xref: /rk3399_rockchip-uboot/README (revision eafc8db0e35275330f43a4cf7b7ae8aba71c9728)
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_FSL_TBCLK_DIV
367
368		Defines the core time base clock divider ratio compared to the
369		system clock.  On most PQ3 devices this is 8, on newer QorIQ
370		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
371
372		CONFIG_SYS_FSL_PCIE_COMPAT
373
374		Defines the string to utilize when trying to match PCIe device
375		tree nodes for the given platform.
376
377- Generic CPU options:
378		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
379
380		Defines the endianess of the CPU. Implementation of those
381		values is arch specific.
382
383- Intel Monahans options:
384		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
385
386		Defines the Monahans run mode to oscillator
387		ratio. Valid values are 8, 16, 24, 31. The core
388		frequency is this value multiplied by 13 MHz.
389
390		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
391
392		Defines the Monahans turbo mode to oscillator
393		ratio. Valid values are 1 (default if undefined) and
394		2. The core frequency as calculated above is multiplied
395		by this value.
396
397- MIPS CPU options:
398		CONFIG_SYS_INIT_SP_OFFSET
399
400		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
401		pointer. This is needed for the temporary stack before
402		relocation.
403
404		CONFIG_SYS_MIPS_CACHE_MODE
405
406		Cache operation mode for the MIPS CPU.
407		See also arch/mips/include/asm/mipsregs.h.
408		Possible values are:
409			CONF_CM_CACHABLE_NO_WA
410			CONF_CM_CACHABLE_WA
411			CONF_CM_UNCACHED
412			CONF_CM_CACHABLE_NONCOHERENT
413			CONF_CM_CACHABLE_CE
414			CONF_CM_CACHABLE_COW
415			CONF_CM_CACHABLE_CUW
416			CONF_CM_CACHABLE_ACCELERATED
417
418		CONFIG_SYS_XWAY_EBU_BOOTCFG
419
420		Special option for Lantiq XWAY SoCs for booting from NOR flash.
421		See also arch/mips/cpu/mips32/start.S.
422
423		CONFIG_XWAY_SWAP_BYTES
424
425		Enable compilation of tools/xway-swap-bytes needed for Lantiq
426		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
427		be swapped if a flash programmer is used.
428
429- ARM options:
430		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
431
432		Select high exception vectors of the ARM core, e.g., do not
433		clear the V bit of the c1 register of CP15.
434
435		CONFIG_SYS_THUMB_BUILD
436
437		Use this flag to build U-Boot using the Thumb instruction
438		set for ARM architectures. Thumb instruction set provides
439		better code density. For ARM architectures that support
440		Thumb2 this flag will result in Thumb2 code generated by
441		GCC.
442
443- Linux Kernel Interface:
444		CONFIG_CLOCKS_IN_MHZ
445
446		U-Boot stores all clock information in Hz
447		internally. For binary compatibility with older Linux
448		kernels (which expect the clocks passed in the
449		bd_info data to be in MHz) the environment variable
450		"clocks_in_mhz" can be defined so that U-Boot
451		converts clock data to MHZ before passing it to the
452		Linux kernel.
453		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
454		"clocks_in_mhz=1" is automatically included in the
455		default environment.
456
457		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
458
459		When transferring memsize parameter to linux, some versions
460		expect it to be in bytes, others in MB.
461		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
462
463		CONFIG_OF_LIBFDT
464
465		New kernel versions are expecting firmware settings to be
466		passed using flattened device trees (based on open firmware
467		concepts).
468
469		CONFIG_OF_LIBFDT
470		 * New libfdt-based support
471		 * Adds the "fdt" command
472		 * The bootm command automatically updates the fdt
473
474		OF_CPU - The proper name of the cpus node (only required for
475			MPC512X and MPC5xxx based boards).
476		OF_SOC - The proper name of the soc node (only required for
477			MPC512X and MPC5xxx based boards).
478		OF_TBCLK - The timebase frequency.
479		OF_STDOUT_PATH - The path to the console device
480
481		boards with QUICC Engines require OF_QE to set UCC MAC
482		addresses
483
484		CONFIG_OF_BOARD_SETUP
485
486		Board code has addition modification that it wants to make
487		to the flat device tree before handing it off to the kernel
488
489		CONFIG_OF_BOOT_CPU
490
491		This define fills in the correct boot CPU in the boot
492		param header, the default value is zero if undefined.
493
494		CONFIG_OF_IDE_FIXUP
495
496		U-Boot can detect if an IDE device is present or not.
497		If not, and this new config option is activated, U-Boot
498		removes the ATA node from the DTS before booting Linux,
499		so the Linux IDE driver does not probe the device and
500		crash. This is needed for buggy hardware (uc101) where
501		no pull down resistor is connected to the signal IDE5V_DD7.
502
503		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
504
505		This setting is mandatory for all boards that have only one
506		machine type and must be used to specify the machine type
507		number as it appears in the ARM machine registry
508		(see http://www.arm.linux.org.uk/developer/machines/).
509		Only boards that have multiple machine types supported
510		in a single configuration file and the machine type is
511		runtime discoverable, do not have to use this setting.
512
513- vxWorks boot parameters:
514
515		bootvx constructs a valid bootline using the following
516		environments variables: bootfile, ipaddr, serverip, hostname.
517		It loads the vxWorks image pointed bootfile.
518
519		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
520		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
521		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
522		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
523
524		CONFIG_SYS_VXWORKS_ADD_PARAMS
525
526		Add it at the end of the bootline. E.g "u=username pw=secret"
527
528		Note: If a "bootargs" environment is defined, it will overwride
529		the defaults discussed just above.
530
531- Cache Configuration:
532		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
533		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
534		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
535
536- Cache Configuration for ARM:
537		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
538				      controller
539		CONFIG_SYS_PL310_BASE - Physical base address of PL310
540					controller register space
541
542- Serial Ports:
543		CONFIG_PL010_SERIAL
544
545		Define this if you want support for Amba PrimeCell PL010 UARTs.
546
547		CONFIG_PL011_SERIAL
548
549		Define this if you want support for Amba PrimeCell PL011 UARTs.
550
551		CONFIG_PL011_CLOCK
552
553		If you have Amba PrimeCell PL011 UARTs, set this variable to
554		the clock speed of the UARTs.
555
556		CONFIG_PL01x_PORTS
557
558		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
559		define this to a list of base addresses for each (supported)
560		port. See e.g. include/configs/versatile.h
561
562		CONFIG_PL011_SERIAL_RLCR
563
564		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
565		have separate receive and transmit line control registers.  Set
566		this variable to initialize the extra register.
567
568		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
569
570		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
571		boot loader that has already initialized the UART.  Define this
572		variable to flush the UART at init time.
573
574
575- Console Interface:
576		Depending on board, define exactly one serial port
577		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
578		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
579		console by defining CONFIG_8xx_CONS_NONE
580
581		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
582		port routines must be defined elsewhere
583		(i.e. serial_init(), serial_getc(), ...)
584
585		CONFIG_CFB_CONSOLE
586		Enables console device for a color framebuffer. Needs following
587		defines (cf. smiLynxEM, i8042)
588			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
589						(default big endian)
590			VIDEO_HW_RECTFILL	graphic chip supports
591						rectangle fill
592						(cf. smiLynxEM)
593			VIDEO_HW_BITBLT		graphic chip supports
594						bit-blit (cf. smiLynxEM)
595			VIDEO_VISIBLE_COLS	visible pixel columns
596						(cols=pitch)
597			VIDEO_VISIBLE_ROWS	visible pixel rows
598			VIDEO_PIXEL_SIZE	bytes per pixel
599			VIDEO_DATA_FORMAT	graphic data format
600						(0-5, cf. cfb_console.c)
601			VIDEO_FB_ADRS		framebuffer address
602			VIDEO_KBD_INIT_FCT	keyboard int fct
603						(i.e. i8042_kbd_init())
604			VIDEO_TSTC_FCT		test char fct
605						(i.e. i8042_tstc)
606			VIDEO_GETC_FCT		get char fct
607						(i.e. i8042_getc)
608			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
609						(requires blink timer
610						cf. i8042.c)
611			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
612			CONFIG_CONSOLE_TIME	display time/date info in
613						upper right corner
614						(requires CONFIG_CMD_DATE)
615			CONFIG_VIDEO_LOGO	display Linux logo in
616						upper left corner
617			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
618						linux_logo.h for logo.
619						Requires CONFIG_VIDEO_LOGO
620			CONFIG_CONSOLE_EXTRA_INFO
621						additional board info beside
622						the logo
623
624		When CONFIG_CFB_CONSOLE is defined, video console is
625		default i/o. Serial console can be forced with
626		environment 'console=serial'.
627
628		When CONFIG_SILENT_CONSOLE is defined, all console
629		messages (by U-Boot and Linux!) can be silenced with
630		the "silent" environment variable. See
631		doc/README.silent for more information.
632
633- Console Baudrate:
634		CONFIG_BAUDRATE - in bps
635		Select one of the baudrates listed in
636		CONFIG_SYS_BAUDRATE_TABLE, see below.
637		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
638
639- Console Rx buffer length
640		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
641		the maximum receive buffer length for the SMC.
642		This option is actual only for 82xx and 8xx possible.
643		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
644		must be defined, to setup the maximum idle timeout for
645		the SMC.
646
647- Pre-Console Buffer:
648		Prior to the console being initialised (i.e. serial UART
649		initialised etc) all console output is silently discarded.
650		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
651		buffer any console messages prior to the console being
652		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
653		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
654		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
655		bytes are output before the console is initialised, the
656		earlier bytes are discarded.
657
658		'Sane' compilers will generate smaller code if
659		CONFIG_PRE_CON_BUF_SZ is a power of 2
660
661- Safe printf() functions
662		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
663		the printf() functions. These are defined in
664		include/vsprintf.h and include snprintf(), vsnprintf() and
665		so on. Code size increase is approximately 300-500 bytes.
666		If this option is not given then these functions will
667		silently discard their buffer size argument - this means
668		you are not getting any overflow checking in this case.
669
670- Boot Delay:	CONFIG_BOOTDELAY - in seconds
671		Delay before automatically booting the default image;
672		set to -1 to disable autoboot.
673
674		See doc/README.autoboot for these options that
675		work with CONFIG_BOOTDELAY. None are required.
676		CONFIG_BOOT_RETRY_TIME
677		CONFIG_BOOT_RETRY_MIN
678		CONFIG_AUTOBOOT_KEYED
679		CONFIG_AUTOBOOT_PROMPT
680		CONFIG_AUTOBOOT_DELAY_STR
681		CONFIG_AUTOBOOT_STOP_STR
682		CONFIG_AUTOBOOT_DELAY_STR2
683		CONFIG_AUTOBOOT_STOP_STR2
684		CONFIG_ZERO_BOOTDELAY_CHECK
685		CONFIG_RESET_TO_RETRY
686
687- Autoboot Command:
688		CONFIG_BOOTCOMMAND
689		Only needed when CONFIG_BOOTDELAY is enabled;
690		define a command string that is automatically executed
691		when no character is read on the console interface
692		within "Boot Delay" after reset.
693
694		CONFIG_BOOTARGS
695		This can be used to pass arguments to the bootm
696		command. The value of CONFIG_BOOTARGS goes into the
697		environment value "bootargs".
698
699		CONFIG_RAMBOOT and CONFIG_NFSBOOT
700		The value of these goes into the environment as
701		"ramboot" and "nfsboot" respectively, and can be used
702		as a convenience, when switching between booting from
703		RAM and NFS.
704
705- Pre-Boot Commands:
706		CONFIG_PREBOOT
707
708		When this option is #defined, the existence of the
709		environment variable "preboot" will be checked
710		immediately before starting the CONFIG_BOOTDELAY
711		countdown and/or running the auto-boot command resp.
712		entering interactive mode.
713
714		This feature is especially useful when "preboot" is
715		automatically generated or modified. For an example
716		see the LWMON board specific code: here "preboot" is
717		modified when the user holds down a certain
718		combination of keys on the (special) keyboard when
719		booting the systems
720
721- Serial Download Echo Mode:
722		CONFIG_LOADS_ECHO
723		If defined to 1, all characters received during a
724		serial download (using the "loads" command) are
725		echoed back. This might be needed by some terminal
726		emulations (like "cu"), but may as well just take
727		time on others. This setting #define's the initial
728		value of the "loads_echo" environment variable.
729
730- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
731		CONFIG_KGDB_BAUDRATE
732		Select one of the baudrates listed in
733		CONFIG_SYS_BAUDRATE_TABLE, see below.
734
735- Monitor Functions:
736		Monitor commands can be included or excluded
737		from the build by using the #include files
738		"config_cmd_all.h" and #undef'ing unwanted
739		commands, or using "config_cmd_default.h"
740		and augmenting with additional #define's
741		for wanted commands.
742
743		The default command configuration includes all commands
744		except those marked below with a "*".
745
746		CONFIG_CMD_ASKENV	* ask for env variable
747		CONFIG_CMD_BDI		  bdinfo
748		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
749		CONFIG_CMD_BMP		* BMP support
750		CONFIG_CMD_BSP		* Board specific commands
751		CONFIG_CMD_BOOTD	  bootd
752		CONFIG_CMD_CACHE	* icache, dcache
753		CONFIG_CMD_CONSOLE	  coninfo
754		CONFIG_CMD_CRC32	* crc32
755		CONFIG_CMD_DATE		* support for RTC, date/time...
756		CONFIG_CMD_DHCP		* DHCP support
757		CONFIG_CMD_DIAG		* Diagnostics
758		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
759		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
760		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
761		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
762		CONFIG_CMD_DTT		* Digital Therm and Thermostat
763		CONFIG_CMD_ECHO		  echo arguments
764		CONFIG_CMD_EDITENV	  edit env variable
765		CONFIG_CMD_EEPROM	* EEPROM read/write support
766		CONFIG_CMD_ELF		* bootelf, bootvx
767		CONFIG_CMD_EXPORTENV	* export the environment
768		CONFIG_CMD_SAVEENV	  saveenv
769		CONFIG_CMD_FDC		* Floppy Disk Support
770		CONFIG_CMD_FAT		* FAT partition support
771		CONFIG_CMD_FDOS		* Dos diskette Support
772		CONFIG_CMD_FLASH	  flinfo, erase, protect
773		CONFIG_CMD_FPGA		  FPGA device initialization support
774		CONFIG_CMD_GO		* the 'go' command (exec code)
775		CONFIG_CMD_GREPENV	* search environment
776		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
777		CONFIG_CMD_I2C		* I2C serial bus support
778		CONFIG_CMD_IDE		* IDE harddisk support
779		CONFIG_CMD_IMI		  iminfo
780		CONFIG_CMD_IMLS		  List all found images
781		CONFIG_CMD_IMMAP	* IMMR dump support
782		CONFIG_CMD_IMPORTENV	* import an environment
783		CONFIG_CMD_IRQ		* irqinfo
784		CONFIG_CMD_ITEST	  Integer/string test of 2 values
785		CONFIG_CMD_JFFS2	* JFFS2 Support
786		CONFIG_CMD_KGDB		* kgdb
787		CONFIG_CMD_LDRINFO	  ldrinfo (display Blackfin loader)
788		CONFIG_CMD_LOADB	  loadb
789		CONFIG_CMD_LOADS	  loads
790		CONFIG_CMD_MD5SUM	  print md5 message digest
791					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
792		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
793					  loop, loopw, mtest
794		CONFIG_CMD_MISC		  Misc functions like sleep etc
795		CONFIG_CMD_MMC		* MMC memory mapped support
796		CONFIG_CMD_MII		* MII utility commands
797		CONFIG_CMD_MTDPARTS	* MTD partition support
798		CONFIG_CMD_NAND		* NAND support
799		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
800		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
801		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
802		CONFIG_CMD_PCI		* pciinfo
803		CONFIG_CMD_PCMCIA		* PCMCIA support
804		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
805					  host
806		CONFIG_CMD_PORTIO	* Port I/O
807		CONFIG_CMD_REGINFO	* Register dump
808		CONFIG_CMD_RUN		  run command in env variable
809		CONFIG_CMD_SAVES	* save S record dump
810		CONFIG_CMD_SCSI		* SCSI Support
811		CONFIG_CMD_SDRAM	* print SDRAM configuration information
812					  (requires CONFIG_CMD_I2C)
813		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
814					  (4xx only)
815		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
816		CONFIG_CMD_SHA1SUM	  print sha1 memory digest
817					  (requires CONFIG_CMD_MEMORY)
818		CONFIG_CMD_SOURCE	  "source" command Support
819		CONFIG_CMD_SPI		* SPI serial bus support
820		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
821		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
822		CONFIG_CMD_TIME		* run command and report execution time
823		CONFIG_CMD_USB		* USB support
824		CONFIG_CMD_CDP		* Cisco Discover Protocol support
825		CONFIG_CMD_MFSL		* Microblaze FSL support
826
827
828		EXAMPLE: If you want all functions except of network
829		support you can write:
830
831		#include "config_cmd_all.h"
832		#undef CONFIG_CMD_NET
833
834	Other Commands:
835		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
836
837	Note:	Don't enable the "icache" and "dcache" commands
838		(configuration option CONFIG_CMD_CACHE) unless you know
839		what you (and your U-Boot users) are doing. Data
840		cache cannot be enabled on systems like the 8xx or
841		8260 (where accesses to the IMMR region must be
842		uncached), and it cannot be disabled on all other
843		systems where we (mis-) use the data cache to hold an
844		initial stack and some data.
845
846
847		XXX - this list needs to get updated!
848
849- Device tree:
850		CONFIG_OF_CONTROL
851		If this variable is defined, U-Boot will use a device tree
852		to configure its devices, instead of relying on statically
853		compiled #defines in the board file. This option is
854		experimental and only available on a few boards. The device
855		tree is available in the global data as gd->fdt_blob.
856
857		U-Boot needs to get its device tree from somewhere. This can
858		be done using one of the two options below:
859
860		CONFIG_OF_EMBED
861		If this variable is defined, U-Boot will embed a device tree
862		binary in its image. This device tree file should be in the
863		board directory and called <soc>-<board>.dts. The binary file
864		is then picked up in board_init_f() and made available through
865		the global data structure as gd->blob.
866
867		CONFIG_OF_SEPARATE
868		If this variable is defined, U-Boot will build a device tree
869		binary. It will be called u-boot.dtb. Architecture-specific
870		code will locate it at run-time. Generally this works by:
871
872			cat u-boot.bin u-boot.dtb >image.bin
873
874		and in fact, U-Boot does this for you, creating a file called
875		u-boot-dtb.bin which is useful in the common case. You can
876		still use the individual files if you need something more
877		exotic.
878
879- Watchdog:
880		CONFIG_WATCHDOG
881		If this variable is defined, it enables watchdog
882		support for the SoC. There must be support in the SoC
883		specific code for a watchdog. For the 8xx and 8260
884		CPUs, the SIU Watchdog feature is enabled in the SYPCR
885		register.  When supported for a specific SoC is
886		available, then no further board specific code should
887		be needed to use it.
888
889		CONFIG_HW_WATCHDOG
890		When using a watchdog circuitry external to the used
891		SoC, then define this variable and provide board
892		specific code for the "hw_watchdog_reset" function.
893
894- U-Boot Version:
895		CONFIG_VERSION_VARIABLE
896		If this variable is defined, an environment variable
897		named "ver" is created by U-Boot showing the U-Boot
898		version as printed by the "version" command.
899		This variable is readonly.
900
901- Real-Time Clock:
902
903		When CONFIG_CMD_DATE is selected, the type of the RTC
904		has to be selected, too. Define exactly one of the
905		following options:
906
907		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
908		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
909		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
910		CONFIG_RTC_MC146818	- use MC146818 RTC
911		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
912		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
913		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
914		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
915		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
916		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
917		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
918		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
919					  RV3029 RTC.
920
921		Note that if the RTC uses I2C, then the I2C interface
922		must also be configured. See I2C Support, below.
923
924- GPIO Support:
925		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
926		CONFIG_PCA953X_INFO	- enable pca953x info command
927
928		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
929		chip-ngpio pairs that tell the PCA953X driver the number of
930		pins supported by a particular chip.
931
932		Note that if the GPIO device uses I2C, then the I2C interface
933		must also be configured. See I2C Support, below.
934
935- Timestamp Support:
936
937		When CONFIG_TIMESTAMP is selected, the timestamp
938		(date and time) of an image is printed by image
939		commands like bootm or iminfo. This option is
940		automatically enabled when you select CONFIG_CMD_DATE .
941
942- Partition Support:
943		CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
944		and/or CONFIG_ISO_PARTITION and/or CONFIG_EFI_PARTITION
945
946		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
947		CONFIG_CMD_SCSI) you must configure support for at
948		least one partition type as well.
949
950- IDE Reset method:
951		CONFIG_IDE_RESET_ROUTINE - this is defined in several
952		board configurations files but used nowhere!
