xref: /rk3399_rockchip-uboot/README (revision b13fb01a62708492cae4b33c4d6fa9ae127905f4)
1#
2# (C) Copyright 2000 - 2002
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 and ARM processors, which can be
29installed in a boot ROM and used to initialize and test the hardware
30or to download and run application code.
31
32The development of U-Boot is closely related to Linux: some parts of
33the source code originate in the Linux source tree, we have some
34header files in common, and special provision has been made to
35support booting of Linux images.
36
37Some attention has been paid to make this software easily
38configurable and extendable. For instance, all monitor commands are
39implemented with the same call interface, so that it's very easy to
40add new commands. Also, instead of permanently adding rarely used
41code (for instance hardware test utilities) to the monitor, you can
42load and run it dynamically.
43
44
45Status:
46=======
47
48In general, all boards for which a configuration option exists in the
49Makefile have been tested to some extent and can be considered
50"working". In fact, many of them are used in production systems.
51
52In case of problems see the CHANGELOG and CREDITS files to find out
53who contributed the specific port.
54
55
56Where to get help:
57==================
58
59In case you have questions about, problems with or contributions for
60U-Boot you should send a message to the U-Boot mailing list at
61<u-boot-users@lists.sourceforge.net>. There is also an archive of
62previous traffic on the mailing list - please search the archive
63before asking FAQ's. Please see
64http://lists.sourceforge.net/lists/listinfo/u-boot-users/
65
66
67Where we come from:
68===================
69
70- start from 8xxrom sources
71- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
72- clean up code
73- make it easier to add custom boards
74- make it possible to add other [PowerPC] CPUs
75- extend functions, especially:
76  * Provide extended interface to Linux boot loader
77  * S-Record download
78  * network boot
79  * PCMCIA / CompactFLash / ATA disk / SCSI ... boot
80- create ARMBoot project (http://sourceforge.net/projects/armboot)
81- add other CPU families (starting with ARM)
82- create U-Boot project (http://sourceforge.net/projects/u-boot)
83
84
85Names and Spelling:
86===================
87
88The "official" name of this project is "Das U-Boot". The spelling
89"U-Boot" shall be used in all written text (documentation, comments
90in source files etc.). Example:
91
92	This is the README file for the U-Boot project.
93
94File names etc. shall be based on the string "u-boot". Examples:
95
96	include/asm-ppc/u-boot.h
97
98	#include <asm/u-boot.h>
99
100Variable names, preprocessor constants etc. shall be either based on
101the string "u_boot" or on "U_BOOT". Example:
102
103	U_BOOT_VERSION		u_boot_logo
104	IH_OS_U_BOOT		u_boot_hush_start
105
106
107Versioning:
108===========
109
110U-Boot uses a 3 level version number containing a version, a
111sub-version, and a patchlevel: "U-Boot-2.34.5" means version "2",
112sub-version "34", and patchlevel "4".
113
114The patchlevel is used to indicate certain stages of development
115between released versions, i. e. officially released versions of
116U-Boot will always have a patchlevel of "0".
117
118
119Directory Hierarchy:
120====================
121
122- board		Board dependent files
123- common	Misc architecture independent functions
124- cpu		CPU specific files
125- disk		Code for disk drive partition handling
126- doc		Documentation (don't expect too much)
127- drivers	Commonly used device drivers
128- dtt		Digital Thermometer and Thermostat drivers
129- examples	Example code for standalone applications, etc.
130- include	Header Files
131- disk		Harddisk interface code
132- net		Networking code
133- ppc		Files generic to PowerPC architecture
134- post		Power On Self Test
135- post/arch		Symlink to architecture specific Power On Self Test
136- post/arch-ppc		PowerPC architecture specific Power On Self Test
137- post/cpu/mpc8260	MPC8260 CPU specific Power On Self Test
138- post/cpu/mpc8xx	MPC8xx CPU specific Power On Self Test
139- rtc		Real Time Clock drivers
140- tools		Tools to build S-Record or U-Boot images, etc.
