xref: /openbmc/u-boot/README (revision 62c3ae7c)
1#
2# (C) Copyright 2000 - 2008
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
129U-Boot uses a 3 level version number containing a version, a
130sub-version, and a patchlevel: "U-Boot-2.34.5" means version "2",
131sub-version "34", and patchlevel "4".
132
133The patchlevel is used to indicate certain stages of development
134between released versions, i. e. officially released versions of
135U-Boot will always have a patchlevel of "0".
136
137
138Directory Hierarchy:
139====================
140
141- board		Board dependent files
142- common	Misc architecture independent functions
143- cpu		CPU specific files
144  - 74xx_7xx	Files specific to Freescale MPC74xx and 7xx CPUs
145  - arm720t	Files specific to ARM 720 CPUs
146  - arm920t	Files specific to ARM 920 CPUs
147    - at91rm9200 Files specific to Atmel AT91RM9200 CPU
148    - imx	Files specific to Freescale MC9328 i.MX CPUs
149    - s3c24x0	Files specific to Samsung S3C24X0 CPUs
150  - arm925t	Files specific to ARM 925 CPUs
151  - arm926ejs	Files specific to ARM 926 CPUs
152  - arm1136	Files specific to ARM 1136 CPUs
153  - at32ap	Files specific to Atmel AVR32 AP CPUs
154  - blackfin	Files specific to Analog Devices Blackfin CPUs
155  - i386	Files specific to i386 CPUs
156  - ixp		Files specific to Intel XScale IXP CPUs
157  - leon2	Files specific to Gaisler LEON2 SPARC CPU
158  - leon3	Files specific to Gaisler LEON3 SPARC CPU
159  - mcf52x2	Files specific to Freescale ColdFire MCF52x2 CPUs
160  - mcf5227x	Files specific to Freescale ColdFire MCF5227x CPUs
161  - mcf532x	Files specific to Freescale ColdFire MCF5329 CPUs
162  - mcf5445x	Files specific to Freescale ColdFire MCF5445x CPUs
163  - mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
164  - mips	Files specific to MIPS CPUs
165  - mpc5xx	Files specific to Freescale MPC5xx  CPUs
166  - mpc5xxx	Files specific to Freescale MPC5xxx CPUs
167  - mpc8xx	Files specific to Freescale MPC8xx  CPUs
168  - mpc8220	Files specific to Freescale MPC8220 CPUs
169  - mpc824x	Files specific to Freescale MPC824x CPUs
170  - mpc8260	Files specific to Freescale MPC8260 CPUs
171  - mpc85xx	Files specific to Freescale MPC85xx CPUs
172  - nios	Files specific to Altera NIOS CPUs
173  - nios2	Files specific to Altera Nios-II CPUs
174  - ppc4xx	Files specific to AMCC PowerPC 4xx CPUs
175  - pxa		Files specific to Intel XScale PXA CPUs
176  - s3c44b0	Files specific to Samsung S3C44B0 CPUs
177  - sa1100	Files specific to Intel StrongARM SA1100 CPUs
178- disk		Code for disk drive partition handling
179- doc		Documentation (don't expect too much)
180- drivers	Commonly used device drivers
181- dtt		Digital Thermometer and Thermostat drivers
182- examples	Example code for standalone applications, etc.
183- include	Header Files
184- lib_arm	Files generic to ARM	 architecture
185- lib_avr32	Files generic to AVR32	 architecture
186- lib_blackfin	Files generic to Blackfin architecture
187- lib_generic	Files generic to all	 architectures
188- lib_i386	Files generic to i386	 architecture
189- lib_m68k	Files generic to m68k	 architecture
190- lib_mips	Files generic to MIPS	 architecture
191- lib_nios	Files generic to NIOS	 architecture
192- lib_ppc	Files generic to PowerPC architecture
193- lib_sparc	Files generic to SPARC	 architecture
194- libfdt	Library files to support flattened device trees
195- net		Networking code
196- post		Power On Self Test
197- rtc		Real Time Clock drivers
198- tools		Tools to build S-Record or U-Boot images, etc.
199
200Software Configuration:
201=======================
202
203Configuration is usually done using C preprocessor defines; the
204rationale behind that is to avoid dead code whenever possible.
205
206There are two classes of configuration variables:
207
208* Configuration _OPTIONS_:
209  These are selectable by the user and have names beginning with
210  "CONFIG_".
211
212* Configuration _SETTINGS_:
213  These depend on the hardware etc. and should not be meddled with if
214  you don't know what you're doing; they have names beginning with
215  "CONFIG_SYS_".
216
217Later we will add a configuration tool - probably similar to or even
218identical to what's used for the Linux kernel. Right now, we have to
219do the configuration by hand, which means creating some symbolic
220links and editing some configuration files. We use the TQM8xxL boards
221as an example here.
222
223
224Selection of Processor Architecture and Board Type:
225---------------------------------------------------
226
227For all supported boards there are ready-to-use default
228configurations available; just type "make <board_name>_config".
229
230Example: For a TQM823L module type:
231
232	cd u-boot
233	make TQM823L_config
234
235For the Cogent platform, you need to specify the CPU type as well;
236e.g. "make cogent_mpc8xx_config". And also configure the cogent
237directory according to the instructions in cogent/README.
238
239
240Configuration Options:
241----------------------
242
243Configuration depends on the combination of board and CPU type; all
244such information is kept in a configuration file
245"include/configs/<board_name>.h".
246
247Example: For a TQM823L module, all configuration settings are in
248"include/configs/TQM823L.h".
249
250
251Many of the options are named exactly as the corresponding Linux
252kernel configuration options. The intention is to make it easier to
253build a config tool - later.
254
255
256The following options need to be configured:
257
258- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
259
260- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
261
262- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
263		Define exactly one, e.g. CONFIG_ATSTK1002
264
265- CPU Module Type: (if CONFIG_COGENT is defined)
266		Define exactly one of
267		CONFIG_CMA286_60_OLD
268--- FIXME --- not tested yet:
269		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
270		CONFIG_CMA287_23, CONFIG_CMA287_50
271
272- Motherboard Type: (if CONFIG_COGENT is defined)
273		Define exactly one of
274		CONFIG_CMA101, CONFIG_CMA102
275
276- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
277		Define one or more of
278		CONFIG_CMA302
279
280- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
281		Define one or more of
282		CONFIG_LCD_HEARTBEAT	- update a character position on
283					  the LCD display every second with
284					  a "rotator" |\-/|\-/
285
286- Board flavour: (if CONFIG_MPC8260ADS is defined)
287		CONFIG_ADSTYPE
288		Possible values are:
289			CONFIG_SYS_8260ADS	- original MPC8260ADS
290			CONFIG_SYS_8266ADS	- MPC8266ADS
291			CONFIG_SYS_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
292			CONFIG_SYS_8272ADS	- MPC8272ADS
293
294- MPC824X Family Member (if CONFIG_MPC824X is defined)
295		Define exactly one of
296		CONFIG_MPC8240, CONFIG_MPC8245
297
298- 8xx CPU Options: (if using an MPC8xx CPU)
299		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
300					  get_gclk_freq() cannot work
301					  e.g. if there is no 32KHz
302					  reference PIT/RTC clock
303		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
304					  or XTAL/EXTAL)
305
306- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
307		CONFIG_SYS_8xx_CPUCLK_MIN
308		CONFIG_SYS_8xx_CPUCLK_MAX
309		CONFIG_8xx_CPUCLK_DEFAULT
310			See doc/README.MPC866
311
312		CONFIG_SYS_MEASURE_CPUCLK
313
314		Define this to measure the actual CPU clock instead
315		of relying on the correctness of the configured
316		values. Mostly useful for board bringup to make sure
317		the PLL is locked at the intended frequency. Note
318		that this requires a (stable) reference clock (32 kHz
319		RTC clock or CONFIG_SYS_8XX_XIN)
320
321- Intel Monahans options:
322		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
323
324		Defines the Monahans run mode to oscillator
325		ratio. Valid values are 8, 16, 24, 31. The core
326		frequency is this value multiplied by 13 MHz.
327
328		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
329
330		Defines the Monahans turbo mode to oscillator
331		ratio. Valid values are 1 (default if undefined) and
332		2. The core frequency as calculated above is multiplied
333		by this value.
334
335- Linux Kernel Interface:
336		CONFIG_CLOCKS_IN_MHZ
337
338		U-Boot stores all clock information in Hz
339		internally. For binary compatibility with older Linux
340		kernels (which expect the clocks passed in the
341		bd_info data to be in MHz) the environment variable
342		"clocks_in_mhz" can be defined so that U-Boot
343		converts clock data to MHZ before passing it to the
344		Linux kernel.
345		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
346		"clocks_in_mhz=1" is automatically included in the
347		default environment.
348
349		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
350
351		When transferring memsize parameter to linux, some versions
352		expect it to be in bytes, others in MB.
353		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
354
355		CONFIG_OF_LIBFDT
356
357		New kernel versions are expecting firmware settings to be
358		passed using flattened device trees (based on open firmware
359		concepts).
360
361		CONFIG_OF_LIBFDT
362		 * New libfdt-based support
363		 * Adds the "fdt" command
364		 * The bootm command automatically updates the fdt
365
366		OF_CPU - The proper name of the cpus node.
367		OF_SOC - The proper name of the soc node.
368		OF_TBCLK - The timebase frequency.
369		OF_STDOUT_PATH - The path to the console device
370
371		boards with QUICC Engines require OF_QE to set UCC MAC
372		addresses
373
374		CONFIG_OF_BOARD_SETUP
375
376		Board code has addition modification that it wants to make
377		to the flat device tree before handing it off to the kernel
378
379		CONFIG_OF_BOOT_CPU
380
381		This define fills in the correct boot CPU in the boot
382		param header, the default value is zero if undefined.
383
384- vxWorks boot parameters:
385
386		bootvx constructs a valid bootline using the following
387		environments variables: bootfile, ipaddr, serverip, hostname.
388		It loads the vxWorks image pointed bootfile.
389
390		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
391		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
392		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
393		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
394
395		CONFIG_SYS_VXWORKS_ADD_PARAMS
396
397		Add it at the end of the bootline. E.g "u=username pw=secret"
398
399		Note: If a "bootargs" environment is defined, it will overwride
400		the defaults discussed just above.
401
402- Serial Ports:
403		CONFIG_PL010_SERIAL
404
405		Define this if you want support for Amba PrimeCell PL010 UARTs.
406
407		CONFIG_PL011_SERIAL
408
409		Define this if you want support for Amba PrimeCell PL011 UARTs.
410
411		CONFIG_PL011_CLOCK
412
413		If you have Amba PrimeCell PL011 UARTs, set this variable to
414		the clock speed of the UARTs.
415
416		CONFIG_PL01x_PORTS
417
418		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
419		define this to a list of base addresses for each (supported)
420		port. See e.g. include/configs/versatile.h
421
422
423- Console Interface:
424		Depending on board, define exactly one serial port
425		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
426		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
427		console by defining CONFIG_8xx_CONS_NONE
428
429		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
430		port routines must be defined elsewhere
431		(i.e. serial_init(), serial_getc(), ...)
432
433		CONFIG_CFB_CONSOLE
434		Enables console device for a color framebuffer. Needs following
435		defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
436			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
437						(default big endian)
438			VIDEO_HW_RECTFILL	graphic chip supports
439						rectangle fill
440						(cf. smiLynxEM)
441			VIDEO_HW_BITBLT		graphic chip supports
442						bit-blit (cf. smiLynxEM)
443			VIDEO_VISIBLE_COLS	visible pixel columns
444						(cols=pitch)
445			VIDEO_VISIBLE_ROWS	visible pixel rows
446			VIDEO_PIXEL_SIZE	bytes per pixel
447			VIDEO_DATA_FORMAT	graphic data format
448						(0-5, cf. cfb_console.c)
449			VIDEO_FB_ADRS		framebuffer address
450			VIDEO_KBD_INIT_FCT	keyboard int fct
451						(i.e. i8042_kbd_init())
452			VIDEO_TSTC_FCT		test char fct
453						(i.e. i8042_tstc)
454			VIDEO_GETC_FCT		get char fct
455						(i.e. i8042_getc)
456			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
457						(requires blink timer
458						cf. i8042.c)
459			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
460			CONFIG_CONSOLE_TIME	display time/date info in
461						upper right corner
462						(requires CONFIG_CMD_DATE)
463			CONFIG_VIDEO_LOGO	display Linux logo in
464						upper left corner
465			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
466						linux_logo.h for logo.
467						Requires CONFIG_VIDEO_LOGO
468			CONFIG_CONSOLE_EXTRA_INFO
469						additional board info beside
470						the logo
471
472		When CONFIG_CFB_CONSOLE is defined, video console is
473		default i/o. Serial console can be forced with
474		environment 'console=serial'.
475
476		When CONFIG_SILENT_CONSOLE is defined, all console
477		messages (by U-Boot and Linux!) can be silenced with
478		the "silent" environment variable. See
479		doc/README.silent for more information.
480
481- Console Baudrate:
482		CONFIG_BAUDRATE - in bps
483		Select one of the baudrates listed in
484		CONFIG_SYS_BAUDRATE_TABLE, see below.
485		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
486
487- Interrupt driven serial port input:
488		CONFIG_SERIAL_SOFTWARE_FIFO
489
490		PPC405GP only.
491		Use an interrupt handler for receiving data on the
492		serial port. It also enables using hardware handshake
493		(RTS/CTS) and UART's built-in FIFO. Set the number of
494		bytes the interrupt driven input buffer should have.
495
496		Leave undefined to disable this feature, including
497		disable the buffer and hardware handshake.
498
499- Console UART Number:
500		CONFIG_UART1_CONSOLE
501
502		AMCC PPC4xx only.
503		If defined internal UART1 (and not UART0) is used
504		as default U-Boot console.
505
506- Boot Delay:	CONFIG_BOOTDELAY - in seconds
507		Delay before automatically booting the default image;
508		set to -1 to disable autoboot.
509
510		See doc/README.autoboot for these options that
511		work with CONFIG_BOOTDELAY. None are required.
512		CONFIG_BOOT_RETRY_TIME
513		CONFIG_BOOT_RETRY_MIN
514		CONFIG_AUTOBOOT_KEYED
515		CONFIG_AUTOBOOT_PROMPT
516		CONFIG_AUTOBOOT_DELAY_STR
517		CONFIG_AUTOBOOT_STOP_STR
518		CONFIG_AUTOBOOT_DELAY_STR2
519		CONFIG_AUTOBOOT_STOP_STR2
520		CONFIG_ZERO_BOOTDELAY_CHECK
521		CONFIG_RESET_TO_RETRY
522
523- Autoboot Command:
524		CONFIG_BOOTCOMMAND
525		Only needed when CONFIG_BOOTDELAY is enabled;
526		define a command string that is automatically executed
527		when no character is read on the console interface
528		within "Boot Delay" after reset.
529
530		CONFIG_BOOTARGS
531		This can be used to pass arguments to the bootm
532		command. The value of CONFIG_BOOTARGS goes into the
533		environment value "bootargs".
534
535		CONFIG_RAMBOOT and CONFIG_NFSBOOT
536		The value of these goes into the environment as
537		"ramboot" and "nfsboot" respectively, and can be used
538		as a convenience, when switching between booting from
539		RAM and NFS.
540
541- Pre-Boot Commands:
542		CONFIG_PREBOOT
543
544		When this option is #defined, the existence of the
545		environment variable "preboot" will be checked
546		immediately before starting the CONFIG_BOOTDELAY
547		countdown and/or running the auto-boot command resp.
548		entering interactive mode.
549
550		This feature is especially useful when "preboot" is
551		automatically generated or modified. For an example
552		see the LWMON board specific code: here "preboot" is
553		modified when the user holds down a certain
554		combination of keys on the (special) keyboard when
555		booting the systems
556
557- Serial Download Echo Mode:
558		CONFIG_LOADS_ECHO
559		If defined to 1, all characters received during a
560		serial download (using the "loads" command) are
561		echoed back. This might be needed by some terminal
562		emulations (like "cu"), but may as well just take
563		time on others. This setting #define's the initial
564		value of the "loads_echo" environment variable.
565
566- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
567		CONFIG_KGDB_BAUDRATE
568		Select one of the baudrates listed in
569		CONFIG_SYS_BAUDRATE_TABLE, see below.
570
571- Monitor Functions:
572		Monitor commands can be included or excluded
573		from the build by using the #include files
574		"config_cmd_all.h" and #undef'ing unwanted
575		commands, or using "config_cmd_default.h"
576		and augmenting with additional #define's
577		for wanted commands.
578
579		The default command configuration includes all commands
580		except those marked below with a "*".
