xref: /rk3399_rockchip-uboot/README (revision 83dc830b1693252d996bda920cd5f3161d7c64a9)
1#
2# (C) Copyright 2000 - 2005
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.
55
56
57Where to get help:
58==================
59
60In case you have questions about, problems with or contributions for
61U-Boot you should send a message to the U-Boot mailing list at
62<u-boot-users@lists.sourceforge.net>. There is also an archive of
63previous traffic on the mailing list - please search the archive
64before asking FAQ's. Please see
65http://lists.sourceforge.net/lists/listinfo/u-boot-users/
66
67
68Where we come from:
69===================
70
71- start from 8xxrom sources
72- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
73- clean up code
74- make it easier to add custom boards
75- make it possible to add other [PowerPC] CPUs
76- extend functions, especially:
77  * Provide extended interface to Linux boot loader
78  * S-Record download
79  * network boot
80  * PCMCIA / CompactFLash / ATA disk / SCSI ... boot
81- create ARMBoot project (http://sourceforge.net/projects/armboot)
82- add other CPU families (starting with ARM)
83- create U-Boot project (http://sourceforge.net/projects/u-boot)
84
85
86Names and Spelling:
87===================
88
89The "official" name of this project is "Das U-Boot". The spelling
90"U-Boot" shall be used in all written text (documentation, comments
91in source files etc.). Example:
92
93	This is the README file for the U-Boot project.
94
95File names etc. shall be based on the string "u-boot". Examples:
96
97	include/asm-ppc/u-boot.h
98
99	#include <asm/u-boot.h>
100
101Variable names, preprocessor constants etc. shall be either based on
102the string "u_boot" or on "U_BOOT". Example:
103
104	U_BOOT_VERSION		u_boot_logo
105	IH_OS_U_BOOT		u_boot_hush_start
106
107
108Versioning:
109===========
110
111U-Boot uses a 3 level version number containing a version, a
112sub-version, and a patchlevel: "U-Boot-2.34.5" means version "2",
113sub-version "34", and patchlevel "4".
114
115The patchlevel is used to indicate certain stages of development
116between released versions, i. e. officially released versions of
117U-Boot will always have a patchlevel of "0".
118
119
120Directory Hierarchy:
121====================
122
123- board		Board dependent files
124- common	Misc architecture independent functions
125- cpu		CPU specific files
126  - 74xx_7xx	Files specific to Freescale MPC74xx and 7xx CPUs
127  - arm720t	Files specific to ARM 720 CPUs
128  - arm920t	Files specific to ARM 920 CPUs
129    - at91rm9200 Files specific to Atmel AT91RM9200 CPU
130    - imx	Files specific to Freescale MC9328 i.MX CPUs
131    - s3c24x0	Files specific to Samsung S3C24X0 CPUs
132  - arm925t	Files specific to ARM 925 CPUs
133  - arm926ejs	Files specific to ARM 926 CPUs
134  - arm1136	Files specific to ARM 1136 CPUs
135  - at32ap	Files specific to Atmel AVR32 AP CPUs
136  - i386	Files specific to i386 CPUs
137  - ixp		Files specific to Intel XScale IXP CPUs
138  - mcf52x2	Files specific to Freescale ColdFire MCF52x2 CPUs
139  - mips	Files specific to MIPS CPUs
140  - mpc5xx	Files specific to Freescale MPC5xx  CPUs
141  - mpc5xxx	Files specific to Freescale MPC5xxx CPUs
142  - mpc8xx	Files specific to Freescale MPC8xx  CPUs
143  - mpc8220	Files specific to Freescale MPC8220 CPUs
144  - mpc824x	Files specific to Freescale MPC824x CPUs
145  - mpc8260	Files specific to Freescale MPC8260 CPUs
146  - mpc85xx	Files specific to Freescale MPC85xx CPUs
147  - nios	Files specific to Altera NIOS CPUs
148  - nios2	Files specific to Altera Nios-II CPUs
149  - ppc4xx	Files specific to AMCC PowerPC 4xx CPUs
150  - pxa		Files specific to Intel XScale PXA CPUs
151  - s3c44b0	Files specific to Samsung S3C44B0 CPUs
152  - sa1100	Files specific to Intel StrongARM SA1100 CPUs
153- disk		Code for disk drive partition handling
154- doc		Documentation (don't expect too much)
155- drivers	Commonly used device drivers
156- dtt		Digital Thermometer and Thermostat drivers
157- examples	Example code for standalone applications, etc.
158- include	Header Files
159- lib_arm	Files generic to ARM	 architecture
160- lib_avr32	Files generic to AVR32	 architecture
161- lib_generic	Files generic to all	 architectures
162- lib_i386	Files generic to i386	 architecture
163- lib_m68k	Files generic to m68k	 architecture
164- lib_mips	Files generic to MIPS	 architecture
165- lib_nios	Files generic to NIOS	 architecture
166- lib_ppc	Files generic to PowerPC architecture
167- net		Networking code
168- post		Power On Self Test
169- rtc		Real Time Clock drivers
170- tools		Tools to build S-Record or U-Boot images, etc.
171
172Software Configuration:
173=======================
174
175Configuration is usually done using C preprocessor defines; the
176rationale behind that is to avoid dead code whenever possible.
177
178There are two classes of configuration variables:
179
180* Configuration _OPTIONS_:
181  These are selectable by the user and have names beginning with
182  "CONFIG_".
183
184* Configuration _SETTINGS_:
185  These depend on the hardware etc. and should not be meddled with if
186  you don't know what you're doing; they have names beginning with
187  "CFG_".
188
189Later we will add a configuration tool - probably similar to or even
190identical to what's used for the Linux kernel. Right now, we have to
191do the configuration by hand, which means creating some symbolic
192links and editing some configuration files. We use the TQM8xxL boards
193as an example here.
194
195
196Selection of Processor Architecture and Board Type:
197---------------------------------------------------
198
199For all supported boards there are ready-to-use default
200configurations available; just type "make <board_name>_config".
201
202Example: For a TQM823L module type:
203
204	cd u-boot
205	make TQM823L_config
206
207For the Cogent platform, you need to specify the cpu type as well;
208e.g. "make cogent_mpc8xx_config". And also configure the cogent
209directory according to the instructions in cogent/README.
210
211
212Configuration Options:
213----------------------
214
215Configuration depends on the combination of board and CPU type; all
216such information is kept in a configuration file
217"include/configs/<board_name>.h".
218
219Example: For a TQM823L module, all configuration settings are in
220"include/configs/TQM823L.h".
221
222
223Many of the options are named exactly as the corresponding Linux
224kernel configuration options. The intention is to make it easier to
225build a config tool - later.
226
227
228The following options need to be configured:
229
230- CPU Type:	Define exactly one of
231
232		PowerPC based CPUs:
233		-------------------
234		CONFIG_MPC823,	CONFIG_MPC850,	CONFIG_MPC855,	CONFIG_MPC860
235	or	CONFIG_MPC5xx
236	or	CONFIG_MPC8220
237	or	CONFIG_MPC824X, CONFIG_MPC8260
238	or	CONFIG_MPC85xx
239	or	CONFIG_IOP480
240	or	CONFIG_405GP
241	or	CONFIG_405EP
242	or	CONFIG_440
243	or	CONFIG_MPC74xx
244	or	CONFIG_750FX
245
246		ARM based CPUs:
247		---------------
248		CONFIG_SA1110
249		CONFIG_ARM7
250		CONFIG_PXA250
251		CONFIG_CPU_MONAHANS
252
253		MicroBlaze based CPUs:
254		----------------------
255		CONFIG_MICROBLAZE
256
257		Nios-2 based CPUs:
258		----------------------
259		CONFIG_NIOS2
260
261		AVR32 based CPUs:
262		----------------------
263		CONFIG_AT32AP
264
265- Board Type:	Define exactly one of
266
267		PowerPC based boards:
268		---------------------
269
270		CONFIG_ADCIOP		CONFIG_FPS860L		CONFIG_OXC
271		CONFIG_ADS860		CONFIG_GEN860T		CONFIG_PCI405
272		CONFIG_AMX860		CONFIG_GENIETV		CONFIG_PCIPPC2
273		CONFIG_AP1000		CONFIG_GTH		CONFIG_PCIPPC6
274		CONFIG_AR405		CONFIG_gw8260		CONFIG_pcu_e
275		CONFIG_BAB7xx		CONFIG_hermes		CONFIG_PIP405
276		CONFIG_BC3450		CONFIG_hymod		CONFIG_PM826
277		CONFIG_c2mon		CONFIG_IAD210		CONFIG_ppmc8260
278		CONFIG_CANBT		CONFIG_ICU862		CONFIG_QS823
279		CONFIG_CCM		CONFIG_IP860		CONFIG_QS850
280		CONFIG_CMI		CONFIG_IPHASE4539	CONFIG_QS860T
281		CONFIG_cogent_mpc8260	CONFIG_IVML24		CONFIG_RBC823
282		CONFIG_cogent_mpc8xx	CONFIG_IVML24_128	CONFIG_RPXClassic
283		CONFIG_CPCI405		CONFIG_IVML24_256	CONFIG_RPXlite
284		CONFIG_CPCI4052		CONFIG_IVMS8		CONFIG_RPXsuper
285		CONFIG_CPCIISER4	CONFIG_IVMS8_128	CONFIG_rsdproto
286		CONFIG_CPU86		CONFIG_IVMS8_256	CONFIG_sacsng
287		CONFIG_CRAYL1		CONFIG_JSE		CONFIG_Sandpoint8240
288		CONFIG_CSB272		CONFIG_LANTEC		CONFIG_Sandpoint8245
289		CONFIG_CU824		CONFIG_LITE5200B	CONFIG_sbc8260
290		CONFIG_DASA_SIM		CONFIG_lwmon		CONFIG_sbc8560
291		CONFIG_DB64360		CONFIG_MBX		CONFIG_SM850
292		CONFIG_DB64460		CONFIG_MBX860T		CONFIG_SPD823TS
293		CONFIG_DU405		CONFIG_MHPC		CONFIG_STXGP3
294		CONFIG_DUET_ADS		CONFIG_MIP405		CONFIG_SXNI855T
295		CONFIG_EBONY		CONFIG_MOUSSE		CONFIG_TQM823L
296		CONFIG_ELPPC		CONFIG_MPC8260ADS	CONFIG_TQM8260
297		CONFIG_ELPT860		CONFIG_MPC8540ADS	CONFIG_TQM850L
298		CONFIG_ep8260		CONFIG_MPC8540EVAL	CONFIG_TQM855L
299		CONFIG_ERIC		CONFIG_MPC8560ADS	CONFIG_TQM860L
300		CONFIG_ESTEEM192E	CONFIG_MUSENKI		CONFIG_TTTech
301		CONFIG_ETX094		CONFIG_MVS1		CONFIG_UTX8245
302		CONFIG_EVB64260		CONFIG_NETPHONE		CONFIG_V37
303		CONFIG_FADS823		CONFIG_NETTA		CONFIG_W7OLMC
304		CONFIG_FADS850SAR	CONFIG_NETVIA		CONFIG_W7OLMG
305		CONFIG_FADS860T		CONFIG_NX823		CONFIG_WALNUT
306		CONFIG_FLAGADM		CONFIG_OCRTC		CONFIG_ZPC1900
307		CONFIG_FPS850L		CONFIG_ORSG		CONFIG_ZUMA
308
309		ARM based boards:
310		-----------------
311
312		CONFIG_ARMADILLO,	CONFIG_AT91RM9200DK,	CONFIG_CERF250,
313		CONFIG_CSB637,		CONFIG_DELTA,		CONFIG_DNP1110,
314		CONFIG_EP7312,		CONFIG_H2_OMAP1610,	CONFIG_HHP_CRADLE,
315		CONFIG_IMPA7,	    CONFIG_INNOVATOROMAP1510,	CONFIG_INNOVATOROMAP1610,
316		CONFIG_KB9202,		CONFIG_LART,		CONFIG_LPD7A400,
317		CONFIG_LUBBOCK,		CONFIG_OSK_OMAP5912,	CONFIG_OMAP2420H4,
318		CONFIG_PLEB2,		CONFIG_SHANNON,		CONFIG_P2_OMAP730,
319		CONFIG_SMDK2400,	CONFIG_SMDK2410,	CONFIG_TRAB,
320		CONFIG_VCMA9
321
322		MicroBlaze based boards:
323		------------------------
324
325		CONFIG_SUZAKU
326
327		Nios-2 based boards:
328		------------------------
329
330		CONFIG_PCI5441 CONFIG_PK1C20
331		CONFIG_EP1C20 CONFIG_EP1S10 CONFIG_EP1S40
332
333		AVR32 based boards:
334		-------------------
335
336		CONFIG_ATSTK1000
337
338- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
339		Define exactly one of
340		CONFIG_ATSTK1002
341
342
343- CPU Module Type: (if CONFIG_COGENT is defined)
344		Define exactly one of
345		CONFIG_CMA286_60_OLD
346--- FIXME --- not tested yet:
347		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
348		CONFIG_CMA287_23, CONFIG_CMA287_50
349
350- Motherboard Type: (if CONFIG_COGENT is defined)
351		Define exactly one of
352		CONFIG_CMA101, CONFIG_CMA102
353
354- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
355		Define one or more of
356		CONFIG_CMA302
357
358- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
359		Define one or more of
360		CONFIG_LCD_HEARTBEAT	- update a character position on
361					  the lcd display every second with
362					  a "rotator" |\-/|\-/
363
364- Board flavour: (if CONFIG_MPC8260ADS is defined)
365		CONFIG_ADSTYPE
366		Possible values are:
367			CFG_8260ADS	- original MPC8260ADS
368			CFG_8266ADS	- MPC8266ADS
369			CFG_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
370			CFG_8272ADS	- MPC8272ADS
371
372- MPC824X Family Member (if CONFIG_MPC824X is defined)
373		Define exactly one of
374		CONFIG_MPC8240, CONFIG_MPC8245
375
376- 8xx CPU Options: (if using an MPC8xx cpu)
377		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
378					  get_gclk_freq() cannot work
379					  e.g. if there is no 32KHz
380					  reference PIT/RTC clock
381		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
382					  or XTAL/EXTAL)
383
384- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
385		CFG_8xx_CPUCLK_MIN
386		CFG_8xx_CPUCLK_MAX
387		CONFIG_8xx_CPUCLK_DEFAULT
388			See doc/README.MPC866
389
390		CFG_MEASURE_CPUCLK
391
392		Define this to measure the actual CPU clock instead
393		of relying on the correctness of the configured
394		values. Mostly useful for board bringup to make sure
395		the PLL is locked at the intended frequency. Note
396		that this requires a (stable) reference clock (32 kHz
397		RTC clock or CFG_8XX_XIN)
398
399- Intel Monahans options:
400		CFG_MONAHANS_RUN_MODE_OSC_RATIO
401
402		Defines the Monahans run mode to oscillator
403		ratio. Valid values are 8, 16, 24, 31. The core
404		frequency is this value multiplied by 13 MHz.
405
406		CFG_MONAHANS_TURBO_RUN_MODE_RATIO
407
408		Defines the Monahans turbo mode to oscillator
409		ratio. Valid values are 1 (default if undefined) and
410		2. The core frequency as calculated above is multiplied
411		by this value.
412
413- Linux Kernel Interface:
414		CONFIG_CLOCKS_IN_MHZ
415
416		U-Boot stores all clock information in Hz
417		internally. For binary compatibility with older Linux
418		kernels (which expect the clocks passed in the
419		bd_info data to be in MHz) the environment variable
420		"clocks_in_mhz" can be defined so that U-Boot
421		converts clock data to MHZ before passing it to the
422		Linux kernel.
423		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
424		"clocks_in_mhz=1" is  automatically  included  in  the
425		default environment.
426
427		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
428
429		When transfering memsize parameter to linux, some versions
430		expect it to be in bytes, others in MB.
431		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
432
433		CONFIG_OF_FLAT_TREE
434
435		New kernel versions are expecting firmware settings to be
436		passed using flat open firmware trees.
437		The environment variable "disable_of", when set, disables this
438		functionality.
439
440		CONFIG_OF_FLAT_TREE_MAX_SIZE
441
442		The maximum size of the constructed OF tree.
443
444		OF_CPU - The proper name of the cpus node.
445		OF_SOC - The proper name of the soc node.
446		OF_TBCLK - The timebase frequency.
447		OF_STDOUT_PATH - The path to the console device
448
449		CONFIG_OF_HAS_BD_T
450
451		The resulting flat device tree will have a copy of the bd_t.
452		Space should be pre-allocated in the dts for the bd_t.
453
454		CONFIG_OF_HAS_UBOOT_ENV
455
456		The resulting flat device tree will have a copy of u-boot's
457		environment variables
458
459		CONFIG_OF_BOARD_SETUP
460
461		Board code has addition modification that it wants to make
462		to the flat device tree before handing it off to the kernel
463
464		CONFIG_OF_BOOT_CPU
465
466		This define fills in the correct boot cpu in the boot
467		param header, the default value is zero if undefined.
