	  These two #defines specify the address and size of the
3835	  environment area within the remote memory space. The
3836	  local device can get the environment from remote memory
3837	  space by SRIO or PCIE links.
3838
3839BE CAREFUL! For some special cases, the local device can not use
3840"saveenv" command. For example, the local device will get the
3841environment stored in a remote NOR flash by SRIO or PCIE link,
3842but it can not erase, write this NOR flash by SRIO or PCIE interface.
3843
3844- CONFIG_ENV_IS_IN_NAND:
3845
3846	Define this if you have a NAND device which you want to use
3847	for the environment.
3848
3849	- CONFIG_ENV_OFFSET:
3850	- CONFIG_ENV_SIZE:
3851
3852	  These two #defines specify the offset and size of the environment
3853	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
3854	  aligned to an erase block boundary.
3855
3856	- CONFIG_ENV_OFFSET_REDUND (optional):
3857
3858	  This setting describes a second storage area of CONFIG_ENV_SIZE
3859	  size used to hold a redundant copy of the environment data, so
3860	  that there is a valid backup copy in case there is a power failure
3861	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
3862	  aligned to an erase block boundary.
3863
3864	- CONFIG_ENV_RANGE (optional):
3865
3866	  Specifies the length of the region in which the environment
3867	  can be written.  This should be a multiple of the NAND device's
3868	  block size.  Specifying a range with more erase blocks than
3869	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
3870	  the range to be avoided.
3871
3872	- CONFIG_ENV_OFFSET_OOB (optional):
3873
3874	  Enables support for dynamically retrieving the offset of the
3875	  environment from block zero's out-of-band data.  The
3876	  "nand env.oob" command can be used to record this offset.
3877	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
3878	  using CONFIG_ENV_OFFSET_OOB.
3879
3880- CONFIG_NAND_ENV_DST
3881
3882	Defines address in RAM to which the nand_spl code should copy the
3883	environment. If redundant environment is used, it will be copied to
3884	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3885
3886- CONFIG_ENV_IS_IN_UBI:
3887
3888	Define this if you have an UBI volume that you want to use for the
3889	environment.  This has the benefit of wear-leveling the environment
3890	accesses, which is important on NAND.
3891
3892	- CONFIG_ENV_UBI_PART:
3893
3894	  Define this to a string that is the mtd partition containing the UBI.
3895
3896	- CONFIG_ENV_UBI_VOLUME:
3897
3898	  Define this to the name of the volume that you want to store the
3899	  environment in.
3900
3901	- CONFIG_ENV_UBI_VOLUME_REDUND:
3902
3903	  Define this to the name of another volume to store a second copy of
3904	  the environment in.  This will enable redundant environments in UBI.
3905	  It is assumed that both volumes are in the same MTD partition.
3906
3907	- CONFIG_UBI_SILENCE_MSG
3908	- CONFIG_UBIFS_SILENCE_MSG
3909
3910	  You will probably want to define these to avoid a really noisy system
3911	  when storing the env in UBI.
3912
3913- CONFIG_ENV_IS_IN_MMC:
3914
3915	Define this if you have an MMC device which you want to use for the
3916	environment.
3917
3918	- CONFIG_SYS_MMC_ENV_DEV:
3919
3920	  Specifies which MMC device the environment is stored in.
3921
3922	- CONFIG_SYS_MMC_ENV_PART (optional):
3923
3924	  Specifies which MMC partition the environment is stored in. If not
3925	  set, defaults to partition 0, the user area. Common values might be
3926	  1 (first MMC boot partition), 2 (second MMC boot partition).
3927
3928	- CONFIG_ENV_OFFSET:
3929	- CONFIG_ENV_SIZE:
3930
3931	  These two #defines specify the offset and size of the environment
3932	  area within the specified MMC device.
3933
3934	  If offset is positive (the usual case), it is treated as relative to
3935	  the start of the MMC partition. If offset is negative, it is treated
3936	  as relative to the end of the MMC partition. This can be useful if
3937	  your board may be fitted with different MMC devices, which have
3938	  different sizes for the MMC partitions, and you always want the
3939	  environment placed at the very end of the partition, to leave the
3940	  maximum possible space before it, to store other data.
3941
3942	  These two values are in units of bytes, but must be aligned to an
3943	  MMC sector boundary.
3944
3945	- CONFIG_ENV_OFFSET_REDUND (optional):
3946
3947	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
3948	  hold a redundant copy of the environment data. This provides a
3949	  valid backup copy in case the other copy is corrupted, e.g. due
3950	  to a power failure during a "saveenv" operation.
3951
3952	  This value may also be positive or negative; this is handled in the
3953	  same way as CONFIG_ENV_OFFSET.
3954
3955	  This value is also in units of bytes, but must also be aligned to
3956	  an MMC sector boundary.
3957
3958	- CONFIG_ENV_SIZE_REDUND (optional):
3959
3960	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
3961	  set. If this value is set, it must be set to the same value as
3962	  CONFIG_ENV_SIZE.
3963
3964- CONFIG_SYS_SPI_INIT_OFFSET
3965
3966	Defines offset to the initial SPI buffer area in DPRAM. The
3967	area is used at an early stage (ROM part) if the environment
3968	is configured to reside in the SPI EEPROM: We need a 520 byte
3969	scratch DPRAM area. It is used between the two initialization
3970	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
3971	to be a good choice since it makes it far enough from the
3972	start of the data area as well as from the stack pointer.
3973
3974Please note that the environment is read-only until the monitor
3975has been relocated to RAM and a RAM copy of the environment has been
3976created; also, when using EEPROM you will have to use getenv_f()
3977until then to read environment variables.
3978
3979The environment is protected by a CRC32 checksum. Before the monitor
3980is relocated into RAM, as a result of a bad CRC you will be working
3981with the compiled-in default environment - *silently*!!! [This is
3982necessary, because the first environment variable we need is the
3983"baudrate" setting for the console - if we have a bad CRC, we don't
3984have any device yet where we could complain.]
3985
3986Note: once the monitor has been relocated, then it will complain if
3987the default environment is used; a new CRC is computed as soon as you
3988use the "saveenv" command to store a valid environment.
3989
3990- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
3991		Echo the inverted Ethernet link state to the fault LED.
3992
3993		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
3994		      also needs to be defined.
3995
3996- CONFIG_SYS_FAULT_MII_ADDR:
3997		MII address of the PHY to check for the Ethernet link state.
3998
3999- CONFIG_NS16550_MIN_FUNCTIONS:
4000		Define this if you desire to only have use of the NS16550_init
4001		and NS16550_putc functions for the serial driver located at
4002		drivers/serial/ns16550.c.  This option is useful for saving
4003		space for already greatly restricted images, including but not
4004		limited to NAND_SPL configurations.
4005
4006- CONFIG_DISPLAY_BOARDINFO
4007		Display information about the board that U-Boot is running on
4008		when U-Boot starts up. The board function checkboard() is called
4009		to do this.
4010
4011- CONFIG_DISPLAY_BOARDINFO_LATE
4012		Similar to the previous option, but display this information
4013		later, once stdio is running and output goes to the LCD, if
4014		present.
4015
4016Low Level (hardware related) configuration options:
4017---------------------------------------------------
4018
4019- CONFIG_SYS_CACHELINE_SIZE:
4020		Cache Line Size of the CPU.
4021
4022- CONFIG_SYS_DEFAULT_IMMR:
4023		Default address of the IMMR after system reset.
4024
4025		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4026		and RPXsuper) to be able to adjust the position of
4027		the IMMR register after a reset.
4028
4029- CONFIG_SYS_CCSRBAR_DEFAULT:
4030		Default (power-on reset) physical address of CCSR on Freescale
4031		PowerPC SOCs.
4032
4033- CONFIG_SYS_CCSRBAR:
4034		Virtual address of CCSR.  On a 32-bit build, this is typically
4035		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4036
4037		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4038		for cross-platform code that uses that macro instead.
4039
4040- CONFIG_SYS_CCSRBAR_PHYS:
4041		Physical address of CCSR.  CCSR can be relocated to a new
4042		physical address, if desired.  In this case, this macro should
4043		be set to that address.	 Otherwise, it should be set to the
4044		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
4045		is typically relocated on 36-bit builds.  It is recommended
4046		that this macro be defined via the _HIGH and _LOW macros:
4047
4048		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4049			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4050
4051- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4052		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
4053		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
4054		used in assembly code, so it must not contain typecasts or
4055		integer size suffixes (e.g. "ULL").
4056
4057- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4058		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
4059		used in assembly code, so it must not contain typecasts or
4060		integer size suffixes (e.g. "ULL").
4061
4062- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
4063		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4064		forced to a value that ensures that CCSR is not relocated.
4065
4066- Floppy Disk Support:
4067		CONFIG_SYS_FDC_DRIVE_NUMBER
4068
4069		the default drive number (default value 0)
4070
4071		CONFIG_SYS_ISA_IO_STRIDE
4072
4073		defines the spacing between FDC chipset registers
4074		(default value 1)
4075
4076		CONFIG_SYS_ISA_IO_OFFSET
4077
4078		defines the offset of register from address. It
4079		depends on which part of the data bus is connected to
4080		the FDC chipset. (default value 0)
4081
4082		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4083		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4084		default value.
4085
4086		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4087		fdc_hw_init() is called at the beginning of the FDC
4088		setup. fdc_hw_init() must be provided by the board
4089		source code. It is used to make hardware dependant
4090		initializations.