581
582		CONFIG_CMD_ASKENV	* ask for env variable
583		CONFIG_CMD_AUTOSCRIPT	  Autoscript Support
584		CONFIG_CMD_BDI		  bdinfo
585		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
586		CONFIG_CMD_BMP		* BMP support
587		CONFIG_CMD_BSP		* Board specific commands
588		CONFIG_CMD_BOOTD	  bootd
589		CONFIG_CMD_CACHE	* icache, dcache
590		CONFIG_CMD_CONSOLE	  coninfo
591		CONFIG_CMD_DATE		* support for RTC, date/time...
592		CONFIG_CMD_DHCP		* DHCP support
593		CONFIG_CMD_DIAG		* Diagnostics
594		CONFIG_CMD_DOC		* Disk-On-Chip Support
595		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
596		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
597		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
598		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
599		CONFIG_CMD_DTT		* Digital Therm and Thermostat
600		CONFIG_CMD_ECHO		  echo arguments
601		CONFIG_CMD_EEPROM	* EEPROM read/write support
602		CONFIG_CMD_ELF		* bootelf, bootvx
603		CONFIG_CMD_ENV		  saveenv
604		CONFIG_CMD_FDC		* Floppy Disk Support
605		CONFIG_CMD_FAT		* FAT partition support
606		CONFIG_CMD_FDOS		* Dos diskette Support
607		CONFIG_CMD_FLASH	  flinfo, erase, protect
608		CONFIG_CMD_FPGA		  FPGA device initialization support
609		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
610		CONFIG_CMD_I2C		* I2C serial bus support
611		CONFIG_CMD_IDE		* IDE harddisk support
612		CONFIG_CMD_IMI		  iminfo
613		CONFIG_CMD_IMLS		  List all found images
614		CONFIG_CMD_IMMAP	* IMMR dump support
615		CONFIG_CMD_IRQ		* irqinfo
616		CONFIG_CMD_ITEST	  Integer/string test of 2 values
617		CONFIG_CMD_JFFS2	* JFFS2 Support
618		CONFIG_CMD_KGDB		* kgdb
619		CONFIG_CMD_LOADB	  loadb
620		CONFIG_CMD_LOADS	  loads
621		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
622					  loop, loopw, mtest
623		CONFIG_CMD_MISC		  Misc functions like sleep etc
624		CONFIG_CMD_MMC		* MMC memory mapped support
625		CONFIG_CMD_MII		* MII utility commands
626		CONFIG_CMD_NAND		* NAND support
627		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
628		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
629		CONFIG_CMD_PCA953X_INFO	* PCA953x I2C gpio info command
630		CONFIG_CMD_PCI		* pciinfo
631		CONFIG_CMD_PCMCIA		* PCMCIA support
632		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
633					  host
634		CONFIG_CMD_PORTIO	* Port I/O
635		CONFIG_CMD_REGINFO	* Register dump
636		CONFIG_CMD_RUN		  run command in env variable
637		CONFIG_CMD_SAVES	* save S record dump
638		CONFIG_CMD_SCSI		* SCSI Support
639		CONFIG_CMD_SDRAM	* print SDRAM configuration information
640					  (requires CONFIG_CMD_I2C)
641		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
642					  (4xx only)
643		CONFIG_CMD_SPI		* SPI serial bus support
644		CONFIG_CMD_USB		* USB support
645		CONFIG_CMD_VFD		* VFD support (TRAB)
646		CONFIG_CMD_CDP		* Cisco Discover Protocol support
647		CONFIG_CMD_FSL		* Microblaze FSL support
648
649
650		EXAMPLE: If you want all functions except of network
651		support you can write:
652
653		#include "config_cmd_all.h"
654		#undef CONFIG_CMD_NET
655
656	Other Commands:
657		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
658
659	Note:	Don't enable the "icache" and "dcache" commands
660		(configuration option CONFIG_CMD_CACHE) unless you know
661		what you (and your U-Boot users) are doing. Data
662		cache cannot be enabled on systems like the 8xx or
663		8260 (where accesses to the IMMR region must be
664		uncached), and it cannot be disabled on all other
665		systems where we (mis-) use the data cache to hold an
666		initial stack and some data.
667
668
669		XXX - this list needs to get updated!
670
671- Watchdog:
672		CONFIG_WATCHDOG
673		If this variable is defined, it enables watchdog
674		support. There must be support in the platform specific
675		code for a watchdog. For the 8xx and 8260 CPUs, the
676		SIU Watchdog feature is enabled in the SYPCR
677		register.
678
679- U-Boot Version:
680		CONFIG_VERSION_VARIABLE
681		If this variable is defined, an environment variable
682		named "ver" is created by U-Boot showing the U-Boot
683		version as printed by the "version" command.
684		This variable is readonly.
685
686- Real-Time Clock:
687
688		When CONFIG_CMD_DATE is selected, the type of the RTC
689		has to be selected, too. Define exactly one of the
690		following options:
691
692		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
693		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
694		CONFIG_RTC_MC13783	- use MC13783 RTC
695		CONFIG_RTC_MC146818	- use MC146818 RTC
696		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
697		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
698		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
699		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
700		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
701		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
702		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
703
704		Note that if the RTC uses I2C, then the I2C interface
705		must also be configured. See I2C Support, below.
706
707- GPIO Support:
708		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
709		CONFIG_PCA953X_INFO	- enable pca953x info command
710
711		Note that if the GPIO device uses I2C, then the I2C interface
712		must also be configured. See I2C Support, below.
713
714- Timestamp Support:
715
716		When CONFIG_TIMESTAMP is selected, the timestamp
717		(date and time) of an image is printed by image
718		commands like bootm or iminfo. This option is
719		automatically enabled when you select CONFIG_CMD_DATE .
720
721- Partition Support:
722		CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
723		and/or CONFIG_ISO_PARTITION and/or CONFIG_EFI_PARTITION
724
725		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
726		CONFIG_CMD_SCSI) you must configure support for at
727		least one partition type as well.
728
729- IDE Reset method:
730		CONFIG_IDE_RESET_ROUTINE - this is defined in several
731		board configurations files but used nowhere!
732
733		CONFIG_IDE_RESET - is this is defined, IDE Reset will
734		be performed by calling the function
735			ide_set_reset(int reset)
736		which has to be defined in a board specific file
737
738- ATAPI Support:
739		CONFIG_ATAPI
740
741		Set this to enable ATAPI support.
742
743- LBA48 Support
744		CONFIG_LBA48
745
746		Set this to enable support for disks larger than 137GB
747		Also look at CONFIG_SYS_64BIT_LBA ,CONFIG_SYS_64BIT_VSPRINTF and CONFIG_SYS_64BIT_STRTOUL
748		Whithout these , LBA48 support uses 32bit variables and will 'only'
749		support disks up to 2.1TB.
750
751		CONFIG_SYS_64BIT_LBA:
752			When enabled, makes the IDE subsystem use 64bit sector addresses.
753			Default is 32bit.
754
755- SCSI Support:
756		At the moment only there is only support for the
757		SYM53C8XX SCSI controller; define
758		CONFIG_SCSI_SYM53C8XX to enable it.
759
760		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
761		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
762		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
763		maximum numbers of LUNs, SCSI ID's and target
764		devices.
765		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
766
767- NETWORK Support (PCI):
768		CONFIG_E1000
769		Support for Intel 8254x gigabit chips.
770
771		CONFIG_E1000_FALLBACK_MAC
772		default MAC for empty EEPROM after production.
773
774		CONFIG_EEPRO100
775		Support for Intel 82557/82559/82559ER chips.
776		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
777		write routine for first time initialisation.
778
779		CONFIG_TULIP
780		Support for Digital 2114x chips.
781		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
782		modem chip initialisation (KS8761/QS6611).
783
784		CONFIG_NATSEMI
785		Support for National dp83815 chips.
786
787		CONFIG_NS8382X
788		Support for National dp8382[01] gigabit chips.
789
790- NETWORK Support (other):
791
792		CONFIG_DRIVER_LAN91C96
793		Support for SMSC's LAN91C96 chips.
794
795			CONFIG_LAN91C96_BASE
796			Define this to hold the physical address
797			of the LAN91C96's I/O space
798
799			CONFIG_LAN91C96_USE_32_BIT
800			Define this to enable 32 bit addressing
801
802		CONFIG_DRIVER_SMC91111
803		Support for SMSC's LAN91C111 chip
804
805			CONFIG_SMC91111_BASE
806			Define this to hold the physical address
807			of the device (I/O space)
808
809			CONFIG_SMC_USE_32_BIT
810			Define this if data bus is 32 bits
811
812			CONFIG_SMC_USE_IOFUNCS
813			Define this to use i/o functions instead of macros
814			(some hardware wont work with macros)
815
816		CONFIG_DRIVER_SMC911X
817		Support for SMSC's LAN911x and LAN921x chips
818
819			CONFIG_DRIVER_SMC911X_BASE
820			Define this to hold the physical address
821			of the device (I/O space)
822
823			CONFIG_DRIVER_SMC911X_32_BIT
824			Define this if data bus is 32 bits
825
826			CONFIG_DRIVER_SMC911X_16_BIT
827			Define this if data bus is 16 bits. If your processor
828			automatically converts one 32 bit word to two 16 bit
829			words you may also try CONFIG_DRIVER_SMC911X_32_BIT.
830
831- USB Support:
832		At the moment only the UHCI host controller is
833		supported (PIP405, MIP405, MPC5200); define
834		CONFIG_USB_UHCI to enable it.
835		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
836		and define CONFIG_USB_STORAGE to enable the USB
837		storage devices.
838		Note:
839		Supported are USB Keyboards and USB Floppy drives
840		(TEAC FD-05PUB).
841		MPC5200 USB requires additional defines:
842			CONFIG_USB_CLOCK
843				for 528 MHz Clock: 0x0001bbbb
844			CONFIG_USB_CONFIG
845				for differential drivers: 0x00001000
846				for single ended drivers: 0x00005000
847			CONFIG_SYS_USB_EVENT_POLL
848				May be defined to allow interrupt polling
849				instead of using asynchronous interrupts
850
851- USB Device:
852		Define the below if you wish to use the USB console.
853		Once firmware is rebuilt from a serial console issue the
854		command "setenv stdin usbtty; setenv stdout usbtty" and
855		attach your USB cable. The Unix command "dmesg" should print
856		it has found a new device. The environment variable usbtty
857		can be set to gserial or cdc_acm to enable your device to
858		appear to a USB host as a Linux gserial device or a
859		Common Device Class Abstract Control Model serial device.
860		If you select usbtty = gserial you should be able to enumerate
861		a Linux host by
862		# modprobe usbserial vendor=0xVendorID product=0xProductID
863		else if using cdc_acm, simply setting the environment
864		variable usbtty to be cdc_acm should suffice. The following
865		might be defined in YourBoardName.h
866
867			CONFIG_USB_DEVICE
868			Define this to build a UDC device
869
870			CONFIG_USB_TTY
871			Define this to have a tty type of device available to
872			talk to the UDC device
873
874			CONFIG_SYS_CONSOLE_IS_IN_ENV
875			Define this if you want stdin, stdout &/or stderr to
876			be set to usbtty.
877
878			mpc8xx:
879				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
880				Derive USB clock from external clock "blah"
881				- CONFIG_SYS_USB_EXTC_CLK 0x02
882
883				CONFIG_SYS_USB_BRG_CLK 0xBLAH
884				Derive USB clock from brgclk
885				- CONFIG_SYS_USB_BRG_CLK 0x04
886
887		If you have a USB-IF assigned VendorID then you may wish to
888		define your own vendor specific values either in BoardName.h
889		or directly in usbd_vendor_info.h. If you don't define
890		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
891		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
892		should pretend to be a Linux device to it's target host.
893
894			CONFIG_USBD_MANUFACTURER
895			Define this string as the name of your company for
896			- CONFIG_USBD_MANUFACTURER "my company"
897
898			CONFIG_USBD_PRODUCT_NAME
899			Define this string as the name of your product
900			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
901
902			CONFIG_USBD_VENDORID
903			Define this as your assigned Vendor ID from the USB
904			Implementors Forum. This *must* be a genuine Vendor ID
905			to avoid polluting the USB namespace.
906			- CONFIG_USBD_VENDORID 0xFFFF
907
908			CONFIG_USBD_PRODUCTID
909			Define this as the unique Product ID
910			for your device
911			- CONFIG_USBD_PRODUCTID 0xFFFF
912
913
914- MMC Support:
915		The MMC controller on the Intel PXA is supported. To
916		enable this define CONFIG_MMC. The MMC can be
917		accessed from the boot prompt by mapping the device
918		to physical memory similar to flash. Command line is
919		enabled with CONFIG_CMD_MMC. The MMC driver also works with
920		the FAT fs. This is enabled with CONFIG_CMD_FAT.
921
922- Journaling Flash filesystem support:
923		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
924		CONFIG_JFFS2_NAND_DEV
925		Define these for a default partition on a NAND device
926
927		CONFIG_SYS_JFFS2_FIRST_SECTOR,
928		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
929		Define these for a default partition on a NOR device
930
931		CONFIG_SYS_JFFS_CUSTOM_PART
932		Define this to create an own partition. You have to provide a
933		function struct part_info* jffs2_part_info(int part_num)
934
935		If you define only one JFFS2 partition you may also want to
936		#define CONFIG_SYS_JFFS_SINGLE_PART	1
937		to disable the command chpart. This is the default when you
938		have not defined a custom partition
939
940- Keyboard Support:
941		CONFIG_ISA_KEYBOARD
942
943		Define this to enable standard (PC-Style) keyboard
944		support
945
946		CONFIG_I8042_KBD
947		Standard PC keyboard driver with US (is default) and
948		GERMAN key layout (switch via environment 'keymap=de') support.
949		Export function i8042_kbd_init, i8042_tstc and i8042_getc
950		for cfb_console. Supports cursor blinking.
951
952- Video support:
953		CONFIG_VIDEO
954
955		Define this to enable video support (for output to
956		video).
957
958		CONFIG_VIDEO_CT69000
959
960		Enable Chips & Technologies 69000 Video chip
961
962		CONFIG_VIDEO_SMI_LYNXEM
963		Enable Silicon Motion SMI 712/710/810 Video chip. The
964		video output is selected via environment 'videoout'
965		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
966		assumed.
967
968		For the CT69000 and SMI_LYNXEM drivers, videomode is
969		selected via environment 'videomode'. Two different ways
970		are possible:
971		- "videomode=num"   'num' is a standard LiLo mode numbers.
972		Following standard modes are supported	(* is default):
973
974		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
975		-------------+---------------------------------------------
976		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
977		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
978		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
979		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
980		-------------+---------------------------------------------
981		(i.e. setenv videomode 317; saveenv; reset;)
982
983		- "videomode=bootargs" all the video parameters are parsed
984		from the bootargs. (See drivers/video/videomodes.c)
985
986
987		CONFIG_VIDEO_SED13806
988		Enable Epson SED13806 driver. This driver supports 8bpp
989		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
990		or CONFIG_VIDEO_SED13806_16BPP
991
992- Keyboard Support:
993		CONFIG_KEYBOARD
994
995		Define this to enable a custom keyboard support.
996		This simply calls drv_keyboard_init() which must be
997		defined in your board-specific files.
998		The only board using this so far is RBC823.
999
1000- LCD Support:	CONFIG_LCD
1001
1002		Define this to enable LCD support (for output to LCD
1003		display); also select one of the supported displays
1004		by defining one of these:
1005
1006		CONFIG_ATMEL_LCD:
1007
1008			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1009
1010		CONFIG_NEC_NL6448AC33:
1011
1012			NEC NL6448AC33-18. Active, color, single scan.
1013
1014		CONFIG_NEC_NL6448BC20
1015
1016			NEC NL6448BC20-08. 6.5", 640x480.
1017			Active, color, single scan.
1018
1019		CONFIG_NEC_NL6448BC33_54
1020
1021			NEC NL6448BC33-54. 10.4", 640x480.
1022			Active, color, single scan.
1023
1024		CONFIG_SHARP_16x9
1025
1026			Sharp 320x240. Active, color, single scan.
1027			It isn't 16x9, and I am not sure what it is.
1028
1029		CONFIG_SHARP_LQ64D341
1030
1031			Sharp LQ64D341 display, 640x480.
1032			Active, color, single scan.
1033
1034		CONFIG_HLD1045
1035
1036			HLD1045 display, 640x480.
1037			Active, color, single scan.
1038
1039		CONFIG_OPTREX_BW
1040
1041			Optrex	 CBL50840-2 NF-FW 99 22 M5
1042			or
1043			Hitachi	 LMG6912RPFC-00T
1044			or
1045			Hitachi	 SP14Q002
1046
1047			320x240. Black & white.
1048
1049		Normally display is black on white background; define
1050		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1051
1052- Splash Screen Support: CONFIG_SPLASH_SCREEN
1053
1054		If this option is set, the environment is checked for
1055		a variable "splashimage". If found, the usual display
1056		of logo, copyright and system information on the LCD
1057		is suppressed and the BMP image at the address
1058		specified in "splashimage" is loaded instead. The
1059		console is redirected to the "nulldev", too. This
1060		allows for a "silent" boot where a splash screen is
1061		loaded very quickly after power-on.
1062
1063- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1064
1065		If this option is set, additionally to standard BMP
1066		images, gzipped BMP images can be displayed via the
1067		splashscreen support or the bmp command.
1068
1069- Compression support:
1070		CONFIG_BZIP2
1071
1072		If this option is set, support for bzip2 compressed
1073		images is included. If not, only uncompressed and gzip
1074		compressed images are supported.
1075
1076		NOTE: the bzip2 algorithm requires a lot of RAM, so
1077		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1078		be at least 4MB.
1079
1080		CONFIG_LZMA
1081
1082		If this option is set, support for lzma compressed
1083		images is included.
1084
1085		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1086		requires an amount of dynamic memory that is given by the
1087		formula:
1088
1089			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1090
1091		Where lc and lp stand for, respectively, Literal context bits
1092		and Literal pos bits.
1093
1094		This value is upper-bounded by 14MB in the worst case. Anyway,
1095		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1096		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1097		a very small buffer.
1098
1099		Use the lzmainfo tool to determinate the lc and lp values and
1100		then calculate the amount of needed dynamic memory (ensuring
1101		the appropriate CONFIG_SYS_MALLOC_LEN value).
1102
1103- MII/PHY support:
1104		CONFIG_PHY_ADDR
1105
1106		The address of PHY on MII bus.
1107
1108		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1109
1110		The clock frequency of the MII bus
1111
1112		CONFIG_PHY_GIGE
1113
1114		If this option is set, support for speed/duplex
1115		detection of gigabit PHY is included.
1116
1117		CONFIG_PHY_RESET_DELAY
1118
1119		Some PHY like Intel LXT971A need extra delay after
1120		reset before any MII register access is possible.
