xref: /openbmc/u-boot/README (revision 25b26ec6)
1#
2# (C) Copyright 2000 - 2012
3# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
4#
5# See file CREDITS for list of people who contributed to this
6# project.
7#
8# This program is free software; you can redistribute it and/or
9# modify it under the terms of the GNU General Public License as
10# published by the Free Software Foundation; either version 2 of
11# the License, or (at your option) any later version.
12#
13# This program is distributed in the hope that it will be useful,
14# but WITHOUT ANY WARRANTY; without even the implied warranty of
15# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	See the
16# GNU General Public License for more details.
17#
18# You should have received a copy of the GNU General Public License
19# along with this program; if not, write to the Free Software
20# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
21# MA 02111-1307 USA
22#
23
24Summary:
25========
26
27This directory contains the source code for U-Boot, a boot loader for
28Embedded boards based on PowerPC, ARM, MIPS and several other
29processors, which can be installed in a boot ROM and used to
30initialize and test the hardware or to download and run application
31code.
32
33The development of U-Boot is closely related to Linux: some parts of
34the source code originate in the Linux source tree, we have some
35header files in common, and special provision has been made to
36support booting of Linux images.
37
38Some attention has been paid to make this software easily
39configurable and extendable. For instance, all monitor commands are
40implemented with the same call interface, so that it's very easy to
41add new commands. Also, instead of permanently adding rarely used
42code (for instance hardware test utilities) to the monitor, you can
43load and run it dynamically.
44
45
46Status:
47=======
48
49In general, all boards for which a configuration option exists in the
50Makefile have been tested to some extent and can be considered
51"working". In fact, many of them are used in production systems.
52
53In case of problems see the CHANGELOG and CREDITS files to find out
54who contributed the specific port. The MAINTAINERS file lists board
55maintainers.
56
57
58Where to get help:
59==================
60
61In case you have questions about, problems with or contributions for
62U-Boot you should send a message to the U-Boot mailing list at
63<u-boot@lists.denx.de>. There is also an archive of previous traffic
64on the mailing list - please search the archive before asking FAQ's.
65Please see http://lists.denx.de/pipermail/u-boot and
66http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
67
68
69Where to get source code:
70=========================
71
72The U-Boot source code is maintained in the git repository at
73git://www.denx.de/git/u-boot.git ; you can browse it online at
74http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
75
76The "snapshot" links on this page allow you to download tarballs of
77any version you might be interested in. Official releases are also
78available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
79directory.
80
81Pre-built (and tested) images are available from
82ftp://ftp.denx.de/pub/u-boot/images/
83
84
85Where we come from:
86===================
87
88- start from 8xxrom sources
89- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
90- clean up code
91- make it easier to add custom boards
92- make it possible to add other [PowerPC] CPUs
93- extend functions, especially:
94  * Provide extended interface to Linux boot loader
95  * S-Record download
96  * network boot
97  * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
98- create ARMBoot project (http://sourceforge.net/projects/armboot)
99- add other CPU families (starting with ARM)
100- create U-Boot project (http://sourceforge.net/projects/u-boot)
101- current project page: see http://www.denx.de/wiki/U-Boot
102
103
104Names and Spelling:
105===================
106
107The "official" name of this project is "Das U-Boot". The spelling
108"U-Boot" shall be used in all written text (documentation, comments
109in source files etc.). Example:
110
111	This is the README file for the U-Boot project.
112
113File names etc. shall be based on the string "u-boot". Examples:
114
115	include/asm-ppc/u-boot.h
116
117	#include <asm/u-boot.h>
118
119Variable names, preprocessor constants etc. shall be either based on
120the string "u_boot" or on "U_BOOT". Example:
121
122	U_BOOT_VERSION		u_boot_logo
123	IH_OS_U_BOOT		u_boot_hush_start
124
125
126Versioning:
127===========
128
129Starting with the release in October 2008, the names of the releases
130were changed from numerical release numbers without deeper meaning
131into a time stamp based numbering. Regular releases are identified by
132names consisting of the calendar year and month of the release date.
133Additional fields (if present) indicate release candidates or bug fix
134releases in "stable" maintenance trees.
135
136Examples:
137	U-Boot v2009.11	    - Release November 2009
138	U-Boot v2009.11.1   - Release 1 in version November 2009 stable tree
139	U-Boot v2010.09-rc1 - Release candiate 1 for September 2010 release
140
141
142Directory Hierarchy:
143====================
144
145/arch			Architecture specific files
146  /arm			Files generic to ARM architecture
147    /cpu		CPU specific files
148      /arm720t		Files specific to ARM 720 CPUs
149      /arm920t		Files specific to ARM 920 CPUs
150	/at91		Files specific to Atmel AT91RM9200 CPU
151	/imx		Files specific to Freescale MC9328 i.MX CPUs
152	/s3c24x0	Files specific to Samsung S3C24X0 CPUs
153      /arm925t		Files specific to ARM 925 CPUs
154      /arm926ejs	Files specific to ARM 926 CPUs
155      /arm1136		Files specific to ARM 1136 CPUs
156      /ixp		Files specific to Intel XScale IXP CPUs
157      /pxa		Files specific to Intel XScale PXA CPUs
158      /s3c44b0		Files specific to Samsung S3C44B0 CPUs
159      /sa1100		Files specific to Intel StrongARM SA1100 CPUs
160    /lib		Architecture specific library files
161  /avr32		Files generic to AVR32 architecture
162    /cpu		CPU specific files
163    /lib		Architecture specific library files
164  /blackfin		Files generic to Analog Devices Blackfin architecture
165    /cpu		CPU specific files
166    /lib		Architecture specific library files
167  /x86			Files generic to x86 architecture
168    /cpu		CPU specific files
169    /lib		Architecture specific library files
170  /m68k			Files generic to m68k architecture
171    /cpu		CPU specific files
172      /mcf52x2		Files specific to Freescale ColdFire MCF52x2 CPUs
173      /mcf5227x		Files specific to Freescale ColdFire MCF5227x CPUs
174      /mcf532x		Files specific to Freescale ColdFire MCF5329 CPUs
175      /mcf5445x		Files specific to Freescale ColdFire MCF5445x CPUs
176      /mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
177    /lib		Architecture specific library files
178  /microblaze		Files generic to microblaze architecture
179    /cpu		CPU specific files
180    /lib		Architecture specific library files
181  /mips			Files generic to MIPS architecture
182    /cpu		CPU specific files
183      /mips32		Files specific to MIPS32 CPUs
184      /xburst		Files specific to Ingenic XBurst CPUs
185    /lib		Architecture specific library files
186  /nds32		Files generic to NDS32 architecture
187    /cpu		CPU specific files
188      /n1213		Files specific to Andes Technology N1213 CPUs
189    /lib		Architecture specific library files
190  /nios2		Files generic to Altera NIOS2 architecture
191    /cpu		CPU specific files
192    /lib		Architecture specific library files
193  /powerpc		Files generic to PowerPC architecture
194    /cpu		CPU specific files
195      /74xx_7xx		Files specific to Freescale MPC74xx and 7xx CPUs
196      /mpc5xx		Files specific to Freescale MPC5xx CPUs
197      /mpc5xxx		Files specific to Freescale MPC5xxx CPUs
198      /mpc8xx		Files specific to Freescale MPC8xx CPUs
199      /mpc8220		Files specific to Freescale MPC8220 CPUs
200      /mpc824x		Files specific to Freescale MPC824x CPUs
201      /mpc8260		Files specific to Freescale MPC8260 CPUs
202      /mpc85xx		Files specific to Freescale MPC85xx CPUs
203      /ppc4xx		Files specific to AMCC PowerPC 4xx CPUs
204    /lib		Architecture specific library files
205  /sh			Files generic to SH architecture
206    /cpu		CPU specific files
207      /sh2		Files specific to sh2 CPUs
208      /sh3		Files specific to sh3 CPUs
209      /sh4		Files specific to sh4 CPUs
210    /lib		Architecture specific library files
211  /sparc		Files generic to SPARC architecture
212    /cpu		CPU specific files
213      /leon2		Files specific to Gaisler LEON2 SPARC CPU
214      /leon3		Files specific to Gaisler LEON3 SPARC CPU
215    /lib		Architecture specific library files
216/api			Machine/arch independent API for external apps
217/board			Board dependent files
218/common			Misc architecture independent functions
219/disk			Code for disk drive partition handling
220/doc			Documentation (don't expect too much)
221/drivers		Commonly used device drivers
222/examples		Example code for standalone applications, etc.
223/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
224/include		Header Files
225/lib			Files generic to all architectures
226  /libfdt		Library files to support flattened device trees
227  /lzma			Library files to support LZMA decompression
228  /lzo			Library files to support LZO decompression
229/net			Networking code
230/post			Power On Self Test
231/rtc			Real Time Clock drivers
232/tools			Tools to build S-Record or U-Boot images, etc.
233
234Software Configuration:
235=======================
236
237Configuration is usually done using C preprocessor defines; the
238rationale behind that is to avoid dead code whenever possible.
239
240There are two classes of configuration variables:
241
242* Configuration _OPTIONS_:
243  These are selectable by the user and have names beginning with
244  "CONFIG_".
245
246* Configuration _SETTINGS_:
247  These depend on the hardware etc. and should not be meddled with if
248  you don't know what you're doing; they have names beginning with
249  "CONFIG_SYS_".
250
251Later we will add a configuration tool - probably similar to or even
252identical to what's used for the Linux kernel. Right now, we have to
253do the configuration by hand, which means creating some symbolic
254links and editing some configuration files. We use the TQM8xxL boards
255as an example here.
256
257
258Selection of Processor Architecture and Board Type:
259---------------------------------------------------
260
261For all supported boards there are ready-to-use default
262configurations available; just type "make <board_name>_config".
263
264Example: For a TQM823L module type:
265
266	cd u-boot
267	make TQM823L_config
268
269For the Cogent platform, you need to specify the CPU type as well;
270e.g. "make cogent_mpc8xx_config". And also configure the cogent
271directory according to the instructions in cogent/README.
272
273
274Configuration Options:
275----------------------
276
277Configuration depends on the combination of board and CPU type; all
278such information is kept in a configuration file
279"include/configs/<board_name>.h".
280
281Example: For a TQM823L module, all configuration settings are in
282"include/configs/TQM823L.h".
283
284
285Many of the options are named exactly as the corresponding Linux
286kernel configuration options. The intention is to make it easier to
287build a config tool - later.
288
289
290The following options need to be configured:
291
292- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
293
294- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
295
296- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
297		Define exactly one, e.g. CONFIG_ATSTK1002
298
299- CPU Module Type: (if CONFIG_COGENT is defined)
300		Define exactly one of
301		CONFIG_CMA286_60_OLD
302--- FIXME --- not tested yet:
303		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
304		CONFIG_CMA287_23, CONFIG_CMA287_50
305
306- Motherboard Type: (if CONFIG_COGENT is defined)
307		Define exactly one of
308		CONFIG_CMA101, CONFIG_CMA102
309
310- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
311		Define one or more of
312		CONFIG_CMA302
313
314- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
315		Define one or more of
316		CONFIG_LCD_HEARTBEAT	- update a character position on
317					  the LCD display every second with
318					  a "rotator" |\-/|\-/
319
320- Board flavour: (if CONFIG_MPC8260ADS is defined)
321		CONFIG_ADSTYPE
322		Possible values are:
323			CONFIG_SYS_8260ADS	- original MPC8260ADS
324			CONFIG_SYS_8266ADS	- MPC8266ADS
325			CONFIG_SYS_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
326			CONFIG_SYS_8272ADS	- MPC8272ADS
327
328- Marvell Family Member
329		CONFIG_SYS_MVFS		- define it if you want to enable
330					  multiple fs option at one time
331					  for marvell soc family
332
333- MPC824X Family Member (if CONFIG_MPC824X is defined)
334		Define exactly one of
335		CONFIG_MPC8240, CONFIG_MPC8245
336
337- 8xx CPU Options: (if using an MPC8xx CPU)
338		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
339					  get_gclk_freq() cannot work
340					  e.g. if there is no 32KHz
341					  reference PIT/RTC clock
342		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
343					  or XTAL/EXTAL)
344
345- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
346		CONFIG_SYS_8xx_CPUCLK_MIN
347		CONFIG_SYS_8xx_CPUCLK_MAX
348		CONFIG_8xx_CPUCLK_DEFAULT
349			See doc/README.MPC866
350
351		CONFIG_SYS_MEASURE_CPUCLK
352
353		Define this to measure the actual CPU clock instead
354		of relying on the correctness of the configured
355		values. Mostly useful for board bringup to make sure
356		the PLL is locked at the intended frequency. Note
357		that this requires a (stable) reference clock (32 kHz
358		RTC clock or CONFIG_SYS_8XX_XIN)
359
360		CONFIG_SYS_DELAYED_ICACHE
361
362		Define this option if you want to enable the
363		ICache only when Code runs from RAM.
364
365- 85xx CPU Options:
366		CONFIG_SYS_PPC64
367
368		Specifies that the core is a 64-bit PowerPC implementation (implements
369		the "64" category of the Power ISA). This is necessary for ePAPR
370		compliance, among other possible reasons.
371
372		CONFIG_SYS_FSL_TBCLK_DIV
373
374		Defines the core time base clock divider ratio compared to the
375		system clock.  On most PQ3 devices this is 8, on newer QorIQ
376		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
377
378		CONFIG_SYS_FSL_PCIE_COMPAT
379
380		Defines the string to utilize when trying to match PCIe device
381		tree nodes for the given platform.
382
383		CONFIG_SYS_PPC_E500_DEBUG_TLB
384
385		Enables a temporary TLB entry to be used during boot to work
386		around limitations in e500v1 and e500v2 external debugger
387		support. This reduces the portions of the boot code where
388		breakpoints and single stepping do not work.  The value of this
389		symbol should be set to the TLB1 entry to be used for this
390		purpose.
391
392		CONFIG_SYS_FSL_ERRATUM_A004510
393
394		Enables a workaround for erratum A004510.  If set,
395		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
396		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
397
398		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
399		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
400
401		Defines one or two SoC revisions (low 8 bits of SVR)
402		for which the A004510 workaround should be applied.
403
404		The rest of SVR is either not relevant to the decision
405		of whether the erratum is present (e.g. p2040 versus
406		p2041) or is implied by the build target, which controls
407		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
408
409		See Freescale App Note 4493 for more information about
410		this erratum.
411
412		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
413
414		This is the value to write into CCSR offset 0x18600
415		according to the A004510 workaround.
416
417- Generic CPU options:
418		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
419
420		Defines the endianess of the CPU. Implementation of those
421		values is arch specific.
422
423- Intel Monahans options:
424		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
425
426		Defines the Monahans run mode to oscillator
427		ratio. Valid values are 8, 16, 24, 31. The core
428		frequency is this value multiplied by 13 MHz.
429
430		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
431
432		Defines the Monahans turbo mode to oscillator
433		ratio. Valid values are 1 (default if undefined) and
434		2. The core frequency as calculated above is multiplied
435		by this value.
436
437- MIPS CPU options:
438		CONFIG_SYS_INIT_SP_OFFSET
439
440		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
441		pointer. This is needed for the temporary stack before
442		relocation.
443
444		CONFIG_SYS_MIPS_CACHE_MODE
445
446		Cache operation mode for the MIPS CPU.
447		See also arch/mips/include/asm/mipsregs.h.
448		Possible values are:
449			CONF_CM_CACHABLE_NO_WA
450			CONF_CM_CACHABLE_WA
451			CONF_CM_UNCACHED
452			CONF_CM_CACHABLE_NONCOHERENT
453			CONF_CM_CACHABLE_CE
454			CONF_CM_CACHABLE_COW
455			CONF_CM_CACHABLE_CUW
456			CONF_CM_CACHABLE_ACCELERATED
457
458		CONFIG_SYS_XWAY_EBU_BOOTCFG
459
460		Special option for Lantiq XWAY SoCs for booting from NOR flash.
461		See also arch/mips/cpu/mips32/start.S.
462
463		CONFIG_XWAY_SWAP_BYTES
464
465		Enable compilation of tools/xway-swap-bytes needed for Lantiq
466		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
467		be swapped if a flash programmer is used.
468
469- ARM options:
470		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
471
472		Select high exception vectors of the ARM core, e.g., do not
473		clear the V bit of the c1 register of CP15.
474
475		CONFIG_SYS_THUMB_BUILD
476
477		Use this flag to build U-Boot using the Thumb instruction
478		set for ARM architectures. Thumb instruction set provides
479		better code density. For ARM architectures that support
480		Thumb2 this flag will result in Thumb2 code generated by
481		GCC.
482
483- Linux Kernel Interface:
484		CONFIG_CLOCKS_IN_MHZ
485
486		U-Boot stores all clock information in Hz
487		internally. For binary compatibility with older Linux
488		kernels (which expect the clocks passed in the
489		bd_info data to be in MHz) the environment variable
490		"clocks_in_mhz" can be defined so that U-Boot
491		converts clock data to MHZ before passing it to the
492		Linux kernel.
493		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
494		"clocks_in_mhz=1" is automatically included in the
495		default environment.
496
497		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
498
499		When transferring memsize parameter to linux, some versions
500		expect it to be in bytes, others in MB.
501		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
502
503		CONFIG_OF_LIBFDT
504
505		New kernel versions are expecting firmware settings to be
506		passed using flattened device trees (based on open firmware
507		concepts).
508
509		CONFIG_OF_LIBFDT
510		 * New libfdt-based support
511		 * Adds the "fdt" command
512		 * The bootm command automatically updates the fdt
513
514		OF_CPU - The proper name of the cpus node (only required for
515			MPC512X and MPC5xxx based boards).
516		OF_SOC - The proper name of the soc node (only required for
517			MPC512X and MPC5xxx based boards).
518		OF_TBCLK - The timebase frequency.
519		OF_STDOUT_PATH - The path to the console device
520
521		boards with QUICC Engines require OF_QE to set UCC MAC
522		addresses
523
524		CONFIG_OF_BOARD_SETUP
525
526		Board code has addition modification that it wants to make
527		to the flat device tree before handing it off to the kernel
528
529		CONFIG_OF_BOOT_CPU
530
531		This define fills in the correct boot CPU in the boot
532		param header, the default value is zero if undefined.
533
534		CONFIG_OF_IDE_FIXUP
535
536		U-Boot can detect if an IDE device is present or not.
537		If not, and this new config option is activated, U-Boot
538		removes the ATA node from the DTS before booting Linux,
539		so the Linux IDE driver does not probe the device and
540		crash. This is needed for buggy hardware (uc101) where
541		no pull down resistor is connected to the signal IDE5V_DD7.
542
543		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
544
545		This setting is mandatory for all boards that have only one
546		machine type and must be used to specify the machine type
547		number as it appears in the ARM machine registry
548		(see http://www.arm.linux.org.uk/developer/machines/).
549		Only boards that have multiple machine types supported
550		in a single configuration file and the machine type is
551		runtime discoverable, do not have to use this setting.
552
553- vxWorks boot parameters:
554
555		bootvx constructs a valid bootline using the following
556		environments variables: bootfile, ipaddr, serverip, hostname.
557		It loads the vxWorks image pointed bootfile.
558
559		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
560		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
561		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
562		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
563
564		CONFIG_SYS_VXWORKS_ADD_PARAMS
565
566		Add it at the end of the bootline. E.g "u=username pw=secret"
567
568		Note: If a "bootargs" environment is defined, it will overwride
569		the defaults discussed just above.
570
571- Cache Configuration:
572		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
573		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
574		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
575
576- Cache Configuration for ARM:
577		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
578				      controller
579		CONFIG_SYS_PL310_BASE - Physical base address of PL310
580					controller register space
581
582- Serial Ports:
583		CONFIG_PL010_SERIAL
584
585		Define this if you want support for Amba PrimeCell PL010 UARTs.
586
587		CONFIG_PL011_SERIAL
588
589		Define this if you want support for Amba PrimeCell PL011 UARTs.
590
591		CONFIG_PL011_CLOCK
592
593		If you have Amba PrimeCell PL011 UARTs, set this variable to
594		the clock speed of the UARTs.
595
596		CONFIG_PL01x_PORTS
597
598		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
599		define this to a list of base addresses for each (supported)
600		port. See e.g. include/configs/versatile.h
601
602		CONFIG_PL011_SERIAL_RLCR
603
604		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
605		have separate receive and transmit line control registers.  Set
606		this variable to initialize the extra register.
607
608		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
609
610		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
611		boot loader that has already initialized the UART.  Define this
612		variable to flush the UART at init time.
613
614
615- Console Interface:
616		Depending on board, define exactly one serial port
617		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
618		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
619		console by defining CONFIG_8xx_CONS_NONE
620
621		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
622		port routines must be defined elsewhere
623		(i.e. serial_init(), serial_getc(), ...)
624
625		CONFIG_CFB_CONSOLE
626		Enables console device for a color framebuffer. Needs following
627		defines (cf. smiLynxEM, i8042)
628			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
629						(default big endian)
630			VIDEO_HW_RECTFILL	graphic chip supports
631						rectangle fill
632						(cf. smiLynxEM)
633			VIDEO_HW_BITBLT		graphic chip supports
634						bit-blit (cf. smiLynxEM)
635			VIDEO_VISIBLE_COLS	visible pixel columns
636						(cols=pitch)
637			VIDEO_VISIBLE_ROWS	visible pixel rows
638			VIDEO_PIXEL_SIZE	bytes per pixel
639			VIDEO_DATA_FORMAT	graphic data format
640						(0-5, cf. cfb_console.c)
641			VIDEO_FB_ADRS		framebuffer address
642			VIDEO_KBD_INIT_FCT	keyboard int fct
643						(i.e. i8042_kbd_init())
644			VIDEO_TSTC_FCT		test char fct
645						(i.e. i8042_tstc)
646			VIDEO_GETC_FCT		get char fct
647						(i.e. i8042_getc)
648			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
649						(requires blink timer
650						cf. i8042.c)
651			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
652			CONFIG_CONSOLE_TIME	display time/date info in
653						upper right corner
654						(requires CONFIG_CMD_DATE)
655			CONFIG_VIDEO_LOGO	display Linux logo in
656						upper left corner
657			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
658						linux_logo.h for logo.
659						Requires CONFIG_VIDEO_LOGO
660			CONFIG_CONSOLE_EXTRA_INFO
661						additional board info beside
662						the logo
663
664		When CONFIG_CFB_CONSOLE is defined, video console is
665		default i/o. Serial console can be forced with
666		environment 'console=serial'.
667
668		When CONFIG_SILENT_CONSOLE is defined, all console
669		messages (by U-Boot and Linux!) can be silenced with
670		the "silent" environment variable. See
671		doc/README.silent for more information.
672
673- Console Baudrate:
674		CONFIG_BAUDRATE - in bps
675		Select one of the baudrates listed in
676		CONFIG_SYS_BAUDRATE_TABLE, see below.
677		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
678
679- Console Rx buffer length
680		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
681		the maximum receive buffer length for the SMC.
682		This option is actual only for 82xx and 8xx possible.
683		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
684		must be defined, to setup the maximum idle timeout for
685		the SMC.
