xref: /rk3399_rockchip-uboot/README (revision fc43be478f2aa37ce38acd85355038866e4162af)
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- libfdt 	Library files to support flattened device trees
168- net		Networking code
169- post		Power On Self Test
170- rtc		Real Time Clock drivers
171- tools		Tools to build S-Record or U-Boot images, etc.
172
173Software Configuration:
174=======================
175
176Configuration is usually done using C preprocessor defines; the
177rationale behind that is to avoid dead code whenever possible.
178
179There are two classes of configuration variables:
180
181* Configuration _OPTIONS_:
182  These are selectable by the user and have names beginning with
183  "CONFIG_".
184
185* Configuration _SETTINGS_:
186  These depend on the hardware etc. and should not be meddled with if
187  you don't know what you're doing; they have names beginning with
188  "CFG_".
189
190Later we will add a configuration tool - probably similar to or even
191identical to what's used for the Linux kernel. Right now, we have to
192do the configuration by hand, which means creating some symbolic
193links and editing some configuration files. We use the TQM8xxL boards
194as an example here.
195
196
197Selection of Processor Architecture and Board Type:
198---------------------------------------------------
199
200For all supported boards there are ready-to-use default
201configurations available; just type "make <board_name>_config".
202
203Example: For a TQM823L module type:
204
205	cd u-boot
206	make TQM823L_config
207
208For the Cogent platform, you need to specify the cpu type as well;
209e.g. "make cogent_mpc8xx_config". And also configure the cogent
210directory according to the instructions in cogent/README.
211
212
213Configuration Options:
214----------------------
215
216Configuration depends on the combination of board and CPU type; all
217such information is kept in a configuration file
218"include/configs/<board_name>.h".
219
220Example: For a TQM823L module, all configuration settings are in
221"include/configs/TQM823L.h".
222
223
224Many of the options are named exactly as the corresponding Linux
225kernel configuration options. The intention is to make it easier to
226build a config tool - later.
227
228
229The following options need to be configured:
230
231- CPU Type:	Define exactly one of
232
233		PowerPC based CPUs:
234		-------------------
235		CONFIG_MPC823,	CONFIG_MPC850,	CONFIG_MPC855,	CONFIG_MPC860
236	or	CONFIG_MPC5xx
237	or	CONFIG_MPC8220
238	or	CONFIG_MPC824X, CONFIG_MPC8260
239	or	CONFIG_MPC85xx
240	or	CONFIG_IOP480
241	or	CONFIG_405GP
242	or	CONFIG_405EP
243	or	CONFIG_440
244	or	CONFIG_MPC74xx
245	or	CONFIG_750FX
246
247		ARM based CPUs:
248		---------------
249		CONFIG_SA1110
250		CONFIG_ARM7
251		CONFIG_PXA250
252		CONFIG_PXA27X
253		CONFIG_CPU_MONAHANS
254
255		MicroBlaze based CPUs:
256		----------------------
257		CONFIG_MICROBLAZE
258
259		Nios-2 based CPUs:
260		----------------------
261		CONFIG_NIOS2
262
263		AVR32 based CPUs:
264		----------------------
265		CONFIG_AT32AP
266
267- Board Type:	Define exactly one of
268
269		PowerPC based boards:
270		---------------------
271
272		CONFIG_ADCIOP		CONFIG_FPS860L		CONFIG_OXC
273		CONFIG_ADS860		CONFIG_GEN860T		CONFIG_PCI405
274		CONFIG_AMX860		CONFIG_GENIETV		CONFIG_PCIPPC2
275		CONFIG_AP1000		CONFIG_GTH		CONFIG_PCIPPC6
276		CONFIG_AR405		CONFIG_gw8260		CONFIG_pcu_e
277		CONFIG_BAB7xx		CONFIG_hermes		CONFIG_PIP405
278		CONFIG_BC3450		CONFIG_hymod		CONFIG_PM826
279		CONFIG_c2mon		CONFIG_IAD210		CONFIG_ppmc8260
280		CONFIG_CANBT		CONFIG_ICU862		CONFIG_QS823
281		CONFIG_CCM		CONFIG_IP860		CONFIG_QS850
282		CONFIG_CMI		CONFIG_IPHASE4539	CONFIG_QS860T
283		CONFIG_cogent_mpc8260	CONFIG_IVML24		CONFIG_RBC823
284		CONFIG_cogent_mpc8xx	CONFIG_IVML24_128	CONFIG_RPXClassic
285		CONFIG_CPCI405		CONFIG_IVML24_256	CONFIG_RPXlite
286		CONFIG_CPCI4052		CONFIG_IVMS8		CONFIG_RPXsuper
287		CONFIG_CPCIISER4	CONFIG_IVMS8_128	CONFIG_rsdproto
288		CONFIG_CPU86		CONFIG_IVMS8_256	CONFIG_sacsng
289		CONFIG_CRAYL1		CONFIG_JSE		CONFIG_Sandpoint8240
290		CONFIG_CSB272		CONFIG_LANTEC		CONFIG_Sandpoint8245
291		CONFIG_CU824		CONFIG_LITE5200B	CONFIG_sbc8260
292		CONFIG_DASA_SIM		CONFIG_lwmon		CONFIG_sbc8560
293		CONFIG_DB64360		CONFIG_MBX		CONFIG_SM850
294		CONFIG_DB64460		CONFIG_MBX860T		CONFIG_SPD823TS
295		CONFIG_DU405		CONFIG_MHPC		CONFIG_STXGP3
296		CONFIG_DUET_ADS		CONFIG_MIP405		CONFIG_SXNI855T
297		CONFIG_EBONY		CONFIG_MOUSSE		CONFIG_TQM823L
298		CONFIG_ELPPC		CONFIG_MPC8260ADS	CONFIG_TQM8260
299		CONFIG_ELPT860		CONFIG_MPC8540ADS	CONFIG_TQM850L
300		CONFIG_ep8260		CONFIG_MPC8540EVAL	CONFIG_TQM855L
301		CONFIG_ERIC		CONFIG_MPC8560ADS	CONFIG_TQM860L
302		CONFIG_ESTEEM192E	CONFIG_MUSENKI		CONFIG_TTTech
303		CONFIG_ETX094		CONFIG_MVS1		CONFIG_UTX8245
304		CONFIG_EVB64260		CONFIG_NETPHONE		CONFIG_V37
305		CONFIG_FADS823		CONFIG_NETTA		CONFIG_W7OLMC
306		CONFIG_FADS850SAR	CONFIG_NETVIA		CONFIG_W7OLMG
307		CONFIG_FADS860T		CONFIG_NX823		CONFIG_WALNUT
308		CONFIG_FLAGADM		CONFIG_OCRTC		CONFIG_ZPC1900
309		CONFIG_FPS850L		CONFIG_ORSG		CONFIG_ZUMA
310
311		ARM based boards:
312		-----------------
313
314		CONFIG_ARMADILLO,	CONFIG_AT91RM9200DK,	CONFIG_CERF250,
315		CONFIG_CSB637,		CONFIG_DELTA,		CONFIG_DNP1110,
316		CONFIG_EP7312,		CONFIG_H2_OMAP1610,	CONFIG_HHP_CRADLE,
317		CONFIG_IMPA7,	    CONFIG_INNOVATOROMAP1510,	CONFIG_INNOVATOROMAP1610,
318		CONFIG_KB9202,		CONFIG_LART,		CONFIG_LPD7A400,
319		CONFIG_LUBBOCK,		CONFIG_OSK_OMAP5912,	CONFIG_OMAP2420H4,
320		CONFIG_PLEB2,		CONFIG_SHANNON,		CONFIG_P2_OMAP730,
321		CONFIG_SMDK2400,	CONFIG_SMDK2410,	CONFIG_TRAB,
322		CONFIG_VCMA9
323
324		MicroBlaze based boards:
325		------------------------
326
327		CONFIG_SUZAKU
328
329		Nios-2 based boards:
330		------------------------
331
332		CONFIG_PCI5441 CONFIG_PK1C20
333		CONFIG_EP1C20 CONFIG_EP1S10 CONFIG_EP1S40
334
335		AVR32 based boards:
336		-------------------
337
338		CONFIG_ATSTK1000
339
340- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
341		Define exactly one of
342		CONFIG_ATSTK1002
343
344
345- CPU Module Type: (if CONFIG_COGENT is defined)
346		Define exactly one of
347		CONFIG_CMA286_60_OLD
348--- FIXME --- not tested yet:
349		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
350		CONFIG_CMA287_23, CONFIG_CMA287_50
351
352- Motherboard Type: (if CONFIG_COGENT is defined)
353		Define exactly one of
354		CONFIG_CMA101, CONFIG_CMA102
355
356- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
357		Define one or more of
358		CONFIG_CMA302
359
360- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
361		Define one or more of
362		CONFIG_LCD_HEARTBEAT	- update a character position on
363					  the lcd display every second with
364					  a "rotator" |\-/|\-/
365
366- Board flavour: (if CONFIG_MPC8260ADS is defined)
367		CONFIG_ADSTYPE
368		Possible values are:
369			CFG_8260ADS	- original MPC8260ADS
370			CFG_8266ADS	- MPC8266ADS
371			CFG_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
372			CFG_8272ADS	- MPC8272ADS
373
374- MPC824X Family Member (if CONFIG_MPC824X is defined)
375		Define exactly one of
376		CONFIG_MPC8240, CONFIG_MPC8245
377
378- 8xx CPU Options: (if using an MPC8xx cpu)
379		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
380					  get_gclk_freq() cannot work
381					  e.g. if there is no 32KHz
382					  reference PIT/RTC clock
383		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
384					  or XTAL/EXTAL)
385
386- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
387		CFG_8xx_CPUCLK_MIN
388		CFG_8xx_CPUCLK_MAX
389		CONFIG_8xx_CPUCLK_DEFAULT
390			See doc/README.MPC866
391
392		CFG_MEASURE_CPUCLK
393
394		Define this to measure the actual CPU clock instead
395		of relying on the correctness of the configured
396		values. Mostly useful for board bringup to make sure
397		the PLL is locked at the intended frequency. Note
398		that this requires a (stable) reference clock (32 kHz
399		RTC clock or CFG_8XX_XIN)
400
401- Intel Monahans options:
402		CFG_MONAHANS_RUN_MODE_OSC_RATIO
403
404		Defines the Monahans run mode to oscillator
405		ratio. Valid values are 8, 16, 24, 31. The core
406		frequency is this value multiplied by 13 MHz.
407
408		CFG_MONAHANS_TURBO_RUN_MODE_RATIO
409
410		Defines the Monahans turbo mode to oscillator
411		ratio. Valid values are 1 (default if undefined) and
412		2. The core frequency as calculated above is multiplied
413		by this value.
414
415- Linux Kernel Interface:
416		CONFIG_CLOCKS_IN_MHZ
417
418		U-Boot stores all clock information in Hz
419		internally. For binary compatibility with older Linux
420		kernels (which expect the clocks passed in the
421		bd_info data to be in MHz) the environment variable
422		"clocks_in_mhz" can be defined so that U-Boot
423		converts clock data to MHZ before passing it to the
424		Linux kernel.
425		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
426		"clocks_in_mhz=1" is  automatically  included  in  the
427		default environment.
428
429		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
430
431		When transfering memsize parameter to linux, some versions
432		expect it to be in bytes, others in MB.
433		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
434
435		CONFIG_OF_LIBFDT / CONFIG_OF_FLAT_TREE
436
437		New kernel versions are expecting firmware settings to be
438		passed using flattened device trees (based on open firmware
439		concepts).
440
441		CONFIG_OF_LIBFDT
442		 * New libfdt-based support
443		 * Adds the "fdt" command
444		 * The bootm command does _not_ modify the fdt
445
446		CONFIG_OF_FLAT_TREE
447		 * Deprecated, see CONFIG_OF_LIBFDT
448		 * Original ft_build.c-based support
449		 * Automatically modifies the dft as part of the bootm command
450		 * The environment variable "disable_of", when set,
451		     disables this functionality.
452
453		CONFIG_OF_FLAT_TREE_MAX_SIZE
454
455		The maximum size of the constructed OF tree.
456
457		OF_CPU - The proper name of the cpus node.
458		OF_SOC - The proper name of the soc node.
459		OF_TBCLK - The timebase frequency.
460		OF_STDOUT_PATH - The path to the console device
461
462		CONFIG_OF_HAS_BD_T
463
464		 * CONFIG_OF_LIBFDT - enables the "fdt bd_t" command
465		 * CONFIG_OF_FLAT_TREE - The resulting flat device tree
466		     will have a copy of the bd_t.  Space should be
467		     pre-allocated in the dts for the bd_t.
468
469		CONFIG_OF_HAS_UBOOT_ENV
470
471		 * CONFIG_OF_LIBFDT - enables the "fdt bd_t" command
472		 * CONFIG_OF_FLAT_TREE - The resulting flat device tree
473		     will have a copy of u-boot's environment variables
474
475		CONFIG_OF_BOARD_SETUP
476
477		Board code has addition modification that it wants to make
478		to the flat device tree before handing it off to the kernel
479
480		CONFIG_OF_BOOT_CPU
481
482		This define fills in the correct boot cpu in the boot
483		param header, the default value is zero if undefined.
484
485- Serial Ports:
486		CFG_PL010_SERIAL
487
488		Define this if you want support for Amba PrimeCell PL010 UARTs.
489
490		CFG_PL011_SERIAL
491
492		Define this if you want support for Amba PrimeCell PL011 UARTs.
493
494		CONFIG_PL011_CLOCK
495
496		If you have Amba PrimeCell PL011 UARTs, set this variable to
497		the clock speed of the UARTs.
498
499		CONFIG_PL01x_PORTS
500
501		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
502		define this to a list of base addresses for each (supported)
503		port. See e.g. include/configs/versatile.h
504
505
506- Console Interface:
507		Depending on board, define exactly one serial port
508		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
509		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
510		console by defining CONFIG_8xx_CONS_NONE
511
512		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
513		port routines must be defined elsewhere
514		(i.e. serial_init(), serial_getc(), ...)
515
516		CONFIG_CFB_CONSOLE
517		Enables console device for a color framebuffer. Needs following
518		defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
519			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
520						(default big endian)
521			VIDEO_HW_RECTFILL	graphic chip supports
522						rectangle fill
523						(cf. smiLynxEM)
524			VIDEO_HW_BITBLT		graphic chip supports
525						bit-blit (cf. smiLynxEM)
526			VIDEO_VISIBLE_COLS	visible pixel columns
527						(cols=pitch)
528			VIDEO_VISIBLE_ROWS	visible pixel rows
529			VIDEO_PIXEL_SIZE	bytes per pixel
530			VIDEO_DATA_FORMAT	graphic data format
531						(0-5, cf. cfb_console.c)
532			VIDEO_FB_ADRS		framebuffer address
533			VIDEO_KBD_INIT_FCT	keyboard int fct
534						(i.e. i8042_kbd_init())
535			VIDEO_TSTC_FCT		test char fct
536						(i.e. i8042_tstc)
537			VIDEO_GETC_FCT		get char fct
538						(i.e. i8042_getc)
539			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
540						(requires blink timer
541						cf. i8042.c)
542			CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
543			CONFIG_CONSOLE_TIME	display time/date info in
544						upper right corner
545						(requires CFG_CMD_DATE)
546			CONFIG_VIDEO_LOGO	display Linux logo in
547						upper left corner
548			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
549						linux_logo.h for logo.
550						Requires CONFIG_VIDEO_LOGO
551			CONFIG_CONSOLE_EXTRA_INFO
552						addional board info beside
553						the logo
554
555		When CONFIG_CFB_CONSOLE is defined, video console is
556		default i/o. Serial console can be forced with
557		environment 'console=serial'.
558
559		When CONFIG_SILENT_CONSOLE is defined, all console
560		messages (by U-Boot and Linux!) can be silenced with
561		the "silent" environment variable. See
562		doc/README.silent for more information.
563
564- Console Baudrate:
565		CONFIG_BAUDRATE - in bps
566		Select one of the baudrates listed in
567		CFG_BAUDRATE_TABLE, see below.
568		CFG_BRGCLK_PRESCALE, baudrate prescale
569
570- Interrupt driven serial port input:
571		CONFIG_SERIAL_SOFTWARE_FIFO
572
573		PPC405GP only.
574		Use an interrupt handler for receiving data on the
575		serial port. It also enables using hardware handshake
576		(RTS/CTS) and UART's built-in FIFO. Set the number of
577		bytes the interrupt driven input buffer should have.
578
579		Leave undefined to disable this feature, including
580		disable the buffer and hardware handshake.