1121		For such PHY, set this option to the usec delay
1122		required. (minimum 300usec for LXT971A)
1123
1124		CONFIG_PHY_CMD_DELAY (ppc4xx)
1125
1126		Some PHY like Intel LXT971A need extra delay after
1127		command issued before MII status register can be read
1128
1129- Ethernet address:
1130		CONFIG_ETHADDR
1131		CONFIG_ETH1ADDR
1132		CONFIG_ETH2ADDR
1133		CONFIG_ETH3ADDR
1134		CONFIG_ETH4ADDR
1135		CONFIG_ETH5ADDR
1136
1137		Define a default value for Ethernet address to use
1138		for the respective Ethernet interface, in case this
1139		is not determined automatically.
1140
1141- IP address:
1142		CONFIG_IPADDR
1143
1144		Define a default value for the IP address to use for
1145		the default Ethernet interface, in case this is not
1146		determined through e.g. bootp.
1147
1148- Server IP address:
1149		CONFIG_SERVERIP
1150
1151		Defines a default value for the IP address of a TFTP
1152		server to contact when using the "tftboot" command.
1153
1154- Multicast TFTP Mode:
1155		CONFIG_MCAST_TFTP
1156
1157		Defines whether you want to support multicast TFTP as per
1158		rfc-2090; for example to work with atftp.  Lets lots of targets
1159		tftp down the same boot image concurrently.  Note: the Ethernet
1160		driver in use must provide a function: mcast() to join/leave a
1161		multicast group.
1162
1163		CONFIG_BOOTP_RANDOM_DELAY
1164- BOOTP Recovery Mode:
1165		CONFIG_BOOTP_RANDOM_DELAY
1166
1167		If you have many targets in a network that try to
1168		boot using BOOTP, you may want to avoid that all
1169		systems send out BOOTP requests at precisely the same
1170		moment (which would happen for instance at recovery
1171		from a power failure, when all systems will try to
1172		boot, thus flooding the BOOTP server. Defining
1173		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1174		inserted before sending out BOOTP requests. The
1175		following delays are inserted then:
1176
1177		1st BOOTP request:	delay 0 ... 1 sec
1178		2nd BOOTP request:	delay 0 ... 2 sec
1179		3rd BOOTP request:	delay 0 ... 4 sec
1180		4th and following
1181		BOOTP requests:		delay 0 ... 8 sec
1182
1183- DHCP Advanced Options:
1184		You can fine tune the DHCP functionality by defining
1185		CONFIG_BOOTP_* symbols:
1186
1187		CONFIG_BOOTP_SUBNETMASK
1188		CONFIG_BOOTP_GATEWAY
1189		CONFIG_BOOTP_HOSTNAME
1190		CONFIG_BOOTP_NISDOMAIN
1191		CONFIG_BOOTP_BOOTPATH
1192		CONFIG_BOOTP_BOOTFILESIZE
1193		CONFIG_BOOTP_DNS
1194		CONFIG_BOOTP_DNS2
1195		CONFIG_BOOTP_SEND_HOSTNAME
1196		CONFIG_BOOTP_NTPSERVER
1197		CONFIG_BOOTP_TIMEOFFSET
1198		CONFIG_BOOTP_VENDOREX
1199
1200		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1201		environment variable, not the BOOTP server.
1202
1203		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1204		serverip from a DHCP server, it is possible that more
1205		than one DNS serverip is offered to the client.
1206		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1207		serverip will be stored in the additional environment
1208		variable "dnsip2". The first DNS serverip is always
1209		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1210		is defined.
1211
1212		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1213		to do a dynamic update of a DNS server. To do this, they
1214		need the hostname of the DHCP requester.
1215		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1216		of the "hostname" environment variable is passed as
1217		option 12 to the DHCP server.
1218
1219		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1220
1221		A 32bit value in microseconds for a delay between
1222		receiving a "DHCP Offer" and sending the "DHCP Request".
1223		This fixes a problem with certain DHCP servers that don't
1224		respond 100% of the time to a "DHCP request". E.g. On an
1225		AT91RM9200 processor running at 180MHz, this delay needed
1226		to be *at least* 15,000 usec before a Windows Server 2003
1227		DHCP server would reply 100% of the time. I recommend at
1228		least 50,000 usec to be safe. The alternative is to hope
1229		that one of the retries will be successful but note that
1230		the DHCP timeout and retry process takes a longer than
1231		this delay.
1232
1233 - CDP Options:
1234		CONFIG_CDP_DEVICE_ID
1235
1236		The device id used in CDP trigger frames.
1237
1238		CONFIG_CDP_DEVICE_ID_PREFIX
1239
1240		A two character string which is prefixed to the MAC address
1241		of the device.
1242
1243		CONFIG_CDP_PORT_ID
1244
1245		A printf format string which contains the ascii name of
1246		the port. Normally is set to "eth%d" which sets
1247		eth0 for the first Ethernet, eth1 for the second etc.
1248
1249		CONFIG_CDP_CAPABILITIES
1250
1251		A 32bit integer which indicates the device capabilities;
1252		0x00000010 for a normal host which does not forwards.
1253
1254		CONFIG_CDP_VERSION
1255
1256		An ascii string containing the version of the software.
1257
1258		CONFIG_CDP_PLATFORM
1259
1260		An ascii string containing the name of the platform.
1261
1262		CONFIG_CDP_TRIGGER
1263
1264		A 32bit integer sent on the trigger.
1265
1266		CONFIG_CDP_POWER_CONSUMPTION
1267
1268		A 16bit integer containing the power consumption of the
1269		device in .1 of milliwatts.
1270
1271		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1272
1273		A byte containing the id of the VLAN.
1274
1275- Status LED:	CONFIG_STATUS_LED
1276
1277		Several configurations allow to display the current
1278		status using a LED. For instance, the LED will blink
1279		fast while running U-Boot code, stop blinking as
1280		soon as a reply to a BOOTP request was received, and
1281		start blinking slow once the Linux kernel is running
1282		(supported by a status LED driver in the Linux
1283		kernel). Defining CONFIG_STATUS_LED enables this
1284		feature in U-Boot.
1285
1286- CAN Support:	CONFIG_CAN_DRIVER
1287
1288		Defining CONFIG_CAN_DRIVER enables CAN driver support
1289		on those systems that support this (optional)
1290		feature, like the TQM8xxL modules.
1291
1292- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1293
1294		These enable I2C serial bus commands. Defining either of
1295		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1296		include the appropriate I2C driver for the selected CPU.
1297
1298		This will allow you to use i2c commands at the u-boot
1299		command line (as long as you set CONFIG_CMD_I2C in
1300		CONFIG_COMMANDS) and communicate with i2c based realtime
1301		clock chips. See common/cmd_i2c.c for a description of the
1302		command line interface.
1303
1304		CONFIG_I2C_CMD_TREE is a recommended option that places
1305		all I2C commands under a single 'i2c' root command.  The
1306		older 'imm', 'imd', 'iprobe' etc. commands are considered
1307		deprecated and may disappear in the future.
1308
1309		CONFIG_HARD_I2C selects a hardware I2C controller.
1310
1311		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1312		bit-banging) driver instead of CPM or similar hardware
1313		support for I2C.
1314
1315		There are several other quantities that must also be
1316		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1317
1318		In both cases you will need to define CONFIG_SYS_I2C_SPEED
1319		to be the frequency (in Hz) at which you wish your i2c bus
1320		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
1321		the CPU's i2c node address).
1322
1323		Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
1324		sets the CPU up as a master node and so its address should
1325		therefore be cleared to 0 (See, eg, MPC823e User's Manual
1326		p.16-473). So, set CONFIG_SYS_I2C_SLAVE to 0.
1327
1328		That's all that's required for CONFIG_HARD_I2C.
1329
1330		If you use the software i2c interface (CONFIG_SOFT_I2C)
1331		then the following macros need to be defined (examples are
1332		from include/configs/lwmon.h):
1333
1334		I2C_INIT
1335
1336		(Optional). Any commands necessary to enable the I2C
1337		controller or configure ports.
1338
1339		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
1340
1341		I2C_PORT
1342
1343		(Only for MPC8260 CPU). The I/O port to use (the code
1344		assumes both bits are on the same port). Valid values
1345		are 0..3 for ports A..D.
1346
1347		I2C_ACTIVE
1348
1349		The code necessary to make the I2C data line active
1350		(driven).  If the data line is open collector, this
1351		define can be null.
1352
1353		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1354
1355		I2C_TRISTATE
1356
1357		The code necessary to make the I2C data line tri-stated
1358		(inactive).  If the data line is open collector, this
1359		define can be null.
1360
1361		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1362
1363		I2C_READ
1364
1365		Code that returns TRUE if the I2C data line is high,
1366		FALSE if it is low.
1367
1368		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1369
1370		I2C_SDA(bit)
1371
1372		If <bit> is TRUE, sets the I2C data line high. If it
1373		is FALSE, it clears it (low).
1374
1375		eg: #define I2C_SDA(bit) \
1376			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1377			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
1378
1379		I2C_SCL(bit)
1380
1381		If <bit> is TRUE, sets the I2C clock line high. If it
1382		is FALSE, it clears it (low).
1383
1384		eg: #define I2C_SCL(bit) \
1385			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1386			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
1387
1388		I2C_DELAY
1389
1390		This delay is invoked four times per clock cycle so this
1391		controls the rate of data transfer.  The data rate thus
1392		is 1 / (I2C_DELAY * 4). Often defined to be something
1393		like:
1394
1395		#define I2C_DELAY  udelay(2)
1396
1397		CONFIG_SYS_I2C_INIT_BOARD
1398
1399		When a board is reset during an i2c bus transfer
1400		chips might think that the current transfer is still
1401		in progress. On some boards it is possible to access
1402		the i2c SCLK line directly, either by using the
1403		processor pin as a GPIO or by having a second pin
1404		connected to the bus. If this option is defined a
1405		custom i2c_init_board() routine in boards/xxx/board.c
1406		is run early in the boot sequence.
1407
1408		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1409
1410		This option enables configuration of bi_iic_fast[] flags
1411		in u-boot bd_info structure based on u-boot environment
1412		variable "i2cfast". (see also i2cfast)
1413
1414		CONFIG_I2C_MULTI_BUS
1415
1416		This option allows the use of multiple I2C buses, each of which
1417		must have a controller.  At any point in time, only one bus is
1418		active.  To switch to a different bus, use the 'i2c dev' command.
1419		Note that bus numbering is zero-based.
1420
1421		CONFIG_SYS_I2C_NOPROBES
1422
1423		This option specifies a list of I2C devices that will be skipped
1424		when the 'i2c probe' command is issued (or 'iprobe' using the legacy
1425		command).  If CONFIG_I2C_MULTI_BUS is set, specify a list of bus-device
1426		pairs.	Otherwise, specify a 1D array of device addresses
1427
1428		e.g.
1429			#undef	CONFIG_I2C_MULTI_BUS
1430			#define CONFIG_SYS_I2C_NOPROBES	{0x50,0x68}
1431
1432		will skip addresses 0x50 and 0x68 on a board with one I2C bus
1433
1434			#define	CONFIG_I2C_MULTI_BUS
1435			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
1436
1437		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1438
1439		CONFIG_SYS_SPD_BUS_NUM
1440
1441		If defined, then this indicates the I2C bus number for DDR SPD.
1442		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1443
1444		CONFIG_SYS_RTC_BUS_NUM
1445
1446		If defined, then this indicates the I2C bus number for the RTC.
1447		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1448
1449		CONFIG_SYS_DTT_BUS_NUM
1450
1451		If defined, then this indicates the I2C bus number for the DTT.
1452		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
1453
1454		CONFIG_SYS_I2C_DTT_ADDR:
1455
1456		If defined, specifies the I2C address of the DTT device.
1457		If not defined, then U-Boot uses predefined value for
1458		specified DTT device.
1459
1460		CONFIG_FSL_I2C
1461
1462		Define this option if you want to use Freescale's I2C driver in
1463		drivers/i2c/fsl_i2c.c.
1464
1465		CONFIG_I2C_MUX
1466
1467		Define this option if you have I2C devices reached over 1 .. n
1468		I2C Muxes like the pca9544a. This option addes a new I2C
1469		Command "i2c bus [muxtype:muxaddr:muxchannel]" which adds a
1470		new I2C Bus to the existing I2C Busses. If you select the
1471		new Bus with "i2c dev", u-bbot sends first the commandos for
1472		the muxes to activate this new "bus".
1473
1474		CONFIG_I2C_MULTI_BUS must be also defined, to use this
1475		feature!
1476
1477		Example:
1478		Adding a new I2C Bus reached over 2 pca9544a muxes
1479			The First mux with address 70 and channel 6
1480			The Second mux with address 71 and channel 4
1481
1482		=> i2c bus pca9544a:70:6:pca9544a:71:4
1483
1484		Use the "i2c bus" command without parameter, to get a list
1485		of I2C Busses with muxes:
1486
1487		=> i2c bus
1488		Busses reached over muxes:
1489		Bus ID: 2
1490		  reached over Mux(es):
1491		    pca9544a@70 ch: 4
1492		Bus ID: 3
1493		  reached over Mux(es):
1494		    pca9544a@70 ch: 6
1495		    pca9544a@71 ch: 4
1496		=>
1497
1498		If you now switch to the new I2C Bus 3 with "i2c dev 3"
1499		u-boot sends First the Commando to the mux@70 to enable
1500		channel 6, and then the Commando to the mux@71 to enable
1501		the channel 4.
1502
1503		After that, you can use the "normal" i2c commands as
1504		usual, to communicate with your I2C devices behind
1505		the 2 muxes.
1506
1507		This option is actually implemented for the bitbanging
1508		algorithm in common/soft_i2c.c and for the Hardware I2C
1509		Bus on the MPC8260. But it should be not so difficult
1510		to add this option to other architectures.
1511
1512		CONFIG_SOFT_I2C_READ_REPEATED_START
1513
1514		defining this will force the i2c_read() function in
1515		the soft_i2c driver to perform an I2C repeated start
1516		between writing the address pointer and reading the
1517		data.  If this define is omitted the default behaviour
1518		of doing a stop-start sequence will be used.  Most I2C
1519		devices can use either method, but some require one or
1520		the other.
1521
1522- SPI Support:	CONFIG_SPI
1523
1524		Enables SPI driver (so far only tested with
1525		SPI EEPROM, also an instance works with Crystal A/D and
1526		D/As on the SACSng board)
1527
1528		CONFIG_SPI_X
1529
1530		Enables extended (16-bit) SPI EEPROM addressing.
1531		(symmetrical to CONFIG_I2C_X)
1532
1533		CONFIG_SOFT_SPI
1534
1535		Enables a software (bit-bang) SPI driver rather than
1536		using hardware support. This is a general purpose
1537		driver that only requires three general I/O port pins
1538		(two outputs, one input) to function. If this is
1539		defined, the board configuration must define several
1540		SPI configuration items (port pins to use, etc). For
1541		an example, see include/configs/sacsng.h.
1542
1543		CONFIG_HARD_SPI
1544
1545		Enables a hardware SPI driver for general-purpose reads
1546		and writes.  As with CONFIG_SOFT_SPI, the board configuration
1547		must define a list of chip-select function pointers.
1548		Currently supported on some MPC8xxx processors.  For an
1549		example, see include/configs/mpc8349emds.h.
1550
1551		CONFIG_MXC_SPI
1552
1553		Enables the driver for the SPI controllers on i.MX and MXC
1554		SoCs. Currently only i.MX31 is supported.
1555
1556- FPGA Support: CONFIG_FPGA
1557
1558		Enables FPGA subsystem.
1559
1560		CONFIG_FPGA_<vendor>
1561
1562		Enables support for specific chip vendors.
1563		(ALTERA, XILINX)
1564
1565		CONFIG_FPGA_<family>
1566
1567		Enables support for FPGA family.
1568		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1569
1570		CONFIG_FPGA_COUNT
1571
1572		Specify the number of FPGA devices to support.
1573
1574		CONFIG_SYS_FPGA_PROG_FEEDBACK
1575
1576		Enable printing of hash marks during FPGA configuration.
1577
1578		CONFIG_SYS_FPGA_CHECK_BUSY
1579
1580		Enable checks on FPGA configuration interface busy
1581		status by the configuration function. This option
1582		will require a board or device specific function to
1583		be written.
1584
1585		CONFIG_FPGA_DELAY
1586
1587		If defined, a function that provides delays in the FPGA
1588		configuration driver.
1589
1590		CONFIG_SYS_FPGA_CHECK_CTRLC
1591		Allow Control-C to interrupt FPGA configuration
1592
1593		CONFIG_SYS_FPGA_CHECK_ERROR
1594
1595		Check for configuration errors during FPGA bitfile
1596		loading. For example, abort during Virtex II
1597		configuration if the INIT_B line goes low (which
1598		indicated a CRC error).
1599
1600		CONFIG_SYS_FPGA_WAIT_INIT
1601
1602		Maximum time to wait for the INIT_B line to deassert
1603		after PROB_B has been deasserted during a Virtex II
1604		FPGA configuration sequence. The default time is 500
1605		ms.
1606
1607		CONFIG_SYS_FPGA_WAIT_BUSY
1608
1609		Maximum time to wait for BUSY to deassert during
1610		Virtex II FPGA configuration. The default is 5 ms.
1611
1612		CONFIG_SYS_FPGA_WAIT_CONFIG
1613
1614		Time to wait after FPGA configuration. The default is
1615		200 ms.
1616
1617- Configuration Management:
1618		CONFIG_IDENT_STRING
1619
1620		If defined, this string will be added to the U-Boot
1621		version information (U_BOOT_VERSION)
1622
1623- Vendor Parameter Protection:
1624
1625		U-Boot considers the values of the environment
1626		variables "serial#" (Board Serial Number) and
1627		"ethaddr" (Ethernet Address) to be parameters that
1628		are set once by the board vendor / manufacturer, and
1629		protects these variables from casual modification by
1630		the user. Once set, these variables are read-only,
1631		and write or delete attempts are rejected. You can
1632		change this behaviour:
1633
1634		If CONFIG_ENV_OVERWRITE is #defined in your config
1635		file, the write protection for vendor parameters is
1636		completely disabled. Anybody can change or delete
1637		these parameters.