4091
4092- CONFIG_IDE_AHB:
4093		Most IDE controllers were designed to be connected with PCI
4094		interface. Only few of them were designed for AHB interface.
4095		When software is doing ATA command and data transfer to
4096		IDE devices through IDE-AHB controller, some additional
4097		registers accessing to these kind of IDE-AHB controller
4098		is requierd.
4099
4100- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4101		DO NOT CHANGE unless you know exactly what you're
4102		doing! (11-4) [MPC8xx/82xx systems only]
4103
4104- CONFIG_SYS_INIT_RAM_ADDR:
4105
4106		Start address of memory area that can be used for
4107		initial data and stack; please note that this must be
4108		writable memory that is working WITHOUT special
4109		initialization, i. e. you CANNOT use normal RAM which
4110		will become available only after programming the
4111		memory controller and running certain initialization
4112		sequences.
4113
4114		U-Boot uses the following memory types:
4115		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4116		- MPC824X: data cache
4117		- PPC4xx:  data cache
4118
4119- CONFIG_SYS_GBL_DATA_OFFSET:
4120
4121		Offset of the initial data structure in the memory
4122		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4123		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4124		data is located at the end of the available space
4125		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4126		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
4127		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4128		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4129
4130	Note:
4131		On the MPC824X (or other systems that use the data
4132		cache for initial memory) the address chosen for
4133		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4134		point to an otherwise UNUSED address space between
4135		the top of RAM and the start of the PCI space.
4136
4137- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4138
4139- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4140
4141- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4142
4143- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4144
4145- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4146
4147- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4148
4149- CONFIG_SYS_OR_TIMING_SDRAM:
4150		SDRAM timing
4151
4152- CONFIG_SYS_MAMR_PTA:
4153		periodic timer for refresh
4154
4155- CONFIG_SYS_DER:	Debug Event Register (37-47)
4156
4157- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4158  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4159  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4160  CONFIG_SYS_BR1_PRELIM:
4161		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4162
4163- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4164  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4165  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4166		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4167
4168- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4169  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4170		Machine Mode Register and Memory Periodic Timer
4171		Prescaler definitions (SDRAM timing)
4172
4173- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4174		enable I2C microcode relocation patch (MPC8xx);
4175		define relocation offset in DPRAM [DSP2]
4176
4177- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4178		enable SMC microcode relocation patch (MPC8xx);
4179		define relocation offset in DPRAM [SMC1]
4180
4181- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4182		enable SPI microcode relocation patch (MPC8xx);
4183		define relocation offset in DPRAM [SCC4]
4184
4185- CONFIG_SYS_USE_OSCCLK:
4186		Use OSCM clock mode on MBX8xx board. Be careful,
4187		wrong setting might damage your board. Read
4188		doc/README.MBX before setting this variable!
4189
4190- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4191		Offset of the bootmode word in DPRAM used by post
4192		(Power On Self Tests). This definition overrides
4193		#define'd default value in commproc.h resp.
4194		cpm_8260.h.
4195
4196- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4197  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4198  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4199  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4200  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4201  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4202  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4203  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4204		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4205
4206- CONFIG_PCI_DISABLE_PCIE:
4207		Disable PCI-Express on systems where it is supported but not
4208		required.
4209
4210- CONFIG_PCI_ENUM_ONLY
4211		Only scan through and get the devices on the busses.
4212		Don't do any setup work, presumably because someone or
4213		something has already done it, and we don't need to do it
4214		a second time.	Useful for platforms that are pre-booted
4215		by coreboot or similar.
4216
4217- CONFIG_PCI_INDIRECT_BRIDGE:
4218		Enable support for indirect PCI bridges.
4219
4220- CONFIG_SYS_SRIO:
4221		Chip has SRIO or not
4222
4223- CONFIG_SRIO1:
4224		Board has SRIO 1 port available
4225
4226- CONFIG_SRIO2:
4227		Board has SRIO 2 port available
4228
4229- CONFIG_SRIO_PCIE_BOOT_MASTER
4230		Board can support master function for Boot from SRIO and PCIE
4231
4232- CONFIG_SYS_SRIOn_MEM_VIRT:
4233		Virtual Address of SRIO port 'n' memory region
4234
4235- CONFIG_SYS_SRIOn_MEM_PHYS:
4236		Physical Address of SRIO port 'n' memory region
4237
4238- CONFIG_SYS_SRIOn_MEM_SIZE:
4239		Size of SRIO port 'n' memory region
4240
4241- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4242		Defined to tell the NAND controller that the NAND chip is using
4243		a 16 bit bus.
4244		Not all NAND drivers use this symbol.
4245		Example of drivers that use it:
4246		- drivers/mtd/nand/ndfc.c
4247		- drivers/mtd/nand/mxc_nand.c
4248
4249- CONFIG_SYS_NDFC_EBC0_CFG
4250		Sets the EBC0_CFG register for the NDFC. If not defined
4251		a default value will be used.
4252
4253- CONFIG_SPD_EEPROM
4254		Get DDR timing information from an I2C EEPROM. Common
4255		with pluggable memory modules such as SODIMMs
4256
4257  SPD_EEPROM_ADDRESS
4258		I2C address of the SPD EEPROM
4259
4260- CONFIG_SYS_SPD_BUS_NUM
4261		If SPD EEPROM is on an I2C bus other than the first
4262		one, specify here. Note that the value must resolve
4263		to something your driver can deal with.
4264
4265- CONFIG_SYS_DDR_RAW_TIMING
4266		Get DDR timing information from other than SPD. Common with
4267		soldered DDR chips onboard without SPD. DDR raw timing
4268		parameters are extracted from datasheet and hard-coded into
4269		header files or board specific files.
4270
4271- CONFIG_FSL_DDR_INTERACTIVE
4272		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4273
4274- CONFIG_SYS_83XX_DDR_USES_CS0
4275		Only for 83xx systems. If specified, then DDR should
4276		be configured using CS0 and CS1 instead of CS2 and CS3.
4277
4278- CONFIG_ETHER_ON_FEC[12]
4279		Define to enable FEC[12] on a 8xx series processor.
4280
4281- CONFIG_FEC[12]_PHY
4282		Define to the hardcoded PHY address which corresponds
4283		to the given FEC; i. e.
4284			#define CONFIG_FEC1_PHY 4
4285		means that the PHY with address 4 is connected to FEC1
4286
4287		When set to -1, means to probe for first available.
4288
4289- CONFIG_FEC[12]_PHY_NORXERR
4290		The PHY does not have a RXERR line (RMII only).
4291		(so program the FEC to ignore it).
4292
4293- CONFIG_RMII
4294		Enable RMII mode for all FECs.
4295		Note that this is a global option, we can't
4296		have one FEC in standard MII mode and another in RMII mode.
4297
4298- CONFIG_CRC32_VERIFY
4299		Add a verify option to the crc32 command.
4300		The syntax is:
4301
4302		=> crc32 -v <address> <count> <crc32>
4303
4304		Where address/count indicate a memory area
4305		and crc32 is the correct crc32 which the
4306		area should have.
4307
4308- CONFIG_LOOPW
4309		Add the "loopw" memory command. This only takes effect if
4310		the memory commands are activated globally (CONFIG_CMD_MEM).
4311
4312- CONFIG_MX_CYCLIC
4313		Add the "mdc" and "mwc" memory commands. These are cyclic
4314		"md/mw" commands.
4315		Examples:
4316
4317		=> mdc.b 10 4 500
4318		This command will print 4 bytes (10,11,12,13) each 500 ms.
4319
4320		=> mwc.l 100 12345678 10
4321		This command will write 12345678 to address 100 all 10 ms.
4322
4323		This only takes effect if the memory commands are activated
4324		globally (CONFIG_CMD_MEM).
4325
4326- CONFIG_SKIP_LOWLEVEL_INIT
4327		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4328		low level initializations (like setting up the memory
4329		controller) are omitted and/or U-Boot does not
4330		relocate itself into RAM.
4331
4332		Normally this variable MUST NOT be defined. The only
4333		exception is when U-Boot is loaded (to RAM) by some
4334		other boot loader or by a debugger which performs
4335		these initializations itself.
4336
4337- CONFIG_SPL_BUILD
4338		Modifies the behaviour of start.S when compiling a loader
4339		that is executed before the actual U-Boot. E.g. when
4340		compiling a NAND SPL.
4341
4342- CONFIG_TPL_BUILD
4343		Modifies the behaviour of start.S  when compiling a loader
4344		that is executed after the SPL and before the actual U-Boot.
4345		It is loaded by the SPL.
4346
4347- CONFIG_SYS_MPC85XX_NO_RESETVEC
4348		Only for 85xx systems. If this variable is specified, the section
4349		.resetvec is not kept and the section .bootpg is placed in the
4350		previous 4k of the .text section.
4351
4352- CONFIG_ARCH_MAP_SYSMEM
4353		Generally U-Boot (and in particular the md command) uses
4354		effective address. It is therefore not necessary to regard
4355		U-Boot address as virtual addresses that need to be translated
4356		to physical addresses. However, sandbox requires this, since
4357		it maintains its own little RAM buffer which contains all
4358		addressable memory. This option causes some memory accesses
4359		to be mapped through map_sysmem() / unmap_sysmem().
4360
4361- CONFIG_USE_ARCH_MEMCPY
4362  CONFIG_USE_ARCH_MEMSET
4363		If these options are used a optimized version of memcpy/memset will
4364		be used if available. These functions may be faster under some
4365		conditions but may increase the binary size.
4366
4367- CONFIG_X86_RESET_VECTOR
4368		If defined, the x86 reset vector code is included. This is not
4369		needed when U-Boot is running from Coreboot.