953
954		CONFIG_IDE_RESET - is this is defined, IDE Reset will
955		be performed by calling the function
956			ide_set_reset(int reset)
957		which has to be defined in a board specific file
958
959- ATAPI Support:
960		CONFIG_ATAPI
961
962		Set this to enable ATAPI support.
963
964- LBA48 Support
965		CONFIG_LBA48
966
967		Set this to enable support for disks larger than 137GB
968		Also look at CONFIG_SYS_64BIT_LBA.
969		Whithout these , LBA48 support uses 32bit variables and will 'only'
970		support disks up to 2.1TB.
971
972		CONFIG_SYS_64BIT_LBA:
973			When enabled, makes the IDE subsystem use 64bit sector addresses.
974			Default is 32bit.
975
976- SCSI Support:
977		At the moment only there is only support for the
978		SYM53C8XX SCSI controller; define
979		CONFIG_SCSI_SYM53C8XX to enable it.
980
981		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
982		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
983		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
984		maximum numbers of LUNs, SCSI ID's and target
985		devices.
986		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
987
988- NETWORK Support (PCI):
989		CONFIG_E1000
990		Support for Intel 8254x/8257x gigabit chips.
991
992		CONFIG_E1000_SPI
993		Utility code for direct access to the SPI bus on Intel 8257x.
994		This does not do anything useful unless you set at least one
995		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
996
997		CONFIG_E1000_SPI_GENERIC
998		Allow generic access to the SPI bus on the Intel 8257x, for
999		example with the "sspi" command.
1000
1001		CONFIG_CMD_E1000
1002		Management command for E1000 devices.  When used on devices
1003		with SPI support you can reprogram the EEPROM from U-Boot.
1004
1005		CONFIG_E1000_FALLBACK_MAC
1006		default MAC for empty EEPROM after production.
1007
1008		CONFIG_EEPRO100
1009		Support for Intel 82557/82559/82559ER chips.
1010		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1011		write routine for first time initialisation.
1012
1013		CONFIG_TULIP
1014		Support for Digital 2114x chips.
1015		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1016		modem chip initialisation (KS8761/QS6611).
1017
1018		CONFIG_NATSEMI
1019		Support for National dp83815 chips.
1020
1021		CONFIG_NS8382X
1022		Support for National dp8382[01] gigabit chips.
1023
1024- NETWORK Support (other):
1025
1026		CONFIG_DRIVER_AT91EMAC
1027		Support for AT91RM9200 EMAC.
1028
1029			CONFIG_RMII
1030			Define this to use reduced MII inteface
1031
1032			CONFIG_DRIVER_AT91EMAC_QUIET
1033			If this defined, the driver is quiet.
1034			The driver doen't show link status messages.
1035
1036		CONFIG_CALXEDA_XGMAC
1037		Support for the Calxeda XGMAC device
1038
1039		CONFIG_DRIVER_LAN91C96
1040		Support for SMSC's LAN91C96 chips.
1041
1042			CONFIG_LAN91C96_BASE
1043			Define this to hold the physical address
1044			of the LAN91C96's I/O space
1045
1046			CONFIG_LAN91C96_USE_32_BIT
1047			Define this to enable 32 bit addressing
1048
1049		CONFIG_DRIVER_SMC91111
1050		Support for SMSC's LAN91C111 chip
1051
1052			CONFIG_SMC91111_BASE
1053			Define this to hold the physical address
1054			of the device (I/O space)
1055
1056			CONFIG_SMC_USE_32_BIT
1057			Define this if data bus is 32 bits
1058
1059			CONFIG_SMC_USE_IOFUNCS
1060			Define this to use i/o functions instead of macros
1061			(some hardware wont work with macros)
1062
1063		CONFIG_DRIVER_TI_EMAC
1064		Support for davinci emac
1065
1066			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1067			Define this if you have more then 3 PHYs.
1068
1069		CONFIG_FTGMAC100
1070		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1071
1072			CONFIG_FTGMAC100_EGIGA
1073			Define this to use GE link update with gigabit PHY.
1074			Define this if FTGMAC100 is connected to gigabit PHY.
1075			If your system has 10/100 PHY only, it might not occur
1076			wrong behavior. Because PHY usually return timeout or
1077			useless data when polling gigabit status and gigabit
1078			control registers. This behavior won't affect the
1079			correctnessof 10/100 link speed update.
1080
1081		CONFIG_SMC911X
1082		Support for SMSC's LAN911x and LAN921x chips
1083
1084			CONFIG_SMC911X_BASE
1085			Define this to hold the physical address
1086			of the device (I/O space)
1087
1088			CONFIG_SMC911X_32_BIT
1089			Define this if data bus is 32 bits
1090
1091			CONFIG_SMC911X_16_BIT
1092			Define this if data bus is 16 bits. If your processor
1093			automatically converts one 32 bit word to two 16 bit
1094			words you may also try CONFIG_SMC911X_32_BIT.
1095
1096		CONFIG_SH_ETHER
1097		Support for Renesas on-chip Ethernet controller
1098
1099			CONFIG_SH_ETHER_USE_PORT
1100			Define the number of ports to be used
1101
1102			CONFIG_SH_ETHER_PHY_ADDR
1103			Define the ETH PHY's address
1104
1105			CONFIG_SH_ETHER_CACHE_WRITEBACK
1106			If this option is set, the driver enables cache flush.
1107
1108- TPM Support:
1109		CONFIG_GENERIC_LPC_TPM
1110		Support for generic parallel port TPM devices. Only one device
1111		per system is supported at this time.
1112
1113			CONFIG_TPM_TIS_BASE_ADDRESS
1114			Base address where the generic TPM device is mapped
1115			to. Contemporary x86 systems usually map it at
1116			0xfed40000.
1117
1118- USB Support:
1119		At the moment only the UHCI host controller is
1120		supported (PIP405, MIP405, MPC5200); define
1121		CONFIG_USB_UHCI to enable it.
1122		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1123		and define CONFIG_USB_STORAGE to enable the USB
1124		storage devices.
1125		Note:
1126		Supported are USB Keyboards and USB Floppy drives
1127		(TEAC FD-05PUB).
1128		MPC5200 USB requires additional defines:
1129			CONFIG_USB_CLOCK
1130				for 528 MHz Clock: 0x0001bbbb
1131			CONFIG_PSC3_USB
1132				for USB on PSC3
1133			CONFIG_USB_CONFIG
1134				for differential drivers: 0x00001000
1135				for single ended drivers: 0x00005000
1136				for differential drivers on PSC3: 0x00000100
1137				for single ended drivers on PSC3: 0x00004100
1138			CONFIG_SYS_USB_EVENT_POLL
1139				May be defined to allow interrupt polling
1140				instead of using asynchronous interrupts
1141
1142		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1143		txfilltuning field in the EHCI controller on reset.
1144
1145- USB Device:
1146		Define the below if you wish to use the USB console.
1147		Once firmware is rebuilt from a serial console issue the
1148		command "setenv stdin usbtty; setenv stdout usbtty" and
1149		attach your USB cable. The Unix command "dmesg" should print
1150		it has found a new device. The environment variable usbtty
1151		can be set to gserial or cdc_acm to enable your device to
1152		appear to a USB host as a Linux gserial device or a
1153		Common Device Class Abstract Control Model serial device.
1154		If you select usbtty = gserial you should be able to enumerate
1155		a Linux host by
1156		# modprobe usbserial vendor=0xVendorID product=0xProductID
1157		else if using cdc_acm, simply setting the environment
1158		variable usbtty to be cdc_acm should suffice. The following
1159		might be defined in YourBoardName.h
1160
1161			CONFIG_USB_DEVICE
1162			Define this to build a UDC device
1163
1164			CONFIG_USB_TTY
1165			Define this to have a tty type of device available to
1166			talk to the UDC device
1167
1168			CONFIG_USBD_HS
1169			Define this to enable the high speed support for usb
1170			device and usbtty. If this feature is enabled, a routine
1171			int is_usbd_high_speed(void)
1172			also needs to be defined by the driver to dynamically poll
1173			whether the enumeration has succeded at high speed or full
1174			speed.
1175
1176			CONFIG_SYS_CONSOLE_IS_IN_ENV
1177			Define this if you want stdin, stdout &/or stderr to
1178			be set to usbtty.
1179
1180			mpc8xx:
1181				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1182				Derive USB clock from external clock "blah"
1183				- CONFIG_SYS_USB_EXTC_CLK 0x02
1184
1185				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1186				Derive USB clock from brgclk
1187				- CONFIG_SYS_USB_BRG_CLK 0x04
1188
1189		If you have a USB-IF assigned VendorID then you may wish to
1190		define your own vendor specific values either in BoardName.h
1191		or directly in usbd_vendor_info.h. If you don't define
1192		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1193		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1194		should pretend to be a Linux device to it's target host.
1195
1196			CONFIG_USBD_MANUFACTURER
1197			Define this string as the name of your company for
1198			- CONFIG_USBD_MANUFACTURER "my company"
1199
1200			CONFIG_USBD_PRODUCT_NAME
1201			Define this string as the name of your product
1202			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1203
1204			CONFIG_USBD_VENDORID
1205			Define this as your assigned Vendor ID from the USB
1206			Implementors Forum. This *must* be a genuine Vendor ID
1207			to avoid polluting the USB namespace.
1208			- CONFIG_USBD_VENDORID 0xFFFF
1209
1210			CONFIG_USBD_PRODUCTID
1211			Define this as the unique Product ID
1212			for your device
1213			- CONFIG_USBD_PRODUCTID 0xFFFF
1214
1215- ULPI Layer Support:
1216		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1217		the generic ULPI layer. The generic layer accesses the ULPI PHY
1218		via the platform viewport, so you need both the genric layer and
1219		the viewport enabled. Currently only Chipidea/ARC based
1220		viewport is supported.
1221		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1222		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1223
1224- MMC Support:
1225		The MMC controller on the Intel PXA is supported. To
1226		enable this define CONFIG_MMC. The MMC can be
1227		accessed from the boot prompt by mapping the device
1228		to physical memory similar to flash. Command line is
1229		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1230		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1231
1232		CONFIG_SH_MMCIF
1233		Support for Renesas on-chip MMCIF controller
1234
1235			CONFIG_SH_MMCIF_ADDR
1236			Define the base address of MMCIF registers
1237
1238			CONFIG_SH_MMCIF_CLK
1239			Define the clock frequency for MMCIF
1240
1241- Journaling Flash filesystem support:
1242		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1243		CONFIG_JFFS2_NAND_DEV
1244		Define these for a default partition on a NAND device
1245
1246		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1247		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1248		Define these for a default partition on a NOR device
1249
1250		CONFIG_SYS_JFFS_CUSTOM_PART
1251		Define this to create an own partition. You have to provide a
1252		function struct part_info* jffs2_part_info(int part_num)
1253
1254		If you define only one JFFS2 partition you may also want to
1255		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1256		to disable the command chpart. This is the default when you
1257		have not defined a custom partition
1258
1259- FAT(File Allocation Table) filesystem write function support:
1260		CONFIG_FAT_WRITE
1261
1262		Define this to enable support for saving memory data as a
1263		file in FAT formatted partition.
1264
1265		This will also enable the command "fatwrite" enabling the
1266		user to write files to FAT.
1267
1268- Keyboard Support:
1269		CONFIG_ISA_KEYBOARD
1270
1271		Define this to enable standard (PC-Style) keyboard
1272		support
1273
1274		CONFIG_I8042_KBD
1275		Standard PC keyboard driver with US (is default) and
1276		GERMAN key layout (switch via environment 'keymap=de') support.
1277		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1278		for cfb_console. Supports cursor blinking.
1279
1280- Video support:
1281		CONFIG_VIDEO
1282
1283		Define this to enable video support (for output to
1284		video).
1285
1286		CONFIG_VIDEO_CT69000
1287
1288		Enable Chips & Technologies 69000 Video chip
1289
1290		CONFIG_VIDEO_SMI_LYNXEM
1291		Enable Silicon Motion SMI 712/710/810 Video chip. The
1292		video output is selected via environment 'videoout'
1293		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1294		assumed.
1295
1296		For the CT69000 and SMI_LYNXEM drivers, videomode is
1297		selected via environment 'videomode'. Two different ways
1298		are possible:
1299		- "videomode=num"   'num' is a standard LiLo mode numbers.
1300		Following standard modes are supported	(* is default):
1301
1302		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1303		-------------+---------------------------------------------
1304		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1305		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1306		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1307		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1308		-------------+---------------------------------------------
1309		(i.e. setenv videomode 317; saveenv; reset;)
1310
1311		- "videomode=bootargs" all the video parameters are parsed
1312		from the bootargs. (See drivers/video/videomodes.c)
1313
1314
1315		CONFIG_VIDEO_SED13806
1316		Enable Epson SED13806 driver. This driver supports 8bpp
1317		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1318		or CONFIG_VIDEO_SED13806_16BPP
1319
1320		CONFIG_FSL_DIU_FB
1321		Enable the Freescale DIU video driver.	Reference boards for
1322		SOCs that have a DIU should define this macro to enable DIU
1323		support, and should also define these other macros:
1324
1325			CONFIG_SYS_DIU_ADDR
1326			CONFIG_VIDEO
1327			CONFIG_CMD_BMP
1328			CONFIG_CFB_CONSOLE
1329			CONFIG_VIDEO_SW_CURSOR
1330			CONFIG_VGA_AS_SINGLE_DEVICE
1331			CONFIG_VIDEO_LOGO
1332			CONFIG_VIDEO_BMP_LOGO
1333
1334		The DIU driver will look for the 'video-mode' environment
1335		variable, and if defined, enable the DIU as a console during
1336		boot.  See the documentation file README.video for a
1337		description of this variable.
1338
1339- Keyboard Support:
1340		CONFIG_KEYBOARD
1341
1342		Define this to enable a custom keyboard support.
1343		This simply calls drv_keyboard_init() which must be
1344		defined in your board-specific files.
1345		The only board using this so far is RBC823.
1346
1347- LCD Support:	CONFIG_LCD
1348
1349		Define this to enable LCD support (for output to LCD
1350		display); also select one of the supported displays
1351		by defining one of these:
1352
1353		CONFIG_ATMEL_LCD:
1354
1355			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1356
1357		CONFIG_NEC_NL6448AC33:
1358
1359			NEC NL6448AC33-18. Active, color, single scan.
1360
1361		CONFIG_NEC_NL6448BC20
1362
1363			NEC NL6448BC20-08. 6.5", 640x480.
1364			Active, color, single scan.
1365
1366		CONFIG_NEC_NL6448BC33_54
1367
1368			NEC NL6448BC33-54. 10.4", 640x480.
1369			Active, color, single scan.
1370
1371		CONFIG_SHARP_16x9
1372
1373			Sharp 320x240. Active, color, single scan.
1374			It isn't 16x9, and I am not sure what it is.
1375
1376		CONFIG_SHARP_LQ64D341
1377
1378			Sharp LQ64D341 display, 640x480.
1379			Active, color, single scan.
1380
1381		CONFIG_HLD1045
1382
1383			HLD1045 display, 640x480.
1384			Active, color, single scan.
1385
1386		CONFIG_OPTREX_BW
1387
1388			Optrex	 CBL50840-2 NF-FW 99 22 M5
1389			or
1390			Hitachi	 LMG6912RPFC-00T
1391			or
1392			Hitachi	 SP14Q002
1393
1394			320x240. Black & white.
1395
1396		Normally display is black on white background; define
1397		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1398
1399- Splash Screen Support: CONFIG_SPLASH_SCREEN
1400
1401		If this option is set, the environment is checked for
1402		a variable "splashimage". If found, the usual display
1403		of logo, copyright and system information on the LCD
1404		is suppressed and the BMP image at the address
1405		specified in "splashimage" is loaded instead. The
1406		console is redirected to the "nulldev", too. This
1407		allows for a "silent" boot where a splash screen is
1408		loaded very quickly after power-on.
1409
1410		CONFIG_SPLASH_SCREEN_ALIGN
1411
1412		If this option is set the splash image can be freely positioned
1413		on the screen. Environment variable "splashpos" specifies the
1414		position as "x,y". If a positive number is given it is used as
1415		number of pixel from left/top. If a negative number is given it
1416		is used as number of pixel from right/bottom. You can also
1417		specify 'm' for centering the image.
1418
1419		Example:
1420		setenv splashpos m,m
1421			=> image at center of screen
1422
1423		setenv splashpos 30,20
1424			=> image at x = 30 and y = 20
1425
1426		setenv splashpos -10,m
1427			=> vertically centered image
1428			   at x = dspWidth - bmpWidth - 9
1429
1430- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1431
1432		If this option is set, additionally to standard BMP
1433		images, gzipped BMP images can be displayed via the
1434		splashscreen support or the bmp command.
1435
1436- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1437
1438		If this option is set, 8-bit RLE compressed BMP images
1439		can be displayed via the splashscreen support or the
1440		bmp command.
1441
1442- Compression support:
1443		CONFIG_BZIP2
1444
1445		If this option is set, support for bzip2 compressed
1446		images is included. If not, only uncompressed and gzip
1447		compressed images are supported.
1448
1449		NOTE: the bzip2 algorithm requires a lot of RAM, so
1450		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1451		be at least 4MB.
1452
1453		CONFIG_LZMA
1454
1455		If this option is set, support for lzma compressed
1456		images is included.
1457
1458		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1459		requires an amount of dynamic memory that is given by the
1460		formula:
1461
1462			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1463
1464		Where lc and lp stand for, respectively, Literal context bits
1465		and Literal pos bits.
1466
1467		This value is upper-bounded by 14MB in the worst case. Anyway,
1468		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1469		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1470		a very small buffer.
1471
1472		Use the lzmainfo tool to determinate the lc and lp values and
1473		then calculate the amount of needed dynamic memory (ensuring
1474		the appropriate CONFIG_SYS_MALLOC_LEN value).
1475
1476- MII/PHY support:
1477		CONFIG_PHY_ADDR
1478
1479		The address of PHY on MII bus.
1480
1481		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1482
1483		The clock frequency of the MII bus
1484
1485		CONFIG_PHY_GIGE
1486
1487		If this option is set, support for speed/duplex
1488		detection of gigabit PHY is included.
1489
1490		CONFIG_PHY_RESET_DELAY
1491
1492		Some PHY like Intel LXT971A need extra delay after
1493		reset before any MII register access is possible.
1494		For such PHY, set this option to the usec delay
1495		required. (minimum 300usec for LXT971A)
1496
1497		CONFIG_PHY_CMD_DELAY (ppc4xx)
1498
1499		Some PHY like Intel LXT971A need extra delay after
1500		command issued before MII status register can be read
1501
1502- Ethernet address:
1503		CONFIG_ETHADDR
1504		CONFIG_ETH1ADDR
1505		CONFIG_ETH2ADDR
1506		CONFIG_ETH3ADDR
1507		CONFIG_ETH4ADDR
1508		CONFIG_ETH5ADDR
1509
1510		Define a default value for Ethernet address to use
1511		for the respective Ethernet interface, in case this
1512		is not determined automatically.
1513
1514- IP address:
1515		CONFIG_IPADDR
1516
1517		Define a default value for the IP address to use for
1518		the default Ethernet interface, in case this is not
1519		determined through e.g. bootp.
1520		(Environment variable "ipaddr")
1521
1522- Server IP address:
1523		CONFIG_SERVERIP
1524
1525		Defines a default value for the IP address of a TFTP
1526		server to contact when using the "tftboot" command.
1527		(Environment variable "serverip")
1528
1529		CONFIG_KEEP_SERVERADDR
1530
1531		Keeps the server's MAC address, in the env 'serveraddr'
1532		for passing to bootargs (like Linux's netconsole option)
1533
1534- Gateway IP address:
1535		CONFIG_GATEWAYIP
1536
1537		Defines a default value for the IP address of the
1538		default router where packets to other networks are
1539		sent to.
1540		(Environment variable "gatewayip")
1541
1542- Subnet mask:
1543		CONFIG_NETMASK
1544
1545		Defines a default value for the subnet mask (or
1546		routing prefix) which is used to determine if an IP
1547		address belongs to the local subnet or needs to be
1548		forwarded through a router.
1549		(Environment variable "netmask")
1550
1551- Multicast TFTP Mode:
1552		CONFIG_MCAST_TFTP
1553
1554		Defines whether you want to support multicast TFTP as per
1555		rfc-2090; for example to work with atftp.  Lets lots of targets
1556		tftp down the same boot image concurrently.  Note: the Ethernet
1557		driver in use must provide a function: mcast() to join/leave a
1558		multicast group.