1638
1639		Alternatively, if you #define _both_ CONFIG_ETHADDR
1640		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1641		Ethernet address is installed in the environment,
1642		which can be changed exactly ONCE by the user. [The
1643		serial# is unaffected by this, i. e. it remains
1644		read-only.]
1645
1646- Protected RAM:
1647		CONFIG_PRAM
1648
1649		Define this variable to enable the reservation of
1650		"protected RAM", i. e. RAM which is not overwritten
1651		by U-Boot. Define CONFIG_PRAM to hold the number of
1652		kB you want to reserve for pRAM. You can overwrite
1653		this default value by defining an environment
1654		variable "pram" to the number of kB you want to
1655		reserve. Note that the board info structure will
1656		still show the full amount of RAM. If pRAM is
1657		reserved, a new environment variable "mem" will
1658		automatically be defined to hold the amount of
1659		remaining RAM in a form that can be passed as boot
1660		argument to Linux, for instance like that:
1661
1662			setenv bootargs ... mem=\${mem}
1663			saveenv
1664
1665		This way you can tell Linux not to use this memory,
1666		either, which results in a memory region that will
1667		not be affected by reboots.
1668
1669		*WARNING* If your board configuration uses automatic
1670		detection of the RAM size, you must make sure that
1671		this memory test is non-destructive. So far, the
1672		following board configurations are known to be
1673		"pRAM-clean":
1674
1675			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1676			HERMES, IP860, RPXlite, LWMON, LANTEC,
1677			PCU_E, FLAGADM, TQM8260
1678
1679- Error Recovery:
1680		CONFIG_PANIC_HANG
1681
1682		Define this variable to stop the system in case of a
1683		fatal error, so that you have to reset it manually.
1684		This is probably NOT a good idea for an embedded
1685		system where you want the system to reboot
1686		automatically as fast as possible, but it may be
1687		useful during development since you can try to debug
1688		the conditions that lead to the situation.
1689
1690		CONFIG_NET_RETRY_COUNT
1691
1692		This variable defines the number of retries for
1693		network operations like ARP, RARP, TFTP, or BOOTP
1694		before giving up the operation. If not defined, a
1695		default value of 5 is used.
1696
1697		CONFIG_ARP_TIMEOUT
1698
1699		Timeout waiting for an ARP reply in milliseconds.
1700
1701- Command Interpreter:
1702		CONFIG_AUTO_COMPLETE
1703
1704		Enable auto completion of commands using TAB.
1705
1706		Note that this feature has NOT been implemented yet
1707		for the "hush" shell.
1708
1709
1710		CONFIG_SYS_HUSH_PARSER
1711
1712		Define this variable to enable the "hush" shell (from
1713		Busybox) as command line interpreter, thus enabling
1714		powerful command line syntax like
1715		if...then...else...fi conditionals or `&&' and '||'
1716		constructs ("shell scripts").
1717
1718		If undefined, you get the old, much simpler behaviour
1719		with a somewhat smaller memory footprint.
1720
1721
1722		CONFIG_SYS_PROMPT_HUSH_PS2
1723
1724		This defines the secondary prompt string, which is
1725		printed when the command interpreter needs more input
1726		to complete a command. Usually "> ".
1727
1728	Note:
1729
1730		In the current implementation, the local variables
1731		space and global environment variables space are
1732		separated. Local variables are those you define by
1733		simply typing `name=value'. To access a local
1734		variable later on, you have write `$name' or
1735		`${name}'; to execute the contents of a variable
1736		directly type `$name' at the command prompt.
1737
1738		Global environment variables are those you use
1739		setenv/printenv to work with. To run a command stored
1740		in such a variable, you need to use the run command,
1741		and you must not use the '$' sign to access them.
1742
1743		To store commands and special characters in a
1744		variable, please use double quotation marks
1745		surrounding the whole text of the variable, instead
1746		of the backslashes before semicolons and special
1747		symbols.
1748
1749- Commandline Editing and History:
1750		CONFIG_CMDLINE_EDITING
1751
1752		Enable editing and History functions for interactive
1753		commandline input operations
1754
1755- Default Environment:
1756		CONFIG_EXTRA_ENV_SETTINGS
1757
1758		Define this to contain any number of null terminated
1759		strings (variable = value pairs) that will be part of
1760		the default environment compiled into the boot image.
1761
1762		For example, place something like this in your
1763		board's config file:
1764
1765		#define CONFIG_EXTRA_ENV_SETTINGS \
1766			"myvar1=value1\0" \
1767			"myvar2=value2\0"
1768
1769		Warning: This method is based on knowledge about the
1770		internal format how the environment is stored by the
1771		U-Boot code. This is NOT an official, exported
1772		interface! Although it is unlikely that this format
1773		will change soon, there is no guarantee either.
1774		You better know what you are doing here.
1775
1776		Note: overly (ab)use of the default environment is
1777		discouraged. Make sure to check other ways to preset
1778		the environment like the autoscript function or the
1779		boot command first.
1780
1781- DataFlash Support:
1782		CONFIG_HAS_DATAFLASH
1783
1784		Defining this option enables DataFlash features and
1785		allows to read/write in Dataflash via the standard
1786		commands cp, md...
1787
1788- SystemACE Support:
1789		CONFIG_SYSTEMACE
1790
1791		Adding this option adds support for Xilinx SystemACE
1792		chips attached via some sort of local bus. The address
1793		of the chip must also be defined in the
1794		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
1795
1796		#define CONFIG_SYSTEMACE
1797		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
1798
1799		When SystemACE support is added, the "ace" device type
1800		becomes available to the fat commands, i.e. fatls.
1801
1802- TFTP Fixed UDP Port:
1803		CONFIG_TFTP_PORT
1804
1805		If this is defined, the environment variable tftpsrcp
1806		is used to supply the TFTP UDP source port value.
1807		If tftpsrcp isn't defined, the normal pseudo-random port
1808		number generator is used.
1809
1810		Also, the environment variable tftpdstp is used to supply
1811		the TFTP UDP destination port value.  If tftpdstp isn't
1812		defined, the normal port 69 is used.
1813
1814		The purpose for tftpsrcp is to allow a TFTP server to
1815		blindly start the TFTP transfer using the pre-configured
1816		target IP address and UDP port. This has the effect of
1817		"punching through" the (Windows XP) firewall, allowing
1818		the remainder of the TFTP transfer to proceed normally.
1819		A better solution is to properly configure the firewall,
1820		but sometimes that is not allowed.
1821
1822- Show boot progress:
1823		CONFIG_SHOW_BOOT_PROGRESS
1824
1825		Defining this option allows to add some board-
1826		specific code (calling a user-provided function
1827		"show_boot_progress(int)") that enables you to show
1828		the system's boot progress on some display (for
1829		example, some LED's) on your board. At the moment,
1830		the following checkpoints are implemented:
1831
1832- Automatic software updates via TFTP server
1833		CONFIG_UPDATE_TFTP
1834		CONFIG_UPDATE_TFTP_CNT_MAX
1835		CONFIG_UPDATE_TFTP_MSEC_MAX
1836
1837		These options enable and control the auto-update feature;
1838		for a more detailed description refer to doc/README.update.
1839
1840Legacy uImage format:
1841
1842  Arg	Where			When
1843    1	common/cmd_bootm.c	before attempting to boot an image
1844   -1	common/cmd_bootm.c	Image header has bad	 magic number
1845    2	common/cmd_bootm.c	Image header has correct magic number
1846   -2	common/cmd_bootm.c	Image header has bad	 checksum
1847    3	common/cmd_bootm.c	Image header has correct checksum
1848   -3	common/cmd_bootm.c	Image data   has bad	 checksum
1849    4	common/cmd_bootm.c	Image data   has correct checksum
1850   -4	common/cmd_bootm.c	Image is for unsupported architecture
1851    5	common/cmd_bootm.c	Architecture check OK
1852   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
1853    6	common/cmd_bootm.c	Image Type check OK
1854   -6	common/cmd_bootm.c	gunzip uncompression error
1855   -7	common/cmd_bootm.c	Unimplemented compression type
1856    7	common/cmd_bootm.c	Uncompression OK
1857    8	common/cmd_bootm.c	No uncompress/copy overwrite error
1858   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
1859
1860    9	common/image.c		Start initial ramdisk verification
1861  -10	common/image.c		Ramdisk header has bad	   magic number
1862  -11	common/image.c		Ramdisk header has bad	   checksum
1863   10	common/image.c		Ramdisk header is OK
1864  -12	common/image.c		Ramdisk data   has bad	   checksum
1865   11	common/image.c		Ramdisk data   has correct checksum
1866   12	common/image.c		Ramdisk verification complete, start loading
1867  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
1868   13	common/image.c		Start multifile image verification
1869   14	common/image.c		No initial ramdisk, no multifile, continue.
1870
1871   15	lib_<arch>/bootm.c	All preparation done, transferring control to OS
1872
1873  -30	lib_ppc/board.c		Fatal error, hang the system
1874  -31	post/post.c		POST test failed, detected by post_output_backlog()
1875  -32	post/post.c		POST test failed, detected by post_run_single()
1876
1877   34	common/cmd_doc.c	before loading a Image from a DOC device
1878  -35	common/cmd_doc.c	Bad usage of "doc" command
1879   35	common/cmd_doc.c	correct usage of "doc" command
1880  -36	common/cmd_doc.c	No boot device
1881   36	common/cmd_doc.c	correct boot device
1882  -37	common/cmd_doc.c	Unknown Chip ID on boot device
1883   37	common/cmd_doc.c	correct chip ID found, device available
1884  -38	common/cmd_doc.c	Read Error on boot device
1885   38	common/cmd_doc.c	reading Image header from DOC device OK
1886  -39	common/cmd_doc.c	Image header has bad magic number
1887   39	common/cmd_doc.c	Image header has correct magic number
1888  -40	common/cmd_doc.c	Error reading Image from DOC device
1889   40	common/cmd_doc.c	Image header has correct magic number
1890   41	common/cmd_ide.c	before loading a Image from a IDE device
1891  -42	common/cmd_ide.c	Bad usage of "ide" command
1892   42	common/cmd_ide.c	correct usage of "ide" command
1893  -43	common/cmd_ide.c	No boot device
1894   43	common/cmd_ide.c	boot device found
1895  -44	common/cmd_ide.c	Device not available
1896   44	common/cmd_ide.c	Device available
1897  -45	common/cmd_ide.c	wrong partition selected
1898   45	common/cmd_ide.c	partition selected
1899  -46	common/cmd_ide.c	Unknown partition table
1900   46	common/cmd_ide.c	valid partition table found
1901  -47	common/cmd_ide.c	Invalid partition type
1902   47	common/cmd_ide.c	correct partition type
1903  -48	common/cmd_ide.c	Error reading Image Header on boot device
1904   48	common/cmd_ide.c	reading Image Header from IDE device OK
1905  -49	common/cmd_ide.c	Image header has bad magic number
1906   49	common/cmd_ide.c	Image header has correct magic number
1907  -50	common/cmd_ide.c	Image header has bad	 checksum
1908   50	common/cmd_ide.c	Image header has correct checksum
1909  -51	common/cmd_ide.c	Error reading Image from IDE device
1910   51	common/cmd_ide.c	reading Image from IDE device OK
1911   52	common/cmd_nand.c	before loading a Image from a NAND device
1912  -53	common/cmd_nand.c	Bad usage of "nand" command
1913   53	common/cmd_nand.c	correct usage of "nand" command
1914  -54	common/cmd_nand.c	No boot device
1915   54	common/cmd_nand.c	boot device found
1916  -55	common/cmd_nand.c	Unknown Chip ID on boot device
1917   55	common/cmd_nand.c	correct chip ID found, device available
1918  -56	common/cmd_nand.c	Error reading Image Header on boot device
1919   56	common/cmd_nand.c	reading Image Header from NAND device OK
1920  -57	common/cmd_nand.c	Image header has bad magic number
1921   57	common/cmd_nand.c	Image header has correct magic number
1922  -58	common/cmd_nand.c	Error reading Image from NAND device
1923   58	common/cmd_nand.c	reading Image from NAND device OK
1924
1925  -60	common/env_common.c	Environment has a bad CRC, using default
1926
1927   64	net/eth.c		starting with Ethernet configuration.
1928  -64	net/eth.c		no Ethernet found.
1929   65	net/eth.c		Ethernet found.
1930
1931  -80	common/cmd_net.c	usage wrong
1932   80	common/cmd_net.c	before calling NetLoop()
1933  -81	common/cmd_net.c	some error in NetLoop() occurred
1934   81	common/cmd_net.c	NetLoop() back without error
1935  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
1936   82	common/cmd_net.c	trying automatic boot
1937   83	common/cmd_net.c	running autoscript
1938  -83	common/cmd_net.c	some error in automatic boot or autoscript
1939   84	common/cmd_net.c	end without errors
1940
1941FIT uImage format:
1942
1943  Arg	Where			When
1944  100	common/cmd_bootm.c	Kernel FIT Image has correct format
1945 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
1946  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
1947 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
1948  102	common/cmd_bootm.c	Kernel unit name specified
1949 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
1950  103	common/cmd_bootm.c	Found configuration node
1951  104	common/cmd_bootm.c	Got kernel subimage node offset
1952 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
1953  105	common/cmd_bootm.c	Kernel subimage hash verification OK
1954 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
1955  106	common/cmd_bootm.c	Architecture check OK
1956 -106	common/cmd_bootm.c	Kernel subimage has wrong type
1957  107	common/cmd_bootm.c	Kernel subimage type OK
1958 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
1959  108	common/cmd_bootm.c	Got kernel subimage data/size
1960 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
1961 -109	common/cmd_bootm.c	Can't get kernel subimage type
1962 -110	common/cmd_bootm.c	Can't get kernel subimage comp
1963 -111	common/cmd_bootm.c	Can't get kernel subimage os
1964 -112	common/cmd_bootm.c	Can't get kernel subimage load address
1965 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
1966
1967  120	common/image.c		Start initial ramdisk verification
1968 -120	common/image.c		Ramdisk FIT image has incorrect format
1969  121	common/image.c		Ramdisk FIT image has correct format
1970  122	common/image.c		No ramdisk subimage unit name, using configuration
1971 -122	common/image.c		Can't get configuration for ramdisk subimage
1972  123	common/image.c		Ramdisk unit name specified
1973 -124	common/image.c		Can't get ramdisk subimage node offset
1974  125	common/image.c		Got ramdisk subimage node offset
1975 -125	common/image.c		Ramdisk subimage hash verification failed
1976  126	common/image.c		Ramdisk subimage hash verification OK
1977 -126	common/image.c		Ramdisk subimage for unsupported architecture
1978  127	common/image.c		Architecture check OK
1979 -127	common/image.c		Can't get ramdisk subimage data/size
1980  128	common/image.c		Got ramdisk subimage data/size
1981  129	common/image.c		Can't get ramdisk load address
1982 -129	common/image.c		Got ramdisk load address
1983
1984 -130	common/cmd_doc.c	Incorrect FIT image format
1985  131	common/cmd_doc.c	FIT image format OK
1986
1987 -140	common/cmd_ide.c	Incorrect FIT image format
1988  141	common/cmd_ide.c	FIT image format OK
1989
1990 -150	common/cmd_nand.c	Incorrect FIT image format
1991  151	common/cmd_nand.c	FIT image format OK
1992
1993
1994Modem Support:
1995--------------
1996
1997[so far only for SMDK2400 and TRAB boards]
1998
1999- Modem support enable:
2000		CONFIG_MODEM_SUPPORT
2001
2002- RTS/CTS Flow control enable:
2003		CONFIG_HWFLOW
2004
2005- Modem debug support:
2006		CONFIG_MODEM_SUPPORT_DEBUG
2007
2008		Enables debugging stuff (char screen[1024], dbg())
2009		for modem support. Useful only with BDI2000.
2010
2011- Interrupt support (PPC):
2012
2013		There are common interrupt_init() and timer_interrupt()
2014		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2015		for CPU specific initialization. interrupt_init_cpu()
2016		should set decrementer_count to appropriate value. If
2017		CPU resets decrementer automatically after interrupt
2018		(ppc4xx) it should set decrementer_count to zero.
2019		timer_interrupt() calls timer_interrupt_cpu() for CPU
2020		specific handling. If board has watchdog / status_led
2021		/ other_activity_monitor it works automatically from
2022		general timer_interrupt().
2023
2024- General:
2025
2026		In the target system modem support is enabled when a
2027		specific key (key combination) is pressed during
2028		power-on. Otherwise U-Boot will boot normally
2029		(autoboot). The key_pressed() function is called from
2030		board_init(). Currently key_pressed() is a dummy
2031		function, returning 1 and thus enabling modem
2032		initialization.
2033
2034		If there are no modem init strings in the
2035		environment, U-Boot proceed to autoboot; the
2036		previous output (banner, info printfs) will be
2037		suppressed, though.
2038
2039		See also: doc/README.Modem
2040
2041
2042Configuration Settings:
2043-----------------------
2044
2045- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2046		undefine this when you're short of memory.
2047
2048- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
2049		prompt for user input.
2050
2051- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
2052
2053- CONFIG_SYS_PBSIZE:	Buffer size for Console output
2054
2055- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
2056
2057- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2058		the application (usually a Linux kernel) when it is
2059		booted
2060
2061- CONFIG_SYS_BAUDRATE_TABLE:
2062		List of legal baudrate settings for this board.
2063
2064- CONFIG_SYS_CONSOLE_INFO_QUIET
2065		Suppress display of console information at boot.
2066
2067- CONFIG_SYS_CONSOLE_IS_IN_ENV
2068		If the board specific function
2069			extern int overwrite_console (void);
2070		returns 1, the stdin, stderr and stdout are switched to the
2071		serial port, else the settings in the environment are used.
2072
2073- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
2074		Enable the call to overwrite_console().
2075
2076- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
2077		Enable overwrite of previous console environment settings.
2078
2079- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
2080		Begin and End addresses of the area used by the
2081		simple memory test.