4370
4371- CONFIG_SYS_MPUCLK
4372		Defines the MPU clock speed (in MHz).
4373
4374		NOTE : currently only supported on AM335x platforms.
4375
4376Freescale QE/FMAN Firmware Support:
4377-----------------------------------
4378
4379The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4380loading of "firmware", which is encoded in the QE firmware binary format.
4381This firmware often needs to be loaded during U-Boot booting, so macros
4382are used to identify the storage device (NOR flash, SPI, etc) and the address
4383within that device.
4384
4385- CONFIG_SYS_QE_FMAN_FW_ADDR
4386	The address in the storage device where the firmware is located.  The
4387	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4388	is also specified.
4389
4390- CONFIG_SYS_QE_FMAN_FW_LENGTH
4391	The maximum possible size of the firmware.  The firmware binary format
4392	has a field that specifies the actual size of the firmware, but it
4393	might not be possible to read any part of the firmware unless some
4394	local storage is allocated to hold the entire firmware first.
4395
4396- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4397	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4398	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4399	virtual address in NOR flash.
4400
4401- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4402	Specifies that QE/FMAN firmware is located in NAND flash.
4403	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4404
4405- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4406	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4407	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4408
4409- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
4410	Specifies that QE/FMAN firmware is located on the primary SPI
4411	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4412
4413- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4414	Specifies that QE/FMAN firmware is located in the remote (master)
4415	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4416	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4417	window->master inbound window->master LAW->the ucode address in
4418	master's memory space.
4419
4420Building the Software:
4421======================
4422
4423Building U-Boot has been tested in several native build environments
4424and in many different cross environments. Of course we cannot support
4425all possibly existing versions of cross development tools in all
4426(potentially obsolete) versions. In case of tool chain problems we
4427recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4428which is extensively used to build and test U-Boot.
4429
4430If you are not using a native environment, it is assumed that you
4431have GNU cross compiling tools available in your path. In this case,
4432you must set the environment variable CROSS_COMPILE in your shell.
4433Note that no changes to the Makefile or any other source files are
4434necessary. For example using the ELDK on a 4xx CPU, please enter:
4435
4436	$ CROSS_COMPILE=ppc_4xx-
4437	$ export CROSS_COMPILE
4438
4439Note: If you wish to generate Windows versions of the utilities in
4440      the tools directory you can use the MinGW toolchain
4441      (http://www.mingw.org).  Set your HOST tools to the MinGW
4442      toolchain and execute 'make tools'.  For example:
4443
4444       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4445
4446      Binaries such as tools/mkimage.exe will be created which can
4447      be executed on computers running Windows.
4448
4449U-Boot is intended to be simple to build. After installing the
4450sources you must configure U-Boot for one specific board type. This
4451is done by typing:
4452
4453	make NAME_config
4454
4455where "NAME_config" is the name of one of the existing configu-
4456rations; see boards.cfg for supported names.
4457
4458Note: for some board special configuration names may exist; check if
4459      additional information is available from the board vendor; for
4460      instance, the TQM823L systems are available without (standard)
4461      or with LCD support. You can select such additional "features"
4462      when choosing the configuration, i. e.
4463
4464      make TQM823L_config
4465	- will configure for a plain TQM823L, i. e. no LCD support
4466
4467      make TQM823L_LCD_config
4468	- will configure for a TQM823L with U-Boot console on LCD
4469
4470      etc.
4471
4472
4473Finally, type "make all", and you should get some working U-Boot
4474images ready for download to / installation on your system:
4475
4476- "u-boot.bin" is a raw binary image
4477- "u-boot" is an image in ELF binary format
4478- "u-boot.srec" is in Motorola S-Record format
4479
4480By default the build is performed locally and the objects are saved
4481in the source directory. One of the two methods can be used to change
4482this behavior and build U-Boot to some external directory:
4483
44841. Add O= to the make command line invocations:
4485
4486	make O=/tmp/build distclean
4487	make O=/tmp/build NAME_config
4488	make O=/tmp/build all
4489
44902. Set environment variable BUILD_DIR to point to the desired location:
4491
4492	export BUILD_DIR=/tmp/build
4493	make distclean
4494	make NAME_config
4495	make all
4496
4497Note that the command line "O=" setting overrides the BUILD_DIR environment
4498variable.
4499
4500
4501Please be aware that the Makefiles assume you are using GNU make, so
4502for instance on NetBSD you might need to use "gmake" instead of
4503native "make".
4504
4505
4506If the system board that you have is not listed, then you will need
4507to port U-Boot to your hardware platform. To do this, follow these
4508steps:
4509
45101.  Add a new configuration option for your board to the toplevel
4511    "boards.cfg" file, using the existing entries as examples.
4512    Follow the instructions there to keep the boards in order.
45132.  Create a new directory to hold your board specific code. Add any
4514    files you need. In your board directory, you will need at least
4515    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
45163.  Create a new configuration file "include/configs/<board>.h" for
4517    your board
45183.  If you're porting U-Boot to a new CPU, then also create a new
4519    directory to hold your CPU specific code. Add any files you need.
45204.  Run "make <board>_config" with your new name.
45215.  Type "make", and you should get a working "u-boot.srec" file
4522    to be installed on your target system.
45236.  Debug and solve any problems that might arise.
4524    [Of course, this last step is much harder than it sounds.]
4525
4526
4527Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4528==============================================================
4529
4530If you have modified U-Boot sources (for instance added a new board
4531or support for new devices, a new CPU, etc.) you are expected to
4532provide feedback to the other developers. The feedback normally takes
4533the form of a "patch", i. e. a context diff against a certain (latest
4534official or latest in the git repository) version of U-Boot sources.
4535
4536But before you submit such a patch, please verify that your modifi-
4537cation did not break existing code. At least make sure that *ALL* of
4538the supported boards compile WITHOUT ANY compiler warnings. To do so,
4539just run the "MAKEALL" script, which will configure and build U-Boot
4540for ALL supported system. Be warned, this will take a while. You can
4541select which (cross) compiler to use by passing a `CROSS_COMPILE'
4542environment variable to the script, i. e. to use the ELDK cross tools
4543you can type
4544
4545	CROSS_COMPILE=ppc_8xx- MAKEALL
4546
4547or to build on a native PowerPC system you can type
4548
4549	CROSS_COMPILE=' ' MAKEALL
4550
4551When using the MAKEALL script, the default behaviour is to build
4552U-Boot in the source directory. This location can be changed by
4553setting the BUILD_DIR environment variable. Also, for each target
4554built, the MAKEALL script saves two log files (<target>.ERR and
4555<target>.MAKEALL) in the <source dir>/LOG directory. This default
4556location can be changed by setting the MAKEALL_LOGDIR environment
4557variable. For example:
4558
4559	export BUILD_DIR=/tmp/build
4560	export MAKEALL_LOGDIR=/tmp/log
4561	CROSS_COMPILE=ppc_8xx- MAKEALL
4562
4563With the above settings build objects are saved in the /tmp/build,
4564log files are saved in the /tmp/log and the source tree remains clean
4565during the whole build process.
4566
4567
4568See also "U-Boot Porting Guide" below.
4569
4570
4571Monitor Commands - Overview:
4572============================
4573
4574go	- start application at address 'addr'
4575run	- run commands in an environment variable
4576bootm	- boot application image from memory
4577bootp	- boot image via network using BootP/TFTP protocol
4578bootz   - boot zImage from memory
4579tftpboot- boot image via network using TFTP protocol
4580	       and env variables "ipaddr" and "serverip"
4581	       (and eventually "gatewayip")
4582tftpput - upload a file via network using TFTP protocol
4583rarpboot- boot image via network using RARP/TFTP protocol
4584diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4585loads	- load S-Record file over serial line
4586loadb	- load binary file over serial line (kermit mode)
4587md	- memory display
4588mm	- memory modify (auto-incrementing)
4589nm	- memory modify (constant address)
4590mw	- memory write (fill)
4591cp	- memory copy
4592cmp	- memory compare
4593crc32	- checksum calculation
4594i2c	- I2C sub-system
4595sspi	- SPI utility commands
4596base	- print or set address offset
4597printenv- print environment variables
4598setenv	- set environment variables
4599saveenv - save environment variables to persistent storage
4600protect - enable or disable FLASH write protection
4601erase	- erase FLASH memory
4602flinfo	- print FLASH memory information
4603nand	- NAND memory operations (see doc/README.nand)
4604bdinfo	- print Board Info structure
4605iminfo	- print header information for application image
4606coninfo - print console devices and informations
4607ide	- IDE sub-system
4608loop	- infinite loop on address range
4609loopw	- infinite write loop on address range
4610mtest	- simple RAM test
4611icache	- enable or disable instruction cache
4612dcache	- enable or disable data cache
4613reset	- Perform RESET of the CPU
4614echo	- echo args to console
4615version - print monitor version
4616help	- print online help
4617?	- alias for 'help'
4618
4619
4620Monitor Commands - Detailed Description:
4621========================================
4622
4623TODO.
4624
4625For now: just type "help <command>".
4626
4627
4628Environment Variables:
4629======================
4630
4631U-Boot supports user configuration using Environment Variables which
4632can be made persistent by saving to Flash memory.
4633
4634Environment Variables are set using "setenv", printed using
4635"printenv", and saved to Flash using "saveenv". Using "setenv"
4636without a value can be used to delete a variable from the
4637environment. As long as you don't save the environment you are
4638working with an in-memory copy. In case the Flash area containing the
4639environment is erased by accident, a default environment is provided.