686
687- Pre-Console Buffer:
688		Prior to the console being initialised (i.e. serial UART
689		initialised etc) all console output is silently discarded.
690		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
691		buffer any console messages prior to the console being
692		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
693		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
694		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
695		bytes are output before the console is initialised, the
696		earlier bytes are discarded.
697
698		'Sane' compilers will generate smaller code if
699		CONFIG_PRE_CON_BUF_SZ is a power of 2
700
701- Safe printf() functions
702		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
703		the printf() functions. These are defined in
704		include/vsprintf.h and include snprintf(), vsnprintf() and
705		so on. Code size increase is approximately 300-500 bytes.
706		If this option is not given then these functions will
707		silently discard their buffer size argument - this means
708		you are not getting any overflow checking in this case.
709
710- Boot Delay:	CONFIG_BOOTDELAY - in seconds
711		Delay before automatically booting the default image;
712		set to -1 to disable autoboot.
713		set to -2 to autoboot with no delay and not check for abort
714		(even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).
715
716		See doc/README.autoboot for these options that
717		work with CONFIG_BOOTDELAY. None are required.
718		CONFIG_BOOT_RETRY_TIME
719		CONFIG_BOOT_RETRY_MIN
720		CONFIG_AUTOBOOT_KEYED
721		CONFIG_AUTOBOOT_PROMPT
722		CONFIG_AUTOBOOT_DELAY_STR
723		CONFIG_AUTOBOOT_STOP_STR
724		CONFIG_AUTOBOOT_DELAY_STR2
725		CONFIG_AUTOBOOT_STOP_STR2
726		CONFIG_ZERO_BOOTDELAY_CHECK
727		CONFIG_RESET_TO_RETRY
728
729- Autoboot Command:
730		CONFIG_BOOTCOMMAND
731		Only needed when CONFIG_BOOTDELAY is enabled;
732		define a command string that is automatically executed
733		when no character is read on the console interface
734		within "Boot Delay" after reset.
735
736		CONFIG_BOOTARGS
737		This can be used to pass arguments to the bootm
738		command. The value of CONFIG_BOOTARGS goes into the
739		environment value "bootargs".
740
741		CONFIG_RAMBOOT and CONFIG_NFSBOOT
742		The value of these goes into the environment as
743		"ramboot" and "nfsboot" respectively, and can be used
744		as a convenience, when switching between booting from
745		RAM and NFS.
746
747- Pre-Boot Commands:
748		CONFIG_PREBOOT
749
750		When this option is #defined, the existence of the
751		environment variable "preboot" will be checked
752		immediately before starting the CONFIG_BOOTDELAY
753		countdown and/or running the auto-boot command resp.
754		entering interactive mode.
755
756		This feature is especially useful when "preboot" is
757		automatically generated or modified. For an example
758		see the LWMON board specific code: here "preboot" is
759		modified when the user holds down a certain
760		combination of keys on the (special) keyboard when
761		booting the systems
762
763- Serial Download Echo Mode:
764		CONFIG_LOADS_ECHO
765		If defined to 1, all characters received during a
766		serial download (using the "loads" command) are
767		echoed back. This might be needed by some terminal
768		emulations (like "cu"), but may as well just take
769		time on others. This setting #define's the initial
770		value of the "loads_echo" environment variable.
771
772- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
773		CONFIG_KGDB_BAUDRATE
774		Select one of the baudrates listed in
775		CONFIG_SYS_BAUDRATE_TABLE, see below.
776
777- Monitor Functions:
778		Monitor commands can be included or excluded
779		from the build by using the #include files
780		<config_cmd_all.h> and #undef'ing unwanted
781		commands, or using <config_cmd_default.h>
782		and augmenting with additional #define's
783		for wanted commands.
784
785		The default command configuration includes all commands
786		except those marked below with a "*".
787
788		CONFIG_CMD_ASKENV	* ask for env variable
789		CONFIG_CMD_BDI		  bdinfo
790		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
791		CONFIG_CMD_BMP		* BMP support
792		CONFIG_CMD_BSP		* Board specific commands
793		CONFIG_CMD_BOOTD	  bootd
794		CONFIG_CMD_CACHE	* icache, dcache
795		CONFIG_CMD_CONSOLE	  coninfo
796		CONFIG_CMD_CRC32	* crc32
797		CONFIG_CMD_DATE		* support for RTC, date/time...
798		CONFIG_CMD_DHCP		* DHCP support
799		CONFIG_CMD_DIAG		* Diagnostics
800		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
801		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
802		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
803		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
804		CONFIG_CMD_DTT		* Digital Therm and Thermostat
805		CONFIG_CMD_ECHO		  echo arguments
806		CONFIG_CMD_EDITENV	  edit env variable
807		CONFIG_CMD_EEPROM	* EEPROM read/write support
808		CONFIG_CMD_ELF		* bootelf, bootvx
809		CONFIG_CMD_EXPORTENV	* export the environment
810		CONFIG_CMD_EXT2		* ext2 command support
811		CONFIG_CMD_EXT4		* ext4 command support
812		CONFIG_CMD_SAVEENV	  saveenv
813		CONFIG_CMD_FDC		* Floppy Disk Support
814		CONFIG_CMD_FAT		* FAT command support
815		CONFIG_CMD_FDOS		* Dos diskette Support
816		CONFIG_CMD_FLASH	  flinfo, erase, protect
817		CONFIG_CMD_FPGA		  FPGA device initialization support
818		CONFIG_CMD_GO		* the 'go' command (exec code)
819		CONFIG_CMD_GREPENV	* search environment
820		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
821		CONFIG_CMD_I2C		* I2C serial bus support
822		CONFIG_CMD_IDE		* IDE harddisk support
823		CONFIG_CMD_IMI		  iminfo
824		CONFIG_CMD_IMLS		  List all found images
825		CONFIG_CMD_IMMAP	* IMMR dump support
826		CONFIG_CMD_IMPORTENV	* import an environment
827		CONFIG_CMD_INI		* import data from an ini file into the env
828		CONFIG_CMD_IRQ		* irqinfo
829		CONFIG_CMD_ITEST	  Integer/string test of 2 values
830		CONFIG_CMD_JFFS2	* JFFS2 Support
831		CONFIG_CMD_KGDB		* kgdb
832		CONFIG_CMD_LDRINFO	  ldrinfo (display Blackfin loader)
833		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
834					  (169.254.*.*)
835		CONFIG_CMD_LOADB	  loadb
836		CONFIG_CMD_LOADS	  loads
837		CONFIG_CMD_MD5SUM	  print md5 message digest
838					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
839		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
840					  loop, loopw, mtest
841		CONFIG_CMD_MISC		  Misc functions like sleep etc
842		CONFIG_CMD_MMC		* MMC memory mapped support
843		CONFIG_CMD_MII		* MII utility commands
844		CONFIG_CMD_MTDPARTS	* MTD partition support
845		CONFIG_CMD_NAND		* NAND support
846		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
847		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
848		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
849		CONFIG_CMD_PCI		* pciinfo
850		CONFIG_CMD_PCMCIA		* PCMCIA support
851		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
852					  host
853		CONFIG_CMD_PORTIO	* Port I/O
854		CONFIG_CMD_REGINFO	* Register dump
855		CONFIG_CMD_RUN		  run command in env variable
856		CONFIG_CMD_SAVES	* save S record dump
857		CONFIG_CMD_SCSI		* SCSI Support
858		CONFIG_CMD_SDRAM	* print SDRAM configuration information
859					  (requires CONFIG_CMD_I2C)
860		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
861					  (4xx only)
862		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
863		CONFIG_CMD_SHA1SUM	  print sha1 memory digest
864					  (requires CONFIG_CMD_MEMORY)
865		CONFIG_CMD_SOURCE	  "source" command Support
866		CONFIG_CMD_SPI		* SPI serial bus support
867		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
868		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
869		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
870		CONFIG_CMD_TIMER	* access to the system tick timer
871		CONFIG_CMD_USB		* USB support
872		CONFIG_CMD_CDP		* Cisco Discover Protocol support
873		CONFIG_CMD_MFSL		* Microblaze FSL support
874
875
876		EXAMPLE: If you want all functions except of network
877		support you can write:
878
879		#include "config_cmd_all.h"
880		#undef CONFIG_CMD_NET
881
882	Other Commands:
883		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
884
885	Note:	Don't enable the "icache" and "dcache" commands
886		(configuration option CONFIG_CMD_CACHE) unless you know
887		what you (and your U-Boot users) are doing. Data
888		cache cannot be enabled on systems like the 8xx or
889		8260 (where accesses to the IMMR region must be
890		uncached), and it cannot be disabled on all other
891		systems where we (mis-) use the data cache to hold an
892		initial stack and some data.
893
894
895		XXX - this list needs to get updated!
896
897- Device tree:
898		CONFIG_OF_CONTROL
899		If this variable is defined, U-Boot will use a device tree
900		to configure its devices, instead of relying on statically
901		compiled #defines in the board file. This option is
902		experimental and only available on a few boards. The device
903		tree is available in the global data as gd->fdt_blob.
904
905		U-Boot needs to get its device tree from somewhere. This can
906		be done using one of the two options below:
907
908		CONFIG_OF_EMBED
909		If this variable is defined, U-Boot will embed a device tree
910		binary in its image. This device tree file should be in the
911		board directory and called <soc>-<board>.dts. The binary file
912		is then picked up in board_init_f() and made available through
913		the global data structure as gd->blob.
914
915		CONFIG_OF_SEPARATE
916		If this variable is defined, U-Boot will build a device tree
917		binary. It will be called u-boot.dtb. Architecture-specific
918		code will locate it at run-time. Generally this works by:
919
920			cat u-boot.bin u-boot.dtb >image.bin
921
922		and in fact, U-Boot does this for you, creating a file called
923		u-boot-dtb.bin which is useful in the common case. You can
924		still use the individual files if you need something more
925		exotic.
926
927- Watchdog:
928		CONFIG_WATCHDOG
929		If this variable is defined, it enables watchdog
930		support for the SoC. There must be support in the SoC
931		specific code for a watchdog. For the 8xx and 8260
932		CPUs, the SIU Watchdog feature is enabled in the SYPCR
933		register.  When supported for a specific SoC is
934		available, then no further board specific code should
935		be needed to use it.
936
937		CONFIG_HW_WATCHDOG
938		When using a watchdog circuitry external to the used
939		SoC, then define this variable and provide board
940		specific code for the "hw_watchdog_reset" function.
941
942- U-Boot Version:
943		CONFIG_VERSION_VARIABLE
944		If this variable is defined, an environment variable
945		named "ver" is created by U-Boot showing the U-Boot
946		version as printed by the "version" command.
947		Any change to this variable will be reverted at the
948		next reset.
949
950- Real-Time Clock:
951
952		When CONFIG_CMD_DATE is selected, the type of the RTC
953		has to be selected, too. Define exactly one of the
954		following options:
955
956		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
957		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
958		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
959		CONFIG_RTC_MC146818	- use MC146818 RTC
960		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
961		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
962		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
963		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
964		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
965		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
966		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
967		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
968					  RV3029 RTC.
969
970		Note that if the RTC uses I2C, then the I2C interface
971		must also be configured. See I2C Support, below.
972
973- GPIO Support:
974		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
975		CONFIG_PCA953X_INFO	- enable pca953x info command
976
977		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
978		chip-ngpio pairs that tell the PCA953X driver the number of
979		pins supported by a particular chip.
980
981		Note that if the GPIO device uses I2C, then the I2C interface
982		must also be configured. See I2C Support, below.
983
984- Timestamp Support:
985
986		When CONFIG_TIMESTAMP is selected, the timestamp
987		(date and time) of an image is printed by image
988		commands like bootm or iminfo. This option is
989		automatically enabled when you select CONFIG_CMD_DATE .
990
991- Partition Labels (disklabels) Supported:
992		Zero or more of the following:
993		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
994		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
995				       Intel architecture, USB sticks, etc.
996		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
997		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
998				       bootloader.  Note 2TB partition limit; see
999				       disk/part_efi.c
1000		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1001
1002		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1003		CONFIG_CMD_SCSI) you must configure support for at
1004		least one non-MTD partition type as well.
1005
1006- IDE Reset method:
1007		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1008		board configurations files but used nowhere!
1009
1010		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1011		be performed by calling the function
1012			ide_set_reset(int reset)
1013		which has to be defined in a board specific file
1014
1015- ATAPI Support:
1016		CONFIG_ATAPI
1017
1018		Set this to enable ATAPI support.
1019
1020- LBA48 Support
1021		CONFIG_LBA48
1022
1023		Set this to enable support for disks larger than 137GB
1024		Also look at CONFIG_SYS_64BIT_LBA.
1025		Whithout these , LBA48 support uses 32bit variables and will 'only'
1026		support disks up to 2.1TB.
1027
1028		CONFIG_SYS_64BIT_LBA:
1029			When enabled, makes the IDE subsystem use 64bit sector addresses.
1030			Default is 32bit.
1031
1032- SCSI Support:
1033		At the moment only there is only support for the
1034		SYM53C8XX SCSI controller; define
1035		CONFIG_SCSI_SYM53C8XX to enable it.
1036
1037		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1038		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1039		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1040		maximum numbers of LUNs, SCSI ID's and target
1041		devices.
1042		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1043
1044                The environment variable 'scsidevs' is set to the number of
1045                SCSI devices found during the last scan.
1046
1047- NETWORK Support (PCI):
1048		CONFIG_E1000
1049		Support for Intel 8254x/8257x gigabit chips.
1050
1051		CONFIG_E1000_SPI
1052		Utility code for direct access to the SPI bus on Intel 8257x.
1053		This does not do anything useful unless you set at least one
1054		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1055
1056		CONFIG_E1000_SPI_GENERIC
1057		Allow generic access to the SPI bus on the Intel 8257x, for
1058		example with the "sspi" command.
1059
1060		CONFIG_CMD_E1000
1061		Management command for E1000 devices.  When used on devices
1062		with SPI support you can reprogram the EEPROM from U-Boot.
1063
1064		CONFIG_E1000_FALLBACK_MAC
1065		default MAC for empty EEPROM after production.
1066
1067		CONFIG_EEPRO100
1068		Support for Intel 82557/82559/82559ER chips.
1069		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1070		write routine for first time initialisation.
1071
1072		CONFIG_TULIP
1073		Support for Digital 2114x chips.
1074		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1075		modem chip initialisation (KS8761/QS6611).
1076
1077		CONFIG_NATSEMI
1078		Support for National dp83815 chips.
1079
1080		CONFIG_NS8382X
1081		Support for National dp8382[01] gigabit chips.
1082
1083- NETWORK Support (other):
1084
1085		CONFIG_DRIVER_AT91EMAC
1086		Support for AT91RM9200 EMAC.
1087
1088			CONFIG_RMII
1089			Define this to use reduced MII inteface
1090
1091			CONFIG_DRIVER_AT91EMAC_QUIET
1092			If this defined, the driver is quiet.
1093			The driver doen't show link status messages.
1094
1095		CONFIG_CALXEDA_XGMAC
1096		Support for the Calxeda XGMAC device
1097
1098		CONFIG_LAN91C96
1099		Support for SMSC's LAN91C96 chips.
1100
1101			CONFIG_LAN91C96_BASE
1102			Define this to hold the physical address
1103			of the LAN91C96's I/O space
1104
1105			CONFIG_LAN91C96_USE_32_BIT
1106			Define this to enable 32 bit addressing
1107
1108		CONFIG_SMC91111
1109		Support for SMSC's LAN91C111 chip
1110
1111			CONFIG_SMC91111_BASE
1112			Define this to hold the physical address
1113			of the device (I/O space)
1114
1115			CONFIG_SMC_USE_32_BIT
1116			Define this if data bus is 32 bits
1117
1118			CONFIG_SMC_USE_IOFUNCS
1119			Define this to use i/o functions instead of macros
1120			(some hardware wont work with macros)
1121
1122		CONFIG_DRIVER_TI_EMAC
1123		Support for davinci emac
1124
1125			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1126			Define this if you have more then 3 PHYs.
1127
1128		CONFIG_FTGMAC100
1129		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1130
1131			CONFIG_FTGMAC100_EGIGA
1132			Define this to use GE link update with gigabit PHY.
1133			Define this if FTGMAC100 is connected to gigabit PHY.
1134			If your system has 10/100 PHY only, it might not occur
1135			wrong behavior. Because PHY usually return timeout or
1136			useless data when polling gigabit status and gigabit
1137			control registers. This behavior won't affect the
1138			correctnessof 10/100 link speed update.
1139
1140		CONFIG_SMC911X
1141		Support for SMSC's LAN911x and LAN921x chips
1142
1143			CONFIG_SMC911X_BASE
1144			Define this to hold the physical address
1145			of the device (I/O space)
1146
1147			CONFIG_SMC911X_32_BIT
1148			Define this if data bus is 32 bits
1149
1150			CONFIG_SMC911X_16_BIT
1151			Define this if data bus is 16 bits. If your processor
1152			automatically converts one 32 bit word to two 16 bit
1153			words you may also try CONFIG_SMC911X_32_BIT.
1154
1155		CONFIG_SH_ETHER
1156		Support for Renesas on-chip Ethernet controller
1157
1158			CONFIG_SH_ETHER_USE_PORT
1159			Define the number of ports to be used
1160
1161			CONFIG_SH_ETHER_PHY_ADDR
1162			Define the ETH PHY's address
1163
1164			CONFIG_SH_ETHER_CACHE_WRITEBACK
1165			If this option is set, the driver enables cache flush.
1166
1167- TPM Support:
1168		CONFIG_GENERIC_LPC_TPM
1169		Support for generic parallel port TPM devices. Only one device
1170		per system is supported at this time.
1171
1172			CONFIG_TPM_TIS_BASE_ADDRESS
1173			Base address where the generic TPM device is mapped
1174			to. Contemporary x86 systems usually map it at
1175			0xfed40000.
1176
1177- USB Support:
1178		At the moment only the UHCI host controller is
1179		supported (PIP405, MIP405, MPC5200); define
1180		CONFIG_USB_UHCI to enable it.
1181		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1182		and define CONFIG_USB_STORAGE to enable the USB
1183		storage devices.
1184		Note:
1185		Supported are USB Keyboards and USB Floppy drives
1186		(TEAC FD-05PUB).
1187		MPC5200 USB requires additional defines:
1188			CONFIG_USB_CLOCK
1189				for 528 MHz Clock: 0x0001bbbb
1190			CONFIG_PSC3_USB
1191				for USB on PSC3
1192			CONFIG_USB_CONFIG
1193				for differential drivers: 0x00001000
1194				for single ended drivers: 0x00005000
1195				for differential drivers on PSC3: 0x00000100
1196				for single ended drivers on PSC3: 0x00004100
1197			CONFIG_SYS_USB_EVENT_POLL
1198				May be defined to allow interrupt polling
1199				instead of using asynchronous interrupts
1200
1201		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1202		txfilltuning field in the EHCI controller on reset.
1203
1204- USB Device:
1205		Define the below if you wish to use the USB console.
1206		Once firmware is rebuilt from a serial console issue the
1207		command "setenv stdin usbtty; setenv stdout usbtty" and
1208		attach your USB cable. The Unix command "dmesg" should print
1209		it has found a new device. The environment variable usbtty
1210		can be set to gserial or cdc_acm to enable your device to
1211		appear to a USB host as a Linux gserial device or a
1212		Common Device Class Abstract Control Model serial device.
1213		If you select usbtty = gserial you should be able to enumerate
1214		a Linux host by
1215		# modprobe usbserial vendor=0xVendorID product=0xProductID
1216		else if using cdc_acm, simply setting the environment
1217		variable usbtty to be cdc_acm should suffice. The following
1218		might be defined in YourBoardName.h
1219
1220			CONFIG_USB_DEVICE
1221			Define this to build a UDC device
1222
1223			CONFIG_USB_TTY
1224			Define this to have a tty type of device available to
1225			talk to the UDC device
1226
1227			CONFIG_USBD_HS
1228			Define this to enable the high speed support for usb
1229			device and usbtty. If this feature is enabled, a routine
1230			int is_usbd_high_speed(void)
1231			also needs to be defined by the driver to dynamically poll
1232			whether the enumeration has succeded at high speed or full
1233			speed.
1234
1235			CONFIG_SYS_CONSOLE_IS_IN_ENV
1236			Define this if you want stdin, stdout &/or stderr to
1237			be set to usbtty.
1238
1239			mpc8xx:
1240				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1241				Derive USB clock from external clock "blah"
1242				- CONFIG_SYS_USB_EXTC_CLK 0x02
1243
1244				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1245				Derive USB clock from brgclk
1246				- CONFIG_SYS_USB_BRG_CLK 0x04
1247
1248		If you have a USB-IF assigned VendorID then you may wish to
1249		define your own vendor specific values either in BoardName.h
1250		or directly in usbd_vendor_info.h. If you don't define
1251		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1252		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1253		should pretend to be a Linux device to it's target host.
1254
1255			CONFIG_USBD_MANUFACTURER
1256			Define this string as the name of your company for
1257			- CONFIG_USBD_MANUFACTURER "my company"
1258
1259			CONFIG_USBD_PRODUCT_NAME
1260			Define this string as the name of your product
1261			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1262
1263			CONFIG_USBD_VENDORID
1264			Define this as your assigned Vendor ID from the USB
1265			Implementors Forum. This *must* be a genuine Vendor ID
1266			to avoid polluting the USB namespace.
1267			- CONFIG_USBD_VENDORID 0xFFFF
1268
1269			CONFIG_USBD_PRODUCTID
1270			Define this as the unique Product ID
1271			for your device
1272			- CONFIG_USBD_PRODUCTID 0xFFFF
1273
1274- ULPI Layer Support:
1275		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1276		the generic ULPI layer. The generic layer accesses the ULPI PHY
1277		via the platform viewport, so you need both the genric layer and
1278		the viewport enabled. Currently only Chipidea/ARC based
1279		viewport is supported.
1280		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1281		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1282		If your ULPI phy needs a different reference clock than the
1283		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1284		the appropriate value in Hz.
1285
1286- MMC Support:
1287		The MMC controller on the Intel PXA is supported. To
1288		enable this define CONFIG_MMC. The MMC can be
1289		accessed from the boot prompt by mapping the device
1290		to physical memory similar to flash. Command line is
1291		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1292		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1293
1294		CONFIG_SH_MMCIF
1295		Support for Renesas on-chip MMCIF controller
1296
1297			CONFIG_SH_MMCIF_ADDR
1298			Define the base address of MMCIF registers
1299
1300			CONFIG_SH_MMCIF_CLK
1301			Define the clock frequency for MMCIF
1302
1303- Journaling Flash filesystem support:
1304		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1305		CONFIG_JFFS2_NAND_DEV
1306		Define these for a default partition on a NAND device
1307
1308		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1309		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1310		Define these for a default partition on a NOR device
1311
1312		CONFIG_SYS_JFFS_CUSTOM_PART
1313		Define this to create an own partition. You have to provide a
1314		function struct part_info* jffs2_part_info(int part_num)
1315
1316		If you define only one JFFS2 partition you may also want to
1317		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1318		to disable the command chpart. This is the default when you
1319		have not defined a custom partition
1320
1321- FAT(File Allocation Table) filesystem write function support:
1322		CONFIG_FAT_WRITE
1323
1324		Define this to enable support for saving memory data as a
1325		file in FAT formatted partition.