2082
2083- CONFIG_SYS_ALT_MEMTEST:
2084		Enable an alternate, more extensive memory test.
2085
2086- CONFIG_SYS_MEMTEST_SCRATCH:
2087		Scratch address used by the alternate memory test
2088		You only need to set this if address zero isn't writeable
2089
2090- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
2091		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2092		this specified memory area will get subtracted from the top
2093		(end) of RAM and won't get "touched" at all by U-Boot. By
2094		fixing up gd->ram_size the Linux kernel should gets passed
2095		the now "corrected" memory size and won't touch it either.
2096		This should work for arch/ppc and arch/powerpc. Only Linux
2097		board ports in arch/powerpc with bootwrapper support that
2098		recalculate the memory size from the SDRAM controller setup
2099		will have to get fixed in Linux additionally.
2100
2101		This option can be used as a workaround for the 440EPx/GRx
2102		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2103		be touched.
2104
2105		WARNING: Please make sure that this value is a multiple of
2106		the Linux page size (normally 4k). If this is not the case,
2107		then the end address of the Linux memory will be located at a
2108		non page size aligned address and this could cause major
2109		problems.
2110
2111- CONFIG_SYS_TFTP_LOADADDR:
2112		Default load address for network file downloads
2113
2114- CONFIG_SYS_LOADS_BAUD_CHANGE:
2115		Enable temporary baudrate change while serial download
2116
2117- CONFIG_SYS_SDRAM_BASE:
2118		Physical start address of SDRAM. _Must_ be 0 here.
2119
2120- CONFIG_SYS_MBIO_BASE:
2121		Physical start address of Motherboard I/O (if using a
2122		Cogent motherboard)
2123
2124- CONFIG_SYS_FLASH_BASE:
2125		Physical start address of Flash memory.
2126
2127- CONFIG_SYS_MONITOR_BASE:
2128		Physical start address of boot monitor code (set by
2129		make config files to be same as the text base address
2130		(TEXT_BASE) used when linking) - same as
2131		CONFIG_SYS_FLASH_BASE when booting from flash.
2132
2133- CONFIG_SYS_MONITOR_LEN:
2134		Size of memory reserved for monitor code, used to
2135		determine _at_compile_time_ (!) if the environment is
2136		embedded within the U-Boot image, or in a separate
2137		flash sector.
2138
2139- CONFIG_SYS_MALLOC_LEN:
2140		Size of DRAM reserved for malloc() use.
2141
2142- CONFIG_SYS_BOOTM_LEN:
2143		Normally compressed uImages are limited to an
2144		uncompressed size of 8 MBytes. If this is not enough,
2145		you can define CONFIG_SYS_BOOTM_LEN in your board config file
2146		to adjust this setting to your needs.
2147
2148- CONFIG_SYS_BOOTMAPSZ:
2149		Maximum size of memory mapped by the startup code of
2150		the Linux kernel; all data that must be processed by
2151		the Linux kernel (bd_info, boot arguments, FDT blob if
2152		used) must be put below this limit, unless "bootm_low"
2153		enviroment variable is defined and non-zero. In such case
2154		all data for the Linux kernel must be between "bootm_low"
2155		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.
2156
2157- CONFIG_SYS_MAX_FLASH_BANKS:
2158		Max number of Flash memory banks
2159
2160- CONFIG_SYS_MAX_FLASH_SECT:
2161		Max number of sectors on a Flash chip
2162
2163- CONFIG_SYS_FLASH_ERASE_TOUT:
2164		Timeout for Flash erase operations (in ms)
2165
2166- CONFIG_SYS_FLASH_WRITE_TOUT:
2167		Timeout for Flash write operations (in ms)
2168
2169- CONFIG_SYS_FLASH_LOCK_TOUT
2170		Timeout for Flash set sector lock bit operation (in ms)
2171
2172- CONFIG_SYS_FLASH_UNLOCK_TOUT
2173		Timeout for Flash clear lock bits operation (in ms)
2174
2175- CONFIG_SYS_FLASH_PROTECTION
2176		If defined, hardware flash sectors protection is used
2177		instead of U-Boot software protection.
2178
2179- CONFIG_SYS_DIRECT_FLASH_TFTP:
2180
2181		Enable TFTP transfers directly to flash memory;
2182		without this option such a download has to be
2183		performed in two steps: (1) download to RAM, and (2)
2184		copy from RAM to flash.
2185
2186		The two-step approach is usually more reliable, since
2187		you can check if the download worked before you erase
2188		the flash, but in some situations (when system RAM is
2189		too limited to allow for a temporary copy of the
2190		downloaded image) this option may be very useful.
2191
2192- CONFIG_SYS_FLASH_CFI:
2193		Define if the flash driver uses extra elements in the
2194		common flash structure for storing flash geometry.
2195
2196- CONFIG_FLASH_CFI_DRIVER
2197		This option also enables the building of the cfi_flash driver
2198		in the drivers directory
2199
2200- CONFIG_FLASH_CFI_MTD
2201		This option enables the building of the cfi_mtd driver
2202		in the drivers directory. The driver exports CFI flash
2203		to the MTD layer.
2204
2205- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2206		Use buffered writes to flash.
2207
2208- CONFIG_FLASH_SPANSION_S29WS_N
2209		s29ws-n MirrorBit flash has non-standard addresses for buffered
2210		write commands.
2211
2212- CONFIG_SYS_FLASH_QUIET_TEST
2213		If this option is defined, the common CFI flash doesn't
2214		print it's warning upon not recognized FLASH banks. This
2215		is useful, if some of the configured banks are only
2216		optionally available.
2217
2218- CONFIG_FLASH_SHOW_PROGRESS
2219		If defined (must be an integer), print out countdown
2220		digits and dots.  Recommended value: 45 (9..1) for 80
2221		column displays, 15 (3..1) for 40 column displays.
2222
2223- CONFIG_SYS_RX_ETH_BUFFER:
2224		Defines the number of Ethernet receive buffers. On some
2225		Ethernet controllers it is recommended to set this value
2226		to 8 or even higher (EEPRO100 or 405 EMAC), since all
2227		buffers can be full shortly after enabling the interface
2228		on high Ethernet traffic.
2229		Defaults to 4 if not defined.
2230
2231The following definitions that deal with the placement and management
2232of environment data (variable area); in general, we support the
2233following configurations:
2234
2235- CONFIG_ENV_IS_IN_FLASH:
2236
2237	Define this if the environment is in flash memory.
2238
2239	a) The environment occupies one whole flash sector, which is
2240	   "embedded" in the text segment with the U-Boot code. This
2241	   happens usually with "bottom boot sector" or "top boot
2242	   sector" type flash chips, which have several smaller
2243	   sectors at the start or the end. For instance, such a
2244	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
2245	   such a case you would place the environment in one of the
2246	   4 kB sectors - with U-Boot code before and after it. With
2247	   "top boot sector" type flash chips, you would put the
2248	   environment in one of the last sectors, leaving a gap
2249	   between U-Boot and the environment.
2250
2251	- CONFIG_ENV_OFFSET:
2252
2253	   Offset of environment data (variable area) to the
2254	   beginning of flash memory; for instance, with bottom boot
2255	   type flash chips the second sector can be used: the offset
2256	   for this sector is given here.
2257
2258	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
2259
2260	- CONFIG_ENV_ADDR:
2261
2262	   This is just another way to specify the start address of
2263	   the flash sector containing the environment (instead of
2264	   CONFIG_ENV_OFFSET).
2265
2266	- CONFIG_ENV_SECT_SIZE:
2267
2268	   Size of the sector containing the environment.
2269
2270
2271	b) Sometimes flash chips have few, equal sized, BIG sectors.
2272	   In such a case you don't want to spend a whole sector for
2273	   the environment.
2274
2275	- CONFIG_ENV_SIZE:
2276
2277	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
2278	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
2279	   of this flash sector for the environment. This saves
2280	   memory for the RAM copy of the environment.
2281
2282	   It may also save flash memory if you decide to use this
2283	   when your environment is "embedded" within U-Boot code,
2284	   since then the remainder of the flash sector could be used
2285	   for U-Boot code. It should be pointed out that this is
2286	   STRONGLY DISCOURAGED from a robustness point of view:
2287	   updating the environment in flash makes it always
2288	   necessary to erase the WHOLE sector. If something goes
2289	   wrong before the contents has been restored from a copy in
2290	   RAM, your target system will be dead.
2291
2292	- CONFIG_ENV_ADDR_REDUND
2293	  CONFIG_ENV_SIZE_REDUND
2294
2295	   These settings describe a second storage area used to hold
2296	   a redundant copy of the environment data, so that there is
2297	   a valid backup copy in case there is a power failure during
2298	   a "saveenv" operation.
2299
2300BE CAREFUL! Any changes to the flash layout, and some changes to the
2301source code will make it necessary to adapt <board>/u-boot.lds*
2302accordingly!
2303
2304
2305- CONFIG_ENV_IS_IN_NVRAM:
2306
2307	Define this if you have some non-volatile memory device
2308	(NVRAM, battery buffered SRAM) which you want to use for the
2309	environment.
2310
2311	- CONFIG_ENV_ADDR:
2312	- CONFIG_ENV_SIZE:
2313
2314	  These two #defines are used to determine the memory area you
2315	  want to use for environment. It is assumed that this memory
2316	  can just be read and written to, without any special
2317	  provision.
2318
2319BE CAREFUL! The first access to the environment happens quite early
2320in U-Boot initalization (when we try to get the setting of for the
2321console baudrate). You *MUST* have mapped your NVRAM area then, or
2322U-Boot will hang.
2323
2324Please note that even with NVRAM we still use a copy of the
2325environment in RAM: we could work on NVRAM directly, but we want to
2326keep settings there always unmodified except somebody uses "saveenv"
2327to save the current settings.
2328
2329
2330- CONFIG_ENV_IS_IN_EEPROM:
2331
2332	Use this if you have an EEPROM or similar serial access
2333	device and a driver for it.
2334
2335	- CONFIG_ENV_OFFSET:
2336	- CONFIG_ENV_SIZE:
2337
2338	  These two #defines specify the offset and size of the
2339	  environment area within the total memory of your EEPROM.
2340
2341	- CONFIG_SYS_I2C_EEPROM_ADDR:
2342	  If defined, specified the chip address of the EEPROM device.
2343	  The default address is zero.
2344
2345	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
2346	  If defined, the number of bits used to address bytes in a
2347	  single page in the EEPROM device.  A 64 byte page, for example
2348	  would require six bits.
2349
2350	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
2351	  If defined, the number of milliseconds to delay between
2352	  page writes.	The default is zero milliseconds.
2353
2354	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
2355	  The length in bytes of the EEPROM memory array address.  Note
2356	  that this is NOT the chip address length!
2357
2358	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
2359	  EEPROM chips that implement "address overflow" are ones
2360	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
2361	  address and the extra bits end up in the "chip address" bit
2362	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
2363	  byte chips.
2364
2365	  Note that we consider the length of the address field to
2366	  still be one byte because the extra address bits are hidden
2367	  in the chip address.
2368
2369	- CONFIG_SYS_EEPROM_SIZE:
2370	  The size in bytes of the EEPROM device.
2371
2372
2373- CONFIG_ENV_IS_IN_DATAFLASH:
2374
2375	Define this if you have a DataFlash memory device which you
2376	want to use for the environment.
2377
2378	- CONFIG_ENV_OFFSET:
2379	- CONFIG_ENV_ADDR:
2380	- CONFIG_ENV_SIZE:
2381
2382	  These three #defines specify the offset and size of the
2383	  environment area within the total memory of your DataFlash placed
2384	  at the specified address.
2385
2386- CONFIG_ENV_IS_IN_NAND:
2387
2388	Define this if you have a NAND device which you want to use
2389	for the environment.
2390
2391	- CONFIG_ENV_OFFSET:
2392	- CONFIG_ENV_SIZE:
2393
2394	  These two #defines specify the offset and size of the environment
2395	  area within the first NAND device.
2396
2397	- CONFIG_ENV_OFFSET_REDUND
2398
2399	  This setting describes a second storage area of CONFIG_ENV_SIZE
2400	  size used to hold a redundant copy of the environment data,
2401	  so that there is a valid backup copy in case there is a
2402	  power failure during a "saveenv" operation.
2403
2404	Note: CONFIG_ENV_OFFSET and CONFIG_ENV_OFFSET_REDUND must be aligned
2405	to a block boundary, and CONFIG_ENV_SIZE must be a multiple of
2406	the NAND devices block size.
2407
2408- CONFIG_SYS_SPI_INIT_OFFSET
2409
2410	Defines offset to the initial SPI buffer area in DPRAM. The
2411	area is used at an early stage (ROM part) if the environment
2412	is configured to reside in the SPI EEPROM: We need a 520 byte
2413	scratch DPRAM area. It is used between the two initialization
2414	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
2415	to be a good choice since it makes it far enough from the
2416	start of the data area as well as from the stack pointer.
2417
2418Please note that the environment is read-only until the monitor
2419has been relocated to RAM and a RAM copy of the environment has been
2420created; also, when using EEPROM you will have to use getenv_r()
2421until then to read environment variables.
2422
2423The environment is protected by a CRC32 checksum. Before the monitor
2424is relocated into RAM, as a result of a bad CRC you will be working
2425with the compiled-in default environment - *silently*!!! [This is
2426necessary, because the first environment variable we need is the
2427"baudrate" setting for the console - if we have a bad CRC, we don't
2428have any device yet where we could complain.]
2429
2430Note: once the monitor has been relocated, then it will complain if
2431the default environment is used; a new CRC is computed as soon as you
2432use the "saveenv" command to store a valid environment.
2433
2434- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2435		Echo the inverted Ethernet link state to the fault LED.
2436
2437		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2438		      also needs to be defined.
2439
2440- CONFIG_SYS_FAULT_MII_ADDR:
2441		MII address of the PHY to check for the Ethernet link state.
2442
2443- CONFIG_SYS_64BIT_VSPRINTF:
2444		Makes vsprintf (and all *printf functions) support printing
2445		of 64bit values by using the L quantifier
2446
2447- CONFIG_SYS_64BIT_STRTOUL:
2448		Adds simple_strtoull that returns a 64bit value
2449
2450Low Level (hardware related) configuration options:
2451---------------------------------------------------
2452
2453- CONFIG_SYS_CACHELINE_SIZE:
2454		Cache Line Size of the CPU.
2455
2456- CONFIG_SYS_DEFAULT_IMMR:
2457		Default address of the IMMR after system reset.
2458
2459		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
2460		and RPXsuper) to be able to adjust the position of
2461		the IMMR register after a reset.
2462
2463- Floppy Disk Support:
2464		CONFIG_SYS_FDC_DRIVE_NUMBER
2465
2466		the default drive number (default value 0)
2467
2468		CONFIG_SYS_ISA_IO_STRIDE
2469
2470		defines the spacing between FDC chipset registers
2471		(default value 1)
2472
2473		CONFIG_SYS_ISA_IO_OFFSET
2474
2475		defines the offset of register from address. It
2476		depends on which part of the data bus is connected to
2477		the FDC chipset. (default value 0)
2478
2479		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
2480		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
2481		default value.
2482
2483		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
2484		fdc_hw_init() is called at the beginning of the FDC
2485		setup. fdc_hw_init() must be provided by the board
2486		source code. It is used to make hardware dependant
2487		initializations.
2488
2489- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
2490		DO NOT CHANGE unless you know exactly what you're
2491		doing! (11-4) [MPC8xx/82xx systems only]
2492
2493- CONFIG_SYS_INIT_RAM_ADDR:
2494
2495		Start address of memory area that can be used for
2496		initial data and stack; please note that this must be
2497		writable memory that is working WITHOUT special
2498		initialization, i. e. you CANNOT use normal RAM which
2499		will become available only after programming the
2500		memory controller and running certain initialization
2501		sequences.
2502
2503		U-Boot uses the following memory types:
2504		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
2505		- MPC824X: data cache
2506		- PPC4xx:  data cache
2507
2508- CONFIG_SYS_GBL_DATA_OFFSET:
2509
2510		Offset of the initial data structure in the memory
2511		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2512		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2513		data is located at the end of the available space
2514		(sometimes written as (CONFIG_SYS_INIT_RAM_END -
2515		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
2516		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2517		CONFIG_SYS_GBL_DATA_OFFSET) downward.
2518
2519	Note:
2520		On the MPC824X (or other systems that use the data
2521		cache for initial memory) the address chosen for
2522		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2523		point to an otherwise UNUSED address space between
2524		the top of RAM and the start of the PCI space.
2525
2526- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
2527
2528- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
2529
2530- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
2531
2532- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
2533
2534- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
2535
2536- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
2537
2538- CONFIG_SYS_OR_TIMING_SDRAM:
2539		SDRAM timing
2540
2541- CONFIG_SYS_MAMR_PTA:
2542		periodic timer for refresh
2543
2544- CONFIG_SYS_DER:	Debug Event Register (37-47)
2545
2546- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
2547  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
2548  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
2549  CONFIG_SYS_BR1_PRELIM:
2550		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2551
2552- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2553  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
2554  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
2555		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2556
2557- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
2558  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
2559		Machine Mode Register and Memory Periodic Timer
2560		Prescaler definitions (SDRAM timing)
2561
2562- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
2563		enable I2C microcode relocation patch (MPC8xx);
2564		define relocation offset in DPRAM [DSP2]
2565
2566- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
2567		enable SMC microcode relocation patch (MPC8xx);
2568		define relocation offset in DPRAM [SMC1]
2569
2570- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
2571		enable SPI microcode relocation patch (MPC8xx);
2572		define relocation offset in DPRAM [SCC4]
2573
2574- CONFIG_SYS_USE_OSCCLK:
2575		Use OSCM clock mode on MBX8xx board. Be careful,
2576		wrong setting might damage your board. Read
2577		doc/README.MBX before setting this variable!