4640
4641Some configuration options can be set using Environment Variables.
4642
4643List of environment variables (most likely not complete):
4644
4645  baudrate	- see CONFIG_BAUDRATE
4646
4647  bootdelay	- see CONFIG_BOOTDELAY
4648
4649  bootcmd	- see CONFIG_BOOTCOMMAND
4650
4651  bootargs	- Boot arguments when booting an RTOS image
4652
4653  bootfile	- Name of the image to load with TFTP
4654
4655  bootm_low	- Memory range available for image processing in the bootm
4656		  command can be restricted. This variable is given as
4657		  a hexadecimal number and defines lowest address allowed
4658		  for use by the bootm command. See also "bootm_size"
4659		  environment variable. Address defined by "bootm_low" is
4660		  also the base of the initial memory mapping for the Linux
4661		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
4662		  bootm_mapsize.
4663
4664  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
4665		  This variable is given as a hexadecimal number and it
4666		  defines the size of the memory region starting at base
4667		  address bootm_low that is accessible by the Linux kernel
4668		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
4669		  as the default value if it is defined, and bootm_size is
4670		  used otherwise.
4671
4672  bootm_size	- Memory range available for image processing in the bootm
4673		  command can be restricted. This variable is given as
4674		  a hexadecimal number and defines the size of the region
4675		  allowed for use by the bootm command. See also "bootm_low"
4676		  environment variable.
4677
4678  updatefile	- Location of the software update file on a TFTP server, used
4679		  by the automatic software update feature. Please refer to
4680		  documentation in doc/README.update for more details.
4681
4682  autoload	- if set to "no" (any string beginning with 'n'),
4683		  "bootp" will just load perform a lookup of the
4684		  configuration from the BOOTP server, but not try to
4685		  load any image using TFTP
4686
4687  autostart	- if set to "yes", an image loaded using the "bootp",
4688		  "rarpboot", "tftpboot" or "diskboot" commands will
4689		  be automatically started (by internally calling
4690		  "bootm")
4691
4692		  If set to "no", a standalone image passed to the
4693		  "bootm" command will be copied to the load address
4694		  (and eventually uncompressed), but NOT be started.
4695		  This can be used to load and uncompress arbitrary
4696		  data.
4697
4698  fdt_high	- if set this restricts the maximum address that the
4699		  flattened device tree will be copied into upon boot.
4700		  For example, if you have a system with 1 GB memory
4701		  at physical address 0x10000000, while Linux kernel
4702		  only recognizes the first 704 MB as low memory, you
4703		  may need to set fdt_high as 0x3C000000 to have the
4704		  device tree blob be copied to the maximum address
4705		  of the 704 MB low memory, so that Linux kernel can
4706		  access it during the boot procedure.
4707
4708		  If this is set to the special value 0xFFFFFFFF then
4709		  the fdt will not be copied at all on boot.  For this
4710		  to work it must reside in writable memory, have
4711		  sufficient padding on the end of it for u-boot to
4712		  add the information it needs into it, and the memory
4713		  must be accessible by the kernel.
4714
4715  fdtcontroladdr- if set this is the address of the control flattened
4716		  device tree used by U-Boot when CONFIG_OF_CONTROL is
4717		  defined.
4718
4719  i2cfast	- (PPC405GP|PPC405EP only)
4720		  if set to 'y' configures Linux I2C driver for fast
4721		  mode (400kHZ). This environment variable is used in
4722		  initialization code. So, for changes to be effective
4723		  it must be saved and board must be reset.
4724
4725  initrd_high	- restrict positioning of initrd images:
4726		  If this variable is not set, initrd images will be
4727		  copied to the highest possible address in RAM; this
4728		  is usually what you want since it allows for
4729		  maximum initrd size. If for some reason you want to
4730		  make sure that the initrd image is loaded below the
4731		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
4732		  variable to a value of "no" or "off" or "0".
4733		  Alternatively, you can set it to a maximum upper
4734		  address to use (U-Boot will still check that it
4735		  does not overwrite the U-Boot stack and data).
4736
4737		  For instance, when you have a system with 16 MB
4738		  RAM, and want to reserve 4 MB from use by Linux,
4739		  you can do this by adding "mem=12M" to the value of
4740		  the "bootargs" variable. However, now you must make
4741		  sure that the initrd image is placed in the first
4742		  12 MB as well - this can be done with
4743
4744		  setenv initrd_high 00c00000
4745
4746		  If you set initrd_high to 0xFFFFFFFF, this is an
4747		  indication to U-Boot that all addresses are legal
4748		  for the Linux kernel, including addresses in flash
4749		  memory. In this case U-Boot will NOT COPY the
4750		  ramdisk at all. This may be useful to reduce the
4751		  boot time on your system, but requires that this
4752		  feature is supported by your Linux kernel.
4753
4754  ipaddr	- IP address; needed for tftpboot command
4755
4756  loadaddr	- Default load address for commands like "bootp",
4757		  "rarpboot", "tftpboot", "loadb" or "diskboot"
4758
4759  loads_echo	- see CONFIG_LOADS_ECHO
4760
4761  serverip	- TFTP server IP address; needed for tftpboot command
4762
4763  bootretry	- see CONFIG_BOOT_RETRY_TIME
4764
4765  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
4766
4767  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
4768
4769  ethprime	- controls which interface is used first.
4770
4771  ethact	- controls which interface is currently active.
4772		  For example you can do the following
4773
4774		  => setenv ethact FEC
4775		  => ping 192.168.0.1 # traffic sent on FEC
4776		  => setenv ethact SCC
4777		  => ping 10.0.0.1 # traffic sent on SCC
4778
4779  ethrotate	- When set to "no" U-Boot does not go through all
4780		  available network interfaces.
4781		  It just stays at the currently selected interface.
4782
4783  netretry	- When set to "no" each network operation will
4784		  either succeed or fail without retrying.
4785		  When set to "once" the network operation will
4786		  fail when all the available network interfaces
4787		  are tried once without success.
4788		  Useful on scripts which control the retry operation
4789		  themselves.
4790
4791  npe_ucode	- set load address for the NPE microcode
4792
4793  silent_linux  - If set then linux will be told to boot silently, by
4794		  changing the console to be empty. If "yes" it will be
4795		  made silent. If "no" it will not be made silent. If
4796		  unset, then it will be made silent if the U-Boot console
4797		  is silent.
4798
4799  tftpsrcport	- If this is set, the value is used for TFTP's
4800		  UDP source port.
4801
4802  tftpdstport	- If this is set, the value is used for TFTP's UDP
4803		  destination port instead of the Well Know Port 69.
4804
4805  tftpblocksize - Block size to use for TFTP transfers; if not set,
4806		  we use the TFTP server's default block size
4807
4808  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
4809		  seconds, minimum value is 1000 = 1 second). Defines
4810		  when a packet is considered to be lost so it has to
4811		  be retransmitted. The default is 5000 = 5 seconds.
4812		  Lowering this value may make downloads succeed
4813		  faster in networks with high packet loss rates or
4814		  with unreliable TFTP servers.
4815
4816  vlan		- When set to a value < 4095 the traffic over
4817		  Ethernet is encapsulated/received over 802.1q
4818		  VLAN tagged frames.
4819
4820The following image location variables contain the location of images
4821used in booting. The "Image" column gives the role of the image and is
4822not an environment variable name. The other columns are environment
4823variable names. "File Name" gives the name of the file on a TFTP
4824server, "RAM Address" gives the location in RAM the image will be
4825loaded to, and "Flash Location" gives the image's address in NOR
4826flash or offset in NAND flash.
4827
4828*Note* - these variables don't have to be defined for all boards, some
4829boards currenlty use other variables for these purposes, and some
4830boards use these variables for other purposes.
4831
4832Image		    File Name	     RAM Address       Flash Location
4833-----		    ---------	     -----------       --------------
4834u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
4835Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
4836device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
4837ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
4838
4839The following environment variables may be used and automatically
4840updated by the network boot commands ("bootp" and "rarpboot"),
4841depending the information provided by your boot server:
4842
4843  bootfile	- see above
4844  dnsip		- IP address of your Domain Name Server
4845  dnsip2	- IP address of your secondary Domain Name Server
4846  gatewayip	- IP address of the Gateway (Router) to use
4847  hostname	- Target hostname
4848  ipaddr	- see above
4849  netmask	- Subnet Mask
4850  rootpath	- Pathname of the root filesystem on the NFS server
4851  serverip	- see above
4852
4853
4854There are two special Environment Variables:
4855
4856  serial#	- contains hardware identification information such
4857		  as type string and/or serial number
4858  ethaddr	- Ethernet address
4859
4860These variables can be set only once (usually during manufacturing of
4861the board). U-Boot refuses to delete or overwrite these variables
4862once they have been set once.
4863
4864
4865Further special Environment Variables:
4866
4867  ver		- Contains the U-Boot version string as printed
4868		  with the "version" command. This variable is
4869		  readonly (see CONFIG_VERSION_VARIABLE).
4870
4871
4872Please note that changes to some configuration parameters may take
4873only effect after the next boot (yes, that's just like Windoze :-).
4874
4875
4876Callback functions for environment variables:
4877---------------------------------------------
4878
4879For some environment variables, the behavior of u-boot needs to change
4880when their values are changed.  This functionailty allows functions to
4881be associated with arbitrary variables.  On creation, overwrite, or
4882deletion, the callback will provide the opportunity for some side
4883effect to happen or for the change to be rejected.