468
469- Serial Ports:
470		CFG_PL010_SERIAL
471
472		Define this if you want support for Amba PrimeCell PL010 UARTs.
473
474		CFG_PL011_SERIAL
475
476		Define this if you want support for Amba PrimeCell PL011 UARTs.
477
478		CONFIG_PL011_CLOCK
479
480		If you have Amba PrimeCell PL011 UARTs, set this variable to
481		the clock speed of the UARTs.
482
483		CONFIG_PL01x_PORTS
484
485		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
486		define this to a list of base addresses for each (supported)
487		port. See e.g. include/configs/versatile.h
488
489
490- Console Interface:
491		Depending on board, define exactly one serial port
492		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
493		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
494		console by defining CONFIG_8xx_CONS_NONE
495
496		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
497		port routines must be defined elsewhere
498		(i.e. serial_init(), serial_getc(), ...)
499
500		CONFIG_CFB_CONSOLE
501		Enables console device for a color framebuffer. Needs following
502		defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
503			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
504						(default big endian)
505			VIDEO_HW_RECTFILL	graphic chip supports
506						rectangle fill
507						(cf. smiLynxEM)
508			VIDEO_HW_BITBLT		graphic chip supports
509						bit-blit (cf. smiLynxEM)
510			VIDEO_VISIBLE_COLS	visible pixel columns
511						(cols=pitch)
512			VIDEO_VISIBLE_ROWS	visible pixel rows
513			VIDEO_PIXEL_SIZE	bytes per pixel
514			VIDEO_DATA_FORMAT	graphic data format
515						(0-5, cf. cfb_console.c)
516			VIDEO_FB_ADRS		framebuffer address
517			VIDEO_KBD_INIT_FCT	keyboard int fct
518						(i.e. i8042_kbd_init())
519			VIDEO_TSTC_FCT		test char fct
520						(i.e. i8042_tstc)
521			VIDEO_GETC_FCT		get char fct
522						(i.e. i8042_getc)
523			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
524						(requires blink timer
525						cf. i8042.c)
526			CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
527			CONFIG_CONSOLE_TIME	display time/date info in
528						upper right corner
529						(requires CFG_CMD_DATE)
530			CONFIG_VIDEO_LOGO	display Linux logo in
531						upper left corner
532			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
533						linux_logo.h for logo.
534						Requires CONFIG_VIDEO_LOGO
535			CONFIG_CONSOLE_EXTRA_INFO
536						addional board info beside
537						the logo
538
539		When CONFIG_CFB_CONSOLE is defined, video console is
540		default i/o. Serial console can be forced with
541		environment 'console=serial'.
542
543		When CONFIG_SILENT_CONSOLE is defined, all console
544		messages (by U-Boot and Linux!) can be silenced with
545		the "silent" environment variable. See
546		doc/README.silent for more information.
547
548- Console Baudrate:
549		CONFIG_BAUDRATE - in bps
550		Select one of the baudrates listed in
551		CFG_BAUDRATE_TABLE, see below.
552		CFG_BRGCLK_PRESCALE, baudrate prescale
553
554- Interrupt driven serial port input:
555		CONFIG_SERIAL_SOFTWARE_FIFO
556
557		PPC405GP only.
558		Use an interrupt handler for receiving data on the
559		serial port. It also enables using hardware handshake
560		(RTS/CTS) and UART's built-in FIFO. Set the number of
561		bytes the interrupt driven input buffer should have.
562
563		Leave undefined to disable this feature, including
564		disable the buffer and hardware handshake.
565
566- Console UART Number:
567		CONFIG_UART1_CONSOLE
568
569		AMCC PPC4xx only.
570		If defined internal UART1 (and not UART0) is used
571		as default U-Boot console.
572
573- Boot Delay:	CONFIG_BOOTDELAY - in seconds
574		Delay before automatically booting the default image;
575		set to -1 to disable autoboot.
576
577		See doc/README.autoboot for these options that
578		work with CONFIG_BOOTDELAY. None are required.
579		CONFIG_BOOT_RETRY_TIME
580		CONFIG_BOOT_RETRY_MIN
581		CONFIG_AUTOBOOT_KEYED
582		CONFIG_AUTOBOOT_PROMPT
583		CONFIG_AUTOBOOT_DELAY_STR
584		CONFIG_AUTOBOOT_STOP_STR
585		CONFIG_AUTOBOOT_DELAY_STR2
586		CONFIG_AUTOBOOT_STOP_STR2
587		CONFIG_ZERO_BOOTDELAY_CHECK
588		CONFIG_RESET_TO_RETRY
589
590- Autoboot Command:
591		CONFIG_BOOTCOMMAND
592		Only needed when CONFIG_BOOTDELAY is enabled;
593		define a command string that is automatically executed
594		when no character is read on the console interface
595		within "Boot Delay" after reset.
596
597		CONFIG_BOOTARGS
598		This can be used to pass arguments to the bootm
599		command. The value of CONFIG_BOOTARGS goes into the
600		environment value "bootargs".
601
602		CONFIG_RAMBOOT and CONFIG_NFSBOOT
603		The value of these goes into the environment as
604		"ramboot" and "nfsboot" respectively, and can be used
605		as a convenience, when switching between booting from
606		ram and nfs.
607
608- Pre-Boot Commands:
609		CONFIG_PREBOOT
610
611		When this option is #defined, the existence of the
612		environment variable "preboot" will be checked
613		immediately before starting the CONFIG_BOOTDELAY
614		countdown and/or running the auto-boot command resp.
615		entering interactive mode.
616
617		This feature is especially useful when "preboot" is
618		automatically generated or modified. For an example
619		see the LWMON board specific code: here "preboot" is
620		modified when the user holds down a certain
621		combination of keys on the (special) keyboard when
622		booting the systems
623
624- Serial Download Echo Mode:
625		CONFIG_LOADS_ECHO
626		If defined to 1, all characters received during a
627		serial download (using the "loads" command) are
628		echoed back. This might be needed by some terminal
629		emulations (like "cu"), but may as well just take
630		time on others. This setting #define's the initial
631		value of the "loads_echo" environment variable.
632
633- Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined)
634		CONFIG_KGDB_BAUDRATE
635		Select one of the baudrates listed in
636		CFG_BAUDRATE_TABLE, see below.
637
638- Monitor Functions:
639		CONFIG_COMMANDS
640		Most monitor functions can be selected (or
641		de-selected) by adjusting the definition of
642		CONFIG_COMMANDS; to select individual functions,
643		#define CONFIG_COMMANDS by "OR"ing any of the
644		following values:
645
646		#define enables commands:
647		-------------------------
648		CFG_CMD_ASKENV	* ask for env variable
649		CFG_CMD_AUTOSCRIPT Autoscript Support
650		CFG_CMD_BDI	  bdinfo
651		CFG_CMD_BEDBUG	* Include BedBug Debugger
652		CFG_CMD_BMP	* BMP support
653		CFG_CMD_BSP	* Board specific commands
654		CFG_CMD_BOOTD	  bootd
655		CFG_CMD_CACHE	* icache, dcache
656		CFG_CMD_CONSOLE	  coninfo
657		CFG_CMD_DATE	* support for RTC, date/time...
658		CFG_CMD_DHCP	* DHCP support
659		CFG_CMD_DIAG	* Diagnostics
660		CFG_CMD_DOC	* Disk-On-Chip Support
661		CFG_CMD_DTT	* Digital Therm and Thermostat
662		CFG_CMD_ECHO	  echo arguments
663		CFG_CMD_EEPROM	* EEPROM read/write support
664		CFG_CMD_ELF	* bootelf, bootvx
665		CFG_CMD_ENV	  saveenv
666		CFG_CMD_FDC	* Floppy Disk Support
667		CFG_CMD_FAT	* FAT partition support
668		CFG_CMD_FDOS	* Dos diskette Support
669		CFG_CMD_FLASH	  flinfo, erase, protect
670		CFG_CMD_FPGA	  FPGA device initialization support
671		CFG_CMD_HWFLOW	* RTS/CTS hw flow control
672		CFG_CMD_I2C	* I2C serial bus support
673		CFG_CMD_IDE	* IDE harddisk support
674		CFG_CMD_IMI	  iminfo
675		CFG_CMD_IMLS	  List all found images
676		CFG_CMD_IMMAP	* IMMR dump support
677		CFG_CMD_IRQ	* irqinfo
678		CFG_CMD_ITEST	  Integer/string test of 2 values
679		CFG_CMD_JFFS2	* JFFS2 Support
680		CFG_CMD_KGDB	* kgdb
681		CFG_CMD_LOADB	  loadb
682		CFG_CMD_LOADS	  loads
683		CFG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
684				  loop, loopw, mtest
685		CFG_CMD_MISC	  Misc functions like sleep etc
686		CFG_CMD_MMC	* MMC memory mapped support
687		CFG_CMD_MII	* MII utility commands
688		CFG_CMD_NAND	* NAND support
689		CFG_CMD_NET	  bootp, tftpboot, rarpboot
690		CFG_CMD_PCI	* pciinfo
691		CFG_CMD_PCMCIA	* PCMCIA support
692		CFG_CMD_PING	* send ICMP ECHO_REQUEST to network host
693		CFG_CMD_PORTIO	* Port I/O
694		CFG_CMD_REGINFO * Register dump
695		CFG_CMD_RUN	  run command in env variable
696		CFG_CMD_SAVES	* save S record dump
697		CFG_CMD_SCSI	* SCSI Support
698		CFG_CMD_SDRAM	* print SDRAM configuration information
699				  (requires CFG_CMD_I2C)
700		CFG_CMD_SETGETDCR Support for DCR Register access (4xx only)
701		CFG_CMD_SPI	* SPI serial bus support
702		CFG_CMD_USB	* USB support
703		CFG_CMD_VFD	* VFD support (TRAB)
704		CFG_CMD_BSP	* Board SPecific functions
705		CFG_CMD_CDP	* Cisco Discover Protocol support
706		-----------------------------------------------
707		CFG_CMD_ALL	all
708
709		CONFIG_CMD_DFL	Default configuration; at the moment
710				this is includes all commands, except
711				the ones marked with "*" in the list
712				above.
713
714		If you don't define CONFIG_COMMANDS it defaults to
715		CONFIG_CMD_DFL in include/cmd_confdefs.h. A board can
716		override the default settings in the respective
717		include file.
718
719		EXAMPLE: If you want all functions except of network
720		support you can write:
721
722		#define CONFIG_COMMANDS (CFG_CMD_ALL & ~CFG_CMD_NET)
723
724
725	Note:	Don't enable the "icache" and "dcache" commands
726		(configuration option CFG_CMD_CACHE) unless you know
727		what you (and your U-Boot users) are doing. Data
728		cache cannot be enabled on systems like the 8xx or
729		8260 (where accesses to the IMMR region must be
730		uncached), and it cannot be disabled on all other
731		systems where we (mis-) use the data cache to hold an
732		initial stack and some data.
733
734
735		XXX - this list needs to get updated!
736
737- Watchdog:
738		CONFIG_WATCHDOG
739		If this variable is defined, it enables watchdog
740		support. There must be support in the platform specific
741		code for a watchdog. For the 8xx and 8260 CPUs, the
742		SIU Watchdog feature is enabled in the SYPCR
743		register.
744
745- U-Boot Version:
746		CONFIG_VERSION_VARIABLE
747		If this variable is defined, an environment variable
748		named "ver" is created by U-Boot showing the U-Boot
749		version as printed by the "version" command.
750		This variable is readonly.
751
752- Real-Time Clock:
753
754		When CFG_CMD_DATE is selected, the type of the RTC
755		has to be selected, too. Define exactly one of the
756		following options:
757
758		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
759		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
760		CONFIG_RTC_MC146818	- use MC146818 RTC
761		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
762		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
763		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
764		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
765		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
766
767		Note that if the RTC uses I2C, then the I2C interface
768		must also be configured. See I2C Support, below.
769
770- Timestamp Support:
771
772		When CONFIG_TIMESTAMP is selected, the timestamp
773		(date and time) of an image is printed by image
774		commands like bootm or iminfo. This option is
775		automatically enabled when you select CFG_CMD_DATE .
776
777- Partition Support:
778		CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
779		and/or CONFIG_ISO_PARTITION
780
781		If IDE or SCSI support	is  enabled  (CFG_CMD_IDE  or
782		CFG_CMD_SCSI) you must configure support for at least
783		one partition type as well.
784
785- IDE Reset method:
786		CONFIG_IDE_RESET_ROUTINE - this is defined in several
787		board configurations files but used nowhere!
788
789		CONFIG_IDE_RESET - is this is defined, IDE Reset will
790		be performed by calling the function
791			ide_set_reset(int reset)
792		which has to be defined in a board specific file
793
794- ATAPI Support:
795		CONFIG_ATAPI
796
797		Set this to enable ATAPI support.
798
799- LBA48 Support
800		CONFIG_LBA48
801
802		Set this to enable support for disks larger than 137GB
803		Also look at CFG_64BIT_LBA ,CFG_64BIT_VSPRINTF and CFG_64BIT_STRTOUL
804		Whithout these , LBA48 support uses 32bit variables and will 'only'
805		support disks up to 2.1TB.
806
807		CFG_64BIT_LBA:
808			When enabled, makes the IDE subsystem use 64bit sector addresses.
809			Default is 32bit.
810
811- SCSI Support:
812		At the moment only there is only support for the
813		SYM53C8XX SCSI controller; define
814		CONFIG_SCSI_SYM53C8XX to enable it.
815
816		CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
817		CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
818		CFG_SCSI_MAX_LUN] can be adjusted to define the
819		maximum numbers of LUNs, SCSI ID's and target
820		devices.
821		CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
822
823- NETWORK Support (PCI):
824		CONFIG_E1000
825		Support for Intel 8254x gigabit chips.
826
827		CONFIG_EEPRO100
828		Support for Intel 82557/82559/82559ER chips.
829		Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom
830		write routine for first time initialisation.
831
832		CONFIG_TULIP
833		Support for Digital 2114x chips.
834		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
835		modem chip initialisation (KS8761/QS6611).
836
837		CONFIG_NATSEMI
838		Support for National dp83815 chips.
839
840		CONFIG_NS8382X
841		Support for National dp8382[01] gigabit chips.
842
843- NETWORK Support (other):
844
845		CONFIG_DRIVER_LAN91C96
846		Support for SMSC's LAN91C96 chips.
847
848			CONFIG_LAN91C96_BASE
849			Define this to hold the physical address
850			of the LAN91C96's I/O space
851
852			CONFIG_LAN91C96_USE_32_BIT
853			Define this to enable 32 bit addressing
854
855		CONFIG_DRIVER_SMC91111
856		Support for SMSC's LAN91C111 chip
857
858			CONFIG_SMC91111_BASE
859			Define this to hold the physical address
860			of the device (I/O space)
861
862			CONFIG_SMC_USE_32_BIT
863			Define this if data bus is 32 bits
864
865			CONFIG_SMC_USE_IOFUNCS
866			Define this to use i/o functions instead of macros
867			(some hardware wont work with macros)
868
869- USB Support:
870		At the moment only the UHCI host controller is
871		supported (PIP405, MIP405, MPC5200); define
872		CONFIG_USB_UHCI to enable it.
873		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
874		and define CONFIG_USB_STORAGE to enable the USB
875		storage devices.
876		Note:
877		Supported are USB Keyboards and USB Floppy drives
878		(TEAC FD-05PUB).
879		MPC5200 USB requires additional defines:
880			CONFIG_USB_CLOCK
881				for 528 MHz Clock: 0x0001bbbb
882			CONFIG_USB_CONFIG
883				for differential drivers: 0x00001000
884				for single ended drivers: 0x00005000
885
886- USB Device:
887		Define the below if you wish to use the USB console.
888		Once firmware is rebuilt from a serial console issue the
889		command "setenv stdin usbtty; setenv stdout usbtty" and
890		attach your usb cable. The Unix command "dmesg" should print
891		it has found a new device. The environment variable usbtty
892		can be set to gserial or cdc_acm to enable your device to
893		appear to a USB host as a Linux gserial device or a
894		Common Device Class Abstract Control Model serial device.
895		If you select usbtty = gserial you should be able to enumerate
896		a Linux host by
897		# modprobe usbserial vendor=0xVendorID product=0xProductID
898		else if using cdc_acm, simply setting the environment
899		variable usbtty to be cdc_acm should suffice. The following
900		might be defined in YourBoardName.h
901
902			CONFIG_USB_DEVICE
903			Define this to build a UDC device
904
905			CONFIG_USB_TTY
906			Define this to have a tty type of device available to
907			talk to the UDC device
908
909			CFG_CONSOLE_IS_IN_ENV
910			Define this if you want stdin, stdout &/or stderr to
911			be set to usbtty.