2578
2579- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
2580		Offset of the bootmode word in DPRAM used by post
2581		(Power On Self Tests). This definition overrides
2582		#define'd default value in commproc.h resp.
2583		cpm_8260.h.
2584
2585- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
2586  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
2587  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
2588  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
2589  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
2590  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
2591  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
2592  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
2593		Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
2594
2595- CONFIG_SPD_EEPROM
2596		Get DDR timing information from an I2C EEPROM. Common
2597		with pluggable memory modules such as SODIMMs
2598
2599  SPD_EEPROM_ADDRESS
2600		I2C address of the SPD EEPROM
2601
2602- CONFIG_SYS_SPD_BUS_NUM
2603		If SPD EEPROM is on an I2C bus other than the first
2604		one, specify here. Note that the value must resolve
2605		to something your driver can deal with.
2606
2607- CONFIG_SYS_83XX_DDR_USES_CS0
2608		Only for 83xx systems. If specified, then DDR should
2609		be configured using CS0 and CS1 instead of CS2 and CS3.
2610
2611- CONFIG_SYS_83XX_DDR_USES_CS0
2612		Only for 83xx systems. If specified, then DDR should
2613		be configured using CS0 and CS1 instead of CS2 and CS3.
2614
2615- CONFIG_ETHER_ON_FEC[12]
2616		Define to enable FEC[12] on a 8xx series processor.
2617
2618- CONFIG_FEC[12]_PHY
2619		Define to the hardcoded PHY address which corresponds
2620		to the given FEC; i. e.
2621			#define CONFIG_FEC1_PHY 4
2622		means that the PHY with address 4 is connected to FEC1
2623
2624		When set to -1, means to probe for first available.
2625
2626- CONFIG_FEC[12]_PHY_NORXERR
2627		The PHY does not have a RXERR line (RMII only).
2628		(so program the FEC to ignore it).
2629
2630- CONFIG_RMII
2631		Enable RMII mode for all FECs.
2632		Note that this is a global option, we can't
2633		have one FEC in standard MII mode and another in RMII mode.
2634
2635- CONFIG_CRC32_VERIFY
2636		Add a verify option to the crc32 command.
2637		The syntax is:
2638
2639		=> crc32 -v <address> <count> <crc32>
2640
2641		Where address/count indicate a memory area
2642		and crc32 is the correct crc32 which the
2643		area should have.
2644
2645- CONFIG_LOOPW
2646		Add the "loopw" memory command. This only takes effect if
2647		the memory commands are activated globally (CONFIG_CMD_MEM).
2648
2649- CONFIG_MX_CYCLIC
2650		Add the "mdc" and "mwc" memory commands. These are cyclic
2651		"md/mw" commands.
2652		Examples:
2653
2654		=> mdc.b 10 4 500
2655		This command will print 4 bytes (10,11,12,13) each 500 ms.
2656
2657		=> mwc.l 100 12345678 10
2658		This command will write 12345678 to address 100 all 10 ms.
2659
2660		This only takes effect if the memory commands are activated
2661		globally (CONFIG_CMD_MEM).
2662
2663- CONFIG_SKIP_LOWLEVEL_INIT
2664- CONFIG_SKIP_RELOCATE_UBOOT
2665
2666		[ARM only] If these variables are defined, then
2667		certain low level initializations (like setting up
2668		the memory controller) are omitted and/or U-Boot does
2669		not relocate itself into RAM.
2670		Normally these variables MUST NOT be defined. The
2671		only exception is when U-Boot is loaded (to RAM) by
2672		some other boot loader or by a debugger which
2673		performs these initializations itself.
2674
2675
2676Building the Software:
2677======================
2678
2679Building U-Boot has been tested in several native build environments
2680and in many different cross environments. Of course we cannot support
2681all possibly existing versions of cross development tools in all
2682(potentially obsolete) versions. In case of tool chain problems we
2683recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
2684which is extensively used to build and test U-Boot.
2685
2686If you are not using a native environment, it is assumed that you
2687have GNU cross compiling tools available in your path. In this case,
2688you must set the environment variable CROSS_COMPILE in your shell.
2689Note that no changes to the Makefile or any other source files are
2690necessary. For example using the ELDK on a 4xx CPU, please enter:
2691
2692	$ CROSS_COMPILE=ppc_4xx-
2693	$ export CROSS_COMPILE
2694
2695U-Boot is intended to be simple to build. After installing the
2696sources you must configure U-Boot for one specific board type. This
2697is done by typing:
2698
2699	make NAME_config
2700
2701where "NAME_config" is the name of one of the existing configu-
2702rations; see the main Makefile for supported names.
2703
2704Note: for some board special configuration names may exist; check if
2705      additional information is available from the board vendor; for
2706      instance, the TQM823L systems are available without (standard)
2707      or with LCD support. You can select such additional "features"
2708      when choosing the configuration, i. e.
2709
2710      make TQM823L_config
2711	- will configure for a plain TQM823L, i. e. no LCD support
2712
2713      make TQM823L_LCD_config
2714	- will configure for a TQM823L with U-Boot console on LCD
2715
2716      etc.
2717
2718
2719Finally, type "make all", and you should get some working U-Boot
2720images ready for download to / installation on your system:
2721
2722- "u-boot.bin" is a raw binary image
2723- "u-boot" is an image in ELF binary format
2724- "u-boot.srec" is in Motorola S-Record format
2725
2726By default the build is performed locally and the objects are saved
2727in the source directory. One of the two methods can be used to change
2728this behavior and build U-Boot to some external directory:
2729
27301. Add O= to the make command line invocations:
2731
2732	make O=/tmp/build distclean
2733	make O=/tmp/build NAME_config
2734	make O=/tmp/build all
2735
27362. Set environment variable BUILD_DIR to point to the desired location:
2737
2738	export BUILD_DIR=/tmp/build
2739	make distclean
2740	make NAME_config
2741	make all
2742
2743Note that the command line "O=" setting overrides the BUILD_DIR environment
2744variable.
2745
2746
2747Please be aware that the Makefiles assume you are using GNU make, so
2748for instance on NetBSD you might need to use "gmake" instead of
2749native "make".
2750
2751
2752If the system board that you have is not listed, then you will need
2753to port U-Boot to your hardware platform. To do this, follow these
2754steps:
2755
27561.  Add a new configuration option for your board to the toplevel
2757    "Makefile" and to the "MAKEALL" script, using the existing
2758    entries as examples. Note that here and at many other places
2759    boards and other names are listed in alphabetical sort order. Please
2760    keep this order.
27612.  Create a new directory to hold your board specific code. Add any
2762    files you need. In your board directory, you will need at least
2763    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
27643.  Create a new configuration file "include/configs/<board>.h" for
2765    your board
27663.  If you're porting U-Boot to a new CPU, then also create a new
2767    directory to hold your CPU specific code. Add any files you need.
27684.  Run "make <board>_config" with your new name.
27695.  Type "make", and you should get a working "u-boot.srec" file
2770    to be installed on your target system.
27716.  Debug and solve any problems that might arise.
2772    [Of course, this last step is much harder than it sounds.]
2773
2774
2775Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2776==============================================================
2777
2778If you have modified U-Boot sources (for instance added a new board
2779or support for new devices, a new CPU, etc.) you are expected to
2780provide feedback to the other developers. The feedback normally takes
2781the form of a "patch", i. e. a context diff against a certain (latest
2782official or latest in the git repository) version of U-Boot sources.
2783
2784But before you submit such a patch, please verify that your modifi-
2785cation did not break existing code. At least make sure that *ALL* of
2786the supported boards compile WITHOUT ANY compiler warnings. To do so,
2787just run the "MAKEALL" script, which will configure and build U-Boot
2788for ALL supported system. Be warned, this will take a while. You can
2789select which (cross) compiler to use by passing a `CROSS_COMPILE'
2790environment variable to the script, i. e. to use the ELDK cross tools
2791you can type
2792
2793	CROSS_COMPILE=ppc_8xx- MAKEALL
2794
2795or to build on a native PowerPC system you can type
2796
2797	CROSS_COMPILE=' ' MAKEALL
2798
2799When using the MAKEALL script, the default behaviour is to build
2800U-Boot in the source directory. This location can be changed by
2801setting the BUILD_DIR environment variable. Also, for each target
2802built, the MAKEALL script saves two log files (<target>.ERR and
2803<target>.MAKEALL) in the <source dir>/LOG directory. This default
2804location can be changed by setting the MAKEALL_LOGDIR environment
2805variable. For example:
2806
2807	export BUILD_DIR=/tmp/build
2808	export MAKEALL_LOGDIR=/tmp/log
2809	CROSS_COMPILE=ppc_8xx- MAKEALL
2810
2811With the above settings build objects are saved in the /tmp/build,
2812log files are saved in the /tmp/log and the source tree remains clean
2813during the whole build process.
2814
2815
2816See also "U-Boot Porting Guide" below.
2817
2818
2819Monitor Commands - Overview:
2820============================
2821
2822go	- start application at address 'addr'
2823run	- run commands in an environment variable
2824bootm	- boot application image from memory
2825bootp	- boot image via network using BootP/TFTP protocol
2826tftpboot- boot image via network using TFTP protocol
2827	       and env variables "ipaddr" and "serverip"
2828	       (and eventually "gatewayip")
2829rarpboot- boot image via network using RARP/TFTP protocol
2830diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
2831loads	- load S-Record file over serial line
2832loadb	- load binary file over serial line (kermit mode)
2833md	- memory display
2834mm	- memory modify (auto-incrementing)
2835nm	- memory modify (constant address)
2836mw	- memory write (fill)
2837cp	- memory copy
2838cmp	- memory compare
2839crc32	- checksum calculation
2840imd	- i2c memory display
2841imm	- i2c memory modify (auto-incrementing)
2842inm	- i2c memory modify (constant address)
2843imw	- i2c memory write (fill)
2844icrc32	- i2c checksum calculation
2845iprobe	- probe to discover valid I2C chip addresses
2846iloop	- infinite loop on address range
2847isdram	- print SDRAM configuration information
2848sspi	- SPI utility commands
2849base	- print or set address offset
2850printenv- print environment variables
2851setenv	- set environment variables
2852saveenv - save environment variables to persistent storage
2853protect - enable or disable FLASH write protection
2854erase	- erase FLASH memory
2855flinfo	- print FLASH memory information
2856bdinfo	- print Board Info structure
2857iminfo	- print header information for application image
2858coninfo - print console devices and informations
2859ide	- IDE sub-system
2860loop	- infinite loop on address range
2861loopw	- infinite write loop on address range
2862mtest	- simple RAM test
2863icache	- enable or disable instruction cache
2864dcache	- enable or disable data cache
2865reset	- Perform RESET of the CPU
2866echo	- echo args to console
2867version - print monitor version
2868help	- print online help
2869?	- alias for 'help'
2870
2871
2872Monitor Commands - Detailed Description:
2873========================================
2874
2875TODO.
2876
2877For now: just type "help <command>".
2878
2879
2880Environment Variables:
2881======================
2882
2883U-Boot supports user configuration using Environment Variables which
2884can be made persistent by saving to Flash memory.
2885
2886Environment Variables are set using "setenv", printed using
2887"printenv", and saved to Flash using "saveenv". Using "setenv"
2888without a value can be used to delete a variable from the
2889environment. As long as you don't save the environment you are
2890working with an in-memory copy. In case the Flash area containing the
2891environment is erased by accident, a default environment is provided.
2892
2893Some configuration options can be set using Environment Variables:
2894
2895  baudrate	- see CONFIG_BAUDRATE
2896
2897  bootdelay	- see CONFIG_BOOTDELAY
2898
2899  bootcmd	- see CONFIG_BOOTCOMMAND
2900
2901  bootargs	- Boot arguments when booting an RTOS image
2902
2903  bootfile	- Name of the image to load with TFTP
2904
2905  bootm_low	- Memory range available for image processing in the bootm
2906		  command can be restricted. This variable is given as
2907		  a hexadecimal number and defines lowest address allowed
2908		  for use by the bootm command. See also "bootm_size"
2909		  environment variable. Address defined by "bootm_low" is
2910		  also the base of the initial memory mapping for the Linux
2911		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ.
2912
2913  bootm_size	- Memory range available for image processing in the bootm
2914		  command can be restricted. This variable is given as
2915		  a hexadecimal number and defines the size of the region
2916		  allowed for use by the bootm command. See also "bootm_low"
2917		  environment variable.
2918
2919  updatefile	- Location of the software update file on a TFTP server, used
2920		  by the automatic software update feature. Please refer to
2921		  documentation in doc/README.update for more details.
2922
2923  autoload	- if set to "no" (any string beginning with 'n'),
2924		  "bootp" will just load perform a lookup of the
2925		  configuration from the BOOTP server, but not try to
2926		  load any image using TFTP
2927
2928  autoscript	- if set to "yes" commands like "loadb", "loady",
2929		  "bootp", "tftpb", "rarpboot" and "nfs" will attempt
2930		  to automatically run script images (by internally
2931		  calling "autoscript").
2932
2933  autoscript_uname - if script image is in a format (FIT) this
2934		     variable is used to get script subimage unit name.
2935
2936  autostart	- if set to "yes", an image loaded using the "bootp",
2937		  "rarpboot", "tftpboot" or "diskboot" commands will
2938		  be automatically started (by internally calling
2939		  "bootm")
2940
2941		  If set to "no", a standalone image passed to the
2942		  "bootm" command will be copied to the load address
2943		  (and eventually uncompressed), but NOT be started.
2944		  This can be used to load and uncompress arbitrary
2945		  data.
2946
2947  i2cfast	- (PPC405GP|PPC405EP only)
2948		  if set to 'y' configures Linux I2C driver for fast
2949		  mode (400kHZ). This environment variable is used in
2950		  initialization code. So, for changes to be effective
2951		  it must be saved and board must be reset.
2952
2953  initrd_high	- restrict positioning of initrd images:
2954		  If this variable is not set, initrd images will be
2955		  copied to the highest possible address in RAM; this
2956		  is usually what you want since it allows for
2957		  maximum initrd size. If for some reason you want to
2958		  make sure that the initrd image is loaded below the
2959		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
2960		  variable to a value of "no" or "off" or "0".
2961		  Alternatively, you can set it to a maximum upper
2962		  address to use (U-Boot will still check that it
2963		  does not overwrite the U-Boot stack and data).
2964
2965		  For instance, when you have a system with 16 MB
2966		  RAM, and want to reserve 4 MB from use by Linux,
2967		  you can do this by adding "mem=12M" to the value of
2968		  the "bootargs" variable. However, now you must make
2969		  sure that the initrd image is placed in the first
2970		  12 MB as well - this can be done with
2971
2972		  setenv initrd_high 00c00000
2973
2974		  If you set initrd_high to 0xFFFFFFFF, this is an
2975		  indication to U-Boot that all addresses are legal
2976		  for the Linux kernel, including addresses in flash
2977		  memory. In this case U-Boot will NOT COPY the
2978		  ramdisk at all. This may be useful to reduce the
2979		  boot time on your system, but requires that this
2980		  feature is supported by your Linux kernel.
2981
2982  ipaddr	- IP address; needed for tftpboot command
2983
2984  loadaddr	- Default load address for commands like "bootp",
2985		  "rarpboot", "tftpboot", "loadb" or "diskboot"
2986
2987  loads_echo	- see CONFIG_LOADS_ECHO
2988
2989  serverip	- TFTP server IP address; needed for tftpboot command
2990
2991  bootretry	- see CONFIG_BOOT_RETRY_TIME
2992
2993  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
2994
2995  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
2996
2997  ethprime	- When CONFIG_NET_MULTI is enabled controls which
2998		  interface is used first.
2999
3000  ethact	- When CONFIG_NET_MULTI is enabled controls which
3001		  interface is currently active. For example you
3002		  can do the following
3003
3004		  => setenv ethact FEC ETHERNET
3005		  => ping 192.168.0.1 # traffic sent on FEC ETHERNET
3006		  => setenv ethact SCC ETHERNET
3007		  => ping 10.0.0.1 # traffic sent on SCC ETHERNET
3008
3009  ethrotate	- When set to "no" U-Boot does not go through all
3010		  available network interfaces.
3011		  It just stays at the currently selected interface.
3012
3013   netretry	- When set to "no" each network operation will
3014		  either succeed or fail without retrying.
3015		  When set to "once" the network operation will
3016		  fail when all the available network interfaces
3017		  are tried once without success.
3018		  Useful on scripts which control the retry operation
3019		  themselves.
3020
3021  npe_ucode	- see CONFIG_IXP4XX_NPE_EXT_UCOD
3022		  if set load address for the NPE microcode
3023
3024  tftpsrcport	- If this is set, the value is used for TFTP's
3025		  UDP source port.
3026
3027  tftpdstport	- If this is set, the value is used for TFTP's UDP
3028		  destination port instead of the Well Know Port 69.
3029
3030   vlan		- When set to a value < 4095 the traffic over
3031		  Ethernet is encapsulated/received over 802.1q
3032		  VLAN tagged frames.
3033
3034The following environment variables may be used and automatically
3035updated by the network boot commands ("bootp" and "rarpboot"),
3036depending the information provided by your boot server:
3037
3038  bootfile	- see above
3039  dnsip		- IP address of your Domain Name Server
3040  dnsip2	- IP address of your secondary Domain Name Server
3041  gatewayip	- IP address of the Gateway (Router) to use
3042  hostname	- Target hostname
3043  ipaddr	- see above
3044  netmask	- Subnet Mask
3045  rootpath	- Pathname of the root filesystem on the NFS server
3046  serverip	- see above
3047
3048
3049There are two special Environment Variables:
3050
3051  serial#	- contains hardware identification information such
3052		  as type string and/or serial number
3053  ethaddr	- Ethernet address
3054
3055These variables can be set only once (usually during manufacturing of
3056the board). U-Boot refuses to delete or overwrite these variables
3057once they have been set once.