1326
1327		This will also enable the command "fatwrite" enabling the
1328		user to write files to FAT.
1329
1330CBFS (Coreboot Filesystem) support
1331		CONFIG_CMD_CBFS
1332
1333		Define this to enable support for reading from a Coreboot
1334		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1335		and cbfsload.
1336
1337- Keyboard Support:
1338		CONFIG_ISA_KEYBOARD
1339
1340		Define this to enable standard (PC-Style) keyboard
1341		support
1342
1343		CONFIG_I8042_KBD
1344		Standard PC keyboard driver with US (is default) and
1345		GERMAN key layout (switch via environment 'keymap=de') support.
1346		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1347		for cfb_console. Supports cursor blinking.
1348
1349- Video support:
1350		CONFIG_VIDEO
1351
1352		Define this to enable video support (for output to
1353		video).
1354
1355		CONFIG_VIDEO_CT69000
1356
1357		Enable Chips & Technologies 69000 Video chip
1358
1359		CONFIG_VIDEO_SMI_LYNXEM
1360		Enable Silicon Motion SMI 712/710/810 Video chip. The
1361		video output is selected via environment 'videoout'
1362		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1363		assumed.
1364
1365		For the CT69000 and SMI_LYNXEM drivers, videomode is
1366		selected via environment 'videomode'. Two different ways
1367		are possible:
1368		- "videomode=num"   'num' is a standard LiLo mode numbers.
1369		Following standard modes are supported	(* is default):
1370
1371		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1372		-------------+---------------------------------------------
1373		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1374		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1375		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1376		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1377		-------------+---------------------------------------------
1378		(i.e. setenv videomode 317; saveenv; reset;)
1379
1380		- "videomode=bootargs" all the video parameters are parsed
1381		from the bootargs. (See drivers/video/videomodes.c)
1382
1383
1384		CONFIG_VIDEO_SED13806
1385		Enable Epson SED13806 driver. This driver supports 8bpp
1386		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1387		or CONFIG_VIDEO_SED13806_16BPP
1388
1389		CONFIG_FSL_DIU_FB
1390		Enable the Freescale DIU video driver.	Reference boards for
1391		SOCs that have a DIU should define this macro to enable DIU
1392		support, and should also define these other macros:
1393
1394			CONFIG_SYS_DIU_ADDR
1395			CONFIG_VIDEO
1396			CONFIG_CMD_BMP
1397			CONFIG_CFB_CONSOLE
1398			CONFIG_VIDEO_SW_CURSOR
1399			CONFIG_VGA_AS_SINGLE_DEVICE
1400			CONFIG_VIDEO_LOGO
1401			CONFIG_VIDEO_BMP_LOGO
1402
1403		The DIU driver will look for the 'video-mode' environment
1404		variable, and if defined, enable the DIU as a console during
1405		boot.  See the documentation file README.video for a
1406		description of this variable.
1407
1408- Keyboard Support:
1409		CONFIG_KEYBOARD
1410
1411		Define this to enable a custom keyboard support.
1412		This simply calls drv_keyboard_init() which must be
1413		defined in your board-specific files.
1414		The only board using this so far is RBC823.
1415
1416- LCD Support:	CONFIG_LCD
1417
1418		Define this to enable LCD support (for output to LCD
1419		display); also select one of the supported displays
1420		by defining one of these:
1421
1422		CONFIG_ATMEL_LCD:
1423
1424			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1425
1426		CONFIG_NEC_NL6448AC33:
1427
1428			NEC NL6448AC33-18. Active, color, single scan.
1429
1430		CONFIG_NEC_NL6448BC20
1431
1432			NEC NL6448BC20-08. 6.5", 640x480.
1433			Active, color, single scan.
1434
1435		CONFIG_NEC_NL6448BC33_54
1436
1437			NEC NL6448BC33-54. 10.4", 640x480.
1438			Active, color, single scan.
1439
1440		CONFIG_SHARP_16x9
1441
1442			Sharp 320x240. Active, color, single scan.
1443			It isn't 16x9, and I am not sure what it is.
1444
1445		CONFIG_SHARP_LQ64D341
1446
1447			Sharp LQ64D341 display, 640x480.
1448			Active, color, single scan.
1449
1450		CONFIG_HLD1045
1451
1452			HLD1045 display, 640x480.
1453			Active, color, single scan.
1454
1455		CONFIG_OPTREX_BW
1456
1457			Optrex	 CBL50840-2 NF-FW 99 22 M5
1458			or
1459			Hitachi	 LMG6912RPFC-00T
1460			or
1461			Hitachi	 SP14Q002
1462
1463			320x240. Black & white.
1464
1465		Normally display is black on white background; define
1466		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1467
1468- Splash Screen Support: CONFIG_SPLASH_SCREEN
1469
1470		If this option is set, the environment is checked for
1471		a variable "splashimage". If found, the usual display
1472		of logo, copyright and system information on the LCD
1473		is suppressed and the BMP image at the address
1474		specified in "splashimage" is loaded instead. The
1475		console is redirected to the "nulldev", too. This
1476		allows for a "silent" boot where a splash screen is
1477		loaded very quickly after power-on.
1478
1479		CONFIG_SPLASH_SCREEN_ALIGN
1480
1481		If this option is set the splash image can be freely positioned
1482		on the screen. Environment variable "splashpos" specifies the
1483		position as "x,y". If a positive number is given it is used as
1484		number of pixel from left/top. If a negative number is given it
1485		is used as number of pixel from right/bottom. You can also
1486		specify 'm' for centering the image.
1487
1488		Example:
1489		setenv splashpos m,m
1490			=> image at center of screen
1491
1492		setenv splashpos 30,20
1493			=> image at x = 30 and y = 20
1494
1495		setenv splashpos -10,m
1496			=> vertically centered image
1497			   at x = dspWidth - bmpWidth - 9
1498
1499- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1500
1501		If this option is set, additionally to standard BMP
1502		images, gzipped BMP images can be displayed via the
1503		splashscreen support or the bmp command.
1504
1505- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1506
1507		If this option is set, 8-bit RLE compressed BMP images
1508		can be displayed via the splashscreen support or the
1509		bmp command.
1510
1511- Do compresssing for memory range:
1512		CONFIG_CMD_ZIP
1513
1514		If this option is set, it would use zlib deflate method
1515		to compress the specified memory at its best effort.
1516
1517- Compression support:
1518		CONFIG_BZIP2
1519
1520		If this option is set, support for bzip2 compressed
1521		images is included. If not, only uncompressed and gzip
1522		compressed images are supported.
1523
1524		NOTE: the bzip2 algorithm requires a lot of RAM, so
1525		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1526		be at least 4MB.
1527
1528		CONFIG_LZMA
1529
1530		If this option is set, support for lzma compressed
1531		images is included.
1532
1533		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1534		requires an amount of dynamic memory that is given by the
1535		formula:
1536
1537			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1538
1539		Where lc and lp stand for, respectively, Literal context bits
1540		and Literal pos bits.
1541
1542		This value is upper-bounded by 14MB in the worst case. Anyway,
1543		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1544		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1545		a very small buffer.
1546
1547		Use the lzmainfo tool to determinate the lc and lp values and
1548		then calculate the amount of needed dynamic memory (ensuring
1549		the appropriate CONFIG_SYS_MALLOC_LEN value).
1550
1551- MII/PHY support:
1552		CONFIG_PHY_ADDR
1553
1554		The address of PHY on MII bus.
1555
1556		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1557
1558		The clock frequency of the MII bus
1559
1560		CONFIG_PHY_GIGE
1561
1562		If this option is set, support for speed/duplex
1563		detection of gigabit PHY is included.
1564
1565		CONFIG_PHY_RESET_DELAY
1566
1567		Some PHY like Intel LXT971A need extra delay after
1568		reset before any MII register access is possible.
1569		For such PHY, set this option to the usec delay
1570		required. (minimum 300usec for LXT971A)
1571
1572		CONFIG_PHY_CMD_DELAY (ppc4xx)
1573
1574		Some PHY like Intel LXT971A need extra delay after
1575		command issued before MII status register can be read
1576
1577- Ethernet address:
1578		CONFIG_ETHADDR
1579		CONFIG_ETH1ADDR
1580		CONFIG_ETH2ADDR
1581		CONFIG_ETH3ADDR
1582		CONFIG_ETH4ADDR
1583		CONFIG_ETH5ADDR
1584
1585		Define a default value for Ethernet address to use
1586		for the respective Ethernet interface, in case this
1587		is not determined automatically.
1588
1589- IP address:
1590		CONFIG_IPADDR
1591
1592		Define a default value for the IP address to use for
1593		the default Ethernet interface, in case this is not
1594		determined through e.g. bootp.
1595		(Environment variable "ipaddr")
1596
1597- Server IP address:
1598		CONFIG_SERVERIP
1599
1600		Defines a default value for the IP address of a TFTP
1601		server to contact when using the "tftboot" command.
1602		(Environment variable "serverip")
1603
1604		CONFIG_KEEP_SERVERADDR
1605
1606		Keeps the server's MAC address, in the env 'serveraddr'
1607		for passing to bootargs (like Linux's netconsole option)
1608
1609- Gateway IP address:
1610		CONFIG_GATEWAYIP
1611
1612		Defines a default value for the IP address of the
1613		default router where packets to other networks are
1614		sent to.
1615		(Environment variable "gatewayip")
1616
1617- Subnet mask:
1618		CONFIG_NETMASK
1619
1620		Defines a default value for the subnet mask (or
1621		routing prefix) which is used to determine if an IP
1622		address belongs to the local subnet or needs to be
1623		forwarded through a router.
1624		(Environment variable "netmask")
1625
1626- Multicast TFTP Mode:
1627		CONFIG_MCAST_TFTP
1628
1629		Defines whether you want to support multicast TFTP as per
1630		rfc-2090; for example to work with atftp.  Lets lots of targets
1631		tftp down the same boot image concurrently.  Note: the Ethernet
1632		driver in use must provide a function: mcast() to join/leave a
1633		multicast group.
1634
1635- BOOTP Recovery Mode:
1636		CONFIG_BOOTP_RANDOM_DELAY
1637
1638		If you have many targets in a network that try to
1639		boot using BOOTP, you may want to avoid that all
1640		systems send out BOOTP requests at precisely the same
1641		moment (which would happen for instance at recovery
1642		from a power failure, when all systems will try to
1643		boot, thus flooding the BOOTP server. Defining
1644		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1645		inserted before sending out BOOTP requests. The
1646		following delays are inserted then:
1647
1648		1st BOOTP request:	delay 0 ... 1 sec
1649		2nd BOOTP request:	delay 0 ... 2 sec
1650		3rd BOOTP request:	delay 0 ... 4 sec
1651		4th and following
1652		BOOTP requests:		delay 0 ... 8 sec
1653
1654- DHCP Advanced Options:
1655		You can fine tune the DHCP functionality by defining
1656		CONFIG_BOOTP_* symbols:
1657
1658		CONFIG_BOOTP_SUBNETMASK
1659		CONFIG_BOOTP_GATEWAY
1660		CONFIG_BOOTP_HOSTNAME
1661		CONFIG_BOOTP_NISDOMAIN
1662		CONFIG_BOOTP_BOOTPATH
1663		CONFIG_BOOTP_BOOTFILESIZE
1664		CONFIG_BOOTP_DNS
1665		CONFIG_BOOTP_DNS2
1666		CONFIG_BOOTP_SEND_HOSTNAME
1667		CONFIG_BOOTP_NTPSERVER
1668		CONFIG_BOOTP_TIMEOFFSET
1669		CONFIG_BOOTP_VENDOREX
1670		CONFIG_BOOTP_MAY_FAIL
1671
1672		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1673		environment variable, not the BOOTP server.
1674
1675		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1676		after the configured retry count, the call will fail
1677		instead of starting over.  This can be used to fail over
1678		to Link-local IP address configuration if the DHCP server
1679		is not available.
1680
1681		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1682		serverip from a DHCP server, it is possible that more
1683		than one DNS serverip is offered to the client.
1684		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1685		serverip will be stored in the additional environment
1686		variable "dnsip2". The first DNS serverip is always
1687		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1688		is defined.
1689
1690		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1691		to do a dynamic update of a DNS server. To do this, they
1692		need the hostname of the DHCP requester.
1693		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1694		of the "hostname" environment variable is passed as
1695		option 12 to the DHCP server.
1696
1697		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1698
1699		A 32bit value in microseconds for a delay between
1700		receiving a "DHCP Offer" and sending the "DHCP Request".
1701		This fixes a problem with certain DHCP servers that don't
1702		respond 100% of the time to a "DHCP request". E.g. On an
1703		AT91RM9200 processor running at 180MHz, this delay needed
1704		to be *at least* 15,000 usec before a Windows Server 2003
1705		DHCP server would reply 100% of the time. I recommend at
1706		least 50,000 usec to be safe. The alternative is to hope
1707		that one of the retries will be successful but note that
1708		the DHCP timeout and retry process takes a longer than
1709		this delay.
1710
1711 - Link-local IP address negotiation:
1712		Negotiate with other link-local clients on the local network
1713		for an address that doesn't require explicit configuration.
1714		This is especially useful if a DHCP server cannot be guaranteed
1715		to exist in all environments that the device must operate.
1716
1717		See doc/README.link-local for more information.
1718
1719 - CDP Options:
1720		CONFIG_CDP_DEVICE_ID
1721
1722		The device id used in CDP trigger frames.
1723
1724		CONFIG_CDP_DEVICE_ID_PREFIX
1725
1726		A two character string which is prefixed to the MAC address
1727		of the device.
1728
1729		CONFIG_CDP_PORT_ID
1730
1731		A printf format string which contains the ascii name of
1732		the port. Normally is set to "eth%d" which sets
1733		eth0 for the first Ethernet, eth1 for the second etc.
1734
1735		CONFIG_CDP_CAPABILITIES
1736
1737		A 32bit integer which indicates the device capabilities;
1738		0x00000010 for a normal host which does not forwards.
1739
1740		CONFIG_CDP_VERSION
1741
1742		An ascii string containing the version of the software.
1743
1744		CONFIG_CDP_PLATFORM
1745
1746		An ascii string containing the name of the platform.
1747
1748		CONFIG_CDP_TRIGGER
1749
1750		A 32bit integer sent on the trigger.
1751
1752		CONFIG_CDP_POWER_CONSUMPTION
1753
1754		A 16bit integer containing the power consumption of the
1755		device in .1 of milliwatts.
1756
1757		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1758
1759		A byte containing the id of the VLAN.
1760
1761- Status LED:	CONFIG_STATUS_LED
1762
1763		Several configurations allow to display the current
1764		status using a LED. For instance, the LED will blink
1765		fast while running U-Boot code, stop blinking as
1766		soon as a reply to a BOOTP request was received, and
1767		start blinking slow once the Linux kernel is running
1768		(supported by a status LED driver in the Linux
1769		kernel). Defining CONFIG_STATUS_LED enables this
1770		feature in U-Boot.
1771
1772- CAN Support:	CONFIG_CAN_DRIVER
1773
1774		Defining CONFIG_CAN_DRIVER enables CAN driver support
1775		on those systems that support this (optional)
1776		feature, like the TQM8xxL modules.
1777
1778- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1779
1780		These enable I2C serial bus commands. Defining either of
1781		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1782		include the appropriate I2C driver for the selected CPU.
1783
1784		This will allow you to use i2c commands at the u-boot
1785		command line (as long as you set CONFIG_CMD_I2C in
1786		CONFIG_COMMANDS) and communicate with i2c based realtime
1787		clock chips. See common/cmd_i2c.c for a description of the
1788		command line interface.
1789
1790		CONFIG_HARD_I2C selects a hardware I2C controller.
1791
1792		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1793		bit-banging) driver instead of CPM or similar hardware
1794		support for I2C.
1795
1796		There are several other quantities that must also be
1797		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1798
1799		In both cases you will need to define CONFIG_SYS_I2C_SPEED
1800		to be the frequency (in Hz) at which you wish your i2c bus
1801		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
1802		the CPU's i2c node address).
1803
1804		Now, the u-boot i2c code for the mpc8xx
1805		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
1806		and so its address should therefore be cleared to 0 (See,
1807		eg, MPC823e User's Manual p.16-473). So, set
1808		CONFIG_SYS_I2C_SLAVE to 0.
1809
1810		CONFIG_SYS_I2C_INIT_MPC5XXX
1811
1812		When a board is reset during an i2c bus transfer
1813		chips might think that the current transfer is still
1814		in progress.  Reset the slave devices by sending start
1815		commands until the slave device responds.
1816
1817		That's all that's required for CONFIG_HARD_I2C.
1818
1819		If you use the software i2c interface (CONFIG_SOFT_I2C)
1820		then the following macros need to be defined (examples are
1821		from include/configs/lwmon.h):
1822
1823		I2C_INIT
1824
1825		(Optional). Any commands necessary to enable the I2C
1826		controller or configure ports.
1827
1828		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
1829
1830		I2C_PORT
1831
1832		(Only for MPC8260 CPU). The I/O port to use (the code
1833		assumes both bits are on the same port). Valid values
1834		are 0..3 for ports A..D.
1835
1836		I2C_ACTIVE
1837
1838		The code necessary to make the I2C data line active
1839		(driven).  If the data line is open collector, this
1840		define can be null.
1841
1842		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1843
1844		I2C_TRISTATE
1845
1846		The code necessary to make the I2C data line tri-stated
1847		(inactive).  If the data line is open collector, this
1848		define can be null.
1849
1850		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1851
1852		I2C_READ
1853
1854		Code that returns TRUE if the I2C data line is high,
1855		FALSE if it is low.
1856
1857		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1858
1859		I2C_SDA(bit)
1860
1861		If <bit> is TRUE, sets the I2C data line high. If it
1862		is FALSE, it clears it (low).
1863
1864		eg: #define I2C_SDA(bit) \
1865			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1866			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
1867
1868		I2C_SCL(bit)
1869
1870		If <bit> is TRUE, sets the I2C clock line high. If it
1871		is FALSE, it clears it (low).
1872
1873		eg: #define I2C_SCL(bit) \
1874			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1875			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
1876
1877		I2C_DELAY
1878
1879		This delay is invoked four times per clock cycle so this
1880		controls the rate of data transfer.  The data rate thus
1881		is 1 / (I2C_DELAY * 4). Often defined to be something
1882		like:
1883
1884		#define I2C_DELAY  udelay(2)
1885
1886		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1887
1888		If your arch supports the generic GPIO framework (asm/gpio.h),
1889		then you may alternatively define the two GPIOs that are to be
1890		used as SCL / SDA.  Any of the previous I2C_xxx macros will
1891		have GPIO-based defaults assigned to them as appropriate.
1892
1893		You should define these to the GPIO value as given directly to
1894		the generic GPIO functions.
1895
1896		CONFIG_SYS_I2C_INIT_BOARD
1897
1898		When a board is reset during an i2c bus transfer
1899		chips might think that the current transfer is still
1900		in progress. On some boards it is possible to access
1901		the i2c SCLK line directly, either by using the
1902		processor pin as a GPIO or by having a second pin
1903		connected to the bus. If this option is defined a
1904		custom i2c_init_board() routine in boards/xxx/board.c
1905		is run early in the boot sequence.
1906
1907		CONFIG_SYS_I2C_BOARD_LATE_INIT
1908
1909		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
1910		defined a custom i2c_board_late_init() routine in
1911		boards/xxx/board.c is run AFTER the operations in i2c_init()
1912		is completed. This callpoint can be used to unreset i2c bus
1913		using CPU i2c controller register accesses for CPUs whose i2c
1914		controller provide such a method. It is called at the end of
1915		i2c_init() to allow i2c_init operations to setup the i2c bus
1916		controller on the CPU (e.g. setting bus speed & slave address).
1917
1918		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1919
1920		This option enables configuration of bi_iic_fast[] flags
1921		in u-boot bd_info structure based on u-boot environment
1922		variable "i2cfast". (see also i2cfast)
1923
1924		CONFIG_I2C_MULTI_BUS
1925
1926		This option allows the use of multiple I2C buses, each of which
1927		must have a controller.	 At any point in time, only one bus is
1928		active.	 To switch to a different bus, use the 'i2c dev' command.
1929		Note that bus numbering is zero-based.
1930
1931		CONFIG_SYS_I2C_NOPROBES
1932
1933		This option specifies a list of I2C devices that will be skipped
1934		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
1935		is set, specify a list of bus-device pairs.  Otherwise, specify
1936		a 1D array of device addresses
1937
1938		e.g.
1939			#undef	CONFIG_I2C_MULTI_BUS
1940			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1941
1942		will skip addresses 0x50 and 0x68 on a board with one I2C bus
1943
1944			#define CONFIG_I2C_MULTI_BUS
1945			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
1946
1947		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1948
1949		CONFIG_SYS_SPD_BUS_NUM
1950
1951		If defined, then this indicates the I2C bus number for DDR SPD.
1952		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1953
1954		CONFIG_SYS_RTC_BUS_NUM
1955
1956		If defined, then this indicates the I2C bus number for the RTC.
1957		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1958
1959		CONFIG_SYS_DTT_BUS_NUM
1960
1961		If defined, then this indicates the I2C bus number for the DTT.
1962		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
1963
1964		CONFIG_SYS_I2C_DTT_ADDR:
1965
1966		If defined, specifies the I2C address of the DTT device.
1967		If not defined, then U-Boot uses predefined value for
1968		specified DTT device.
1969
1970		CONFIG_FSL_I2C
1971
1972		Define this option if you want to use Freescale's I2C driver in
1973		drivers/i2c/fsl_i2c.c.
1974
1975		CONFIG_I2C_MUX
1976
1977		Define this option if you have I2C devices reached over 1 .. n
1978		I2C Muxes like the pca9544a. This option addes a new I2C
1979		Command "i2c bus [muxtype:muxaddr:muxchannel]" which adds a
1980		new I2C Bus to the existing I2C Busses. If you select the
1981		new Bus with "i2c dev", u-bbot sends first the commandos for
1982		the muxes to activate this new "bus".
1983
1984		CONFIG_I2C_MULTI_BUS must be also defined, to use this
1985		feature!
1986
1987		Example:
1988		Adding a new I2C Bus reached over 2 pca9544a muxes
1989			The First mux with address 70 and channel 6
1990			The Second mux with address 71 and channel 4
1991
1992		=> i2c bus pca9544a:70:6:pca9544a:71:4
1993
1994		Use the "i2c bus" command without parameter, to get a list
1995		of I2C Busses with muxes:
1996
1997		=> i2c bus
1998		Busses reached over muxes:
1999		Bus ID: 2
2000		  reached over Mux(es):
2001		    pca9544a@70 ch: 4
2002		Bus ID: 3
2003		  reached over Mux(es):
2004		    pca9544a@70 ch: 6
2005		    pca9544a@71 ch: 4
2006		=>
2007
2008		If you now switch to the new I2C Bus 3 with "i2c dev 3"
2009		u-boot first sends the command to the mux@70 to enable
2010		channel 6, and then the command to the mux@71 to enable
2011		the channel 4.