912
913			mpc8xx:
914				CFG_USB_EXTC_CLK 0xBLAH
915				Derive USB clock from external clock "blah"
916				- CFG_USB_EXTC_CLK 0x02
917
918				CFG_USB_BRG_CLK 0xBLAH
919				Derive USB clock from brgclk
920				- CFG_USB_BRG_CLK 0x04
921
922		If you have a USB-IF assigned VendorID then you may wish to
923		define your own vendor specific values either in BoardName.h
924		or directly in usbd_vendor_info.h. If you don't define
925		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
926		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
927		should pretend to be a Linux device to it's target host.
928
929			CONFIG_USBD_MANUFACTURER
930			Define this string as the name of your company for
931			- CONFIG_USBD_MANUFACTURER "my company"
932
933			CONFIG_USBD_PRODUCT_NAME
934			Define this string as the name of your product
935			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
936
937			CONFIG_USBD_VENDORID
938			Define this as your assigned Vendor ID from the USB
939			Implementors Forum. This *must* be a genuine Vendor ID
940			to avoid polluting the USB namespace.
941			- CONFIG_USBD_VENDORID 0xFFFF
942
943			CONFIG_USBD_PRODUCTID
944			Define this as the unique Product ID
945			for your device
946			- CONFIG_USBD_PRODUCTID 0xFFFF
947
948
949- MMC Support:
950		The MMC controller on the Intel PXA is supported. To
951		enable this define CONFIG_MMC. The MMC can be
952		accessed from the boot prompt by mapping the device
953		to physical memory similar to flash. Command line is
954		enabled with CFG_CMD_MMC. The MMC driver also works with
955		the FAT fs. This is enabled with CFG_CMD_FAT.
956
957- Journaling Flash filesystem support:
958		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
959		CONFIG_JFFS2_NAND_DEV
960		Define these for a default partition on a NAND device
961
962		CFG_JFFS2_FIRST_SECTOR,
963		CFG_JFFS2_FIRST_BANK, CFG_JFFS2_NUM_BANKS
964		Define these for a default partition on a NOR device
965
966		CFG_JFFS_CUSTOM_PART
967		Define this to create an own partition. You have to provide a
968		function struct part_info* jffs2_part_info(int part_num)
969
970		If you define only one JFFS2 partition you may also want to
971		#define CFG_JFFS_SINGLE_PART	1
972		to disable the command chpart. This is the default when you
973		have not defined a custom partition
974
975- Keyboard Support:
976		CONFIG_ISA_KEYBOARD
977
978		Define this to enable standard (PC-Style) keyboard
979		support
980
981		CONFIG_I8042_KBD
982		Standard PC keyboard driver with US (is default) and
983		GERMAN key layout (switch via environment 'keymap=de') support.
984		Export function i8042_kbd_init, i8042_tstc and i8042_getc
985		for cfb_console. Supports cursor blinking.
986
987- Video support:
988		CONFIG_VIDEO
989
990		Define this to enable video support (for output to
991		video).
992
993		CONFIG_VIDEO_CT69000
994
995		Enable Chips & Technologies 69000 Video chip
996
997		CONFIG_VIDEO_SMI_LYNXEM
998		Enable Silicon Motion SMI 712/710/810 Video chip. The
999		video output is selected via environment 'videoout'
1000		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1001		assumed.
1002
1003		For the CT69000 and SMI_LYNXEM drivers, videomode is
1004		selected via environment 'videomode'. Two diferent ways
1005		are possible:
1006		- "videomode=num"   'num' is a standard LiLo mode numbers.
1007		Following standard modes are supported	(* is default):
1008
1009		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1010		-------------+---------------------------------------------
1011		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1012		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1013		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1014		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1015		-------------+---------------------------------------------
1016		(i.e. setenv videomode 317; saveenv; reset;)
1017
1018		- "videomode=bootargs" all the video parameters are parsed
1019		from the bootargs. (See drivers/videomodes.c)
1020
1021
1022		CONFIG_VIDEO_SED13806
1023		Enable Epson SED13806 driver. This driver supports 8bpp
1024		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1025		or CONFIG_VIDEO_SED13806_16BPP
1026
1027- Keyboard Support:
1028		CONFIG_KEYBOARD
1029
1030		Define this to enable a custom keyboard support.
1031		This simply calls drv_keyboard_init() which must be
1032		defined in your board-specific files.
1033		The only board using this so far is RBC823.
1034
1035- LCD Support:	CONFIG_LCD
1036
1037		Define this to enable LCD support (for output to LCD
1038		display); also select one of the supported displays
1039		by defining one of these:
1040
1041		CONFIG_NEC_NL6448AC33:
1042
1043			NEC NL6448AC33-18. Active, color, single scan.
1044
1045		CONFIG_NEC_NL6448BC20
1046
1047			NEC NL6448BC20-08. 6.5", 640x480.
1048			Active, color, single scan.
1049
1050		CONFIG_NEC_NL6448BC33_54
1051
1052			NEC NL6448BC33-54. 10.4", 640x480.
1053			Active, color, single scan.
1054
1055		CONFIG_SHARP_16x9
1056
1057			Sharp 320x240. Active, color, single scan.
1058			It isn't 16x9, and I am not sure what it is.
1059
1060		CONFIG_SHARP_LQ64D341
1061
1062			Sharp LQ64D341 display, 640x480.
1063			Active, color, single scan.
1064
1065		CONFIG_HLD1045
1066
1067			HLD1045 display, 640x480.
1068			Active, color, single scan.
1069
1070		CONFIG_OPTREX_BW
1071
1072			Optrex	 CBL50840-2 NF-FW 99 22 M5
1073			or
1074			Hitachi	 LMG6912RPFC-00T
1075			or
1076			Hitachi	 SP14Q002
1077
1078			320x240. Black & white.
1079
1080		Normally display is black on white background; define
1081		CFG_WHITE_ON_BLACK to get it inverted.
1082
1083- Splash Screen Support: CONFIG_SPLASH_SCREEN
1084
1085		If this option is set, the environment is checked for
1086		a variable "splashimage". If found, the usual display
1087		of logo, copyright and system information on the LCD
1088		is suppressed and the BMP image at the address
1089		specified in "splashimage" is loaded instead. The
1090		console is redirected to the "nulldev", too. This
1091		allows for a "silent" boot where a splash screen is
1092		loaded very quickly after power-on.
1093
1094- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1095
1096		If this option is set, additionally to standard BMP
1097		images, gzipped BMP images can be displayed via the
1098		splashscreen support or the bmp command.
1099
1100- Compression support:
1101		CONFIG_BZIP2
1102
1103		If this option is set, support for bzip2 compressed
1104		images is included. If not, only uncompressed and gzip
1105		compressed images are supported.
1106
1107		NOTE: the bzip2 algorithm requires a lot of RAM, so
1108		the malloc area (as defined by CFG_MALLOC_LEN) should
1109		be at least 4MB.
1110
1111- MII/PHY support:
1112		CONFIG_PHY_ADDR
1113
1114		The address of PHY on MII bus.
1115
1116		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1117
1118		The clock frequency of the MII bus
1119
1120		CONFIG_PHY_GIGE
1121
1122		If this option is set, support for speed/duplex
1123		detection of Gigabit PHY is included.
1124
1125		CONFIG_PHY_RESET_DELAY
1126
1127		Some PHY like Intel LXT971A need extra delay after
1128		reset before any MII register access is possible.
1129		For such PHY, set this option to the usec delay
1130		required. (minimum 300usec for LXT971A)
1131
1132		CONFIG_PHY_CMD_DELAY (ppc4xx)
1133
1134		Some PHY like Intel LXT971A need extra delay after
1135		command issued before MII status register can be read
1136
1137- Ethernet address:
1138		CONFIG_ETHADDR
1139		CONFIG_ETH2ADDR
1140		CONFIG_ETH3ADDR
1141
1142		Define a default value for ethernet address to use
1143		for the respective ethernet interface, in case this
1144		is not determined automatically.
1145
1146- IP address:
1147		CONFIG_IPADDR
1148
1149		Define a default value for the IP address to use for
1150		the default ethernet interface, in case this is not
1151		determined through e.g. bootp.
1152
1153- Server IP address:
1154		CONFIG_SERVERIP
1155
1156		Defines a default value for theIP address of a TFTP
1157		server to contact when using the "tftboot" command.
1158
1159- BOOTP Recovery Mode:
1160		CONFIG_BOOTP_RANDOM_DELAY
1161
1162		If you have many targets in a network that try to
1163		boot using BOOTP, you may want to avoid that all
1164		systems send out BOOTP requests at precisely the same
1165		moment (which would happen for instance at recovery
1166		from a power failure, when all systems will try to
1167		boot, thus flooding the BOOTP server. Defining
1168		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1169		inserted before sending out BOOTP requests. The
1170		following delays are insterted then:
1171
1172		1st BOOTP request:	delay 0 ... 1 sec
1173		2nd BOOTP request:	delay 0 ... 2 sec
1174		3rd BOOTP request:	delay 0 ... 4 sec
1175		4th and following
1176		BOOTP requests:		delay 0 ... 8 sec
1177
1178- DHCP Advanced Options:
1179		CONFIG_BOOTP_MASK
1180
1181		You can fine tune the DHCP functionality by adding
1182		these flags to the CONFIG_BOOTP_MASK define:
1183
1184		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1185		serverip from a DHCP server, it is possible that more
1186		than one DNS serverip is offered to the client.
1187		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1188		serverip will be stored in the additional environment
1189		variable "dnsip2". The first DNS serverip is always
1190		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1191		is added to the CONFIG_BOOTP_MASK.
1192
1193		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1194		to do a dynamic update of a DNS server. To do this, they
1195		need the hostname of the DHCP requester.
1196		If CONFIG_BOOP_SEND_HOSTNAME is added to the
1197		CONFIG_BOOTP_MASK, the content of the "hostname"
1198		environment variable is passed as option 12 to
1199		the DHCP server.
1200
1201 - CDP Options:
1202		CONFIG_CDP_DEVICE_ID
1203
1204		The device id used in CDP trigger frames.
1205
1206		CONFIG_CDP_DEVICE_ID_PREFIX
1207
1208		A two character string which is prefixed to the MAC address
1209		of the device.
1210
1211		CONFIG_CDP_PORT_ID
1212
1213		A printf format string which contains the ascii name of
1214		the port. Normally is set to "eth%d" which sets
1215		eth0 for the first ethernet, eth1 for the second etc.
1216
1217		CONFIG_CDP_CAPABILITIES
1218
1219		A 32bit integer which indicates the device capabilities;
1220		0x00000010 for a normal host which does not forwards.
1221
1222		CONFIG_CDP_VERSION
1223
1224		An ascii string containing the version of the software.
1225
1226		CONFIG_CDP_PLATFORM
1227
1228		An ascii string containing the name of the platform.
1229
1230		CONFIG_CDP_TRIGGER
1231
1232		A 32bit integer sent on the trigger.
1233
1234		CONFIG_CDP_POWER_CONSUMPTION
1235
1236		A 16bit integer containing the power consumption of the
1237		device in .1 of milliwatts.
1238
1239		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1240
1241		A byte containing the id of the VLAN.
1242
1243- Status LED:	CONFIG_STATUS_LED
1244
1245		Several configurations allow to display the current
1246		status using a LED. For instance, the LED will blink
1247		fast while running U-Boot code, stop blinking as
1248		soon as a reply to a BOOTP request was received, and
1249		start blinking slow once the Linux kernel is running
1250		(supported by a status LED driver in the Linux
1251		kernel). Defining CONFIG_STATUS_LED enables this
1252		feature in U-Boot.
1253
1254- CAN Support:	CONFIG_CAN_DRIVER
1255
1256		Defining CONFIG_CAN_DRIVER enables CAN driver support
1257		on those systems that support this (optional)
1258		feature, like the TQM8xxL modules.
1259
1260- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1261
1262		These enable I2C serial bus commands. Defining either of
1263		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1264		include the appropriate I2C driver for the selected cpu.
1265
1266		This will allow you to use i2c commands at the u-boot
1267		command line (as long as you set CFG_CMD_I2C in
1268		CONFIG_COMMANDS) and communicate with i2c based realtime
1269		clock chips. See common/cmd_i2c.c for a description of the
1270		command line interface.
1271
1272		CONFIG_HARD_I2C selects the CPM hardware driver for I2C.
1273
1274		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1275		bit-banging) driver instead of CPM or similar hardware
1276		support for I2C.
1277
1278		There are several other quantities that must also be
1279		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1280
1281		In both cases you will need to define CFG_I2C_SPEED
1282		to be the frequency (in Hz) at which you wish your i2c bus
1283		to run and CFG_I2C_SLAVE to be the address of this node (ie
1284		the cpu's i2c node address).
1285
1286		Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
1287		sets the cpu up as a master node and so its address should
1288		therefore be cleared to 0 (See, eg, MPC823e User's Manual
1289		p.16-473). So, set CFG_I2C_SLAVE to 0.
1290
1291		That's all that's required for CONFIG_HARD_I2C.
1292
1293		If you use the software i2c interface (CONFIG_SOFT_I2C)
1294		then the following macros need to be defined (examples are
1295		from include/configs/lwmon.h):
1296
1297		I2C_INIT
1298
1299		(Optional). Any commands necessary to enable the I2C
1300		controller or configure ports.
1301
1302		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
1303
1304		I2C_PORT
1305
1306		(Only for MPC8260 CPU). The I/O port to use (the code
1307		assumes both bits are on the same port). Valid values
1308		are 0..3 for ports A..D.
1309
1310		I2C_ACTIVE
1311
1312		The code necessary to make the I2C data line active
1313		(driven).  If the data line is open collector, this
1314		define can be null.
1315
1316		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1317
1318		I2C_TRISTATE
1319
1320		The code necessary to make the I2C data line tri-stated
1321		(inactive).  If the data line is open collector, this
1322		define can be null.
1323
1324		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1325
1326		I2C_READ
1327
1328		Code that returns TRUE if the I2C data line is high,
1329		FALSE if it is low.
1330
1331		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1332
1333		I2C_SDA(bit)
1334
1335		If <bit> is TRUE, sets the I2C data line high. If it
1336		is FALSE, it clears it (low).
1337
1338		eg: #define I2C_SDA(bit) \
1339			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1340			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
1341
1342		I2C_SCL(bit)
1343
1344		If <bit> is TRUE, sets the I2C clock line high. If it
1345		is FALSE, it clears it (low).
1346
1347		eg: #define I2C_SCL(bit) \
1348			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1349			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
1350
1351		I2C_DELAY
1352
1353		This delay is invoked four times per clock cycle so this
1354		controls the rate of data transfer.  The data rate thus
1355		is 1 / (I2C_DELAY * 4). Often defined to be something
1356		like:
1357
1358		#define I2C_DELAY  udelay(2)
1359
1360		CFG_I2C_INIT_BOARD
1361
1362		When a board is reset during an i2c bus transfer
1363		chips might think that the current transfer is still
1364		in progress. On some boards it is possible to access
1365		the i2c SCLK line directly, either by using the
1366		processor pin as a GPIO or by having a second pin
1367		connected to the bus. If this option is defined a
1368		custom i2c_init_board() routine in boards/xxx/board.c
1369		is run early in the boot sequence.
1370
1371		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1372
1373		This option enables configuration of bi_iic_fast[] flags
1374		in u-boot bd_info structure based on u-boot environment
1375		variable "i2cfast". (see also i2cfast)
1376
1377- SPI Support:	CONFIG_SPI
1378
1379		Enables SPI driver (so far only tested with
1380		SPI EEPROM, also an instance works with Crystal A/D and
1381		D/As on the SACSng board)
1382
1383		CONFIG_SPI_X
1384
1385		Enables extended (16-bit) SPI EEPROM addressing.
1386		(symmetrical to CONFIG_I2C_X)
1387
1388		CONFIG_SOFT_SPI
1389
1390		Enables a software (bit-bang) SPI driver rather than
1391		using hardware support. This is a general purpose
1392		driver that only requires three general I/O port pins
1393		(two outputs, one input) to function. If this is
1394		defined, the board configuration must define several
1395		SPI configuration items (port pins to use, etc). For
1396		an example, see include/configs/sacsng.h.
1397
1398- FPGA Support: CONFIG_FPGA_COUNT
1399
1400		Specify the number of FPGA devices to support.
1401
1402		CONFIG_FPGA
1403
1404		Used to specify the types of FPGA devices.  For example,
1405		#define CONFIG_FPGA  CFG_XILINX_VIRTEX2
1406
1407		CFG_FPGA_PROG_FEEDBACK
1408
1409		Enable printing of hash marks during FPGA configuration.
1410
1411		CFG_FPGA_CHECK_BUSY
1412
1413		Enable checks on FPGA configuration interface busy
1414		status by the configuration function. This option
1415		will require a board or device specific function to
1416		be written.