1559
1560- BOOTP Recovery Mode:
1561		CONFIG_BOOTP_RANDOM_DELAY
1562
1563		If you have many targets in a network that try to
1564		boot using BOOTP, you may want to avoid that all
1565		systems send out BOOTP requests at precisely the same
1566		moment (which would happen for instance at recovery
1567		from a power failure, when all systems will try to
1568		boot, thus flooding the BOOTP server. Defining
1569		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1570		inserted before sending out BOOTP requests. The
1571		following delays are inserted then:
1572
1573		1st BOOTP request:	delay 0 ... 1 sec
1574		2nd BOOTP request:	delay 0 ... 2 sec
1575		3rd BOOTP request:	delay 0 ... 4 sec
1576		4th and following
1577		BOOTP requests:		delay 0 ... 8 sec
1578
1579- DHCP Advanced Options:
1580		You can fine tune the DHCP functionality by defining
1581		CONFIG_BOOTP_* symbols:
1582
1583		CONFIG_BOOTP_SUBNETMASK
1584		CONFIG_BOOTP_GATEWAY
1585		CONFIG_BOOTP_HOSTNAME
1586		CONFIG_BOOTP_NISDOMAIN
1587		CONFIG_BOOTP_BOOTPATH
1588		CONFIG_BOOTP_BOOTFILESIZE
1589		CONFIG_BOOTP_DNS
1590		CONFIG_BOOTP_DNS2
1591		CONFIG_BOOTP_SEND_HOSTNAME
1592		CONFIG_BOOTP_NTPSERVER
1593		CONFIG_BOOTP_TIMEOFFSET
1594		CONFIG_BOOTP_VENDOREX
1595
1596		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1597		environment variable, not the BOOTP server.
1598
1599		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1600		serverip from a DHCP server, it is possible that more
1601		than one DNS serverip is offered to the client.
1602		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1603		serverip will be stored in the additional environment
1604		variable "dnsip2". The first DNS serverip is always
1605		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1606		is defined.
1607
1608		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1609		to do a dynamic update of a DNS server. To do this, they
1610		need the hostname of the DHCP requester.
1611		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1612		of the "hostname" environment variable is passed as
1613		option 12 to the DHCP server.
1614
1615		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1616
1617		A 32bit value in microseconds for a delay between
1618		receiving a "DHCP Offer" and sending the "DHCP Request".
1619		This fixes a problem with certain DHCP servers that don't
1620		respond 100% of the time to a "DHCP request". E.g. On an
1621		AT91RM9200 processor running at 180MHz, this delay needed
1622		to be *at least* 15,000 usec before a Windows Server 2003
1623		DHCP server would reply 100% of the time. I recommend at
1624		least 50,000 usec to be safe. The alternative is to hope
1625		that one of the retries will be successful but note that
1626		the DHCP timeout and retry process takes a longer than
1627		this delay.
1628
1629 - CDP Options:
1630		CONFIG_CDP_DEVICE_ID
1631
1632		The device id used in CDP trigger frames.
1633
1634		CONFIG_CDP_DEVICE_ID_PREFIX
1635
1636		A two character string which is prefixed to the MAC address
1637		of the device.
1638
1639		CONFIG_CDP_PORT_ID
1640
1641		A printf format string which contains the ascii name of
1642		the port. Normally is set to "eth%d" which sets
1643		eth0 for the first Ethernet, eth1 for the second etc.
1644
1645		CONFIG_CDP_CAPABILITIES
1646
1647		A 32bit integer which indicates the device capabilities;
1648		0x00000010 for a normal host which does not forwards.
1649
1650		CONFIG_CDP_VERSION
1651
1652		An ascii string containing the version of the software.
1653
1654		CONFIG_CDP_PLATFORM
1655
1656		An ascii string containing the name of the platform.
1657
1658		CONFIG_CDP_TRIGGER
1659
1660		A 32bit integer sent on the trigger.
1661
1662		CONFIG_CDP_POWER_CONSUMPTION
1663
1664		A 16bit integer containing the power consumption of the
1665		device in .1 of milliwatts.
1666
1667		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1668
1669		A byte containing the id of the VLAN.
1670
1671- Status LED:	CONFIG_STATUS_LED
1672
1673		Several configurations allow to display the current
1674		status using a LED. For instance, the LED will blink
1675		fast while running U-Boot code, stop blinking as
1676		soon as a reply to a BOOTP request was received, and
1677		start blinking slow once the Linux kernel is running
1678		(supported by a status LED driver in the Linux
1679		kernel). Defining CONFIG_STATUS_LED enables this
1680		feature in U-Boot.
1681
1682- CAN Support:	CONFIG_CAN_DRIVER
1683
1684		Defining CONFIG_CAN_DRIVER enables CAN driver support
1685		on those systems that support this (optional)
1686		feature, like the TQM8xxL modules.
1687
1688- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1689
1690		These enable I2C serial bus commands. Defining either of
1691		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1692		include the appropriate I2C driver for the selected CPU.
1693
1694		This will allow you to use i2c commands at the u-boot
1695		command line (as long as you set CONFIG_CMD_I2C in
1696		CONFIG_COMMANDS) and communicate with i2c based realtime
1697		clock chips. See common/cmd_i2c.c for a description of the
1698		command line interface.
1699
1700		CONFIG_HARD_I2C selects a hardware I2C controller.
1701
1702		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1703		bit-banging) driver instead of CPM or similar hardware
1704		support for I2C.
1705
1706		There are several other quantities that must also be
1707		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1708
1709		In both cases you will need to define CONFIG_SYS_I2C_SPEED
1710		to be the frequency (in Hz) at which you wish your i2c bus
1711		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
1712		the CPU's i2c node address).
1713
1714		Now, the u-boot i2c code for the mpc8xx
1715		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
1716		and so its address should therefore be cleared to 0 (See,
1717		eg, MPC823e User's Manual p.16-473). So, set
1718		CONFIG_SYS_I2C_SLAVE to 0.
1719
1720		CONFIG_SYS_I2C_INIT_MPC5XXX
1721
1722		When a board is reset during an i2c bus transfer
1723		chips might think that the current transfer is still
1724		in progress.  Reset the slave devices by sending start
1725		commands until the slave device responds.
1726
1727		That's all that's required for CONFIG_HARD_I2C.
1728
1729		If you use the software i2c interface (CONFIG_SOFT_I2C)
1730		then the following macros need to be defined (examples are
1731		from include/configs/lwmon.h):
1732
1733		I2C_INIT
1734
1735		(Optional). Any commands necessary to enable the I2C
1736		controller or configure ports.
1737
1738		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
1739
1740		I2C_PORT
1741
1742		(Only for MPC8260 CPU). The I/O port to use (the code
1743		assumes both bits are on the same port). Valid values
1744		are 0..3 for ports A..D.
1745
1746		I2C_ACTIVE
1747
1748		The code necessary to make the I2C data line active
1749		(driven).  If the data line is open collector, this
1750		define can be null.
1751
1752		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1753
1754		I2C_TRISTATE
1755
1756		The code necessary to make the I2C data line tri-stated
1757		(inactive).  If the data line is open collector, this
1758		define can be null.
1759
1760		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1761
1762		I2C_READ
1763
1764		Code that returns TRUE if the I2C data line is high,
1765		FALSE if it is low.
1766
1767		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1768
1769		I2C_SDA(bit)
1770
1771		If <bit> is TRUE, sets the I2C data line high. If it
1772		is FALSE, it clears it (low).
1773
1774		eg: #define I2C_SDA(bit) \
1775			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1776			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
1777
1778		I2C_SCL(bit)
1779
1780		If <bit> is TRUE, sets the I2C clock line high. If it
1781		is FALSE, it clears it (low).
1782
1783		eg: #define I2C_SCL(bit) \
1784			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1785			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
1786
1787		I2C_DELAY
1788
1789		This delay is invoked four times per clock cycle so this
1790		controls the rate of data transfer.  The data rate thus
1791		is 1 / (I2C_DELAY * 4). Often defined to be something
1792		like:
1793
1794		#define I2C_DELAY  udelay(2)
1795
1796		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1797
1798		If your arch supports the generic GPIO framework (asm/gpio.h),
1799		then you may alternatively define the two GPIOs that are to be
1800		used as SCL / SDA.  Any of the previous I2C_xxx macros will
1801		have GPIO-based defaults assigned to them as appropriate.
1802
1803		You should define these to the GPIO value as given directly to
1804		the generic GPIO functions.
1805
1806		CONFIG_SYS_I2C_INIT_BOARD
1807
1808		When a board is reset during an i2c bus transfer
1809		chips might think that the current transfer is still
1810		in progress. On some boards it is possible to access
1811		the i2c SCLK line directly, either by using the
1812		processor pin as a GPIO or by having a second pin
1813		connected to the bus. If this option is defined a
1814		custom i2c_init_board() routine in boards/xxx/board.c
1815		is run early in the boot sequence.
1816
1817		CONFIG_SYS_I2C_BOARD_LATE_INIT
1818
1819		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
1820		defined a custom i2c_board_late_init() routine in
1821		boards/xxx/board.c is run AFTER the operations in i2c_init()
1822		is completed. This callpoint can be used to unreset i2c bus
1823		using CPU i2c controller register accesses for CPUs whose i2c
1824		controller provide such a method. It is called at the end of
1825		i2c_init() to allow i2c_init operations to setup the i2c bus
1826		controller on the CPU (e.g. setting bus speed & slave address).
1827
1828		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1829
1830		This option enables configuration of bi_iic_fast[] flags
1831		in u-boot bd_info structure based on u-boot environment
1832		variable "i2cfast". (see also i2cfast)
1833
1834		CONFIG_I2C_MULTI_BUS
1835
1836		This option allows the use of multiple I2C buses, each of which
1837		must have a controller.	 At any point in time, only one bus is
1838		active.	 To switch to a different bus, use the 'i2c dev' command.
1839		Note that bus numbering is zero-based.
1840
1841		CONFIG_SYS_I2C_NOPROBES
1842
1843		This option specifies a list of I2C devices that will be skipped
1844		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
1845		is set, specify a list of bus-device pairs.  Otherwise, specify
1846		a 1D array of device addresses
1847
1848		e.g.
1849			#undef	CONFIG_I2C_MULTI_BUS
1850			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1851
1852		will skip addresses 0x50 and 0x68 on a board with one I2C bus
1853
1854			#define CONFIG_I2C_MULTI_BUS
1855			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
1856
1857		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1858
1859		CONFIG_SYS_SPD_BUS_NUM
1860
1861		If defined, then this indicates the I2C bus number for DDR SPD.
1862		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1863
1864		CONFIG_SYS_RTC_BUS_NUM
1865
1866		If defined, then this indicates the I2C bus number for the RTC.
1867		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1868
1869		CONFIG_SYS_DTT_BUS_NUM
1870
1871		If defined, then this indicates the I2C bus number for the DTT.
1872		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
1873
1874		CONFIG_SYS_I2C_DTT_ADDR:
1875
1876		If defined, specifies the I2C address of the DTT device.
1877		If not defined, then U-Boot uses predefined value for
1878		specified DTT device.
1879
1880		CONFIG_FSL_I2C
1881
1882		Define this option if you want to use Freescale's I2C driver in
1883		drivers/i2c/fsl_i2c.c.
1884
1885		CONFIG_I2C_MUX
1886
1887		Define this option if you have I2C devices reached over 1 .. n
1888		I2C Muxes like the pca9544a. This option addes a new I2C
1889		Command "i2c bus [muxtype:muxaddr:muxchannel]" which adds a
1890		new I2C Bus to the existing I2C Busses. If you select the
1891		new Bus with "i2c dev", u-bbot sends first the commandos for
1892		the muxes to activate this new "bus".
1893
1894		CONFIG_I2C_MULTI_BUS must be also defined, to use this
1895		feature!
1896
1897		Example:
1898		Adding a new I2C Bus reached over 2 pca9544a muxes
1899			The First mux with address 70 and channel 6
1900			The Second mux with address 71 and channel 4
1901
1902		=> i2c bus pca9544a:70:6:pca9544a:71:4
1903
1904		Use the "i2c bus" command without parameter, to get a list
1905		of I2C Busses with muxes:
1906
1907		=> i2c bus
1908		Busses reached over muxes:
1909		Bus ID: 2
1910		  reached over Mux(es):
1911		    pca9544a@70 ch: 4
1912		Bus ID: 3
1913		  reached over Mux(es):
1914		    pca9544a@70 ch: 6
1915		    pca9544a@71 ch: 4
1916		=>
1917
1918		If you now switch to the new I2C Bus 3 with "i2c dev 3"
1919		u-boot first sends the command to the mux@70 to enable
1920		channel 6, and then the command to the mux@71 to enable
1921		the channel 4.
1922
1923		After that, you can use the "normal" i2c commands as
1924		usual to communicate with your I2C devices behind
1925		the 2 muxes.
1926
1927		This option is actually implemented for the bitbanging
1928		algorithm in common/soft_i2c.c and for the Hardware I2C
1929		Bus on the MPC8260. But it should be not so difficult
1930		to add this option to other architectures.
1931
1932		CONFIG_SOFT_I2C_READ_REPEATED_START
1933
1934		defining this will force the i2c_read() function in
1935		the soft_i2c driver to perform an I2C repeated start
1936		between writing the address pointer and reading the
1937		data.  If this define is omitted the default behaviour
1938		of doing a stop-start sequence will be used.  Most I2C
1939		devices can use either method, but some require one or
1940		the other.
1941
1942- SPI Support:	CONFIG_SPI
1943
1944		Enables SPI driver (so far only tested with
1945		SPI EEPROM, also an instance works with Crystal A/D and
1946		D/As on the SACSng board)
1947
1948		CONFIG_SH_SPI
1949
1950		Enables the driver for SPI controller on SuperH. Currently
1951		only SH7757 is supported.
1952
1953		CONFIG_SPI_X
1954
1955		Enables extended (16-bit) SPI EEPROM addressing.
1956		(symmetrical to CONFIG_I2C_X)
1957
1958		CONFIG_SOFT_SPI
1959
1960		Enables a software (bit-bang) SPI driver rather than
1961		using hardware support. This is a general purpose
1962		driver that only requires three general I/O port pins
1963		(two outputs, one input) to function. If this is
1964		defined, the board configuration must define several
1965		SPI configuration items (port pins to use, etc). For
1966		an example, see include/configs/sacsng.h.
1967
1968		CONFIG_HARD_SPI
1969
1970		Enables a hardware SPI driver for general-purpose reads
1971		and writes.  As with CONFIG_SOFT_SPI, the board configuration
1972		must define a list of chip-select function pointers.
1973		Currently supported on some MPC8xxx processors.	 For an
1974		example, see include/configs/mpc8349emds.h.
1975
1976		CONFIG_MXC_SPI
1977
1978		Enables the driver for the SPI controllers on i.MX and MXC
1979		SoCs. Currently i.MX31/35/51 are supported.
1980
1981- FPGA Support: CONFIG_FPGA
1982
1983		Enables FPGA subsystem.
1984
1985		CONFIG_FPGA_<vendor>
1986
1987		Enables support for specific chip vendors.
1988		(ALTERA, XILINX)
1989
1990		CONFIG_FPGA_<family>
1991
1992		Enables support for FPGA family.
1993		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1994
1995		CONFIG_FPGA_COUNT
1996
1997		Specify the number of FPGA devices to support.
1998
1999		CONFIG_SYS_FPGA_PROG_FEEDBACK
2000
2001		Enable printing of hash marks during FPGA configuration.
2002
2003		CONFIG_SYS_FPGA_CHECK_BUSY
2004
2005		Enable checks on FPGA configuration interface busy
2006		status by the configuration function. This option
2007		will require a board or device specific function to
2008		be written.
2009
2010		CONFIG_FPGA_DELAY
2011
2012		If defined, a function that provides delays in the FPGA
2013		configuration driver.
2014
2015		CONFIG_SYS_FPGA_CHECK_CTRLC
2016		Allow Control-C to interrupt FPGA configuration
2017
2018		CONFIG_SYS_FPGA_CHECK_ERROR
2019
2020		Check for configuration errors during FPGA bitfile
2021		loading. For example, abort during Virtex II
2022		configuration if the INIT_B line goes low (which
2023		indicated a CRC error).
2024
2025		CONFIG_SYS_FPGA_WAIT_INIT
2026
2027		Maximum time to wait for the INIT_B line to deassert
2028		after PROB_B has been deasserted during a Virtex II
2029		FPGA configuration sequence. The default time is 500
2030		ms.
2031
2032		CONFIG_SYS_FPGA_WAIT_BUSY
2033
2034		Maximum time to wait for BUSY to deassert during
2035		Virtex II FPGA configuration. The default is 5 ms.
2036
2037		CONFIG_SYS_FPGA_WAIT_CONFIG
2038
2039		Time to wait after FPGA configuration. The default is
2040		200 ms.
2041
2042- Configuration Management:
2043		CONFIG_IDENT_STRING
2044
2045		If defined, this string will be added to the U-Boot
2046		version information (U_BOOT_VERSION)
2047
2048- Vendor Parameter Protection:
2049
2050		U-Boot considers the values of the environment
2051		variables "serial#" (Board Serial Number) and
2052		"ethaddr" (Ethernet Address) to be parameters that
2053		are set once by the board vendor / manufacturer, and
2054		protects these variables from casual modification by
2055		the user. Once set, these variables are read-only,
2056		and write or delete attempts are rejected. You can
2057		change this behaviour:
2058
2059		If CONFIG_ENV_OVERWRITE is #defined in your config
2060		file, the write protection for vendor parameters is
2061		completely disabled. Anybody can change or delete
2062		these parameters.
2063
2064		Alternatively, if you #define _both_ CONFIG_ETHADDR
2065		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2066		Ethernet address is installed in the environment,
2067		which can be changed exactly ONCE by the user. [The
2068		serial# is unaffected by this, i. e. it remains
2069		read-only.]
2070
2071- Protected RAM:
2072		CONFIG_PRAM
2073
2074		Define this variable to enable the reservation of
2075		"protected RAM", i. e. RAM which is not overwritten
2076		by U-Boot. Define CONFIG_PRAM to hold the number of
2077		kB you want to reserve for pRAM. You can overwrite
2078		this default value by defining an environment
2079		variable "pram" to the number of kB you want to
2080		reserve. Note that the board info structure will
2081		still show the full amount of RAM. If pRAM is
2082		reserved, a new environment variable "mem" will
2083		automatically be defined to hold the amount of
2084		remaining RAM in a form that can be passed as boot
2085		argument to Linux, for instance like that:
2086
2087			setenv bootargs ... mem=\${mem}
2088			saveenv
2089
2090		This way you can tell Linux not to use this memory,
2091		either, which results in a memory region that will
2092		not be affected by reboots.
2093
2094		*WARNING* If your board configuration uses automatic
2095		detection of the RAM size, you must make sure that
2096		this memory test is non-destructive. So far, the
2097		following board configurations are known to be
2098		"pRAM-clean":
2099
2100			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
2101			HERMES, IP860, RPXlite, LWMON, LANTEC,
2102			FLAGADM, TQM8260
2103
2104- Error Recovery:
2105		CONFIG_PANIC_HANG
2106
2107		Define this variable to stop the system in case of a
2108		fatal error, so that you have to reset it manually.
2109		This is probably NOT a good idea for an embedded
2110		system where you want the system to reboot
2111		automatically as fast as possible, but it may be
2112		useful during development since you can try to debug
2113		the conditions that lead to the situation.
2114
2115		CONFIG_NET_RETRY_COUNT
2116
2117		This variable defines the number of retries for
2118		network operations like ARP, RARP, TFTP, or BOOTP
2119		before giving up the operation. If not defined, a
2120		default value of 5 is used.
2121
2122		CONFIG_ARP_TIMEOUT
2123
2124		Timeout waiting for an ARP reply in milliseconds.
2125
2126- Command Interpreter:
2127		CONFIG_AUTO_COMPLETE
2128
2129		Enable auto completion of commands using TAB.
2130
2131		Note that this feature has NOT been implemented yet
2132		for the "hush" shell.
2133
2134
2135		CONFIG_SYS_HUSH_PARSER
2136
2137		Define this variable to enable the "hush" shell (from
2138		Busybox) as command line interpreter, thus enabling
2139		powerful command line syntax like
2140		if...then...else...fi conditionals or `&&' and '||'
2141		constructs ("shell scripts").
2142
2143		If undefined, you get the old, much simpler behaviour
2144		with a somewhat smaller memory footprint.
2145
2146
2147		CONFIG_SYS_PROMPT_HUSH_PS2
2148
2149		This defines the secondary prompt string, which is
2150		printed when the command interpreter needs more input
2151		to complete a command. Usually "> ".
2152
2153	Note:
2154
2155		In the current implementation, the local variables
2156		space and global environment variables space are
2157		separated. Local variables are those you define by
2158		simply typing `name=value'. To access a local
2159		variable later on, you have write `$name' or
2160		`${name}'; to execute the contents of a variable
2161		directly type `$name' at the command prompt.
2162
2163		Global environment variables are those you use
2164		setenv/printenv to work with. To run a command stored
2165		in such a variable, you need to use the run command,
2166		and you must not use the '$' sign to access them.