2012
2013		After that, you can use the "normal" i2c commands as
2014		usual to communicate with your I2C devices behind
2015		the 2 muxes.
2016
2017		This option is actually implemented for the bitbanging
2018		algorithm in common/soft_i2c.c and for the Hardware I2C
2019		Bus on the MPC8260. But it should be not so difficult
2020		to add this option to other architectures.
2021
2022		CONFIG_SOFT_I2C_READ_REPEATED_START
2023
2024		defining this will force the i2c_read() function in
2025		the soft_i2c driver to perform an I2C repeated start
2026		between writing the address pointer and reading the
2027		data.  If this define is omitted the default behaviour
2028		of doing a stop-start sequence will be used.  Most I2C
2029		devices can use either method, but some require one or
2030		the other.
2031
2032- SPI Support:	CONFIG_SPI
2033
2034		Enables SPI driver (so far only tested with
2035		SPI EEPROM, also an instance works with Crystal A/D and
2036		D/As on the SACSng board)
2037
2038		CONFIG_SH_SPI
2039
2040		Enables the driver for SPI controller on SuperH. Currently
2041		only SH7757 is supported.
2042
2043		CONFIG_SPI_X
2044
2045		Enables extended (16-bit) SPI EEPROM addressing.
2046		(symmetrical to CONFIG_I2C_X)
2047
2048		CONFIG_SOFT_SPI
2049
2050		Enables a software (bit-bang) SPI driver rather than
2051		using hardware support. This is a general purpose
2052		driver that only requires three general I/O port pins
2053		(two outputs, one input) to function. If this is
2054		defined, the board configuration must define several
2055		SPI configuration items (port pins to use, etc). For
2056		an example, see include/configs/sacsng.h.
2057
2058		CONFIG_HARD_SPI
2059
2060		Enables a hardware SPI driver for general-purpose reads
2061		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2062		must define a list of chip-select function pointers.
2063		Currently supported on some MPC8xxx processors.	 For an
2064		example, see include/configs/mpc8349emds.h.
2065
2066		CONFIG_MXC_SPI
2067
2068		Enables the driver for the SPI controllers on i.MX and MXC
2069		SoCs. Currently i.MX31/35/51 are supported.
2070
2071- FPGA Support: CONFIG_FPGA
2072
2073		Enables FPGA subsystem.
2074
2075		CONFIG_FPGA_<vendor>
2076
2077		Enables support for specific chip vendors.
2078		(ALTERA, XILINX)
2079
2080		CONFIG_FPGA_<family>
2081
2082		Enables support for FPGA family.
2083		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2084
2085		CONFIG_FPGA_COUNT
2086
2087		Specify the number of FPGA devices to support.
2088
2089		CONFIG_SYS_FPGA_PROG_FEEDBACK
2090
2091		Enable printing of hash marks during FPGA configuration.
2092
2093		CONFIG_SYS_FPGA_CHECK_BUSY
2094
2095		Enable checks on FPGA configuration interface busy
2096		status by the configuration function. This option
2097		will require a board or device specific function to
2098		be written.
2099
2100		CONFIG_FPGA_DELAY
2101
2102		If defined, a function that provides delays in the FPGA
2103		configuration driver.
2104
2105		CONFIG_SYS_FPGA_CHECK_CTRLC
2106		Allow Control-C to interrupt FPGA configuration
2107
2108		CONFIG_SYS_FPGA_CHECK_ERROR
2109
2110		Check for configuration errors during FPGA bitfile
2111		loading. For example, abort during Virtex II
2112		configuration if the INIT_B line goes low (which
2113		indicated a CRC error).
2114
2115		CONFIG_SYS_FPGA_WAIT_INIT
2116
2117		Maximum time to wait for the INIT_B line to deassert
2118		after PROB_B has been deasserted during a Virtex II
2119		FPGA configuration sequence. The default time is 500
2120		ms.
2121
2122		CONFIG_SYS_FPGA_WAIT_BUSY
2123
2124		Maximum time to wait for BUSY to deassert during
2125		Virtex II FPGA configuration. The default is 5 ms.
2126
2127		CONFIG_SYS_FPGA_WAIT_CONFIG
2128
2129		Time to wait after FPGA configuration. The default is
2130		200 ms.
2131
2132- Configuration Management:
2133		CONFIG_IDENT_STRING
2134
2135		If defined, this string will be added to the U-Boot
2136		version information (U_BOOT_VERSION)
2137
2138- Vendor Parameter Protection:
2139
2140		U-Boot considers the values of the environment
2141		variables "serial#" (Board Serial Number) and
2142		"ethaddr" (Ethernet Address) to be parameters that
2143		are set once by the board vendor / manufacturer, and
2144		protects these variables from casual modification by
2145		the user. Once set, these variables are read-only,
2146		and write or delete attempts are rejected. You can
2147		change this behaviour:
2148
2149		If CONFIG_ENV_OVERWRITE is #defined in your config
2150		file, the write protection for vendor parameters is
2151		completely disabled. Anybody can change or delete
2152		these parameters.
2153
2154		Alternatively, if you #define _both_ CONFIG_ETHADDR
2155		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2156		Ethernet address is installed in the environment,
2157		which can be changed exactly ONCE by the user. [The
2158		serial# is unaffected by this, i. e. it remains
2159		read-only.]
2160
2161- Protected RAM:
2162		CONFIG_PRAM
2163
2164		Define this variable to enable the reservation of
2165		"protected RAM", i. e. RAM which is not overwritten
2166		by U-Boot. Define CONFIG_PRAM to hold the number of
2167		kB you want to reserve for pRAM. You can overwrite
2168		this default value by defining an environment
2169		variable "pram" to the number of kB you want to
2170		reserve. Note that the board info structure will
2171		still show the full amount of RAM. If pRAM is
2172		reserved, a new environment variable "mem" will
2173		automatically be defined to hold the amount of
2174		remaining RAM in a form that can be passed as boot
2175		argument to Linux, for instance like that:
2176
2177			setenv bootargs ... mem=\${mem}
2178			saveenv
2179
2180		This way you can tell Linux not to use this memory,
2181		either, which results in a memory region that will
2182		not be affected by reboots.
2183
2184		*WARNING* If your board configuration uses automatic
2185		detection of the RAM size, you must make sure that
2186		this memory test is non-destructive. So far, the
2187		following board configurations are known to be
2188		"pRAM-clean":
2189
2190			IVMS8, IVML24, SPD8xx, TQM8xxL,
2191			HERMES, IP860, RPXlite, LWMON,
2192			FLAGADM, TQM8260
2193
2194- Error Recovery:
2195		CONFIG_PANIC_HANG
2196
2197		Define this variable to stop the system in case of a
2198		fatal error, so that you have to reset it manually.
2199		This is probably NOT a good idea for an embedded
2200		system where you want the system to reboot
2201		automatically as fast as possible, but it may be
2202		useful during development since you can try to debug
2203		the conditions that lead to the situation.
2204
2205		CONFIG_NET_RETRY_COUNT
2206
2207		This variable defines the number of retries for
2208		network operations like ARP, RARP, TFTP, or BOOTP
2209		before giving up the operation. If not defined, a
2210		default value of 5 is used.
2211
2212		CONFIG_ARP_TIMEOUT
2213
2214		Timeout waiting for an ARP reply in milliseconds.
2215
2216		CONFIG_NFS_TIMEOUT
2217
2218		Timeout in milliseconds used in NFS protocol.
2219		If you encounter "ERROR: Cannot umount" in nfs command,
2220		try longer timeout such as
2221		#define CONFIG_NFS_TIMEOUT 10000UL
2222
2223- Command Interpreter:
2224		CONFIG_AUTO_COMPLETE
2225
2226		Enable auto completion of commands using TAB.
2227
2228		Note that this feature has NOT been implemented yet
2229		for the "hush" shell.
2230
2231
2232		CONFIG_SYS_HUSH_PARSER
2233
2234		Define this variable to enable the "hush" shell (from
2235		Busybox) as command line interpreter, thus enabling
2236		powerful command line syntax like
2237		if...then...else...fi conditionals or `&&' and '||'
2238		constructs ("shell scripts").
2239
2240		If undefined, you get the old, much simpler behaviour
2241		with a somewhat smaller memory footprint.
2242
2243
2244		CONFIG_SYS_PROMPT_HUSH_PS2
2245
2246		This defines the secondary prompt string, which is
2247		printed when the command interpreter needs more input
2248		to complete a command. Usually "> ".
2249
2250	Note:
2251
2252		In the current implementation, the local variables
2253		space and global environment variables space are
2254		separated. Local variables are those you define by
2255		simply typing `name=value'. To access a local
2256		variable later on, you have write `$name' or
2257		`${name}'; to execute the contents of a variable
2258		directly type `$name' at the command prompt.
2259
2260		Global environment variables are those you use
2261		setenv/printenv to work with. To run a command stored
2262		in such a variable, you need to use the run command,
2263		and you must not use the '$' sign to access them.
2264
2265		To store commands and special characters in a
2266		variable, please use double quotation marks
2267		surrounding the whole text of the variable, instead
2268		of the backslashes before semicolons and special
2269		symbols.
2270
2271- Commandline Editing and History:
2272		CONFIG_CMDLINE_EDITING
2273
2274		Enable editing and History functions for interactive
2275		commandline input operations
2276
2277- Default Environment:
2278		CONFIG_EXTRA_ENV_SETTINGS
2279
2280		Define this to contain any number of null terminated
2281		strings (variable = value pairs) that will be part of
2282		the default environment compiled into the boot image.
2283
2284		For example, place something like this in your
2285		board's config file:
2286
2287		#define CONFIG_EXTRA_ENV_SETTINGS \
2288			"myvar1=value1\0" \
2289			"myvar2=value2\0"
2290
2291		Warning: This method is based on knowledge about the
2292		internal format how the environment is stored by the
2293		U-Boot code. This is NOT an official, exported
2294		interface! Although it is unlikely that this format
2295		will change soon, there is no guarantee either.
2296		You better know what you are doing here.
2297
2298		Note: overly (ab)use of the default environment is
2299		discouraged. Make sure to check other ways to preset
2300		the environment like the "source" command or the
2301		boot command first.
2302
2303		CONFIG_ENV_VARS_UBOOT_CONFIG
2304
2305		Define this in order to add variables describing the
2306		U-Boot build configuration to the default environment.
2307		These will be named arch, cpu, board, vendor, and soc.
2308
2309		Enabling this option will cause the following to be defined:
2310
2311		- CONFIG_SYS_ARCH
2312		- CONFIG_SYS_CPU
2313		- CONFIG_SYS_BOARD
2314		- CONFIG_SYS_VENDOR
2315		- CONFIG_SYS_SOC
2316
2317		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2318
2319		Define this in order to add variables describing certain
2320		run-time determined information about the hardware to the
2321		environment.  These will be named board_name, board_rev.
2322
2323- DataFlash Support:
2324		CONFIG_HAS_DATAFLASH
2325
2326		Defining this option enables DataFlash features and
2327		allows to read/write in Dataflash via the standard
2328		commands cp, md...
2329
2330- Serial Flash support
2331		CONFIG_CMD_SF
2332
2333		Defining this option enables SPI flash commands
2334		'sf probe/read/write/erase/update'.
2335
2336		Usage requires an initial 'probe' to define the serial
2337		flash parameters, followed by read/write/erase/update
2338		commands.
2339
2340		The following defaults may be provided by the platform
2341		to handle the common case when only a single serial
2342		flash is present on the system.
2343
2344		CONFIG_SF_DEFAULT_BUS		Bus identifier
2345		CONFIG_SF_DEFAULT_CS		Chip-select
2346		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2347		CONFIG_SF_DEFAULT_SPEED		in Hz
2348
2349- SystemACE Support:
2350		CONFIG_SYSTEMACE
2351
2352		Adding this option adds support for Xilinx SystemACE
2353		chips attached via some sort of local bus. The address
2354		of the chip must also be defined in the
2355		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2356
2357		#define CONFIG_SYSTEMACE
2358		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2359
2360		When SystemACE support is added, the "ace" device type
2361		becomes available to the fat commands, i.e. fatls.
2362
2363- TFTP Fixed UDP Port:
2364		CONFIG_TFTP_PORT
2365
2366		If this is defined, the environment variable tftpsrcp
2367		is used to supply the TFTP UDP source port value.
2368		If tftpsrcp isn't defined, the normal pseudo-random port
2369		number generator is used.
2370
2371		Also, the environment variable tftpdstp is used to supply
2372		the TFTP UDP destination port value.  If tftpdstp isn't
2373		defined, the normal port 69 is used.
2374
2375		The purpose for tftpsrcp is to allow a TFTP server to
2376		blindly start the TFTP transfer using the pre-configured
2377		target IP address and UDP port. This has the effect of
2378		"punching through" the (Windows XP) firewall, allowing
2379		the remainder of the TFTP transfer to proceed normally.
2380		A better solution is to properly configure the firewall,
2381		but sometimes that is not allowed.
2382
2383- Show boot progress:
2384		CONFIG_SHOW_BOOT_PROGRESS
2385
2386		Defining this option allows to add some board-
2387		specific code (calling a user-provided function
2388		"show_boot_progress(int)") that enables you to show
2389		the system's boot progress on some display (for
2390		example, some LED's) on your board. At the moment,
2391		the following checkpoints are implemented:
2392
2393- Detailed boot stage timing
2394		CONFIG_BOOTSTAGE
2395		Define this option to get detailed timing of each stage
2396		of the boot process.
2397
2398		CONFIG_BOOTSTAGE_USER_COUNT
2399		This is the number of available user bootstage records.
2400		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
2401		a new ID will be allocated from this stash. If you exceed
2402		the limit, recording will stop.
2403
2404		CONFIG_BOOTSTAGE_REPORT
2405		Define this to print a report before boot, similar to this:
2406
2407		Timer summary in microseconds:
2408		       Mark    Elapsed  Stage
2409			  0          0  reset
2410		  3,575,678  3,575,678  board_init_f start
2411		  3,575,695         17  arch_cpu_init A9
2412		  3,575,777         82  arch_cpu_init done
2413		  3,659,598     83,821  board_init_r start
2414		  3,910,375    250,777  main_loop
2415		 29,916,167 26,005,792  bootm_start
2416		 30,361,327    445,160  start_kernel
2417
2418		CONFIG_CMD_BOOTSTAGE
2419		Add a 'bootstage' command which supports printing a report
2420		and un/stashing of bootstage data.
2421
2422		CONFIG_BOOTSTAGE_FDT
2423		Stash the bootstage information in the FDT. A root 'bootstage'
2424		node is created with each bootstage id as a child. Each child
2425		has a 'name' property and either 'mark' containing the
2426		mark time in microsecond, or 'accum' containing the
2427		accumulated time for that bootstage id in microseconds.
2428		For example:
2429
2430		bootstage {
2431			154 {
2432				name = "board_init_f";
2433				mark = <3575678>;
2434			};
2435			170 {
2436				name = "lcd";
2437				accum = <33482>;
2438			};
2439		};
2440
2441		Code in the Linux kernel can find this in /proc/devicetree.
2442
2443Legacy uImage format:
2444
2445  Arg	Where			When
2446    1	common/cmd_bootm.c	before attempting to boot an image
2447   -1	common/cmd_bootm.c	Image header has bad	 magic number
2448    2	common/cmd_bootm.c	Image header has correct magic number
2449   -2	common/cmd_bootm.c	Image header has bad	 checksum
2450    3	common/cmd_bootm.c	Image header has correct checksum
2451   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2452    4	common/cmd_bootm.c	Image data   has correct checksum
2453   -4	common/cmd_bootm.c	Image is for unsupported architecture
2454    5	common/cmd_bootm.c	Architecture check OK
2455   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2456    6	common/cmd_bootm.c	Image Type check OK
2457   -6	common/cmd_bootm.c	gunzip uncompression error
2458   -7	common/cmd_bootm.c	Unimplemented compression type
2459    7	common/cmd_bootm.c	Uncompression OK
2460    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2461   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2462
2463    9	common/image.c		Start initial ramdisk verification
2464  -10	common/image.c		Ramdisk header has bad	   magic number
2465  -11	common/image.c		Ramdisk header has bad	   checksum
2466   10	common/image.c		Ramdisk header is OK
2467  -12	common/image.c		Ramdisk data   has bad	   checksum
2468   11	common/image.c		Ramdisk data   has correct checksum
2469   12	common/image.c		Ramdisk verification complete, start loading
2470  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2471   13	common/image.c		Start multifile image verification
2472   14	common/image.c		No initial ramdisk, no multifile, continue.
2473
2474   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2475
2476  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2477  -31	post/post.c		POST test failed, detected by post_output_backlog()
2478  -32	post/post.c		POST test failed, detected by post_run_single()
2479
2480   34	common/cmd_doc.c	before loading a Image from a DOC device
2481  -35	common/cmd_doc.c	Bad usage of "doc" command
2482   35	common/cmd_doc.c	correct usage of "doc" command
2483  -36	common/cmd_doc.c	No boot device
2484   36	common/cmd_doc.c	correct boot device
2485  -37	common/cmd_doc.c	Unknown Chip ID on boot device
2486   37	common/cmd_doc.c	correct chip ID found, device available
2487  -38	common/cmd_doc.c	Read Error on boot device
2488   38	common/cmd_doc.c	reading Image header from DOC device OK
2489  -39	common/cmd_doc.c	Image header has bad magic number
2490   39	common/cmd_doc.c	Image header has correct magic number
2491  -40	common/cmd_doc.c	Error reading Image from DOC device
2492   40	common/cmd_doc.c	Image header has correct magic number
2493   41	common/cmd_ide.c	before loading a Image from a IDE device
2494  -42	common/cmd_ide.c	Bad usage of "ide" command
2495   42	common/cmd_ide.c	correct usage of "ide" command
2496  -43	common/cmd_ide.c	No boot device
2497   43	common/cmd_ide.c	boot device found
2498  -44	common/cmd_ide.c	Device not available
2499   44	common/cmd_ide.c	Device available
2500  -45	common/cmd_ide.c	wrong partition selected
2501   45	common/cmd_ide.c	partition selected
2502  -46	common/cmd_ide.c	Unknown partition table
2503   46	common/cmd_ide.c	valid partition table found
2504  -47	common/cmd_ide.c	Invalid partition type
2505   47	common/cmd_ide.c	correct partition type
2506  -48	common/cmd_ide.c	Error reading Image Header on boot device
2507   48	common/cmd_ide.c	reading Image Header from IDE device OK
2508  -49	common/cmd_ide.c	Image header has bad magic number
2509   49	common/cmd_ide.c	Image header has correct magic number
2510  -50	common/cmd_ide.c	Image header has bad	 checksum
2511   50	common/cmd_ide.c	Image header has correct checksum
2512  -51	common/cmd_ide.c	Error reading Image from IDE device
2513   51	common/cmd_ide.c	reading Image from IDE device OK
2514   52	common/cmd_nand.c	before loading a Image from a NAND device
2515  -53	common/cmd_nand.c	Bad usage of "nand" command
2516   53	common/cmd_nand.c	correct usage of "nand" command
2517  -54	common/cmd_nand.c	No boot device
2518   54	common/cmd_nand.c	boot device found
2519  -55	common/cmd_nand.c	Unknown Chip ID on boot device
2520   55	common/cmd_nand.c	correct chip ID found, device available
2521  -56	common/cmd_nand.c	Error reading Image Header on boot device
2522   56	common/cmd_nand.c	reading Image Header from NAND device OK
2523  -57	common/cmd_nand.c	Image header has bad magic number
2524   57	common/cmd_nand.c	Image header has correct magic number
2525  -58	common/cmd_nand.c	Error reading Image from NAND device
2526   58	common/cmd_nand.c	reading Image from NAND device OK
2527
2528  -60	common/env_common.c	Environment has a bad CRC, using default
2529
2530   64	net/eth.c		starting with Ethernet configuration.
2531  -64	net/eth.c		no Ethernet found.
2532   65	net/eth.c		Ethernet found.
2533
2534  -80	common/cmd_net.c	usage wrong
2535   80	common/cmd_net.c	before calling NetLoop()
2536  -81	common/cmd_net.c	some error in NetLoop() occurred
2537   81	common/cmd_net.c	NetLoop() back without error
2538  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
2539   82	common/cmd_net.c	trying automatic boot
2540   83	common/cmd_net.c	running "source" command
2541  -83	common/cmd_net.c	some error in automatic boot or "source" command
2542   84	common/cmd_net.c	end without errors
2543
2544FIT uImage format:
2545
2546  Arg	Where			When
2547  100	common/cmd_bootm.c	Kernel FIT Image has correct format
2548 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
2549  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
2550 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
2551  102	common/cmd_bootm.c	Kernel unit name specified
2552 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
2553  103	common/cmd_bootm.c	Found configuration node
2554  104	common/cmd_bootm.c	Got kernel subimage node offset
2555 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
2556  105	common/cmd_bootm.c	Kernel subimage hash verification OK
2557 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
2558  106	common/cmd_bootm.c	Architecture check OK
2559 -106	common/cmd_bootm.c	Kernel subimage has wrong type
2560  107	common/cmd_bootm.c	Kernel subimage type OK
2561 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
2562  108	common/cmd_bootm.c	Got kernel subimage data/size
2563 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
2564 -109	common/cmd_bootm.c	Can't get kernel subimage type
2565 -110	common/cmd_bootm.c	Can't get kernel subimage comp
2566 -111	common/cmd_bootm.c	Can't get kernel subimage os
2567 -112	common/cmd_bootm.c	Can't get kernel subimage load address
2568 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
2569
2570  120	common/image.c		Start initial ramdisk verification
2571 -120	common/image.c		Ramdisk FIT image has incorrect format
2572  121	common/image.c		Ramdisk FIT image has correct format
2573  122	common/image.c		No ramdisk subimage unit name, using configuration
2574 -122	common/image.c		Can't get configuration for ramdisk subimage
2575  123	common/image.c		Ramdisk unit name specified
2576 -124	common/image.c		Can't get ramdisk subimage node offset
2577  125	common/image.c		Got ramdisk subimage node offset
2578 -125	common/image.c		Ramdisk subimage hash verification failed
2579  126	common/image.c		Ramdisk subimage hash verification OK
2580 -126	common/image.c		Ramdisk subimage for unsupported architecture
2581  127	common/image.c		Architecture check OK
2582 -127	common/image.c		Can't get ramdisk subimage data/size
2583  128	common/image.c		Got ramdisk subimage data/size
2584  129	common/image.c		Can't get ramdisk load address
2585 -129	common/image.c		Got ramdisk load address
2586
2587 -130	common/cmd_doc.c	Incorrect FIT image format
2588  131	common/cmd_doc.c	FIT image format OK
2589
2590 -140	common/cmd_ide.c	Incorrect FIT image format
2591  141	common/cmd_ide.c	FIT image format OK
2592
2593 -150	common/cmd_nand.c	Incorrect FIT image format
2594  151	common/cmd_nand.c	FIT image format OK
2595
2596- Standalone program support:
2597		CONFIG_STANDALONE_LOAD_ADDR
2598
2599		This option defines a board specific value for the
2600		address where standalone program gets loaded, thus
2601		overwriting the architecture dependent default
2602		settings.