3058
3059
3060Further special Environment Variables:
3061
3062  ver		- Contains the U-Boot version string as printed
3063		  with the "version" command. This variable is
3064		  readonly (see CONFIG_VERSION_VARIABLE).
3065
3066
3067Please note that changes to some configuration parameters may take
3068only effect after the next boot (yes, that's just like Windoze :-).
3069
3070
3071Command Line Parsing:
3072=====================
3073
3074There are two different command line parsers available with U-Boot:
3075the old "simple" one, and the much more powerful "hush" shell:
3076
3077Old, simple command line parser:
3078--------------------------------
3079
3080- supports environment variables (through setenv / saveenv commands)
3081- several commands on one line, separated by ';'
3082- variable substitution using "... ${name} ..." syntax
3083- special characters ('$', ';') can be escaped by prefixing with '\',
3084  for example:
3085	setenv bootcmd bootm \${address}
3086- You can also escape text by enclosing in single apostrophes, for example:
3087	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
3088
3089Hush shell:
3090-----------
3091
3092- similar to Bourne shell, with control structures like
3093  if...then...else...fi, for...do...done; while...do...done,
3094  until...do...done, ...
3095- supports environment ("global") variables (through setenv / saveenv
3096  commands) and local shell variables (through standard shell syntax
3097  "name=value"); only environment variables can be used with "run"
3098  command
3099
3100General rules:
3101--------------
3102
3103(1) If a command line (or an environment variable executed by a "run"
3104    command) contains several commands separated by semicolon, and
3105    one of these commands fails, then the remaining commands will be
3106    executed anyway.
3107
3108(2) If you execute several variables with one call to run (i. e.
3109    calling run with a list of variables as arguments), any failing
3110    command will cause "run" to terminate, i. e. the remaining
3111    variables are not executed.
3112
3113Note for Redundant Ethernet Interfaces:
3114=======================================
3115
3116Some boards come with redundant Ethernet interfaces; U-Boot supports
3117such configurations and is capable of automatic selection of a
3118"working" interface when needed. MAC assignment works as follows:
3119
3120Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
3121MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
3122"eth1addr" (=>eth1), "eth2addr", ...
3123
3124If the network interface stores some valid MAC address (for instance
3125in SROM), this is used as default address if there is NO correspon-
3126ding setting in the environment; if the corresponding environment
3127variable is set, this overrides the settings in the card; that means:
3128
3129o If the SROM has a valid MAC address, and there is no address in the
3130  environment, the SROM's address is used.
3131
3132o If there is no valid address in the SROM, and a definition in the
3133  environment exists, then the value from the environment variable is
3134  used.
3135
3136o If both the SROM and the environment contain a MAC address, and
3137  both addresses are the same, this MAC address is used.
3138
3139o If both the SROM and the environment contain a MAC address, and the
3140  addresses differ, the value from the environment is used and a
3141  warning is printed.
3142
3143o If neither SROM nor the environment contain a MAC address, an error
3144  is raised.
3145
3146
3147Image Formats:
3148==============
3149
3150U-Boot is capable of booting (and performing other auxiliary operations on)
3151images in two formats:
3152
3153New uImage format (FIT)
3154-----------------------
3155
3156Flexible and powerful format based on Flattened Image Tree -- FIT (similar
3157to Flattened Device Tree). It allows the use of images with multiple
3158components (several kernels, ramdisks, etc.), with contents protected by
3159SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
3160
3161
3162Old uImage format
3163-----------------
3164
3165Old image format is based on binary files which can be basically anything,
3166preceded by a special header; see the definitions in include/image.h for
3167details; basically, the header defines the following image properties:
3168
3169* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
3170  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
3171  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
3172  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
3173  INTEGRITY).
3174* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
3175  IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
3176  Currently supported: ARM, AVR32, Intel x86, MIPS, NIOS, PowerPC).
3177* Compression Type (uncompressed, gzip, bzip2)
3178* Load Address
3179* Entry Point
3180* Image Name
3181* Image Timestamp
3182
3183The header is marked by a special Magic Number, and both the header
3184and the data portions of the image are secured against corruption by
3185CRC32 checksums.
3186
3187
3188Linux Support:
3189==============
3190
3191Although U-Boot should support any OS or standalone application
3192easily, the main focus has always been on Linux during the design of
3193U-Boot.
3194
3195U-Boot includes many features that so far have been part of some
3196special "boot loader" code within the Linux kernel. Also, any
3197"initrd" images to be used are no longer part of one big Linux image;
3198instead, kernel and "initrd" are separate images. This implementation
3199serves several purposes:
3200
3201- the same features can be used for other OS or standalone
3202  applications (for instance: using compressed images to reduce the
3203  Flash memory footprint)
3204
3205- it becomes much easier to port new Linux kernel versions because
3206  lots of low-level, hardware dependent stuff are done by U-Boot
3207
3208- the same Linux kernel image can now be used with different "initrd"
3209  images; of course this also means that different kernel images can
3210  be run with the same "initrd". This makes testing easier (you don't
3211  have to build a new "zImage.initrd" Linux image when you just
3212  change a file in your "initrd"). Also, a field-upgrade of the
3213  software is easier now.
3214
3215
3216Linux HOWTO:
3217============
3218
3219Porting Linux to U-Boot based systems:
3220---------------------------------------
3221
3222U-Boot cannot save you from doing all the necessary modifications to
3223configure the Linux device drivers for use with your target hardware
3224(no, we don't intend to provide a full virtual machine interface to
3225Linux :-).
3226
3227But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
3228
3229Just make sure your machine specific header file (for instance
3230include/asm-ppc/tqm8xx.h) includes the same definition of the Board
3231Information structure as we define in include/asm-<arch>/u-boot.h,
3232and make sure that your definition of IMAP_ADDR uses the same value
3233as your U-Boot configuration in CONFIG_SYS_IMMR.
3234
3235
3236Configuring the Linux kernel:
3237-----------------------------
3238
3239No specific requirements for U-Boot. Make sure you have some root
3240device (initial ramdisk, NFS) for your target system.
3241
3242
3243Building a Linux Image:
3244-----------------------
3245
3246With U-Boot, "normal" build targets like "zImage" or "bzImage" are
3247not used. If you use recent kernel source, a new build target
3248"uImage" will exist which automatically builds an image usable by
3249U-Boot. Most older kernels also have support for a "pImage" target,
3250which was introduced for our predecessor project PPCBoot and uses a
3251100% compatible format.
3252
3253Example:
3254
3255	make TQM850L_config
3256	make oldconfig
3257	make dep
3258	make uImage
3259
3260The "uImage" build target uses a special tool (in 'tools/mkimage') to
3261encapsulate a compressed Linux kernel image with header	 information,
3262CRC32 checksum etc. for use with U-Boot. This is what we are doing:
3263
3264* build a standard "vmlinux" kernel image (in ELF binary format):
3265
3266* convert the kernel into a raw binary image:
3267
3268	${CROSS_COMPILE}-objcopy -O binary \
3269				 -R .note -R .comment \
3270				 -S vmlinux linux.bin
3271
3272* compress the binary image:
3273
3274	gzip -9 linux.bin
3275
3276* package compressed binary image for U-Boot:
3277
3278	mkimage -A ppc -O linux -T kernel -C gzip \
3279		-a 0 -e 0 -n "Linux Kernel Image" \
3280		-d linux.bin.gz uImage
3281
3282
3283The "mkimage" tool can also be used to create ramdisk images for use
3284with U-Boot, either separated from the Linux kernel image, or
3285combined into one file. "mkimage" encapsulates the images with a 64
3286byte header containing information about target architecture,
3287operating system, image type, compression method, entry points, time
3288stamp, CRC32 checksums, etc.
3289
3290"mkimage" can be called in two ways: to verify existing images and
3291print the header information, or to build new images.
3292
3293In the first form (with "-l" option) mkimage lists the information
3294contained in the header of an existing U-Boot image; this includes
3295checksum verification:
3296
3297	tools/mkimage -l image
3298	  -l ==> list image header information
3299
3300The second form (with "-d" option) is used to build a U-Boot image
3301from a "data file" which is used as image payload:
3302
3303	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3304		      -n name -d data_file image
3305	  -A ==> set architecture to 'arch'
3306	  -O ==> set operating system to 'os'
3307	  -T ==> set image type to 'type'
3308	  -C ==> set compression type 'comp'
3309	  -a ==> set load address to 'addr' (hex)
3310	  -e ==> set entry point to 'ep' (hex)
3311	  -n ==> set image name to 'name'
3312	  -d ==> use image data from 'datafile'
3313
3314Right now, all Linux kernels for PowerPC systems use the same load
3315address (0x00000000), but the entry point address depends on the
3316kernel version:
3317
3318- 2.2.x kernels have the entry point at 0x0000000C,
3319- 2.3.x and later kernels have the entry point at 0x00000000.
3320
3321So a typical call to build a U-Boot image would read:
3322
3323	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3324	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3325	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
3326	> examples/uImage.TQM850L
3327	Image Name:   2.4.4 kernel for TQM850L
3328	Created:      Wed Jul 19 02:34:59 2000
3329	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3330	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
3331	Load Address: 0x00000000
3332	Entry Point:  0x00000000
3333
3334To verify the contents of the image (or check for corruption):
3335
3336	-> tools/mkimage -l examples/uImage.TQM850L
3337	Image Name:   2.4.4 kernel for TQM850L
3338	Created:      Wed Jul 19 02:34:59 2000
3339	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3340	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
3341	Load Address: 0x00000000
3342	Entry Point:  0x00000000
3343
3344NOTE: for embedded systems where boot time is critical you can trade
3345speed for memory and install an UNCOMPRESSED image instead: this
3346needs more space in Flash, but boots much faster since it does not
3347need to be uncompressed:
3348
3349	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
3350	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3351	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3352	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
3353	> examples/uImage.TQM850L-uncompressed
3354	Image Name:   2.4.4 kernel for TQM850L
3355	Created:      Wed Jul 19 02:34:59 2000
3356	Image Type:   PowerPC Linux Kernel Image (uncompressed)
3357	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
3358	Load Address: 0x00000000
3359	Entry Point:  0x00000000
3360
3361
3362Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3363when your kernel is intended to use an initial ramdisk:
3364
3365	-> tools/mkimage -n 'Simple Ramdisk Image' \
3366	> -A ppc -O linux -T ramdisk -C gzip \
3367	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3368	Image Name:   Simple Ramdisk Image
3369	Created:      Wed Jan 12 14:01:50 2000
3370	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
3371	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
3372	Load Address: 0x00000000
3373	Entry Point:  0x00000000
3374
3375
3376Installing a Linux Image:
3377-------------------------
3378
3379To downloading a U-Boot image over the serial (console) interface,
3380you must convert the image to S-Record format:
3381
3382	objcopy -I binary -O srec examples/image examples/image.srec
3383
3384The 'objcopy' does not understand the information in the U-Boot
3385image header, so the resulting S-Record file will be relative to
3386address 0x00000000. To load it to a given address, you need to
3387specify the target address as 'offset' parameter with the 'loads'
3388command.
3389
3390Example: install the image to address 0x40100000 (which on the
3391TQM8xxL is in the first Flash bank):
3392
3393	=> erase 40100000 401FFFFF
3394
3395	.......... done
3396	Erased 8 sectors
3397
3398	=> loads 40100000
3399	## Ready for S-Record download ...
3400	~>examples/image.srec
3401	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3402	...
3403	15989 15990 15991 15992
3404	[file transfer complete]
3405	[connected]
3406	## Start Addr = 0x00000000
3407
3408
3409You can check the success of the download using the 'iminfo' command;
3410this includes a checksum verification so you can be sure no data
3411corruption happened:
3412
3413	=> imi 40100000
3414
3415	## Checking Image at 40100000 ...
3416	   Image Name:	 2.2.13 for initrd on TQM850L
3417	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3418	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3419	   Load Address: 00000000
3420	   Entry Point:	 0000000c
3421	   Verifying Checksum ... OK
3422
3423
3424Boot Linux:
3425-----------
3426
3427The "bootm" command is used to boot an application that is stored in
3428memory (RAM or Flash). In case of a Linux kernel image, the contents
3429of the "bootargs" environment variable is passed to the kernel as
3430parameters. You can check and modify this variable using the
3431"printenv" and "setenv" commands:
3432
3433
3434	=> printenv bootargs
3435	bootargs=root=/dev/ram
3436
3437	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3438
3439	=> printenv bootargs
3440	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3441
3442	=> bootm 40020000
3443	## Booting Linux kernel at 40020000 ...
3444	   Image Name:	 2.2.13 for NFS on TQM850L
3445	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3446	   Data Size:	 381681 Bytes = 372 kB = 0 MB
3447	   Load Address: 00000000
3448	   Entry Point:	 0000000c
3449	   Verifying Checksum ... OK
3450	   Uncompressing Kernel Image ... OK
3451	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
3452	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3453	time_init: decrementer frequency = 187500000/60
3454	Calibrating delay loop... 49.77 BogoMIPS
3455	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3456	...
3457
3458If you want to boot a Linux kernel with initial RAM disk, you pass
3459the memory addresses of both the kernel and the initrd image (PPBCOOT
3460format!) to the "bootm" command:
3461
3462	=> imi 40100000 40200000
3463
3464	## Checking Image at 40100000 ...
3465	   Image Name:	 2.2.13 for initrd on TQM850L
3466	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3467	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3468	   Load Address: 00000000
3469	   Entry Point:	 0000000c
3470	   Verifying Checksum ... OK
3471
3472	## Checking Image at 40200000 ...
3473	   Image Name:	 Simple Ramdisk Image
3474	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3475	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3476	   Load Address: 00000000
3477	   Entry Point:	 00000000
3478	   Verifying Checksum ... OK
3479
3480	=> bootm 40100000 40200000
3481	## Booting Linux kernel at 40100000 ...
3482	   Image Name:	 2.2.13 for initrd on TQM850L
3483	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3484	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3485	   Load Address: 00000000
3486	   Entry Point:	 0000000c
3487	   Verifying Checksum ... OK
3488	   Uncompressing Kernel Image ... OK
3489	## Loading RAMDisk Image at 40200000 ...
3490	   Image Name:	 Simple Ramdisk Image
3491	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3492	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3493	   Load Address: 00000000
3494	   Entry Point:	 00000000
3495	   Verifying Checksum ... OK
3496	   Loading Ramdisk ... OK
3497	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
3498	Boot arguments: root=/dev/ram
3499	time_init: decrementer frequency = 187500000/60
3500	Calibrating delay loop... 49.77 BogoMIPS
3501	...
3502	RAMDISK: Compressed image found at block 0
3503	VFS: Mounted root (ext2 filesystem).
3504
3505	bash#
3506
3507Boot Linux and pass a flat device tree:
3508-----------
3509
3510First, U-Boot must be compiled with the appropriate defines. See the section
3511titled "Linux Kernel Interface" above for a more in depth explanation. The
3512following is an example of how to start a kernel and pass an updated
3513flat device tree:
3514
3515=> print oftaddr
3516oftaddr=0x300000
3517=> print oft
3518oft=oftrees/mpc8540ads.dtb
3519=> tftp $oftaddr $oft
3520Speed: 1000, full duplex
3521Using TSEC0 device
3522TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3523Filename 'oftrees/mpc8540ads.dtb'.
3524Load address: 0x300000
3525Loading: #
3526done
3527Bytes transferred = 4106 (100a hex)
3528=> tftp $loadaddr $bootfile
3529Speed: 1000, full duplex
3530Using TSEC0 device
3531TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3532Filename 'uImage'.
3533Load address: 0x200000
3534Loading:############
3535done
3536Bytes transferred = 1029407 (fb51f hex)
3537=> print loadaddr
3538loadaddr=200000
3539=> print oftaddr
3540oftaddr=0x300000
3541=> bootm $loadaddr - $oftaddr
3542## Booting image at 00200000 ...
3543   Image Name:	 Linux-2.6.17-dirty
3544   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3545   Data Size:	 1029343 Bytes = 1005.2 kB
3546   Load Address: 00000000
3547   Entry Point:	 00000000
3548   Verifying Checksum ... OK
3549   Uncompressing Kernel Image ... OK
3550Booting using flat device tree at 0x300000
3551Using MPC85xx ADS machine description
3552Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3553[snip]
3554
3555
3556More About U-Boot Image Types:
3557------------------------------
3558
3559U-Boot supports the following image types:
3560
3561   "Standalone Programs" are directly runnable in the environment
3562	provided by U-Boot; it is expected that (if they behave
3563	well) you can continue to work in U-Boot after return from
3564	the Standalone Program.
3565   "OS Kernel Images" are usually images of some Embedded OS which
3566	will take over control completely. Usually these programs
3567	will install their own set of exception handlers, device
3568	drivers, set up the MMU, etc. - this means, that you cannot
3569	expect to re-enter U-Boot except by resetting the CPU.
3570   "RAMDisk Images" are more or less just data blocks, and their
3571	parameters (address, size) are passed to an OS kernel that is
3572	being started.
3573   "Multi-File Images" contain several images, typically an OS
3574	(Linux) kernel image and one or more data images like
3575	RAMDisks. This construct is useful for instance when you want
3576	to boot over the network using BOOTP etc., where the boot
3577	server provides just a single image file, but you want to get
3578	for instance an OS kernel and a RAMDisk image.
3579
3580	"Multi-File Images" start with a list of image sizes, each
3581	image size (in bytes) specified by an "uint32_t" in network
3582	byte order. This list is terminated by an "(uint32_t)0".
3583	Immediately after the terminating 0 follow the images, one by
3584	one, all aligned on "uint32_t" boundaries (size rounded up to
3585	a multiple of 4 bytes).
3586
3587   "Firmware Images" are binary images containing firmware (like
3588	U-Boot or FPGA images) which usually will be programmed to
3589	flash memory.