4884
4885The callbacks are named and associated with a function using the
4886U_BOOT_ENV_CALLBACK macro in your board or driver code.
4887
4888These callbacks are associated with variables in one of two ways.  The
4889static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
4890in the board configuration to a string that defines a list of
4891associations.  The list must be in the following format:
4892
4893	entry = variable_name[:callback_name]
4894	list = entry[,list]
4895
4896If the callback name is not specified, then the callback is deleted.
4897Spaces are also allowed anywhere in the list.
4898
4899Callbacks can also be associated by defining the ".callbacks" variable
4900with the same list format above.  Any association in ".callbacks" will
4901override any association in the static list. You can define
4902CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
4903".callbacks" envirnoment variable in the default or embedded environment.
4904
4905
4906Command Line Parsing:
4907=====================
4908
4909There are two different command line parsers available with U-Boot:
4910the old "simple" one, and the much more powerful "hush" shell:
4911
4912Old, simple command line parser:
4913--------------------------------
4914
4915- supports environment variables (through setenv / saveenv commands)
4916- several commands on one line, separated by ';'
4917- variable substitution using "... ${name} ..." syntax
4918- special characters ('$', ';') can be escaped by prefixing with '\',
4919  for example:
4920	setenv bootcmd bootm \${address}
4921- You can also escape text by enclosing in single apostrophes, for example:
4922	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
4923
4924Hush shell:
4925-----------
4926
4927- similar to Bourne shell, with control structures like
4928  if...then...else...fi, for...do...done; while...do...done,
4929  until...do...done, ...
4930- supports environment ("global") variables (through setenv / saveenv
4931  commands) and local shell variables (through standard shell syntax
4932  "name=value"); only environment variables can be used with "run"
4933  command
4934
4935General rules:
4936--------------
4937
4938(1) If a command line (or an environment variable executed by a "run"
4939    command) contains several commands separated by semicolon, and
4940    one of these commands fails, then the remaining commands will be
4941    executed anyway.
4942
4943(2) If you execute several variables with one call to run (i. e.
4944    calling run with a list of variables as arguments), any failing
4945    command will cause "run" to terminate, i. e. the remaining
4946    variables are not executed.
4947
4948Note for Redundant Ethernet Interfaces:
4949=======================================
4950
4951Some boards come with redundant Ethernet interfaces; U-Boot supports
4952such configurations and is capable of automatic selection of a
4953"working" interface when needed. MAC assignment works as follows:
4954
4955Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
4956MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
4957"eth1addr" (=>eth1), "eth2addr", ...
4958
4959If the network interface stores some valid MAC address (for instance
4960in SROM), this is used as default address if there is NO correspon-
4961ding setting in the environment; if the corresponding environment
4962variable is set, this overrides the settings in the card; that means:
4963
4964o If the SROM has a valid MAC address, and there is no address in the
4965  environment, the SROM's address is used.
4966
4967o If there is no valid address in the SROM, and a definition in the
4968  environment exists, then the value from the environment variable is
4969  used.
4970
4971o If both the SROM and the environment contain a MAC address, and
4972  both addresses are the same, this MAC address is used.
4973
4974o If both the SROM and the environment contain a MAC address, and the
4975  addresses differ, the value from the environment is used and a
4976  warning is printed.
4977
4978o If neither SROM nor the environment contain a MAC address, an error
4979  is raised.
4980
4981If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
4982will be programmed into hardware as part of the initialization process.	 This
4983may be skipped by setting the appropriate 'ethmacskip' environment variable.
4984The naming convention is as follows:
4985"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
4986
4987Image Formats:
4988==============
4989
4990U-Boot is capable of booting (and performing other auxiliary operations on)
4991images in two formats:
4992
4993New uImage format (FIT)
4994-----------------------
4995
4996Flexible and powerful format based on Flattened Image Tree -- FIT (similar
4997to Flattened Device Tree). It allows the use of images with multiple
4998components (several kernels, ramdisks, etc.), with contents protected by
4999SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
5000
5001
5002Old uImage format
5003-----------------
5004
5005Old image format is based on binary files which can be basically anything,
5006preceded by a special header; see the definitions in include/image.h for
5007details; basically, the header defines the following image properties:
5008
5009* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
5010  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
5011  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
5012  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
5013  INTEGRITY).
5014* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
5015  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
5016  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
5017* Compression Type (uncompressed, gzip, bzip2)
5018* Load Address
5019* Entry Point
5020* Image Name
5021* Image Timestamp
5022
5023The header is marked by a special Magic Number, and both the header
5024and the data portions of the image are secured against corruption by
5025CRC32 checksums.
5026
5027
5028Linux Support:
5029==============
5030
5031Although U-Boot should support any OS or standalone application
5032easily, the main focus has always been on Linux during the design of
5033U-Boot.
5034
5035U-Boot includes many features that so far have been part of some
5036special "boot loader" code within the Linux kernel. Also, any
5037"initrd" images to be used are no longer part of one big Linux image;
5038instead, kernel and "initrd" are separate images. This implementation
5039serves several purposes:
5040
5041- the same features can be used for other OS or standalone
5042  applications (for instance: using compressed images to reduce the
5043  Flash memory footprint)
5044
5045- it becomes much easier to port new Linux kernel versions because
5046  lots of low-level, hardware dependent stuff are done by U-Boot
5047
5048- the same Linux kernel image can now be used with different "initrd"
5049  images; of course this also means that different kernel images can
5050  be run with the same "initrd". This makes testing easier (you don't
5051  have to build a new "zImage.initrd" Linux image when you just
5052  change a file in your "initrd"). Also, a field-upgrade of the
5053  software is easier now.
5054
5055
5056Linux HOWTO:
5057============
5058
5059Porting Linux to U-Boot based systems:
5060---------------------------------------
5061
5062U-Boot cannot save you from doing all the necessary modifications to
5063configure the Linux device drivers for use with your target hardware
5064(no, we don't intend to provide a full virtual machine interface to
5065Linux :-).
5066
5067But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
5068
5069Just make sure your machine specific header file (for instance
5070include/asm-ppc/tqm8xx.h) includes the same definition of the Board
5071Information structure as we define in include/asm-<arch>/u-boot.h,
5072and make sure that your definition of IMAP_ADDR uses the same value
5073as your U-Boot configuration in CONFIG_SYS_IMMR.
5074
5075
5076Configuring the Linux kernel:
5077-----------------------------
5078
5079No specific requirements for U-Boot. Make sure you have some root
5080device (initial ramdisk, NFS) for your target system.
5081
5082
5083Building a Linux Image:
5084-----------------------
5085
5086With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5087not used. If you use recent kernel source, a new build target
5088"uImage" will exist which automatically builds an image usable by
5089U-Boot. Most older kernels also have support for a "pImage" target,
5090which was introduced for our predecessor project PPCBoot and uses a
5091100% compatible format.
5092
5093Example:
5094
5095	make TQM850L_config
5096	make oldconfig
5097	make dep
5098	make uImage
5099
5100The "uImage" build target uses a special tool (in 'tools/mkimage') to
5101encapsulate a compressed Linux kernel image with header	 information,
5102CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5103
5104* build a standard "vmlinux" kernel image (in ELF binary format):
5105
5106* convert the kernel into a raw binary image:
5107
5108	${CROSS_COMPILE}-objcopy -O binary \
5109				 -R .note -R .comment \
5110				 -S vmlinux linux.bin
5111
5112* compress the binary image:
5113
5114	gzip -9 linux.bin
5115
5116* package compressed binary image for U-Boot:
5117
5118	mkimage -A ppc -O linux -T kernel -C gzip \
5119		-a 0 -e 0 -n "Linux Kernel Image" \
5120		-d linux.bin.gz uImage
5121
5122
5123The "mkimage" tool can also be used to create ramdisk images for use
5124with U-Boot, either separated from the Linux kernel image, or
5125combined into one file. "mkimage" encapsulates the images with a 64
5126byte header containing information about target architecture,
5127operating system, image type, compression method, entry points, time
5128stamp, CRC32 checksums, etc.
5129
5130"mkimage" can be called in two ways: to verify existing images and
5131print the header information, or to build new images.
5132
5133In the first form (with "-l" option) mkimage lists the information
5134contained in the header of an existing U-Boot image; this includes
5135checksum verification:
5136
5137	tools/mkimage -l image
5138	  -l ==> list image header information
5139
5140The second form (with "-d" option) is used to build a U-Boot image
5141from a "data file" which is used as image payload:
5142
5143	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5144		      -n name -d data_file image
5145	  -A ==> set architecture to 'arch'
5146	  -O ==> set operating system to 'os'
5147	  -T ==> set image type to 'type'
5148	  -C ==> set compression type 'comp'
5149	  -a ==> set load address to 'addr' (hex)
5150	  -e ==> set entry point to 'ep' (hex)
5151	  -n ==> set image name to 'name'
5152	  -d ==> use image data from 'datafile'
5153
5154Right now, all Linux kernels for PowerPC systems use the same load
5155address (0x00000000), but the entry point address depends on the
5156kernel version:
5157
5158- 2.2.x kernels have the entry point at 0x0000000C,
5159- 2.3.x and later kernels have the entry point at 0x00000000.