2603
2604- Frame Buffer Address:
2605		CONFIG_FB_ADDR
2606
2607		Define CONFIG_FB_ADDR if you want to use specific
2608		address for frame buffer.
2609		Then system will reserve the frame buffer address to
2610		defined address instead of lcd_setmem (this function
2611		grabs the memory for frame buffer by panel's size).
2612
2613		Please see board_init_f function.
2614
2615- Automatic software updates via TFTP server
2616		CONFIG_UPDATE_TFTP
2617		CONFIG_UPDATE_TFTP_CNT_MAX
2618		CONFIG_UPDATE_TFTP_MSEC_MAX
2619
2620		These options enable and control the auto-update feature;
2621		for a more detailed description refer to doc/README.update.
2622
2623- MTD Support (mtdparts command, UBI support)
2624		CONFIG_MTD_DEVICE
2625
2626		Adds the MTD device infrastructure from the Linux kernel.
2627		Needed for mtdparts command support.
2628
2629		CONFIG_MTD_PARTITIONS
2630
2631		Adds the MTD partitioning infrastructure from the Linux
2632		kernel. Needed for UBI support.
2633
2634- SPL framework
2635		CONFIG_SPL
2636		Enable building of SPL globally.
2637
2638		CONFIG_SPL_LDSCRIPT
2639		LDSCRIPT for linking the SPL binary.
2640
2641		CONFIG_SPL_MAX_SIZE
2642		Maximum binary size (text, data and rodata) of the SPL binary.
2643
2644		CONFIG_SPL_TEXT_BASE
2645		TEXT_BASE for linking the SPL binary.
2646
2647		CONFIG_SPL_BSS_START_ADDR
2648		Link address for the BSS within the SPL binary.
2649
2650		CONFIG_SPL_BSS_MAX_SIZE
2651		Maximum binary size of the BSS section of the SPL binary.
2652
2653		CONFIG_SPL_STACK
2654		Adress of the start of the stack SPL will use
2655
2656		CONFIG_SYS_SPL_MALLOC_START
2657		Starting address of the malloc pool used in SPL.
2658
2659		CONFIG_SYS_SPL_MALLOC_SIZE
2660		The size of the malloc pool used in SPL.
2661
2662		CONFIG_SPL_FRAMEWORK
2663		Enable the SPL framework under common/.  This framework
2664		supports MMC, NAND and YMODEM loading of U-Boot and NAND
2665		NAND loading of the Linux Kernel.
2666
2667		CONFIG_SPL_DISPLAY_PRINT
2668		For ARM, enable an optional function to print more information
2669		about the running system.
2670
2671		CONFIG_SPL_LIBCOMMON_SUPPORT
2672		Support for common/libcommon.o in SPL binary
2673
2674		CONFIG_SPL_LIBDISK_SUPPORT
2675		Support for disk/libdisk.o in SPL binary
2676
2677		CONFIG_SPL_I2C_SUPPORT
2678		Support for drivers/i2c/libi2c.o in SPL binary
2679
2680		CONFIG_SPL_GPIO_SUPPORT
2681		Support for drivers/gpio/libgpio.o in SPL binary
2682
2683		CONFIG_SPL_MMC_SUPPORT
2684		Support for drivers/mmc/libmmc.o in SPL binary
2685
2686		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
2687		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
2688		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
2689		Address, size and partition on the MMC to load U-Boot from
2690		when the MMC is being used in raw mode.
2691
2692		CONFIG_SPL_FAT_SUPPORT
2693		Support for fs/fat/libfat.o in SPL binary
2694
2695		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
2696		Filename to read to load U-Boot when reading from FAT
2697
2698		CONFIG_SPL_NAND_SIMPLE
2699		Support for drivers/mtd/nand/libnand.o in SPL binary
2700
2701		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
2702		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
2703		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
2704		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
2705		CONFIG_SYS_NAND_ECCBYTES
2706		Defines the size and behavior of the NAND that SPL uses
2707		to read U-Boot with CONFIG_SPL_NAND_SIMPLE
2708
2709		CONFIG_SYS_NAND_U_BOOT_OFFS
2710		Location in NAND for CONFIG_SPL_NAND_SIMPLE to read U-Boot
2711		from.
2712
2713		CONFIG_SYS_NAND_U_BOOT_START
2714		Location in memory for CONFIG_SPL_NAND_SIMPLE to load U-Boot
2715		to.
2716
2717		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
2718		Define this if you need to first read the OOB and then the
2719		data. This is used for example on davinci plattforms.
2720
2721		CONFIG_SPL_OMAP3_ID_NAND
2722		Support for an OMAP3-specific set of functions to return the
2723		ID and MFR of the first attached NAND chip, if present.
2724
2725		CONFIG_SPL_SERIAL_SUPPORT
2726		Support for drivers/serial/libserial.o in SPL binary
2727
2728		CONFIG_SPL_SPI_FLASH_SUPPORT
2729		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
2730
2731		CONFIG_SPL_SPI_SUPPORT
2732		Support for drivers/spi/libspi.o in SPL binary
2733
2734		CONFIG_SPL_RAM_DEVICE
2735		Support for running image already present in ram, in SPL binary
2736
2737		CONFIG_SPL_LIBGENERIC_SUPPORT
2738		Support for lib/libgeneric.o in SPL binary
2739
2740Modem Support:
2741--------------
2742
2743[so far only for SMDK2400 boards]
2744
2745- Modem support enable:
2746		CONFIG_MODEM_SUPPORT
2747
2748- RTS/CTS Flow control enable:
2749		CONFIG_HWFLOW
2750
2751- Modem debug support:
2752		CONFIG_MODEM_SUPPORT_DEBUG
2753
2754		Enables debugging stuff (char screen[1024], dbg())
2755		for modem support. Useful only with BDI2000.
2756
2757- Interrupt support (PPC):
2758
2759		There are common interrupt_init() and timer_interrupt()
2760		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2761		for CPU specific initialization. interrupt_init_cpu()
2762		should set decrementer_count to appropriate value. If
2763		CPU resets decrementer automatically after interrupt
2764		(ppc4xx) it should set decrementer_count to zero.
2765		timer_interrupt() calls timer_interrupt_cpu() for CPU
2766		specific handling. If board has watchdog / status_led
2767		/ other_activity_monitor it works automatically from
2768		general timer_interrupt().
2769
2770- General:
2771
2772		In the target system modem support is enabled when a
2773		specific key (key combination) is pressed during
2774		power-on. Otherwise U-Boot will boot normally
2775		(autoboot). The key_pressed() function is called from
2776		board_init(). Currently key_pressed() is a dummy
2777		function, returning 1 and thus enabling modem
2778		initialization.
2779
2780		If there are no modem init strings in the
2781		environment, U-Boot proceed to autoboot; the
2782		previous output (banner, info printfs) will be
2783		suppressed, though.
2784
2785		See also: doc/README.Modem
2786
2787Board initialization settings:
2788------------------------------
2789
2790During Initialization u-boot calls a number of board specific functions
2791to allow the preparation of board specific prerequisites, e.g. pin setup
2792before drivers are initialized. To enable these callbacks the
2793following configuration macros have to be defined. Currently this is
2794architecture specific, so please check arch/your_architecture/lib/board.c
2795typically in board_init_f() and board_init_r().
2796
2797- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2798- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2799- CONFIG_BOARD_LATE_INIT: Call board_late_init()
2800- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2801
2802Configuration Settings:
2803-----------------------
2804
2805- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2806		undefine this when you're short of memory.
2807
2808- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2809		width of the commands listed in the 'help' command output.
2810
2811- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
2812		prompt for user input.
2813
2814- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
2815
2816- CONFIG_SYS_PBSIZE:	Buffer size for Console output
2817
2818- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
2819
2820- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2821		the application (usually a Linux kernel) when it is
2822		booted
2823
2824- CONFIG_SYS_BAUDRATE_TABLE:
2825		List of legal baudrate settings for this board.
2826
2827- CONFIG_SYS_CONSOLE_INFO_QUIET
2828		Suppress display of console information at boot.
2829
2830- CONFIG_SYS_CONSOLE_IS_IN_ENV
2831		If the board specific function
2832			extern int overwrite_console (void);
2833		returns 1, the stdin, stderr and stdout are switched to the
2834		serial port, else the settings in the environment are used.
2835
2836- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
2837		Enable the call to overwrite_console().
2838
2839- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
2840		Enable overwrite of previous console environment settings.
2841
2842- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
2843		Begin and End addresses of the area used by the
2844		simple memory test.
2845
2846- CONFIG_SYS_ALT_MEMTEST:
2847		Enable an alternate, more extensive memory test.
2848
2849- CONFIG_SYS_MEMTEST_SCRATCH:
2850		Scratch address used by the alternate memory test
2851		You only need to set this if address zero isn't writeable
2852
2853- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
2854		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2855		this specified memory area will get subtracted from the top
2856		(end) of RAM and won't get "touched" at all by U-Boot. By
2857		fixing up gd->ram_size the Linux kernel should gets passed
2858		the now "corrected" memory size and won't touch it either.
2859		This should work for arch/ppc and arch/powerpc. Only Linux
2860		board ports in arch/powerpc with bootwrapper support that
2861		recalculate the memory size from the SDRAM controller setup
2862		will have to get fixed in Linux additionally.
2863
2864		This option can be used as a workaround for the 440EPx/GRx
2865		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2866		be touched.
2867
2868		WARNING: Please make sure that this value is a multiple of
2869		the Linux page size (normally 4k). If this is not the case,
2870		then the end address of the Linux memory will be located at a
2871		non page size aligned address and this could cause major
2872		problems.
2873
2874- CONFIG_SYS_TFTP_LOADADDR:
2875		Default load address for network file downloads
2876
2877- CONFIG_SYS_LOADS_BAUD_CHANGE:
2878		Enable temporary baudrate change while serial download
2879
2880- CONFIG_SYS_SDRAM_BASE:
2881		Physical start address of SDRAM. _Must_ be 0 here.
2882
2883- CONFIG_SYS_MBIO_BASE:
2884		Physical start address of Motherboard I/O (if using a
2885		Cogent motherboard)
2886
2887- CONFIG_SYS_FLASH_BASE:
2888		Physical start address of Flash memory.
2889
2890- CONFIG_SYS_MONITOR_BASE:
2891		Physical start address of boot monitor code (set by
2892		make config files to be same as the text base address
2893		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
2894		CONFIG_SYS_FLASH_BASE when booting from flash.
2895
2896- CONFIG_SYS_MONITOR_LEN:
2897		Size of memory reserved for monitor code, used to
2898		determine _at_compile_time_ (!) if the environment is
2899		embedded within the U-Boot image, or in a separate
2900		flash sector.
2901
2902- CONFIG_SYS_MALLOC_LEN:
2903		Size of DRAM reserved for malloc() use.
2904
2905- CONFIG_SYS_BOOTM_LEN:
2906		Normally compressed uImages are limited to an
2907		uncompressed size of 8 MBytes. If this is not enough,
2908		you can define CONFIG_SYS_BOOTM_LEN in your board config file
2909		to adjust this setting to your needs.
2910
2911- CONFIG_SYS_BOOTMAPSZ:
2912		Maximum size of memory mapped by the startup code of
2913		the Linux kernel; all data that must be processed by
2914		the Linux kernel (bd_info, boot arguments, FDT blob if
2915		used) must be put below this limit, unless "bootm_low"
2916		enviroment variable is defined and non-zero. In such case
2917		all data for the Linux kernel must be between "bootm_low"
2918		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
2919		variable "bootm_mapsize" will override the value of
2920		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
2921		then the value in "bootm_size" will be used instead.
2922
2923- CONFIG_SYS_BOOT_RAMDISK_HIGH:
2924		Enable initrd_high functionality.  If defined then the
2925		initrd_high feature is enabled and the bootm ramdisk subcommand
2926		is enabled.
2927
2928- CONFIG_SYS_BOOT_GET_CMDLINE:
2929		Enables allocating and saving kernel cmdline in space between
2930		"bootm_low" and "bootm_low" + BOOTMAPSZ.
2931
2932- CONFIG_SYS_BOOT_GET_KBD:
2933		Enables allocating and saving a kernel copy of the bd_info in
2934		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2935
2936- CONFIG_SYS_MAX_FLASH_BANKS:
2937		Max number of Flash memory banks
2938
2939- CONFIG_SYS_MAX_FLASH_SECT:
2940		Max number of sectors on a Flash chip
2941
2942- CONFIG_SYS_FLASH_ERASE_TOUT:
2943		Timeout for Flash erase operations (in ms)
2944
2945- CONFIG_SYS_FLASH_WRITE_TOUT:
2946		Timeout for Flash write operations (in ms)
2947
2948- CONFIG_SYS_FLASH_LOCK_TOUT
2949		Timeout for Flash set sector lock bit operation (in ms)
2950
2951- CONFIG_SYS_FLASH_UNLOCK_TOUT
2952		Timeout for Flash clear lock bits operation (in ms)
2953
2954- CONFIG_SYS_FLASH_PROTECTION
2955		If defined, hardware flash sectors protection is used
2956		instead of U-Boot software protection.
2957
2958- CONFIG_SYS_DIRECT_FLASH_TFTP:
2959
2960		Enable TFTP transfers directly to flash memory;
2961		without this option such a download has to be
2962		performed in two steps: (1) download to RAM, and (2)
2963		copy from RAM to flash.
2964
2965		The two-step approach is usually more reliable, since
2966		you can check if the download worked before you erase
2967		the flash, but in some situations (when system RAM is
2968		too limited to allow for a temporary copy of the
2969		downloaded image) this option may be very useful.
2970
2971- CONFIG_SYS_FLASH_CFI:
2972		Define if the flash driver uses extra elements in the
2973		common flash structure for storing flash geometry.
2974
2975- CONFIG_FLASH_CFI_DRIVER
2976		This option also enables the building of the cfi_flash driver
2977		in the drivers directory
2978
2979- CONFIG_FLASH_CFI_MTD
2980		This option enables the building of the cfi_mtd driver
2981		in the drivers directory. The driver exports CFI flash
2982		to the MTD layer.
2983
2984- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2985		Use buffered writes to flash.
2986
2987- CONFIG_FLASH_SPANSION_S29WS_N
2988		s29ws-n MirrorBit flash has non-standard addresses for buffered
2989		write commands.
2990
2991- CONFIG_SYS_FLASH_QUIET_TEST
2992		If this option is defined, the common CFI flash doesn't
2993		print it's warning upon not recognized FLASH banks. This
2994		is useful, if some of the configured banks are only
2995		optionally available.
2996
2997- CONFIG_FLASH_SHOW_PROGRESS
2998		If defined (must be an integer), print out countdown
2999		digits and dots.  Recommended value: 45 (9..1) for 80
3000		column displays, 15 (3..1) for 40 column displays.
3001
3002- CONFIG_SYS_RX_ETH_BUFFER:
3003		Defines the number of Ethernet receive buffers. On some
3004		Ethernet controllers it is recommended to set this value
3005		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3006		buffers can be full shortly after enabling the interface
3007		on high Ethernet traffic.
3008		Defaults to 4 if not defined.
3009
3010- CONFIG_ENV_MAX_ENTRIES
3011
3012	Maximum number of entries in the hash table that is used
3013	internally to store the environment settings. The default
3014	setting is supposed to be generous and should work in most
3015	cases. This setting can be used to tune behaviour; see
3016	lib/hashtable.c for details.
3017
3018The following definitions that deal with the placement and management
3019of environment data (variable area); in general, we support the
3020following configurations:
3021
3022- CONFIG_BUILD_ENVCRC:
3023
3024	Builds up envcrc with the target environment so that external utils
3025	may easily extract it and embed it in final U-Boot images.
3026
3027- CONFIG_ENV_IS_IN_FLASH:
3028
3029	Define this if the environment is in flash memory.
3030
3031	a) The environment occupies one whole flash sector, which is
3032	   "embedded" in the text segment with the U-Boot code. This
3033	   happens usually with "bottom boot sector" or "top boot
3034	   sector" type flash chips, which have several smaller
3035	   sectors at the start or the end. For instance, such a
3036	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3037	   such a case you would place the environment in one of the
3038	   4 kB sectors - with U-Boot code before and after it. With
3039	   "top boot sector" type flash chips, you would put the
3040	   environment in one of the last sectors, leaving a gap
3041	   between U-Boot and the environment.
3042
3043	- CONFIG_ENV_OFFSET:
3044
3045	   Offset of environment data (variable area) to the
3046	   beginning of flash memory; for instance, with bottom boot
3047	   type flash chips the second sector can be used: the offset
3048	   for this sector is given here.
3049
3050	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3051
3052	- CONFIG_ENV_ADDR:
3053
3054	   This is just another way to specify the start address of
3055	   the flash sector containing the environment (instead of
3056	   CONFIG_ENV_OFFSET).
3057
3058	- CONFIG_ENV_SECT_SIZE:
3059
3060	   Size of the sector containing the environment.
3061
3062
3063	b) Sometimes flash chips have few, equal sized, BIG sectors.
3064	   In such a case you don't want to spend a whole sector for
3065	   the environment.
3066
3067	- CONFIG_ENV_SIZE:
3068
3069	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3070	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3071	   of this flash sector for the environment. This saves
3072	   memory for the RAM copy of the environment.
3073
3074	   It may also save flash memory if you decide to use this
3075	   when your environment is "embedded" within U-Boot code,
3076	   since then the remainder of the flash sector could be used
3077	   for U-Boot code. It should be pointed out that this is
3078	   STRONGLY DISCOURAGED from a robustness point of view:
3079	   updating the environment in flash makes it always
3080	   necessary to erase the WHOLE sector. If something goes
3081	   wrong before the contents has been restored from a copy in
3082	   RAM, your target system will be dead.
3083
3084	- CONFIG_ENV_ADDR_REDUND
3085	  CONFIG_ENV_SIZE_REDUND
3086
3087	   These settings describe a second storage area used to hold
3088	   a redundant copy of the environment data, so that there is
3089	   a valid backup copy in case there is a power failure during
3090	   a "saveenv" operation.
3091
3092BE CAREFUL! Any changes to the flash layout, and some changes to the
3093source code will make it necessary to adapt <board>/u-boot.lds*
3094accordingly!
3095
3096
3097- CONFIG_ENV_IS_IN_NVRAM:
3098
3099	Define this if you have some non-volatile memory device
3100	(NVRAM, battery buffered SRAM) which you want to use for the
3101	environment.
3102
3103	- CONFIG_ENV_ADDR:
3104	- CONFIG_ENV_SIZE:
3105
3106	  These two #defines are used to determine the memory area you
3107	  want to use for environment. It is assumed that this memory
3108	  can just be read and written to, without any special
3109	  provision.
3110
3111BE CAREFUL! The first access to the environment happens quite early
3112in U-Boot initalization (when we try to get the setting of for the
3113console baudrate). You *MUST* have mapped your NVRAM area then, or
3114U-Boot will hang.
3115
3116Please note that even with NVRAM we still use a copy of the
3117environment in RAM: we could work on NVRAM directly, but we want to
3118keep settings there always unmodified except somebody uses "saveenv"
3119to save the current settings.
3120
3121
3122- CONFIG_ENV_IS_IN_EEPROM:
3123
3124	Use this if you have an EEPROM or similar serial access
3125	device and a driver for it.
3126
3127	- CONFIG_ENV_OFFSET:
3128	- CONFIG_ENV_SIZE:
3129
3130	  These two #defines specify the offset and size of the
3131	  environment area within the total memory of your EEPROM.
3132
3133	- CONFIG_SYS_I2C_EEPROM_ADDR:
3134	  If defined, specified the chip address of the EEPROM device.
3135	  The default address is zero.
3136
3137	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3138	  If defined, the number of bits used to address bytes in a
3139	  single page in the EEPROM device.  A 64 byte page, for example
3140	  would require six bits.
3141
3142	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3143	  If defined, the number of milliseconds to delay between
3144	  page writes.	The default is zero milliseconds.
3145
3146	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3147	  The length in bytes of the EEPROM memory array address.  Note
3148	  that this is NOT the chip address length!
3149
3150	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3151	  EEPROM chips that implement "address overflow" are ones
3152	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3153	  address and the extra bits end up in the "chip address" bit
3154	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3155	  byte chips.
3156
3157	  Note that we consider the length of the address field to
3158	  still be one byte because the extra address bits are hidden
3159	  in the chip address.
3160
3161	- CONFIG_SYS_EEPROM_SIZE:
3162	  The size in bytes of the EEPROM device.
3163
3164	- CONFIG_ENV_EEPROM_IS_ON_I2C
3165	  define this, if you have I2C and SPI activated, and your
3166	  EEPROM, which holds the environment, is on the I2C bus.
3167
3168	- CONFIG_I2C_ENV_EEPROM_BUS
3169	  if you have an Environment on an EEPROM reached over
3170	  I2C muxes, you can define here, how to reach this
3171	  EEPROM. For example:
3172
3173	  #define CONFIG_I2C_ENV_EEPROM_BUS	  "pca9547:70:d\0"
3174
3175	  EEPROM which holds the environment, is reached over
3176	  a pca9547 i2c mux with address 0x70, channel 3.
3177
3178- CONFIG_ENV_IS_IN_DATAFLASH:
3179
3180	Define this if you have a DataFlash memory device which you
3181	want to use for the environment.
3182
3183	- CONFIG_ENV_OFFSET:
3184	- CONFIG_ENV_ADDR:
3185	- CONFIG_ENV_SIZE:
3186
3187	  These three #defines specify the offset and size of the
3188	  environment area within the total memory of your DataFlash placed
3189	  at the specified address.
3190
3191- CONFIG_ENV_IS_IN_REMOTE:
3192
3193	Define this if you have a remote memory space which you
3194	want to use for the local device's environment.
3195
3196	- CONFIG_ENV_ADDR:
3197	- CONFIG_ENV_SIZE:
3198
3199	  These two #defines specify the address and size of the
3200	  environment area within the remote memory space. The
3201	  local device can get the environment from remote memory
3202	  space by SRIO or PCIE links.
3203
3204BE CAREFUL! For some special cases, the local device can not use
3205"saveenv" command. For example, the local device will get the
3206environment stored in a remote NOR flash by SRIO or PCIE link,
3207but it can not erase, write this NOR flash by SRIO or PCIE interface.
3208
3209- CONFIG_ENV_IS_IN_NAND:
3210
3211	Define this if you have a NAND device which you want to use
3212	for the environment.
3213
3214	- CONFIG_ENV_OFFSET:
3215	- CONFIG_ENV_SIZE:
3216
3217	  These two #defines specify the offset and size of the environment
3218	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
3219	  aligned to an erase block boundary.