2167
2168		To store commands and special characters in a
2169		variable, please use double quotation marks
2170		surrounding the whole text of the variable, instead
2171		of the backslashes before semicolons and special
2172		symbols.
2173
2174- Commandline Editing and History:
2175		CONFIG_CMDLINE_EDITING
2176
2177		Enable editing and History functions for interactive
2178		commandline input operations
2179
2180- Default Environment:
2181		CONFIG_EXTRA_ENV_SETTINGS
2182
2183		Define this to contain any number of null terminated
2184		strings (variable = value pairs) that will be part of
2185		the default environment compiled into the boot image.
2186
2187		For example, place something like this in your
2188		board's config file:
2189
2190		#define CONFIG_EXTRA_ENV_SETTINGS \
2191			"myvar1=value1\0" \
2192			"myvar2=value2\0"
2193
2194		Warning: This method is based on knowledge about the
2195		internal format how the environment is stored by the
2196		U-Boot code. This is NOT an official, exported
2197		interface! Although it is unlikely that this format
2198		will change soon, there is no guarantee either.
2199		You better know what you are doing here.
2200
2201		Note: overly (ab)use of the default environment is
2202		discouraged. Make sure to check other ways to preset
2203		the environment like the "source" command or the
2204		boot command first.
2205
2206- DataFlash Support:
2207		CONFIG_HAS_DATAFLASH
2208
2209		Defining this option enables DataFlash features and
2210		allows to read/write in Dataflash via the standard
2211		commands cp, md...
2212
2213- Serial Flash support
2214		CONFIG_CMD_SF
2215
2216		Defining this option enables SPI flash commands
2217		'sf probe/read/write/erase/update'.
2218
2219		Usage requires an initial 'probe' to define the serial
2220		flash parameters, followed by read/write/erase/update
2221		commands.
2222
2223		The following defaults may be provided by the platform
2224		to handle the common case when only a single serial
2225		flash is present on the system.
2226
2227		CONFIG_SF_DEFAULT_BUS		Bus identifier
2228		CONFIG_SF_DEFAULT_CS		Chip-select
2229		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2230		CONFIG_SF_DEFAULT_SPEED		in Hz
2231
2232- SystemACE Support:
2233		CONFIG_SYSTEMACE
2234
2235		Adding this option adds support for Xilinx SystemACE
2236		chips attached via some sort of local bus. The address
2237		of the chip must also be defined in the
2238		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2239
2240		#define CONFIG_SYSTEMACE
2241		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2242
2243		When SystemACE support is added, the "ace" device type
2244		becomes available to the fat commands, i.e. fatls.
2245
2246- TFTP Fixed UDP Port:
2247		CONFIG_TFTP_PORT
2248
2249		If this is defined, the environment variable tftpsrcp
2250		is used to supply the TFTP UDP source port value.
2251		If tftpsrcp isn't defined, the normal pseudo-random port
2252		number generator is used.
2253
2254		Also, the environment variable tftpdstp is used to supply
2255		the TFTP UDP destination port value.  If tftpdstp isn't
2256		defined, the normal port 69 is used.
2257
2258		The purpose for tftpsrcp is to allow a TFTP server to
2259		blindly start the TFTP transfer using the pre-configured
2260		target IP address and UDP port. This has the effect of
2261		"punching through" the (Windows XP) firewall, allowing
2262		the remainder of the TFTP transfer to proceed normally.
2263		A better solution is to properly configure the firewall,
2264		but sometimes that is not allowed.
2265
2266- Show boot progress:
2267		CONFIG_SHOW_BOOT_PROGRESS
2268
2269		Defining this option allows to add some board-
2270		specific code (calling a user-provided function
2271		"show_boot_progress(int)") that enables you to show
2272		the system's boot progress on some display (for
2273		example, some LED's) on your board. At the moment,
2274		the following checkpoints are implemented:
2275
2276- Detailed boot stage timing
2277		CONFIG_BOOTSTAGE
2278		Define this option to get detailed timing of each stage
2279		of the boot process.
2280
2281		CONFIG_BOOTSTAGE_USER_COUNT
2282		This is the number of available user bootstage records.
2283		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
2284		a new ID will be allocated from this stash. If you exceed
2285		the limit, recording will stop.
2286
2287		CONFIG_BOOTSTAGE_REPORT
2288		Define this to print a report before boot, similar to this:
2289
2290		Timer summary in microseconds:
2291		       Mark    Elapsed  Stage
2292			  0          0  reset
2293		  3,575,678  3,575,678  board_init_f start
2294		  3,575,695         17  arch_cpu_init A9
2295		  3,575,777         82  arch_cpu_init done
2296		  3,659,598     83,821  board_init_r start
2297		  3,910,375    250,777  main_loop
2298		 29,916,167 26,005,792  bootm_start
2299		 30,361,327    445,160  start_kernel
2300
2301Legacy uImage format:
2302
2303  Arg	Where			When
2304    1	common/cmd_bootm.c	before attempting to boot an image
2305   -1	common/cmd_bootm.c	Image header has bad	 magic number
2306    2	common/cmd_bootm.c	Image header has correct magic number
2307   -2	common/cmd_bootm.c	Image header has bad	 checksum
2308    3	common/cmd_bootm.c	Image header has correct checksum
2309   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2310    4	common/cmd_bootm.c	Image data   has correct checksum
2311   -4	common/cmd_bootm.c	Image is for unsupported architecture
2312    5	common/cmd_bootm.c	Architecture check OK
2313   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2314    6	common/cmd_bootm.c	Image Type check OK
2315   -6	common/cmd_bootm.c	gunzip uncompression error
2316   -7	common/cmd_bootm.c	Unimplemented compression type
2317    7	common/cmd_bootm.c	Uncompression OK
2318    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2319   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2320
2321    9	common/image.c		Start initial ramdisk verification
2322  -10	common/image.c		Ramdisk header has bad	   magic number
2323  -11	common/image.c		Ramdisk header has bad	   checksum
2324   10	common/image.c		Ramdisk header is OK
2325  -12	common/image.c		Ramdisk data   has bad	   checksum
2326   11	common/image.c		Ramdisk data   has correct checksum
2327   12	common/image.c		Ramdisk verification complete, start loading
2328  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2329   13	common/image.c		Start multifile image verification
2330   14	common/image.c		No initial ramdisk, no multifile, continue.
2331
2332   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2333
2334  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2335  -31	post/post.c		POST test failed, detected by post_output_backlog()
2336  -32	post/post.c		POST test failed, detected by post_run_single()
2337
2338   34	common/cmd_doc.c	before loading a Image from a DOC device
2339  -35	common/cmd_doc.c	Bad usage of "doc" command
2340   35	common/cmd_doc.c	correct usage of "doc" command
2341  -36	common/cmd_doc.c	No boot device
2342   36	common/cmd_doc.c	correct boot device
2343  -37	common/cmd_doc.c	Unknown Chip ID on boot device
2344   37	common/cmd_doc.c	correct chip ID found, device available
2345  -38	common/cmd_doc.c	Read Error on boot device
2346   38	common/cmd_doc.c	reading Image header from DOC device OK
2347  -39	common/cmd_doc.c	Image header has bad magic number
2348   39	common/cmd_doc.c	Image header has correct magic number
2349  -40	common/cmd_doc.c	Error reading Image from DOC device
2350   40	common/cmd_doc.c	Image header has correct magic number
2351   41	common/cmd_ide.c	before loading a Image from a IDE device
2352  -42	common/cmd_ide.c	Bad usage of "ide" command
2353   42	common/cmd_ide.c	correct usage of "ide" command
2354  -43	common/cmd_ide.c	No boot device
2355   43	common/cmd_ide.c	boot device found
2356  -44	common/cmd_ide.c	Device not available
2357   44	common/cmd_ide.c	Device available
2358  -45	common/cmd_ide.c	wrong partition selected
2359   45	common/cmd_ide.c	partition selected
2360  -46	common/cmd_ide.c	Unknown partition table
2361   46	common/cmd_ide.c	valid partition table found
2362  -47	common/cmd_ide.c	Invalid partition type
2363   47	common/cmd_ide.c	correct partition type
2364  -48	common/cmd_ide.c	Error reading Image Header on boot device
2365   48	common/cmd_ide.c	reading Image Header from IDE device OK
2366  -49	common/cmd_ide.c	Image header has bad magic number
2367   49	common/cmd_ide.c	Image header has correct magic number
2368  -50	common/cmd_ide.c	Image header has bad	 checksum
2369   50	common/cmd_ide.c	Image header has correct checksum
2370  -51	common/cmd_ide.c	Error reading Image from IDE device
2371   51	common/cmd_ide.c	reading Image from IDE device OK
2372   52	common/cmd_nand.c	before loading a Image from a NAND device
2373  -53	common/cmd_nand.c	Bad usage of "nand" command
2374   53	common/cmd_nand.c	correct usage of "nand" command
2375  -54	common/cmd_nand.c	No boot device
2376   54	common/cmd_nand.c	boot device found
2377  -55	common/cmd_nand.c	Unknown Chip ID on boot device
2378   55	common/cmd_nand.c	correct chip ID found, device available
2379  -56	common/cmd_nand.c	Error reading Image Header on boot device
2380   56	common/cmd_nand.c	reading Image Header from NAND device OK
2381  -57	common/cmd_nand.c	Image header has bad magic number
2382   57	common/cmd_nand.c	Image header has correct magic number
2383  -58	common/cmd_nand.c	Error reading Image from NAND device
2384   58	common/cmd_nand.c	reading Image from NAND device OK
2385
2386  -60	common/env_common.c	Environment has a bad CRC, using default
2387
2388   64	net/eth.c		starting with Ethernet configuration.
2389  -64	net/eth.c		no Ethernet found.
2390   65	net/eth.c		Ethernet found.
2391
2392  -80	common/cmd_net.c	usage wrong
2393   80	common/cmd_net.c	before calling NetLoop()
2394  -81	common/cmd_net.c	some error in NetLoop() occurred
2395   81	common/cmd_net.c	NetLoop() back without error
2396  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
2397   82	common/cmd_net.c	trying automatic boot
2398   83	common/cmd_net.c	running "source" command
2399  -83	common/cmd_net.c	some error in automatic boot or "source" command
2400   84	common/cmd_net.c	end without errors
2401
2402FIT uImage format:
2403
2404  Arg	Where			When
2405  100	common/cmd_bootm.c	Kernel FIT Image has correct format
2406 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
2407  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
2408 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
2409  102	common/cmd_bootm.c	Kernel unit name specified
2410 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
2411  103	common/cmd_bootm.c	Found configuration node
2412  104	common/cmd_bootm.c	Got kernel subimage node offset
2413 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
2414  105	common/cmd_bootm.c	Kernel subimage hash verification OK
2415 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
2416  106	common/cmd_bootm.c	Architecture check OK
2417 -106	common/cmd_bootm.c	Kernel subimage has wrong type
2418  107	common/cmd_bootm.c	Kernel subimage type OK
2419 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
2420  108	common/cmd_bootm.c	Got kernel subimage data/size
2421 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
2422 -109	common/cmd_bootm.c	Can't get kernel subimage type
2423 -110	common/cmd_bootm.c	Can't get kernel subimage comp
2424 -111	common/cmd_bootm.c	Can't get kernel subimage os
2425 -112	common/cmd_bootm.c	Can't get kernel subimage load address
2426 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
2427
2428  120	common/image.c		Start initial ramdisk verification
2429 -120	common/image.c		Ramdisk FIT image has incorrect format
2430  121	common/image.c		Ramdisk FIT image has correct format
2431  122	common/image.c		No ramdisk subimage unit name, using configuration
2432 -122	common/image.c		Can't get configuration for ramdisk subimage
2433  123	common/image.c		Ramdisk unit name specified
2434 -124	common/image.c		Can't get ramdisk subimage node offset
2435  125	common/image.c		Got ramdisk subimage node offset
2436 -125	common/image.c		Ramdisk subimage hash verification failed
2437  126	common/image.c		Ramdisk subimage hash verification OK
2438 -126	common/image.c		Ramdisk subimage for unsupported architecture
2439  127	common/image.c		Architecture check OK
2440 -127	common/image.c		Can't get ramdisk subimage data/size
2441  128	common/image.c		Got ramdisk subimage data/size
2442  129	common/image.c		Can't get ramdisk load address
2443 -129	common/image.c		Got ramdisk load address
2444
2445 -130	common/cmd_doc.c	Incorrect FIT image format
2446  131	common/cmd_doc.c	FIT image format OK
2447
2448 -140	common/cmd_ide.c	Incorrect FIT image format
2449  141	common/cmd_ide.c	FIT image format OK
2450
2451 -150	common/cmd_nand.c	Incorrect FIT image format
2452  151	common/cmd_nand.c	FIT image format OK
2453
2454- Standalone program support:
2455		CONFIG_STANDALONE_LOAD_ADDR
2456
2457		This option defines a board specific value for the
2458		address where standalone program gets loaded, thus
2459		overwriting the architecture dependent default
2460		settings.
2461
2462- Frame Buffer Address:
2463		CONFIG_FB_ADDR
2464
2465		Define CONFIG_FB_ADDR if you want to use specific
2466		address for frame buffer.
2467		Then system will reserve the frame buffer address to
2468		defined address instead of lcd_setmem (this function
2469		grabs the memory for frame buffer by panel's size).
2470
2471		Please see board_init_f function.
2472
2473- Automatic software updates via TFTP server
2474		CONFIG_UPDATE_TFTP
2475		CONFIG_UPDATE_TFTP_CNT_MAX
2476		CONFIG_UPDATE_TFTP_MSEC_MAX
2477
2478		These options enable and control the auto-update feature;
2479		for a more detailed description refer to doc/README.update.
2480
2481- MTD Support (mtdparts command, UBI support)
2482		CONFIG_MTD_DEVICE
2483
2484		Adds the MTD device infrastructure from the Linux kernel.
2485		Needed for mtdparts command support.
2486
2487		CONFIG_MTD_PARTITIONS
2488
2489		Adds the MTD partitioning infrastructure from the Linux
2490		kernel. Needed for UBI support.
2491
2492- SPL framework
2493		CONFIG_SPL
2494		Enable building of SPL globally.
2495
2496		CONFIG_SPL_LDSCRIPT
2497		LDSCRIPT for linking the SPL binary.
2498
2499		CONFIG_SPL_MAX_SIZE
2500		Maximum binary size (text, data and rodata) of the SPL binary.
2501
2502		CONFIG_SPL_TEXT_BASE
2503		TEXT_BASE for linking the SPL binary.
2504
2505		CONFIG_SPL_BSS_START_ADDR
2506		Link address for the BSS within the SPL binary.
2507
2508		CONFIG_SPL_BSS_MAX_SIZE
2509		Maximum binary size of the BSS section of the SPL binary.
2510
2511		CONFIG_SPL_STACK
2512		Adress of the start of the stack SPL will use
2513
2514		CONFIG_SYS_SPL_MALLOC_START
2515		Starting address of the malloc pool used in SPL.
2516
2517		CONFIG_SYS_SPL_MALLOC_SIZE
2518		The size of the malloc pool used in SPL.
2519
2520		CONFIG_SPL_LIBCOMMON_SUPPORT
2521		Support for common/libcommon.o in SPL binary
2522
2523		CONFIG_SPL_LIBDISK_SUPPORT
2524		Support for disk/libdisk.o in SPL binary
2525
2526		CONFIG_SPL_I2C_SUPPORT
2527		Support for drivers/i2c/libi2c.o in SPL binary
2528
2529		CONFIG_SPL_GPIO_SUPPORT
2530		Support for drivers/gpio/libgpio.o in SPL binary
2531
2532		CONFIG_SPL_MMC_SUPPORT
2533		Support for drivers/mmc/libmmc.o in SPL binary
2534
2535		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
2536		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
2537		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
2538		Address, size and partition on the MMC to load U-Boot from
2539		when the MMC is being used in raw mode.
2540
2541		CONFIG_SPL_FAT_SUPPORT
2542		Support for fs/fat/libfat.o in SPL binary
2543
2544		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
2545		Filename to read to load U-Boot when reading from FAT
2546
2547		CONFIG_SPL_NAND_SIMPLE
2548		Support for drivers/mtd/nand/libnand.o in SPL binary
2549
2550		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
2551		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
2552		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
2553		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
2554		CONFIG_SYS_NAND_ECCBYTES
2555		Defines the size and behavior of the NAND that SPL uses
2556		to read U-Boot with CONFIG_SPL_NAND_SIMPLE
2557
2558		CONFIG_SYS_NAND_U_BOOT_OFFS
2559		Location in NAND for CONFIG_SPL_NAND_SIMPLE to read U-Boot
2560		from.
2561
2562		CONFIG_SYS_NAND_U_BOOT_START
2563		Location in memory for CONFIG_SPL_NAND_SIMPLE to load U-Boot
2564		to.
2565
2566		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
2567		Define this if you need to first read the OOB and then the
2568		data. This is used for example on davinci plattforms.
2569
2570		CONFIG_SPL_OMAP3_ID_NAND
2571		Support for an OMAP3-specific set of functions to return the
2572		ID and MFR of the first attached NAND chip, if present.
2573
2574		CONFIG_SPL_SERIAL_SUPPORT
2575		Support for drivers/serial/libserial.o in SPL binary
2576
2577		CONFIG_SPL_SPI_FLASH_SUPPORT
2578		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
2579
2580		CONFIG_SPL_SPI_SUPPORT
2581		Support for drivers/spi/libspi.o in SPL binary
2582
2583		CONFIG_SPL_LIBGENERIC_SUPPORT
2584		Support for lib/libgeneric.o in SPL binary
2585
2586Modem Support:
2587--------------
2588
2589[so far only for SMDK2400 boards]
2590
2591- Modem support enable:
2592		CONFIG_MODEM_SUPPORT
2593
2594- RTS/CTS Flow control enable:
2595		CONFIG_HWFLOW
2596
2597- Modem debug support:
2598		CONFIG_MODEM_SUPPORT_DEBUG
2599
2600		Enables debugging stuff (char screen[1024], dbg())
2601		for modem support. Useful only with BDI2000.
2602
2603- Interrupt support (PPC):
2604
2605		There are common interrupt_init() and timer_interrupt()
2606		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2607		for CPU specific initialization. interrupt_init_cpu()
2608		should set decrementer_count to appropriate value. If
2609		CPU resets decrementer automatically after interrupt
2610		(ppc4xx) it should set decrementer_count to zero.
2611		timer_interrupt() calls timer_interrupt_cpu() for CPU
2612		specific handling. If board has watchdog / status_led
2613		/ other_activity_monitor it works automatically from
2614		general timer_interrupt().
2615
2616- General:
2617
2618		In the target system modem support is enabled when a
2619		specific key (key combination) is pressed during
2620		power-on. Otherwise U-Boot will boot normally
2621		(autoboot). The key_pressed() function is called from
2622		board_init(). Currently key_pressed() is a dummy
2623		function, returning 1 and thus enabling modem
2624		initialization.
2625
2626		If there are no modem init strings in the
2627		environment, U-Boot proceed to autoboot; the
2628		previous output (banner, info printfs) will be
2629		suppressed, though.
2630
2631		See also: doc/README.Modem
2632
2633Board initialization settings:
2634------------------------------
2635
2636During Initialization u-boot calls a number of board specific functions
2637to allow the preparation of board specific prerequisites, e.g. pin setup
2638before drivers are initialized. To enable these callbacks the
2639following configuration macros have to be defined. Currently this is
2640architecture specific, so please check arch/your_architecture/lib/board.c
2641typically in board_init_f() and board_init_r().
2642
2643- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2644- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2645- CONFIG_BOARD_LATE_INIT: Call board_late_init()
2646- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2647
2648Configuration Settings:
2649-----------------------
2650
2651- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2652		undefine this when you're short of memory.
2653
2654- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2655		width of the commands listed in the 'help' command output.
2656
2657- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
2658		prompt for user input.
2659
2660- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
2661
2662- CONFIG_SYS_PBSIZE:	Buffer size for Console output
2663
2664- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
2665
2666- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2667		the application (usually a Linux kernel) when it is
2668		booted
2669
2670- CONFIG_SYS_BAUDRATE_TABLE:
2671		List of legal baudrate settings for this board.
2672
2673- CONFIG_SYS_CONSOLE_INFO_QUIET
2674		Suppress display of console information at boot.
2675
2676- CONFIG_SYS_CONSOLE_IS_IN_ENV
2677		If the board specific function
2678			extern int overwrite_console (void);
2679		returns 1, the stdin, stderr and stdout are switched to the
2680		serial port, else the settings in the environment are used.
2681
2682- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
2683		Enable the call to overwrite_console().
2684
2685- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
2686		Enable overwrite of previous console environment settings.
2687
2688- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
2689		Begin and End addresses of the area used by the
2690		simple memory test.