1417
1418		CONFIG_FPGA_DELAY
1419
1420		If defined, a function that provides delays in the FPGA
1421		configuration driver.
1422
1423		CFG_FPGA_CHECK_CTRLC
1424		Allow Control-C to interrupt FPGA configuration
1425
1426		CFG_FPGA_CHECK_ERROR
1427
1428		Check for configuration errors during FPGA bitfile
1429		loading. For example, abort during Virtex II
1430		configuration if the INIT_B line goes low (which
1431		indicated a CRC error).
1432
1433		CFG_FPGA_WAIT_INIT
1434
1435		Maximum time to wait for the INIT_B line to deassert
1436		after PROB_B has been deasserted during a Virtex II
1437		FPGA configuration sequence. The default time is 500
1438		mS.
1439
1440		CFG_FPGA_WAIT_BUSY
1441
1442		Maximum time to wait for BUSY to deassert during
1443		Virtex II FPGA configuration. The default is 5 mS.
1444
1445		CFG_FPGA_WAIT_CONFIG
1446
1447		Time to wait after FPGA configuration. The default is
1448		200 mS.
1449
1450- Configuration Management:
1451		CONFIG_IDENT_STRING
1452
1453		If defined, this string will be added to the U-Boot
1454		version information (U_BOOT_VERSION)
1455
1456- Vendor Parameter Protection:
1457
1458		U-Boot considers the values of the environment
1459		variables "serial#" (Board Serial Number) and
1460		"ethaddr" (Ethernet Address) to be parameters that
1461		are set once by the board vendor / manufacturer, and
1462		protects these variables from casual modification by
1463		the user. Once set, these variables are read-only,
1464		and write or delete attempts are rejected. You can
1465		change this behviour:
1466
1467		If CONFIG_ENV_OVERWRITE is #defined in your config
1468		file, the write protection for vendor parameters is
1469		completely disabled. Anybody can change or delete
1470		these parameters.
1471
1472		Alternatively, if you #define _both_ CONFIG_ETHADDR
1473		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1474		ethernet address is installed in the environment,
1475		which can be changed exactly ONCE by the user. [The
1476		serial# is unaffected by this, i. e. it remains
1477		read-only.]
1478
1479- Protected RAM:
1480		CONFIG_PRAM
1481
1482		Define this variable to enable the reservation of
1483		"protected RAM", i. e. RAM which is not overwritten
1484		by U-Boot. Define CONFIG_PRAM to hold the number of
1485		kB you want to reserve for pRAM. You can overwrite
1486		this default value by defining an environment
1487		variable "pram" to the number of kB you want to
1488		reserve. Note that the board info structure will
1489		still show the full amount of RAM. If pRAM is
1490		reserved, a new environment variable "mem" will
1491		automatically be defined to hold the amount of
1492		remaining RAM in a form that can be passed as boot
1493		argument to Linux, for instance like that:
1494
1495			setenv bootargs ... mem=\${mem}
1496			saveenv
1497
1498		This way you can tell Linux not to use this memory,
1499		either, which results in a memory region that will
1500		not be affected by reboots.
1501
1502		*WARNING* If your board configuration uses automatic
1503		detection of the RAM size, you must make sure that
1504		this memory test is non-destructive. So far, the
1505		following board configurations are known to be
1506		"pRAM-clean":
1507
1508			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1509			HERMES, IP860, RPXlite, LWMON, LANTEC,
1510			PCU_E, FLAGADM, TQM8260
1511
1512- Error Recovery:
1513		CONFIG_PANIC_HANG
1514
1515		Define this variable to stop the system in case of a
1516		fatal error, so that you have to reset it manually.
1517		This is probably NOT a good idea for an embedded
1518		system where you want to system to reboot
1519		automatically as fast as possible, but it may be
1520		useful during development since you can try to debug
1521		the conditions that lead to the situation.
1522
1523		CONFIG_NET_RETRY_COUNT
1524
1525		This variable defines the number of retries for
1526		network operations like ARP, RARP, TFTP, or BOOTP
1527		before giving up the operation. If not defined, a
1528		default value of 5 is used.
1529
1530- Command Interpreter:
1531		CONFIG_AUTO_COMPLETE
1532
1533		Enable auto completion of commands using TAB.
1534
1535		Note that this feature has NOT been implemented yet
1536		for the "hush" shell.
1537
1538
1539		CFG_HUSH_PARSER
1540
1541		Define this variable to enable the "hush" shell (from
1542		Busybox) as command line interpreter, thus enabling
1543		powerful command line syntax like
1544		if...then...else...fi conditionals or `&&' and '||'
1545		constructs ("shell scripts").
1546
1547		If undefined, you get the old, much simpler behaviour
1548		with a somewhat smaller memory footprint.
1549
1550
1551		CFG_PROMPT_HUSH_PS2
1552
1553		This defines the secondary prompt string, which is
1554		printed when the command interpreter needs more input
1555		to complete a command. Usually "> ".
1556
1557	Note:
1558
1559		In the current implementation, the local variables
1560		space and global environment variables space are
1561		separated. Local variables are those you define by
1562		simply typing `name=value'. To access a local
1563		variable later on, you have write `$name' or
1564		`${name}'; to execute the contents of a variable
1565		directly type `$name' at the command prompt.
1566
1567		Global environment variables are those you use
1568		setenv/printenv to work with. To run a command stored
1569		in such a variable, you need to use the run command,
1570		and you must not use the '$' sign to access them.
1571
1572		To store commands and special characters in a
1573		variable, please use double quotation marks
1574		surrounding the whole text of the variable, instead
1575		of the backslashes before semicolons and special
1576		symbols.
1577
1578- Commandline Editing and History:
1579		CONFIG_CMDLINE_EDITING
1580
1581		Enable editiong and History functions for interactive
1582		commandline input operations
1583
1584- Default Environment:
1585		CONFIG_EXTRA_ENV_SETTINGS
1586
1587		Define this to contain any number of null terminated
1588		strings (variable = value pairs) that will be part of
1589		the default environment compiled into the boot image.
1590
1591		For example, place something like this in your
1592		board's config file:
1593
1594		#define CONFIG_EXTRA_ENV_SETTINGS \
1595			"myvar1=value1\0" \
1596			"myvar2=value2\0"
1597
1598		Warning: This method is based on knowledge about the
1599		internal format how the environment is stored by the
1600		U-Boot code. This is NOT an official, exported
1601		interface! Although it is unlikely that this format
1602		will change soon, there is no guarantee either.
1603		You better know what you are doing here.
1604
1605		Note: overly (ab)use of the default environment is
1606		discouraged. Make sure to check other ways to preset
1607		the environment like the autoscript function or the
1608		boot command first.
1609
1610- DataFlash Support:
1611		CONFIG_HAS_DATAFLASH
1612
1613		Defining this option enables DataFlash features and
1614		allows to read/write in Dataflash via the standard
1615		commands cp, md...
1616
1617- SystemACE Support:
1618		CONFIG_SYSTEMACE
1619
1620		Adding this option adds support for Xilinx SystemACE
1621		chips attached via some sort of local bus. The address
1622		of the chip must alsh be defined in the
1623		CFG_SYSTEMACE_BASE macro. For example:
1624
1625		#define CONFIG_SYSTEMACE
1626		#define CFG_SYSTEMACE_BASE 0xf0000000
1627
1628		When SystemACE support is added, the "ace" device type
1629		becomes available to the fat commands, i.e. fatls.
1630
1631- TFTP Fixed UDP Port:
1632		CONFIG_TFTP_PORT
1633
1634		If this is defined, the environment variable tftpsrcp
1635		is used to supply the TFTP UDP source port value.
1636		If tftpsrcp isn't defined, the normal pseudo-random port
1637		number generator is used.
1638
1639		Also, the environment variable tftpdstp is used to supply
1640		the TFTP UDP destination port value.  If tftpdstp isn't
1641		defined, the normal port 69 is used.
1642
1643		The purpose for tftpsrcp is to allow a TFTP server to
1644		blindly start the TFTP transfer using the pre-configured
1645		target IP address and UDP port. This has the effect of
1646		"punching through" the (Windows XP) firewall, allowing
1647		the remainder of the TFTP transfer to proceed normally.
1648		A better solution is to properly configure the firewall,
1649		but sometimes that is not allowed.
1650
1651- Show boot progress:
1652		CONFIG_SHOW_BOOT_PROGRESS
1653
1654		Defining this option allows to add some board-
1655		specific code (calling a user-provided function
1656		"show_boot_progress(int)") that enables you to show
1657		the system's boot progress on some display (for
1658		example, some LED's) on your board. At the moment,
1659		the following checkpoints are implemented:
1660
1661  Arg	Where			When
1662    1	common/cmd_bootm.c	before attempting to boot an image
1663   -1	common/cmd_bootm.c	Image header has bad	 magic number
1664    2	common/cmd_bootm.c	Image header has correct magic number
1665   -2	common/cmd_bootm.c	Image header has bad	 checksum
1666    3	common/cmd_bootm.c	Image header has correct checksum
1667   -3	common/cmd_bootm.c	Image data   has bad	 checksum
1668    4	common/cmd_bootm.c	Image data   has correct checksum
1669   -4	common/cmd_bootm.c	Image is for unsupported architecture
1670    5	common/cmd_bootm.c	Architecture check OK
1671   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi, standalone)
1672    6	common/cmd_bootm.c	Image Type check OK
1673   -6	common/cmd_bootm.c	gunzip uncompression error
1674   -7	common/cmd_bootm.c	Unimplemented compression type
1675    7	common/cmd_bootm.c	Uncompression OK
1676   -8	common/cmd_bootm.c	Wrong Image Type (not kernel, multi, standalone)
1677    8	common/cmd_bootm.c	Image Type check OK
1678   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
1679    9	common/cmd_bootm.c	Start initial ramdisk verification
1680  -10	common/cmd_bootm.c	Ramdisk header has bad	   magic number
1681  -11	common/cmd_bootm.c	Ramdisk header has bad	   checksum
1682   10	common/cmd_bootm.c	Ramdisk header is OK
1683  -12	common/cmd_bootm.c	Ramdisk data   has bad	   checksum
1684   11	common/cmd_bootm.c	Ramdisk data   has correct checksum
1685   12	common/cmd_bootm.c	Ramdisk verification complete, start loading
1686  -13	common/cmd_bootm.c	Wrong Image Type (not PPC Linux Ramdisk)
1687   13	common/cmd_bootm.c	Start multifile image verification
1688   14	common/cmd_bootm.c	No initial ramdisk, no multifile, continue.
1689   15	common/cmd_bootm.c	All preparation done, transferring control to OS
1690
1691  -30	lib_ppc/board.c		Fatal error, hang the system
1692  -31	post/post.c		POST test failed, detected by post_output_backlog()
1693  -32	post/post.c		POST test failed, detected by post_run_single()
1694
1695   -1	common/cmd_doc.c	Bad usage of "doc" command
1696   -1	common/cmd_doc.c	No boot device
1697   -1	common/cmd_doc.c	Unknown Chip ID on boot device
1698   -1	common/cmd_doc.c	Read Error on boot device
1699   -1	common/cmd_doc.c	Image header has bad magic number
1700
1701   -1	common/cmd_ide.c	Bad usage of "ide" command
1702   -1	common/cmd_ide.c	No boot device
1703   -1	common/cmd_ide.c	Unknown boot device
1704   -1	common/cmd_ide.c	Unknown partition table
1705   -1	common/cmd_ide.c	Invalid partition type
1706   -1	common/cmd_ide.c	Read Error on boot device
1707   -1	common/cmd_ide.c	Image header has bad magic number
1708
1709   -1	common/cmd_nand.c	Bad usage of "nand" command
1710   -1	common/cmd_nand.c	No boot device
1711   -1	common/cmd_nand.c	Unknown Chip ID on boot device
1712   -1	common/cmd_nand.c	Read Error on boot device
1713   -1	common/cmd_nand.c	Image header has bad magic number
1714
1715   -1	common/env_common.c	Environment has a bad CRC, using default
1716
1717
1718Modem Support:
1719--------------
1720
1721[so far only for SMDK2400 and TRAB boards]
1722
1723- Modem support endable:
1724		CONFIG_MODEM_SUPPORT
1725
1726- RTS/CTS Flow control enable:
1727		CONFIG_HWFLOW
1728
1729- Modem debug support:
1730		CONFIG_MODEM_SUPPORT_DEBUG
1731
1732		Enables debugging stuff (char screen[1024], dbg())
1733		for modem support. Useful only with BDI2000.
1734
1735- Interrupt support (PPC):
1736
1737		There are common interrupt_init() and timer_interrupt()
1738		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1739		for cpu specific initialization. interrupt_init_cpu()
1740		should set decrementer_count to appropriate value. If
1741		cpu resets decrementer automatically after interrupt
1742		(ppc4xx) it should set decrementer_count to zero.
1743		timer_interrupt() calls timer_interrupt_cpu() for cpu
1744		specific handling. If board has watchdog / status_led
1745		/ other_activity_monitor it works automatically from
1746		general timer_interrupt().
1747
1748- General:
1749
1750		In the target system modem support is enabled when a
1751		specific key (key combination) is pressed during
1752		power-on. Otherwise U-Boot will boot normally
1753		(autoboot). The key_pressed() fuction is called from
1754		board_init(). Currently key_pressed() is a dummy
1755		function, returning 1 and thus enabling modem
1756		initialization.
1757
1758		If there are no modem init strings in the
1759		environment, U-Boot proceed to autoboot; the
1760		previous output (banner, info printfs) will be
1761		supressed, though.
1762
1763		See also: doc/README.Modem
1764
1765
1766Configuration Settings:
1767-----------------------
1768
1769- CFG_LONGHELP: Defined when you want long help messages included;
1770		undefine this when you're short of memory.
1771
1772- CFG_PROMPT:	This is what U-Boot prints on the console to
1773		prompt for user input.
1774
1775- CFG_CBSIZE:	Buffer size for input from the Console
1776
1777- CFG_PBSIZE:	Buffer size for Console output
1778
1779- CFG_MAXARGS:	max. Number of arguments accepted for monitor commands
1780
1781- CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1782		the application (usually a Linux kernel) when it is
1783		booted
1784
1785- CFG_BAUDRATE_TABLE:
1786		List of legal baudrate settings for this board.
1787
1788- CFG_CONSOLE_INFO_QUIET
1789		Suppress display of console information at boot.
1790
1791- CFG_CONSOLE_IS_IN_ENV
1792		If the board specific function
1793			extern int overwrite_console (void);
1794		returns 1, the stdin, stderr and stdout are switched to the
1795		serial port, else the settings in the environment are used.
1796
1797- CFG_CONSOLE_OVERWRITE_ROUTINE
1798		Enable the call to overwrite_console().
1799
1800- CFG_CONSOLE_ENV_OVERWRITE
1801		Enable overwrite of previous console environment settings.
1802
1803- CFG_MEMTEST_START, CFG_MEMTEST_END:
1804		Begin and End addresses of the area used by the
1805		simple memory test.
1806
1807- CFG_ALT_MEMTEST:
1808		Enable an alternate, more extensive memory test.
1809
1810- CFG_MEMTEST_SCRATCH:
1811		Scratch address used by the alternate memory test
1812		You only need to set this if address zero isn't writeable
1813
1814- CFG_TFTP_LOADADDR:
1815		Default load address for network file downloads
1816
1817- CFG_LOADS_BAUD_CHANGE:
1818		Enable temporary baudrate change while serial download
1819
1820- CFG_SDRAM_BASE:
1821		Physical start address of SDRAM. _Must_ be 0 here.
1822
1823- CFG_MBIO_BASE:
1824		Physical start address of Motherboard I/O (if using a
1825		Cogent motherboard)
1826
1827- CFG_FLASH_BASE:
1828		Physical start address of Flash memory.
1829
1830- CFG_MONITOR_BASE:
1831		Physical start address of boot monitor code (set by
1832		make config files to be same as the text base address
1833		(TEXT_BASE) used when linking) - same as
1834		CFG_FLASH_BASE when booting from flash.
1835
1836- CFG_MONITOR_LEN:
1837		Size of memory reserved for monitor code, used to
1838		determine _at_compile_time_ (!) if the environment is
1839		embedded within the U-Boot image, or in a separate
1840		flash sector.
1841
1842- CFG_MALLOC_LEN:
1843		Size of DRAM reserved for malloc() use.
1844
1845- CFG_BOOTM_LEN:
1846		Normally compressed uImages are limited to an
1847		uncompressed size of 8 MBytes. If this is not enough,
1848		you can define CFG_BOOTM_LEN in your board config file
1849		to adjust this setting to your needs.