3220
3221	- CONFIG_ENV_OFFSET_REDUND (optional):
3222
3223	  This setting describes a second storage area of CONFIG_ENV_SIZE
3224	  size used to hold a redundant copy of the environment data, so
3225	  that there is a valid backup copy in case there is a power failure
3226	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
3227	  aligned to an erase block boundary.
3228
3229	- CONFIG_ENV_RANGE (optional):
3230
3231	  Specifies the length of the region in which the environment
3232	  can be written.  This should be a multiple of the NAND device's
3233	  block size.  Specifying a range with more erase blocks than
3234	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
3235	  the range to be avoided.
3236
3237	- CONFIG_ENV_OFFSET_OOB (optional):
3238
3239	  Enables support for dynamically retrieving the offset of the
3240	  environment from block zero's out-of-band data.  The
3241	  "nand env.oob" command can be used to record this offset.
3242	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
3243	  using CONFIG_ENV_OFFSET_OOB.
3244
3245- CONFIG_NAND_ENV_DST
3246
3247	Defines address in RAM to which the nand_spl code should copy the
3248	environment. If redundant environment is used, it will be copied to
3249	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3250
3251- CONFIG_SYS_SPI_INIT_OFFSET
3252
3253	Defines offset to the initial SPI buffer area in DPRAM. The
3254	area is used at an early stage (ROM part) if the environment
3255	is configured to reside in the SPI EEPROM: We need a 520 byte
3256	scratch DPRAM area. It is used between the two initialization
3257	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
3258	to be a good choice since it makes it far enough from the
3259	start of the data area as well as from the stack pointer.
3260
3261Please note that the environment is read-only until the monitor
3262has been relocated to RAM and a RAM copy of the environment has been
3263created; also, when using EEPROM you will have to use getenv_f()
3264until then to read environment variables.
3265
3266The environment is protected by a CRC32 checksum. Before the monitor
3267is relocated into RAM, as a result of a bad CRC you will be working
3268with the compiled-in default environment - *silently*!!! [This is
3269necessary, because the first environment variable we need is the
3270"baudrate" setting for the console - if we have a bad CRC, we don't
3271have any device yet where we could complain.]
3272
3273Note: once the monitor has been relocated, then it will complain if
3274the default environment is used; a new CRC is computed as soon as you
3275use the "saveenv" command to store a valid environment.
3276
3277- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
3278		Echo the inverted Ethernet link state to the fault LED.
3279
3280		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
3281		      also needs to be defined.
3282
3283- CONFIG_SYS_FAULT_MII_ADDR:
3284		MII address of the PHY to check for the Ethernet link state.
3285
3286- CONFIG_NS16550_MIN_FUNCTIONS:
3287		Define this if you desire to only have use of the NS16550_init
3288		and NS16550_putc functions for the serial driver located at
3289		drivers/serial/ns16550.c.  This option is useful for saving
3290		space for already greatly restricted images, including but not
3291		limited to NAND_SPL configurations.
3292
3293Low Level (hardware related) configuration options:
3294---------------------------------------------------
3295
3296- CONFIG_SYS_CACHELINE_SIZE:
3297		Cache Line Size of the CPU.
3298
3299- CONFIG_SYS_DEFAULT_IMMR:
3300		Default address of the IMMR after system reset.
3301
3302		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
3303		and RPXsuper) to be able to adjust the position of
3304		the IMMR register after a reset.
3305
3306- CONFIG_SYS_CCSRBAR_DEFAULT:
3307		Default (power-on reset) physical address of CCSR on Freescale
3308		PowerPC SOCs.
3309
3310- CONFIG_SYS_CCSRBAR:
3311		Virtual address of CCSR.  On a 32-bit build, this is typically
3312		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
3313
3314		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
3315		for cross-platform code that uses that macro instead.
3316
3317- CONFIG_SYS_CCSRBAR_PHYS:
3318		Physical address of CCSR.  CCSR can be relocated to a new
3319		physical address, if desired.  In this case, this macro should
3320		be set to that address.	 Otherwise, it should be set to the
3321		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
3322		is typically relocated on 36-bit builds.  It is recommended
3323		that this macro be defined via the _HIGH and _LOW macros:
3324
3325		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
3326			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
3327
3328- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
3329		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
3330		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
3331		used in assembly code, so it must not contain typecasts or
3332		integer size suffixes (e.g. "ULL").
3333
3334- CONFIG_SYS_CCSRBAR_PHYS_LOW:
3335		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
3336		used in assembly code, so it must not contain typecasts or
3337		integer size suffixes (e.g. "ULL").
3338
3339- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
3340		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
3341		forced to a value that ensures that CCSR is not relocated.
3342
3343- Floppy Disk Support:
3344		CONFIG_SYS_FDC_DRIVE_NUMBER
3345
3346		the default drive number (default value 0)
3347
3348		CONFIG_SYS_ISA_IO_STRIDE
3349
3350		defines the spacing between FDC chipset registers
3351		(default value 1)
3352
3353		CONFIG_SYS_ISA_IO_OFFSET
3354
3355		defines the offset of register from address. It
3356		depends on which part of the data bus is connected to
3357		the FDC chipset. (default value 0)
3358
3359		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
3360		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
3361		default value.
3362
3363		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
3364		fdc_hw_init() is called at the beginning of the FDC
3365		setup. fdc_hw_init() must be provided by the board
3366		source code. It is used to make hardware dependant
3367		initializations.
3368
3369- CONFIG_IDE_AHB:
3370		Most IDE controllers were designed to be connected with PCI
3371		interface. Only few of them were designed for AHB interface.
3372		When software is doing ATA command and data transfer to
3373		IDE devices through IDE-AHB controller, some additional
3374		registers accessing to these kind of IDE-AHB controller
3375		is requierd.
3376
3377- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
3378		DO NOT CHANGE unless you know exactly what you're
3379		doing! (11-4) [MPC8xx/82xx systems only]
3380
3381- CONFIG_SYS_INIT_RAM_ADDR:
3382
3383		Start address of memory area that can be used for
3384		initial data and stack; please note that this must be
3385		writable memory that is working WITHOUT special
3386		initialization, i. e. you CANNOT use normal RAM which
3387		will become available only after programming the
3388		memory controller and running certain initialization
3389		sequences.
3390
3391		U-Boot uses the following memory types:
3392		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
3393		- MPC824X: data cache
3394		- PPC4xx:  data cache
3395
3396- CONFIG_SYS_GBL_DATA_OFFSET:
3397
3398		Offset of the initial data structure in the memory
3399		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
3400		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
3401		data is located at the end of the available space
3402		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
3403		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
3404		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
3405		CONFIG_SYS_GBL_DATA_OFFSET) downward.
3406
3407	Note:
3408		On the MPC824X (or other systems that use the data
3409		cache for initial memory) the address chosen for
3410		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
3411		point to an otherwise UNUSED address space between
3412		the top of RAM and the start of the PCI space.
3413
3414- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
3415
3416- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
3417
3418- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
3419
3420- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
3421
3422- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
3423
3424- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
3425
3426- CONFIG_SYS_OR_TIMING_SDRAM:
3427		SDRAM timing
3428
3429- CONFIG_SYS_MAMR_PTA:
3430		periodic timer for refresh
3431
3432- CONFIG_SYS_DER:	Debug Event Register (37-47)
3433
3434- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
3435  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
3436  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
3437  CONFIG_SYS_BR1_PRELIM:
3438		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
3439
3440- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
3441  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
3442  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
3443		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
3444
3445- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
3446  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
3447		Machine Mode Register and Memory Periodic Timer
3448		Prescaler definitions (SDRAM timing)
3449
3450- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
3451		enable I2C microcode relocation patch (MPC8xx);
3452		define relocation offset in DPRAM [DSP2]
3453
3454- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
3455		enable SMC microcode relocation patch (MPC8xx);
3456		define relocation offset in DPRAM [SMC1]
3457
3458- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
3459		enable SPI microcode relocation patch (MPC8xx);
3460		define relocation offset in DPRAM [SCC4]
3461
3462- CONFIG_SYS_USE_OSCCLK:
3463		Use OSCM clock mode on MBX8xx board. Be careful,
3464		wrong setting might damage your board. Read
3465		doc/README.MBX before setting this variable!
3466
3467- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
3468		Offset of the bootmode word in DPRAM used by post
3469		(Power On Self Tests). This definition overrides
3470		#define'd default value in commproc.h resp.
3471		cpm_8260.h.
3472
3473- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
3474  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
3475  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
3476  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
3477  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
3478  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
3479  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
3480  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
3481		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
3482
3483- CONFIG_PCI_DISABLE_PCIE:
3484		Disable PCI-Express on systems where it is supported but not
3485		required.
3486
3487- CONFIG_PCI_ENUM_ONLY
3488		Only scan through and get the devices on the busses.
3489		Don't do any setup work, presumably because someone or
3490		something has already done it, and we don't need to do it
3491		a second time.	Useful for platforms that are pre-booted
3492		by coreboot or similar.
3493
3494- CONFIG_SYS_SRIO:
3495		Chip has SRIO or not
3496
3497- CONFIG_SRIO1:
3498		Board has SRIO 1 port available
3499
3500- CONFIG_SRIO2:
3501		Board has SRIO 2 port available
3502
3503- CONFIG_SYS_SRIOn_MEM_VIRT:
3504		Virtual Address of SRIO port 'n' memory region
3505
3506- CONFIG_SYS_SRIOn_MEM_PHYS:
3507		Physical Address of SRIO port 'n' memory region
3508
3509- CONFIG_SYS_SRIOn_MEM_SIZE:
3510		Size of SRIO port 'n' memory region
3511
3512- CONFIG_SYS_NDFC_16
3513		Defined to tell the NDFC that the NAND chip is using a
3514		16 bit bus.
3515
3516- CONFIG_SYS_NDFC_EBC0_CFG
3517		Sets the EBC0_CFG register for the NDFC. If not defined
3518		a default value will be used.
3519
3520- CONFIG_SPD_EEPROM
3521		Get DDR timing information from an I2C EEPROM. Common
3522		with pluggable memory modules such as SODIMMs
3523
3524  SPD_EEPROM_ADDRESS
3525		I2C address of the SPD EEPROM
3526
3527- CONFIG_SYS_SPD_BUS_NUM
3528		If SPD EEPROM is on an I2C bus other than the first
3529		one, specify here. Note that the value must resolve
3530		to something your driver can deal with.
3531
3532- CONFIG_SYS_DDR_RAW_TIMING
3533		Get DDR timing information from other than SPD. Common with
3534		soldered DDR chips onboard without SPD. DDR raw timing
3535		parameters are extracted from datasheet and hard-coded into
3536		header files or board specific files.
3537
3538- CONFIG_FSL_DDR_INTERACTIVE
3539		Enable interactive DDR debugging. See doc/README.fsl-ddr.
3540
3541- CONFIG_SYS_83XX_DDR_USES_CS0
3542		Only for 83xx systems. If specified, then DDR should
3543		be configured using CS0 and CS1 instead of CS2 and CS3.
3544
3545- CONFIG_ETHER_ON_FEC[12]
3546		Define to enable FEC[12] on a 8xx series processor.
3547
3548- CONFIG_FEC[12]_PHY
3549		Define to the hardcoded PHY address which corresponds
3550		to the given FEC; i. e.
3551			#define CONFIG_FEC1_PHY 4
3552		means that the PHY with address 4 is connected to FEC1
3553
3554		When set to -1, means to probe for first available.
3555
3556- CONFIG_FEC[12]_PHY_NORXERR
3557		The PHY does not have a RXERR line (RMII only).
3558		(so program the FEC to ignore it).
3559
3560- CONFIG_RMII
3561		Enable RMII mode for all FECs.
3562		Note that this is a global option, we can't
3563		have one FEC in standard MII mode and another in RMII mode.
3564
3565- CONFIG_CRC32_VERIFY
3566		Add a verify option to the crc32 command.
3567		The syntax is:
3568
3569		=> crc32 -v <address> <count> <crc32>
3570
3571		Where address/count indicate a memory area
3572		and crc32 is the correct crc32 which the
3573		area should have.
3574
3575- CONFIG_LOOPW
3576		Add the "loopw" memory command. This only takes effect if
3577		the memory commands are activated globally (CONFIG_CMD_MEM).
3578
3579- CONFIG_MX_CYCLIC
3580		Add the "mdc" and "mwc" memory commands. These are cyclic
3581		"md/mw" commands.
3582		Examples:
3583
3584		=> mdc.b 10 4 500
3585		This command will print 4 bytes (10,11,12,13) each 500 ms.
3586
3587		=> mwc.l 100 12345678 10
3588		This command will write 12345678 to address 100 all 10 ms.
3589
3590		This only takes effect if the memory commands are activated
3591		globally (CONFIG_CMD_MEM).
3592
3593- CONFIG_SKIP_LOWLEVEL_INIT
3594		[ARM, NDS32, MIPS only] If this variable is defined, then certain
3595		low level initializations (like setting up the memory
3596		controller) are omitted and/or U-Boot does not
3597		relocate itself into RAM.
3598
3599		Normally this variable MUST NOT be defined. The only
3600		exception is when U-Boot is loaded (to RAM) by some
3601		other boot loader or by a debugger which performs
3602		these initializations itself.
3603
3604- CONFIG_SPL_BUILD
3605		Modifies the behaviour of start.S when compiling a loader
3606		that is executed before the actual U-Boot. E.g. when
3607		compiling a NAND SPL.
3608
3609- CONFIG_USE_ARCH_MEMCPY
3610  CONFIG_USE_ARCH_MEMSET
3611		If these options are used a optimized version of memcpy/memset will
3612		be used if available. These functions may be faster under some
3613		conditions but may increase the binary size.
3614
3615Freescale QE/FMAN Firmware Support:
3616-----------------------------------
3617
3618The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
3619loading of "firmware", which is encoded in the QE firmware binary format.
3620This firmware often needs to be loaded during U-Boot booting, so macros
3621are used to identify the storage device (NOR flash, SPI, etc) and the address
3622within that device.
3623
3624- CONFIG_SYS_QE_FMAN_FW_ADDR
3625	The address in the storage device where the firmware is located.  The
3626	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
3627	is also specified.
3628
3629- CONFIG_SYS_QE_FMAN_FW_LENGTH
3630	The maximum possible size of the firmware.  The firmware binary format
3631	has a field that specifies the actual size of the firmware, but it
3632	might not be possible to read any part of the firmware unless some
3633	local storage is allocated to hold the entire firmware first.
3634
3635- CONFIG_SYS_QE_FMAN_FW_IN_NOR
3636	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
3637	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
3638	virtual address in NOR flash.
3639
3640- CONFIG_SYS_QE_FMAN_FW_IN_NAND
3641	Specifies that QE/FMAN firmware is located in NAND flash.
3642	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
3643
3644- CONFIG_SYS_QE_FMAN_FW_IN_MMC
3645	Specifies that QE/FMAN firmware is located on the primary SD/MMC
3646	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3647
3648- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
3649	Specifies that QE/FMAN firmware is located on the primary SPI
3650	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3651
3652- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
3653	Specifies that QE/FMAN firmware is located in the remote (master)
3654	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
3655	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
3656	window->master inbound window->master LAW->the ucode address in
3657	master's memory space.
3658
3659Building the Software:
3660======================
3661
3662Building U-Boot has been tested in several native build environments
3663and in many different cross environments. Of course we cannot support
3664all possibly existing versions of cross development tools in all
3665(potentially obsolete) versions. In case of tool chain problems we
3666recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
3667which is extensively used to build and test U-Boot.
3668
3669If you are not using a native environment, it is assumed that you
3670have GNU cross compiling tools available in your path. In this case,
3671you must set the environment variable CROSS_COMPILE in your shell.
3672Note that no changes to the Makefile or any other source files are
3673necessary. For example using the ELDK on a 4xx CPU, please enter:
3674
3675	$ CROSS_COMPILE=ppc_4xx-
3676	$ export CROSS_COMPILE
3677
3678Note: If you wish to generate Windows versions of the utilities in
3679      the tools directory you can use the MinGW toolchain
3680      (http://www.mingw.org).  Set your HOST tools to the MinGW
3681      toolchain and execute 'make tools'.  For example:
3682
3683       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
3684
3685      Binaries such as tools/mkimage.exe will be created which can
3686      be executed on computers running Windows.
3687
3688U-Boot is intended to be simple to build. After installing the
3689sources you must configure U-Boot for one specific board type. This
3690is done by typing:
3691
3692	make NAME_config
3693
3694where "NAME_config" is the name of one of the existing configu-
3695rations; see boards.cfg for supported names.
3696
3697Note: for some board special configuration names may exist; check if
3698      additional information is available from the board vendor; for
3699      instance, the TQM823L systems are available without (standard)
3700      or with LCD support. You can select such additional "features"
3701      when choosing the configuration, i. e.
3702
3703      make TQM823L_config
3704	- will configure for a plain TQM823L, i. e. no LCD support
3705
3706      make TQM823L_LCD_config
3707	- will configure for a TQM823L with U-Boot console on LCD
3708
3709      etc.
3710
3711
3712Finally, type "make all", and you should get some working U-Boot
3713images ready for download to / installation on your system:
3714
3715- "u-boot.bin" is a raw binary image
3716- "u-boot" is an image in ELF binary format
3717- "u-boot.srec" is in Motorola S-Record format
3718
3719By default the build is performed locally and the objects are saved
3720in the source directory. One of the two methods can be used to change
3721this behavior and build U-Boot to some external directory:
3722
37231. Add O= to the make command line invocations:
3724
3725	make O=/tmp/build distclean
3726	make O=/tmp/build NAME_config
3727	make O=/tmp/build all
3728
37292. Set environment variable BUILD_DIR to point to the desired location:
3730
3731	export BUILD_DIR=/tmp/build
3732	make distclean
3733	make NAME_config
3734	make all
3735
3736Note that the command line "O=" setting overrides the BUILD_DIR environment
3737variable.
3738
3739
3740Please be aware that the Makefiles assume you are using GNU make, so
3741for instance on NetBSD you might need to use "gmake" instead of
3742native "make".
3743
3744
3745If the system board that you have is not listed, then you will need
3746to port U-Boot to your hardware platform. To do this, follow these
3747steps:
3748
37491.  Add a new configuration option for your board to the toplevel
3750    "boards.cfg" file, using the existing entries as examples.
3751    Follow the instructions there to keep the boards in order.
37522.  Create a new directory to hold your board specific code. Add any
3753    files you need. In your board directory, you will need at least
3754    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
37553.  Create a new configuration file "include/configs/<board>.h" for
3756    your board
37573.  If you're porting U-Boot to a new CPU, then also create a new
3758    directory to hold your CPU specific code. Add any files you need.
37594.  Run "make <board>_config" with your new name.
37605.  Type "make", and you should get a working "u-boot.srec" file
3761    to be installed on your target system.
37626.  Debug and solve any problems that might arise.
3763    [Of course, this last step is much harder than it sounds.]
3764
3765
3766Testing of U-Boot Modifications, Ports to New Hardware, etc.:
3767==============================================================
3768
3769If you have modified U-Boot sources (for instance added a new board
3770or support for new devices, a new CPU, etc.) you are expected to
3771provide feedback to the other developers. The feedback normally takes
3772the form of a "patch", i. e. a context diff against a certain (latest
3773official or latest in the git repository) version of U-Boot sources.
3774
3775But before you submit such a patch, please verify that your modifi-
3776cation did not break existing code. At least make sure that *ALL* of
3777the supported boards compile WITHOUT ANY compiler warnings. To do so,
3778just run the "MAKEALL" script, which will configure and build U-Boot
3779for ALL supported system. Be warned, this will take a while. You can
3780select which (cross) compiler to use by passing a `CROSS_COMPILE'
3781environment variable to the script, i. e. to use the ELDK cross tools
3782you can type
3783
3784	CROSS_COMPILE=ppc_8xx- MAKEALL
3785
3786or to build on a native PowerPC system you can type
3787
3788	CROSS_COMPILE=' ' MAKEALL
3789
3790When using the MAKEALL script, the default behaviour is to build
3791U-Boot in the source directory. This location can be changed by
3792setting the BUILD_DIR environment variable. Also, for each target
3793built, the MAKEALL script saves two log files (<target>.ERR and
3794<target>.MAKEALL) in the <source dir>/LOG directory. This default
3795location can be changed by setting the MAKEALL_LOGDIR environment
3796variable. For example:
3797
3798	export BUILD_DIR=/tmp/build
3799	export MAKEALL_LOGDIR=/tmp/log
3800	CROSS_COMPILE=ppc_8xx- MAKEALL
3801
3802With the above settings build objects are saved in the /tmp/build,
3803log files are saved in the /tmp/log and the source tree remains clean
3804during the whole build process.
3805
3806
3807See also "U-Boot Porting Guide" below.
3808
3809
3810Monitor Commands - Overview:
3811============================
3812
3813go	- start application at address 'addr'
3814run	- run commands in an environment variable
3815bootm	- boot application image from memory
3816bootp	- boot image via network using BootP/TFTP protocol
3817bootz   - boot zImage from memory
3818tftpboot- boot image via network using TFTP protocol
3819	       and env variables "ipaddr" and "serverip"
3820	       (and eventually "gatewayip")
3821tftpput - upload a file via network using TFTP protocol
3822rarpboot- boot image via network using RARP/TFTP protocol
3823diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
3824loads	- load S-Record file over serial line
3825loadb	- load binary file over serial line (kermit mode)
3826md	- memory display
3827mm	- memory modify (auto-incrementing)
3828nm	- memory modify (constant address)
3829mw	- memory write (fill)
3830cp	- memory copy
3831cmp	- memory compare
3832crc32	- checksum calculation
3833i2c	- I2C sub-system
3834sspi	- SPI utility commands
3835base	- print or set address offset
3836printenv- print environment variables
3837setenv	- set environment variables
3838saveenv - save environment variables to persistent storage
3839protect - enable or disable FLASH write protection
3840erase	- erase FLASH memory
3841flinfo	- print FLASH memory information
3842bdinfo	- print Board Info structure
3843iminfo	- print header information for application image
3844coninfo - print console devices and informations
3845ide	- IDE sub-system
3846loop	- infinite loop on address range
3847loopw	- infinite write loop on address range
3848mtest	- simple RAM test
3849icache	- enable or disable instruction cache
3850dcache	- enable or disable data cache
3851reset	- Perform RESET of the CPU
3852echo	- echo args to console
3853version - print monitor version
3854help	- print online help
3855?	- alias for 'help'
3856
3857
3858Monitor Commands - Detailed Description:
3859========================================
3860
3861TODO.
3862
3863For now: just type "help <command>".
3864
3865
3866Environment Variables:
3867======================
3868
3869U-Boot supports user configuration using Environment Variables which
3870can be made persistent by saving to Flash memory.
3871
3872Environment Variables are set using "setenv", printed using
3873"printenv", and saved to Flash using "saveenv". Using "setenv"
3874without a value can be used to delete a variable from the
3875environment. As long as you don't save the environment you are
3876working with an in-memory copy. In case the Flash area containing the
3877environment is erased by accident, a default environment is provided.