2691
2692- CONFIG_SYS_ALT_MEMTEST:
2693		Enable an alternate, more extensive memory test.
2694
2695- CONFIG_SYS_MEMTEST_SCRATCH:
2696		Scratch address used by the alternate memory test
2697		You only need to set this if address zero isn't writeable
2698
2699- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
2700		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2701		this specified memory area will get subtracted from the top
2702		(end) of RAM and won't get "touched" at all by U-Boot. By
2703		fixing up gd->ram_size the Linux kernel should gets passed
2704		the now "corrected" memory size and won't touch it either.
2705		This should work for arch/ppc and arch/powerpc. Only Linux
2706		board ports in arch/powerpc with bootwrapper support that
2707		recalculate the memory size from the SDRAM controller setup
2708		will have to get fixed in Linux additionally.
2709
2710		This option can be used as a workaround for the 440EPx/GRx
2711		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2712		be touched.
2713
2714		WARNING: Please make sure that this value is a multiple of
2715		the Linux page size (normally 4k). If this is not the case,
2716		then the end address of the Linux memory will be located at a
2717		non page size aligned address and this could cause major
2718		problems.
2719
2720- CONFIG_SYS_TFTP_LOADADDR:
2721		Default load address for network file downloads
2722
2723- CONFIG_SYS_LOADS_BAUD_CHANGE:
2724		Enable temporary baudrate change while serial download
2725
2726- CONFIG_SYS_SDRAM_BASE:
2727		Physical start address of SDRAM. _Must_ be 0 here.
2728
2729- CONFIG_SYS_MBIO_BASE:
2730		Physical start address of Motherboard I/O (if using a
2731		Cogent motherboard)
2732
2733- CONFIG_SYS_FLASH_BASE:
2734		Physical start address of Flash memory.
2735
2736- CONFIG_SYS_MONITOR_BASE:
2737		Physical start address of boot monitor code (set by
2738		make config files to be same as the text base address
2739		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
2740		CONFIG_SYS_FLASH_BASE when booting from flash.
2741
2742- CONFIG_SYS_MONITOR_LEN:
2743		Size of memory reserved for monitor code, used to
2744		determine _at_compile_time_ (!) if the environment is
2745		embedded within the U-Boot image, or in a separate
2746		flash sector.
2747
2748- CONFIG_SYS_MALLOC_LEN:
2749		Size of DRAM reserved for malloc() use.
2750
2751- CONFIG_SYS_BOOTM_LEN:
2752		Normally compressed uImages are limited to an
2753		uncompressed size of 8 MBytes. If this is not enough,
2754		you can define CONFIG_SYS_BOOTM_LEN in your board config file
2755		to adjust this setting to your needs.
2756
2757- CONFIG_SYS_BOOTMAPSZ:
2758		Maximum size of memory mapped by the startup code of
2759		the Linux kernel; all data that must be processed by
2760		the Linux kernel (bd_info, boot arguments, FDT blob if
2761		used) must be put below this limit, unless "bootm_low"
2762		enviroment variable is defined and non-zero. In such case
2763		all data for the Linux kernel must be between "bootm_low"
2764		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
2765		variable "bootm_mapsize" will override the value of
2766		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
2767		then the value in "bootm_size" will be used instead.
2768
2769- CONFIG_SYS_BOOT_RAMDISK_HIGH:
2770		Enable initrd_high functionality.  If defined then the
2771		initrd_high feature is enabled and the bootm ramdisk subcommand
2772		is enabled.
2773
2774- CONFIG_SYS_BOOT_GET_CMDLINE:
2775		Enables allocating and saving kernel cmdline in space between
2776		"bootm_low" and "bootm_low" + BOOTMAPSZ.
2777
2778- CONFIG_SYS_BOOT_GET_KBD:
2779		Enables allocating and saving a kernel copy of the bd_info in
2780		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2781
2782- CONFIG_SYS_MAX_FLASH_BANKS:
2783		Max number of Flash memory banks
2784
2785- CONFIG_SYS_MAX_FLASH_SECT:
2786		Max number of sectors on a Flash chip
2787
2788- CONFIG_SYS_FLASH_ERASE_TOUT:
2789		Timeout for Flash erase operations (in ms)
2790
2791- CONFIG_SYS_FLASH_WRITE_TOUT:
2792		Timeout for Flash write operations (in ms)
2793
2794- CONFIG_SYS_FLASH_LOCK_TOUT
2795		Timeout for Flash set sector lock bit operation (in ms)
2796
2797- CONFIG_SYS_FLASH_UNLOCK_TOUT
2798		Timeout for Flash clear lock bits operation (in ms)
2799
2800- CONFIG_SYS_FLASH_PROTECTION
2801		If defined, hardware flash sectors protection is used
2802		instead of U-Boot software protection.
2803
2804- CONFIG_SYS_DIRECT_FLASH_TFTP:
2805
2806		Enable TFTP transfers directly to flash memory;
2807		without this option such a download has to be
2808		performed in two steps: (1) download to RAM, and (2)
2809		copy from RAM to flash.
2810
2811		The two-step approach is usually more reliable, since
2812		you can check if the download worked before you erase
2813		the flash, but in some situations (when system RAM is
2814		too limited to allow for a temporary copy of the
2815		downloaded image) this option may be very useful.
2816
2817- CONFIG_SYS_FLASH_CFI:
2818		Define if the flash driver uses extra elements in the
2819		common flash structure for storing flash geometry.
2820
2821- CONFIG_FLASH_CFI_DRIVER
2822		This option also enables the building of the cfi_flash driver
2823		in the drivers directory
2824
2825- CONFIG_FLASH_CFI_MTD
2826		This option enables the building of the cfi_mtd driver
2827		in the drivers directory. The driver exports CFI flash
2828		to the MTD layer.
2829
2830- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2831		Use buffered writes to flash.
2832
2833- CONFIG_FLASH_SPANSION_S29WS_N
2834		s29ws-n MirrorBit flash has non-standard addresses for buffered
2835		write commands.
2836
2837- CONFIG_SYS_FLASH_QUIET_TEST
2838		If this option is defined, the common CFI flash doesn't
2839		print it's warning upon not recognized FLASH banks. This
2840		is useful, if some of the configured banks are only
2841		optionally available.
2842
2843- CONFIG_FLASH_SHOW_PROGRESS
2844		If defined (must be an integer), print out countdown
2845		digits and dots.  Recommended value: 45 (9..1) for 80
2846		column displays, 15 (3..1) for 40 column displays.
2847
2848- CONFIG_SYS_RX_ETH_BUFFER:
2849		Defines the number of Ethernet receive buffers. On some
2850		Ethernet controllers it is recommended to set this value
2851		to 8 or even higher (EEPRO100 or 405 EMAC), since all
2852		buffers can be full shortly after enabling the interface
2853		on high Ethernet traffic.
2854		Defaults to 4 if not defined.
2855
2856- CONFIG_ENV_MAX_ENTRIES
2857
2858	Maximum number of entries in the hash table that is used
2859	internally to store the environment settings. The default
2860	setting is supposed to be generous and should work in most
2861	cases. This setting can be used to tune behaviour; see
2862	lib/hashtable.c for details.
2863
2864The following definitions that deal with the placement and management
2865of environment data (variable area); in general, we support the
2866following configurations:
2867
2868- CONFIG_BUILD_ENVCRC:
2869
2870	Builds up envcrc with the target environment so that external utils
2871	may easily extract it and embed it in final U-Boot images.
2872
2873- CONFIG_ENV_IS_IN_FLASH:
2874
2875	Define this if the environment is in flash memory.
2876
2877	a) The environment occupies one whole flash sector, which is
2878	   "embedded" in the text segment with the U-Boot code. This
2879	   happens usually with "bottom boot sector" or "top boot
2880	   sector" type flash chips, which have several smaller
2881	   sectors at the start or the end. For instance, such a
2882	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
2883	   such a case you would place the environment in one of the
2884	   4 kB sectors - with U-Boot code before and after it. With
2885	   "top boot sector" type flash chips, you would put the
2886	   environment in one of the last sectors, leaving a gap
2887	   between U-Boot and the environment.
2888
2889	- CONFIG_ENV_OFFSET:
2890
2891	   Offset of environment data (variable area) to the
2892	   beginning of flash memory; for instance, with bottom boot
2893	   type flash chips the second sector can be used: the offset
2894	   for this sector is given here.
2895
2896	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
2897
2898	- CONFIG_ENV_ADDR:
2899
2900	   This is just another way to specify the start address of
2901	   the flash sector containing the environment (instead of
2902	   CONFIG_ENV_OFFSET).
2903
2904	- CONFIG_ENV_SECT_SIZE:
2905
2906	   Size of the sector containing the environment.
2907
2908
2909	b) Sometimes flash chips have few, equal sized, BIG sectors.
2910	   In such a case you don't want to spend a whole sector for
2911	   the environment.
2912
2913	- CONFIG_ENV_SIZE:
2914
2915	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
2916	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
2917	   of this flash sector for the environment. This saves
2918	   memory for the RAM copy of the environment.
2919
2920	   It may also save flash memory if you decide to use this
2921	   when your environment is "embedded" within U-Boot code,
2922	   since then the remainder of the flash sector could be used
2923	   for U-Boot code. It should be pointed out that this is
2924	   STRONGLY DISCOURAGED from a robustness point of view:
2925	   updating the environment in flash makes it always
2926	   necessary to erase the WHOLE sector. If something goes
2927	   wrong before the contents has been restored from a copy in
2928	   RAM, your target system will be dead.
2929
2930	- CONFIG_ENV_ADDR_REDUND
2931	  CONFIG_ENV_SIZE_REDUND
2932
2933	   These settings describe a second storage area used to hold
2934	   a redundant copy of the environment data, so that there is
2935	   a valid backup copy in case there is a power failure during
2936	   a "saveenv" operation.
2937
2938BE CAREFUL! Any changes to the flash layout, and some changes to the
2939source code will make it necessary to adapt <board>/u-boot.lds*
2940accordingly!
2941
2942
2943- CONFIG_ENV_IS_IN_NVRAM:
2944
2945	Define this if you have some non-volatile memory device
2946	(NVRAM, battery buffered SRAM) which you want to use for the
2947	environment.
2948
2949	- CONFIG_ENV_ADDR:
2950	- CONFIG_ENV_SIZE:
2951
2952	  These two #defines are used to determine the memory area you
2953	  want to use for environment. It is assumed that this memory
2954	  can just be read and written to, without any special
2955	  provision.
2956
2957BE CAREFUL! The first access to the environment happens quite early
2958in U-Boot initalization (when we try to get the setting of for the
2959console baudrate). You *MUST* have mapped your NVRAM area then, or
2960U-Boot will hang.
2961
2962Please note that even with NVRAM we still use a copy of the
2963environment in RAM: we could work on NVRAM directly, but we want to
2964keep settings there always unmodified except somebody uses "saveenv"
2965to save the current settings.
2966
2967
2968- CONFIG_ENV_IS_IN_EEPROM:
2969
2970	Use this if you have an EEPROM or similar serial access
2971	device and a driver for it.
2972
2973	- CONFIG_ENV_OFFSET:
2974	- CONFIG_ENV_SIZE:
2975
2976	  These two #defines specify the offset and size of the
2977	  environment area within the total memory of your EEPROM.
2978
2979	- CONFIG_SYS_I2C_EEPROM_ADDR:
2980	  If defined, specified the chip address of the EEPROM device.
2981	  The default address is zero.
2982
2983	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
2984	  If defined, the number of bits used to address bytes in a
2985	  single page in the EEPROM device.  A 64 byte page, for example
2986	  would require six bits.
2987
2988	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
2989	  If defined, the number of milliseconds to delay between
2990	  page writes.	The default is zero milliseconds.
2991
2992	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
2993	  The length in bytes of the EEPROM memory array address.  Note
2994	  that this is NOT the chip address length!
2995
2996	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
2997	  EEPROM chips that implement "address overflow" are ones
2998	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
2999	  address and the extra bits end up in the "chip address" bit
3000	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3001	  byte chips.
3002
3003	  Note that we consider the length of the address field to
3004	  still be one byte because the extra address bits are hidden
3005	  in the chip address.
3006
3007	- CONFIG_SYS_EEPROM_SIZE:
3008	  The size in bytes of the EEPROM device.
3009
3010	- CONFIG_ENV_EEPROM_IS_ON_I2C
3011	  define this, if you have I2C and SPI activated, and your
3012	  EEPROM, which holds the environment, is on the I2C bus.
3013
3014	- CONFIG_I2C_ENV_EEPROM_BUS
3015	  if you have an Environment on an EEPROM reached over
3016	  I2C muxes, you can define here, how to reach this
3017	  EEPROM. For example:
3018
3019	  #define CONFIG_I2C_ENV_EEPROM_BUS	  "pca9547:70:d\0"
3020
3021	  EEPROM which holds the environment, is reached over
3022	  a pca9547 i2c mux with address 0x70, channel 3.
3023
3024- CONFIG_ENV_IS_IN_DATAFLASH:
3025
3026	Define this if you have a DataFlash memory device which you
3027	want to use for the environment.
3028
3029	- CONFIG_ENV_OFFSET:
3030	- CONFIG_ENV_ADDR:
3031	- CONFIG_ENV_SIZE:
3032
3033	  These three #defines specify the offset and size of the
3034	  environment area within the total memory of your DataFlash placed
3035	  at the specified address.
3036
3037- CONFIG_ENV_IS_IN_REMOTE:
3038
3039	Define this if you have a remote memory space which you
3040	want to use for the local device's environment.
3041
3042	- CONFIG_ENV_ADDR:
3043	- CONFIG_ENV_SIZE:
3044
3045	  These two #defines specify the address and size of the
3046	  environment area within the remote memory space. The
3047	  local device can get the environment from remote memory
3048	  space by SRIO or other links.
3049
3050BE CAREFUL! For some special cases, the local device can not use
3051"saveenv" command. For example, the local device will get the
3052environment stored in a remote NOR flash by SRIO link, but it can
3053not erase, write this NOR flash by SRIO interface.
3054
3055- CONFIG_ENV_IS_IN_NAND:
3056
3057	Define this if you have a NAND device which you want to use
3058	for the environment.
3059
3060	- CONFIG_ENV_OFFSET:
3061	- CONFIG_ENV_SIZE:
3062
3063	  These two #defines specify the offset and size of the environment
3064	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
3065	  aligned to an erase block boundary.
3066
3067	- CONFIG_ENV_OFFSET_REDUND (optional):
3068
3069	  This setting describes a second storage area of CONFIG_ENV_SIZE
3070	  size used to hold a redundant copy of the environment data, so
3071	  that there is a valid backup copy in case there is a power failure
3072	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
3073	  aligned to an erase block boundary.
3074
3075	- CONFIG_ENV_RANGE (optional):
3076
3077	  Specifies the length of the region in which the environment
3078	  can be written.  This should be a multiple of the NAND device's
3079	  block size.  Specifying a range with more erase blocks than
3080	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
3081	  the range to be avoided.
3082
3083	- CONFIG_ENV_OFFSET_OOB (optional):
3084
3085	  Enables support for dynamically retrieving the offset of the
3086	  environment from block zero's out-of-band data.  The
3087	  "nand env.oob" command can be used to record this offset.
3088	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
3089	  using CONFIG_ENV_OFFSET_OOB.
3090
3091- CONFIG_NAND_ENV_DST
3092
3093	Defines address in RAM to which the nand_spl code should copy the
3094	environment. If redundant environment is used, it will be copied to
3095	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3096
3097- CONFIG_SYS_SPI_INIT_OFFSET
3098
3099	Defines offset to the initial SPI buffer area in DPRAM. The
3100	area is used at an early stage (ROM part) if the environment
3101	is configured to reside in the SPI EEPROM: We need a 520 byte
3102	scratch DPRAM area. It is used between the two initialization
3103	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
3104	to be a good choice since it makes it far enough from the
3105	start of the data area as well as from the stack pointer.
3106
3107Please note that the environment is read-only until the monitor
3108has been relocated to RAM and a RAM copy of the environment has been
3109created; also, when using EEPROM you will have to use getenv_f()
3110until then to read environment variables.
3111
3112The environment is protected by a CRC32 checksum. Before the monitor
3113is relocated into RAM, as a result of a bad CRC you will be working
3114with the compiled-in default environment - *silently*!!! [This is
3115necessary, because the first environment variable we need is the
3116"baudrate" setting for the console - if we have a bad CRC, we don't
3117have any device yet where we could complain.]
3118
3119Note: once the monitor has been relocated, then it will complain if
3120the default environment is used; a new CRC is computed as soon as you
3121use the "saveenv" command to store a valid environment.
3122
3123- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
3124		Echo the inverted Ethernet link state to the fault LED.
3125
3126		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
3127		      also needs to be defined.
3128
3129- CONFIG_SYS_FAULT_MII_ADDR:
3130		MII address of the PHY to check for the Ethernet link state.
3131
3132- CONFIG_NS16550_MIN_FUNCTIONS:
3133		Define this if you desire to only have use of the NS16550_init
3134		and NS16550_putc functions for the serial driver located at
3135		drivers/serial/ns16550.c.  This option is useful for saving
3136		space for already greatly restricted images, including but not
3137		limited to NAND_SPL configurations.
3138
3139Low Level (hardware related) configuration options:
3140---------------------------------------------------
3141
3142- CONFIG_SYS_CACHELINE_SIZE:
3143		Cache Line Size of the CPU.
3144
3145- CONFIG_SYS_DEFAULT_IMMR:
3146		Default address of the IMMR after system reset.
3147
3148		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
3149		and RPXsuper) to be able to adjust the position of
3150		the IMMR register after a reset.
3151
3152- CONFIG_SYS_CCSRBAR_DEFAULT:
3153		Default (power-on reset) physical address of CCSR on Freescale
3154		PowerPC SOCs.
3155
3156- CONFIG_SYS_CCSRBAR:
3157		Virtual address of CCSR.  On a 32-bit build, this is typically
3158		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
3159
3160		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
3161		for cross-platform code that uses that macro instead.
3162
3163- CONFIG_SYS_CCSRBAR_PHYS:
3164		Physical address of CCSR.  CCSR can be relocated to a new
3165		physical address, if desired.  In this case, this macro should
3166		be set to that address.	 Otherwise, it should be set to the
3167		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
3168		is typically relocated on 36-bit builds.  It is recommended
3169		that this macro be defined via the _HIGH and _LOW macros:
3170
3171		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
3172			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
3173
3174- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
3175		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
3176		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
3177		used in assembly code, so it must not contain typecasts or
3178		integer size suffixes (e.g. "ULL").
3179
3180- CONFIG_SYS_CCSRBAR_PHYS_LOW:
3181		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
3182		used in assembly code, so it must not contain typecasts or
3183		integer size suffixes (e.g. "ULL").
3184
3185- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
3186		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
3187		forced to a value that ensures that CCSR is not relocated.
3188
3189- Floppy Disk Support:
3190		CONFIG_SYS_FDC_DRIVE_NUMBER
3191
3192		the default drive number (default value 0)
3193
3194		CONFIG_SYS_ISA_IO_STRIDE
3195
3196		defines the spacing between FDC chipset registers
3197		(default value 1)
3198
3199		CONFIG_SYS_ISA_IO_OFFSET
3200
3201		defines the offset of register from address. It
3202		depends on which part of the data bus is connected to
3203		the FDC chipset. (default value 0)
3204
3205		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
3206		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
3207		default value.
3208
3209		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
3210		fdc_hw_init() is called at the beginning of the FDC
3211		setup. fdc_hw_init() must be provided by the board
3212		source code. It is used to make hardware dependant
3213		initializations.
3214
3215- CONFIG_IDE_AHB:
3216		Most IDE controllers were designed to be connected with PCI
3217		interface. Only few of them were designed for AHB interface.
3218		When software is doing ATA command and data transfer to
3219		IDE devices through IDE-AHB controller, some additional
3220		registers accessing to these kind of IDE-AHB controller
3221		is requierd.
3222
3223- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
3224		DO NOT CHANGE unless you know exactly what you're
3225		doing! (11-4) [MPC8xx/82xx systems only]
3226
3227- CONFIG_SYS_INIT_RAM_ADDR:
3228
3229		Start address of memory area that can be used for
3230		initial data and stack; please note that this must be
3231		writable memory that is working WITHOUT special
3232		initialization, i. e. you CANNOT use normal RAM which
3233		will become available only after programming the
3234		memory controller and running certain initialization
3235		sequences.
3236
3237		U-Boot uses the following memory types:
3238		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
3239		- MPC824X: data cache
3240		- PPC4xx:  data cache
3241
3242- CONFIG_SYS_GBL_DATA_OFFSET:
3243
3244		Offset of the initial data structure in the memory
3245		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
3246		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
3247		data is located at the end of the available space
3248		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
3249		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
3250		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
3251		CONFIG_SYS_GBL_DATA_OFFSET) downward.
3252
3253	Note:
3254		On the MPC824X (or other systems that use the data
3255		cache for initial memory) the address chosen for
3256		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
3257		point to an otherwise UNUSED address space between
3258		the top of RAM and the start of the PCI space.