1850
1851- CFG_BOOTMAPSZ:
1852		Maximum size of memory mapped by the startup code of
1853		the Linux kernel; all data that must be processed by
1854		the Linux kernel (bd_info, boot arguments, eventually
1855		initrd image) must be put below this limit.
1856
1857- CFG_MAX_FLASH_BANKS:
1858		Max number of Flash memory banks
1859
1860- CFG_MAX_FLASH_SECT:
1861		Max number of sectors on a Flash chip
1862
1863- CFG_FLASH_ERASE_TOUT:
1864		Timeout for Flash erase operations (in ms)
1865
1866- CFG_FLASH_WRITE_TOUT:
1867		Timeout for Flash write operations (in ms)
1868
1869- CFG_FLASH_LOCK_TOUT
1870		Timeout for Flash set sector lock bit operation (in ms)
1871
1872- CFG_FLASH_UNLOCK_TOUT
1873		Timeout for Flash clear lock bits operation (in ms)
1874
1875- CFG_FLASH_PROTECTION
1876		If defined, hardware flash sectors protection is used
1877		instead of U-Boot software protection.
1878
1879- CFG_DIRECT_FLASH_TFTP:
1880
1881		Enable TFTP transfers directly to flash memory;
1882		without this option such a download has to be
1883		performed in two steps: (1) download to RAM, and (2)
1884		copy from RAM to flash.
1885
1886		The two-step approach is usually more reliable, since
1887		you can check if the download worked before you erase
1888		the flash, but in some situations (when sytem RAM is
1889		too limited to allow for a tempory copy of the
1890		downloaded image) this option may be very useful.
1891
1892- CFG_FLASH_CFI:
1893		Define if the flash driver uses extra elements in the
1894		common flash structure for storing flash geometry.
1895
1896- CFG_FLASH_CFI_DRIVER
1897		This option also enables the building of the cfi_flash driver
1898		in the drivers directory
1899
1900- CFG_FLASH_QUIET_TEST
1901		If this option is defined, the common CFI flash doesn't
1902		print it's warning upon not recognized FLASH banks. This
1903		is useful, if some of the configured banks are only
1904		optionally available.
1905
1906- CFG_RX_ETH_BUFFER:
1907		Defines the number of ethernet receive buffers. On some
1908		ethernet controllers it is recommended to set this value
1909		to 8 or even higher (EEPRO100 or 405 EMAC), since all
1910		buffers can be full shortly after enabling the interface
1911		on high ethernet traffic.
1912		Defaults to 4 if not defined.
1913
1914The following definitions that deal with the placement and management
1915of environment data (variable area); in general, we support the
1916following configurations:
1917
1918- CFG_ENV_IS_IN_FLASH:
1919
1920	Define this if the environment is in flash memory.
1921
1922	a) The environment occupies one whole flash sector, which is
1923	   "embedded" in the text segment with the U-Boot code. This
1924	   happens usually with "bottom boot sector" or "top boot
1925	   sector" type flash chips, which have several smaller
1926	   sectors at the start or the end. For instance, such a
1927	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
1928	   such a case you would place the environment in one of the
1929	   4 kB sectors - with U-Boot code before and after it. With
1930	   "top boot sector" type flash chips, you would put the
1931	   environment in one of the last sectors, leaving a gap
1932	   between U-Boot and the environment.
1933
1934	- CFG_ENV_OFFSET:
1935
1936	   Offset of environment data (variable area) to the
1937	   beginning of flash memory; for instance, with bottom boot
1938	   type flash chips the second sector can be used: the offset
1939	   for this sector is given here.
1940
1941	   CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
1942
1943	- CFG_ENV_ADDR:
1944
1945	   This is just another way to specify the start address of
1946	   the flash sector containing the environment (instead of
1947	   CFG_ENV_OFFSET).
1948
1949	- CFG_ENV_SECT_SIZE:
1950
1951	   Size of the sector containing the environment.
1952
1953
1954	b) Sometimes flash chips have few, equal sized, BIG sectors.
1955	   In such a case you don't want to spend a whole sector for
1956	   the environment.
1957
1958	- CFG_ENV_SIZE:
1959
1960	   If you use this in combination with CFG_ENV_IS_IN_FLASH
1961	   and CFG_ENV_SECT_SIZE, you can specify to use only a part
1962	   of this flash sector for the environment. This saves
1963	   memory for the RAM copy of the environment.
1964
1965	   It may also save flash memory if you decide to use this
1966	   when your environment is "embedded" within U-Boot code,
1967	   since then the remainder of the flash sector could be used
1968	   for U-Boot code. It should be pointed out that this is
1969	   STRONGLY DISCOURAGED from a robustness point of view:
1970	   updating the environment in flash makes it always
1971	   necessary to erase the WHOLE sector. If something goes
1972	   wrong before the contents has been restored from a copy in
1973	   RAM, your target system will be dead.
1974
1975	- CFG_ENV_ADDR_REDUND
1976	  CFG_ENV_SIZE_REDUND
1977
1978	   These settings describe a second storage area used to hold
1979	   a redundand copy of the environment data, so that there is
1980	   a valid backup copy in case there is a power failure during
1981	   a "saveenv" operation.
1982
1983BE CAREFUL! Any changes to the flash layout, and some changes to the
1984source code will make it necessary to adapt <board>/u-boot.lds*
1985accordingly!
1986
1987
1988- CFG_ENV_IS_IN_NVRAM:
1989
1990	Define this if you have some non-volatile memory device
1991	(NVRAM, battery buffered SRAM) which you want to use for the
1992	environment.
1993
1994	- CFG_ENV_ADDR:
1995	- CFG_ENV_SIZE:
1996
1997	  These two #defines are used to determin the memory area you
1998	  want to use for environment. It is assumed that this memory
1999	  can just be read and written to, without any special
2000	  provision.
2001
2002BE CAREFUL! The first access to the environment happens quite early
2003in U-Boot initalization (when we try to get the setting of for the
2004console baudrate). You *MUST* have mappend your NVRAM area then, or
2005U-Boot will hang.
2006
2007Please note that even with NVRAM we still use a copy of the
2008environment in RAM: we could work on NVRAM directly, but we want to
2009keep settings there always unmodified except somebody uses "saveenv"
2010to save the current settings.
2011
2012
2013- CFG_ENV_IS_IN_EEPROM:
2014
2015	Use this if you have an EEPROM or similar serial access
2016	device and a driver for it.
2017
2018	- CFG_ENV_OFFSET:
2019	- CFG_ENV_SIZE:
2020
2021	  These two #defines specify the offset and size of the
2022	  environment area within the total memory of your EEPROM.
2023
2024	- CFG_I2C_EEPROM_ADDR:
2025	  If defined, specified the chip address of the EEPROM device.
2026	  The default address is zero.
2027
2028	- CFG_EEPROM_PAGE_WRITE_BITS:
2029	  If defined, the number of bits used to address bytes in a
2030	  single page in the EEPROM device.  A 64 byte page, for example
2031	  would require six bits.
2032
2033	- CFG_EEPROM_PAGE_WRITE_DELAY_MS:
2034	  If defined, the number of milliseconds to delay between
2035	  page writes.	The default is zero milliseconds.
2036
2037	- CFG_I2C_EEPROM_ADDR_LEN:
2038	  The length in bytes of the EEPROM memory array address.  Note
2039	  that this is NOT the chip address length!
2040
2041	- CFG_I2C_EEPROM_ADDR_OVERFLOW:
2042	  EEPROM chips that implement "address overflow" are ones
2043	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
2044	  address and the extra bits end up in the "chip address" bit
2045	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
2046	  byte chips.
2047
2048	  Note that we consider the length of the address field to
2049	  still be one byte because the extra address bits are hidden
2050	  in the chip address.
2051
2052	- CFG_EEPROM_SIZE:
2053	  The size in bytes of the EEPROM device.
2054
2055
2056- CFG_ENV_IS_IN_DATAFLASH:
2057
2058	Define this if you have a DataFlash memory device which you
2059	want to use for the environment.
2060
2061	- CFG_ENV_OFFSET:
2062	- CFG_ENV_ADDR:
2063	- CFG_ENV_SIZE:
2064
2065	  These three #defines specify the offset and size of the
2066	  environment area within the total memory of your DataFlash placed
2067	  at the specified address.
2068
2069- CFG_ENV_IS_IN_NAND:
2070
2071	Define this if you have a NAND device which you want to use
2072	for the environment.
2073
2074	- CFG_ENV_OFFSET:
2075	- CFG_ENV_SIZE:
2076
2077	  These two #defines specify the offset and size of the environment
2078	  area within the first NAND device.
2079
2080	- CFG_ENV_OFFSET_REDUND
2081
2082	  This setting describes a second storage area of CFG_ENV_SIZE
2083	  size used to hold a redundant copy of the environment data,
2084	  so that there is a valid backup copy in case there is a
2085	  power failure during a "saveenv" operation.
2086
2087	Note: CFG_ENV_OFFSET and CFG_ENV_OFFSET_REDUND must be aligned
2088	to a block boundary, and CFG_ENV_SIZE must be a multiple of
2089	the NAND devices block size.
2090
2091- CFG_SPI_INIT_OFFSET
2092
2093	Defines offset to the initial SPI buffer area in DPRAM. The
2094	area is used at an early stage (ROM part) if the environment
2095	is configured to reside in the SPI EEPROM: We need a 520 byte
2096	scratch DPRAM area. It is used between the two initialization
2097	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
2098	to be a good choice since it makes it far enough from the
2099	start of the data area as well as from the stack pointer.
2100
2101Please note that the environment is read-only as long as the monitor
2102has been relocated to RAM and a RAM copy of the environment has been
2103created; also, when using EEPROM you will have to use getenv_r()
2104until then to read environment variables.
2105
2106The environment is protected by a CRC32 checksum. Before the monitor
2107is relocated into RAM, as a result of a bad CRC you will be working
2108with the compiled-in default environment - *silently*!!! [This is
2109necessary, because the first environment variable we need is the
2110"baudrate" setting for the console - if we have a bad CRC, we don't
2111have any device yet where we could complain.]
2112
2113Note: once the monitor has been relocated, then it will complain if
2114the default environment is used; a new CRC is computed as soon as you
2115use the "saveenv" command to store a valid environment.
2116
2117- CFG_FAULT_ECHO_LINK_DOWN:
2118		Echo the inverted Ethernet link state to the fault LED.
2119
2120		Note: If this option is active, then CFG_FAULT_MII_ADDR
2121		      also needs to be defined.
2122
2123- CFG_FAULT_MII_ADDR:
2124		MII address of the PHY to check for the Ethernet link state.
2125
2126- CFG_64BIT_VSPRINTF:
2127		Makes vsprintf (and all *printf functions) support printing
2128		of 64bit values by using the L quantifier
2129
2130- CFG_64BIT_STRTOUL:
2131		Adds simple_strtoull that returns a 64bit value
2132
2133Low Level (hardware related) configuration options:
2134---------------------------------------------------
2135
2136- CFG_CACHELINE_SIZE:
2137		Cache Line Size of the CPU.
2138
2139- CFG_DEFAULT_IMMR:
2140		Default address of the IMMR after system reset.
2141
2142		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
2143		and RPXsuper) to be able to adjust the position of
2144		the IMMR register after a reset.
2145
2146- Floppy Disk Support:
2147		CFG_FDC_DRIVE_NUMBER
2148
2149		the default drive number (default value 0)
2150
2151		CFG_ISA_IO_STRIDE
2152
2153		defines the spacing between fdc chipset registers
2154		(default value 1)
2155
2156		CFG_ISA_IO_OFFSET
2157
2158		defines the offset of register from address. It
2159		depends on which part of the data bus is connected to
2160		the fdc chipset. (default value 0)
2161
2162		If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
2163		CFG_FDC_DRIVE_NUMBER are undefined, they take their
2164		default value.
2165
2166		if CFG_FDC_HW_INIT is defined, then the function
2167		fdc_hw_init() is called at the beginning of the FDC
2168		setup. fdc_hw_init() must be provided by the board
2169		source code. It is used to make hardware dependant
2170		initializations.
2171
2172- CFG_IMMR:	Physical address of the Internal Memory.
2173		DO NOT CHANGE unless you know exactly what you're
2174		doing! (11-4) [MPC8xx/82xx systems only]
2175
2176- CFG_INIT_RAM_ADDR:
2177
2178		Start address of memory area that can be used for
2179		initial data and stack; please note that this must be
2180		writable memory that is working WITHOUT special
2181		initialization, i. e. you CANNOT use normal RAM which
2182		will become available only after programming the
2183		memory controller and running certain initialization
2184		sequences.
2185
2186		U-Boot uses the following memory types:
2187		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
2188		- MPC824X: data cache
2189		- PPC4xx:  data cache
2190
2191- CFG_GBL_DATA_OFFSET:
2192
2193		Offset of the initial data structure in the memory
2194		area defined by CFG_INIT_RAM_ADDR. Usually
2195		CFG_GBL_DATA_OFFSET is chosen such that the initial
2196		data is located at the end of the available space
2197		(sometimes written as (CFG_INIT_RAM_END -
2198		CFG_INIT_DATA_SIZE), and the initial stack is just
2199		below that area (growing from (CFG_INIT_RAM_ADDR +
2200		CFG_GBL_DATA_OFFSET) downward.
2201
2202	Note:
2203		On the MPC824X (or other systems that use the data
2204		cache for initial memory) the address chosen for
2205		CFG_INIT_RAM_ADDR is basically arbitrary - it must
2206		point to an otherwise UNUSED address space between
2207		the top of RAM and the start of the PCI space.
2208
2209- CFG_SIUMCR:	SIU Module Configuration (11-6)
2210
2211- CFG_SYPCR:	System Protection Control (11-9)
2212
2213- CFG_TBSCR:	Time Base Status and Control (11-26)
2214
2215- CFG_PISCR:	Periodic Interrupt Status and Control (11-31)
2216
2217- CFG_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
2218
2219- CFG_SCCR:	System Clock and reset Control Register (15-27)
2220
2221- CFG_OR_TIMING_SDRAM:
2222		SDRAM timing
2223
2224- CFG_MAMR_PTA:
2225		periodic timer for refresh
2226
2227- CFG_DER:	Debug Event Register (37-47)
2228
2229- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
2230  CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
2231  CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
2232  CFG_BR1_PRELIM:
2233		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2234
2235- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2236  CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
2237  CFG_OR3_PRELIM, CFG_BR3_PRELIM:
2238		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2239
2240- CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
2241  CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
2242		Machine Mode Register and Memory Periodic Timer
2243		Prescaler definitions (SDRAM timing)
2244
2245- CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
2246		enable I2C microcode relocation patch (MPC8xx);
2247		define relocation offset in DPRAM [DSP2]
2248
2249- CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
2250		enable SPI microcode relocation patch (MPC8xx);
2251		define relocation offset in DPRAM [SCC4]
2252
2253- CFG_USE_OSCCLK:
2254		Use OSCM clock mode on MBX8xx board. Be careful,
2255		wrong setting might damage your board. Read
2256		doc/README.MBX before setting this variable!
2257
2258- CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
2259		Offset of the bootmode word in DPRAM used by post
2260		(Power On Self Tests). This definition overrides
2261		#define'd default value in commproc.h resp.
2262		cpm_8260.h.
2263
2264- CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
2265  CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
2266  CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
2267  CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
2268  CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
2269  CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
2270  CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
2271  CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
2272		Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
2273
2274- CONFIG_ETHER_ON_FEC[12]
2275		Define to enable FEC[12] on a 8xx series processor.
2276
2277- CONFIG_FEC[12]_PHY
2278		Define to the hardcoded PHY address which corresponds
2279		to the given FEC; i. e.
2280			#define CONFIG_FEC1_PHY 4
2281		means that the PHY with address 4 is connected to FEC1
2282
2283		When set to -1, means to probe for first available.
2284
2285- CONFIG_FEC[12]_PHY_NORXERR
2286		The PHY does not have a RXERR line (RMII only).
2287		(so program the FEC to ignore it).
2288
2289- CONFIG_RMII
2290		Enable RMII mode for all FECs.
2291		Note that this is a global option, we can't
2292		have one FEC in standard MII mode and another in RMII mode.
2293
2294- CONFIG_CRC32_VERIFY
2295		Add a verify option to the crc32 command.
2296		The syntax is:
2297
2298		=> crc32 -v <address> <count> <crc32>
2299
2300		Where address/count indicate a memory area
2301		and crc32 is the correct crc32 which the
2302		area should have.
2303
2304- CONFIG_LOOPW
2305		Add the "loopw" memory command. This only takes effect if
2306		the memory commands are activated globally (CFG_CMD_MEM).