5160
5161So a typical call to build a U-Boot image would read:
5162
5163	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5164	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5165	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5166	> examples/uImage.TQM850L
5167	Image Name:   2.4.4 kernel for TQM850L
5168	Created:      Wed Jul 19 02:34:59 2000
5169	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5170	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5171	Load Address: 0x00000000
5172	Entry Point:  0x00000000
5173
5174To verify the contents of the image (or check for corruption):
5175
5176	-> tools/mkimage -l examples/uImage.TQM850L
5177	Image Name:   2.4.4 kernel for TQM850L
5178	Created:      Wed Jul 19 02:34:59 2000
5179	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5180	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5181	Load Address: 0x00000000
5182	Entry Point:  0x00000000
5183
5184NOTE: for embedded systems where boot time is critical you can trade
5185speed for memory and install an UNCOMPRESSED image instead: this
5186needs more space in Flash, but boots much faster since it does not
5187need to be uncompressed:
5188
5189	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5190	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5191	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5192	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5193	> examples/uImage.TQM850L-uncompressed
5194	Image Name:   2.4.4 kernel for TQM850L
5195	Created:      Wed Jul 19 02:34:59 2000
5196	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5197	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5198	Load Address: 0x00000000
5199	Entry Point:  0x00000000
5200
5201
5202Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5203when your kernel is intended to use an initial ramdisk:
5204
5205	-> tools/mkimage -n 'Simple Ramdisk Image' \
5206	> -A ppc -O linux -T ramdisk -C gzip \
5207	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5208	Image Name:   Simple Ramdisk Image
5209	Created:      Wed Jan 12 14:01:50 2000
5210	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5211	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5212	Load Address: 0x00000000
5213	Entry Point:  0x00000000
5214
5215
5216Installing a Linux Image:
5217-------------------------
5218
5219To downloading a U-Boot image over the serial (console) interface,
5220you must convert the image to S-Record format:
5221
5222	objcopy -I binary -O srec examples/image examples/image.srec
5223
5224The 'objcopy' does not understand the information in the U-Boot
5225image header, so the resulting S-Record file will be relative to
5226address 0x00000000. To load it to a given address, you need to
5227specify the target address as 'offset' parameter with the 'loads'
5228command.
5229
5230Example: install the image to address 0x40100000 (which on the
5231TQM8xxL is in the first Flash bank):
5232
5233	=> erase 40100000 401FFFFF
5234
5235	.......... done
5236	Erased 8 sectors
5237
5238	=> loads 40100000
5239	## Ready for S-Record download ...
5240	~>examples/image.srec
5241	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5242	...
5243	15989 15990 15991 15992
5244	[file transfer complete]
5245	[connected]
5246	## Start Addr = 0x00000000
5247
5248
5249You can check the success of the download using the 'iminfo' command;
5250this includes a checksum verification so you can be sure no data
5251corruption happened:
5252
5253	=> imi 40100000
5254
5255	## Checking Image at 40100000 ...
5256	   Image Name:	 2.2.13 for initrd on TQM850L
5257	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5258	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5259	   Load Address: 00000000
5260	   Entry Point:	 0000000c
5261	   Verifying Checksum ... OK
5262
5263
5264Boot Linux:
5265-----------
5266
5267The "bootm" command is used to boot an application that is stored in
5268memory (RAM or Flash). In case of a Linux kernel image, the contents
5269of the "bootargs" environment variable is passed to the kernel as
5270parameters. You can check and modify this variable using the
5271"printenv" and "setenv" commands:
5272
5273
5274	=> printenv bootargs
5275	bootargs=root=/dev/ram
5276
5277	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5278
5279	=> printenv bootargs
5280	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5281
5282	=> bootm 40020000
5283	## Booting Linux kernel at 40020000 ...
5284	   Image Name:	 2.2.13 for NFS on TQM850L
5285	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5286	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5287	   Load Address: 00000000
5288	   Entry Point:	 0000000c
5289	   Verifying Checksum ... OK
5290	   Uncompressing Kernel Image ... OK
5291	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
5292	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5293	time_init: decrementer frequency = 187500000/60
5294	Calibrating delay loop... 49.77 BogoMIPS
5295	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5296	...
5297
5298If you want to boot a Linux kernel with initial RAM disk, you pass
5299the memory addresses of both the kernel and the initrd image (PPBCOOT
5300format!) to the "bootm" command:
5301
5302	=> imi 40100000 40200000
5303
5304	## Checking Image at 40100000 ...
5305	   Image Name:	 2.2.13 for initrd on TQM850L
5306	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5307	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5308	   Load Address: 00000000
5309	   Entry Point:	 0000000c
5310	   Verifying Checksum ... OK
5311
5312	## Checking Image at 40200000 ...
5313	   Image Name:	 Simple Ramdisk Image
5314	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5315	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5316	   Load Address: 00000000
5317	   Entry Point:	 00000000
5318	   Verifying Checksum ... OK
5319
5320	=> bootm 40100000 40200000
5321	## Booting Linux kernel at 40100000 ...
5322	   Image Name:	 2.2.13 for initrd on TQM850L
5323	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5324	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5325	   Load Address: 00000000
5326	   Entry Point:	 0000000c
5327	   Verifying Checksum ... OK
5328	   Uncompressing Kernel Image ... OK
5329	## Loading RAMDisk Image at 40200000 ...
5330	   Image Name:	 Simple Ramdisk Image
5331	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5332	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5333	   Load Address: 00000000
5334	   Entry Point:	 00000000
5335	   Verifying Checksum ... OK
5336	   Loading Ramdisk ... OK
5337	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
5338	Boot arguments: root=/dev/ram
5339	time_init: decrementer frequency = 187500000/60
5340	Calibrating delay loop... 49.77 BogoMIPS
5341	...
5342	RAMDISK: Compressed image found at block 0
5343	VFS: Mounted root (ext2 filesystem).
5344
5345	bash#
5346
5347Boot Linux and pass a flat device tree:
5348-----------
5349
5350First, U-Boot must be compiled with the appropriate defines. See the section
5351titled "Linux Kernel Interface" above for a more in depth explanation. The
5352following is an example of how to start a kernel and pass an updated
5353flat device tree:
5354
5355=> print oftaddr
5356oftaddr=0x300000
5357=> print oft
5358oft=oftrees/mpc8540ads.dtb
5359=> tftp $oftaddr $oft
5360Speed: 1000, full duplex
5361Using TSEC0 device
5362TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5363Filename 'oftrees/mpc8540ads.dtb'.
5364Load address: 0x300000
5365Loading: #
5366done
5367Bytes transferred = 4106 (100a hex)
5368=> tftp $loadaddr $bootfile
5369Speed: 1000, full duplex
5370Using TSEC0 device
5371TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5372Filename 'uImage'.
5373Load address: 0x200000
5374Loading:############
5375done
5376Bytes transferred = 1029407 (fb51f hex)
5377=> print loadaddr
5378loadaddr=200000
5379=> print oftaddr
5380oftaddr=0x300000
5381=> bootm $loadaddr - $oftaddr
5382## Booting image at 00200000 ...
5383   Image Name:	 Linux-2.6.17-dirty
5384   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5385   Data Size:	 1029343 Bytes = 1005.2 kB
5386   Load Address: 00000000
5387   Entry Point:	 00000000
5388   Verifying Checksum ... OK
5389   Uncompressing Kernel Image ... OK
5390Booting using flat device tree at 0x300000
5391Using MPC85xx ADS machine description
5392Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5393[snip]
5394
5395
5396More About U-Boot Image Types:
5397------------------------------
5398
5399U-Boot supports the following image types:
5400
5401   "Standalone Programs" are directly runnable in the environment
5402	provided by U-Boot; it is expected that (if they behave
5403	well) you can continue to work in U-Boot after return from
5404	the Standalone Program.
5405   "OS Kernel Images" are usually images of some Embedded OS which
5406	will take over control completely. Usually these programs
5407	will install their own set of exception handlers, device
5408	drivers, set up the MMU, etc. - this means, that you cannot
5409	expect to re-enter U-Boot except by resetting the CPU.
5410   "RAMDisk Images" are more or less just data blocks, and their
5411	parameters (address, size) are passed to an OS kernel that is
5412	being started.
5413   "Multi-File Images" contain several images, typically an OS
5414	(Linux) kernel image and one or more data images like
5415	RAMDisks. This construct is useful for instance when you want
5416	to boot over the network using BOOTP etc., where the boot
5417	server provides just a single image file, but you want to get
5418	for instance an OS kernel and a RAMDisk image.
5419
5420	"Multi-File Images" start with a list of image sizes, each
5421	image size (in bytes) specified by an "uint32_t" in network
5422	byte order. This list is terminated by an "(uint32_t)0".
5423	Immediately after the terminating 0 follow the images, one by
5424	one, all aligned on "uint32_t" boundaries (size rounded up to
5425	a multiple of 4 bytes).
5426
5427   "Firmware Images" are binary images containing firmware (like
5428	U-Boot or FPGA images) which usually will be programmed to
5429	flash memory.
5430
5431   "Script files" are command sequences that will be executed by
5432	U-Boot's command interpreter; this feature is especially
5433	useful when you configure U-Boot to use a real shell (hush)
5434	as command interpreter.
5435
5436Booting the Linux zImage:
5437-------------------------
5438
5439On some platforms, it's possible to boot Linux zImage. This is done
5440using the "bootz" command. The syntax of "bootz" command is the same
5441as the syntax of "bootm" command.
5442
5443Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5444kernel with raw initrd images. The syntax is slightly different, the
5445address of the initrd must be augmented by it's size, in the following
5446format: "<initrd addres>:<initrd size>".
5447
5448
5449Standalone HOWTO:
5450=================
5451
5452One of the features of U-Boot is that you can dynamically load and
5453run "standalone" applications, which can use some resources of
5454U-Boot like console I/O functions or interrupt services.