3259
3260- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
3261
3262- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
3263
3264- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
3265
3266- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
3267
3268- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
3269
3270- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
3271
3272- CONFIG_SYS_OR_TIMING_SDRAM:
3273		SDRAM timing
3274
3275- CONFIG_SYS_MAMR_PTA:
3276		periodic timer for refresh
3277
3278- CONFIG_SYS_DER:	Debug Event Register (37-47)
3279
3280- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
3281  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
3282  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
3283  CONFIG_SYS_BR1_PRELIM:
3284		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
3285
3286- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
3287  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
3288  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
3289		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
3290
3291- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
3292  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
3293		Machine Mode Register and Memory Periodic Timer
3294		Prescaler definitions (SDRAM timing)
3295
3296- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
3297		enable I2C microcode relocation patch (MPC8xx);
3298		define relocation offset in DPRAM [DSP2]
3299
3300- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
3301		enable SMC microcode relocation patch (MPC8xx);
3302		define relocation offset in DPRAM [SMC1]
3303
3304- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
3305		enable SPI microcode relocation patch (MPC8xx);
3306		define relocation offset in DPRAM [SCC4]
3307
3308- CONFIG_SYS_USE_OSCCLK:
3309		Use OSCM clock mode on MBX8xx board. Be careful,
3310		wrong setting might damage your board. Read
3311		doc/README.MBX before setting this variable!
3312
3313- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
3314		Offset of the bootmode word in DPRAM used by post
3315		(Power On Self Tests). This definition overrides
3316		#define'd default value in commproc.h resp.
3317		cpm_8260.h.
3318
3319- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
3320  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
3321  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
3322  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
3323  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
3324  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
3325  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
3326  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
3327		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
3328
3329- CONFIG_PCI_DISABLE_PCIE:
3330		Disable PCI-Express on systems where it is supported but not
3331		required.
3332
3333- CONFIG_SYS_SRIO:
3334		Chip has SRIO or not
3335
3336- CONFIG_SRIO1:
3337		Board has SRIO 1 port available
3338
3339- CONFIG_SRIO2:
3340		Board has SRIO 2 port available
3341
3342- CONFIG_SYS_SRIOn_MEM_VIRT:
3343		Virtual Address of SRIO port 'n' memory region
3344
3345- CONFIG_SYS_SRIOn_MEM_PHYS:
3346		Physical Address of SRIO port 'n' memory region
3347
3348- CONFIG_SYS_SRIOn_MEM_SIZE:
3349		Size of SRIO port 'n' memory region
3350
3351- CONFIG_SYS_NDFC_16
3352		Defined to tell the NDFC that the NAND chip is using a
3353		16 bit bus.
3354
3355- CONFIG_SYS_NDFC_EBC0_CFG
3356		Sets the EBC0_CFG register for the NDFC. If not defined
3357		a default value will be used.
3358
3359- CONFIG_SPD_EEPROM
3360		Get DDR timing information from an I2C EEPROM. Common
3361		with pluggable memory modules such as SODIMMs
3362
3363  SPD_EEPROM_ADDRESS
3364		I2C address of the SPD EEPROM
3365
3366- CONFIG_SYS_SPD_BUS_NUM
3367		If SPD EEPROM is on an I2C bus other than the first
3368		one, specify here. Note that the value must resolve
3369		to something your driver can deal with.
3370
3371- CONFIG_SYS_DDR_RAW_TIMING
3372		Get DDR timing information from other than SPD. Common with
3373		soldered DDR chips onboard without SPD. DDR raw timing
3374		parameters are extracted from datasheet and hard-coded into
3375		header files or board specific files.
3376
3377- CONFIG_FSL_DDR_INTERACTIVE
3378		Enable interactive DDR debugging. See doc/README.fsl-ddr.
3379
3380- CONFIG_SYS_83XX_DDR_USES_CS0
3381		Only for 83xx systems. If specified, then DDR should
3382		be configured using CS0 and CS1 instead of CS2 and CS3.
3383
3384- CONFIG_ETHER_ON_FEC[12]
3385		Define to enable FEC[12] on a 8xx series processor.
3386
3387- CONFIG_FEC[12]_PHY
3388		Define to the hardcoded PHY address which corresponds
3389		to the given FEC; i. e.
3390			#define CONFIG_FEC1_PHY 4
3391		means that the PHY with address 4 is connected to FEC1
3392
3393		When set to -1, means to probe for first available.
3394
3395- CONFIG_FEC[12]_PHY_NORXERR
3396		The PHY does not have a RXERR line (RMII only).
3397		(so program the FEC to ignore it).
3398
3399- CONFIG_RMII
3400		Enable RMII mode for all FECs.
3401		Note that this is a global option, we can't
3402		have one FEC in standard MII mode and another in RMII mode.
3403
3404- CONFIG_CRC32_VERIFY
3405		Add a verify option to the crc32 command.
3406		The syntax is:
3407
3408		=> crc32 -v <address> <count> <crc32>
3409
3410		Where address/count indicate a memory area
3411		and crc32 is the correct crc32 which the
3412		area should have.
3413
3414- CONFIG_LOOPW
3415		Add the "loopw" memory command. This only takes effect if
3416		the memory commands are activated globally (CONFIG_CMD_MEM).
3417
3418- CONFIG_MX_CYCLIC
3419		Add the "mdc" and "mwc" memory commands. These are cyclic
3420		"md/mw" commands.
3421		Examples:
3422
3423		=> mdc.b 10 4 500
3424		This command will print 4 bytes (10,11,12,13) each 500 ms.
3425
3426		=> mwc.l 100 12345678 10
3427		This command will write 12345678 to address 100 all 10 ms.
3428
3429		This only takes effect if the memory commands are activated
3430		globally (CONFIG_CMD_MEM).
3431
3432- CONFIG_SKIP_LOWLEVEL_INIT
3433		[ARM, NDS32, MIPS only] If this variable is defined, then certain
3434		low level initializations (like setting up the memory
3435		controller) are omitted and/or U-Boot does not
3436		relocate itself into RAM.
3437
3438		Normally this variable MUST NOT be defined. The only
3439		exception is when U-Boot is loaded (to RAM) by some
3440		other boot loader or by a debugger which performs
3441		these initializations itself.
3442
3443- CONFIG_SPL_BUILD
3444		Modifies the behaviour of start.S when compiling a loader
3445		that is executed before the actual U-Boot. E.g. when
3446		compiling a NAND SPL.
3447
3448- CONFIG_USE_ARCH_MEMCPY
3449  CONFIG_USE_ARCH_MEMSET
3450		If these options are used a optimized version of memcpy/memset will
3451		be used if available. These functions may be faster under some
3452		conditions but may increase the binary size.
3453
3454Freescale QE/FMAN Firmware Support:
3455-----------------------------------
3456
3457The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
3458loading of "firmware", which is encoded in the QE firmware binary format.
3459This firmware often needs to be loaded during U-Boot booting, so macros
3460are used to identify the storage device (NOR flash, SPI, etc) and the address
3461within that device.
3462
3463- CONFIG_SYS_QE_FMAN_FW_ADDR
3464	The address in the storage device where the firmware is located.  The
3465	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
3466	is also specified.
3467
3468- CONFIG_SYS_QE_FMAN_FW_LENGTH
3469	The maximum possible size of the firmware.  The firmware binary format
3470	has a field that specifies the actual size of the firmware, but it
3471	might not be possible to read any part of the firmware unless some
3472	local storage is allocated to hold the entire firmware first.
3473
3474- CONFIG_SYS_QE_FMAN_FW_IN_NOR
3475	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
3476	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
3477	virtual address in NOR flash.
3478
3479- CONFIG_SYS_QE_FMAN_FW_IN_NAND
3480	Specifies that QE/FMAN firmware is located in NAND flash.
3481	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
3482
3483- CONFIG_SYS_QE_FMAN_FW_IN_MMC
3484	Specifies that QE/FMAN firmware is located on the primary SD/MMC
3485	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3486
3487- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
3488	Specifies that QE/FMAN firmware is located on the primary SPI
3489	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3490
3491- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
3492	Specifies that QE/FMAN firmware is located in the remote (master)
3493	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
3494	can be mapped from slave TLB->slave LAW->slave SRIO outbound window
3495	->master inbound window->master LAW->the ucode address in master's
3496	NOR flash.
3497
3498Building the Software:
3499======================
3500
3501Building U-Boot has been tested in several native build environments
3502and in many different cross environments. Of course we cannot support
3503all possibly existing versions of cross development tools in all
3504(potentially obsolete) versions. In case of tool chain problems we
3505recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
3506which is extensively used to build and test U-Boot.
3507
3508If you are not using a native environment, it is assumed that you
3509have GNU cross compiling tools available in your path. In this case,
3510you must set the environment variable CROSS_COMPILE in your shell.
3511Note that no changes to the Makefile or any other source files are
3512necessary. For example using the ELDK on a 4xx CPU, please enter:
3513
3514	$ CROSS_COMPILE=ppc_4xx-
3515	$ export CROSS_COMPILE
3516
3517Note: If you wish to generate Windows versions of the utilities in
3518      the tools directory you can use the MinGW toolchain
3519      (http://www.mingw.org).  Set your HOST tools to the MinGW
3520      toolchain and execute 'make tools'.  For example:
3521
3522       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
3523
3524      Binaries such as tools/mkimage.exe will be created which can
3525      be executed on computers running Windows.
3526
3527U-Boot is intended to be simple to build. After installing the
3528sources you must configure U-Boot for one specific board type. This
3529is done by typing:
3530
3531	make NAME_config
3532
3533where "NAME_config" is the name of one of the existing configu-
3534rations; see boards.cfg for supported names.
3535
3536Note: for some board special configuration names may exist; check if
3537      additional information is available from the board vendor; for
3538      instance, the TQM823L systems are available without (standard)
3539      or with LCD support. You can select such additional "features"
3540      when choosing the configuration, i. e.
3541
3542      make TQM823L_config
3543	- will configure for a plain TQM823L, i. e. no LCD support
3544
3545      make TQM823L_LCD_config
3546	- will configure for a TQM823L with U-Boot console on LCD
3547
3548      etc.
3549
3550
3551Finally, type "make all", and you should get some working U-Boot
3552images ready for download to / installation on your system:
3553
3554- "u-boot.bin" is a raw binary image
3555- "u-boot" is an image in ELF binary format
3556- "u-boot.srec" is in Motorola S-Record format
3557
3558By default the build is performed locally and the objects are saved
3559in the source directory. One of the two methods can be used to change
3560this behavior and build U-Boot to some external directory:
3561
35621. Add O= to the make command line invocations:
3563
3564	make O=/tmp/build distclean
3565	make O=/tmp/build NAME_config
3566	make O=/tmp/build all
3567
35682. Set environment variable BUILD_DIR to point to the desired location:
3569
3570	export BUILD_DIR=/tmp/build
3571	make distclean
3572	make NAME_config
3573	make all
3574
3575Note that the command line "O=" setting overrides the BUILD_DIR environment
3576variable.
3577
3578
3579Please be aware that the Makefiles assume you are using GNU make, so
3580for instance on NetBSD you might need to use "gmake" instead of
3581native "make".
3582
3583
3584If the system board that you have is not listed, then you will need
3585to port U-Boot to your hardware platform. To do this, follow these
3586steps:
3587
35881.  Add a new configuration option for your board to the toplevel
3589    "boards.cfg" file, using the existing entries as examples.
3590    Follow the instructions there to keep the boards in order.
35912.  Create a new directory to hold your board specific code. Add any
3592    files you need. In your board directory, you will need at least
3593    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
35943.  Create a new configuration file "include/configs/<board>.h" for
3595    your board
35963.  If you're porting U-Boot to a new CPU, then also create a new
3597    directory to hold your CPU specific code. Add any files you need.
35984.  Run "make <board>_config" with your new name.
35995.  Type "make", and you should get a working "u-boot.srec" file
3600    to be installed on your target system.
36016.  Debug and solve any problems that might arise.
3602    [Of course, this last step is much harder than it sounds.]
3603
3604
3605Testing of U-Boot Modifications, Ports to New Hardware, etc.:
3606==============================================================
3607
3608If you have modified U-Boot sources (for instance added a new board
3609or support for new devices, a new CPU, etc.) you are expected to
3610provide feedback to the other developers. The feedback normally takes
3611the form of a "patch", i. e. a context diff against a certain (latest
3612official or latest in the git repository) version of U-Boot sources.
3613
3614But before you submit such a patch, please verify that your modifi-
3615cation did not break existing code. At least make sure that *ALL* of
3616the supported boards compile WITHOUT ANY compiler warnings. To do so,
3617just run the "MAKEALL" script, which will configure and build U-Boot
3618for ALL supported system. Be warned, this will take a while. You can
3619select which (cross) compiler to use by passing a `CROSS_COMPILE'
3620environment variable to the script, i. e. to use the ELDK cross tools
3621you can type
3622
3623	CROSS_COMPILE=ppc_8xx- MAKEALL
3624
3625or to build on a native PowerPC system you can type
3626
3627	CROSS_COMPILE=' ' MAKEALL
3628
3629When using the MAKEALL script, the default behaviour is to build
3630U-Boot in the source directory. This location can be changed by
3631setting the BUILD_DIR environment variable. Also, for each target
3632built, the MAKEALL script saves two log files (<target>.ERR and
3633<target>.MAKEALL) in the <source dir>/LOG directory. This default
3634location can be changed by setting the MAKEALL_LOGDIR environment
3635variable. For example:
3636
3637	export BUILD_DIR=/tmp/build
3638	export MAKEALL_LOGDIR=/tmp/log
3639	CROSS_COMPILE=ppc_8xx- MAKEALL
3640
3641With the above settings build objects are saved in the /tmp/build,
3642log files are saved in the /tmp/log and the source tree remains clean
3643during the whole build process.
3644
3645
3646See also "U-Boot Porting Guide" below.
3647
3648
3649Monitor Commands - Overview:
3650============================
3651
3652go	- start application at address 'addr'
3653run	- run commands in an environment variable
3654bootm	- boot application image from memory
3655bootp	- boot image via network using BootP/TFTP protocol
3656bootz   - boot zImage from memory
3657tftpboot- boot image via network using TFTP protocol
3658	       and env variables "ipaddr" and "serverip"
3659	       (and eventually "gatewayip")
3660tftpput - upload a file via network using TFTP protocol
3661rarpboot- boot image via network using RARP/TFTP protocol
3662diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
3663loads	- load S-Record file over serial line
3664loadb	- load binary file over serial line (kermit mode)
3665md	- memory display
3666mm	- memory modify (auto-incrementing)
3667nm	- memory modify (constant address)
3668mw	- memory write (fill)
3669cp	- memory copy
3670cmp	- memory compare
3671crc32	- checksum calculation
3672i2c	- I2C sub-system
3673sspi	- SPI utility commands
3674base	- print or set address offset
3675printenv- print environment variables
3676setenv	- set environment variables
3677saveenv - save environment variables to persistent storage
3678protect - enable or disable FLASH write protection
3679erase	- erase FLASH memory
3680flinfo	- print FLASH memory information
3681bdinfo	- print Board Info structure
3682iminfo	- print header information for application image
3683coninfo - print console devices and informations
3684ide	- IDE sub-system
3685loop	- infinite loop on address range
3686loopw	- infinite write loop on address range
3687mtest	- simple RAM test
3688icache	- enable or disable instruction cache
3689dcache	- enable or disable data cache
3690reset	- Perform RESET of the CPU
3691echo	- echo args to console
3692version - print monitor version
3693help	- print online help
3694?	- alias for 'help'
3695
3696
3697Monitor Commands - Detailed Description:
3698========================================
3699
3700TODO.
3701
3702For now: just type "help <command>".
3703
3704
3705Environment Variables:
3706======================
3707
3708U-Boot supports user configuration using Environment Variables which
3709can be made persistent by saving to Flash memory.
3710
3711Environment Variables are set using "setenv", printed using
3712"printenv", and saved to Flash using "saveenv". Using "setenv"
3713without a value can be used to delete a variable from the
3714environment. As long as you don't save the environment you are
3715working with an in-memory copy. In case the Flash area containing the
3716environment is erased by accident, a default environment is provided.
3717
3718Some configuration options can be set using Environment Variables.
3719
3720List of environment variables (most likely not complete):
3721
3722  baudrate	- see CONFIG_BAUDRATE
3723
3724  bootdelay	- see CONFIG_BOOTDELAY
3725
3726  bootcmd	- see CONFIG_BOOTCOMMAND
3727
3728  bootargs	- Boot arguments when booting an RTOS image
3729
3730  bootfile	- Name of the image to load with TFTP
3731
3732  bootm_low	- Memory range available for image processing in the bootm
3733		  command can be restricted. This variable is given as
3734		  a hexadecimal number and defines lowest address allowed
3735		  for use by the bootm command. See also "bootm_size"
3736		  environment variable. Address defined by "bootm_low" is
3737		  also the base of the initial memory mapping for the Linux
3738		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
3739		  bootm_mapsize.
3740
3741  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
3742		  This variable is given as a hexadecimal number and it
3743		  defines the size of the memory region starting at base
3744		  address bootm_low that is accessible by the Linux kernel
3745		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
3746		  as the default value if it is defined, and bootm_size is
3747		  used otherwise.
3748
3749  bootm_size	- Memory range available for image processing in the bootm
3750		  command can be restricted. This variable is given as
3751		  a hexadecimal number and defines the size of the region
3752		  allowed for use by the bootm command. See also "bootm_low"
3753		  environment variable.
3754
3755  updatefile	- Location of the software update file on a TFTP server, used
3756		  by the automatic software update feature. Please refer to
3757		  documentation in doc/README.update for more details.
3758
3759  autoload	- if set to "no" (any string beginning with 'n'),
3760		  "bootp" will just load perform a lookup of the
3761		  configuration from the BOOTP server, but not try to
3762		  load any image using TFTP
3763
3764  autostart	- if set to "yes", an image loaded using the "bootp",
3765		  "rarpboot", "tftpboot" or "diskboot" commands will
3766		  be automatically started (by internally calling
3767		  "bootm")
3768
3769		  If set to "no", a standalone image passed to the
3770		  "bootm" command will be copied to the load address
3771		  (and eventually uncompressed), but NOT be started.
3772		  This can be used to load and uncompress arbitrary
3773		  data.
3774
3775  fdt_high	- if set this restricts the maximum address that the
3776		  flattened device tree will be copied into upon boot.
3777		  For example, if you have a system with 1 GB memory
3778		  at physical address 0x10000000, while Linux kernel
3779		  only recognizes the first 704 MB as low memory, you
3780		  may need to set fdt_high as 0x3C000000 to have the
3781		  device tree blob be copied to the maximum address
3782		  of the 704 MB low memory, so that Linux kernel can
3783		  access it during the boot procedure.
3784
3785		  If this is set to the special value 0xFFFFFFFF then
3786		  the fdt will not be copied at all on boot.  For this
3787		  to work it must reside in writable memory, have
3788		  sufficient padding on the end of it for u-boot to
3789		  add the information it needs into it, and the memory
3790		  must be accessible by the kernel.
3791
3792  fdtcontroladdr- if set this is the address of the control flattened
3793		  device tree used by U-Boot when CONFIG_OF_CONTROL is
3794		  defined.
3795
3796  i2cfast	- (PPC405GP|PPC405EP only)
3797		  if set to 'y' configures Linux I2C driver for fast
3798		  mode (400kHZ). This environment variable is used in
3799		  initialization code. So, for changes to be effective
3800		  it must be saved and board must be reset.
3801
3802  initrd_high	- restrict positioning of initrd images:
3803		  If this variable is not set, initrd images will be
3804		  copied to the highest possible address in RAM; this
3805		  is usually what you want since it allows for
3806		  maximum initrd size. If for some reason you want to
3807		  make sure that the initrd image is loaded below the
3808		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3809		  variable to a value of "no" or "off" or "0".
3810		  Alternatively, you can set it to a maximum upper
3811		  address to use (U-Boot will still check that it
3812		  does not overwrite the U-Boot stack and data).
3813
3814		  For instance, when you have a system with 16 MB
3815		  RAM, and want to reserve 4 MB from use by Linux,
3816		  you can do this by adding "mem=12M" to the value of
3817		  the "bootargs" variable. However, now you must make
3818		  sure that the initrd image is placed in the first
3819		  12 MB as well - this can be done with
3820
3821		  setenv initrd_high 00c00000
3822
3823		  If you set initrd_high to 0xFFFFFFFF, this is an
3824		  indication to U-Boot that all addresses are legal
3825		  for the Linux kernel, including addresses in flash
3826		  memory. In this case U-Boot will NOT COPY the
3827		  ramdisk at all. This may be useful to reduce the
3828		  boot time on your system, but requires that this
3829		  feature is supported by your Linux kernel.