581
582- Console UART Number:
583		CONFIG_UART1_CONSOLE
584
585		AMCC PPC4xx only.
586		If defined internal UART1 (and not UART0) is used
587		as default U-Boot console.
588
589- Boot Delay:	CONFIG_BOOTDELAY - in seconds
590		Delay before automatically booting the default image;
591		set to -1 to disable autoboot.
592
593		See doc/README.autoboot for these options that
594		work with CONFIG_BOOTDELAY. None are required.
595		CONFIG_BOOT_RETRY_TIME
596		CONFIG_BOOT_RETRY_MIN
597		CONFIG_AUTOBOOT_KEYED
598		CONFIG_AUTOBOOT_PROMPT
599		CONFIG_AUTOBOOT_DELAY_STR
600		CONFIG_AUTOBOOT_STOP_STR
601		CONFIG_AUTOBOOT_DELAY_STR2
602		CONFIG_AUTOBOOT_STOP_STR2
603		CONFIG_ZERO_BOOTDELAY_CHECK
604		CONFIG_RESET_TO_RETRY
605
606- Autoboot Command:
607		CONFIG_BOOTCOMMAND
608		Only needed when CONFIG_BOOTDELAY is enabled;
609		define a command string that is automatically executed
610		when no character is read on the console interface
611		within "Boot Delay" after reset.
612
613		CONFIG_BOOTARGS
614		This can be used to pass arguments to the bootm
615		command. The value of CONFIG_BOOTARGS goes into the
616		environment value "bootargs".
617
618		CONFIG_RAMBOOT and CONFIG_NFSBOOT
619		The value of these goes into the environment as
620		"ramboot" and "nfsboot" respectively, and can be used
621		as a convenience, when switching between booting from
622		ram and nfs.
623
624- Pre-Boot Commands:
625		CONFIG_PREBOOT
626
627		When this option is #defined, the existence of the
628		environment variable "preboot" will be checked
629		immediately before starting the CONFIG_BOOTDELAY
630		countdown and/or running the auto-boot command resp.
631		entering interactive mode.
632
633		This feature is especially useful when "preboot" is
634		automatically generated or modified. For an example
635		see the LWMON board specific code: here "preboot" is
636		modified when the user holds down a certain
637		combination of keys on the (special) keyboard when
638		booting the systems
639
640- Serial Download Echo Mode:
641		CONFIG_LOADS_ECHO
642		If defined to 1, all characters received during a
643		serial download (using the "loads" command) are
644		echoed back. This might be needed by some terminal
645		emulations (like "cu"), but may as well just take
646		time on others. This setting #define's the initial
647		value of the "loads_echo" environment variable.
648
649- Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined)
650		CONFIG_KGDB_BAUDRATE
651		Select one of the baudrates listed in
652		CFG_BAUDRATE_TABLE, see below.
653
654- Monitor Functions:
655		CONFIG_COMMANDS
656		Most monitor functions can be selected (or
657		de-selected) by adjusting the definition of
658		CONFIG_COMMANDS; to select individual functions,
659		#define CONFIG_COMMANDS by "OR"ing any of the
660		following values:
661
662		#define enables commands:
663		-------------------------
664		CFG_CMD_ASKENV	* ask for env variable
665		CFG_CMD_AUTOSCRIPT Autoscript Support
666		CFG_CMD_BDI	  bdinfo
667		CFG_CMD_BEDBUG	* Include BedBug Debugger
668		CFG_CMD_BMP	* BMP support
669		CFG_CMD_BSP	* Board specific commands
670		CFG_CMD_BOOTD	  bootd
671		CFG_CMD_CACHE	* icache, dcache
672		CFG_CMD_CONSOLE	  coninfo
673		CFG_CMD_DATE	* support for RTC, date/time...
674		CFG_CMD_DHCP	* DHCP support
675		CFG_CMD_DIAG	* Diagnostics
676		CFG_CMD_DOC	* Disk-On-Chip Support
677		CFG_CMD_DTT	* Digital Therm and Thermostat
678		CFG_CMD_ECHO	  echo arguments
679		CFG_CMD_EEPROM	* EEPROM read/write support
680		CFG_CMD_ELF	* bootelf, bootvx
681		CFG_CMD_ENV	  saveenv
682		CFG_CMD_FDC	* Floppy Disk Support
683		CFG_CMD_FAT	* FAT partition support
684		CFG_CMD_FDOS	* Dos diskette Support
685		CFG_CMD_FLASH	  flinfo, erase, protect
686		CFG_CMD_FPGA	  FPGA device initialization support
687		CFG_CMD_HWFLOW	* RTS/CTS hw flow control
688		CFG_CMD_I2C	* I2C serial bus support
689		CFG_CMD_IDE	* IDE harddisk support
690		CFG_CMD_IMI	  iminfo
691		CFG_CMD_IMLS	  List all found images
692		CFG_CMD_IMMAP	* IMMR dump support
693		CFG_CMD_IRQ	* irqinfo
694		CFG_CMD_ITEST	  Integer/string test of 2 values
695		CFG_CMD_JFFS2	* JFFS2 Support
696		CFG_CMD_KGDB	* kgdb
697		CFG_CMD_LOADB	  loadb
698		CFG_CMD_LOADS	  loads
699		CFG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
700				  loop, loopw, mtest
701		CFG_CMD_MISC	  Misc functions like sleep etc
702		CFG_CMD_MMC	* MMC memory mapped support
703		CFG_CMD_MII	* MII utility commands
704		CFG_CMD_NAND	* NAND support
705		CFG_CMD_NET	  bootp, tftpboot, rarpboot
706		CFG_CMD_PCI	* pciinfo
707		CFG_CMD_PCMCIA	* PCMCIA support
708		CFG_CMD_PING	* send ICMP ECHO_REQUEST to network host
709		CFG_CMD_PORTIO	* Port I/O
710		CFG_CMD_REGINFO * Register dump
711		CFG_CMD_RUN	  run command in env variable
712		CFG_CMD_SAVES	* save S record dump
713		CFG_CMD_SCSI	* SCSI Support
714		CFG_CMD_SDRAM	* print SDRAM configuration information
715				  (requires CFG_CMD_I2C)
716		CFG_CMD_SETGETDCR Support for DCR Register access (4xx only)
717		CFG_CMD_SPI	* SPI serial bus support
718		CFG_CMD_USB	* USB support
719		CFG_CMD_VFD	* VFD support (TRAB)
720		CFG_CMD_BSP	* Board SPecific functions
721		CFG_CMD_CDP	* Cisco Discover Protocol support
722		CFG_CMD_FSL	* Microblaze FSL support
723		-----------------------------------------------
724		CFG_CMD_ALL	all
725
726		CONFIG_CMD_DFL	Default configuration; at the moment
727				this is includes all commands, except
728				the ones marked with "*" in the list
729				above.
730
731		If you don't define CONFIG_COMMANDS it defaults to
732		CONFIG_CMD_DFL in include/cmd_confdefs.h. A board can
733		override the default settings in the respective
734		include file.
735
736		EXAMPLE: If you want all functions except of network
737		support you can write:
738
739		#define CONFIG_COMMANDS (CFG_CMD_ALL & ~CFG_CMD_NET)
740
741	Other Commands:
742		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
743
744	Note:	Don't enable the "icache" and "dcache" commands
745		(configuration option CFG_CMD_CACHE) unless you know
746		what you (and your U-Boot users) are doing. Data
747		cache cannot be enabled on systems like the 8xx or
748		8260 (where accesses to the IMMR region must be
749		uncached), and it cannot be disabled on all other
750		systems where we (mis-) use the data cache to hold an
751		initial stack and some data.
752
753
754		XXX - this list needs to get updated!
755
756- Watchdog:
757		CONFIG_WATCHDOG
758		If this variable is defined, it enables watchdog
759		support. There must be support in the platform specific
760		code for a watchdog. For the 8xx and 8260 CPUs, the
761		SIU Watchdog feature is enabled in the SYPCR
762		register.
763
764- U-Boot Version:
765		CONFIG_VERSION_VARIABLE
766		If this variable is defined, an environment variable
767		named "ver" is created by U-Boot showing the U-Boot
768		version as printed by the "version" command.
769		This variable is readonly.
770
771- Real-Time Clock:
772
773		When CFG_CMD_DATE is selected, the type of the RTC
774		has to be selected, too. Define exactly one of the
775		following options:
776
777		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
778		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
779		CONFIG_RTC_MC146818	- use MC146818 RTC
780		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
781		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
782		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
783		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
784		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
785
786		Note that if the RTC uses I2C, then the I2C interface
787		must also be configured. See I2C Support, below.
788
789- Timestamp Support:
790
791		When CONFIG_TIMESTAMP is selected, the timestamp
792		(date and time) of an image is printed by image
793		commands like bootm or iminfo. This option is
794		automatically enabled when you select CFG_CMD_DATE .
795
796- Partition Support:
797		CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
798		and/or CONFIG_ISO_PARTITION
799
800		If IDE or SCSI support	is  enabled  (CFG_CMD_IDE  or
801		CFG_CMD_SCSI) you must configure support for at least
802		one partition type as well.
803
804- IDE Reset method:
805		CONFIG_IDE_RESET_ROUTINE - this is defined in several
806		board configurations files but used nowhere!
807
808		CONFIG_IDE_RESET - is this is defined, IDE Reset will
809		be performed by calling the function
810			ide_set_reset(int reset)
811		which has to be defined in a board specific file
812
813- ATAPI Support:
814		CONFIG_ATAPI
815
816		Set this to enable ATAPI support.
817
818- LBA48 Support
819		CONFIG_LBA48
820
821		Set this to enable support for disks larger than 137GB
822		Also look at CFG_64BIT_LBA ,CFG_64BIT_VSPRINTF and CFG_64BIT_STRTOUL
823		Whithout these , LBA48 support uses 32bit variables and will 'only'
824		support disks up to 2.1TB.
825
826		CFG_64BIT_LBA:
827			When enabled, makes the IDE subsystem use 64bit sector addresses.
828			Default is 32bit.
829
830- SCSI Support:
831		At the moment only there is only support for the
832		SYM53C8XX SCSI controller; define
833		CONFIG_SCSI_SYM53C8XX to enable it.
834
835		CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
836		CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
837		CFG_SCSI_MAX_LUN] can be adjusted to define the
838		maximum numbers of LUNs, SCSI ID's and target
839		devices.
840		CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
841
842- NETWORK Support (PCI):
843		CONFIG_E1000
844		Support for Intel 8254x gigabit chips.
845
846		CONFIG_EEPRO100
847		Support for Intel 82557/82559/82559ER chips.
848		Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom
849		write routine for first time initialisation.
850
851		CONFIG_TULIP
852		Support for Digital 2114x chips.
853		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
854		modem chip initialisation (KS8761/QS6611).
855
856		CONFIG_NATSEMI
857		Support for National dp83815 chips.
858
859		CONFIG_NS8382X
860		Support for National dp8382[01] gigabit chips.
861
862- NETWORK Support (other):
863
864		CONFIG_DRIVER_LAN91C96
865		Support for SMSC's LAN91C96 chips.
866
867			CONFIG_LAN91C96_BASE
868			Define this to hold the physical address
869			of the LAN91C96's I/O space
870
871			CONFIG_LAN91C96_USE_32_BIT
872			Define this to enable 32 bit addressing
873
874		CONFIG_DRIVER_SMC91111
875		Support for SMSC's LAN91C111 chip
876
877			CONFIG_SMC91111_BASE
878			Define this to hold the physical address
879			of the device (I/O space)
880
881			CONFIG_SMC_USE_32_BIT
882			Define this if data bus is 32 bits
883
884			CONFIG_SMC_USE_IOFUNCS
885			Define this to use i/o functions instead of macros
886			(some hardware wont work with macros)
887
888- USB Support:
889		At the moment only the UHCI host controller is
890		supported (PIP405, MIP405, MPC5200); define
891		CONFIG_USB_UHCI to enable it.
892		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
893		and define CONFIG_USB_STORAGE to enable the USB
894		storage devices.
895		Note:
896		Supported are USB Keyboards and USB Floppy drives
897		(TEAC FD-05PUB).
898		MPC5200 USB requires additional defines:
899			CONFIG_USB_CLOCK
900				for 528 MHz Clock: 0x0001bbbb
901			CONFIG_USB_CONFIG
902				for differential drivers: 0x00001000
903				for single ended drivers: 0x00005000
904			CFG_USB_EVENT_POLL
905				May be defined to allow interrupt polling
906				instead of using asynchronous interrupts
907
908- USB Device:
909		Define the below if you wish to use the USB console.
910		Once firmware is rebuilt from a serial console issue the
911		command "setenv stdin usbtty; setenv stdout usbtty" and
912		attach your usb cable. The Unix command "dmesg" should print
913		it has found a new device. The environment variable usbtty
914		can be set to gserial or cdc_acm to enable your device to
915		appear to a USB host as a Linux gserial device or a
916		Common Device Class Abstract Control Model serial device.
917		If you select usbtty = gserial you should be able to enumerate
918		a Linux host by
919		# modprobe usbserial vendor=0xVendorID product=0xProductID
920		else if using cdc_acm, simply setting the environment
921		variable usbtty to be cdc_acm should suffice. The following
922		might be defined in YourBoardName.h
923
924			CONFIG_USB_DEVICE
925			Define this to build a UDC device
926
927			CONFIG_USB_TTY
928			Define this to have a tty type of device available to
929			talk to the UDC device
930
931			CFG_CONSOLE_IS_IN_ENV
932			Define this if you want stdin, stdout &/or stderr to
933			be set to usbtty.
934
935			mpc8xx:
936				CFG_USB_EXTC_CLK 0xBLAH
937				Derive USB clock from external clock "blah"
938				- CFG_USB_EXTC_CLK 0x02
939
940				CFG_USB_BRG_CLK 0xBLAH
941				Derive USB clock from brgclk
942				- CFG_USB_BRG_CLK 0x04
943
944		If you have a USB-IF assigned VendorID then you may wish to
945		define your own vendor specific values either in BoardName.h
946		or directly in usbd_vendor_info.h. If you don't define
947		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
948		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
949		should pretend to be a Linux device to it's target host.
950
951			CONFIG_USBD_MANUFACTURER
952			Define this string as the name of your company for
953			- CONFIG_USBD_MANUFACTURER "my company"
954
955			CONFIG_USBD_PRODUCT_NAME
956			Define this string as the name of your product
957			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
958
959			CONFIG_USBD_VENDORID
960			Define this as your assigned Vendor ID from the USB
961			Implementors Forum. This *must* be a genuine Vendor ID
962			to avoid polluting the USB namespace.
963			- CONFIG_USBD_VENDORID 0xFFFF
964
965			CONFIG_USBD_PRODUCTID
966			Define this as the unique Product ID
967			for your device
968			- CONFIG_USBD_PRODUCTID 0xFFFF
969
970
971- MMC Support:
972		The MMC controller on the Intel PXA is supported. To
973		enable this define CONFIG_MMC. The MMC can be
974		accessed from the boot prompt by mapping the device
975		to physical memory similar to flash. Command line is
976		enabled with CFG_CMD_MMC. The MMC driver also works with
977		the FAT fs. This is enabled with CFG_CMD_FAT.
978
979- Journaling Flash filesystem support:
980		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
981		CONFIG_JFFS2_NAND_DEV
982		Define these for a default partition on a NAND device
983
984		CFG_JFFS2_FIRST_SECTOR,
985		CFG_JFFS2_FIRST_BANK, CFG_JFFS2_NUM_BANKS
986		Define these for a default partition on a NOR device
987
988		CFG_JFFS_CUSTOM_PART
989		Define this to create an own partition. You have to provide a
990		function struct part_info* jffs2_part_info(int part_num)
991
992		If you define only one JFFS2 partition you may also want to
993		#define CFG_JFFS_SINGLE_PART	1
994		to disable the command chpart. This is the default when you
995		have not defined a custom partition
996
997- Keyboard Support:
998		CONFIG_ISA_KEYBOARD
999
1000		Define this to enable standard (PC-Style) keyboard
1001		support
1002
1003		CONFIG_I8042_KBD
1004		Standard PC keyboard driver with US (is default) and
1005		GERMAN key layout (switch via environment 'keymap=de') support.
1006		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1007		for cfb_console. Supports cursor blinking.
1008
1009- Video support:
1010		CONFIG_VIDEO
1011
1012		Define this to enable video support (for output to
1013		video).
1014
1015		CONFIG_VIDEO_CT69000
1016
1017		Enable Chips & Technologies 69000 Video chip
1018
1019		CONFIG_VIDEO_SMI_LYNXEM
1020		Enable Silicon Motion SMI 712/710/810 Video chip. The
1021		video output is selected via environment 'videoout'
1022		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1023		assumed.