2307
2308- CONFIG_MX_CYCLIC
2309		Add the "mdc" and "mwc" memory commands. These are cyclic
2310		"md/mw" commands.
2311		Examples:
2312
2313		=> mdc.b 10 4 500
2314		This command will print 4 bytes (10,11,12,13) each 500 ms.
2315
2316		=> mwc.l 100 12345678 10
2317		This command will write 12345678 to address 100 all 10 ms.
2318
2319		This only takes effect if the memory commands are activated
2320		globally (CFG_CMD_MEM).
2321
2322- CONFIG_SKIP_LOWLEVEL_INIT
2323- CONFIG_SKIP_RELOCATE_UBOOT
2324
2325		[ARM only] If these variables are defined, then
2326		certain low level initializations (like setting up
2327		the memory controller) are omitted and/or U-Boot does
2328		not relocate itself into RAM.
2329		Normally these variables MUST NOT be defined. The
2330		only exception is when U-Boot is loaded (to RAM) by
2331		some other boot loader or by a debugger which
2332		performs these intializations itself.
2333
2334
2335Building the Software:
2336======================
2337
2338Building U-Boot has been tested in native PPC environments (on a
2339PowerBook G3 running LinuxPPC 2000) and in cross environments
2340(running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
2341NetBSD 1.5 on x86).
2342
2343If you are not using a native PPC environment, it is assumed that you
2344have the GNU cross compiling tools available in your path and named
2345with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
2346you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
2347the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
2348change it to:
2349
2350	CROSS_COMPILE = ppc_4xx-
2351
2352
2353U-Boot is intended to be  simple  to  build.  After  installing	 the
2354sources	 you must configure U-Boot for one specific board type. This
2355is done by typing:
2356
2357	make NAME_config
2358
2359where "NAME_config" is the name of one of the existing
2360configurations; the following names are supported:
2361
2362	ADCIOP_config		FPS860L_config		omap730p2_config
2363	ADS860_config		GEN860T_config		pcu_e_config
2364	Alaska8220_config
2365	AR405_config		GENIETV_config		PIP405_config
2366	at91rm9200dk_config	GTH_config		QS823_config
2367	CANBT_config		hermes_config		QS850_config
2368	cmi_mpc5xx_config	hymod_config		QS860T_config
2369	cogent_common_config	IP860_config		RPXlite_config
2370	cogent_mpc8260_config	IVML24_config		RPXlite_DW_config
2371	cogent_mpc8xx_config	IVMS8_config		RPXsuper_config
2372	CPCI405_config		JSE_config		rsdproto_config
2373	CPCIISER4_config	LANTEC_config		Sandpoint8240_config
2374	csb272_config		lwmon_config		sbc8260_config
2375	CU824_config		MBX860T_config		sbc8560_33_config
2376	DUET_ADS_config		MBX_config		sbc8560_66_config
2377	EBONY_config		MPC8260ADS_config	SM850_config
2378	ELPT860_config		MPC8540ADS_config	SPD823TS_config
2379	ESTEEM192E_config	MPC8540EVAL_config	stxgp3_config
2380	ETX094_config		MPC8560ADS_config	SXNI855T_config
2381	FADS823_config		NETVIA_config		TQM823L_config
2382	FADS850SAR_config	omap1510inn_config	TQM850L_config
2383	FADS860T_config		omap1610h2_config	TQM855L_config
2384	FPS850L_config		omap1610inn_config	TQM860L_config
2385				omap5912osk_config	walnut_config
2386				omap2420h4_config	Yukon8220_config
2387							ZPC1900_config
2388
2389Note: for some board special configuration names may exist; check if
2390      additional information is available from the board vendor; for
2391      instance, the TQM823L systems are available without (standard)
2392      or with LCD support. You can select such additional "features"
2393      when chosing the configuration, i. e.
2394
2395      make TQM823L_config
2396	- will configure for a plain TQM823L, i. e. no LCD support
2397
2398      make TQM823L_LCD_config
2399	- will configure for a TQM823L with U-Boot console on LCD
2400
2401      etc.
2402
2403
2404Finally, type "make all", and you should get some working U-Boot
2405images ready for download to / installation on your system:
2406
2407- "u-boot.bin" is a raw binary image
2408- "u-boot" is an image in ELF binary format
2409- "u-boot.srec" is in Motorola S-Record format
2410
2411By default the build is performed locally and the objects are saved
2412in the source directory. One of the two methods can be used to change
2413this behavior and build U-Boot to some external directory:
2414
24151. Add O= to the make command line invocations:
2416
2417	make O=/tmp/build distclean
2418	make O=/tmp/build NAME_config
2419	make O=/tmp/build all
2420
24212. Set environment variable BUILD_DIR to point to the desired location:
2422
2423	export BUILD_DIR=/tmp/build
2424	make distclean
2425	make NAME_config
2426	make all
2427
2428Note that the command line "O=" setting overrides the BUILD_DIR environment
2429variable.
2430
2431
2432Please be aware that the Makefiles assume you are using GNU make, so
2433for instance on NetBSD you might need to use "gmake" instead of
2434native "make".
2435
2436
2437If the system board that you have is not listed, then you will need
2438to port U-Boot to your hardware platform. To do this, follow these
2439steps:
2440
24411.  Add a new configuration option for your board to the toplevel
2442    "Makefile" and to the "MAKEALL" script, using the existing
2443    entries as examples. Note that here and at many other places
2444    boards and other names are listed in alphabetical sort order. Please
2445    keep this order.
24462.  Create a new directory to hold your board specific code. Add any
2447    files you need. In your board directory, you will need at least
2448    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
24493.  Create a new configuration file "include/configs/<board>.h" for
2450    your board
24513.  If you're porting U-Boot to a new CPU, then also create a new
2452    directory to hold your CPU specific code. Add any files you need.
24534.  Run "make <board>_config" with your new name.
24545.  Type "make", and you should get a working "u-boot.srec" file
2455    to be installed on your target system.
24566.  Debug and solve any problems that might arise.
2457    [Of course, this last step is much harder than it sounds.]
2458
2459
2460Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2461==============================================================
2462
2463If you have modified U-Boot sources (for instance added a new	board
2464or  support  for  new  devices,	 a new CPU, etc.) you are expected to
2465provide feedback to the other developers. The feedback normally takes
2466the form of a "patch", i. e. a context diff against a certain (latest
2467official or latest in CVS) version of U-Boot sources.
2468
2469But before you submit such a patch, please verify that	your  modifi-
2470cation	did not break existing code. At least make sure that *ALL* of
2471the supported boards compile WITHOUT ANY compiler warnings. To do so,
2472just run the "MAKEALL" script, which will configure and build U-Boot
2473for ALL supported system. Be warned, this will take a while. You  can
2474select	which  (cross)	compiler  to use by passing a `CROSS_COMPILE'
2475environment variable to the script, i. e. to use the cross tools from
2476MontaVista's Hard Hat Linux you can type
2477
2478	CROSS_COMPILE=ppc_8xx- MAKEALL
2479
2480or to build on a native PowerPC system you can type
2481
2482	CROSS_COMPILE=' ' MAKEALL
2483
2484When using the MAKEALL script, the default behaviour is to build U-Boot
2485in the source directory. This location can be changed by setting the
2486BUILD_DIR environment variable. Also, for each target built, the MAKEALL
2487script saves two log files (<target>.ERR and <target>.MAKEALL) in the
2488<source dir>/LOG directory. This default location can be changed by
2489setting the MAKEALL_LOGDIR environment variable. For example:
2490
2491	export BUILD_DIR=/tmp/build
2492	export MAKEALL_LOGDIR=/tmp/log
2493	CROSS_COMPILE=ppc_8xx- MAKEALL
2494
2495With the above settings build objects are saved in the /tmp/build, log
2496files are saved in the /tmp/log and the source tree remains clean during
2497the whole build process.
2498
2499
2500See also "U-Boot Porting Guide" below.
2501
2502
2503Monitor Commands - Overview:
2504============================
2505
2506go	- start application at address 'addr'
2507run	- run commands in an environment variable
2508bootm	- boot application image from memory
2509bootp	- boot image via network using BootP/TFTP protocol
2510tftpboot- boot image via network using TFTP protocol
2511	       and env variables "ipaddr" and "serverip"
2512	       (and eventually "gatewayip")
2513rarpboot- boot image via network using RARP/TFTP protocol
2514diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
2515loads	- load S-Record file over serial line
2516loadb	- load binary file over serial line (kermit mode)
2517md	- memory display
2518mm	- memory modify (auto-incrementing)
2519nm	- memory modify (constant address)
2520mw	- memory write (fill)
2521cp	- memory copy
2522cmp	- memory compare
2523crc32	- checksum calculation
2524imd	- i2c memory display
2525imm	- i2c memory modify (auto-incrementing)
2526inm	- i2c memory modify (constant address)
2527imw	- i2c memory write (fill)
2528icrc32	- i2c checksum calculation
2529iprobe	- probe to discover valid I2C chip addresses
2530iloop	- infinite loop on address range
2531isdram	- print SDRAM configuration information
2532sspi	- SPI utility commands
2533base	- print or set address offset
2534printenv- print environment variables
2535setenv	- set environment variables
2536saveenv - save environment variables to persistent storage
2537protect - enable or disable FLASH write protection
2538erase	- erase FLASH memory
2539flinfo	- print FLASH memory information
2540bdinfo	- print Board Info structure
2541iminfo	- print header information for application image
2542coninfo - print console devices and informations
2543ide	- IDE sub-system
2544loop	- infinite loop on address range
2545loopw	- infinite write loop on address range
2546mtest	- simple RAM test
2547icache	- enable or disable instruction cache
2548dcache	- enable or disable data cache
2549reset	- Perform RESET of the CPU
2550echo	- echo args to console
2551version - print monitor version
2552help	- print online help
2553?	- alias for 'help'
2554
2555
2556Monitor Commands - Detailed Description:
2557========================================
2558
2559TODO.
2560
2561For now: just type "help <command>".
2562
2563
2564Environment Variables:
2565======================
2566
2567U-Boot supports user configuration using Environment Variables which
2568can be made persistent by saving to Flash memory.
2569
2570Environment Variables are set using "setenv", printed using
2571"printenv", and saved to Flash using "saveenv". Using "setenv"
2572without a value can be used to delete a variable from the
2573environment. As long as you don't save the environment you are
2574working with an in-memory copy. In case the Flash area containing the
2575environment is erased by accident, a default environment is provided.
2576
2577Some configuration options can be set using Environment Variables:
2578
2579  baudrate	- see CONFIG_BAUDRATE
2580
2581  bootdelay	- see CONFIG_BOOTDELAY
2582
2583  bootcmd	- see CONFIG_BOOTCOMMAND
2584
2585  bootargs	- Boot arguments when booting an RTOS image
2586
2587  bootfile	- Name of the image to load with TFTP
2588
2589  autoload	- if set to "no" (any string beginning with 'n'),
2590		  "bootp" will just load perform a lookup of the
2591		  configuration from the BOOTP server, but not try to
2592		  load any image using TFTP
2593
2594  autostart	- if set to "yes", an image loaded using the "bootp",
2595		  "rarpboot", "tftpboot" or "diskboot" commands will
2596		  be automatically started (by internally calling
2597		  "bootm")
2598
2599		  If set to "no", a standalone image passed to the
2600		  "bootm" command will be copied to the load address
2601		  (and eventually uncompressed), but NOT be started.
2602		  This can be used to load and uncompress arbitrary
2603		  data.
2604
2605  i2cfast	- (PPC405GP|PPC405EP only)
2606		  if set to 'y' configures Linux I2C driver for fast
2607		  mode (400kHZ). This environment variable is used in
2608		  initialization code. So, for changes to be effective
2609		  it must be saved and board must be reset.
2610
2611  initrd_high	- restrict positioning of initrd images:
2612		  If this variable is not set, initrd images will be
2613		  copied to the highest possible address in RAM; this
2614		  is usually what you want since it allows for
2615		  maximum initrd size. If for some reason you want to
2616		  make sure that the initrd image is loaded below the
2617		  CFG_BOOTMAPSZ limit, you can set this environment
2618		  variable to a value of "no" or "off" or "0".
2619		  Alternatively, you can set it to a maximum upper
2620		  address to use (U-Boot will still check that it
2621		  does not overwrite the U-Boot stack and data).
2622
2623		  For instance, when you have a system with 16 MB
2624		  RAM, and want to reserve 4 MB from use by Linux,
2625		  you can do this by adding "mem=12M" to the value of
2626		  the "bootargs" variable. However, now you must make
2627		  sure that the initrd image is placed in the first
2628		  12 MB as well - this can be done with
2629
2630		  setenv initrd_high 00c00000
2631
2632		  If you set initrd_high to 0xFFFFFFFF, this is an
2633		  indication to U-Boot that all addresses are legal
2634		  for the Linux kernel, including addresses in flash
2635		  memory. In this case U-Boot will NOT COPY the
2636		  ramdisk at all. This may be useful to reduce the
2637		  boot time on your system, but requires that this
2638		  feature is supported by your Linux kernel.
2639
2640  ipaddr	- IP address; needed for tftpboot command
2641
2642  loadaddr	- Default load address for commands like "bootp",
2643		  "rarpboot", "tftpboot", "loadb" or "diskboot"
2644
2645  loads_echo	- see CONFIG_LOADS_ECHO
2646
2647  serverip	- TFTP server IP address; needed for tftpboot command
2648
2649  bootretry	- see CONFIG_BOOT_RETRY_TIME
2650
2651  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
2652
2653  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
2654
2655  ethprime	- When CONFIG_NET_MULTI is enabled controls which
2656		  interface is used first.
2657
2658  ethact	- When CONFIG_NET_MULTI is enabled controls which
2659		  interface is currently active. For example you
2660		  can do the following
2661
2662		  => setenv ethact FEC ETHERNET
2663		  => ping 192.168.0.1 # traffic sent on FEC ETHERNET
2664		  => setenv ethact SCC ETHERNET
2665		  => ping 10.0.0.1 # traffic sent on SCC ETHERNET
2666
2667   netretry	- When set to "no" each network operation will
2668		  either succeed or fail without retrying.
2669		  When set to "once" the network operation will
2670		  fail when all the available network interfaces
2671		  are tried once without success.
2672		  Useful on scripts which control the retry operation
2673		  themselves.
2674
2675  tftpsrcport	- If this is set, the value is used for TFTP's
2676		  UDP source port.
2677
2678  tftpdstport	- If this is set, the value is used for TFTP's UDP
2679		  destination port instead of the Well Know Port 69.
2680
2681   vlan		- When set to a value < 4095 the traffic over
2682		  ethernet is encapsulated/received over 802.1q
2683		  VLAN tagged frames.
2684
2685The following environment variables may be used and automatically
2686updated by the network boot commands ("bootp" and "rarpboot"),
2687depending the information provided by your boot server:
2688
2689  bootfile	- see above
2690  dnsip		- IP address of your Domain Name Server
2691  dnsip2	- IP address of your secondary Domain Name Server
2692  gatewayip	- IP address of the Gateway (Router) to use
2693  hostname	- Target hostname
2694  ipaddr	- see above
2695  netmask	- Subnet Mask
2696  rootpath	- Pathname of the root filesystem on the NFS server
2697  serverip	- see above
2698
2699
2700There are two special Environment Variables:
2701
2702  serial#	- contains hardware identification information such
2703		  as type string and/or serial number
2704  ethaddr	- Ethernet address
2705
2706These variables can be set only once (usually during manufacturing of
2707the board). U-Boot refuses to delete or overwrite these variables
2708once they have been set once.
2709
2710
2711Further special Environment Variables:
2712
2713  ver		- Contains the U-Boot version string as printed
2714		  with the "version" command. This variable is
2715		  readonly (see CONFIG_VERSION_VARIABLE).
2716
2717
2718Please note that changes to some configuration parameters may take
2719only effect after the next boot (yes, that's just like Windoze :-).
2720
2721
2722Command Line Parsing:
2723=====================
2724
2725There are two different command line parsers available with U-Boot:
2726the old "simple" one, and the much more powerful "hush" shell:
2727
2728Old, simple command line parser:
2729--------------------------------
2730
2731- supports environment variables (through setenv / saveenv commands)
2732- several commands on one line, separated by ';'
2733- variable substitution using "... ${name} ..." syntax
2734- special characters ('$', ';') can be escaped by prefixing with '\',
2735  for example:
2736	setenv bootcmd bootm \${address}
2737- You can also escape text by enclosing in single apostrophes, for example:
2738	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
2739
2740Hush shell:
2741-----------
2742
2743- similar to Bourne shell, with control structures like
2744  if...then...else...fi, for...do...done; while...do...done,
2745  until...do...done, ...