3590
3591   "Script files" are command sequences that will be executed by
3592	U-Boot's command interpreter; this feature is especially
3593	useful when you configure U-Boot to use a real shell (hush)
3594	as command interpreter.
3595
3596
3597Standalone HOWTO:
3598=================
3599
3600One of the features of U-Boot is that you can dynamically load and
3601run "standalone" applications, which can use some resources of
3602U-Boot like console I/O functions or interrupt services.
3603
3604Two simple examples are included with the sources:
3605
3606"Hello World" Demo:
3607-------------------
3608
3609'examples/hello_world.c' contains a small "Hello World" Demo
3610application; it is automatically compiled when you build U-Boot.
3611It's configured to run at address 0x00040004, so you can play with it
3612like that:
3613
3614	=> loads
3615	## Ready for S-Record download ...
3616	~>examples/hello_world.srec
3617	1 2 3 4 5 6 7 8 9 10 11 ...
3618	[file transfer complete]
3619	[connected]
3620	## Start Addr = 0x00040004
3621
3622	=> go 40004 Hello World! This is a test.
3623	## Starting application at 0x00040004 ...
3624	Hello World
3625	argc = 7
3626	argv[0] = "40004"
3627	argv[1] = "Hello"
3628	argv[2] = "World!"
3629	argv[3] = "This"
3630	argv[4] = "is"
3631	argv[5] = "a"
3632	argv[6] = "test."
3633	argv[7] = "<NULL>"
3634	Hit any key to exit ...
3635
3636	## Application terminated, rc = 0x0
3637
3638Another example, which demonstrates how to register a CPM interrupt
3639handler with the U-Boot code, can be found in 'examples/timer.c'.
3640Here, a CPM timer is set up to generate an interrupt every second.
3641The interrupt service routine is trivial, just printing a '.'
3642character, but this is just a demo program. The application can be
3643controlled by the following keys:
3644
3645	? - print current values og the CPM Timer registers
3646	b - enable interrupts and start timer
3647	e - stop timer and disable interrupts
3648	q - quit application
3649
3650	=> loads
3651	## Ready for S-Record download ...
3652	~>examples/timer.srec
3653	1 2 3 4 5 6 7 8 9 10 11 ...
3654	[file transfer complete]
3655	[connected]
3656	## Start Addr = 0x00040004
3657
3658	=> go 40004
3659	## Starting application at 0x00040004 ...
3660	TIMERS=0xfff00980
3661	Using timer 1
3662	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3663
3664Hit 'b':
3665	[q, b, e, ?] Set interval 1000000 us
3666	Enabling timer
3667Hit '?':
3668	[q, b, e, ?] ........
3669	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3670Hit '?':
3671	[q, b, e, ?] .
3672	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3673Hit '?':
3674	[q, b, e, ?] .
3675	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3676Hit '?':
3677	[q, b, e, ?] .
3678	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3679Hit 'e':
3680	[q, b, e, ?] ...Stopping timer
3681Hit 'q':
3682	[q, b, e, ?] ## Application terminated, rc = 0x0
3683
3684
3685Minicom warning:
3686================
3687
3688Over time, many people have reported problems when trying to use the
3689"minicom" terminal emulation program for serial download. I (wd)
3690consider minicom to be broken, and recommend not to use it. Under
3691Unix, I recommend to use C-Kermit for general purpose use (and
3692especially for kermit binary protocol download ("loadb" command), and
3693use "cu" for S-Record download ("loads" command).
3694
3695Nevertheless, if you absolutely want to use it try adding this
3696configuration to your "File transfer protocols" section:
3697
3698	   Name	   Program			Name U/D FullScr IO-Red. Multi
3699	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
3700	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
3701
3702
3703NetBSD Notes:
3704=============
3705
3706Starting at version 0.9.2, U-Boot supports NetBSD both as host
3707(build U-Boot) and target system (boots NetBSD/mpc8xx).
3708
3709Building requires a cross environment; it is known to work on
3710NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3711need gmake since the Makefiles are not compatible with BSD make).
3712Note that the cross-powerpc package does not install include files;
3713attempting to build U-Boot will fail because <machine/ansi.h> is
3714missing.  This file has to be installed and patched manually:
3715
3716	# cd /usr/pkg/cross/powerpc-netbsd/include
3717	# mkdir powerpc
3718	# ln -s powerpc machine
3719	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3720	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
3721
3722Native builds *don't* work due to incompatibilities between native
3723and U-Boot include files.
3724
3725Booting assumes that (the first part of) the image booted is a
3726stage-2 loader which in turn loads and then invokes the kernel
3727proper. Loader sources will eventually appear in the NetBSD source
3728tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3729meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3730
3731
3732Implementation Internals:
3733=========================
3734
3735The following is not intended to be a complete description of every
3736implementation detail. However, it should help to understand the
3737inner workings of U-Boot and make it easier to port it to custom
3738hardware.
3739
3740
3741Initial Stack, Global Data:
3742---------------------------
3743
3744The implementation of U-Boot is complicated by the fact that U-Boot
3745starts running out of ROM (flash memory), usually without access to
3746system RAM (because the memory controller is not initialized yet).
3747This means that we don't have writable Data or BSS segments, and BSS
3748is not initialized as zero. To be able to get a C environment working
3749at all, we have to allocate at least a minimal stack. Implementation
3750options for this are defined and restricted by the CPU used: Some CPU
3751models provide on-chip memory (like the IMMR area on MPC8xx and
3752MPC826x processors), on others (parts of) the data cache can be
3753locked as (mis-) used as memory, etc.
3754
3755	Chris Hallinan posted a good summary of these issues to the
3756	U-Boot mailing list:
3757
3758	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3759	From: "Chris Hallinan" <clh@net1plus.com>
3760	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3761	...
3762
3763	Correct me if I'm wrong, folks, but the way I understand it
3764	is this: Using DCACHE as initial RAM for Stack, etc, does not
3765	require any physical RAM backing up the cache. The cleverness
3766	is that the cache is being used as a temporary supply of
3767	necessary storage before the SDRAM controller is setup. It's
3768	beyond the scope of this list to explain the details, but you
3769	can see how this works by studying the cache architecture and
3770	operation in the architecture and processor-specific manuals.
3771
3772	OCM is On Chip Memory, which I believe the 405GP has 4K. It
3773	is another option for the system designer to use as an
3774	initial stack/RAM area prior to SDRAM being available. Either
3775	option should work for you. Using CS 4 should be fine if your
3776	board designers haven't used it for something that would
3777	cause you grief during the initial boot! It is frequently not
3778	used.
3779
3780	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
3781	with your processor/board/system design. The default value
3782	you will find in any recent u-boot distribution in
3783	walnut.h should work for you. I'd set it to a value larger
3784	than your SDRAM module. If you have a 64MB SDRAM module, set
3785	it above 400_0000. Just make sure your board has no resources
3786	that are supposed to respond to that address! That code in
3787	start.S has been around a while and should work as is when
3788	you get the config right.
3789
3790	-Chris Hallinan
3791	DS4.COM, Inc.
3792
3793It is essential to remember this, since it has some impact on the C
3794code for the initialization procedures:
3795
3796* Initialized global data (data segment) is read-only. Do not attempt
3797  to write it.
3798
3799* Do not use any uninitialized global data (or implicitely initialized
3800  as zero data - BSS segment) at all - this is undefined, initiali-
3801  zation is performed later (when relocating to RAM).
3802
3803* Stack space is very limited. Avoid big data buffers or things like
3804  that.
3805
3806Having only the stack as writable memory limits means we cannot use
3807normal global data to share information beween the code. But it
3808turned out that the implementation of U-Boot can be greatly
3809simplified by making a global data structure (gd_t) available to all
3810functions. We could pass a pointer to this data as argument to _all_
3811functions, but this would bloat the code. Instead we use a feature of
3812the GCC compiler (Global Register Variables) to share the data: we
3813place a pointer (gd) to the global data into a register which we
3814reserve for this purpose.
3815
3816When choosing a register for such a purpose we are restricted by the
3817relevant  (E)ABI  specifications for the current architecture, and by
3818GCC's implementation.
3819
3820For PowerPC, the following registers have specific use:
3821	R1:	stack pointer
3822	R2:	reserved for system use
3823	R3-R4:	parameter passing and return values
3824	R5-R10: parameter passing
3825	R13:	small data area pointer
3826	R30:	GOT pointer
3827	R31:	frame pointer
3828
3829	(U-Boot also uses R14 as internal GOT pointer.)
3830
3831    ==> U-Boot will use R2 to hold a pointer to the global data
3832
3833    Note: on PPC, we could use a static initializer (since the
3834    address of the global data structure is known at compile time),
3835    but it turned out that reserving a register results in somewhat
3836    smaller code - although the code savings are not that big (on
3837    average for all boards 752 bytes for the whole U-Boot image,
3838    624 text + 127 data).
3839
3840On Blackfin, the normal C ABI (except for P5) is followed as documented here:
3841	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
3842
3843    ==> U-Boot will use P5 to hold a pointer to the global data
3844
3845On ARM, the following registers are used:
3846
3847	R0:	function argument word/integer result
3848	R1-R3:	function argument word
3849	R9:	GOT pointer
3850	R10:	stack limit (used only if stack checking if enabled)
3851	R11:	argument (frame) pointer
3852	R12:	temporary workspace
3853	R13:	stack pointer
3854	R14:	link register
3855	R15:	program counter
3856
3857    ==> U-Boot will use R8 to hold a pointer to the global data
3858
3859NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3860or current versions of GCC may "optimize" the code too much.
3861
3862Memory Management:
3863------------------
3864
3865U-Boot runs in system state and uses physical addresses, i.e. the
3866MMU is not used either for address mapping nor for memory protection.
3867
3868The available memory is mapped to fixed addresses using the memory
3869controller. In this process, a contiguous block is formed for each
3870memory type (Flash, SDRAM, SRAM), even when it consists of several
3871physical memory banks.
3872
3873U-Boot is installed in the first 128 kB of the first Flash bank (on
3874TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3875booting and sizing and initializing DRAM, the code relocates itself
3876to the upper end of DRAM. Immediately below the U-Boot code some
3877memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
3878configuration setting]. Below that, a structure with global Board
3879Info data is placed, followed by the stack (growing downward).
3880
3881Additionally, some exception handler code is copied to the low 8 kB
3882of DRAM (0x00000000 ... 0x00001FFF).
3883
3884So a typical memory configuration with 16 MB of DRAM could look like
3885this:
3886
3887	0x0000 0000	Exception Vector code
3888	      :
3889	0x0000 1FFF
3890	0x0000 2000	Free for Application Use
3891	      :
3892	      :
3893
3894	      :
3895	      :
3896	0x00FB FF20	Monitor Stack (Growing downward)
3897	0x00FB FFAC	Board Info Data and permanent copy of global data
3898	0x00FC 0000	Malloc Arena
3899	      :
3900	0x00FD FFFF
3901	0x00FE 0000	RAM Copy of Monitor Code
3902	...		eventually: LCD or video framebuffer
3903	...		eventually: pRAM (Protected RAM - unchanged by reset)
3904	0x00FF FFFF	[End of RAM]
3905
3906
3907System Initialization:
3908----------------------
3909
3910In the reset configuration, U-Boot starts at the reset entry point
3911(on most PowerPC systems at address 0x00000100). Because of the reset
3912configuration for CS0# this is a mirror of the onboard Flash memory.
3913To be able to re-map memory U-Boot then jumps to its link address.
3914To be able to implement the initialization code in C, a (small!)
3915initial stack is set up in the internal Dual Ported RAM (in case CPUs
3916which provide such a feature like MPC8xx or MPC8260), or in a locked
3917part of the data cache. After that, U-Boot initializes the CPU core,
3918the caches and the SIU.
3919
3920Next, all (potentially) available memory banks are mapped using a
3921preliminary mapping. For example, we put them on 512 MB boundaries
3922(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3923on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3924programmed for SDRAM access. Using the temporary configuration, a
3925simple memory test is run that determines the size of the SDRAM
3926banks.
3927
3928When there is more than one SDRAM bank, and the banks are of
3929different size, the largest is mapped first. For equal size, the first
3930bank (CS2#) is mapped first. The first mapping is always for address
39310x00000000, with any additional banks following immediately to create
3932contiguous memory starting from 0.
3933
3934Then, the monitor installs itself at the upper end of the SDRAM area
3935and allocates memory for use by malloc() and for the global Board
3936Info data; also, the exception vector code is copied to the low RAM
3937pages, and the final stack is set up.
3938
3939Only after this relocation will you have a "normal" C environment;
3940until that you are restricted in several ways, mostly because you are
3941running from ROM, and because the code will have to be relocated to a
3942new address in RAM.
3943
3944
3945U-Boot Porting Guide:
3946----------------------
3947
3948[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3949list, October 2002]
3950
3951
3952int main (int argc, char *argv[])
3953{
3954	sighandler_t no_more_time;
3955
3956	signal (SIGALRM, no_more_time);
3957	alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
3958
3959	if (available_money > available_manpower) {
3960		pay consultant to port U-Boot;
3961		return 0;
3962	}
3963
3964	Download latest U-Boot source;
3965
3966	Subscribe to u-boot mailing list;
3967
3968	if (clueless) {
3969		email ("Hi, I am new to U-Boot, how do I get started?");
3970	}
3971
3972	while (learning) {
3973		Read the README file in the top level directory;
3974		Read http://www.denx.de/twiki/bin/view/DULG/Manual ;
3975		Read the source, Luke;
3976	}
3977
3978	if (available_money > toLocalCurrency ($2500)) {
3979		Buy a BDI2000;
3980	} else {
3981		Add a lot of aggravation and time;
3982	}
3983
3984	Create your own board support subdirectory;
3985
3986	Create your own board config file;
3987
3988	while (!running) {
3989		do {
3990			Add / modify source code;
3991		} until (compiles);
3992		Debug;
3993		if (clueless)
3994			email ("Hi, I am having problems...");
3995	}
3996	Send patch file to Wolfgang;
3997
3998	return 0;
3999}
4000
4001void no_more_time (int sig)
4002{
4003      hire_a_guru();
4004}
4005
4006
4007Coding Standards:
4008-----------------
4009
4010All contributions to U-Boot should conform to the Linux kernel
4011coding style; see the file "Documentation/CodingStyle" and the script
4012"scripts/Lindent" in your Linux kernel source directory.  In sources
4013originating from U-Boot a style corresponding to "Lindent -pcs" (adding
4014spaces before parameters to function calls) is actually used.
4015
4016Source files originating from a different project (for example the
4017MTD subsystem) are generally exempt from these guidelines and are not
4018reformated to ease subsequent migration to newer versions of those
4019sources.
4020
4021Please note that U-Boot is implemented in C (and to some small parts in
4022Assembler); no C++ is used, so please do not use C++ style comments (//)
4023in your code.
4024
4025Please also stick to the following formatting rules:
4026- remove any trailing white space
4027- use TAB characters for indentation, not spaces
4028- make sure NOT to use DOS '\r\n' line feeds
4029- do not add more than 2 empty lines to source files
4030- do not add trailing empty lines to source files
4031
4032Submissions which do not conform to the standards may be returned
4033with a request to reformat the changes.
4034
4035
4036Submitting Patches:
4037-------------------
4038
4039Since the number of patches for U-Boot is growing, we need to
4040establish some rules. Submissions which do not conform to these rules
4041may be rejected, even when they contain important and valuable stuff.
4042
4043Please see http://www.denx.de/wiki/U-Boot/Patches for details.
4044
4045Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
4046see http://lists.denx.de/mailman/listinfo/u-boot
4047
4048When you send a patch, please include the following information with
4049it:
4050
4051* For bug fixes: a description of the bug and how your patch fixes
4052  this bug. Please try to include a way of demonstrating that the
4053  patch actually fixes something.
4054
4055* For new features: a description of the feature and your
4056  implementation.
4057
4058* A CHANGELOG entry as plaintext (separate from the patch)
4059
4060* For major contributions, your entry to the CREDITS file
4061
4062* When you add support for a new board, don't forget to add this
4063  board to the MAKEALL script, too.
4064
4065* If your patch adds new configuration options, don't forget to
4066  document these in the README file.
4067
4068* The patch itself. If you are using git (which is *strongly*
4069  recommended) you can easily generate the patch using the
4070  "git-format-patch". If you then use "git-send-email" to send it to
4071  the U-Boot mailing list, you will avoid most of the common problems
4072  with some other mail clients.
4073
4074  If you cannot use git, use "diff -purN OLD NEW". If your version of
4075  diff does not support these options, then get the latest version of
4076  GNU diff.
4077
4078  The current directory when running this command shall be the parent
4079  directory of the U-Boot source tree (i. e. please make sure that
4080  your patch includes sufficient directory information for the
4081  affected files).
4082
4083  We prefer patches as plain text. MIME attachments are discouraged,
4084  and compressed attachments must not be used.
4085
4086* If one logical set of modifications affects or creates several
4087  files, all these changes shall be submitted in a SINGLE patch file.
4088
4089* Changesets that contain different, unrelated modifications shall be
4090  submitted as SEPARATE patches, one patch per changeset.
4091
4092
4093Notes:
4094
4095* Before sending the patch, run the MAKEALL script on your patched
4096  source tree and make sure that no errors or warnings are reported
4097  for any of the boards.
4098
4099* Keep your modifications to the necessary minimum: A patch
4100  containing several unrelated changes or arbitrary reformats will be
4101  returned with a request to re-formatting / split it.
4102
4103* If you modify existing code, make sure that your new code does not
4104  add to the memory footprint of the code ;-) Small is beautiful!
4105  When adding new features, these should compile conditionally only
4106  (using #ifdef), and the resulting code with the new feature
4107  disabled must not need more memory than the old code without your
4108  modification.
4109
4110* Remember that there is a size limit of 100 kB per message on the
4111  u-boot mailing list. Bigger patches will be moderated. If they are
4112  reasonable and not too big, they will be acknowledged. But patches
4113  bigger than the size limit should be avoided.
4114