1024
1025		For the CT69000 and SMI_LYNXEM drivers, videomode is
1026		selected via environment 'videomode'. Two diferent ways
1027		are possible:
1028		- "videomode=num"   'num' is a standard LiLo mode numbers.
1029		Following standard modes are supported	(* is default):
1030
1031		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1032		-------------+---------------------------------------------
1033		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1034		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1035		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1036		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1037		-------------+---------------------------------------------
1038		(i.e. setenv videomode 317; saveenv; reset;)
1039
1040		- "videomode=bootargs" all the video parameters are parsed
1041		from the bootargs. (See drivers/videomodes.c)
1042
1043
1044		CONFIG_VIDEO_SED13806
1045		Enable Epson SED13806 driver. This driver supports 8bpp
1046		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1047		or CONFIG_VIDEO_SED13806_16BPP
1048
1049- Keyboard Support:
1050		CONFIG_KEYBOARD
1051
1052		Define this to enable a custom keyboard support.
1053		This simply calls drv_keyboard_init() which must be
1054		defined in your board-specific files.
1055		The only board using this so far is RBC823.
1056
1057- LCD Support:	CONFIG_LCD
1058
1059		Define this to enable LCD support (for output to LCD
1060		display); also select one of the supported displays
1061		by defining one of these:
1062
1063		CONFIG_NEC_NL6448AC33:
1064
1065			NEC NL6448AC33-18. Active, color, single scan.
1066
1067		CONFIG_NEC_NL6448BC20
1068
1069			NEC NL6448BC20-08. 6.5", 640x480.
1070			Active, color, single scan.
1071
1072		CONFIG_NEC_NL6448BC33_54
1073
1074			NEC NL6448BC33-54. 10.4", 640x480.
1075			Active, color, single scan.
1076
1077		CONFIG_SHARP_16x9
1078
1079			Sharp 320x240. Active, color, single scan.
1080			It isn't 16x9, and I am not sure what it is.
1081
1082		CONFIG_SHARP_LQ64D341
1083
1084			Sharp LQ64D341 display, 640x480.
1085			Active, color, single scan.
1086
1087		CONFIG_HLD1045
1088
1089			HLD1045 display, 640x480.
1090			Active, color, single scan.
1091
1092		CONFIG_OPTREX_BW
1093
1094			Optrex	 CBL50840-2 NF-FW 99 22 M5
1095			or
1096			Hitachi	 LMG6912RPFC-00T
1097			or
1098			Hitachi	 SP14Q002
1099
1100			320x240. Black & white.
1101
1102		Normally display is black on white background; define
1103		CFG_WHITE_ON_BLACK to get it inverted.
1104
1105- Splash Screen Support: CONFIG_SPLASH_SCREEN
1106
1107		If this option is set, the environment is checked for
1108		a variable "splashimage". If found, the usual display
1109		of logo, copyright and system information on the LCD
1110		is suppressed and the BMP image at the address
1111		specified in "splashimage" is loaded instead. The
1112		console is redirected to the "nulldev", too. This
1113		allows for a "silent" boot where a splash screen is
1114		loaded very quickly after power-on.
1115
1116- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1117
1118		If this option is set, additionally to standard BMP
1119		images, gzipped BMP images can be displayed via the
1120		splashscreen support or the bmp command.
1121
1122- Compression support:
1123		CONFIG_BZIP2
1124
1125		If this option is set, support for bzip2 compressed
1126		images is included. If not, only uncompressed and gzip
1127		compressed images are supported.
1128
1129		NOTE: the bzip2 algorithm requires a lot of RAM, so
1130		the malloc area (as defined by CFG_MALLOC_LEN) should
1131		be at least 4MB.
1132
1133- MII/PHY support:
1134		CONFIG_PHY_ADDR
1135
1136		The address of PHY on MII bus.
1137
1138		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1139
1140		The clock frequency of the MII bus
1141
1142		CONFIG_PHY_GIGE
1143
1144		If this option is set, support for speed/duplex
1145		detection of Gigabit PHY is included.
1146
1147		CONFIG_PHY_RESET_DELAY
1148
1149		Some PHY like Intel LXT971A need extra delay after
1150		reset before any MII register access is possible.
1151		For such PHY, set this option to the usec delay
1152		required. (minimum 300usec for LXT971A)
1153
1154		CONFIG_PHY_CMD_DELAY (ppc4xx)
1155
1156		Some PHY like Intel LXT971A need extra delay after
1157		command issued before MII status register can be read
1158
1159- Ethernet address:
1160		CONFIG_ETHADDR
1161		CONFIG_ETH2ADDR
1162		CONFIG_ETH3ADDR
1163
1164		Define a default value for ethernet address to use
1165		for the respective ethernet interface, in case this
1166		is not determined automatically.
1167
1168- IP address:
1169		CONFIG_IPADDR
1170
1171		Define a default value for the IP address to use for
1172		the default ethernet interface, in case this is not
1173		determined through e.g. bootp.
1174
1175- Server IP address:
1176		CONFIG_SERVERIP
1177
1178		Defines a default value for theIP address of a TFTP
1179		server to contact when using the "tftboot" command.
1180
1181- BOOTP Recovery Mode:
1182		CONFIG_BOOTP_RANDOM_DELAY
1183
1184		If you have many targets in a network that try to
1185		boot using BOOTP, you may want to avoid that all
1186		systems send out BOOTP requests at precisely the same
1187		moment (which would happen for instance at recovery
1188		from a power failure, when all systems will try to
1189		boot, thus flooding the BOOTP server. Defining
1190		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1191		inserted before sending out BOOTP requests. The
1192		following delays are insterted then:
1193
1194		1st BOOTP request:	delay 0 ... 1 sec
1195		2nd BOOTP request:	delay 0 ... 2 sec
1196		3rd BOOTP request:	delay 0 ... 4 sec
1197		4th and following
1198		BOOTP requests:		delay 0 ... 8 sec
1199
1200- DHCP Advanced Options:
1201		CONFIG_BOOTP_MASK
1202
1203		You can fine tune the DHCP functionality by adding
1204		these flags to the CONFIG_BOOTP_MASK define:
1205
1206		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1207		serverip from a DHCP server, it is possible that more
1208		than one DNS serverip is offered to the client.
1209		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1210		serverip will be stored in the additional environment
1211		variable "dnsip2". The first DNS serverip is always
1212		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1213		is added to the CONFIG_BOOTP_MASK.
1214
1215		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1216		to do a dynamic update of a DNS server. To do this, they
1217		need the hostname of the DHCP requester.
1218		If CONFIG_BOOP_SEND_HOSTNAME is added to the
1219		CONFIG_BOOTP_MASK, the content of the "hostname"
1220		environment variable is passed as option 12 to
1221		the DHCP server.
1222
1223 - CDP Options:
1224		CONFIG_CDP_DEVICE_ID
1225
1226		The device id used in CDP trigger frames.
1227
1228		CONFIG_CDP_DEVICE_ID_PREFIX
1229
1230		A two character string which is prefixed to the MAC address
1231		of the device.
1232
1233		CONFIG_CDP_PORT_ID
1234
1235		A printf format string which contains the ascii name of
1236		the port. Normally is set to "eth%d" which sets
1237		eth0 for the first ethernet, eth1 for the second etc.
1238
1239		CONFIG_CDP_CAPABILITIES
1240
1241		A 32bit integer which indicates the device capabilities;
1242		0x00000010 for a normal host which does not forwards.
1243
1244		CONFIG_CDP_VERSION
1245
1246		An ascii string containing the version of the software.
1247
1248		CONFIG_CDP_PLATFORM
1249
1250		An ascii string containing the name of the platform.
1251
1252		CONFIG_CDP_TRIGGER
1253
1254		A 32bit integer sent on the trigger.
1255
1256		CONFIG_CDP_POWER_CONSUMPTION
1257
1258		A 16bit integer containing the power consumption of the
1259		device in .1 of milliwatts.
1260
1261		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1262
1263		A byte containing the id of the VLAN.
1264
1265- Status LED:	CONFIG_STATUS_LED
1266
1267		Several configurations allow to display the current
1268		status using a LED. For instance, the LED will blink
1269		fast while running U-Boot code, stop blinking as
1270		soon as a reply to a BOOTP request was received, and
1271		start blinking slow once the Linux kernel is running
1272		(supported by a status LED driver in the Linux
1273		kernel). Defining CONFIG_STATUS_LED enables this
1274		feature in U-Boot.
1275
1276- CAN Support:	CONFIG_CAN_DRIVER
1277
1278		Defining CONFIG_CAN_DRIVER enables CAN driver support
1279		on those systems that support this (optional)
1280		feature, like the TQM8xxL modules.
1281
1282- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1283
1284		These enable I2C serial bus commands. Defining either of
1285		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1286		include the appropriate I2C driver for the selected cpu.
1287
1288		This will allow you to use i2c commands at the u-boot
1289		command line (as long as you set CFG_CMD_I2C in
1290		CONFIG_COMMANDS) and communicate with i2c based realtime
1291		clock chips. See common/cmd_i2c.c for a description of the
1292		command line interface.
1293
1294		CONFIG_I2C_CMD_TREE is a recommended option that places
1295		all I2C commands under a single 'i2c' root command.  The
1296		older 'imm', 'imd', 'iprobe' etc. commands are considered
1297		deprecated and may disappear in the future.
1298
1299		CONFIG_HARD_I2C selects a hardware I2C controller.
1300
1301		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1302		bit-banging) driver instead of CPM or similar hardware
1303		support for I2C.
1304
1305		There are several other quantities that must also be
1306		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1307
1308		In both cases you will need to define CFG_I2C_SPEED
1309		to be the frequency (in Hz) at which you wish your i2c bus
1310		to run and CFG_I2C_SLAVE to be the address of this node (ie
1311		the cpu's i2c node address).
1312
1313		Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
1314		sets the cpu up as a master node and so its address should
1315		therefore be cleared to 0 (See, eg, MPC823e User's Manual
1316		p.16-473). So, set CFG_I2C_SLAVE to 0.
1317
1318		That's all that's required for CONFIG_HARD_I2C.
1319
1320		If you use the software i2c interface (CONFIG_SOFT_I2C)
1321		then the following macros need to be defined (examples are
1322		from include/configs/lwmon.h):
1323
1324		I2C_INIT
1325
1326		(Optional). Any commands necessary to enable the I2C
1327		controller or configure ports.
1328
1329		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
1330
1331		I2C_PORT
1332
1333		(Only for MPC8260 CPU). The I/O port to use (the code
1334		assumes both bits are on the same port). Valid values
1335		are 0..3 for ports A..D.
1336
1337		I2C_ACTIVE
1338
1339		The code necessary to make the I2C data line active
1340		(driven).  If the data line is open collector, this
1341		define can be null.
1342
1343		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1344
1345		I2C_TRISTATE
1346
1347		The code necessary to make the I2C data line tri-stated
1348		(inactive).  If the data line is open collector, this
1349		define can be null.
1350
1351		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1352
1353		I2C_READ
1354
1355		Code that returns TRUE if the I2C data line is high,
1356		FALSE if it is low.
1357
1358		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1359
1360		I2C_SDA(bit)
1361
1362		If <bit> is TRUE, sets the I2C data line high. If it
1363		is FALSE, it clears it (low).
1364
1365		eg: #define I2C_SDA(bit) \
1366			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1367			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
1368
1369		I2C_SCL(bit)
1370
1371		If <bit> is TRUE, sets the I2C clock line high. If it
1372		is FALSE, it clears it (low).
1373
1374		eg: #define I2C_SCL(bit) \
1375			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1376			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
1377
1378		I2C_DELAY
1379
1380		This delay is invoked four times per clock cycle so this
1381		controls the rate of data transfer.  The data rate thus
1382		is 1 / (I2C_DELAY * 4). Often defined to be something
1383		like:
1384
1385		#define I2C_DELAY  udelay(2)
1386
1387		CFG_I2C_INIT_BOARD
1388
1389		When a board is reset during an i2c bus transfer
1390		chips might think that the current transfer is still
1391		in progress. On some boards it is possible to access
1392		the i2c SCLK line directly, either by using the
1393		processor pin as a GPIO or by having a second pin
1394		connected to the bus. If this option is defined a
1395		custom i2c_init_board() routine in boards/xxx/board.c
1396		is run early in the boot sequence.
1397
1398		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1399
1400		This option enables configuration of bi_iic_fast[] flags
1401		in u-boot bd_info structure based on u-boot environment
1402		variable "i2cfast". (see also i2cfast)
1403
1404		CONFIG_I2C_MULTI_BUS
1405
1406		This option allows the use of multiple I2C buses, each of which
1407		must have a controller.  At any point in time, only one bus is
1408		active.  To switch to a different bus, use the 'i2c dev' command.
1409		Note that bus numbering is zero-based.
1410
1411		CFG_I2C_NOPROBES
1412
1413		This option specifies a list of I2C devices that will be skipped
1414		when the 'i2c probe' command is issued (or 'iprobe' using the legacy
1415		command).  If CONFIG_I2C_MULTI_BUS is set, specify a list of bus-device
1416		pairs.  Otherwise, specify a 1D array of device addresses
1417
1418		e.g.
1419			#undef	CONFIG_I2C_MULTI_BUS
1420			#define CFG_I2C_NOPROBES	{0x50,0x68}
1421
1422		will skip addresses 0x50 and 0x68 on a board with one I2C bus
1423
1424			#define	CONFIG_I2C_MULTI_BUS
1425			#define CFG_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
1426
1427		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1428
1429		CFG_SPD_BUS_NUM
1430
1431		If defined, then this indicates the I2C bus number for DDR SPD.
1432		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1433
1434		CFG_RTC_BUS_NUM
1435
1436		If defined, then this indicates the I2C bus number for the RTC.
1437		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1438
1439		CFG_DTT_BUS_NUM
1440
1441		If defined, then this indicates the I2C bus number for the DTT.
1442		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
1443
1444		CONFIG_FSL_I2C
1445
1446		Define this option if you want to use Freescale's I2C driver in
1447		drivers/fsl_i2c.c.
1448
1449
1450- SPI Support:	CONFIG_SPI
1451
1452		Enables SPI driver (so far only tested with
1453		SPI EEPROM, also an instance works with Crystal A/D and
1454		D/As on the SACSng board)
1455
1456		CONFIG_SPI_X
1457
1458		Enables extended (16-bit) SPI EEPROM addressing.
1459		(symmetrical to CONFIG_I2C_X)
1460
1461		CONFIG_SOFT_SPI
1462
1463		Enables a software (bit-bang) SPI driver rather than
1464		using hardware support. This is a general purpose
1465		driver that only requires three general I/O port pins
1466		(two outputs, one input) to function. If this is
1467		defined, the board configuration must define several
1468		SPI configuration items (port pins to use, etc). For
1469		an example, see include/configs/sacsng.h.
1470
1471- FPGA Support: CONFIG_FPGA_COUNT
1472
1473		Specify the number of FPGA devices to support.
1474
1475		CONFIG_FPGA
1476
1477		Used to specify the types of FPGA devices.  For example,
1478		#define CONFIG_FPGA  CFG_XILINX_VIRTEX2
1479
1480		CFG_FPGA_PROG_FEEDBACK
1481
1482		Enable printing of hash marks during FPGA configuration.
1483
1484		CFG_FPGA_CHECK_BUSY
1485
1486		Enable checks on FPGA configuration interface busy
1487		status by the configuration function. This option
1488		will require a board or device specific function to
1489		be written.
1490
1491		CONFIG_FPGA_DELAY
1492
1493		If defined, a function that provides delays in the FPGA
1494		configuration driver.
1495
1496		CFG_FPGA_CHECK_CTRLC
1497		Allow Control-C to interrupt FPGA configuration
1498
1499		CFG_FPGA_CHECK_ERROR
1500
1501		Check for configuration errors during FPGA bitfile
1502		loading. For example, abort during Virtex II
1503		configuration if the INIT_B line goes low (which
1504		indicated a CRC error).
1505
1506		CFG_FPGA_WAIT_INIT
1507
1508		Maximum time to wait for the INIT_B line to deassert
1509		after PROB_B has been deasserted during a Virtex II
1510		FPGA configuration sequence. The default time is 500
1511		mS.
1512
1513		CFG_FPGA_WAIT_BUSY
1514
1515		Maximum time to wait for BUSY to deassert during
1516		Virtex II FPGA configuration. The default is 5 mS.
1517
1518		CFG_FPGA_WAIT_CONFIG
1519
1520		Time to wait after FPGA configuration. The default is
1521		200 mS.