2746- supports environment ("global") variables (through setenv / saveenv
2747  commands) and local shell variables (through standard shell syntax
2748  "name=value"); only environment variables can be used with "run"
2749  command
2750
2751General rules:
2752--------------
2753
2754(1) If a command line (or an environment variable executed by a "run"
2755    command) contains several commands separated by semicolon, and
2756    one of these commands fails, then the remaining commands will be
2757    executed anyway.
2758
2759(2) If you execute several variables with one call to run (i. e.
2760    calling run with a list af variables as arguments), any failing
2761    command will cause "run" to terminate, i. e. the remaining
2762    variables are not executed.
2763
2764Note for Redundant Ethernet Interfaces:
2765=======================================
2766
2767Some boards come with redundant ethernet interfaces; U-Boot supports
2768such configurations and is capable of automatic selection of a
2769"working" interface when needed. MAC assignment works as follows:
2770
2771Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2772MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2773"eth1addr" (=>eth1), "eth2addr", ...
2774
2775If the network interface stores some valid MAC address (for instance
2776in SROM), this is used as default address if there is NO correspon-
2777ding setting in the environment; if the corresponding environment
2778variable is set, this overrides the settings in the card; that means:
2779
2780o If the SROM has a valid MAC address, and there is no address in the
2781  environment, the SROM's address is used.
2782
2783o If there is no valid address in the SROM, and a definition in the
2784  environment exists, then the value from the environment variable is
2785  used.
2786
2787o If both the SROM and the environment contain a MAC address, and
2788  both addresses are the same, this MAC address is used.
2789
2790o If both the SROM and the environment contain a MAC address, and the
2791  addresses differ, the value from the environment is used and a
2792  warning is printed.
2793
2794o If neither SROM nor the environment contain a MAC address, an error
2795  is raised.
2796
2797
2798Image Formats:
2799==============
2800
2801The "boot" commands of this monitor operate on "image" files which
2802can be basicly anything, preceeded by a special header; see the
2803definitions in include/image.h for details; basicly, the header
2804defines the following image properties:
2805
2806* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2807  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2808  LynxOS, pSOS, QNX, RTEMS, ARTOS;
2809  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, ARTOS, LynxOS).
2810* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
2811  IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2812  Currently supported: ARM, AVR32, Intel x86, MIPS, NIOS, PowerPC).
2813* Compression Type (uncompressed, gzip, bzip2)
2814* Load Address
2815* Entry Point
2816* Image Name
2817* Image Timestamp
2818
2819The header is marked by a special Magic Number, and both the header
2820and the data portions of the image are secured against corruption by
2821CRC32 checksums.
2822
2823
2824Linux Support:
2825==============
2826
2827Although U-Boot should support any OS or standalone application
2828easily, the main focus has always been on Linux during the design of
2829U-Boot.
2830
2831U-Boot includes many features that so far have been part of some
2832special "boot loader" code within the Linux kernel. Also, any
2833"initrd" images to be used are no longer part of one big Linux image;
2834instead, kernel and "initrd" are separate images. This implementation
2835serves several purposes:
2836
2837- the same features can be used for other OS or standalone
2838  applications (for instance: using compressed images to reduce the
2839  Flash memory footprint)
2840
2841- it becomes much easier to port new Linux kernel versions because
2842  lots of low-level, hardware dependent stuff are done by U-Boot
2843
2844- the same Linux kernel image can now be used with different "initrd"
2845  images; of course this also means that different kernel images can
2846  be run with the same "initrd". This makes testing easier (you don't
2847  have to build a new "zImage.initrd" Linux image when you just
2848  change a file in your "initrd"). Also, a field-upgrade of the
2849  software is easier now.
2850
2851
2852Linux HOWTO:
2853============
2854
2855Porting Linux to U-Boot based systems:
2856---------------------------------------
2857
2858U-Boot cannot save you from doing all the necessary modifications to
2859configure the Linux device drivers for use with your target hardware
2860(no, we don't intend to provide a full virtual machine interface to
2861Linux :-).
2862
2863But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
2864
2865Just make sure your machine specific header file (for instance
2866include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2867Information structure as we define in include/u-boot.h, and make
2868sure that your definition of IMAP_ADDR uses the same value as your
2869U-Boot configuration in CFG_IMMR.
2870
2871
2872Configuring the Linux kernel:
2873-----------------------------
2874
2875No specific requirements for U-Boot. Make sure you have some root
2876device (initial ramdisk, NFS) for your target system.
2877
2878
2879Building a Linux Image:
2880-----------------------
2881
2882With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2883not used. If you use recent kernel source, a new build target
2884"uImage" will exist which automatically builds an image usable by
2885U-Boot. Most older kernels also have support for a "pImage" target,
2886which was introduced for our predecessor project PPCBoot and uses a
2887100% compatible format.
2888
2889Example:
2890
2891	make TQM850L_config
2892	make oldconfig
2893	make dep
2894	make uImage
2895
2896The "uImage" build target uses a special tool (in 'tools/mkimage') to
2897encapsulate a compressed Linux kernel image with header	 information,
2898CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2899
2900* build a standard "vmlinux" kernel image (in ELF binary format):
2901
2902* convert the kernel into a raw binary image:
2903
2904	${CROSS_COMPILE}-objcopy -O binary \
2905				 -R .note -R .comment \
2906				 -S vmlinux linux.bin
2907
2908* compress the binary image:
2909
2910	gzip -9 linux.bin
2911
2912* package compressed binary image for U-Boot:
2913
2914	mkimage -A ppc -O linux -T kernel -C gzip \
2915		-a 0 -e 0 -n "Linux Kernel Image" \
2916		-d linux.bin.gz uImage
2917
2918
2919The "mkimage" tool can also be used to create ramdisk images for use
2920with U-Boot, either separated from the Linux kernel image, or
2921combined into one file. "mkimage" encapsulates the images with a 64
2922byte header containing information about target architecture,
2923operating system, image type, compression method, entry points, time
2924stamp, CRC32 checksums, etc.
2925
2926"mkimage" can be called in two ways: to verify existing images and
2927print the header information, or to build new images.
2928
2929In the first form (with "-l" option) mkimage lists the information
2930contained in the header of an existing U-Boot image; this includes
2931checksum verification:
2932
2933	tools/mkimage -l image
2934	  -l ==> list image header information
2935
2936The second form (with "-d" option) is used to build a U-Boot image
2937from a "data file" which is used as image payload:
2938
2939	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2940		      -n name -d data_file image
2941	  -A ==> set architecture to 'arch'
2942	  -O ==> set operating system to 'os'
2943	  -T ==> set image type to 'type'
2944	  -C ==> set compression type 'comp'
2945	  -a ==> set load address to 'addr' (hex)
2946	  -e ==> set entry point to 'ep' (hex)
2947	  -n ==> set image name to 'name'
2948	  -d ==> use image data from 'datafile'
2949
2950Right now, all Linux kernels for PowerPC systems use the same load
2951address (0x00000000), but the entry point address depends on the
2952kernel version:
2953
2954- 2.2.x kernels have the entry point at 0x0000000C,
2955- 2.3.x and later kernels have the entry point at 0x00000000.
2956
2957So a typical call to build a U-Boot image would read:
2958
2959	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2960	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2961	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
2962	> examples/uImage.TQM850L
2963	Image Name:   2.4.4 kernel for TQM850L
2964	Created:      Wed Jul 19 02:34:59 2000
2965	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
2966	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
2967	Load Address: 0x00000000
2968	Entry Point:  0x00000000
2969
2970To verify the contents of the image (or check for corruption):
2971
2972	-> tools/mkimage -l examples/uImage.TQM850L
2973	Image Name:   2.4.4 kernel for TQM850L
2974	Created:      Wed Jul 19 02:34:59 2000
2975	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
2976	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
2977	Load Address: 0x00000000
2978	Entry Point:  0x00000000
2979
2980NOTE: for embedded systems where boot time is critical you can trade
2981speed for memory and install an UNCOMPRESSED image instead: this
2982needs more space in Flash, but boots much faster since it does not
2983need to be uncompressed:
2984
2985	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
2986	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2987	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2988	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
2989	> examples/uImage.TQM850L-uncompressed
2990	Image Name:   2.4.4 kernel for TQM850L
2991	Created:      Wed Jul 19 02:34:59 2000
2992	Image Type:   PowerPC Linux Kernel Image (uncompressed)
2993	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
2994	Load Address: 0x00000000
2995	Entry Point:  0x00000000
2996
2997
2998Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2999when your kernel is intended to use an initial ramdisk:
3000
3001	-> tools/mkimage -n 'Simple Ramdisk Image' \
3002	> -A ppc -O linux -T ramdisk -C gzip \
3003	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3004	Image Name:   Simple Ramdisk Image
3005	Created:      Wed Jan 12 14:01:50 2000
3006	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
3007	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
3008	Load Address: 0x00000000
3009	Entry Point:  0x00000000
3010
3011
3012Installing a Linux Image:
3013-------------------------
3014
3015To downloading a U-Boot image over the serial (console) interface,
3016you must convert the image to S-Record format:
3017
3018	objcopy -I binary -O srec examples/image examples/image.srec
3019
3020The 'objcopy' does not understand the information in the U-Boot
3021image header, so the resulting S-Record file will be relative to
3022address 0x00000000. To load it to a given address, you need to
3023specify the target address as 'offset' parameter with the 'loads'
3024command.
3025
3026Example: install the image to address 0x40100000 (which on the
3027TQM8xxL is in the first Flash bank):
3028
3029	=> erase 40100000 401FFFFF
3030
3031	.......... done
3032	Erased 8 sectors
3033
3034	=> loads 40100000
3035	## Ready for S-Record download ...
3036	~>examples/image.srec
3037	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3038	...
3039	15989 15990 15991 15992
3040	[file transfer complete]
3041	[connected]
3042	## Start Addr = 0x00000000
3043
3044
3045You can check the success of the download using the 'iminfo' command;
3046this includes a checksum verification so you  can  be  sure  no	 data
3047corruption happened:
3048
3049	=> imi 40100000
3050
3051	## Checking Image at 40100000 ...
3052	   Image Name:	 2.2.13 for initrd on TQM850L
3053	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3054	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3055	   Load Address: 00000000
3056	   Entry Point:	 0000000c
3057	   Verifying Checksum ... OK
3058
3059
3060Boot Linux:
3061-----------
3062
3063The "bootm" command is used to boot an application that is stored in
3064memory (RAM or Flash). In case of a Linux kernel image, the contents
3065of the "bootargs" environment variable is passed to the kernel as
3066parameters. You can check and modify this variable using the
3067"printenv" and "setenv" commands:
3068
3069
3070	=> printenv bootargs
3071	bootargs=root=/dev/ram
3072
3073	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3074
3075	=> printenv bootargs
3076	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3077
3078	=> bootm 40020000
3079	## Booting Linux kernel at 40020000 ...
3080	   Image Name:	 2.2.13 for NFS on TQM850L
3081	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3082	   Data Size:	 381681 Bytes = 372 kB = 0 MB
3083	   Load Address: 00000000
3084	   Entry Point:	 0000000c
3085	   Verifying Checksum ... OK
3086	   Uncompressing Kernel Image ... OK
3087	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
3088	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3089	time_init: decrementer frequency = 187500000/60
3090	Calibrating delay loop... 49.77 BogoMIPS
3091	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3092	...
3093
3094If you want to boot a Linux kernel with initial ram disk, you pass
3095the memory addresses of both the kernel and the initrd image (PPBCOOT
3096format!) to the "bootm" command:
3097
3098	=> imi 40100000 40200000
3099
3100	## Checking Image at 40100000 ...
3101	   Image Name:	 2.2.13 for initrd on TQM850L
3102	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3103	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3104	   Load Address: 00000000
3105	   Entry Point:	 0000000c
3106	   Verifying Checksum ... OK
3107
3108	## Checking Image at 40200000 ...
3109	   Image Name:	 Simple Ramdisk Image
3110	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3111	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3112	   Load Address: 00000000
3113	   Entry Point:	 00000000
3114	   Verifying Checksum ... OK
3115
3116	=> bootm 40100000 40200000
3117	## Booting Linux kernel at 40100000 ...
3118	   Image Name:	 2.2.13 for initrd on TQM850L
3119	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3120	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3121	   Load Address: 00000000
3122	   Entry Point:	 0000000c
3123	   Verifying Checksum ... OK
3124	   Uncompressing Kernel Image ... OK
3125	## Loading RAMDisk Image at 40200000 ...
3126	   Image Name:	 Simple Ramdisk Image
3127	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3128	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3129	   Load Address: 00000000
3130	   Entry Point:	 00000000
3131	   Verifying Checksum ... OK
3132	   Loading Ramdisk ... OK
3133	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
3134	Boot arguments: root=/dev/ram
3135	time_init: decrementer frequency = 187500000/60
3136	Calibrating delay loop... 49.77 BogoMIPS
3137	...
3138	RAMDISK: Compressed image found at block 0
3139	VFS: Mounted root (ext2 filesystem).
3140
3141	bash#
3142
3143Boot Linux and pass a flat device tree:
3144-----------
3145
3146First, U-Boot must be compiled with the appropriate defines. See the section
3147titled "Linux Kernel Interface" above for a more in depth explanation. The
3148following is an example of how to start a kernel and pass an updated
3149flat device tree:
3150
3151=> print oftaddr
3152oftaddr=0x300000
3153=> print oft
3154oft=oftrees/mpc8540ads.dtb
3155=> tftp $oftaddr $oft
3156Speed: 1000, full duplex
3157Using TSEC0 device
3158TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3159Filename 'oftrees/mpc8540ads.dtb'.
3160Load address: 0x300000
3161Loading: #
3162done
3163Bytes transferred = 4106 (100a hex)
3164=> tftp $loadaddr $bootfile
3165Speed: 1000, full duplex
3166Using TSEC0 device
3167TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3168Filename 'uImage'.
3169Load address: 0x200000
3170Loading:############
3171done
3172Bytes transferred = 1029407 (fb51f hex)
3173=> print loadaddr
3174loadaddr=200000
3175=> print oftaddr
3176oftaddr=0x300000
3177=> bootm $loadaddr - $oftaddr
3178## Booting image at 00200000 ...
3179   Image Name:	 Linux-2.6.17-dirty
3180   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3181   Data Size:	 1029343 Bytes = 1005.2 kB
3182   Load Address: 00000000
3183   Entry Point:	 00000000
3184   Verifying Checksum ... OK
3185   Uncompressing Kernel Image ... OK
3186Booting using flat device tree at 0x300000
3187Using MPC85xx ADS machine description
3188Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3189[snip]
3190
3191
3192More About U-Boot Image Types:
3193------------------------------
3194
3195U-Boot supports the following image types:
3196
3197   "Standalone Programs" are directly runnable in the environment
3198	provided by U-Boot; it is expected that (if they behave
3199	well) you can continue to work in U-Boot after return from
3200	the Standalone Program.
3201   "OS Kernel Images" are usually images of some Embedded OS which
3202	will take over control completely. Usually these programs
3203	will install their own set of exception handlers, device
3204	drivers, set up the MMU, etc. - this means, that you cannot
3205	expect to re-enter U-Boot except by resetting the CPU.
3206   "RAMDisk Images" are more or less just data blocks, and their
3207	parameters (address, size) are passed to an OS kernel that is
3208	being started.
3209   "Multi-File Images" contain several images, typically an OS
3210	(Linux) kernel image and one or more data images like
3211	RAMDisks. This construct is useful for instance when you want
3212	to boot over the network using BOOTP etc., where the boot
3213	server provides just a single image file, but you want to get
3214	for instance an OS kernel and a RAMDisk image.
3215
3216	"Multi-File Images" start with a list of image sizes, each
3217	image size (in bytes) specified by an "uint32_t" in network
3218	byte order. This list is terminated by an "(uint32_t)0".
3219	Immediately after the terminating 0 follow the images, one by
3220	one, all aligned on "uint32_t" boundaries (size rounded up to
3221	a multiple of 4 bytes).
3222
3223   "Firmware Images" are binary images containing firmware (like
3224	U-Boot or FPGA images) which usually will be programmed to
3225	flash memory.
3226
3227   "Script files" are command sequences that will be executed by
3228	U-Boot's command interpreter; this feature is especially
3229	useful when you configure U-Boot to use a real shell (hush)
3230	as command interpreter.
3231
3232
3233Standalone HOWTO:
3234=================
3235
3236One of the features of U-Boot is that you can dynamically load and
3237run "standalone" applications, which can use some resources of
3238U-Boot like console I/O functions or interrupt services.
3239
3240Two simple examples are included with the sources:
3241
3242"Hello World" Demo:
3243-------------------
3244
3245'examples/hello_world.c' contains a small "Hello World" Demo
3246application; it is automatically compiled when you build U-Boot.
3247It's configured to run at address 0x00040004, so you can play with it
3248like that:
3249
3250	=> loads
3251	## Ready for S-Record download ...