5455
5456Two simple examples are included with the sources:
5457
5458"Hello World" Demo:
5459-------------------
5460
5461'examples/hello_world.c' contains a small "Hello World" Demo
5462application; it is automatically compiled when you build U-Boot.
5463It's configured to run at address 0x00040004, so you can play with it
5464like that:
5465
5466	=> loads
5467	## Ready for S-Record download ...
5468	~>examples/hello_world.srec
5469	1 2 3 4 5 6 7 8 9 10 11 ...
5470	[file transfer complete]
5471	[connected]
5472	## Start Addr = 0x00040004
5473
5474	=> go 40004 Hello World! This is a test.
5475	## Starting application at 0x00040004 ...
5476	Hello World
5477	argc = 7
5478	argv[0] = "40004"
5479	argv[1] = "Hello"
5480	argv[2] = "World!"
5481	argv[3] = "This"
5482	argv[4] = "is"
5483	argv[5] = "a"
5484	argv[6] = "test."
5485	argv[7] = "<NULL>"
5486	Hit any key to exit ...
5487
5488	## Application terminated, rc = 0x0
5489
5490Another example, which demonstrates how to register a CPM interrupt
5491handler with the U-Boot code, can be found in 'examples/timer.c'.
5492Here, a CPM timer is set up to generate an interrupt every second.
5493The interrupt service routine is trivial, just printing a '.'
5494character, but this is just a demo program. The application can be
5495controlled by the following keys:
5496
5497	? - print current values og the CPM Timer registers
5498	b - enable interrupts and start timer
5499	e - stop timer and disable interrupts
5500	q - quit application
5501
5502	=> loads
5503	## Ready for S-Record download ...
5504	~>examples/timer.srec
5505	1 2 3 4 5 6 7 8 9 10 11 ...
5506	[file transfer complete]
5507	[connected]
5508	## Start Addr = 0x00040004
5509
5510	=> go 40004
5511	## Starting application at 0x00040004 ...
5512	TIMERS=0xfff00980
5513	Using timer 1
5514	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5515
5516Hit 'b':
5517	[q, b, e, ?] Set interval 1000000 us
5518	Enabling timer
5519Hit '?':
5520	[q, b, e, ?] ........
5521	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5522Hit '?':
5523	[q, b, e, ?] .
5524	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5525Hit '?':
5526	[q, b, e, ?] .
5527	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
5528Hit '?':
5529	[q, b, e, ?] .
5530	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
5531Hit 'e':
5532	[q, b, e, ?] ...Stopping timer
5533Hit 'q':
5534	[q, b, e, ?] ## Application terminated, rc = 0x0
5535
5536
5537Minicom warning:
5538================
5539
5540Over time, many people have reported problems when trying to use the
5541"minicom" terminal emulation program for serial download. I (wd)
5542consider minicom to be broken, and recommend not to use it. Under
5543Unix, I recommend to use C-Kermit for general purpose use (and
5544especially for kermit binary protocol download ("loadb" command), and
5545use "cu" for S-Record download ("loads" command).  See
5546http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
5547for help with kermit.
5548
5549
5550Nevertheless, if you absolutely want to use it try adding this
5551configuration to your "File transfer protocols" section:
5552
5553	   Name	   Program			Name U/D FullScr IO-Red. Multi
5554	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5555	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5556
5557
5558NetBSD Notes:
5559=============
5560
5561Starting at version 0.9.2, U-Boot supports NetBSD both as host
5562(build U-Boot) and target system (boots NetBSD/mpc8xx).
5563
5564Building requires a cross environment; it is known to work on
5565NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5566need gmake since the Makefiles are not compatible with BSD make).
5567Note that the cross-powerpc package does not install include files;
5568attempting to build U-Boot will fail because <machine/ansi.h> is
5569missing.  This file has to be installed and patched manually:
5570
5571	# cd /usr/pkg/cross/powerpc-netbsd/include
5572	# mkdir powerpc
5573	# ln -s powerpc machine
5574	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5575	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5576
5577Native builds *don't* work due to incompatibilities between native
5578and U-Boot include files.
5579
5580Booting assumes that (the first part of) the image booted is a
5581stage-2 loader which in turn loads and then invokes the kernel
5582proper. Loader sources will eventually appear in the NetBSD source
5583tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5584meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5585
5586
5587Implementation Internals:
5588=========================
5589
5590The following is not intended to be a complete description of every
5591implementation detail. However, it should help to understand the
5592inner workings of U-Boot and make it easier to port it to custom
5593hardware.
5594
5595
5596Initial Stack, Global Data:
5597---------------------------
5598
5599The implementation of U-Boot is complicated by the fact that U-Boot
5600starts running out of ROM (flash memory), usually without access to
5601system RAM (because the memory controller is not initialized yet).
5602This means that we don't have writable Data or BSS segments, and BSS
5603is not initialized as zero. To be able to get a C environment working
5604at all, we have to allocate at least a minimal stack. Implementation
5605options for this are defined and restricted by the CPU used: Some CPU
5606models provide on-chip memory (like the IMMR area on MPC8xx and
5607MPC826x processors), on others (parts of) the data cache can be
5608locked as (mis-) used as memory, etc.
5609
5610	Chris Hallinan posted a good summary of these issues to the
5611	U-Boot mailing list:
5612
5613	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
5614	From: "Chris Hallinan" <clh@net1plus.com>
5615	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
5616	...
5617
5618	Correct me if I'm wrong, folks, but the way I understand it
5619	is this: Using DCACHE as initial RAM for Stack, etc, does not
5620	require any physical RAM backing up the cache. The cleverness
5621	is that the cache is being used as a temporary supply of
5622	necessary storage before the SDRAM controller is setup. It's
5623	beyond the scope of this list to explain the details, but you
5624	can see how this works by studying the cache architecture and
5625	operation in the architecture and processor-specific manuals.
5626
5627	OCM is On Chip Memory, which I believe the 405GP has 4K. It
5628	is another option for the system designer to use as an
5629	initial stack/RAM area prior to SDRAM being available. Either
5630	option should work for you. Using CS 4 should be fine if your
5631	board designers haven't used it for something that would
5632	cause you grief during the initial boot! It is frequently not
5633	used.
5634
5635	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
5636	with your processor/board/system design. The default value
5637	you will find in any recent u-boot distribution in
5638	walnut.h should work for you. I'd set it to a value larger
5639	than your SDRAM module. If you have a 64MB SDRAM module, set
5640	it above 400_0000. Just make sure your board has no resources
5641	that are supposed to respond to that address! That code in
5642	start.S has been around a while and should work as is when
5643	you get the config right.
5644
5645	-Chris Hallinan
5646	DS4.COM, Inc.
5647
5648It is essential to remember this, since it has some impact on the C
5649code for the initialization procedures:
5650
5651* Initialized global data (data segment) is read-only. Do not attempt
5652  to write it.
5653
5654* Do not use any uninitialized global data (or implicitely initialized
5655  as zero data - BSS segment) at all - this is undefined, initiali-
5656  zation is performed later (when relocating to RAM).
5657
5658* Stack space is very limited. Avoid big data buffers or things like
5659  that.
5660
5661Having only the stack as writable memory limits means we cannot use
5662normal global data to share information beween the code. But it
5663turned out that the implementation of U-Boot can be greatly
5664simplified by making a global data structure (gd_t) available to all
5665functions. We could pass a pointer to this data as argument to _all_
5666functions, but this would bloat the code. Instead we use a feature of
5667the GCC compiler (Global Register Variables) to share the data: we
5668place a pointer (gd) to the global data into a register which we
5669reserve for this purpose.
5670
5671When choosing a register for such a purpose we are restricted by the
5672relevant  (E)ABI  specifications for the current architecture, and by
5673GCC's implementation.
5674
5675For PowerPC, the following registers have specific use:
5676	R1:	stack pointer
5677	R2:	reserved for system use
5678	R3-R4:	parameter passing and return values
5679	R5-R10: parameter passing
5680	R13:	small data area pointer
5681	R30:	GOT pointer
5682	R31:	frame pointer
5683
5684	(U-Boot also uses R12 as internal GOT pointer. r12
5685	is a volatile register so r12 needs to be reset when
5686	going back and forth between asm and C)
5687
5688    ==> U-Boot will use R2 to hold a pointer to the global data
5689
5690    Note: on PPC, we could use a static initializer (since the
5691    address of the global data structure is known at compile time),
5692    but it turned out that reserving a register results in somewhat
5693    smaller code - although the code savings are not that big (on
5694    average for all boards 752 bytes for the whole U-Boot image,
5695    624 text + 127 data).
5696
5697On Blackfin, the normal C ABI (except for P3) is followed as documented here:
5698	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
5699
5700    ==> U-Boot will use P3 to hold a pointer to the global data
5701
5702On ARM, the following registers are used:
5703
5704	R0:	function argument word/integer result
5705	R1-R3:	function argument word
5706	R9:	platform specific
5707	R10:	stack limit (used only if stack checking is enabled)
5708	R11:	argument (frame) pointer
5709	R12:	temporary workspace
5710	R13:	stack pointer
5711	R14:	link register
5712	R15:	program counter
5713
5714    ==> U-Boot will use R9 to hold a pointer to the global data
5715
5716    Note: on ARM, only R_ARM_RELATIVE relocations are supported.
5717
5718On Nios II, the ABI is documented here:
5719	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
5720
5721    ==> U-Boot will use gp to hold a pointer to the global data
5722
5723    Note: on Nios II, we give "-G0" option to gcc and don't use gp
5724    to access small data sections, so gp is free.