1522
1523- Configuration Management:
1524		CONFIG_IDENT_STRING
1525
1526		If defined, this string will be added to the U-Boot
1527		version information (U_BOOT_VERSION)
1528
1529- Vendor Parameter Protection:
1530
1531		U-Boot considers the values of the environment
1532		variables "serial#" (Board Serial Number) and
1533		"ethaddr" (Ethernet Address) to be parameters that
1534		are set once by the board vendor / manufacturer, and
1535		protects these variables from casual modification by
1536		the user. Once set, these variables are read-only,
1537		and write or delete attempts are rejected. You can
1538		change this behviour:
1539
1540		If CONFIG_ENV_OVERWRITE is #defined in your config
1541		file, the write protection for vendor parameters is
1542		completely disabled. Anybody can change or delete
1543		these parameters.
1544
1545		Alternatively, if you #define _both_ CONFIG_ETHADDR
1546		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1547		ethernet address is installed in the environment,
1548		which can be changed exactly ONCE by the user. [The
1549		serial# is unaffected by this, i. e. it remains
1550		read-only.]
1551
1552- Protected RAM:
1553		CONFIG_PRAM
1554
1555		Define this variable to enable the reservation of
1556		"protected RAM", i. e. RAM which is not overwritten
1557		by U-Boot. Define CONFIG_PRAM to hold the number of
1558		kB you want to reserve for pRAM. You can overwrite
1559		this default value by defining an environment
1560		variable "pram" to the number of kB you want to
1561		reserve. Note that the board info structure will
1562		still show the full amount of RAM. If pRAM is
1563		reserved, a new environment variable "mem" will
1564		automatically be defined to hold the amount of
1565		remaining RAM in a form that can be passed as boot
1566		argument to Linux, for instance like that:
1567
1568			setenv bootargs ... mem=\${mem}
1569			saveenv
1570
1571		This way you can tell Linux not to use this memory,
1572		either, which results in a memory region that will
1573		not be affected by reboots.
1574
1575		*WARNING* If your board configuration uses automatic
1576		detection of the RAM size, you must make sure that
1577		this memory test is non-destructive. So far, the
1578		following board configurations are known to be
1579		"pRAM-clean":
1580
1581			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1582			HERMES, IP860, RPXlite, LWMON, LANTEC,
1583			PCU_E, FLAGADM, TQM8260
1584
1585- Error Recovery:
1586		CONFIG_PANIC_HANG
1587
1588		Define this variable to stop the system in case of a
1589		fatal error, so that you have to reset it manually.
1590		This is probably NOT a good idea for an embedded
1591		system where you want to system to reboot
1592		automatically as fast as possible, but it may be
1593		useful during development since you can try to debug
1594		the conditions that lead to the situation.
1595
1596		CONFIG_NET_RETRY_COUNT
1597
1598		This variable defines the number of retries for
1599		network operations like ARP, RARP, TFTP, or BOOTP
1600		before giving up the operation. If not defined, a
1601		default value of 5 is used.
1602
1603- Command Interpreter:
1604		CONFIG_AUTO_COMPLETE
1605
1606		Enable auto completion of commands using TAB.
1607
1608		Note that this feature has NOT been implemented yet
1609		for the "hush" shell.
1610
1611
1612		CFG_HUSH_PARSER
1613
1614		Define this variable to enable the "hush" shell (from
1615		Busybox) as command line interpreter, thus enabling
1616		powerful command line syntax like
1617		if...then...else...fi conditionals or `&&' and '||'
1618		constructs ("shell scripts").
1619
1620		If undefined, you get the old, much simpler behaviour
1621		with a somewhat smaller memory footprint.
1622
1623
1624		CFG_PROMPT_HUSH_PS2
1625
1626		This defines the secondary prompt string, which is
1627		printed when the command interpreter needs more input
1628		to complete a command. Usually "> ".
1629
1630	Note:
1631
1632		In the current implementation, the local variables
1633		space and global environment variables space are
1634		separated. Local variables are those you define by
1635		simply typing `name=value'. To access a local
1636		variable later on, you have write `$name' or
1637		`${name}'; to execute the contents of a variable
1638		directly type `$name' at the command prompt.
1639
1640		Global environment variables are those you use
1641		setenv/printenv to work with. To run a command stored
1642		in such a variable, you need to use the run command,
1643		and you must not use the '$' sign to access them.
1644
1645		To store commands and special characters in a
1646		variable, please use double quotation marks
1647		surrounding the whole text of the variable, instead
1648		of the backslashes before semicolons and special
1649		symbols.
1650
1651- Commandline Editing and History:
1652		CONFIG_CMDLINE_EDITING
1653
1654		Enable editiong and History functions for interactive
1655		commandline input operations
1656
1657- Default Environment:
1658		CONFIG_EXTRA_ENV_SETTINGS
1659
1660		Define this to contain any number of null terminated
1661		strings (variable = value pairs) that will be part of
1662		the default environment compiled into the boot image.
1663
1664		For example, place something like this in your
1665		board's config file:
1666
1667		#define CONFIG_EXTRA_ENV_SETTINGS \
1668			"myvar1=value1\0" \
1669			"myvar2=value2\0"
1670
1671		Warning: This method is based on knowledge about the
1672		internal format how the environment is stored by the
1673		U-Boot code. This is NOT an official, exported
1674		interface! Although it is unlikely that this format
1675		will change soon, there is no guarantee either.
1676		You better know what you are doing here.
1677
1678		Note: overly (ab)use of the default environment is
1679		discouraged. Make sure to check other ways to preset
1680		the environment like the autoscript function or the
1681		boot command first.
1682
1683- DataFlash Support:
1684		CONFIG_HAS_DATAFLASH
1685
1686		Defining this option enables DataFlash features and
1687		allows to read/write in Dataflash via the standard
1688		commands cp, md...
1689
1690- SystemACE Support:
1691		CONFIG_SYSTEMACE
1692
1693		Adding this option adds support for Xilinx SystemACE
1694		chips attached via some sort of local bus. The address
1695		of the chip must alsh be defined in the
1696		CFG_SYSTEMACE_BASE macro. For example:
1697
1698		#define CONFIG_SYSTEMACE
1699		#define CFG_SYSTEMACE_BASE 0xf0000000
1700
1701		When SystemACE support is added, the "ace" device type
1702		becomes available to the fat commands, i.e. fatls.
1703
1704- TFTP Fixed UDP Port:
1705		CONFIG_TFTP_PORT
1706
1707		If this is defined, the environment variable tftpsrcp
1708		is used to supply the TFTP UDP source port value.
1709		If tftpsrcp isn't defined, the normal pseudo-random port
1710		number generator is used.
1711
1712		Also, the environment variable tftpdstp is used to supply
1713		the TFTP UDP destination port value.  If tftpdstp isn't
1714		defined, the normal port 69 is used.
1715
1716		The purpose for tftpsrcp is to allow a TFTP server to
1717		blindly start the TFTP transfer using the pre-configured
1718		target IP address and UDP port. This has the effect of
1719		"punching through" the (Windows XP) firewall, allowing
1720		the remainder of the TFTP transfer to proceed normally.
1721		A better solution is to properly configure the firewall,
1722		but sometimes that is not allowed.
1723
1724- Show boot progress:
1725		CONFIG_SHOW_BOOT_PROGRESS
1726
1727		Defining this option allows to add some board-
1728		specific code (calling a user-provided function
1729		"show_boot_progress(int)") that enables you to show
1730		the system's boot progress on some display (for
1731		example, some LED's) on your board. At the moment,
1732		the following checkpoints are implemented:
1733
1734  Arg	Where			When
1735    1	common/cmd_bootm.c	before attempting to boot an image
1736   -1	common/cmd_bootm.c	Image header has bad	 magic number
1737    2	common/cmd_bootm.c	Image header has correct magic number
1738   -2	common/cmd_bootm.c	Image header has bad	 checksum
1739    3	common/cmd_bootm.c	Image header has correct checksum
1740   -3	common/cmd_bootm.c	Image data   has bad	 checksum
1741    4	common/cmd_bootm.c	Image data   has correct checksum
1742   -4	common/cmd_bootm.c	Image is for unsupported architecture
1743    5	common/cmd_bootm.c	Architecture check OK
1744   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi, standalone)
1745    6	common/cmd_bootm.c	Image Type check OK
1746   -6	common/cmd_bootm.c	gunzip uncompression error
1747   -7	common/cmd_bootm.c	Unimplemented compression type
1748    7	common/cmd_bootm.c	Uncompression OK
1749   -8	common/cmd_bootm.c	Wrong Image Type (not kernel, multi, standalone)
1750    8	common/cmd_bootm.c	Image Type check OK
1751   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
1752    9	common/cmd_bootm.c	Start initial ramdisk verification
1753  -10	common/cmd_bootm.c	Ramdisk header has bad	   magic number
1754  -11	common/cmd_bootm.c	Ramdisk header has bad	   checksum
1755   10	common/cmd_bootm.c	Ramdisk header is OK
1756  -12	common/cmd_bootm.c	Ramdisk data   has bad	   checksum
1757   11	common/cmd_bootm.c	Ramdisk data   has correct checksum
1758   12	common/cmd_bootm.c	Ramdisk verification complete, start loading
1759  -13	common/cmd_bootm.c	Wrong Image Type (not PPC Linux Ramdisk)
1760   13	common/cmd_bootm.c	Start multifile image verification
1761   14	common/cmd_bootm.c	No initial ramdisk, no multifile, continue.
1762   15	common/cmd_bootm.c	All preparation done, transferring control to OS
1763
1764  -30	lib_ppc/board.c		Fatal error, hang the system
1765  -31	post/post.c		POST test failed, detected by post_output_backlog()
1766  -32	post/post.c		POST test failed, detected by post_run_single()
1767
1768   -1	common/cmd_doc.c	Bad usage of "doc" command
1769   -1	common/cmd_doc.c	No boot device
1770   -1	common/cmd_doc.c	Unknown Chip ID on boot device
1771   -1	common/cmd_doc.c	Read Error on boot device
1772   -1	common/cmd_doc.c	Image header has bad magic number
1773
1774   -1	common/cmd_ide.c	Bad usage of "ide" command
1775   -1	common/cmd_ide.c	No boot device
1776   -1	common/cmd_ide.c	Unknown boot device
1777   -1	common/cmd_ide.c	Unknown partition table
1778   -1	common/cmd_ide.c	Invalid partition type
1779   -1	common/cmd_ide.c	Read Error on boot device
1780   -1	common/cmd_ide.c	Image header has bad magic number
1781
1782   -1	common/cmd_nand.c	Bad usage of "nand" command
1783   -1	common/cmd_nand.c	No boot device
1784   -1	common/cmd_nand.c	Unknown Chip ID on boot device
1785   -1	common/cmd_nand.c	Read Error on boot device
1786   -1	common/cmd_nand.c	Image header has bad magic number
1787
1788   -1	common/env_common.c	Environment has a bad CRC, using default
1789
1790
1791Modem Support:
1792--------------
1793
1794[so far only for SMDK2400 and TRAB boards]
1795
1796- Modem support endable:
1797		CONFIG_MODEM_SUPPORT
1798
1799- RTS/CTS Flow control enable:
1800		CONFIG_HWFLOW
1801
1802- Modem debug support:
1803		CONFIG_MODEM_SUPPORT_DEBUG
1804
1805		Enables debugging stuff (char screen[1024], dbg())
1806		for modem support. Useful only with BDI2000.
1807
1808- Interrupt support (PPC):
1809
1810		There are common interrupt_init() and timer_interrupt()
1811		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1812		for cpu specific initialization. interrupt_init_cpu()
1813		should set decrementer_count to appropriate value. If
1814		cpu resets decrementer automatically after interrupt
1815		(ppc4xx) it should set decrementer_count to zero.
1816		timer_interrupt() calls timer_interrupt_cpu() for cpu
1817		specific handling. If board has watchdog / status_led
1818		/ other_activity_monitor it works automatically from
1819		general timer_interrupt().
1820
1821- General:
1822
1823		In the target system modem support is enabled when a
1824		specific key (key combination) is pressed during
1825		power-on. Otherwise U-Boot will boot normally
1826		(autoboot). The key_pressed() fuction is called from
1827		board_init(). Currently key_pressed() is a dummy
1828		function, returning 1 and thus enabling modem
1829		initialization.
1830
1831		If there are no modem init strings in the
1832		environment, U-Boot proceed to autoboot; the
1833		previous output (banner, info printfs) will be
1834		supressed, though.
1835
1836		See also: doc/README.Modem
1837
1838
1839Configuration Settings:
1840-----------------------
1841
1842- CFG_LONGHELP: Defined when you want long help messages included;
1843		undefine this when you're short of memory.
1844
1845- CFG_PROMPT:	This is what U-Boot prints on the console to
1846		prompt for user input.
1847
1848- CFG_CBSIZE:	Buffer size for input from the Console
1849
1850- CFG_PBSIZE:	Buffer size for Console output
1851
1852- CFG_MAXARGS:	max. Number of arguments accepted for monitor commands
1853
1854- CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1855		the application (usually a Linux kernel) when it is
1856		booted
1857
1858- CFG_BAUDRATE_TABLE:
1859		List of legal baudrate settings for this board.
1860
1861- CFG_CONSOLE_INFO_QUIET
1862		Suppress display of console information at boot.
1863
1864- CFG_CONSOLE_IS_IN_ENV
1865		If the board specific function
1866			extern int overwrite_console (void);
1867		returns 1, the stdin, stderr and stdout are switched to the
1868		serial port, else the settings in the environment are used.
1869
1870- CFG_CONSOLE_OVERWRITE_ROUTINE
1871		Enable the call to overwrite_console().
1872
1873- CFG_CONSOLE_ENV_OVERWRITE
1874		Enable overwrite of previous console environment settings.
1875
1876- CFG_MEMTEST_START, CFG_MEMTEST_END:
1877		Begin and End addresses of the area used by the
1878		simple memory test.
1879
1880- CFG_ALT_MEMTEST:
1881		Enable an alternate, more extensive memory test.
1882
1883- CFG_MEMTEST_SCRATCH:
1884		Scratch address used by the alternate memory test
1885		You only need to set this if address zero isn't writeable
1886
1887- CFG_TFTP_LOADADDR:
1888		Default load address for network file downloads
1889
1890- CFG_LOADS_BAUD_CHANGE:
1891		Enable temporary baudrate change while serial download
1892
1893- CFG_SDRAM_BASE:
1894		Physical start address of SDRAM. _Must_ be 0 here.
1895
1896- CFG_MBIO_BASE:
1897		Physical start address of Motherboard I/O (if using a
1898		Cogent motherboard)
1899
1900- CFG_FLASH_BASE:
1901		Physical start address of Flash memory.
1902
1903- CFG_MONITOR_BASE:
1904		Physical start address of boot monitor code (set by
1905		make config files to be same as the text base address
1906		(TEXT_BASE) used when linking) - same as
1907		CFG_FLASH_BASE when booting from flash.
1908
1909- CFG_MONITOR_LEN:
1910		Size of memory reserved for monitor code, used to
1911		determine _at_compile_time_ (!) if the environment is
1912		embedded within the U-Boot image, or in a separate
1913		flash sector.
1914
1915- CFG_MALLOC_LEN:
1916		Size of DRAM reserved for malloc() use.
1917
1918- CFG_BOOTM_LEN:
1919		Normally compressed uImages are limited to an
1920		uncompressed size of 8 MBytes. If this is not enough,
1921		you can define CFG_BOOTM_LEN in your board config file
1922		to adjust this setting to your needs.
1923
1924- CFG_BOOTMAPSZ:
1925		Maximum size of memory mapped by the startup code of
1926		the Linux kernel; all data that must be processed by
1927		the Linux kernel (bd_info, boot arguments, eventually
1928		initrd image) must be put below this limit.
1929
1930- CFG_MAX_FLASH_BANKS:
1931		Max number of Flash memory banks
1932
1933- CFG_MAX_FLASH_SECT:
1934		Max number of sectors on a Flash chip
1935
1936- CFG_FLASH_ERASE_TOUT:
1937		Timeout for Flash erase operations (in ms)
1938
1939- CFG_FLASH_WRITE_TOUT:
1940		Timeout for Flash write operations (in ms)
1941
1942- CFG_FLASH_LOCK_TOUT
1943		Timeout for Flash set sector lock bit operation (in ms)
1944
1945- CFG_FLASH_UNLOCK_TOUT
1946		Timeout for Flash clear lock bits operation (in ms)
1947
1948- CFG_FLASH_PROTECTION
1949		If defined, hardware flash sectors protection is used
1950		instead of U-Boot software protection.
1951
1952- CFG_DIRECT_FLASH_TFTP:
1953
1954		Enable TFTP transfers directly to flash memory;
1955		without this option such a download has to be
1956		performed in two steps: (1) download to RAM, and (2)
1957		copy from RAM to flash.