3878
3879Some configuration options can be set using Environment Variables.
3880
3881List of environment variables (most likely not complete):
3882
3883  baudrate	- see CONFIG_BAUDRATE
3884
3885  bootdelay	- see CONFIG_BOOTDELAY
3886
3887  bootcmd	- see CONFIG_BOOTCOMMAND
3888
3889  bootargs	- Boot arguments when booting an RTOS image
3890
3891  bootfile	- Name of the image to load with TFTP
3892
3893  bootm_low	- Memory range available for image processing in the bootm
3894		  command can be restricted. This variable is given as
3895		  a hexadecimal number and defines lowest address allowed
3896		  for use by the bootm command. See also "bootm_size"
3897		  environment variable. Address defined by "bootm_low" is
3898		  also the base of the initial memory mapping for the Linux
3899		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
3900		  bootm_mapsize.
3901
3902  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
3903		  This variable is given as a hexadecimal number and it
3904		  defines the size of the memory region starting at base
3905		  address bootm_low that is accessible by the Linux kernel
3906		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
3907		  as the default value if it is defined, and bootm_size is
3908		  used otherwise.
3909
3910  bootm_size	- Memory range available for image processing in the bootm
3911		  command can be restricted. This variable is given as
3912		  a hexadecimal number and defines the size of the region
3913		  allowed for use by the bootm command. See also "bootm_low"
3914		  environment variable.
3915
3916  updatefile	- Location of the software update file on a TFTP server, used
3917		  by the automatic software update feature. Please refer to
3918		  documentation in doc/README.update for more details.
3919
3920  autoload	- if set to "no" (any string beginning with 'n'),
3921		  "bootp" will just load perform a lookup of the
3922		  configuration from the BOOTP server, but not try to
3923		  load any image using TFTP
3924
3925  autostart	- if set to "yes", an image loaded using the "bootp",
3926		  "rarpboot", "tftpboot" or "diskboot" commands will
3927		  be automatically started (by internally calling
3928		  "bootm")
3929
3930		  If set to "no", a standalone image passed to the
3931		  "bootm" command will be copied to the load address
3932		  (and eventually uncompressed), but NOT be started.
3933		  This can be used to load and uncompress arbitrary
3934		  data.
3935
3936  fdt_high	- if set this restricts the maximum address that the
3937		  flattened device tree will be copied into upon boot.
3938		  For example, if you have a system with 1 GB memory
3939		  at physical address 0x10000000, while Linux kernel
3940		  only recognizes the first 704 MB as low memory, you
3941		  may need to set fdt_high as 0x3C000000 to have the
3942		  device tree blob be copied to the maximum address
3943		  of the 704 MB low memory, so that Linux kernel can
3944		  access it during the boot procedure.
3945
3946		  If this is set to the special value 0xFFFFFFFF then
3947		  the fdt will not be copied at all on boot.  For this
3948		  to work it must reside in writable memory, have
3949		  sufficient padding on the end of it for u-boot to
3950		  add the information it needs into it, and the memory
3951		  must be accessible by the kernel.
3952
3953  fdtcontroladdr- if set this is the address of the control flattened
3954		  device tree used by U-Boot when CONFIG_OF_CONTROL is
3955		  defined.
3956
3957  i2cfast	- (PPC405GP|PPC405EP only)
3958		  if set to 'y' configures Linux I2C driver for fast
3959		  mode (400kHZ). This environment variable is used in
3960		  initialization code. So, for changes to be effective
3961		  it must be saved and board must be reset.
3962
3963  initrd_high	- restrict positioning of initrd images:
3964		  If this variable is not set, initrd images will be
3965		  copied to the highest possible address in RAM; this
3966		  is usually what you want since it allows for
3967		  maximum initrd size. If for some reason you want to
3968		  make sure that the initrd image is loaded below the
3969		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3970		  variable to a value of "no" or "off" or "0".
3971		  Alternatively, you can set it to a maximum upper
3972		  address to use (U-Boot will still check that it
3973		  does not overwrite the U-Boot stack and data).
3974
3975		  For instance, when you have a system with 16 MB
3976		  RAM, and want to reserve 4 MB from use by Linux,
3977		  you can do this by adding "mem=12M" to the value of
3978		  the "bootargs" variable. However, now you must make
3979		  sure that the initrd image is placed in the first
3980		  12 MB as well - this can be done with
3981
3982		  setenv initrd_high 00c00000
3983
3984		  If you set initrd_high to 0xFFFFFFFF, this is an
3985		  indication to U-Boot that all addresses are legal
3986		  for the Linux kernel, including addresses in flash
3987		  memory. In this case U-Boot will NOT COPY the
3988		  ramdisk at all. This may be useful to reduce the
3989		  boot time on your system, but requires that this
3990		  feature is supported by your Linux kernel.
3991
3992  ipaddr	- IP address; needed for tftpboot command
3993
3994  loadaddr	- Default load address for commands like "bootp",
3995		  "rarpboot", "tftpboot", "loadb" or "diskboot"
3996
3997  loads_echo	- see CONFIG_LOADS_ECHO
3998
3999  serverip	- TFTP server IP address; needed for tftpboot command
4000
4001  bootretry	- see CONFIG_BOOT_RETRY_TIME
4002
4003  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
4004
4005  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
4006
4007  ethprime	- controls which interface is used first.
4008
4009  ethact	- controls which interface is currently active.
4010		  For example you can do the following
4011
4012		  => setenv ethact FEC
4013		  => ping 192.168.0.1 # traffic sent on FEC
4014		  => setenv ethact SCC
4015		  => ping 10.0.0.1 # traffic sent on SCC
4016
4017  ethrotate	- When set to "no" U-Boot does not go through all
4018		  available network interfaces.
4019		  It just stays at the currently selected interface.
4020
4021  netretry	- When set to "no" each network operation will
4022		  either succeed or fail without retrying.
4023		  When set to "once" the network operation will
4024		  fail when all the available network interfaces
4025		  are tried once without success.
4026		  Useful on scripts which control the retry operation
4027		  themselves.
4028
4029  npe_ucode	- set load address for the NPE microcode
4030
4031  tftpsrcport	- If this is set, the value is used for TFTP's
4032		  UDP source port.
4033
4034  tftpdstport	- If this is set, the value is used for TFTP's UDP
4035		  destination port instead of the Well Know Port 69.
4036
4037  tftpblocksize - Block size to use for TFTP transfers; if not set,
4038		  we use the TFTP server's default block size
4039
4040  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
4041		  seconds, minimum value is 1000 = 1 second). Defines
4042		  when a packet is considered to be lost so it has to
4043		  be retransmitted. The default is 5000 = 5 seconds.
4044		  Lowering this value may make downloads succeed
4045		  faster in networks with high packet loss rates or
4046		  with unreliable TFTP servers.
4047
4048  vlan		- When set to a value < 4095 the traffic over
4049		  Ethernet is encapsulated/received over 802.1q
4050		  VLAN tagged frames.
4051
4052The following image location variables contain the location of images
4053used in booting. The "Image" column gives the role of the image and is
4054not an environment variable name. The other columns are environment
4055variable names. "File Name" gives the name of the file on a TFTP
4056server, "RAM Address" gives the location in RAM the image will be
4057loaded to, and "Flash Location" gives the image's address in NOR
4058flash or offset in NAND flash.
4059
4060*Note* - these variables don't have to be defined for all boards, some
4061boards currenlty use other variables for these purposes, and some
4062boards use these variables for other purposes.
4063
4064Image		    File Name	     RAM Address       Flash Location
4065-----		    ---------	     -----------       --------------
4066u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
4067Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
4068device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
4069ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
4070
4071The following environment variables may be used and automatically
4072updated by the network boot commands ("bootp" and "rarpboot"),
4073depending the information provided by your boot server:
4074
4075  bootfile	- see above
4076  dnsip		- IP address of your Domain Name Server
4077  dnsip2	- IP address of your secondary Domain Name Server
4078  gatewayip	- IP address of the Gateway (Router) to use
4079  hostname	- Target hostname
4080  ipaddr	- see above
4081  netmask	- Subnet Mask
4082  rootpath	- Pathname of the root filesystem on the NFS server
4083  serverip	- see above
4084
4085
4086There are two special Environment Variables:
4087
4088  serial#	- contains hardware identification information such
4089		  as type string and/or serial number
4090  ethaddr	- Ethernet address
4091
4092These variables can be set only once (usually during manufacturing of
4093the board). U-Boot refuses to delete or overwrite these variables
4094once they have been set once.
4095
4096
4097Further special Environment Variables:
4098
4099  ver		- Contains the U-Boot version string as printed
4100		  with the "version" command. This variable is
4101		  readonly (see CONFIG_VERSION_VARIABLE).
4102
4103
4104Please note that changes to some configuration parameters may take
4105only effect after the next boot (yes, that's just like Windoze :-).
4106
4107
4108Command Line Parsing:
4109=====================
4110
4111There are two different command line parsers available with U-Boot:
4112the old "simple" one, and the much more powerful "hush" shell:
4113
4114Old, simple command line parser:
4115--------------------------------
4116
4117- supports environment variables (through setenv / saveenv commands)
4118- several commands on one line, separated by ';'
4119- variable substitution using "... ${name} ..." syntax
4120- special characters ('$', ';') can be escaped by prefixing with '\',
4121  for example:
4122	setenv bootcmd bootm \${address}
4123- You can also escape text by enclosing in single apostrophes, for example:
4124	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
4125
4126Hush shell:
4127-----------
4128
4129- similar to Bourne shell, with control structures like
4130  if...then...else...fi, for...do...done; while...do...done,
4131  until...do...done, ...
4132- supports environment ("global") variables (through setenv / saveenv
4133  commands) and local shell variables (through standard shell syntax
4134  "name=value"); only environment variables can be used with "run"
4135  command
4136
4137General rules:
4138--------------
4139
4140(1) If a command line (or an environment variable executed by a "run"
4141    command) contains several commands separated by semicolon, and
4142    one of these commands fails, then the remaining commands will be
4143    executed anyway.
4144
4145(2) If you execute several variables with one call to run (i. e.
4146    calling run with a list of variables as arguments), any failing
4147    command will cause "run" to terminate, i. e. the remaining
4148    variables are not executed.
4149
4150Note for Redundant Ethernet Interfaces:
4151=======================================
4152
4153Some boards come with redundant Ethernet interfaces; U-Boot supports
4154such configurations and is capable of automatic selection of a
4155"working" interface when needed. MAC assignment works as follows:
4156
4157Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
4158MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
4159"eth1addr" (=>eth1), "eth2addr", ...
4160
4161If the network interface stores some valid MAC address (for instance
4162in SROM), this is used as default address if there is NO correspon-
4163ding setting in the environment; if the corresponding environment
4164variable is set, this overrides the settings in the card; that means:
4165
4166o If the SROM has a valid MAC address, and there is no address in the
4167  environment, the SROM's address is used.
4168
4169o If there is no valid address in the SROM, and a definition in the
4170  environment exists, then the value from the environment variable is
4171  used.
4172
4173o If both the SROM and the environment contain a MAC address, and
4174  both addresses are the same, this MAC address is used.
4175
4176o If both the SROM and the environment contain a MAC address, and the
4177  addresses differ, the value from the environment is used and a
4178  warning is printed.
4179
4180o If neither SROM nor the environment contain a MAC address, an error
4181  is raised.
4182
4183If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
4184will be programmed into hardware as part of the initialization process.	 This
4185may be skipped by setting the appropriate 'ethmacskip' environment variable.
4186The naming convention is as follows:
4187"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
4188
4189Image Formats:
4190==============
4191
4192U-Boot is capable of booting (and performing other auxiliary operations on)
4193images in two formats:
4194
4195New uImage format (FIT)
4196-----------------------
4197
4198Flexible and powerful format based on Flattened Image Tree -- FIT (similar
4199to Flattened Device Tree). It allows the use of images with multiple
4200components (several kernels, ramdisks, etc.), with contents protected by
4201SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
4202
4203
4204Old uImage format
4205-----------------
4206
4207Old image format is based on binary files which can be basically anything,
4208preceded by a special header; see the definitions in include/image.h for
4209details; basically, the header defines the following image properties:
4210
4211* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
4212  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
4213  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
4214  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
4215  INTEGRITY).
4216* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
4217  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
4218  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
4219* Compression Type (uncompressed, gzip, bzip2)
4220* Load Address
4221* Entry Point
4222* Image Name
4223* Image Timestamp
4224
4225The header is marked by a special Magic Number, and both the header
4226and the data portions of the image are secured against corruption by
4227CRC32 checksums.
4228
4229
4230Linux Support:
4231==============
4232
4233Although U-Boot should support any OS or standalone application
4234easily, the main focus has always been on Linux during the design of
4235U-Boot.
4236
4237U-Boot includes many features that so far have been part of some
4238special "boot loader" code within the Linux kernel. Also, any
4239"initrd" images to be used are no longer part of one big Linux image;
4240instead, kernel and "initrd" are separate images. This implementation
4241serves several purposes:
4242
4243- the same features can be used for other OS or standalone
4244  applications (for instance: using compressed images to reduce the
4245  Flash memory footprint)
4246
4247- it becomes much easier to port new Linux kernel versions because
4248  lots of low-level, hardware dependent stuff are done by U-Boot
4249
4250- the same Linux kernel image can now be used with different "initrd"
4251  images; of course this also means that different kernel images can
4252  be run with the same "initrd". This makes testing easier (you don't
4253  have to build a new "zImage.initrd" Linux image when you just
4254  change a file in your "initrd"). Also, a field-upgrade of the
4255  software is easier now.
4256
4257
4258Linux HOWTO:
4259============
4260
4261Porting Linux to U-Boot based systems:
4262---------------------------------------
4263
4264U-Boot cannot save you from doing all the necessary modifications to
4265configure the Linux device drivers for use with your target hardware
4266(no, we don't intend to provide a full virtual machine interface to
4267Linux :-).
4268
4269But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
4270
4271Just make sure your machine specific header file (for instance
4272include/asm-ppc/tqm8xx.h) includes the same definition of the Board
4273Information structure as we define in include/asm-<arch>/u-boot.h,
4274and make sure that your definition of IMAP_ADDR uses the same value
4275as your U-Boot configuration in CONFIG_SYS_IMMR.
4276
4277
4278Configuring the Linux kernel:
4279-----------------------------
4280
4281No specific requirements for U-Boot. Make sure you have some root
4282device (initial ramdisk, NFS) for your target system.
4283
4284
4285Building a Linux Image:
4286-----------------------
4287
4288With U-Boot, "normal" build targets like "zImage" or "bzImage" are
4289not used. If you use recent kernel source, a new build target
4290"uImage" will exist which automatically builds an image usable by
4291U-Boot. Most older kernels also have support for a "pImage" target,
4292which was introduced for our predecessor project PPCBoot and uses a
4293100% compatible format.
4294
4295Example:
4296
4297	make TQM850L_config
4298	make oldconfig
4299	make dep
4300	make uImage
4301
4302The "uImage" build target uses a special tool (in 'tools/mkimage') to
4303encapsulate a compressed Linux kernel image with header	 information,
4304CRC32 checksum etc. for use with U-Boot. This is what we are doing:
4305
4306* build a standard "vmlinux" kernel image (in ELF binary format):
4307
4308* convert the kernel into a raw binary image:
4309
4310	${CROSS_COMPILE}-objcopy -O binary \
4311				 -R .note -R .comment \
4312				 -S vmlinux linux.bin
4313
4314* compress the binary image:
4315
4316	gzip -9 linux.bin
4317
4318* package compressed binary image for U-Boot:
4319
4320	mkimage -A ppc -O linux -T kernel -C gzip \
4321		-a 0 -e 0 -n "Linux Kernel Image" \
4322		-d linux.bin.gz uImage
4323
4324
4325The "mkimage" tool can also be used to create ramdisk images for use
4326with U-Boot, either separated from the Linux kernel image, or
4327combined into one file. "mkimage" encapsulates the images with a 64
4328byte header containing information about target architecture,
4329operating system, image type, compression method, entry points, time
4330stamp, CRC32 checksums, etc.
4331
4332"mkimage" can be called in two ways: to verify existing images and
4333print the header information, or to build new images.
4334
4335In the first form (with "-l" option) mkimage lists the information
4336contained in the header of an existing U-Boot image; this includes
4337checksum verification:
4338
4339	tools/mkimage -l image
4340	  -l ==> list image header information
4341
4342The second form (with "-d" option) is used to build a U-Boot image
4343from a "data file" which is used as image payload:
4344
4345	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
4346		      -n name -d data_file image
4347	  -A ==> set architecture to 'arch'
4348	  -O ==> set operating system to 'os'
4349	  -T ==> set image type to 'type'
4350	  -C ==> set compression type 'comp'
4351	  -a ==> set load address to 'addr' (hex)
4352	  -e ==> set entry point to 'ep' (hex)
4353	  -n ==> set image name to 'name'
4354	  -d ==> use image data from 'datafile'
4355
4356Right now, all Linux kernels for PowerPC systems use the same load
4357address (0x00000000), but the entry point address depends on the
4358kernel version:
4359
4360- 2.2.x kernels have the entry point at 0x0000000C,
4361- 2.3.x and later kernels have the entry point at 0x00000000.
4362
4363So a typical call to build a U-Boot image would read:
4364
4365	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4366	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
4367	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
4368	> examples/uImage.TQM850L
4369	Image Name:   2.4.4 kernel for TQM850L
4370	Created:      Wed Jul 19 02:34:59 2000
4371	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
4372	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
4373	Load Address: 0x00000000
4374	Entry Point:  0x00000000
4375
4376To verify the contents of the image (or check for corruption):
4377
4378	-> tools/mkimage -l examples/uImage.TQM850L
4379	Image Name:   2.4.4 kernel for TQM850L
4380	Created:      Wed Jul 19 02:34:59 2000
4381	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
4382	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
4383	Load Address: 0x00000000
4384	Entry Point:  0x00000000
4385
4386NOTE: for embedded systems where boot time is critical you can trade
4387speed for memory and install an UNCOMPRESSED image instead: this
4388needs more space in Flash, but boots much faster since it does not
4389need to be uncompressed:
4390
4391	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
4392	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4393	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
4394	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
4395	> examples/uImage.TQM850L-uncompressed
4396	Image Name:   2.4.4 kernel for TQM850L
4397	Created:      Wed Jul 19 02:34:59 2000
4398	Image Type:   PowerPC Linux Kernel Image (uncompressed)
4399	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
4400	Load Address: 0x00000000
4401	Entry Point:  0x00000000
4402
4403
4404Similar you can build U-Boot images from a 'ramdisk.image.gz' file
4405when your kernel is intended to use an initial ramdisk:
4406
4407	-> tools/mkimage -n 'Simple Ramdisk Image' \
4408	> -A ppc -O linux -T ramdisk -C gzip \
4409	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
4410	Image Name:   Simple Ramdisk Image
4411	Created:      Wed Jan 12 14:01:50 2000
4412	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
4413	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
4414	Load Address: 0x00000000
4415	Entry Point:  0x00000000
4416
4417
4418Installing a Linux Image:
4419-------------------------
4420
4421To downloading a U-Boot image over the serial (console) interface,
4422you must convert the image to S-Record format:
4423
4424	objcopy -I binary -O srec examples/image examples/image.srec
4425
4426The 'objcopy' does not understand the information in the U-Boot
4427image header, so the resulting S-Record file will be relative to
4428address 0x00000000. To load it to a given address, you need to
4429specify the target address as 'offset' parameter with the 'loads'
4430command.
4431
4432Example: install the image to address 0x40100000 (which on the
4433TQM8xxL is in the first Flash bank):
4434
4435	=> erase 40100000 401FFFFF
4436
4437	.......... done
4438	Erased 8 sectors
4439
4440	=> loads 40100000
4441	## Ready for S-Record download ...
4442	~>examples/image.srec
4443	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
4444	...
4445	15989 15990 15991 15992
4446	[file transfer complete]
4447	[connected]
4448	## Start Addr = 0x00000000
4449
4450
4451You can check the success of the download using the 'iminfo' command;
4452this includes a checksum verification so you can be sure no data
4453corruption happened:
4454
4455	=> imi 40100000
4456
4457	## Checking Image at 40100000 ...
4458	   Image Name:	 2.2.13 for initrd on TQM850L
4459	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4460	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4461	   Load Address: 00000000
4462	   Entry Point:	 0000000c
4463	   Verifying Checksum ... OK
4464
4465
4466Boot Linux:
4467-----------
4468
4469The "bootm" command is used to boot an application that is stored in
4470memory (RAM or Flash). In case of a Linux kernel image, the contents
4471of the "bootargs" environment variable is passed to the kernel as
4472parameters. You can check and modify this variable using the
4473"printenv" and "setenv" commands:
4474
4475
4476	=> printenv bootargs
4477	bootargs=root=/dev/ram
4478
4479	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4480
4481	=> printenv bootargs
4482	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4483
4484	=> bootm 40020000
4485	## Booting Linux kernel at 40020000 ...
4486	   Image Name:	 2.2.13 for NFS on TQM850L
4487	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4488	   Data Size:	 381681 Bytes = 372 kB = 0 MB
4489	   Load Address: 00000000
4490	   Entry Point:	 0000000c
4491	   Verifying Checksum ... OK
4492	   Uncompressing Kernel Image ... OK
4493	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
4494	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4495	time_init: decrementer frequency = 187500000/60
4496	Calibrating delay loop... 49.77 BogoMIPS
4497	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
4498	...
4499
4500If you want to boot a Linux kernel with initial RAM disk, you pass
4501the memory addresses of both the kernel and the initrd image (PPBCOOT
4502format!) to the "bootm" command:
4503
4504	=> imi 40100000 40200000
4505
4506	## Checking Image at 40100000 ...
4507	   Image Name:	 2.2.13 for initrd on TQM850L
4508	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4509	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4510	   Load Address: 00000000
4511	   Entry Point:	 0000000c
4512	   Verifying Checksum ... OK
4513
4514	## Checking Image at 40200000 ...
4515	   Image Name:	 Simple Ramdisk Image
4516	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
4517	   Data Size:	 566530 Bytes = 553 kB = 0 MB
4518	   Load Address: 00000000
4519	   Entry Point:	 00000000
4520	   Verifying Checksum ... OK
4521
4522	=> bootm 40100000 40200000
4523	## Booting Linux kernel at 40100000 ...
4524	   Image Name:	 2.2.13 for initrd on TQM850L
4525	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4526	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4527	   Load Address: 00000000
4528	   Entry Point:	 0000000c
4529	   Verifying Checksum ... OK
4530	   Uncompressing Kernel Image ... OK
4531	## Loading RAMDisk Image at 40200000 ...
4532	   Image Name:	 Simple Ramdisk Image
4533	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
4534	   Data Size:	 566530 Bytes = 553 kB = 0 MB
4535	   Load Address: 00000000
4536	   Entry Point:	 00000000
4537	   Verifying Checksum ... OK
4538	   Loading Ramdisk ... OK
4539	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
4540	Boot arguments: root=/dev/ram
4541	time_init: decrementer frequency = 187500000/60
4542	Calibrating delay loop... 49.77 BogoMIPS
4543	...