5725
5726On NDS32, the following registers are used:
5727
5728	R0-R1:	argument/return
5729	R2-R5:	argument
5730	R15:	temporary register for assembler
5731	R16:	trampoline register
5732	R28:	frame pointer (FP)
5733	R29:	global pointer (GP)
5734	R30:	link register (LP)
5735	R31:	stack pointer (SP)
5736	PC:	program counter (PC)
5737
5738    ==> U-Boot will use R10 to hold a pointer to the global data
5739
5740NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
5741or current versions of GCC may "optimize" the code too much.
5742
5743Memory Management:
5744------------------
5745
5746U-Boot runs in system state and uses physical addresses, i.e. the
5747MMU is not used either for address mapping nor for memory protection.
5748
5749The available memory is mapped to fixed addresses using the memory
5750controller. In this process, a contiguous block is formed for each
5751memory type (Flash, SDRAM, SRAM), even when it consists of several
5752physical memory banks.
5753
5754U-Boot is installed in the first 128 kB of the first Flash bank (on
5755TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
5756booting and sizing and initializing DRAM, the code relocates itself
5757to the upper end of DRAM. Immediately below the U-Boot code some
5758memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
5759configuration setting]. Below that, a structure with global Board
5760Info data is placed, followed by the stack (growing downward).
5761
5762Additionally, some exception handler code is copied to the low 8 kB
5763of DRAM (0x00000000 ... 0x00001FFF).
5764
5765So a typical memory configuration with 16 MB of DRAM could look like
5766this:
5767
5768	0x0000 0000	Exception Vector code
5769	      :
5770	0x0000 1FFF
5771	0x0000 2000	Free for Application Use
5772	      :
5773	      :
5774
5775	      :
5776	      :
5777	0x00FB FF20	Monitor Stack (Growing downward)
5778	0x00FB FFAC	Board Info Data and permanent copy of global data
5779	0x00FC 0000	Malloc Arena
5780	      :
5781	0x00FD FFFF
5782	0x00FE 0000	RAM Copy of Monitor Code
5783	...		eventually: LCD or video framebuffer
5784	...		eventually: pRAM (Protected RAM - unchanged by reset)
5785	0x00FF FFFF	[End of RAM]
5786
5787
5788System Initialization:
5789----------------------
5790
5791In the reset configuration, U-Boot starts at the reset entry point
5792(on most PowerPC systems at address 0x00000100). Because of the reset
5793configuration for CS0# this is a mirror of the onboard Flash memory.
5794To be able to re-map memory U-Boot then jumps to its link address.
5795To be able to implement the initialization code in C, a (small!)
5796initial stack is set up in the internal Dual Ported RAM (in case CPUs
5797which provide such a feature like MPC8xx or MPC8260), or in a locked
5798part of the data cache. After that, U-Boot initializes the CPU core,
5799the caches and the SIU.
5800
5801Next, all (potentially) available memory banks are mapped using a
5802preliminary mapping. For example, we put them on 512 MB boundaries
5803(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
5804on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
5805programmed for SDRAM access. Using the temporary configuration, a
5806simple memory test is run that determines the size of the SDRAM
5807banks.
5808
5809When there is more than one SDRAM bank, and the banks are of
5810different size, the largest is mapped first. For equal size, the first
5811bank (CS2#) is mapped first. The first mapping is always for address
58120x00000000, with any additional banks following immediately to create
5813contiguous memory starting from 0.
5814
5815Then, the monitor installs itself at the upper end of the SDRAM area
5816and allocates memory for use by malloc() and for the global Board
5817Info data; also, the exception vector code is copied to the low RAM
5818pages, and the final stack is set up.
5819
5820Only after this relocation will you have a "normal" C environment;
5821until that you are restricted in several ways, mostly because you are
5822running from ROM, and because the code will have to be relocated to a
5823new address in RAM.
5824
5825
5826U-Boot Porting Guide:
5827----------------------
5828
5829[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
5830list, October 2002]
5831
5832
5833int main(int argc, char *argv[])
5834{
5835	sighandler_t no_more_time;
5836
5837	signal(SIGALRM, no_more_time);
5838	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
5839
5840	if (available_money > available_manpower) {
5841		Pay consultant to port U-Boot;
5842		return 0;
5843	}
5844
5845	Download latest U-Boot source;
5846
5847	Subscribe to u-boot mailing list;
5848
5849	if (clueless)
5850		email("Hi, I am new to U-Boot, how do I get started?");
5851
5852	while (learning) {
5853		Read the README file in the top level directory;
5854		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
5855		Read applicable doc/*.README;
5856		Read the source, Luke;
5857		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
5858	}
5859
5860	if (available_money > toLocalCurrency ($2500))
5861		Buy a BDI3000;
5862	else
5863		Add a lot of aggravation and time;
5864
5865	if (a similar board exists) {	/* hopefully... */
5866		cp -a board/<similar> board/<myboard>
5867		cp include/configs/<similar>.h include/configs/<myboard>.h
5868	} else {
5869		Create your own board support subdirectory;
5870		Create your own board include/configs/<myboard>.h file;
5871	}
5872	Edit new board/<myboard> files
5873	Edit new include/configs/<myboard>.h
5874
5875	while (!accepted) {
5876		while (!running) {
5877			do {
5878				Add / modify source code;
5879			} until (compiles);
5880			Debug;
5881			if (clueless)
5882				email("Hi, I am having problems...");
5883		}
5884		Send patch file to the U-Boot email list;
5885		if (reasonable critiques)
5886			Incorporate improvements from email list code review;
5887		else
5888			Defend code as written;
5889	}
5890
5891	return 0;
5892}
5893
5894void no_more_time (int sig)
5895{
5896      hire_a_guru();
5897}
5898
5899
5900Coding Standards:
5901-----------------
5902
5903All contributions to U-Boot should conform to the Linux kernel
5904coding style; see the file "Documentation/CodingStyle" and the script
5905"scripts/Lindent" in your Linux kernel source directory.
5906
5907Source files originating from a different project (for example the
5908MTD subsystem) are generally exempt from these guidelines and are not
5909reformated to ease subsequent migration to newer versions of those
5910sources.
5911
5912Please note that U-Boot is implemented in C (and to some small parts in
5913Assembler); no C++ is used, so please do not use C++ style comments (//)
5914in your code.
5915
5916Please also stick to the following formatting rules:
5917- remove any trailing white space
5918- use TAB characters for indentation and vertical alignment, not spaces
5919- make sure NOT to use DOS '\r\n' line feeds
5920- do not add more than 2 consecutive empty lines to source files
5921- do not add trailing empty lines to source files
5922
5923Submissions which do not conform to the standards may be returned
5924with a request to reformat the changes.
5925
5926
5927Submitting Patches:
5928-------------------
5929
5930Since the number of patches for U-Boot is growing, we need to
5931establish some rules. Submissions which do not conform to these rules
5932may be rejected, even when they contain important and valuable stuff.
5933
5934Please see http://www.denx.de/wiki/U-Boot/Patches for details.
5935
5936Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
5937see http://lists.denx.de/mailman/listinfo/u-boot
5938
5939When you send a patch, please include the following information with
5940it:
5941
5942* For bug fixes: a description of the bug and how your patch fixes
5943  this bug. Please try to include a way of demonstrating that the
5944  patch actually fixes something.
5945
5946* For new features: a description of the feature and your
5947  implementation.
5948
5949* A CHANGELOG entry as plaintext (separate from the patch)
5950
5951* For major contributions, your entry to the CREDITS file
5952
5953* When you add support for a new board, don't forget to add a
5954  maintainer e-mail address to the boards.cfg file, too.
5955
5956* If your patch adds new configuration options, don't forget to
5957  document these in the README file.
5958
5959* The patch itself. If you are using git (which is *strongly*
5960  recommended) you can easily generate the patch using the
5961  "git format-patch". If you then use "git send-email" to send it to
5962  the U-Boot mailing list, you will avoid most of the common problems
5963  with some other mail clients.
5964
5965  If you cannot use git, use "diff -purN OLD NEW". If your version of
5966  diff does not support these options, then get the latest version of
5967  GNU diff.
5968
5969  The current directory when running this command shall be the parent
5970  directory of the U-Boot source tree (i. e. please make sure that
5971  your patch includes sufficient directory information for the
5972  affected files).
5973
5974  We prefer patches as plain text. MIME attachments are discouraged,
5975  and compressed attachments must not be used.
5976
5977* If one logical set of modifications affects or creates several
5978  files, all these changes shall be submitted in a SINGLE patch file.
5979
5980* Changesets that contain different, unrelated modifications shall be
5981  submitted as SEPARATE patches, one patch per changeset.
5982
5983
5984Notes:
5985
5986* Before sending the patch, run the MAKEALL script on your patched
5987  source tree and make sure that no errors or warnings are reported
5988  for any of the boards.
5989
5990* Keep your modifications to the necessary minimum: A patch
5991  containing several unrelated changes or arbitrary reformats will be
5992  returned with a request to re-formatting / split it.
5993
5994* If you modify existing code, make sure that your new code does not
5995  add to the memory footprint of the code ;-) Small is beautiful!
5996  When adding new features, these should compile conditionally only
5997  (using #ifdef), and the resulting code with the new feature
5998  disabled must not need more memory than the old code without your
5999  modification.
6000
6001* Remember that there is a size limit of 100 kB per message on the
6002  u-boot mailing list. Bigger patches will be moderated. If they are
6003  reasonable and not too big, they will be acknowledged. But patches
6004  bigger than the size limit should be avoided.
6005