1958
1959		The two-step approach is usually more reliable, since
1960		you can check if the download worked before you erase
1961		the flash, but in some situations (when sytem RAM is
1962		too limited to allow for a tempory copy of the
1963		downloaded image) this option may be very useful.
1964
1965- CFG_FLASH_CFI:
1966		Define if the flash driver uses extra elements in the
1967		common flash structure for storing flash geometry.
1968
1969- CFG_FLASH_CFI_DRIVER
1970		This option also enables the building of the cfi_flash driver
1971		in the drivers directory
1972
1973- CFG_FLASH_QUIET_TEST
1974		If this option is defined, the common CFI flash doesn't
1975		print it's warning upon not recognized FLASH banks. This
1976		is useful, if some of the configured banks are only
1977		optionally available.
1978
1979- CFG_RX_ETH_BUFFER:
1980		Defines the number of ethernet receive buffers. On some
1981		ethernet controllers it is recommended to set this value
1982		to 8 or even higher (EEPRO100 or 405 EMAC), since all
1983		buffers can be full shortly after enabling the interface
1984		on high ethernet traffic.
1985		Defaults to 4 if not defined.
1986
1987The following definitions that deal with the placement and management
1988of environment data (variable area); in general, we support the
1989following configurations:
1990
1991- CFG_ENV_IS_IN_FLASH:
1992
1993	Define this if the environment is in flash memory.
1994
1995	a) The environment occupies one whole flash sector, which is
1996	   "embedded" in the text segment with the U-Boot code. This
1997	   happens usually with "bottom boot sector" or "top boot
1998	   sector" type flash chips, which have several smaller
1999	   sectors at the start or the end. For instance, such a
2000	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
2001	   such a case you would place the environment in one of the
2002	   4 kB sectors - with U-Boot code before and after it. With
2003	   "top boot sector" type flash chips, you would put the
2004	   environment in one of the last sectors, leaving a gap
2005	   between U-Boot and the environment.
2006
2007	- CFG_ENV_OFFSET:
2008
2009	   Offset of environment data (variable area) to the
2010	   beginning of flash memory; for instance, with bottom boot
2011	   type flash chips the second sector can be used: the offset
2012	   for this sector is given here.
2013
2014	   CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
2015
2016	- CFG_ENV_ADDR:
2017
2018	   This is just another way to specify the start address of
2019	   the flash sector containing the environment (instead of
2020	   CFG_ENV_OFFSET).
2021
2022	- CFG_ENV_SECT_SIZE:
2023
2024	   Size of the sector containing the environment.
2025
2026
2027	b) Sometimes flash chips have few, equal sized, BIG sectors.
2028	   In such a case you don't want to spend a whole sector for
2029	   the environment.
2030
2031	- CFG_ENV_SIZE:
2032
2033	   If you use this in combination with CFG_ENV_IS_IN_FLASH
2034	   and CFG_ENV_SECT_SIZE, you can specify to use only a part
2035	   of this flash sector for the environment. This saves
2036	   memory for the RAM copy of the environment.
2037
2038	   It may also save flash memory if you decide to use this
2039	   when your environment is "embedded" within U-Boot code,
2040	   since then the remainder of the flash sector could be used
2041	   for U-Boot code. It should be pointed out that this is
2042	   STRONGLY DISCOURAGED from a robustness point of view:
2043	   updating the environment in flash makes it always
2044	   necessary to erase the WHOLE sector. If something goes
2045	   wrong before the contents has been restored from a copy in
2046	   RAM, your target system will be dead.
2047
2048	- CFG_ENV_ADDR_REDUND
2049	  CFG_ENV_SIZE_REDUND
2050
2051	   These settings describe a second storage area used to hold
2052	   a redundand copy of the environment data, so that there is
2053	   a valid backup copy in case there is a power failure during
2054	   a "saveenv" operation.
2055
2056BE CAREFUL! Any changes to the flash layout, and some changes to the
2057source code will make it necessary to adapt <board>/u-boot.lds*
2058accordingly!
2059
2060
2061- CFG_ENV_IS_IN_NVRAM:
2062
2063	Define this if you have some non-volatile memory device
2064	(NVRAM, battery buffered SRAM) which you want to use for the
2065	environment.
2066
2067	- CFG_ENV_ADDR:
2068	- CFG_ENV_SIZE:
2069
2070	  These two #defines are used to determin the memory area you
2071	  want to use for environment. It is assumed that this memory
2072	  can just be read and written to, without any special
2073	  provision.
2074
2075BE CAREFUL! The first access to the environment happens quite early
2076in U-Boot initalization (when we try to get the setting of for the
2077console baudrate). You *MUST* have mappend your NVRAM area then, or
2078U-Boot will hang.
2079
2080Please note that even with NVRAM we still use a copy of the
2081environment in RAM: we could work on NVRAM directly, but we want to
2082keep settings there always unmodified except somebody uses "saveenv"
2083to save the current settings.
2084
2085
2086- CFG_ENV_IS_IN_EEPROM:
2087
2088	Use this if you have an EEPROM or similar serial access
2089	device and a driver for it.
2090
2091	- CFG_ENV_OFFSET:
2092	- CFG_ENV_SIZE:
2093
2094	  These two #defines specify the offset and size of the
2095	  environment area within the total memory of your EEPROM.
2096
2097	- CFG_I2C_EEPROM_ADDR:
2098	  If defined, specified the chip address of the EEPROM device.
2099	  The default address is zero.
2100
2101	- CFG_EEPROM_PAGE_WRITE_BITS:
2102	  If defined, the number of bits used to address bytes in a
2103	  single page in the EEPROM device.  A 64 byte page, for example
2104	  would require six bits.
2105
2106	- CFG_EEPROM_PAGE_WRITE_DELAY_MS:
2107	  If defined, the number of milliseconds to delay between
2108	  page writes.	The default is zero milliseconds.
2109
2110	- CFG_I2C_EEPROM_ADDR_LEN:
2111	  The length in bytes of the EEPROM memory array address.  Note
2112	  that this is NOT the chip address length!
2113
2114	- CFG_I2C_EEPROM_ADDR_OVERFLOW:
2115	  EEPROM chips that implement "address overflow" are ones
2116	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
2117	  address and the extra bits end up in the "chip address" bit
2118	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
2119	  byte chips.
2120
2121	  Note that we consider the length of the address field to
2122	  still be one byte because the extra address bits are hidden
2123	  in the chip address.
2124
2125	- CFG_EEPROM_SIZE:
2126	  The size in bytes of the EEPROM device.
2127
2128
2129- CFG_ENV_IS_IN_DATAFLASH:
2130
2131	Define this if you have a DataFlash memory device which you
2132	want to use for the environment.
2133
2134	- CFG_ENV_OFFSET:
2135	- CFG_ENV_ADDR:
2136	- CFG_ENV_SIZE:
2137
2138	  These three #defines specify the offset and size of the
2139	  environment area within the total memory of your DataFlash placed
2140	  at the specified address.
2141
2142- CFG_ENV_IS_IN_NAND:
2143
2144	Define this if you have a NAND device which you want to use
2145	for the environment.
2146
2147	- CFG_ENV_OFFSET:
2148	- CFG_ENV_SIZE:
2149
2150	  These two #defines specify the offset and size of the environment
2151	  area within the first NAND device.
2152
2153	- CFG_ENV_OFFSET_REDUND
2154
2155	  This setting describes a second storage area of CFG_ENV_SIZE
2156	  size used to hold a redundant copy of the environment data,
2157	  so that there is a valid backup copy in case there is a
2158	  power failure during a "saveenv" operation.
2159
2160	Note: CFG_ENV_OFFSET and CFG_ENV_OFFSET_REDUND must be aligned
2161	to a block boundary, and CFG_ENV_SIZE must be a multiple of
2162	the NAND devices block size.
2163
2164- CFG_SPI_INIT_OFFSET
2165
2166	Defines offset to the initial SPI buffer area in DPRAM. The
2167	area is used at an early stage (ROM part) if the environment
2168	is configured to reside in the SPI EEPROM: We need a 520 byte
2169	scratch DPRAM area. It is used between the two initialization
2170	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
2171	to be a good choice since it makes it far enough from the
2172	start of the data area as well as from the stack pointer.
2173
2174Please note that the environment is read-only as long as the monitor
2175has been relocated to RAM and a RAM copy of the environment has been
2176created; also, when using EEPROM you will have to use getenv_r()
2177until then to read environment variables.
2178
2179The environment is protected by a CRC32 checksum. Before the monitor
2180is relocated into RAM, as a result of a bad CRC you will be working
2181with the compiled-in default environment - *silently*!!! [This is
2182necessary, because the first environment variable we need is the
2183"baudrate" setting for the console - if we have a bad CRC, we don't
2184have any device yet where we could complain.]
2185
2186Note: once the monitor has been relocated, then it will complain if
2187the default environment is used; a new CRC is computed as soon as you
2188use the "saveenv" command to store a valid environment.
2189
2190- CFG_FAULT_ECHO_LINK_DOWN:
2191		Echo the inverted Ethernet link state to the fault LED.
2192
2193		Note: If this option is active, then CFG_FAULT_MII_ADDR
2194		      also needs to be defined.
2195
2196- CFG_FAULT_MII_ADDR:
2197		MII address of the PHY to check for the Ethernet link state.
2198
2199- CFG_64BIT_VSPRINTF:
2200		Makes vsprintf (and all *printf functions) support printing
2201		of 64bit values by using the L quantifier
2202
2203- CFG_64BIT_STRTOUL:
2204		Adds simple_strtoull that returns a 64bit value
2205
2206Low Level (hardware related) configuration options:
2207---------------------------------------------------
2208
2209- CFG_CACHELINE_SIZE:
2210		Cache Line Size of the CPU.
2211
2212- CFG_DEFAULT_IMMR:
2213		Default address of the IMMR after system reset.
2214
2215		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
2216		and RPXsuper) to be able to adjust the position of
2217		the IMMR register after a reset.
2218
2219- Floppy Disk Support:
2220		CFG_FDC_DRIVE_NUMBER
2221
2222		the default drive number (default value 0)
2223
2224		CFG_ISA_IO_STRIDE
2225
2226		defines the spacing between fdc chipset registers
2227		(default value 1)
2228
2229		CFG_ISA_IO_OFFSET
2230
2231		defines the offset of register from address. It
2232		depends on which part of the data bus is connected to
2233		the fdc chipset. (default value 0)
2234
2235		If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
2236		CFG_FDC_DRIVE_NUMBER are undefined, they take their
2237		default value.
2238
2239		if CFG_FDC_HW_INIT is defined, then the function
2240		fdc_hw_init() is called at the beginning of the FDC
2241		setup. fdc_hw_init() must be provided by the board
2242		source code. It is used to make hardware dependant
2243		initializations.
2244
2245- CFG_IMMR:	Physical address of the Internal Memory.
2246		DO NOT CHANGE unless you know exactly what you're
2247		doing! (11-4) [MPC8xx/82xx systems only]
2248
2249- CFG_INIT_RAM_ADDR:
2250
2251		Start address of memory area that can be used for
2252		initial data and stack; please note that this must be
2253		writable memory that is working WITHOUT special
2254		initialization, i. e. you CANNOT use normal RAM which
2255		will become available only after programming the
2256		memory controller and running certain initialization
2257		sequences.
2258
2259		U-Boot uses the following memory types:
2260		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
2261		- MPC824X: data cache
2262		- PPC4xx:  data cache
2263
2264- CFG_GBL_DATA_OFFSET:
2265
2266		Offset of the initial data structure in the memory
2267		area defined by CFG_INIT_RAM_ADDR. Usually
2268		CFG_GBL_DATA_OFFSET is chosen such that the initial
2269		data is located at the end of the available space
2270		(sometimes written as (CFG_INIT_RAM_END -
2271		CFG_INIT_DATA_SIZE), and the initial stack is just
2272		below that area (growing from (CFG_INIT_RAM_ADDR +
2273		CFG_GBL_DATA_OFFSET) downward.
2274
2275	Note:
2276		On the MPC824X (or other systems that use the data
2277		cache for initial memory) the address chosen for
2278		CFG_INIT_RAM_ADDR is basically arbitrary - it must
2279		point to an otherwise UNUSED address space between
2280		the top of RAM and the start of the PCI space.
2281
2282- CFG_SIUMCR:	SIU Module Configuration (11-6)
2283
2284- CFG_SYPCR:	System Protection Control (11-9)
2285
2286- CFG_TBSCR:	Time Base Status and Control (11-26)
2287
2288- CFG_PISCR:	Periodic Interrupt Status and Control (11-31)
2289
2290- CFG_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
2291
2292- CFG_SCCR:	System Clock and reset Control Register (15-27)
2293
2294- CFG_OR_TIMING_SDRAM:
2295		SDRAM timing
2296
2297- CFG_MAMR_PTA:
2298		periodic timer for refresh
2299
2300- CFG_DER:	Debug Event Register (37-47)
2301
2302- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
2303  CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
2304  CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
2305  CFG_BR1_PRELIM:
2306		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2307
2308- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2309  CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
2310  CFG_OR3_PRELIM, CFG_BR3_PRELIM:
2311		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2312
2313- CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
2314  CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
2315		Machine Mode Register and Memory Periodic Timer
2316		Prescaler definitions (SDRAM timing)
2317
2318- CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
2319		enable I2C microcode relocation patch (MPC8xx);
2320		define relocation offset in DPRAM [DSP2]
2321
2322- CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
2323		enable SPI microcode relocation patch (MPC8xx);
2324		define relocation offset in DPRAM [SCC4]
2325
2326- CFG_USE_OSCCLK:
2327		Use OSCM clock mode on MBX8xx board. Be careful,
2328		wrong setting might damage your board. Read
2329		doc/README.MBX before setting this variable!
2330
2331- CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
2332		Offset of the bootmode word in DPRAM used by post
2333		(Power On Self Tests). This definition overrides
2334		#define'd default value in commproc.h resp.
2335		cpm_8260.h.
2336
2337- CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
2338  CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
2339  CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
2340  CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
2341  CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
2342  CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
2343  CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
2344  CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
2345		Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
2346
2347- CONFIG_SPD_EEPROM
2348		Get DDR timing information from an I2C EEPROM.  Common with pluggable
2349		memory modules such as SODIMMs
2350  SPD_EEPROM_ADDRESS
2351		I2C address of the SPD EEPROM
2352
2353- CFG_SPD_BUS_NUM
2354		If SPD EEPROM is on an I2C bus other than the first one, specify here.
2355		Note that the value must resolve to something your driver can deal with.
2356
2357- CFG_83XX_DDR_USES_CS0
2358		Only for 83xx systems. If specified, then DDR should be configured
2359		using CS0 and CS1 instead of CS2 and CS3.
2360
2361- CFG_83XX_DDR_USES_CS0
2362		Only for 83xx systems. If specified, then DDR should be configured
2363		using CS0 and CS1 instead of CS2 and CS3.
2364
2365- CONFIG_ETHER_ON_FEC[12]
2366		Define to enable FEC[12] on a 8xx series processor.
2367
2368- CONFIG_FEC[12]_PHY
2369		Define to the hardcoded PHY address which corresponds
2370		to the given FEC; i. e.
2371			#define CONFIG_FEC1_PHY 4
2372		means that the PHY with address 4 is connected to FEC1
2373
2374		When set to -1, means to probe for first available.
2375
2376- CONFIG_FEC[12]_PHY_NORXERR
2377		The PHY does not have a RXERR line (RMII only).
2378		(so program the FEC to ignore it).
2379
2380- CONFIG_RMII
2381		Enable RMII mode for all FECs.
2382		Note that this is a global option, we can't
2383		have one FEC in standard MII mode and another in RMII mode.
2384
2385- CONFIG_CRC32_VERIFY
2386		Add a verify option to the crc32 command.
2387		The syntax is:
2388
2389		=> crc32 -v <address> <count> <crc32>
2390
2391		Where address/count indicate a memory area
2392		and crc32 is the correct crc32 which the
2393		area should have.
2394
2395- CONFIG_LOOPW
2396		Add the "loopw" memory command. This only takes effect if
2397		the memory commands are activated globally (CFG_CMD_MEM).
2398
2399- CONFIG_MX_CYCLIC
2400		Add the "mdc" and "mwc" memory commands. These are cyclic
2401		"md/mw" commands.
2402		Examples:
2403
2404		=> mdc.b 10 4 500
2405		This command will print 4 bytes (10,11,12,13) each 500 ms.
2406
2407		=> mwc.l 100 12345678 10
2408		This command will write 12345678 to address 100 all 10 ms.
2409
2410		This only takes effect if the memory commands are activated
2411		globally (CFG_CMD_MEM).