4544	RAMDISK: Compressed image found at block 0
4545	VFS: Mounted root (ext2 filesystem).
4546
4547	bash#
4548
4549Boot Linux and pass a flat device tree:
4550-----------
4551
4552First, U-Boot must be compiled with the appropriate defines. See the section
4553titled "Linux Kernel Interface" above for a more in depth explanation. The
4554following is an example of how to start a kernel and pass an updated
4555flat device tree:
4556
4557=> print oftaddr
4558oftaddr=0x300000
4559=> print oft
4560oft=oftrees/mpc8540ads.dtb
4561=> tftp $oftaddr $oft
4562Speed: 1000, full duplex
4563Using TSEC0 device
4564TFTP from server 192.168.1.1; our IP address is 192.168.1.101
4565Filename 'oftrees/mpc8540ads.dtb'.
4566Load address: 0x300000
4567Loading: #
4568done
4569Bytes transferred = 4106 (100a hex)
4570=> tftp $loadaddr $bootfile
4571Speed: 1000, full duplex
4572Using TSEC0 device
4573TFTP from server 192.168.1.1; our IP address is 192.168.1.2
4574Filename 'uImage'.
4575Load address: 0x200000
4576Loading:############
4577done
4578Bytes transferred = 1029407 (fb51f hex)
4579=> print loadaddr
4580loadaddr=200000
4581=> print oftaddr
4582oftaddr=0x300000
4583=> bootm $loadaddr - $oftaddr
4584## Booting image at 00200000 ...
4585   Image Name:	 Linux-2.6.17-dirty
4586   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4587   Data Size:	 1029343 Bytes = 1005.2 kB
4588   Load Address: 00000000
4589   Entry Point:	 00000000
4590   Verifying Checksum ... OK
4591   Uncompressing Kernel Image ... OK
4592Booting using flat device tree at 0x300000
4593Using MPC85xx ADS machine description
4594Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
4595[snip]
4596
4597
4598More About U-Boot Image Types:
4599------------------------------
4600
4601U-Boot supports the following image types:
4602
4603   "Standalone Programs" are directly runnable in the environment
4604	provided by U-Boot; it is expected that (if they behave
4605	well) you can continue to work in U-Boot after return from
4606	the Standalone Program.
4607   "OS Kernel Images" are usually images of some Embedded OS which
4608	will take over control completely. Usually these programs
4609	will install their own set of exception handlers, device
4610	drivers, set up the MMU, etc. - this means, that you cannot
4611	expect to re-enter U-Boot except by resetting the CPU.
4612   "RAMDisk Images" are more or less just data blocks, and their
4613	parameters (address, size) are passed to an OS kernel that is
4614	being started.
4615   "Multi-File Images" contain several images, typically an OS
4616	(Linux) kernel image and one or more data images like
4617	RAMDisks. This construct is useful for instance when you want
4618	to boot over the network using BOOTP etc., where the boot
4619	server provides just a single image file, but you want to get
4620	for instance an OS kernel and a RAMDisk image.
4621
4622	"Multi-File Images" start with a list of image sizes, each
4623	image size (in bytes) specified by an "uint32_t" in network
4624	byte order. This list is terminated by an "(uint32_t)0".
4625	Immediately after the terminating 0 follow the images, one by
4626	one, all aligned on "uint32_t" boundaries (size rounded up to
4627	a multiple of 4 bytes).
4628
4629   "Firmware Images" are binary images containing firmware (like
4630	U-Boot or FPGA images) which usually will be programmed to
4631	flash memory.
4632
4633   "Script files" are command sequences that will be executed by
4634	U-Boot's command interpreter; this feature is especially
4635	useful when you configure U-Boot to use a real shell (hush)
4636	as command interpreter.
4637
4638Booting the Linux zImage:
4639-------------------------
4640
4641On some platforms, it's possible to boot Linux zImage. This is done
4642using the "bootz" command. The syntax of "bootz" command is the same
4643as the syntax of "bootm" command.
4644
4645Note, defining the CONFIG_SUPPORT_INITRD_RAW allows user to supply
4646kernel with raw initrd images. The syntax is slightly different, the
4647address of the initrd must be augmented by it's size, in the following
4648format: "<initrd addres>:<initrd size>".
4649
4650
4651Standalone HOWTO:
4652=================
4653
4654One of the features of U-Boot is that you can dynamically load and
4655run "standalone" applications, which can use some resources of
4656U-Boot like console I/O functions or interrupt services.
4657
4658Two simple examples are included with the sources:
4659
4660"Hello World" Demo:
4661-------------------
4662
4663'examples/hello_world.c' contains a small "Hello World" Demo
4664application; it is automatically compiled when you build U-Boot.
4665It's configured to run at address 0x00040004, so you can play with it
4666like that:
4667
4668	=> loads
4669	## Ready for S-Record download ...
4670	~>examples/hello_world.srec
4671	1 2 3 4 5 6 7 8 9 10 11 ...
4672	[file transfer complete]
4673	[connected]
4674	## Start Addr = 0x00040004
4675
4676	=> go 40004 Hello World! This is a test.
4677	## Starting application at 0x00040004 ...
4678	Hello World
4679	argc = 7
4680	argv[0] = "40004"
4681	argv[1] = "Hello"
4682	argv[2] = "World!"
4683	argv[3] = "This"
4684	argv[4] = "is"
4685	argv[5] = "a"
4686	argv[6] = "test."
4687	argv[7] = "<NULL>"
4688	Hit any key to exit ...
4689
4690	## Application terminated, rc = 0x0
4691
4692Another example, which demonstrates how to register a CPM interrupt
4693handler with the U-Boot code, can be found in 'examples/timer.c'.
4694Here, a CPM timer is set up to generate an interrupt every second.
4695The interrupt service routine is trivial, just printing a '.'
4696character, but this is just a demo program. The application can be
4697controlled by the following keys:
4698
4699	? - print current values og the CPM Timer registers
4700	b - enable interrupts and start timer
4701	e - stop timer and disable interrupts
4702	q - quit application
4703
4704	=> loads
4705	## Ready for S-Record download ...
4706	~>examples/timer.srec
4707	1 2 3 4 5 6 7 8 9 10 11 ...
4708	[file transfer complete]
4709	[connected]
4710	## Start Addr = 0x00040004
4711
4712	=> go 40004
4713	## Starting application at 0x00040004 ...
4714	TIMERS=0xfff00980
4715	Using timer 1
4716	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
4717
4718Hit 'b':
4719	[q, b, e, ?] Set interval 1000000 us
4720	Enabling timer
4721Hit '?':
4722	[q, b, e, ?] ........
4723	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
4724Hit '?':
4725	[q, b, e, ?] .
4726	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
4727Hit '?':
4728	[q, b, e, ?] .
4729	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
4730Hit '?':
4731	[q, b, e, ?] .
4732	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
4733Hit 'e':
4734	[q, b, e, ?] ...Stopping timer
4735Hit 'q':
4736	[q, b, e, ?] ## Application terminated, rc = 0x0
4737
4738
4739Minicom warning:
4740================
4741
4742Over time, many people have reported problems when trying to use the
4743"minicom" terminal emulation program for serial download. I (wd)
4744consider minicom to be broken, and recommend not to use it. Under
4745Unix, I recommend to use C-Kermit for general purpose use (and
4746especially for kermit binary protocol download ("loadb" command), and
4747use "cu" for S-Record download ("loads" command).  See
4748http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
4749for help with kermit.
4750
4751
4752Nevertheless, if you absolutely want to use it try adding this
4753configuration to your "File transfer protocols" section:
4754
4755	   Name	   Program			Name U/D FullScr IO-Red. Multi
4756	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
4757	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
4758
4759
4760NetBSD Notes:
4761=============
4762
4763Starting at version 0.9.2, U-Boot supports NetBSD both as host
4764(build U-Boot) and target system (boots NetBSD/mpc8xx).
4765
4766Building requires a cross environment; it is known to work on
4767NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
4768need gmake since the Makefiles are not compatible with BSD make).
4769Note that the cross-powerpc package does not install include files;
4770attempting to build U-Boot will fail because <machine/ansi.h> is
4771missing.  This file has to be installed and patched manually:
4772
4773	# cd /usr/pkg/cross/powerpc-netbsd/include
4774	# mkdir powerpc
4775	# ln -s powerpc machine
4776	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
4777	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
4778
4779Native builds *don't* work due to incompatibilities between native
4780and U-Boot include files.
4781
4782Booting assumes that (the first part of) the image booted is a
4783stage-2 loader which in turn loads and then invokes the kernel
4784proper. Loader sources will eventually appear in the NetBSD source
4785tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
4786meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
4787
4788
4789Implementation Internals:
4790=========================
4791
4792The following is not intended to be a complete description of every
4793implementation detail. However, it should help to understand the
4794inner workings of U-Boot and make it easier to port it to custom
4795hardware.
4796
4797
4798Initial Stack, Global Data:
4799---------------------------
4800
4801The implementation of U-Boot is complicated by the fact that U-Boot
4802starts running out of ROM (flash memory), usually without access to
4803system RAM (because the memory controller is not initialized yet).
4804This means that we don't have writable Data or BSS segments, and BSS
4805is not initialized as zero. To be able to get a C environment working
4806at all, we have to allocate at least a minimal stack. Implementation
4807options for this are defined and restricted by the CPU used: Some CPU
4808models provide on-chip memory (like the IMMR area on MPC8xx and
4809MPC826x processors), on others (parts of) the data cache can be
4810locked as (mis-) used as memory, etc.
4811
4812	Chris Hallinan posted a good summary of these issues to the
4813	U-Boot mailing list:
4814
4815	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
4816	From: "Chris Hallinan" <clh@net1plus.com>
4817	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
4818	...
4819
4820	Correct me if I'm wrong, folks, but the way I understand it
4821	is this: Using DCACHE as initial RAM for Stack, etc, does not
4822	require any physical RAM backing up the cache. The cleverness
4823	is that the cache is being used as a temporary supply of
4824	necessary storage before the SDRAM controller is setup. It's
4825	beyond the scope of this list to explain the details, but you
4826	can see how this works by studying the cache architecture and
4827	operation in the architecture and processor-specific manuals.
4828
4829	OCM is On Chip Memory, which I believe the 405GP has 4K. It
4830	is another option for the system designer to use as an
4831	initial stack/RAM area prior to SDRAM being available. Either
4832	option should work for you. Using CS 4 should be fine if your
4833	board designers haven't used it for something that would
4834	cause you grief during the initial boot! It is frequently not
4835	used.
4836
4837	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
4838	with your processor/board/system design. The default value
4839	you will find in any recent u-boot distribution in
4840	walnut.h should work for you. I'd set it to a value larger
4841	than your SDRAM module. If you have a 64MB SDRAM module, set
4842	it above 400_0000. Just make sure your board has no resources
4843	that are supposed to respond to that address! That code in
4844	start.S has been around a while and should work as is when
4845	you get the config right.
4846
4847	-Chris Hallinan
4848	DS4.COM, Inc.
4849
4850It is essential to remember this, since it has some impact on the C
4851code for the initialization procedures:
4852
4853* Initialized global data (data segment) is read-only. Do not attempt
4854  to write it.
4855
4856* Do not use any uninitialized global data (or implicitely initialized
4857  as zero data - BSS segment) at all - this is undefined, initiali-
4858  zation is performed later (when relocating to RAM).
4859
4860* Stack space is very limited. Avoid big data buffers or things like
4861  that.
4862
4863Having only the stack as writable memory limits means we cannot use
4864normal global data to share information beween the code. But it
4865turned out that the implementation of U-Boot can be greatly
4866simplified by making a global data structure (gd_t) available to all
4867functions. We could pass a pointer to this data as argument to _all_
4868functions, but this would bloat the code. Instead we use a feature of
4869the GCC compiler (Global Register Variables) to share the data: we
4870place a pointer (gd) to the global data into a register which we
4871reserve for this purpose.
4872
4873When choosing a register for such a purpose we are restricted by the
4874relevant  (E)ABI  specifications for the current architecture, and by
4875GCC's implementation.
4876
4877For PowerPC, the following registers have specific use:
4878	R1:	stack pointer
4879	R2:	reserved for system use
4880	R3-R4:	parameter passing and return values
4881	R5-R10: parameter passing
4882	R13:	small data area pointer
4883	R30:	GOT pointer
4884	R31:	frame pointer
4885
4886	(U-Boot also uses R12 as internal GOT pointer. r12
4887	is a volatile register so r12 needs to be reset when
4888	going back and forth between asm and C)
4889
4890    ==> U-Boot will use R2 to hold a pointer to the global data
4891
4892    Note: on PPC, we could use a static initializer (since the
4893    address of the global data structure is known at compile time),
4894    but it turned out that reserving a register results in somewhat
4895    smaller code - although the code savings are not that big (on
4896    average for all boards 752 bytes for the whole U-Boot image,
4897    624 text + 127 data).
4898
4899On Blackfin, the normal C ABI (except for P3) is followed as documented here:
4900	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
4901
4902    ==> U-Boot will use P3 to hold a pointer to the global data
4903
4904On ARM, the following registers are used:
4905
4906	R0:	function argument word/integer result
4907	R1-R3:	function argument word
4908	R9:	GOT pointer
4909	R10:	stack limit (used only if stack checking if enabled)
4910	R11:	argument (frame) pointer
4911	R12:	temporary workspace
4912	R13:	stack pointer
4913	R14:	link register
4914	R15:	program counter
4915
4916    ==> U-Boot will use R8 to hold a pointer to the global data
4917
4918On Nios II, the ABI is documented here:
4919	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
4920
4921    ==> U-Boot will use gp to hold a pointer to the global data
4922
4923    Note: on Nios II, we give "-G0" option to gcc and don't use gp
4924    to access small data sections, so gp is free.
4925
4926On NDS32, the following registers are used:
4927
4928	R0-R1:	argument/return
4929	R2-R5:	argument
4930	R15:	temporary register for assembler
4931	R16:	trampoline register
4932	R28:	frame pointer (FP)
4933	R29:	global pointer (GP)
4934	R30:	link register (LP)
4935	R31:	stack pointer (SP)
4936	PC:	program counter (PC)
4937
4938    ==> U-Boot will use R10 to hold a pointer to the global data
4939
4940NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
4941or current versions of GCC may "optimize" the code too much.
4942
4943Memory Management:
4944------------------
4945
4946U-Boot runs in system state and uses physical addresses, i.e. the
4947MMU is not used either for address mapping nor for memory protection.
4948
4949The available memory is mapped to fixed addresses using the memory
4950controller. In this process, a contiguous block is formed for each
4951memory type (Flash, SDRAM, SRAM), even when it consists of several
4952physical memory banks.
4953
4954U-Boot is installed in the first 128 kB of the first Flash bank (on
4955TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
4956booting and sizing and initializing DRAM, the code relocates itself
4957to the upper end of DRAM. Immediately below the U-Boot code some
4958memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
4959configuration setting]. Below that, a structure with global Board
4960Info data is placed, followed by the stack (growing downward).
4961
4962Additionally, some exception handler code is copied to the low 8 kB
4963of DRAM (0x00000000 ... 0x00001FFF).
4964
4965So a typical memory configuration with 16 MB of DRAM could look like
4966this:
4967
4968	0x0000 0000	Exception Vector code
4969	      :
4970	0x0000 1FFF
4971	0x0000 2000	Free for Application Use
4972	      :
4973	      :
4974
4975	      :
4976	      :
4977	0x00FB FF20	Monitor Stack (Growing downward)
4978	0x00FB FFAC	Board Info Data and permanent copy of global data
4979	0x00FC 0000	Malloc Arena
4980	      :
4981	0x00FD FFFF
4982	0x00FE 0000	RAM Copy of Monitor Code
4983	...		eventually: LCD or video framebuffer
4984	...		eventually: pRAM (Protected RAM - unchanged by reset)
4985	0x00FF FFFF	[End of RAM]
4986
4987
4988System Initialization:
4989----------------------
4990
4991In the reset configuration, U-Boot starts at the reset entry point
4992(on most PowerPC systems at address 0x00000100). Because of the reset
4993configuration for CS0# this is a mirror of the onboard Flash memory.
4994To be able to re-map memory U-Boot then jumps to its link address.
4995To be able to implement the initialization code in C, a (small!)
4996initial stack is set up in the internal Dual Ported RAM (in case CPUs
4997which provide such a feature like MPC8xx or MPC8260), or in a locked
4998part of the data cache. After that, U-Boot initializes the CPU core,
4999the caches and the SIU.
5000
5001Next, all (potentially) available memory banks are mapped using a
5002preliminary mapping. For example, we put them on 512 MB boundaries
5003(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
5004on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
5005programmed for SDRAM access. Using the temporary configuration, a
5006simple memory test is run that determines the size of the SDRAM
5007banks.
5008
5009When there is more than one SDRAM bank, and the banks are of
5010different size, the largest is mapped first. For equal size, the first
5011bank (CS2#) is mapped first. The first mapping is always for address
50120x00000000, with any additional banks following immediately to create
5013contiguous memory starting from 0.
5014
5015Then, the monitor installs itself at the upper end of the SDRAM area
5016and allocates memory for use by malloc() and for the global Board
5017Info data; also, the exception vector code is copied to the low RAM
5018pages, and the final stack is set up.
5019
5020Only after this relocation will you have a "normal" C environment;
5021until that you are restricted in several ways, mostly because you are
5022running from ROM, and because the code will have to be relocated to a
5023new address in RAM.
5024
5025
5026U-Boot Porting Guide:
5027----------------------
5028
5029[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
5030list, October 2002]
5031
5032
5033int main(int argc, char *argv[])
5034{
5035	sighandler_t no_more_time;
5036
5037	signal(SIGALRM, no_more_time);
5038	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
5039
5040	if (available_money > available_manpower) {
5041		Pay consultant to port U-Boot;
5042		return 0;
5043	}
5044
5045	Download latest U-Boot source;
5046
5047	Subscribe to u-boot mailing list;
5048
5049	if (clueless)
5050		email("Hi, I am new to U-Boot, how do I get started?");
5051
5052	while (learning) {
5053		Read the README file in the top level directory;
5054		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
5055		Read applicable doc/*.README;
5056		Read the source, Luke;
5057		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
5058	}
5059
5060	if (available_money > toLocalCurrency ($2500))
5061		Buy a BDI3000;
5062	else
5063		Add a lot of aggravation and time;
5064
5065	if (a similar board exists) {	/* hopefully... */
5066		cp -a board/<similar> board/<myboard>
5067		cp include/configs/<similar>.h include/configs/<myboard>.h
5068	} else {
5069		Create your own board support subdirectory;
5070		Create your own board include/configs/<myboard>.h file;
5071	}
5072	Edit new board/<myboard> files
5073	Edit new include/configs/<myboard>.h
5074
5075	while (!accepted) {
5076		while (!running) {
5077			do {
5078				Add / modify source code;
5079			} until (compiles);
5080			Debug;
5081			if (clueless)
5082				email("Hi, I am having problems...");
5083		}
5084		Send patch file to the U-Boot email list;
5085		if (reasonable critiques)
5086			Incorporate improvements from email list code review;
5087		else
5088			Defend code as written;
5089	}
5090
5091	return 0;
5092}
5093
5094void no_more_time (int sig)
5095{
5096      hire_a_guru();
5097}
5098
5099
5100Coding Standards:
5101-----------------
5102
5103All contributions to U-Boot should conform to the Linux kernel
5104coding style; see the file "Documentation/CodingStyle" and the script
5105"scripts/Lindent" in your Linux kernel source directory.
5106
5107Source files originating from a different project (for example the
5108MTD subsystem) are generally exempt from these guidelines and are not
5109reformated to ease subsequent migration to newer versions of those
5110sources.
5111
5112Please note that U-Boot is implemented in C (and to some small parts in
5113Assembler); no C++ is used, so please do not use C++ style comments (//)
5114in your code.
5115
5116Please also stick to the following formatting rules:
5117- remove any trailing white space
5118- use TAB characters for indentation and vertical alignment, not spaces
5119- make sure NOT to use DOS '\r\n' line feeds
5120- do not add more than 2 consecutive empty lines to source files
5121- do not add trailing empty lines to source files
5122
5123Submissions which do not conform to the standards may be returned
5124with a request to reformat the changes.
5125
5126
5127Submitting Patches:
5128-------------------
5129
5130Since the number of patches for U-Boot is growing, we need to
5131establish some rules. Submissions which do not conform to these rules
5132may be rejected, even when they contain important and valuable stuff.
5133
5134Please see http://www.denx.de/wiki/U-Boot/Patches for details.
5135
5136Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
5137see http://lists.denx.de/mailman/listinfo/u-boot
5138
5139When you send a patch, please include the following information with
5140it:
5141
5142* For bug fixes: a description of the bug and how your patch fixes
5143  this bug. Please try to include a way of demonstrating that the
5144  patch actually fixes something.
5145
5146* For new features: a description of the feature and your
5147  implementation.
5148
5149* A CHANGELOG entry as plaintext (separate from the patch)
5150
5151* For major contributions, your entry to the CREDITS file
5152
5153* When you add support for a new board, don't forget to add this
5154  board to the MAINTAINERS file, too.
5155
5156* If your patch adds new configuration options, don't forget to
5157  document these in the README file.
5158
5159* The patch itself. If you are using git (which is *strongly*
5160  recommended) you can easily generate the patch using the
5161  "git format-patch". If you then use "git send-email" to send it to
5162  the U-Boot mailing list, you will avoid most of the common problems
5163  with some other mail clients.
5164
5165  If you cannot use git, use "diff -purN OLD NEW". If your version of
5166  diff does not support these options, then get the latest version of
5167  GNU diff.
5168
5169  The current directory when running this command shall be the parent
5170  directory of the U-Boot source tree (i. e. please make sure that
5171  your patch includes sufficient directory information for the
5172  affected files).
5173
5174  We prefer patches as plain text. MIME attachments are discouraged,
5175  and compressed attachments must not be used.
5176
5177* If one logical set of modifications affects or creates several
5178  files, all these changes shall be submitted in a SINGLE patch file.
5179
5180* Changesets that contain different, unrelated modifications shall be
5181  submitted as SEPARATE patches, one patch per changeset.
5182
5183
5184Notes:
5185
5186* Before sending the patch, run the MAKEALL script on your patched
5187  source tree and make sure that no errors or warnings are reported
5188  for any of the boards.
5189
5190* Keep your modifications to the necessary minimum: A patch
5191  containing several unrelated changes or arbitrary reformats will be
5192  returned with a request to re-formatting / split it.
5193
5194* If you modify existing code, make sure that your new code does not
5195  add to the memory footprint of the code ;-) Small is beautiful!
5196  When adding new features, these should compile conditionally only
5197  (using #ifdef), and the resulting code with the new feature
5198  disabled must not need more memory than the old code without your
5199  modification.
5200
5201* Remember that there is a size limit of 100 kB per message on the
5202  u-boot mailing list. Bigger patches will be moderated. If they are
5203  reasonable and not too big, they will be acknowledged. But patches
5204  bigger than the size limit should be avoided.
5205