3252	~>examples/hello_world.srec
3253	1 2 3 4 5 6 7 8 9 10 11 ...
3254	[file transfer complete]
3255	[connected]
3256	## Start Addr = 0x00040004
3257
3258	=> go 40004 Hello World! This is a test.
3259	## Starting application at 0x00040004 ...
3260	Hello World
3261	argc = 7
3262	argv[0] = "40004"
3263	argv[1] = "Hello"
3264	argv[2] = "World!"
3265	argv[3] = "This"
3266	argv[4] = "is"
3267	argv[5] = "a"
3268	argv[6] = "test."
3269	argv[7] = "<NULL>"
3270	Hit any key to exit ...
3271
3272	## Application terminated, rc = 0x0
3273
3274Another example, which demonstrates how to register a CPM interrupt
3275handler with the U-Boot code, can be found in 'examples/timer.c'.
3276Here, a CPM timer is set up to generate an interrupt every second.
3277The interrupt service routine is trivial, just printing a '.'
3278character, but this is just a demo program. The application can be
3279controlled by the following keys:
3280
3281	? - print current values og the CPM Timer registers
3282	b - enable interrupts and start timer
3283	e - stop timer and disable interrupts
3284	q - quit application
3285
3286	=> loads
3287	## Ready for S-Record download ...
3288	~>examples/timer.srec
3289	1 2 3 4 5 6 7 8 9 10 11 ...
3290	[file transfer complete]
3291	[connected]
3292	## Start Addr = 0x00040004
3293
3294	=> go 40004
3295	## Starting application at 0x00040004 ...
3296	TIMERS=0xfff00980
3297	Using timer 1
3298	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3299
3300Hit 'b':
3301	[q, b, e, ?] Set interval 1000000 us
3302	Enabling timer
3303Hit '?':
3304	[q, b, e, ?] ........
3305	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3306Hit '?':
3307	[q, b, e, ?] .
3308	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3309Hit '?':
3310	[q, b, e, ?] .
3311	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3312Hit '?':
3313	[q, b, e, ?] .
3314	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3315Hit 'e':
3316	[q, b, e, ?] ...Stopping timer
3317Hit 'q':
3318	[q, b, e, ?] ## Application terminated, rc = 0x0
3319
3320
3321Minicom warning:
3322================
3323
3324Over time, many people have reported problems when trying to use the
3325"minicom" terminal emulation program for serial download. I (wd)
3326consider minicom to be broken, and recommend not to use it. Under
3327Unix, I recommend to use C-Kermit for general purpose use (and
3328especially for kermit binary protocol download ("loadb" command), and
3329use "cu" for S-Record download ("loads" command).
3330
3331Nevertheless, if you absolutely want to use it try adding this
3332configuration to your "File transfer protocols" section:
3333
3334	   Name	   Program			Name U/D FullScr IO-Red. Multi
3335	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
3336	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
3337
3338
3339NetBSD Notes:
3340=============
3341
3342Starting at version 0.9.2, U-Boot supports NetBSD both as host
3343(build U-Boot) and target system (boots NetBSD/mpc8xx).
3344
3345Building requires a cross environment; it is known to work on
3346NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3347need gmake since the Makefiles are not compatible with BSD make).
3348Note that the cross-powerpc package does not install include files;
3349attempting to build U-Boot will fail because <machine/ansi.h> is
3350missing.  This file has to be installed and patched manually:
3351
3352	# cd /usr/pkg/cross/powerpc-netbsd/include
3353	# mkdir powerpc
3354	# ln -s powerpc machine
3355	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3356	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
3357
3358Native builds *don't* work due to incompatibilities between native
3359and U-Boot include files.
3360
3361Booting assumes that (the first part of) the image booted is a
3362stage-2 loader which in turn loads and then invokes the kernel
3363proper. Loader sources will eventually appear in the NetBSD source
3364tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3365meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3366
3367
3368Implementation Internals:
3369=========================
3370
3371The following is not intended to be a complete description of every
3372implementation detail. However, it should help to understand the
3373inner workings of U-Boot and make it easier to port it to custom
3374hardware.
3375
3376
3377Initial Stack, Global Data:
3378---------------------------
3379
3380The implementation of U-Boot is complicated by the fact that U-Boot
3381starts running out of ROM (flash memory), usually without access to
3382system RAM (because the memory controller is not initialized yet).
3383This means that we don't have writable Data or BSS segments, and BSS
3384is not initialized as zero. To be able to get a C environment working
3385at all, we have to allocate at least a minimal stack. Implementation
3386options for this are defined and restricted by the CPU used: Some CPU
3387models provide on-chip memory (like the IMMR area on MPC8xx and
3388MPC826x processors), on others (parts of) the data cache can be
3389locked as (mis-) used as memory, etc.
3390
3391	Chris Hallinan posted a good summary of	 these	issues	to  the
3392	u-boot-users mailing list:
3393
3394	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3395	From: "Chris Hallinan" <clh@net1plus.com>
3396	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3397	...
3398
3399	Correct me if I'm wrong, folks, but the way I understand it
3400	is this: Using DCACHE as initial RAM for Stack, etc, does not
3401	require any physical RAM backing up the cache. The cleverness
3402	is that the cache is being used as a temporary supply of
3403	necessary storage before the SDRAM controller is setup. It's
3404	beyond the scope of this list to expain the details, but you
3405	can see how this works by studying the cache architecture and
3406	operation in the architecture and processor-specific manuals.
3407
3408	OCM is On Chip Memory, which I believe the 405GP has 4K. It
3409	is another option for the system designer to use as an
3410	initial stack/ram area prior to SDRAM being available. Either
3411	option should work for you. Using CS 4 should be fine if your
3412	board designers haven't used it for something that would
3413	cause you grief during the initial boot! It is frequently not
3414	used.
3415
3416	CFG_INIT_RAM_ADDR should be somewhere that won't interfere
3417	with your processor/board/system design. The default value
3418	you will find in any recent u-boot distribution in
3419	walnut.h should work for you. I'd set it to a value larger
3420	than your SDRAM module. If you have a 64MB SDRAM module, set
3421	it above 400_0000. Just make sure your board has no resources
3422	that are supposed to respond to that address! That code in
3423	start.S has been around a while and should work as is when
3424	you get the config right.
3425
3426	-Chris Hallinan
3427	DS4.COM, Inc.
3428
3429It is essential to remember this, since it has some impact on the C
3430code for the initialization procedures:
3431
3432* Initialized global data (data segment) is read-only. Do not attempt
3433  to write it.
3434
3435* Do not use any unitialized global data (or implicitely initialized
3436  as zero data - BSS segment) at all - this is undefined, initiali-
3437  zation is performed later (when relocating to RAM).
3438
3439* Stack space is very limited. Avoid big data buffers or things like
3440  that.
3441
3442Having only the stack as writable memory limits means we cannot use
3443normal global data to share information beween the code. But it
3444turned out that the implementation of U-Boot can be greatly
3445simplified by making a global data structure (gd_t) available to all
3446functions. We could pass a pointer to this data as argument to _all_
3447functions, but this would bloat the code. Instead we use a feature of
3448the GCC compiler (Global Register Variables) to share the data: we
3449place a pointer (gd) to the global data into a register which we
3450reserve for this purpose.
3451
3452When choosing a register for such a purpose we are restricted by the
3453relevant  (E)ABI  specifications for the current architecture, and by
3454GCC's implementation.
3455
3456For PowerPC, the following registers have specific use:
3457	R1:	stack pointer
3458	R2:	TOC pointer
3459	R3-R4:	parameter passing and return values
3460	R5-R10: parameter passing
3461	R13:	small data area pointer
3462	R30:	GOT pointer
3463	R31:	frame pointer
3464
3465	(U-Boot also uses R14 as internal GOT pointer.)
3466
3467    ==> U-Boot will use R29 to hold a pointer to the global data
3468
3469    Note: on PPC, we could use a static initializer (since the
3470    address of the global data structure is known at compile time),
3471    but it turned out that reserving a register results in somewhat
3472    smaller code - although the code savings are not that big (on
3473    average for all boards 752 bytes for the whole U-Boot image,
3474    624 text + 127 data).
3475
3476On ARM, the following registers are used:
3477
3478	R0:	function argument word/integer result
3479	R1-R3:	function argument word
3480	R9:	GOT pointer
3481	R10:	stack limit (used only if stack checking if enabled)
3482	R11:	argument (frame) pointer
3483	R12:	temporary workspace
3484	R13:	stack pointer
3485	R14:	link register
3486	R15:	program counter
3487
3488    ==> U-Boot will use R8 to hold a pointer to the global data
3489
3490NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3491or current versions of GCC may "optimize" the code too much.
3492
3493Memory Management:
3494------------------
3495
3496U-Boot runs in system state and uses physical addresses, i.e. the
3497MMU is not used either for address mapping nor for memory protection.
3498
3499The available memory is mapped to fixed addresses using the memory
3500controller. In this process, a contiguous block is formed for each
3501memory type (Flash, SDRAM, SRAM), even when it consists of several
3502physical memory banks.
3503
3504U-Boot is installed in the first 128 kB of the first Flash bank (on
3505TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3506booting and sizing and initializing DRAM, the code relocates itself
3507to the upper end of DRAM. Immediately below the U-Boot code some
3508memory is reserved for use by malloc() [see CFG_MALLOC_LEN
3509configuration setting]. Below that, a structure with global Board
3510Info data is placed, followed by the stack (growing downward).
3511
3512Additionally, some exception handler code is copied to the low 8 kB
3513of DRAM (0x00000000 ... 0x00001FFF).
3514
3515So a typical memory configuration with 16 MB of DRAM could look like
3516this:
3517
3518	0x0000 0000	Exception Vector code
3519	      :
3520	0x0000 1FFF
3521	0x0000 2000	Free for Application Use
3522	      :
3523	      :
3524
3525	      :
3526	      :
3527	0x00FB FF20	Monitor Stack (Growing downward)
3528	0x00FB FFAC	Board Info Data and permanent copy of global data
3529	0x00FC 0000	Malloc Arena
3530	      :
3531	0x00FD FFFF
3532	0x00FE 0000	RAM Copy of Monitor Code
3533	...		eventually: LCD or video framebuffer
3534	...		eventually: pRAM (Protected RAM - unchanged by reset)
3535	0x00FF FFFF	[End of RAM]
3536
3537
3538System Initialization:
3539----------------------
3540
3541In the reset configuration, U-Boot starts at the reset entry point
3542(on most PowerPC systens at address 0x00000100). Because of the reset
3543configuration for CS0# this is a mirror of the onboard Flash memory.
3544To be able to re-map memory U-Boot then jumps to its link address.
3545To be able to implement the initialization code in C, a (small!)
3546initial stack is set up in the internal Dual Ported RAM (in case CPUs
3547which provide such a feature like MPC8xx or MPC8260), or in a locked
3548part of the data cache. After that, U-Boot initializes the CPU core,
3549the caches and the SIU.
3550
3551Next, all (potentially) available memory banks are mapped using a
3552preliminary mapping. For example, we put them on 512 MB boundaries
3553(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3554on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3555programmed for SDRAM access. Using the temporary configuration, a
3556simple memory test is run that determines the size of the SDRAM
3557banks.
3558
3559When there is more than one SDRAM bank, and the banks are of
3560different size, the largest is mapped first. For equal size, the first
3561bank (CS2#) is mapped first. The first mapping is always for address
35620x00000000, with any additional banks following immediately to create
3563contiguous memory starting from 0.
3564
3565Then, the monitor installs itself at the upper end of the SDRAM area
3566and allocates memory for use by malloc() and for the global Board
3567Info data; also, the exception vector code is copied to the low RAM
3568pages, and the final stack is set up.
3569
3570Only after this relocation will you have a "normal" C environment;
3571until that you are restricted in several ways, mostly because you are
3572running from ROM, and because the code will have to be relocated to a
3573new address in RAM.
3574
3575
3576U-Boot Porting Guide:
3577----------------------
3578
3579[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3580list, October 2002]
3581
3582
3583int main (int argc, char *argv[])
3584{
3585	sighandler_t no_more_time;
3586
3587	signal (SIGALRM, no_more_time);
3588	alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
3589
3590	if (available_money > available_manpower) {
3591		pay consultant to port U-Boot;
3592		return 0;
3593	}
3594
3595	Download latest U-Boot source;
3596
3597	Subscribe to u-boot-users mailing list;
3598
3599	if (clueless) {
3600		email ("Hi, I am new to U-Boot, how do I get started?");
3601	}
3602
3603	while (learning) {
3604		Read the README file in the top level directory;
3605		Read http://www.denx.de/twiki/bin/view/DULG/Manual ;
3606		Read the source, Luke;
3607	}
3608
3609	if (available_money > toLocalCurrency ($2500)) {
3610		Buy a BDI2000;
3611	} else {
3612		Add a lot of aggravation and time;
3613	}
3614
3615	Create your own board support subdirectory;
3616
3617	Create your own board config file;
3618
3619	while (!running) {
3620		do {
3621			Add / modify source code;
3622		} until (compiles);
3623		Debug;
3624		if (clueless)
3625			email ("Hi, I am having problems...");
3626	}
3627	Send patch file to Wolfgang;
3628
3629	return 0;
3630}
3631
3632void no_more_time (int sig)
3633{
3634      hire_a_guru();
3635}
3636
3637
3638Coding Standards:
3639-----------------
3640
3641All contributions to U-Boot should conform to the Linux kernel
3642coding style; see the file "Documentation/CodingStyle" and the script
3643"scripts/Lindent" in your Linux kernel source directory.  In sources
3644originating from U-Boot a style corresponding to "Lindent -pcs" (adding
3645spaces before parameters to function calls) is actually used.
3646
3647Source files originating from a different project (for example the
3648MTD subsystem) are generally exempt from these guidelines and are not
3649reformated to ease subsequent migration to newer versions of those
3650sources.
3651
3652Please note that U-Boot is implemented in C (and to some small parts in
3653Assembler); no C++ is used, so please do not use C++ style comments (//)
3654in your code.
3655
3656Please also stick to the following formatting rules:
3657- remove any trailing white space
3658- use TAB characters for indentation, not spaces
3659- make sure NOT to use DOS '\r\n' line feeds
3660- do not add more than 2 empty lines to source files
3661- do not add trailing empty lines to source files
3662
3663Submissions which do not conform to the standards may be returned
3664with a request to reformat the changes.
3665
3666
3667Submitting Patches:
3668-------------------
3669
3670Since the number of patches for U-Boot is growing, we need to
3671establish some rules. Submissions which do not conform to these rules
3672may be rejected, even when they contain important and valuable stuff.
3673
3674Patches shall be sent to the u-boot-users mailing list.
3675
3676When you send a patch, please include the following information with
3677it:
3678
3679* For bug fixes: a description of the bug and how your patch fixes
3680  this bug. Please try to include a way of demonstrating that the
3681  patch actually fixes something.
3682
3683* For new features: a description of the feature and your
3684  implementation.
3685
3686* A CHANGELOG entry as plaintext (separate from the patch)
3687
3688* For major contributions, your entry to the CREDITS file
3689
3690* When you add support for a new board, don't forget to add this
3691  board to the MAKEALL script, too.
3692
3693* If your patch adds new configuration options, don't forget to
3694  document these in the README file.
3695
3696* The patch itself. If you are accessing the CVS repository use "cvs
3697  update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
3698  version of diff does not support these options, then get the latest
3699  version of GNU diff.
3700
3701  The current directory when running this command shall be the top
3702  level directory of the U-Boot source tree, or it's parent directory
3703  (i. e. please make sure that your patch includes sufficient
3704  directory information for the affected files).
3705
3706  We accept patches as plain text, MIME attachments or as uuencoded
3707  gzipped text.
3708
3709* If one logical set of modifications affects or creates several
3710  files, all these changes shall be submitted in a SINGLE patch file.
3711
3712* Changesets that contain different, unrelated modifications shall be
3713  submitted as SEPARATE patches, one patch per changeset.
3714
3715
3716Notes:
3717
3718* Before sending the patch, run the MAKEALL script on your patched
3719  source tree and make sure that no errors or warnings are reported
3720  for any of the boards.
3721
3722* Keep your modifications to the necessary minimum: A patch
3723  containing several unrelated changes or arbitrary reformats will be
3724  returned with a request to re-formatting / split it.
3725
3726* If you modify existing code, make sure that your new code does not
3727  add to the memory footprint of the code ;-) Small is beautiful!
3728  When adding new features, these should compile conditionally only
3729  (using #ifdef), and the resulting code with the new feature
3730  disabled must not need more memory than the old code without your
3731  modification.
3732
3733* Remember that there is a size limit of 40 kB per message on the
3734  u-boot-users mailing list. Compression may help.
3735