2412
2413- CONFIG_SKIP_LOWLEVEL_INIT
2414- CONFIG_SKIP_RELOCATE_UBOOT
2415
2416		[ARM only] If these variables are defined, then
2417		certain low level initializations (like setting up
2418		the memory controller) are omitted and/or U-Boot does
2419		not relocate itself into RAM.
2420		Normally these variables MUST NOT be defined. The
2421		only exception is when U-Boot is loaded (to RAM) by
2422		some other boot loader or by a debugger which
2423		performs these intializations itself.
2424
2425
2426Building the Software:
2427======================
2428
2429Building U-Boot has been tested in native PPC environments (on a
2430PowerBook G3 running LinuxPPC 2000) and in cross environments
2431(running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
2432NetBSD 1.5 on x86).
2433
2434If you are not using a native PPC environment, it is assumed that you
2435have the GNU cross compiling tools available in your path and named
2436with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
2437you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
2438the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
2439change it to:
2440
2441	CROSS_COMPILE = ppc_4xx-
2442
2443
2444U-Boot is intended to be  simple  to  build.  After  installing	 the
2445sources	 you must configure U-Boot for one specific board type. This
2446is done by typing:
2447
2448	make NAME_config
2449
2450where "NAME_config" is the name of one of the existing
2451configurations; the following names are supported:
2452
2453	ADCIOP_config		FPS860L_config		omap730p2_config
2454	ADS860_config		GEN860T_config		pcu_e_config
2455	Alaska8220_config
2456	AR405_config		GENIETV_config		PIP405_config
2457	at91rm9200dk_config	GTH_config		QS823_config
2458	CANBT_config		hermes_config		QS850_config
2459	cmi_mpc5xx_config	hymod_config		QS860T_config
2460	cogent_common_config	IP860_config		RPXlite_config
2461	cogent_mpc8260_config	IVML24_config		RPXlite_DW_config
2462	cogent_mpc8xx_config	IVMS8_config		RPXsuper_config
2463	CPCI405_config		JSE_config		rsdproto_config
2464	CPCIISER4_config	LANTEC_config		Sandpoint8240_config
2465	csb272_config		lwmon_config		sbc8260_config
2466	CU824_config		MBX860T_config		sbc8560_33_config
2467	DUET_ADS_config		MBX_config		sbc8560_66_config
2468	EBONY_config		mpc7448hpc2_config	SM850_config
2469	ELPT860_config		MPC8260ADS_config	SPD823TS_config
2470	ESTEEM192E_config	MPC8540ADS_config	stxgp3_config
2471	ETX094_config		MPC8540EVAL_config	SXNI855T_config
2472	FADS823_config		NMPC8560ADS_config	TQM823L_config
2473	FADS850SAR_config	NETVIA_config		TQM850L_config
2474	FADS860T_config		omap1510inn_config	TQM855L_config
2475	FPS850L_config		omap1610h2_config	TQM860L_config
2476				omap1610inn_config	walnut_config
2477				omap5912osk_config	Yukon8220_config
2478				omap2420h4_config	ZPC1900_config
2479
2480Note: for some board special configuration names may exist; check if
2481      additional information is available from the board vendor; for
2482      instance, the TQM823L systems are available without (standard)
2483      or with LCD support. You can select such additional "features"
2484      when chosing the configuration, i. e.
2485
2486      make TQM823L_config
2487	- will configure for a plain TQM823L, i. e. no LCD support
2488
2489      make TQM823L_LCD_config
2490	- will configure for a TQM823L with U-Boot console on LCD
2491
2492      etc.
2493
2494
2495Finally, type "make all", and you should get some working U-Boot
2496images ready for download to / installation on your system:
2497
2498- "u-boot.bin" is a raw binary image
2499- "u-boot" is an image in ELF binary format
2500- "u-boot.srec" is in Motorola S-Record format
2501
2502By default the build is performed locally and the objects are saved
2503in the source directory. One of the two methods can be used to change
2504this behavior and build U-Boot to some external directory:
2505
25061. Add O= to the make command line invocations:
2507
2508	make O=/tmp/build distclean
2509	make O=/tmp/build NAME_config
2510	make O=/tmp/build all
2511
25122. Set environment variable BUILD_DIR to point to the desired location:
2513
2514	export BUILD_DIR=/tmp/build
2515	make distclean
2516	make NAME_config
2517	make all
2518
2519Note that the command line "O=" setting overrides the BUILD_DIR environment
2520variable.
2521
2522
2523Please be aware that the Makefiles assume you are using GNU make, so
2524for instance on NetBSD you might need to use "gmake" instead of
2525native "make".
2526
2527
2528If the system board that you have is not listed, then you will need
2529to port U-Boot to your hardware platform. To do this, follow these
2530steps:
2531
25321.  Add a new configuration option for your board to the toplevel
2533    "Makefile" and to the "MAKEALL" script, using the existing
2534    entries as examples. Note that here and at many other places
2535    boards and other names are listed in alphabetical sort order. Please
2536    keep this order.
25372.  Create a new directory to hold your board specific code. Add any
2538    files you need. In your board directory, you will need at least
2539    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
25403.  Create a new configuration file "include/configs/<board>.h" for
2541    your board
25423.  If you're porting U-Boot to a new CPU, then also create a new
2543    directory to hold your CPU specific code. Add any files you need.
25444.  Run "make <board>_config" with your new name.
25455.  Type "make", and you should get a working "u-boot.srec" file
2546    to be installed on your target system.
25476.  Debug and solve any problems that might arise.
2548    [Of course, this last step is much harder than it sounds.]
2549
2550
2551Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2552==============================================================
2553
2554If you have modified U-Boot sources (for instance added a new	board
2555or  support  for  new  devices,	 a new CPU, etc.) you are expected to
2556provide feedback to the other developers. The feedback normally takes
2557the form of a "patch", i. e. a context diff against a certain (latest
2558official or latest in CVS) version of U-Boot sources.
2559
2560But before you submit such a patch, please verify that	your  modifi-
2561cation	did not break existing code. At least make sure that *ALL* of
2562the supported boards compile WITHOUT ANY compiler warnings. To do so,
2563just run the "MAKEALL" script, which will configure and build U-Boot
2564for ALL supported system. Be warned, this will take a while. You  can
2565select	which  (cross)	compiler  to use by passing a `CROSS_COMPILE'
2566environment variable to the script, i. e. to use the cross tools from
2567MontaVista's Hard Hat Linux you can type
2568
2569	CROSS_COMPILE=ppc_8xx- MAKEALL
2570
2571or to build on a native PowerPC system you can type
2572
2573	CROSS_COMPILE=' ' MAKEALL
2574
2575When using the MAKEALL script, the default behaviour is to build U-Boot
2576in the source directory. This location can be changed by setting the
2577BUILD_DIR environment variable. Also, for each target built, the MAKEALL
2578script saves two log files (<target>.ERR and <target>.MAKEALL) in the
2579<source dir>/LOG directory. This default location can be changed by
2580setting the MAKEALL_LOGDIR environment variable. For example:
2581
2582	export BUILD_DIR=/tmp/build
2583	export MAKEALL_LOGDIR=/tmp/log
2584	CROSS_COMPILE=ppc_8xx- MAKEALL
2585
2586With the above settings build objects are saved in the /tmp/build, log
2587files are saved in the /tmp/log and the source tree remains clean during
2588the whole build process.
2589
2590
2591See also "U-Boot Porting Guide" below.
2592
2593
2594Monitor Commands - Overview:
2595============================
2596
2597go	- start application at address 'addr'
2598run	- run commands in an environment variable
2599bootm	- boot application image from memory
2600bootp	- boot image via network using BootP/TFTP protocol
2601tftpboot- boot image via network using TFTP protocol
2602	       and env variables "ipaddr" and "serverip"
2603	       (and eventually "gatewayip")
2604rarpboot- boot image via network using RARP/TFTP protocol
2605diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
2606loads	- load S-Record file over serial line
2607loadb	- load binary file over serial line (kermit mode)
2608md	- memory display
2609mm	- memory modify (auto-incrementing)
2610nm	- memory modify (constant address)
2611mw	- memory write (fill)
2612cp	- memory copy
2613cmp	- memory compare
2614crc32	- checksum calculation
2615imd	- i2c memory display
2616imm	- i2c memory modify (auto-incrementing)
2617inm	- i2c memory modify (constant address)
2618imw	- i2c memory write (fill)
2619icrc32	- i2c checksum calculation
2620iprobe	- probe to discover valid I2C chip addresses
2621iloop	- infinite loop on address range
2622isdram	- print SDRAM configuration information
2623sspi	- SPI utility commands
2624base	- print or set address offset
2625printenv- print environment variables
2626setenv	- set environment variables
2627saveenv - save environment variables to persistent storage
2628protect - enable or disable FLASH write protection
2629erase	- erase FLASH memory
2630flinfo	- print FLASH memory information
2631bdinfo	- print Board Info structure
2632iminfo	- print header information for application image
2633coninfo - print console devices and informations
2634ide	- IDE sub-system
2635loop	- infinite loop on address range
2636loopw	- infinite write loop on address range
2637mtest	- simple RAM test
2638icache	- enable or disable instruction cache
2639dcache	- enable or disable data cache
2640reset	- Perform RESET of the CPU
2641echo	- echo args to console
2642version - print monitor version
2643help	- print online help
2644?	- alias for 'help'
2645
2646
2647Monitor Commands - Detailed Description:
2648========================================
2649
2650TODO.
2651
2652For now: just type "help <command>".
2653
2654
2655Environment Variables:
2656======================
2657
2658U-Boot supports user configuration using Environment Variables which
2659can be made persistent by saving to Flash memory.
2660
2661Environment Variables are set using "setenv", printed using
2662"printenv", and saved to Flash using "saveenv". Using "setenv"
2663without a value can be used to delete a variable from the
2664environment. As long as you don't save the environment you are
2665working with an in-memory copy. In case the Flash area containing the
2666environment is erased by accident, a default environment is provided.
2667
2668Some configuration options can be set using Environment Variables:
2669
2670  baudrate	- see CONFIG_BAUDRATE
2671
2672  bootdelay	- see CONFIG_BOOTDELAY
2673
2674  bootcmd	- see CONFIG_BOOTCOMMAND
2675
2676  bootargs	- Boot arguments when booting an RTOS image
2677
2678  bootfile	- Name of the image to load with TFTP
2679
2680  autoload	- if set to "no" (any string beginning with 'n'),
2681		  "bootp" will just load perform a lookup of the
2682		  configuration from the BOOTP server, but not try to
2683		  load any image using TFTP
2684
2685  autostart	- if set to "yes", an image loaded using the "bootp",
2686		  "rarpboot", "tftpboot" or "diskboot" commands will
2687		  be automatically started (by internally calling
2688		  "bootm")
2689
2690		  If set to "no", a standalone image passed to the
2691		  "bootm" command will be copied to the load address
2692		  (and eventually uncompressed), but NOT be started.
2693		  This can be used to load and uncompress arbitrary
2694		  data.
2695
2696  i2cfast	- (PPC405GP|PPC405EP only)
2697		  if set to 'y' configures Linux I2C driver for fast
2698		  mode (400kHZ). This environment variable is used in
2699		  initialization code. So, for changes to be effective
2700		  it must be saved and board must be reset.
2701
2702  initrd_high	- restrict positioning of initrd images:
2703		  If this variable is not set, initrd images will be
2704		  copied to the highest possible address in RAM; this
2705		  is usually what you want since it allows for
2706		  maximum initrd size. If for some reason you want to
2707		  make sure that the initrd image is loaded below the
2708		  CFG_BOOTMAPSZ limit, you can set this environment
2709		  variable to a value of "no" or "off" or "0".
2710		  Alternatively, you can set it to a maximum upper
2711		  address to use (U-Boot will still check that it
2712		  does not overwrite the U-Boot stack and data).
2713
2714		  For instance, when you have a system with 16 MB
2715		  RAM, and want to reserve 4 MB from use by Linux,
2716		  you can do this by adding "mem=12M" to the value of
2717		  the "bootargs" variable. However, now you must make
2718		  sure that the initrd image is placed in the first
2719		  12 MB as well - this can be done with
2720
2721		  setenv initrd_high 00c00000
2722
2723		  If you set initrd_high to 0xFFFFFFFF, this is an
2724		  indication to U-Boot that all addresses are legal
2725		  for the Linux kernel, including addresses in flash
2726		  memory. In this case U-Boot will NOT COPY the
2727		  ramdisk at all. This may be useful to reduce the
2728		  boot time on your system, but requires that this
2729		  feature is supported by your Linux kernel.
2730
2731  ipaddr	- IP address; needed for tftpboot command
2732
2733  loadaddr	- Default load address for commands like "bootp",
2734		  "rarpboot", "tftpboot", "loadb" or "diskboot"
2735
2736  loads_echo	- see CONFIG_LOADS_ECHO
2737
2738  serverip	- TFTP server IP address; needed for tftpboot command
2739
2740  bootretry	- see CONFIG_BOOT_RETRY_TIME
2741
2742  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
2743
2744  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
2745
2746  ethprime	- When CONFIG_NET_MULTI is enabled controls which
2747		  interface is used first.
2748
2749  ethact	- When CONFIG_NET_MULTI is enabled controls which
2750		  interface is currently active. For example you
2751		  can do the following
2752
2753		  => setenv ethact FEC ETHERNET
2754		  => ping 192.168.0.1 # traffic sent on FEC ETHERNET
2755		  => setenv ethact SCC ETHERNET
2756		  => ping 10.0.0.1 # traffic sent on SCC ETHERNET
2757
2758   netretry	- When set to "no" each network operation will
2759		  either succeed or fail without retrying.
2760		  When set to "once" the network operation will
2761		  fail when all the available network interfaces
2762		  are tried once without success.
2763		  Useful on scripts which control the retry operation
2764		  themselves.
2765
2766  tftpsrcport	- If this is set, the value is used for TFTP's
2767		  UDP source port.
2768
2769  tftpdstport	- If this is set, the value is used for TFTP's UDP
2770		  destination port instead of the Well Know Port 69.
2771
2772   vlan		- When set to a value < 4095 the traffic over
2773		  ethernet is encapsulated/received over 802.1q
2774		  VLAN tagged frames.
2775
2776The following environment variables may be used and automatically
2777updated by the network boot commands ("bootp" and "rarpboot"),
2778depending the information provided by your boot server:
2779
2780  bootfile	- see above
2781  dnsip		- IP address of your Domain Name Server
2782  dnsip2	- IP address of your secondary Domain Name Server
2783  gatewayip	- IP address of the Gateway (Router) to use
2784  hostname	- Target hostname
2785  ipaddr	- see above
2786  netmask	- Subnet Mask
2787  rootpath	- Pathname of the root filesystem on the NFS server
2788  serverip	- see above
2789
2790
2791There are two special Environment Variables:
2792
2793  serial#	- contains hardware identification information such
2794		  as type string and/or serial number
2795  ethaddr	- Ethernet address
2796
2797These variables can be set only once (usually during manufacturing of
2798the board). U-Boot refuses to delete or overwrite these variables
2799once they have been set once.
2800
2801
2802Further special Environment Variables:
2803
2804  ver		- Contains the U-Boot version string as printed
2805		  with the "version" command. This variable is
2806		  readonly (see CONFIG_VERSION_VARIABLE).
2807
2808
2809Please note that changes to some configuration parameters may take
2810only effect after the next boot (yes, that's just like Windoze :-).
2811
2812
2813Command Line Parsing:
2814=====================
2815
2816There are two different command line parsers available with U-Boot:
2817the old "simple" one, and the much more powerful "hush" shell:
2818
2819Old, simple command line parser:
2820--------------------------------
2821
2822- supports environment variables (through setenv / saveenv commands)
2823- several commands on one line, separated by ';'
2824- variable substitution using "... ${name} ..." syntax
2825- special characters ('$', ';') can be escaped by prefixing with '\',
2826  for example:
2827	setenv bootcmd bootm \${address}
2828- You can also escape text by enclosing in single apostrophes, for example:
2829	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
2830
2831Hush shell:
2832-----------
2833
2834- similar to Bourne shell, with control structures like
2835  if...then...else...fi, for...do...done; while...do...done,
2836  until...do...done, ...
2837- supports environment ("global") variables (through setenv / saveenv
2838  commands) and local shell variables (through standard shell syntax
2839  "name=value"); only environment variables can be used with "run"
2840  command
2841
2842General rules:
2843--------------
2844
2845(1) If a command line (or an environment variable executed by a "run"
2846    command) contains several commands separated by semicolon, and
2847    one of these commands fails, then the remaining commands will be
2848    executed anyway.