3830
3831  ipaddr	- IP address; needed for tftpboot command
3832
3833  loadaddr	- Default load address for commands like "bootp",
3834		  "rarpboot", "tftpboot", "loadb" or "diskboot"
3835
3836  loads_echo	- see CONFIG_LOADS_ECHO
3837
3838  serverip	- TFTP server IP address; needed for tftpboot command
3839
3840  bootretry	- see CONFIG_BOOT_RETRY_TIME
3841
3842  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
3843
3844  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
3845
3846  ethprime	- controls which interface is used first.
3847
3848  ethact	- controls which interface is currently active.
3849		  For example you can do the following
3850
3851		  => setenv ethact FEC
3852		  => ping 192.168.0.1 # traffic sent on FEC
3853		  => setenv ethact SCC
3854		  => ping 10.0.0.1 # traffic sent on SCC
3855
3856  ethrotate	- When set to "no" U-Boot does not go through all
3857		  available network interfaces.
3858		  It just stays at the currently selected interface.
3859
3860  netretry	- When set to "no" each network operation will
3861		  either succeed or fail without retrying.
3862		  When set to "once" the network operation will
3863		  fail when all the available network interfaces
3864		  are tried once without success.
3865		  Useful on scripts which control the retry operation
3866		  themselves.
3867
3868  npe_ucode	- set load address for the NPE microcode
3869
3870  tftpsrcport	- If this is set, the value is used for TFTP's
3871		  UDP source port.
3872
3873  tftpdstport	- If this is set, the value is used for TFTP's UDP
3874		  destination port instead of the Well Know Port 69.
3875
3876  tftpblocksize - Block size to use for TFTP transfers; if not set,
3877		  we use the TFTP server's default block size
3878
3879  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
3880		  seconds, minimum value is 1000 = 1 second). Defines
3881		  when a packet is considered to be lost so it has to
3882		  be retransmitted. The default is 5000 = 5 seconds.
3883		  Lowering this value may make downloads succeed
3884		  faster in networks with high packet loss rates or
3885		  with unreliable TFTP servers.
3886
3887  vlan		- When set to a value < 4095 the traffic over
3888		  Ethernet is encapsulated/received over 802.1q
3889		  VLAN tagged frames.
3890
3891The following image location variables contain the location of images
3892used in booting. The "Image" column gives the role of the image and is
3893not an environment variable name. The other columns are environment
3894variable names. "File Name" gives the name of the file on a TFTP
3895server, "RAM Address" gives the location in RAM the image will be
3896loaded to, and "Flash Location" gives the image's address in NOR
3897flash or offset in NAND flash.
3898
3899*Note* - these variables don't have to be defined for all boards, some
3900boards currenlty use other variables for these purposes, and some
3901boards use these variables for other purposes.
3902
3903Image		    File Name	     RAM Address       Flash Location
3904-----		    ---------	     -----------       --------------
3905u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
3906Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
3907device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
3908ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
3909
3910The following environment variables may be used and automatically
3911updated by the network boot commands ("bootp" and "rarpboot"),
3912depending the information provided by your boot server:
3913
3914  bootfile	- see above
3915  dnsip		- IP address of your Domain Name Server
3916  dnsip2	- IP address of your secondary Domain Name Server
3917  gatewayip	- IP address of the Gateway (Router) to use
3918  hostname	- Target hostname
3919  ipaddr	- see above
3920  netmask	- Subnet Mask
3921  rootpath	- Pathname of the root filesystem on the NFS server
3922  serverip	- see above
3923
3924
3925There are two special Environment Variables:
3926
3927  serial#	- contains hardware identification information such
3928		  as type string and/or serial number
3929  ethaddr	- Ethernet address
3930
3931These variables can be set only once (usually during manufacturing of
3932the board). U-Boot refuses to delete or overwrite these variables
3933once they have been set once.
3934
3935
3936Further special Environment Variables:
3937
3938  ver		- Contains the U-Boot version string as printed
3939		  with the "version" command. This variable is
3940		  readonly (see CONFIG_VERSION_VARIABLE).
3941
3942
3943Please note that changes to some configuration parameters may take
3944only effect after the next boot (yes, that's just like Windoze :-).
3945
3946
3947Command Line Parsing:
3948=====================
3949
3950There are two different command line parsers available with U-Boot:
3951the old "simple" one, and the much more powerful "hush" shell:
3952
3953Old, simple command line parser:
3954--------------------------------
3955
3956- supports environment variables (through setenv / saveenv commands)
3957- several commands on one line, separated by ';'
3958- variable substitution using "... ${name} ..." syntax
3959- special characters ('$', ';') can be escaped by prefixing with '\',
3960  for example:
3961	setenv bootcmd bootm \${address}
3962- You can also escape text by enclosing in single apostrophes, for example:
3963	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
3964
3965Hush shell:
3966-----------
3967
3968- similar to Bourne shell, with control structures like
3969  if...then...else...fi, for...do...done; while...do...done,
3970  until...do...done, ...
3971- supports environment ("global") variables (through setenv / saveenv
3972  commands) and local shell variables (through standard shell syntax
3973  "name=value"); only environment variables can be used with "run"
3974  command
3975
3976General rules:
3977--------------
3978
3979(1) If a command line (or an environment variable executed by a "run"
3980    command) contains several commands separated by semicolon, and
3981    one of these commands fails, then the remaining commands will be
3982    executed anyway.
3983
3984(2) If you execute several variables with one call to run (i. e.
3985    calling run with a list of variables as arguments), any failing
3986    command will cause "run" to terminate, i. e. the remaining
3987    variables are not executed.
3988
3989Note for Redundant Ethernet Interfaces:
3990=======================================
3991
3992Some boards come with redundant Ethernet interfaces; U-Boot supports
3993such configurations and is capable of automatic selection of a
3994"working" interface when needed. MAC assignment works as follows:
3995
3996Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
3997MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
3998"eth1addr" (=>eth1), "eth2addr", ...
3999
4000If the network interface stores some valid MAC address (for instance
4001in SROM), this is used as default address if there is NO correspon-
4002ding setting in the environment; if the corresponding environment
4003variable is set, this overrides the settings in the card; that means:
4004
4005o If the SROM has a valid MAC address, and there is no address in the
4006  environment, the SROM's address is used.
4007
4008o If there is no valid address in the SROM, and a definition in the
4009  environment exists, then the value from the environment variable is
4010  used.
4011
4012o If both the SROM and the environment contain a MAC address, and
4013  both addresses are the same, this MAC address is used.
4014
4015o If both the SROM and the environment contain a MAC address, and the
4016  addresses differ, the value from the environment is used and a
4017  warning is printed.
4018
4019o If neither SROM nor the environment contain a MAC address, an error
4020  is raised.
4021
4022If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
4023will be programmed into hardware as part of the initialization process.	 This
4024may be skipped by setting the appropriate 'ethmacskip' environment variable.
4025The naming convention is as follows:
4026"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
4027
4028Image Formats:
4029==============
4030
4031U-Boot is capable of booting (and performing other auxiliary operations on)
4032images in two formats:
4033
4034New uImage format (FIT)
4035-----------------------
4036
4037Flexible and powerful format based on Flattened Image Tree -- FIT (similar
4038to Flattened Device Tree). It allows the use of images with multiple
4039components (several kernels, ramdisks, etc.), with contents protected by
4040SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
4041
4042
4043Old uImage format
4044-----------------
4045
4046Old image format is based on binary files which can be basically anything,
4047preceded by a special header; see the definitions in include/image.h for
4048details; basically, the header defines the following image properties:
4049
4050* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
4051  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
4052  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
4053  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
4054  INTEGRITY).
4055* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
4056  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
4057  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
4058* Compression Type (uncompressed, gzip, bzip2)
4059* Load Address
4060* Entry Point
4061* Image Name
4062* Image Timestamp
4063
4064The header is marked by a special Magic Number, and both the header
4065and the data portions of the image are secured against corruption by
4066CRC32 checksums.
4067
4068
4069Linux Support:
4070==============
4071
4072Although U-Boot should support any OS or standalone application
4073easily, the main focus has always been on Linux during the design of
4074U-Boot.
4075
4076U-Boot includes many features that so far have been part of some
4077special "boot loader" code within the Linux kernel. Also, any
4078"initrd" images to be used are no longer part of one big Linux image;
4079instead, kernel and "initrd" are separate images. This implementation
4080serves several purposes:
4081
4082- the same features can be used for other OS or standalone
4083  applications (for instance: using compressed images to reduce the
4084  Flash memory footprint)
4085
4086- it becomes much easier to port new Linux kernel versions because
4087  lots of low-level, hardware dependent stuff are done by U-Boot
4088
4089- the same Linux kernel image can now be used with different "initrd"
4090  images; of course this also means that different kernel images can
4091  be run with the same "initrd". This makes testing easier (you don't
4092  have to build a new "zImage.initrd" Linux image when you just
4093  change a file in your "initrd"). Also, a field-upgrade of the
4094  software is easier now.
4095
4096
4097Linux HOWTO:
4098============
4099
4100Porting Linux to U-Boot based systems:
4101---------------------------------------
4102
4103U-Boot cannot save you from doing all the necessary modifications to
4104configure the Linux device drivers for use with your target hardware
4105(no, we don't intend to provide a full virtual machine interface to
4106Linux :-).
4107
4108But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
4109
4110Just make sure your machine specific header file (for instance
4111include/asm-ppc/tqm8xx.h) includes the same definition of the Board
4112Information structure as we define in include/asm-<arch>/u-boot.h,
4113and make sure that your definition of IMAP_ADDR uses the same value
4114as your U-Boot configuration in CONFIG_SYS_IMMR.
4115
4116
4117Configuring the Linux kernel:
4118-----------------------------
4119
4120No specific requirements for U-Boot. Make sure you have some root
4121device (initial ramdisk, NFS) for your target system.
4122
4123
4124Building a Linux Image:
4125-----------------------
4126
4127With U-Boot, "normal" build targets like "zImage" or "bzImage" are
4128not used. If you use recent kernel source, a new build target
4129"uImage" will exist which automatically builds an image usable by
4130U-Boot. Most older kernels also have support for a "pImage" target,
4131which was introduced for our predecessor project PPCBoot and uses a
4132100% compatible format.
4133
4134Example:
4135
4136	make TQM850L_config
4137	make oldconfig
4138	make dep
4139	make uImage
4140
4141The "uImage" build target uses a special tool (in 'tools/mkimage') to
4142encapsulate a compressed Linux kernel image with header	 information,
4143CRC32 checksum etc. for use with U-Boot. This is what we are doing:
4144
4145* build a standard "vmlinux" kernel image (in ELF binary format):
4146
4147* convert the kernel into a raw binary image:
4148
4149	${CROSS_COMPILE}-objcopy -O binary \
4150				 -R .note -R .comment \
4151				 -S vmlinux linux.bin
4152
4153* compress the binary image:
4154
4155	gzip -9 linux.bin
4156
4157* package compressed binary image for U-Boot:
4158
4159	mkimage -A ppc -O linux -T kernel -C gzip \
4160		-a 0 -e 0 -n "Linux Kernel Image" \
4161		-d linux.bin.gz uImage
4162
4163
4164The "mkimage" tool can also be used to create ramdisk images for use
4165with U-Boot, either separated from the Linux kernel image, or
4166combined into one file. "mkimage" encapsulates the images with a 64
4167byte header containing information about target architecture,
4168operating system, image type, compression method, entry points, time
4169stamp, CRC32 checksums, etc.
4170
4171"mkimage" can be called in two ways: to verify existing images and
4172print the header information, or to build new images.
4173
4174In the first form (with "-l" option) mkimage lists the information
4175contained in the header of an existing U-Boot image; this includes
4176checksum verification:
4177
4178	tools/mkimage -l image
4179	  -l ==> list image header information
4180
4181The second form (with "-d" option) is used to build a U-Boot image
4182from a "data file" which is used as image payload:
4183
4184	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
4185		      -n name -d data_file image
4186	  -A ==> set architecture to 'arch'
4187	  -O ==> set operating system to 'os'
4188	  -T ==> set image type to 'type'
4189	  -C ==> set compression type 'comp'
4190	  -a ==> set load address to 'addr' (hex)
4191	  -e ==> set entry point to 'ep' (hex)
4192	  -n ==> set image name to 'name'
4193	  -d ==> use image data from 'datafile'
4194
4195Right now, all Linux kernels for PowerPC systems use the same load
4196address (0x00000000), but the entry point address depends on the
4197kernel version:
4198
4199- 2.2.x kernels have the entry point at 0x0000000C,
4200- 2.3.x and later kernels have the entry point at 0x00000000.
4201
4202So a typical call to build a U-Boot image would read:
4203
4204	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4205	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
4206	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
4207	> examples/uImage.TQM850L
4208	Image Name:   2.4.4 kernel for TQM850L
4209	Created:      Wed Jul 19 02:34:59 2000
4210	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
4211	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
4212	Load Address: 0x00000000
4213	Entry Point:  0x00000000
4214
4215To verify the contents of the image (or check for corruption):
4216
4217	-> tools/mkimage -l examples/uImage.TQM850L
4218	Image Name:   2.4.4 kernel for TQM850L
4219	Created:      Wed Jul 19 02:34:59 2000
4220	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
4221	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
4222	Load Address: 0x00000000
4223	Entry Point:  0x00000000
4224
4225NOTE: for embedded systems where boot time is critical you can trade
4226speed for memory and install an UNCOMPRESSED image instead: this
4227needs more space in Flash, but boots much faster since it does not
4228need to be uncompressed:
4229
4230	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
4231	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4232	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
4233	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
4234	> examples/uImage.TQM850L-uncompressed
4235	Image Name:   2.4.4 kernel for TQM850L
4236	Created:      Wed Jul 19 02:34:59 2000
4237	Image Type:   PowerPC Linux Kernel Image (uncompressed)
4238	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
4239	Load Address: 0x00000000
4240	Entry Point:  0x00000000
4241
4242
4243Similar you can build U-Boot images from a 'ramdisk.image.gz' file
4244when your kernel is intended to use an initial ramdisk:
4245
4246	-> tools/mkimage -n 'Simple Ramdisk Image' \
4247	> -A ppc -O linux -T ramdisk -C gzip \
4248	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
4249	Image Name:   Simple Ramdisk Image
4250	Created:      Wed Jan 12 14:01:50 2000
4251	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
4252	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
4253	Load Address: 0x00000000
4254	Entry Point:  0x00000000
4255
4256
4257Installing a Linux Image:
4258-------------------------
4259
4260To downloading a U-Boot image over the serial (console) interface,
4261you must convert the image to S-Record format:
4262
4263	objcopy -I binary -O srec examples/image examples/image.srec
4264
4265The 'objcopy' does not understand the information in the U-Boot
4266image header, so the resulting S-Record file will be relative to
4267address 0x00000000. To load it to a given address, you need to
4268specify the target address as 'offset' parameter with the 'loads'
4269command.
4270
4271Example: install the image to address 0x40100000 (which on the
4272TQM8xxL is in the first Flash bank):
4273
4274	=> erase 40100000 401FFFFF
4275
4276	.......... done
4277	Erased 8 sectors
4278
4279	=> loads 40100000
4280	## Ready for S-Record download ...
4281	~>examples/image.srec
4282	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
4283	...
4284	15989 15990 15991 15992
4285	[file transfer complete]
4286	[connected]
4287	## Start Addr = 0x00000000
4288
4289
4290You can check the success of the download using the 'iminfo' command;
4291this includes a checksum verification so you can be sure no data
4292corruption happened:
4293
4294	=> imi 40100000
4295
4296	## Checking Image at 40100000 ...
4297	   Image Name:	 2.2.13 for initrd on TQM850L
4298	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4299	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4300	   Load Address: 00000000
4301	   Entry Point:	 0000000c
4302	   Verifying Checksum ... OK
4303
4304
4305Boot Linux:
4306-----------
4307
4308The "bootm" command is used to boot an application that is stored in
4309memory (RAM or Flash). In case of a Linux kernel image, the contents
4310of the "bootargs" environment variable is passed to the kernel as
4311parameters. You can check and modify this variable using the
4312"printenv" and "setenv" commands:
4313
4314
4315	=> printenv bootargs
4316	bootargs=root=/dev/ram
4317
4318	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4319
4320	=> printenv bootargs
4321	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4322
4323	=> bootm 40020000
4324	## Booting Linux kernel at 40020000 ...
4325	   Image Name:	 2.2.13 for NFS on TQM850L
4326	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4327	   Data Size:	 381681 Bytes = 372 kB = 0 MB
4328	   Load Address: 00000000
4329	   Entry Point:	 0000000c
4330	   Verifying Checksum ... OK
4331	   Uncompressing Kernel Image ... OK
4332	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
4333	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4334	time_init: decrementer frequency = 187500000/60
4335	Calibrating delay loop... 49.77 BogoMIPS
4336	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
4337	...
4338
4339If you want to boot a Linux kernel with initial RAM disk, you pass
4340the memory addresses of both the kernel and the initrd image (PPBCOOT
4341format!) to the "bootm" command:
4342
4343	=> imi 40100000 40200000
4344
4345	## Checking Image at 40100000 ...
4346	   Image Name:	 2.2.13 for initrd on TQM850L
4347	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4348	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4349	   Load Address: 00000000
4350	   Entry Point:	 0000000c
4351	   Verifying Checksum ... OK
4352
4353	## Checking Image at 40200000 ...
4354	   Image Name:	 Simple Ramdisk Image
4355	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
4356	   Data Size:	 566530 Bytes = 553 kB = 0 MB
4357	   Load Address: 00000000
4358	   Entry Point:	 00000000
4359	   Verifying Checksum ... OK
4360
4361	=> bootm 40100000 40200000
4362	## Booting Linux kernel at 40100000 ...
4363	   Image Name:	 2.2.13 for initrd on TQM850L
4364	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4365	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4366	   Load Address: 00000000
4367	   Entry Point:	 0000000c
4368	   Verifying Checksum ... OK
4369	   Uncompressing Kernel Image ... OK
4370	## Loading RAMDisk Image at 40200000 ...
4371	   Image Name:	 Simple Ramdisk Image
4372	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
4373	   Data Size:	 566530 Bytes = 553 kB = 0 MB
4374	   Load Address: 00000000
4375	   Entry Point:	 00000000
4376	   Verifying Checksum ... OK
4377	   Loading Ramdisk ... OK
4378	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
4379	Boot arguments: root=/dev/ram
4380	time_init: decrementer frequency = 187500000/60
4381	Calibrating delay loop... 49.77 BogoMIPS
4382	...
4383	RAMDISK: Compressed image found at block 0
4384	VFS: Mounted root (ext2 filesystem).
4385
4386	bash#
4387
4388Boot Linux and pass a flat device tree:
4389-----------
4390
4391First, U-Boot must be compiled with the appropriate defines. See the section
4392titled "Linux Kernel Interface" above for a more in depth explanation. The
4393following is an example of how to start a kernel and pass an updated
4394flat device tree:
4395
4396=> print oftaddr
4397oftaddr=0x300000
4398=> print oft
4399oft=oftrees/mpc8540ads.dtb
4400=> tftp $oftaddr $oft
4401Speed: 1000, full duplex
4402Using TSEC0 device
4403TFTP from server 192.168.1.1; our IP address is 192.168.1.101
4404Filename 'oftrees/mpc8540ads.dtb'.
4405Load address: 0x300000
4406Loading: #
4407done
4408Bytes transferred = 4106 (100a hex)
4409=> tftp $loadaddr $bootfile
4410Speed: 1000, full duplex
4411Using TSEC0 device
4412TFTP from server 192.168.1.1; our IP address is 192.168.1.2
4413Filename 'uImage'.
4414Load address: 0x200000
4415Loading:############
4416done
4417Bytes transferred = 1029407 (fb51f hex)
4418=> print loadaddr
4419loadaddr=200000
4420=> print oftaddr
4421oftaddr=0x300000
4422=> bootm $loadaddr - $oftaddr
4423## Booting image at 00200000 ...
4424   Image Name:	 Linux-2.6.17-dirty
4425   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4426   Data Size:	 1029343 Bytes = 1005.2 kB
4427   Load Address: 00000000
4428   Entry Point:	 00000000
4429   Verifying Checksum ... OK
4430   Uncompressing Kernel Image ... OK
4431Booting using flat device tree at 0x300000
4432Using MPC85xx ADS machine description
4433Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
4434[snip]
4435
4436
4437More About U-Boot Image Types:
4438------------------------------
4439
4440U-Boot supports the following image types:
4441
4442   "Standalone Programs" are directly runnable in the environment
4443	provided by U-Boot; it is expected that (if they behave
4444	well) you can continue to work in U-Boot after return from
4445	the Standalone Program.