2849
2850(2) If you execute several variables with one call to run (i. e.
2851    calling run with a list af variables as arguments), any failing
2852    command will cause "run" to terminate, i. e. the remaining
2853    variables are not executed.
2854
2855Note for Redundant Ethernet Interfaces:
2856=======================================
2857
2858Some boards come with redundant ethernet interfaces; U-Boot supports
2859such configurations and is capable of automatic selection of a
2860"working" interface when needed. MAC assignment works as follows:
2861
2862Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2863MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2864"eth1addr" (=>eth1), "eth2addr", ...
2865
2866If the network interface stores some valid MAC address (for instance
2867in SROM), this is used as default address if there is NO correspon-
2868ding setting in the environment; if the corresponding environment
2869variable is set, this overrides the settings in the card; that means:
2870
2871o If the SROM has a valid MAC address, and there is no address in the
2872  environment, the SROM's address is used.
2873
2874o If there is no valid address in the SROM, and a definition in the
2875  environment exists, then the value from the environment variable is
2876  used.
2877
2878o If both the SROM and the environment contain a MAC address, and
2879  both addresses are the same, this MAC address is used.
2880
2881o If both the SROM and the environment contain a MAC address, and the
2882  addresses differ, the value from the environment is used and a
2883  warning is printed.
2884
2885o If neither SROM nor the environment contain a MAC address, an error
2886  is raised.
2887
2888
2889Image Formats:
2890==============
2891
2892The "boot" commands of this monitor operate on "image" files which
2893can be basicly anything, preceeded by a special header; see the
2894definitions in include/image.h for details; basicly, the header
2895defines the following image properties:
2896
2897* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2898  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2899  LynxOS, pSOS, QNX, RTEMS, ARTOS;
2900  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, ARTOS, LynxOS).
2901* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
2902  IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2903  Currently supported: ARM, AVR32, Intel x86, MIPS, NIOS, PowerPC).
2904* Compression Type (uncompressed, gzip, bzip2)
2905* Load Address
2906* Entry Point
2907* Image Name
2908* Image Timestamp
2909
2910The header is marked by a special Magic Number, and both the header
2911and the data portions of the image are secured against corruption by
2912CRC32 checksums.
2913
2914
2915Linux Support:
2916==============
2917
2918Although U-Boot should support any OS or standalone application
2919easily, the main focus has always been on Linux during the design of
2920U-Boot.
2921
2922U-Boot includes many features that so far have been part of some
2923special "boot loader" code within the Linux kernel. Also, any
2924"initrd" images to be used are no longer part of one big Linux image;
2925instead, kernel and "initrd" are separate images. This implementation
2926serves several purposes:
2927
2928- the same features can be used for other OS or standalone
2929  applications (for instance: using compressed images to reduce the
2930  Flash memory footprint)
2931
2932- it becomes much easier to port new Linux kernel versions because
2933  lots of low-level, hardware dependent stuff are done by U-Boot
2934
2935- the same Linux kernel image can now be used with different "initrd"
2936  images; of course this also means that different kernel images can
2937  be run with the same "initrd". This makes testing easier (you don't
2938  have to build a new "zImage.initrd" Linux image when you just
2939  change a file in your "initrd"). Also, a field-upgrade of the
2940  software is easier now.
2941
2942
2943Linux HOWTO:
2944============
2945
2946Porting Linux to U-Boot based systems:
2947---------------------------------------
2948
2949U-Boot cannot save you from doing all the necessary modifications to
2950configure the Linux device drivers for use with your target hardware
2951(no, we don't intend to provide a full virtual machine interface to
2952Linux :-).
2953
2954But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
2955
2956Just make sure your machine specific header file (for instance
2957include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2958Information structure as we define in include/u-boot.h, and make
2959sure that your definition of IMAP_ADDR uses the same value as your
2960U-Boot configuration in CFG_IMMR.
2961
2962
2963Configuring the Linux kernel:
2964-----------------------------
2965
2966No specific requirements for U-Boot. Make sure you have some root
2967device (initial ramdisk, NFS) for your target system.
2968
2969
2970Building a Linux Image:
2971-----------------------
2972
2973With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2974not used. If you use recent kernel source, a new build target
2975"uImage" will exist which automatically builds an image usable by
2976U-Boot. Most older kernels also have support for a "pImage" target,
2977which was introduced for our predecessor project PPCBoot and uses a
2978100% compatible format.
2979
2980Example:
2981
2982	make TQM850L_config
2983	make oldconfig
2984	make dep
2985	make uImage
2986
2987The "uImage" build target uses a special tool (in 'tools/mkimage') to
2988encapsulate a compressed Linux kernel image with header	 information,
2989CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2990
2991* build a standard "vmlinux" kernel image (in ELF binary format):
2992
2993* convert the kernel into a raw binary image:
2994
2995	${CROSS_COMPILE}-objcopy -O binary \
2996				 -R .note -R .comment \
2997				 -S vmlinux linux.bin
2998
2999* compress the binary image:
3000
3001	gzip -9 linux.bin
3002
3003* package compressed binary image for U-Boot:
3004
3005	mkimage -A ppc -O linux -T kernel -C gzip \
3006		-a 0 -e 0 -n "Linux Kernel Image" \
3007		-d linux.bin.gz uImage
3008
3009
3010The "mkimage" tool can also be used to create ramdisk images for use
3011with U-Boot, either separated from the Linux kernel image, or
3012combined into one file. "mkimage" encapsulates the images with a 64
3013byte header containing information about target architecture,
3014operating system, image type, compression method, entry points, time
3015stamp, CRC32 checksums, etc.
3016
3017"mkimage" can be called in two ways: to verify existing images and
3018print the header information, or to build new images.
3019
3020In the first form (with "-l" option) mkimage lists the information
3021contained in the header of an existing U-Boot image; this includes
3022checksum verification:
3023
3024	tools/mkimage -l image
3025	  -l ==> list image header information
3026
3027The second form (with "-d" option) is used to build a U-Boot image
3028from a "data file" which is used as image payload:
3029
3030	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3031		      -n name -d data_file image
3032	  -A ==> set architecture to 'arch'
3033	  -O ==> set operating system to 'os'
3034	  -T ==> set image type to 'type'
3035	  -C ==> set compression type 'comp'
3036	  -a ==> set load address to 'addr' (hex)
3037	  -e ==> set entry point to 'ep' (hex)
3038	  -n ==> set image name to 'name'
3039	  -d ==> use image data from 'datafile'
3040
3041Right now, all Linux kernels for PowerPC systems use the same load
3042address (0x00000000), but the entry point address depends on the
3043kernel version:
3044
3045- 2.2.x kernels have the entry point at 0x0000000C,
3046- 2.3.x and later kernels have the entry point at 0x00000000.
3047
3048So a typical call to build a U-Boot image would read:
3049
3050	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3051	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3052	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
3053	> examples/uImage.TQM850L
3054	Image Name:   2.4.4 kernel for TQM850L
3055	Created:      Wed Jul 19 02:34:59 2000
3056	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3057	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
3058	Load Address: 0x00000000
3059	Entry Point:  0x00000000
3060
3061To verify the contents of the image (or check for corruption):
3062
3063	-> tools/mkimage -l examples/uImage.TQM850L
3064	Image Name:   2.4.4 kernel for TQM850L
3065	Created:      Wed Jul 19 02:34:59 2000
3066	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3067	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
3068	Load Address: 0x00000000
3069	Entry Point:  0x00000000
3070
3071NOTE: for embedded systems where boot time is critical you can trade
3072speed for memory and install an UNCOMPRESSED image instead: this
3073needs more space in Flash, but boots much faster since it does not
3074need to be uncompressed:
3075
3076	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
3077	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3078	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3079	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
3080	> examples/uImage.TQM850L-uncompressed
3081	Image Name:   2.4.4 kernel for TQM850L
3082	Created:      Wed Jul 19 02:34:59 2000
3083	Image Type:   PowerPC Linux Kernel Image (uncompressed)
3084	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
3085	Load Address: 0x00000000
3086	Entry Point:  0x00000000
3087
3088
3089Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3090when your kernel is intended to use an initial ramdisk:
3091
3092	-> tools/mkimage -n 'Simple Ramdisk Image' \
3093	> -A ppc -O linux -T ramdisk -C gzip \
3094	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3095	Image Name:   Simple Ramdisk Image
3096	Created:      Wed Jan 12 14:01:50 2000
3097	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
3098	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
3099	Load Address: 0x00000000
3100	Entry Point:  0x00000000
3101
3102
3103Installing a Linux Image:
3104-------------------------
3105
3106To downloading a U-Boot image over the serial (console) interface,
3107you must convert the image to S-Record format:
3108
3109	objcopy -I binary -O srec examples/image examples/image.srec
3110
3111The 'objcopy' does not understand the information in the U-Boot
3112image header, so the resulting S-Record file will be relative to
3113address 0x00000000. To load it to a given address, you need to
3114specify the target address as 'offset' parameter with the 'loads'
3115command.
3116
3117Example: install the image to address 0x40100000 (which on the
3118TQM8xxL is in the first Flash bank):
3119
3120	=> erase 40100000 401FFFFF
3121
3122	.......... done
3123	Erased 8 sectors
3124
3125	=> loads 40100000
3126	## Ready for S-Record download ...
3127	~>examples/image.srec
3128	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3129	...
3130	15989 15990 15991 15992
3131	[file transfer complete]
3132	[connected]
3133	## Start Addr = 0x00000000
3134
3135
3136You can check the success of the download using the 'iminfo' command;
3137this includes a checksum verification so you  can  be  sure  no	 data
3138corruption happened:
3139
3140	=> imi 40100000
3141
3142	## Checking Image at 40100000 ...
3143	   Image Name:	 2.2.13 for initrd on TQM850L
3144	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3145	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3146	   Load Address: 00000000
3147	   Entry Point:	 0000000c
3148	   Verifying Checksum ... OK
3149
3150
3151Boot Linux:
3152-----------
3153
3154The "bootm" command is used to boot an application that is stored in
3155memory (RAM or Flash). In case of a Linux kernel image, the contents
3156of the "bootargs" environment variable is passed to the kernel as
3157parameters. You can check and modify this variable using the
3158"printenv" and "setenv" commands:
3159
3160
3161	=> printenv bootargs
3162	bootargs=root=/dev/ram
3163
3164	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3165
3166	=> printenv bootargs
3167	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3168
3169	=> bootm 40020000
3170	## Booting Linux kernel at 40020000 ...
3171	   Image Name:	 2.2.13 for NFS on TQM850L
3172	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3173	   Data Size:	 381681 Bytes = 372 kB = 0 MB
3174	   Load Address: 00000000
3175	   Entry Point:	 0000000c
3176	   Verifying Checksum ... OK
3177	   Uncompressing Kernel Image ... OK
3178	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
3179	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3180	time_init: decrementer frequency = 187500000/60
3181	Calibrating delay loop... 49.77 BogoMIPS
3182	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3183	...
3184
3185If you want to boot a Linux kernel with initial ram disk, you pass
3186the memory addresses of both the kernel and the initrd image (PPBCOOT
3187format!) to the "bootm" command:
3188
3189	=> imi 40100000 40200000
3190
3191	## Checking Image at 40100000 ...
3192	   Image Name:	 2.2.13 for initrd on TQM850L
3193	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3194	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3195	   Load Address: 00000000
3196	   Entry Point:	 0000000c
3197	   Verifying Checksum ... OK
3198
3199	## Checking Image at 40200000 ...
3200	   Image Name:	 Simple Ramdisk Image
3201	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3202	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3203	   Load Address: 00000000
3204	   Entry Point:	 00000000
3205	   Verifying Checksum ... OK
3206
3207	=> bootm 40100000 40200000
3208	## Booting Linux kernel at 40100000 ...
3209	   Image Name:	 2.2.13 for initrd on TQM850L
3210	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3211	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3212	   Load Address: 00000000
3213	   Entry Point:	 0000000c
3214	   Verifying Checksum ... OK
3215	   Uncompressing Kernel Image ... OK
3216	## Loading RAMDisk Image at 40200000 ...
3217	   Image Name:	 Simple Ramdisk Image
3218	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3219	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3220	   Load Address: 00000000
3221	   Entry Point:	 00000000
3222	   Verifying Checksum ... OK
3223	   Loading Ramdisk ... OK
3224	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
3225	Boot arguments: root=/dev/ram
3226	time_init: decrementer frequency = 187500000/60
3227	Calibrating delay loop... 49.77 BogoMIPS
3228	...
3229	RAMDISK: Compressed image found at block 0
3230	VFS: Mounted root (ext2 filesystem).
3231
3232	bash#
3233
3234Boot Linux and pass a flat device tree:
3235-----------
3236
3237First, U-Boot must be compiled with the appropriate defines. See the section
3238titled "Linux Kernel Interface" above for a more in depth explanation. The
3239following is an example of how to start a kernel and pass an updated
3240flat device tree:
3241
3242=> print oftaddr
3243oftaddr=0x300000
3244=> print oft
3245oft=oftrees/mpc8540ads.dtb
3246=> tftp $oftaddr $oft
3247Speed: 1000, full duplex
3248Using TSEC0 device
3249TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3250Filename 'oftrees/mpc8540ads.dtb'.
3251Load address: 0x300000
3252Loading: #
3253done
3254Bytes transferred = 4106 (100a hex)
3255=> tftp $loadaddr $bootfile
3256Speed: 1000, full duplex
3257Using TSEC0 device
3258TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3259Filename 'uImage'.
3260Load address: 0x200000
3261Loading:############
3262done
3263Bytes transferred = 1029407 (fb51f hex)
3264=> print loadaddr
3265loadaddr=200000
3266=> print oftaddr
3267oftaddr=0x300000
3268=> bootm $loadaddr - $oftaddr
3269## Booting image at 00200000 ...
3270   Image Name:	 Linux-2.6.17-dirty
3271   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3272   Data Size:	 1029343 Bytes = 1005.2 kB
3273   Load Address: 00000000
3274   Entry Point:	 00000000
3275   Verifying Checksum ... OK
3276   Uncompressing Kernel Image ... OK
3277Booting using flat device tree at 0x300000
3278Using MPC85xx ADS machine description
3279Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3280[snip]
3281
3282
3283More About U-Boot Image Types:
3284------------------------------
3285
3286U-Boot supports the following image types:
3287
3288   "Standalone Programs" are directly runnable in the environment
3289	provided by U-Boot; it is expected that (if they behave
3290	well) you can continue to work in U-Boot after return from
3291	the Standalone Program.
3292   "OS Kernel Images" are usually images of some Embedded OS which
3293	will take over control completely. Usually these programs
3294	will install their own set of exception handlers, device
3295	drivers, set up the MMU, etc. - this means, that you cannot
3296	expect to re-enter U-Boot except by resetting the CPU.
3297   "RAMDisk Images" are more or less just data blocks, and their
3298	parameters (address, size) are passed to an OS kernel that is
3299	being started.
3300   "Multi-File Images" contain several images, typically an OS
3301	(Linux) kernel image and one or more data images like
3302	RAMDisks. This construct is useful for instance when you want
3303	to boot over the network using BOOTP etc., where the boot
3304	server provides just a single image file, but you want to get
3305	for instance an OS kernel and a RAMDisk image.
3306
3307	"Multi-File Images" start with a list of image sizes, each
3308	image size (in bytes) specified by an "uint32_t" in network
3309	byte order. This list is terminated by an "(uint32_t)0".
3310	Immediately after the terminating 0 follow the images, one by
3311	one, all aligned on "uint32_t" boundaries (size rounded up to
3312	a multiple of 4 bytes).
3313
3314   "Firmware Images" are binary images containing firmware (like
3315	U-Boot or FPGA images) which usually will be programmed to
3316	flash memory.
3317
3318   "Script files" are command sequences that will be executed by
3319	U-Boot's command interpreter; this feature is especially
3320	useful when you configure U-Boot to use a real shell (hush)
3321	as command interpreter.
3322
3323
3324Standalone HOWTO:
3325=================
3326
3327One of the features of U-Boot is that you can dynamically load and
3328run "standalone" applications, which can use some resources of
3329U-Boot like console I/O functions or interrupt services.
3330
3331Two simple examples are included with the sources:
3332
3333"Hello World" Demo:
3334-------------------
3335
3336'examples/hello_world.c' contains a small "Hello World" Demo
3337application; it is automatically compiled when you build U-Boot.
3338It's configured to run at address 0x00040004, so you can play with it
3339like that:
3340
3341	=> loads
3342	## Ready for S-Record download ...
3343	~>examples/hello_world.srec
3344	1 2 3 4 5 6 7 8 9 10 11 ...
3345	[file transfer complete]
3346	[connected]
3347	## Start Addr = 0x00040004
3348
3349	=> go 40004 Hello World! This is a test.
3350	## Starting application at 0x00040004 ...
3351	Hello World
3352	argc = 7
3353	argv[0] = "40004"
3354	argv[1] = "Hello"
3355	argv[2] = "World!"
3356	argv[3] = "This"
3357	argv[4] = "is"
3358	argv[5] = "a"
3359	argv[6] = "test."
3360	argv[7] = "<NULL>"
3361	Hit any key to exit ...
3362
3363	## Application terminated, rc = 0x0
3364
3365Another example, which demonstrates how to register a CPM interrupt
3366handler with the U-Boot code, can be found in 'examples/timer.c'.
3367Here, a CPM timer is set up to generate an interrupt every second.
3368The interrupt service routine is trivial, just printing a '.'
3369character, but this is just a demo program. The application can be
3370controlled by the following keys:
3371
3372	? - print current values og the CPM Timer registers
3373	b - enable interrupts and start timer
3374	e - stop timer and disable interrupts
3375	q - quit application
3376
3377	=> loads
3378	## Ready for S-Record download ...
3379	~>examples/timer.srec
3380	1 2 3 4 5 6 7 8 9 10 11 ...
3381	[file transfer complete]
3382	[connected]
3383	## Start Addr = 0x00040004
3384
3385	=> go 40004
3386	## Starting application at 0x00040004 ...
3387	TIMERS=0xfff00980
3388	Using timer 1
3389	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3390
3391Hit 'b':
3392	[q, b, e, ?] Set interval 1000000 us
3393	Enabling timer
3394Hit '?':
3395	[q, b, e, ?] ........
3396	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3397Hit '?':
3398	[q, b, e, ?] .
3399	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3400Hit '?':
3401	[q, b, e, ?] .
3402	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3403Hit '?':
3404	[q, b, e, ?] .
3405	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3406Hit 'e':
3407	[q, b, e, ?] ...Stopping timer
3408Hit 'q':
3409	[q, b, e, ?] ## Application terminated, rc = 0x0
3410
3411
3412Minicom warning:
3413================
3414
3415Over time, many people have reported problems when trying to use the
3416"minicom" terminal emulation program for serial download. I (wd)
3417consider minicom to be broken, and recommend not to use it. Under
3418Unix, I recommend to use C-Kermit for general purpose use (and
3419especially for kermit binary protocol download ("loadb" command), and
3420use "cu" for S-Record download ("loads" command).
3421
3422Nevertheless, if you absolutely want to use it try adding this
3423configuration to your "File transfer protocols" section:
3424
3425	   Name	   Program			Name U/D FullScr IO-Red. Multi
3426	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
3427	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
3428
3429
3430NetBSD Notes:
3431=============
3432
3433Starting at version 0.9.2, U-Boot supports NetBSD both as host
3434(build U-Boot) and target system (boots NetBSD/mpc8xx).
3435
3436Building requires a cross environment; it is known to work on
3437NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3438need gmake since the Makefiles are not compatible with BSD make).
3439Note that the cross-powerpc package does not install include files;
3440attempting to build U-Boot will fail because <machine/ansi.h> is
3441missing.  This file has to be installed and patched manually:
3442
3443	# cd /usr/pkg/cross/powerpc-netbsd/include
3444	# mkdir powerpc
3445	# ln -s powerpc machine
3446	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3447	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
3448
3449Native builds *don't* work due to incompatibilities between native
3450and U-Boot include files.
3451
3452Booting assumes that (the first part of) the image booted is a
3453stage-2 loader which in turn loads and then invokes the kernel
3454proper. Loader sources will eventually appear in the NetBSD source
3455tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3456meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3457
3458
3459Implementation Internals:
3460=========================
3461
3462The following is not intended to be a complete description of every
3463implementation detail. However, it should help to understand the
3464inner workings of U-Boot and make it easier to port it to custom
3465hardware.
3466
3467
3468Initial Stack, Global Data:
3469---------------------------
3470
3471The implementation of U-Boot is complicated by the fact that U-Boot
3472starts running out of ROM (flash memory), usually without access to
3473system RAM (because the memory controller is not initialized yet).
3474This means that we don't have writable Data or BSS segments, and BSS
3475is not initialized as zero. To be able to get a C environment working
3476at all, we have to allocate at least a minimal stack. Implementation
3477options for this are defined and restricted by the CPU used: Some CPU
3478models provide on-chip memory (like the IMMR area on MPC8xx and
3479MPC826x processors), on others (parts of) the data cache can be
3480locked as (mis-) used as memory, etc.
3481
3482	Chris Hallinan posted a good summary of	 these	issues	to  the
3483	u-boot-users mailing list:
3484
3485	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3486	From: "Chris Hallinan" <clh@net1plus.com>
3487	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3488	...
3489
3490	Correct me if I'm wrong, folks, but the way I understand it
3491	is this: Using DCACHE as initial RAM for Stack, etc, does not
3492	require any physical RAM backing up the cache. The cleverness
3493	is that the cache is being used as a temporary supply of
3494	necessary storage before the SDRAM controller is setup. It's
3495	beyond the scope of this list to expain the details, but you
3496	can see how this works by studying the cache architecture and
3497	operation in the architecture and processor-specific manuals.
3498
3499	OCM is On Chip Memory, which I believe the 405GP has 4K. It
3500	is another option for the system designer to use as an
3501	initial stack/ram area prior to SDRAM being available. Either
3502	option should work for you. Using CS 4 should be fine if your
3503	board designers haven't used it for something that would
3504	cause you grief during the initial boot! It is frequently not
3505	used.
3506
3507	CFG_INIT_RAM_ADDR should be somewhere that won't interfere
3508	with your processor/board/system design. The default value
3509	you will find in any recent u-boot distribution in
3510	walnut.h should work for you. I'd set it to a value larger
3511	than your SDRAM module. If you have a 64MB SDRAM module, set
3512	it above 400_0000. Just make sure your board has no resources
3513	that are supposed to respond to that address! That code in
3514	start.S has been around a while and should work as is when
3515	you get the config right.
3516
3517	-Chris Hallinan
3518	DS4.COM, Inc.
3519
3520It is essential to remember this, since it has some impact on the C
3521code for the initialization procedures:
3522
3523* Initialized global data (data segment) is read-only. Do not attempt
3524  to write it.
3525
3526* Do not use any unitialized global data (or implicitely initialized
3527  as zero data - BSS segment) at all - this is undefined, initiali-
3528  zation is performed later (when relocating to RAM).
3529
3530* Stack space is very limited. Avoid big data buffers or things like
3531  that.
3532
3533Having only the stack as writable memory limits means we cannot use
3534normal global data to share information beween the code. But it
3535turned out that the implementation of U-Boot can be greatly
3536simplified by making a global data structure (gd_t) available to all
3537functions. We could pass a pointer to this data as argument to _all_
3538functions, but this would bloat the code. Instead we use a feature of
3539the GCC compiler (Global Register Variables) to share the data: we
3540place a pointer (gd) to the global data into a register which we
3541reserve for this purpose.
3542
3543When choosing a register for such a purpose we are restricted by the
3544relevant  (E)ABI  specifications for the current architecture, and by
3545GCC's implementation.
3546
3547For PowerPC, the following registers have specific use:
3548	R1:	stack pointer
3549	R2:	TOC pointer
3550	R3-R4:	parameter passing and return values
3551	R5-R10: parameter passing
3552	R13:	small data area pointer
3553	R30:	GOT pointer
3554	R31:	frame pointer
3555
3556	(U-Boot also uses R14 as internal GOT pointer.)
3557
3558    ==> U-Boot will use R29 to hold a pointer to the global data
3559
3560    Note: on PPC, we could use a static initializer (since the
3561    address of the global data structure is known at compile time),
3562    but it turned out that reserving a register results in somewhat
3563    smaller code - although the code savings are not that big (on
3564    average for all boards 752 bytes for the whole U-Boot image,
3565    624 text + 127 data).
3566
3567On ARM, the following registers are used:
3568
3569	R0:	function argument word/integer result
3570	R1-R3:	function argument word
3571	R9:	GOT pointer
3572	R10:	stack limit (used only if stack checking if enabled)
3573	R11:	argument (frame) pointer
3574	R12:	temporary workspace
3575	R13:	stack pointer
3576	R14:	link register
3577	R15:	program counter
3578
3579    ==> U-Boot will use R8 to hold a pointer to the global data
3580
3581NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3582or current versions of GCC may "optimize" the code too much.
3583
3584Memory Management:
3585------------------
3586
3587U-Boot runs in system state and uses physical addresses, i.e. the
3588MMU is not used either for address mapping nor for memory protection.
3589
3590The available memory is mapped to fixed addresses using the memory
3591controller. In this process, a contiguous block is formed for each
3592memory type (Flash, SDRAM, SRAM), even when it consists of several
3593physical memory banks.
3594
3595U-Boot is installed in the first 128 kB of the first Flash bank (on
3596TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3597booting and sizing and initializing DRAM, the code relocates itself
3598to the upper end of DRAM. Immediately below the U-Boot code some
3599memory is reserved for use by malloc() [see CFG_MALLOC_LEN
3600configuration setting]. Below that, a structure with global Board
3601Info data is placed, followed by the stack (growing downward).
3602
3603Additionally, some exception handler code is copied to the low 8 kB
3604of DRAM (0x00000000 ... 0x00001FFF).
3605
3606So a typical memory configuration with 16 MB of DRAM could look like
3607this:
3608
3609	0x0000 0000	Exception Vector code
3610	      :
3611	0x0000 1FFF
3612	0x0000 2000	Free for Application Use
3613	      :
3614	      :
3615
3616	      :
3617	      :
3618	0x00FB FF20	Monitor Stack (Growing downward)
3619	0x00FB FFAC	Board Info Data and permanent copy of global data
3620	0x00FC 0000	Malloc Arena
3621	      :
3622	0x00FD FFFF
3623	0x00FE 0000	RAM Copy of Monitor Code
3624	...		eventually: LCD or video framebuffer
3625	...		eventually: pRAM (Protected RAM - unchanged by reset)
3626	0x00FF FFFF	[End of RAM]
3627
3628
3629System Initialization:
3630----------------------
3631
3632In the reset configuration, U-Boot starts at the reset entry point
3633(on most PowerPC systens at address 0x00000100). Because of the reset
3634configuration for CS0# this is a mirror of the onboard Flash memory.
3635To be able to re-map memory U-Boot then jumps to its link address.
3636To be able to implement the initialization code in C, a (small!)
3637initial stack is set up in the internal Dual Ported RAM (in case CPUs
3638which provide such a feature like MPC8xx or MPC8260), or in a locked
3639part of the data cache. After that, U-Boot initializes the CPU core,
3640the caches and the SIU.
3641
3642Next, all (potentially) available memory banks are mapped using a
3643preliminary mapping. For example, we put them on 512 MB boundaries
3644(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3645on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3646programmed for SDRAM access. Using the temporary configuration, a
3647simple memory test is run that determines the size of the SDRAM
3648banks.
3649
3650When there is more than one SDRAM bank, and the banks are of
3651different size, the largest is mapped first. For equal size, the first
3652bank (CS2#) is mapped first. The first mapping is always for address
36530x00000000, with any additional banks following immediately to create
3654contiguous memory starting from 0.
3655
3656Then, the monitor installs itself at the upper end of the SDRAM area
3657and allocates memory for use by malloc() and for the global Board
3658Info data; also, the exception vector code is copied to the low RAM
3659pages, and the final stack is set up.
3660
3661Only after this relocation will you have a "normal" C environment;
3662until that you are restricted in several ways, mostly because you are
3663running from ROM, and because the code will have to be relocated to a
3664new address in RAM.
3665
3666
3667U-Boot Porting Guide:
3668----------------------
3669
3670[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3671list, October 2002]
3672
3673
3674int main (int argc, char *argv[])
3675{
3676	sighandler_t no_more_time;
3677
3678	signal (SIGALRM, no_more_time);
3679	alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
3680
3681	if (available_money > available_manpower) {
3682		pay consultant to port U-Boot;
3683		return 0;
3684	}
3685
3686	Download latest U-Boot source;
3687
3688	Subscribe to u-boot-users mailing list;
3689
3690	if (clueless) {
3691		email ("Hi, I am new to U-Boot, how do I get started?");
3692	}
3693
3694	while (learning) {
3695		Read the README file in the top level directory;
3696		Read http://www.denx.de/twiki/bin/view/DULG/Manual ;
3697		Read the source, Luke;
3698	}
3699
3700	if (available_money > toLocalCurrency ($2500)) {
3701		Buy a BDI2000;
3702	} else {
3703		Add a lot of aggravation and time;
3704	}
3705
3706	Create your own board support subdirectory;
3707
3708	Create your own board config file;
3709
3710	while (!running) {
3711		do {
3712			Add / modify source code;
3713		} until (compiles);
3714		Debug;
3715		if (clueless)
3716			email ("Hi, I am having problems...");
3717	}
3718	Send patch file to Wolfgang;
3719
3720	return 0;
3721}
3722
3723void no_more_time (int sig)
3724{
3725      hire_a_guru();
3726}
3727
3728
3729Coding Standards:
3730-----------------
3731
3732All contributions to U-Boot should conform to the Linux kernel
3733coding style; see the file "Documentation/CodingStyle" and the script
3734"scripts/Lindent" in your Linux kernel source directory.  In sources
3735originating from U-Boot a style corresponding to "Lindent -pcs" (adding
3736spaces before parameters to function calls) is actually used.
3737
3738Source files originating from a different project (for example the
3739MTD subsystem) are generally exempt from these guidelines and are not
3740reformated to ease subsequent migration to newer versions of those
3741sources.
3742
3743Please note that U-Boot is implemented in C (and to some small parts in
3744Assembler); no C++ is used, so please do not use C++ style comments (//)
3745in your code.
3746
3747Please also stick to the following formatting rules:
3748- remove any trailing white space
3749- use TAB characters for indentation, not spaces
3750- make sure NOT to use DOS '\r\n' line feeds
3751- do not add more than 2 empty lines to source files
3752- do not add trailing empty lines to source files
3753
3754Submissions which do not conform to the standards may be returned
3755with a request to reformat the changes.
3756
3757
3758Submitting Patches:
3759-------------------
3760
3761Since the number of patches for U-Boot is growing, we need to
3762establish some rules. Submissions which do not conform to these rules
3763may be rejected, even when they contain important and valuable stuff.
3764
3765Patches shall be sent to the u-boot-users mailing list.
3766
3767When you send a patch, please include the following information with
3768it:
3769
3770* For bug fixes: a description of the bug and how your patch fixes
3771  this bug. Please try to include a way of demonstrating that the
3772  patch actually fixes something.
3773
3774* For new features: a description of the feature and your
3775  implementation.
3776
3777* A CHANGELOG entry as plaintext (separate from the patch)
3778
3779* For major contributions, your entry to the CREDITS file
3780
3781* When you add support for a new board, don't forget to add this
3782  board to the MAKEALL script, too.
3783
3784* If your patch adds new configuration options, don't forget to
3785  document these in the README file.
3786
3787* The patch itself. If you are accessing the CVS repository use "cvs
3788  update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
3789  version of diff does not support these options, then get the latest
3790  version of GNU diff.
3791
3792  The current directory when running this command shall be the top
3793  level directory of the U-Boot source tree, or it's parent directory
3794  (i. e. please make sure that your patch includes sufficient
3795  directory information for the affected files).
3796
3797  We accept patches as plain text, MIME attachments or as uuencoded
3798  gzipped text.
3799
3800* If one logical set of modifications affects or creates several
3801  files, all these changes shall be submitted in a SINGLE patch file.
3802
3803* Changesets that contain different, unrelated modifications shall be
3804  submitted as SEPARATE patches, one patch per changeset.
3805
3806
3807Notes:
3808
3809* Before sending the patch, run the MAKEALL script on your patched
3810  source tree and make sure that no errors or warnings are reported
3811  for any of the boards.
3812
3813* Keep your modifications to the necessary minimum: A patch
3814  containing several unrelated changes or arbitrary reformats will be
3815  returned with a request to re-formatting / split it.
3816
3817* If you modify existing code, make sure that your new code does not
3818  add to the memory footprint of the code ;-) Small is beautiful!
3819  When adding new features, these should compile conditionally only
3820  (using #ifdef), and the resulting code with the new feature
3821  disabled must not need more memory than the old code without your
3822  modification.
3823
3824* Remember that there is a size limit of 40 kB per message on the
3825  u-boot-users mailing list. Compression may help.
3826