4446   "OS Kernel Images" are usually images of some Embedded OS which
4447	will take over control completely. Usually these programs
4448	will install their own set of exception handlers, device
4449	drivers, set up the MMU, etc. - this means, that you cannot
4450	expect to re-enter U-Boot except by resetting the CPU.
4451   "RAMDisk Images" are more or less just data blocks, and their
4452	parameters (address, size) are passed to an OS kernel that is
4453	being started.
4454   "Multi-File Images" contain several images, typically an OS
4455	(Linux) kernel image and one or more data images like
4456	RAMDisks. This construct is useful for instance when you want
4457	to boot over the network using BOOTP etc., where the boot
4458	server provides just a single image file, but you want to get
4459	for instance an OS kernel and a RAMDisk image.
4460
4461	"Multi-File Images" start with a list of image sizes, each
4462	image size (in bytes) specified by an "uint32_t" in network
4463	byte order. This list is terminated by an "(uint32_t)0".
4464	Immediately after the terminating 0 follow the images, one by
4465	one, all aligned on "uint32_t" boundaries (size rounded up to
4466	a multiple of 4 bytes).
4467
4468   "Firmware Images" are binary images containing firmware (like
4469	U-Boot or FPGA images) which usually will be programmed to
4470	flash memory.
4471
4472   "Script files" are command sequences that will be executed by
4473	U-Boot's command interpreter; this feature is especially
4474	useful when you configure U-Boot to use a real shell (hush)
4475	as command interpreter.
4476
4477Booting the Linux zImage:
4478-------------------------
4479
4480On some platforms, it's possible to boot Linux zImage. This is done
4481using the "bootz" command. The syntax of "bootz" command is the same
4482as the syntax of "bootm" command.
4483
4484Note, defining the CONFIG_SUPPORT_INITRD_RAW allows user to supply
4485kernel with raw initrd images. The syntax is slightly different, the
4486address of the initrd must be augmented by it's size, in the following
4487format: "<initrd addres>:<initrd size>".
4488
4489
4490Standalone HOWTO:
4491=================
4492
4493One of the features of U-Boot is that you can dynamically load and
4494run "standalone" applications, which can use some resources of
4495U-Boot like console I/O functions or interrupt services.
4496
4497Two simple examples are included with the sources:
4498
4499"Hello World" Demo:
4500-------------------
4501
4502'examples/hello_world.c' contains a small "Hello World" Demo
4503application; it is automatically compiled when you build U-Boot.
4504It's configured to run at address 0x00040004, so you can play with it
4505like that:
4506
4507	=> loads
4508	## Ready for S-Record download ...
4509	~>examples/hello_world.srec
4510	1 2 3 4 5 6 7 8 9 10 11 ...
4511	[file transfer complete]
4512	[connected]
4513	## Start Addr = 0x00040004
4514
4515	=> go 40004 Hello World! This is a test.
4516	## Starting application at 0x00040004 ...
4517	Hello World
4518	argc = 7
4519	argv[0] = "40004"
4520	argv[1] = "Hello"
4521	argv[2] = "World!"
4522	argv[3] = "This"
4523	argv[4] = "is"
4524	argv[5] = "a"
4525	argv[6] = "test."
4526	argv[7] = "<NULL>"
4527	Hit any key to exit ...
4528
4529	## Application terminated, rc = 0x0
4530
4531Another example, which demonstrates how to register a CPM interrupt
4532handler with the U-Boot code, can be found in 'examples/timer.c'.
4533Here, a CPM timer is set up to generate an interrupt every second.
4534The interrupt service routine is trivial, just printing a '.'
4535character, but this is just a demo program. The application can be
4536controlled by the following keys:
4537
4538	? - print current values og the CPM Timer registers
4539	b - enable interrupts and start timer
4540	e - stop timer and disable interrupts
4541	q - quit application
4542
4543	=> loads
4544	## Ready for S-Record download ...
4545	~>examples/timer.srec
4546	1 2 3 4 5 6 7 8 9 10 11 ...
4547	[file transfer complete]
4548	[connected]
4549	## Start Addr = 0x00040004
4550
4551	=> go 40004
4552	## Starting application at 0x00040004 ...
4553	TIMERS=0xfff00980
4554	Using timer 1
4555	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
4556
4557Hit 'b':
4558	[q, b, e, ?] Set interval 1000000 us
4559	Enabling timer
4560Hit '?':
4561	[q, b, e, ?] ........
4562	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
4563Hit '?':
4564	[q, b, e, ?] .
4565	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
4566Hit '?':
4567	[q, b, e, ?] .
4568	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
4569Hit '?':
4570	[q, b, e, ?] .
4571	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
4572Hit 'e':
4573	[q, b, e, ?] ...Stopping timer
4574Hit 'q':
4575	[q, b, e, ?] ## Application terminated, rc = 0x0
4576
4577
4578Minicom warning:
4579================
4580
4581Over time, many people have reported problems when trying to use the
4582"minicom" terminal emulation program for serial download. I (wd)
4583consider minicom to be broken, and recommend not to use it. Under
4584Unix, I recommend to use C-Kermit for general purpose use (and
4585especially for kermit binary protocol download ("loadb" command), and
4586use "cu" for S-Record download ("loads" command).
4587
4588Nevertheless, if you absolutely want to use it try adding this
4589configuration to your "File transfer protocols" section:
4590
4591	   Name	   Program			Name U/D FullScr IO-Red. Multi
4592	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
4593	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
4594
4595
4596NetBSD Notes:
4597=============
4598
4599Starting at version 0.9.2, U-Boot supports NetBSD both as host
4600(build U-Boot) and target system (boots NetBSD/mpc8xx).
4601
4602Building requires a cross environment; it is known to work on
4603NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
4604need gmake since the Makefiles are not compatible with BSD make).
4605Note that the cross-powerpc package does not install include files;
4606attempting to build U-Boot will fail because <machine/ansi.h> is
4607missing.  This file has to be installed and patched manually:
4608
4609	# cd /usr/pkg/cross/powerpc-netbsd/include
4610	# mkdir powerpc
4611	# ln -s powerpc machine
4612	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
4613	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
4614
4615Native builds *don't* work due to incompatibilities between native
4616and U-Boot include files.
4617
4618Booting assumes that (the first part of) the image booted is a
4619stage-2 loader which in turn loads and then invokes the kernel
4620proper. Loader sources will eventually appear in the NetBSD source
4621tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
4622meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
4623
4624
4625Implementation Internals:
4626=========================
4627
4628The following is not intended to be a complete description of every
4629implementation detail. However, it should help to understand the
4630inner workings of U-Boot and make it easier to port it to custom
4631hardware.
4632
4633
4634Initial Stack, Global Data:
4635---------------------------
4636
4637The implementation of U-Boot is complicated by the fact that U-Boot
4638starts running out of ROM (flash memory), usually without access to
4639system RAM (because the memory controller is not initialized yet).
4640This means that we don't have writable Data or BSS segments, and BSS
4641is not initialized as zero. To be able to get a C environment working
4642at all, we have to allocate at least a minimal stack. Implementation
4643options for this are defined and restricted by the CPU used: Some CPU
4644models provide on-chip memory (like the IMMR area on MPC8xx and
4645MPC826x processors), on others (parts of) the data cache can be
4646locked as (mis-) used as memory, etc.
4647
4648	Chris Hallinan posted a good summary of these issues to the
4649	U-Boot mailing list:
4650
4651	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
4652	From: "Chris Hallinan" <clh@net1plus.com>
4653	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
4654	...
4655
4656	Correct me if I'm wrong, folks, but the way I understand it
4657	is this: Using DCACHE as initial RAM for Stack, etc, does not
4658	require any physical RAM backing up the cache. The cleverness
4659	is that the cache is being used as a temporary supply of
4660	necessary storage before the SDRAM controller is setup. It's
4661	beyond the scope of this list to explain the details, but you
4662	can see how this works by studying the cache architecture and
4663	operation in the architecture and processor-specific manuals.
4664
4665	OCM is On Chip Memory, which I believe the 405GP has 4K. It
4666	is another option for the system designer to use as an
4667	initial stack/RAM area prior to SDRAM being available. Either
4668	option should work for you. Using CS 4 should be fine if your
4669	board designers haven't used it for something that would
4670	cause you grief during the initial boot! It is frequently not
4671	used.
4672
4673	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
4674	with your processor/board/system design. The default value
4675	you will find in any recent u-boot distribution in
4676	walnut.h should work for you. I'd set it to a value larger
4677	than your SDRAM module. If you have a 64MB SDRAM module, set
4678	it above 400_0000. Just make sure your board has no resources
4679	that are supposed to respond to that address! That code in
4680	start.S has been around a while and should work as is when
4681	you get the config right.
4682
4683	-Chris Hallinan
4684	DS4.COM, Inc.
4685
4686It is essential to remember this, since it has some impact on the C
4687code for the initialization procedures:
4688
4689* Initialized global data (data segment) is read-only. Do not attempt
4690  to write it.
4691
4692* Do not use any uninitialized global data (or implicitely initialized
4693  as zero data - BSS segment) at all - this is undefined, initiali-
4694  zation is performed later (when relocating to RAM).
4695
4696* Stack space is very limited. Avoid big data buffers or things like
4697  that.
4698
4699Having only the stack as writable memory limits means we cannot use
4700normal global data to share information beween the code. But it
4701turned out that the implementation of U-Boot can be greatly
4702simplified by making a global data structure (gd_t) available to all
4703functions. We could pass a pointer to this data as argument to _all_
4704functions, but this would bloat the code. Instead we use a feature of
4705the GCC compiler (Global Register Variables) to share the data: we
4706place a pointer (gd) to the global data into a register which we
4707reserve for this purpose.
4708
4709When choosing a register for such a purpose we are restricted by the
4710relevant  (E)ABI  specifications for the current architecture, and by
4711GCC's implementation.
4712
4713For PowerPC, the following registers have specific use:
4714	R1:	stack pointer
4715	R2:	reserved for system use
4716	R3-R4:	parameter passing and return values
4717	R5-R10: parameter passing
4718	R13:	small data area pointer
4719	R30:	GOT pointer
4720	R31:	frame pointer
4721
4722	(U-Boot also uses R12 as internal GOT pointer. r12
4723	is a volatile register so r12 needs to be reset when
4724	going back and forth between asm and C)
4725
4726    ==> U-Boot will use R2 to hold a pointer to the global data
4727
4728    Note: on PPC, we could use a static initializer (since the
4729    address of the global data structure is known at compile time),
4730    but it turned out that reserving a register results in somewhat
4731    smaller code - although the code savings are not that big (on
4732    average for all boards 752 bytes for the whole U-Boot image,
4733    624 text + 127 data).
4734
4735On Blackfin, the normal C ABI (except for P3) is followed as documented here:
4736	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
4737
4738    ==> U-Boot will use P3 to hold a pointer to the global data
4739
4740On ARM, the following registers are used:
4741
4742	R0:	function argument word/integer result
4743	R1-R3:	function argument word
4744	R9:	GOT pointer
4745	R10:	stack limit (used only if stack checking if enabled)
4746	R11:	argument (frame) pointer
4747	R12:	temporary workspace
4748	R13:	stack pointer
4749	R14:	link register
4750	R15:	program counter
4751
4752    ==> U-Boot will use R8 to hold a pointer to the global data
4753
4754On Nios II, the ABI is documented here:
4755	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
4756
4757    ==> U-Boot will use gp to hold a pointer to the global data
4758
4759    Note: on Nios II, we give "-G0" option to gcc and don't use gp
4760    to access small data sections, so gp is free.
4761
4762On NDS32, the following registers are used:
4763
4764	R0-R1:	argument/return
4765	R2-R5:	argument
4766	R15:	temporary register for assembler
4767	R16:	trampoline register
4768	R28:	frame pointer (FP)
4769	R29:	global pointer (GP)
4770	R30:	link register (LP)
4771	R31:	stack pointer (SP)
4772	PC:	program counter (PC)
4773
4774    ==> U-Boot will use R10 to hold a pointer to the global data
4775
4776NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
4777or current versions of GCC may "optimize" the code too much.
4778
4779Memory Management:
4780------------------
4781
4782U-Boot runs in system state and uses physical addresses, i.e. the
4783MMU is not used either for address mapping nor for memory protection.
4784
4785The available memory is mapped to fixed addresses using the memory
4786controller. In this process, a contiguous block is formed for each
4787memory type (Flash, SDRAM, SRAM), even when it consists of several
4788physical memory banks.
4789
4790U-Boot is installed in the first 128 kB of the first Flash bank (on
4791TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
4792booting and sizing and initializing DRAM, the code relocates itself
4793to the upper end of DRAM. Immediately below the U-Boot code some
4794memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
4795configuration setting]. Below that, a structure with global Board
4796Info data is placed, followed by the stack (growing downward).
4797
4798Additionally, some exception handler code is copied to the low 8 kB
4799of DRAM (0x00000000 ... 0x00001FFF).
4800
4801So a typical memory configuration with 16 MB of DRAM could look like
4802this:
4803
4804	0x0000 0000	Exception Vector code
4805	      :
4806	0x0000 1FFF
4807	0x0000 2000	Free for Application Use
4808	      :
4809	      :
4810
4811	      :
4812	      :
4813	0x00FB FF20	Monitor Stack (Growing downward)
4814	0x00FB FFAC	Board Info Data and permanent copy of global data
4815	0x00FC 0000	Malloc Arena
4816	      :
4817	0x00FD FFFF
4818	0x00FE 0000	RAM Copy of Monitor Code
4819	...		eventually: LCD or video framebuffer
4820	...		eventually: pRAM (Protected RAM - unchanged by reset)
4821	0x00FF FFFF	[End of RAM]
4822
4823
4824System Initialization:
4825----------------------
4826
4827In the reset configuration, U-Boot starts at the reset entry point
4828(on most PowerPC systems at address 0x00000100). Because of the reset
4829configuration for CS0# this is a mirror of the onboard Flash memory.
4830To be able to re-map memory U-Boot then jumps to its link address.
4831To be able to implement the initialization code in C, a (small!)
4832initial stack is set up in the internal Dual Ported RAM (in case CPUs
4833which provide such a feature like MPC8xx or MPC8260), or in a locked
4834part of the data cache. After that, U-Boot initializes the CPU core,
4835the caches and the SIU.
4836
4837Next, all (potentially) available memory banks are mapped using a
4838preliminary mapping. For example, we put them on 512 MB boundaries
4839(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
4840on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
4841programmed for SDRAM access. Using the temporary configuration, a
4842simple memory test is run that determines the size of the SDRAM
4843banks.
4844
4845When there is more than one SDRAM bank, and the banks are of
4846different size, the largest is mapped first. For equal size, the first
4847bank (CS2#) is mapped first. The first mapping is always for address
48480x00000000, with any additional banks following immediately to create
4849contiguous memory starting from 0.
4850
4851Then, the monitor installs itself at the upper end of the SDRAM area
4852and allocates memory for use by malloc() and for the global Board
4853Info data; also, the exception vector code is copied to the low RAM
4854pages, and the final stack is set up.
4855
4856Only after this relocation will you have a "normal" C environment;
4857until that you are restricted in several ways, mostly because you are
4858running from ROM, and because the code will have to be relocated to a
4859new address in RAM.
4860
4861
4862U-Boot Porting Guide:
4863----------------------
4864
4865[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
4866list, October 2002]
4867
4868
4869int main(int argc, char *argv[])
4870{
4871	sighandler_t no_more_time;
4872
4873	signal(SIGALRM, no_more_time);
4874	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
4875
4876	if (available_money > available_manpower) {
4877		Pay consultant to port U-Boot;
4878		return 0;
4879	}
4880
4881	Download latest U-Boot source;
4882
4883	Subscribe to u-boot mailing list;
4884
4885	if (clueless)
4886		email("Hi, I am new to U-Boot, how do I get started?");
4887
4888	while (learning) {
4889		Read the README file in the top level directory;
4890		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
4891		Read applicable doc/*.README;
4892		Read the source, Luke;
4893		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
4894	}
4895
4896	if (available_money > toLocalCurrency ($2500))
4897		Buy a BDI3000;
4898	else
4899		Add a lot of aggravation and time;
4900
4901	if (a similar board exists) {	/* hopefully... */
4902		cp -a board/<similar> board/<myboard>
4903		cp include/configs/<similar>.h include/configs/<myboard>.h
4904	} else {
4905		Create your own board support subdirectory;
4906		Create your own board include/configs/<myboard>.h file;
4907	}
4908	Edit new board/<myboard> files
4909	Edit new include/configs/<myboard>.h
4910
4911	while (!accepted) {
4912		while (!running) {
4913			do {
4914				Add / modify source code;
4915			} until (compiles);
4916			Debug;
4917			if (clueless)
4918				email("Hi, I am having problems...");
4919		}
4920		Send patch file to the U-Boot email list;
4921		if (reasonable critiques)
4922			Incorporate improvements from email list code review;
4923		else
4924			Defend code as written;
4925	}
4926
4927	return 0;
4928}
4929
4930void no_more_time (int sig)
4931{
4932      hire_a_guru();
4933}
4934
4935
4936Coding Standards:
4937-----------------
4938
4939All contributions to U-Boot should conform to the Linux kernel
4940coding style; see the file "Documentation/CodingStyle" and the script
4941"scripts/Lindent" in your Linux kernel source directory.
4942
4943Source files originating from a different project (for example the
4944MTD subsystem) are generally exempt from these guidelines and are not
4945reformated to ease subsequent migration to newer versions of those
4946sources.
4947
4948Please note that U-Boot is implemented in C (and to some small parts in
4949Assembler); no C++ is used, so please do not use C++ style comments (//)
4950in your code.
4951
4952Please also stick to the following formatting rules:
4953- remove any trailing white space
4954- use TAB characters for indentation and vertical alignment, not spaces
4955- make sure NOT to use DOS '\r\n' line feeds
4956- do not add more than 2 consecutive empty lines to source files
4957- do not add trailing empty lines to source files
4958
4959Submissions which do not conform to the standards may be returned
4960with a request to reformat the changes.
4961
4962
4963Submitting Patches:
4964-------------------
4965
4966Since the number of patches for U-Boot is growing, we need to
4967establish some rules. Submissions which do not conform to these rules
4968may be rejected, even when they contain important and valuable stuff.
4969
4970Please see http://www.denx.de/wiki/U-Boot/Patches for details.
4971
4972Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
4973see http://lists.denx.de/mailman/listinfo/u-boot
4974
4975When you send a patch, please include the following information with
4976it:
4977
4978* For bug fixes: a description of the bug and how your patch fixes
4979  this bug. Please try to include a way of demonstrating that the
4980  patch actually fixes something.
4981
4982* For new features: a description of the feature and your
4983  implementation.
4984
4985* A CHANGELOG entry as plaintext (separate from the patch)
4986
4987* For major contributions, your entry to the CREDITS file
4988
4989* When you add support for a new board, don't forget to add this
4990  board to the MAINTAINERS file, too.
4991
4992* If your patch adds new configuration options, don't forget to
4993  document these in the README file.
4994
4995* The patch itself. If you are using git (which is *strongly*
4996  recommended) you can easily generate the patch using the
4997  "git format-patch". If you then use "git send-email" to send it to
4998  the U-Boot mailing list, you will avoid most of the common problems
4999  with some other mail clients.
5000
5001  If you cannot use git, use "diff -purN OLD NEW". If your version of
5002  diff does not support these options, then get the latest version of
5003  GNU diff.
5004
5005  The current directory when running this command shall be the parent
5006  directory of the U-Boot source tree (i. e. please make sure that
5007  your patch includes sufficient directory information for the
5008  affected files).
5009
5010  We prefer patches as plain text. MIME attachments are discouraged,
5011  and compressed attachments must not be used.
5012
5013* If one logical set of modifications affects or creates several
5014  files, all these changes shall be submitted in a SINGLE patch file.
5015
5016* Changesets that contain different, unrelated modifications shall be
5017  submitted as SEPARATE patches, one patch per changeset.
5018
5019
5020Notes:
5021
5022* Before sending the patch, run the MAKEALL script on your patched
5023  source tree and make sure that no errors or warnings are reported
5024  for any of the boards.
5025
5026* Keep your modifications to the necessary minimum: A patch
5027  containing several unrelated changes or arbitrary reformats will be
5028  returned with a request to re-formatting / split it.
5029
5030* If you modify existing code, make sure that your new code does not
5031  add to the memory footprint of the code ;-) Small is beautiful!
5032  When adding new features, these should compile conditionally only
5033  (using #ifdef), and the resulting code with the new feature
5034  disabled must not need more memory than the old code without your
5035  modification.
5036
5037* Remember that there is a size limit of 100 kB per message on the
5038  u-boot mailing list. Bigger patches will be moderated. If they are
5039  reasonable and not too big, they will be acknowledged. But patches
5040  bigger than the size limit should be avoided.
5041