141
142- cpu/74xx_7xx	Files specific to Motorola MPC74xx and 7xx CPUs
143- cpu/arm925t	Files specific to ARM	   925	   CPUs
144- cpu/arm926ejs	Files specific to ARM	926	CPUs
145- cpu/mpc5xx	Files specific to Motorola MPC5xx  CPUs
146- cpu/mpc8xx	Files specific to Motorola MPC8xx  CPUs
147- cpu/mpc824x	Files specific to Motorola MPC824x CPUs
148- cpu/mpc8260	Files specific to Motorola MPC8260 CPU
149- cpu/mpc85xx	Files specific to Motorola MPC85xx CPUs
150- cpu/ppc4xx	Files specific to IBM	   4xx	   CPUs
151
152
153- board/LEOX/   Files specific to boards manufactured by The LEOX team
154- board/LEOX/elpt860	Files specific to ELPT860 boards
155- board/RPXClassic
156		Files specific to RPXClassic boards
157- board/RPXlite	Files specific to RPXlite    boards
158- board/at91rm9200dk Files specific to AT91RM9200DK boards
159- board/c2mon	Files specific to c2mon	     boards
160- board/cmi	Files specific to cmi        boards
161- board/cogent	Files specific to Cogent     boards
162		(need further configuration)
163		Files specific to CPCIISER4  boards
164- board/cpu86	Files specific to CPU86      boards
165- board/cray/	Files specific to boards manufactured by Cray
166- board/cray/L1		Files specific to L1         boards
167- board/cu824	Files specific to CU824	     boards
168- board/ebony   Files specific to IBM Ebony board
169- board/eric	Files specific to ERIC	     boards
170- board/esd/	Files specific to boards manufactured by ESD
171- board/esd/adciop	Files specific to ADCIOP     boards
172- board/esd/ar405	Files specific to AR405	     boards
173- board/esd/canbt	Files specific to CANBT	     boards
174- board/esd/cpci405	Files specific to CPCI405    boards
175- board/esd/cpciiser4	Files specific to CPCIISER4  boards
176- board/esd/common	Common files for ESD boards
177- board/esd/dasa_sim	Files specific to DASA_SIM   boards
178- board/esd/du405	Files specific to DU405      boards
179- board/esd/ocrtc	Files specific to OCRTC      boards
180- board/esd/pci405	Files specific to PCI405     boards
181- board/esteem192e
182		Files specific to ESTEEM192E boards
183- board/etx094	Files specific to ETX_094    boards
184- board/evb64260
185		Files specific to EVB64260   boards
186- board/fads	Files specific to FADS	     boards
187- board/flagadm Files specific to FLAGADM    boards
188- board/gen860t Files specific to GEN860T and GEN860T_SC    boards
189- board/genietv Files specific to GENIETV    boards
190- board/gth	Files specific to GTH	     boards
191- board/hermes	Files specific to HERMES     boards
192- board/hymod	Files specific to HYMOD	     boards
193- board/icu862	Files specific to ICU862     boards
194- board/ip860	Files specific to IP860	     boards
195- board/iphase4539
196		Files specific to Interphase4539 boards
197- board/ivm	Files specific to IVMS8/IVML24 boards
198- board/lantec	Files specific to LANTEC     boards
199- board/lwmon	Files specific to LWMON	     boards
200- board/mbx8xx	Files specific to MBX	     boards
201- board/mpc8260ads
202		Files specific to MPC8260ADS and PQ2FADS-ZU boards
203- board/mpc8540ads
204		Files specific to MPC8540ADS boards
205- board/mpc8560ads
206		Files specific to MPC8560ADS boards
207- board/mpl/	Files specific to boards manufactured by MPL
208- board/mpl/common	Common files for MPL boards
209- board/mpl/pip405	Files specific to PIP405     boards
210- board/mpl/mip405	Files specific to MIP405     boards
211- board/mpl/vcma9	Files specific to VCMA9      boards
212- board/musenki	Files specific to MUSEKNI    boards
213- board/mvs1	Files specific to MVS1       boards
214- board/nx823   Files specific to NX823      boards
215- board/oxc	Files specific to OXC        boards
216- board/omap1510inn
217		Files specific to OMAP 1510 Innovator boards
218- board/omap1610inn
219		Files specific to OMAP 1610 Innovator boards
220- board/pcippc2	Files specific to PCIPPC2/PCIPPC6 boards
221- board/pm826	Files specific to PM826      boards
222- board/ppmc8260
223		Files specific to PPMC8260   boards
224- board/rpxsuper
225		Files specific to RPXsuper   boards
226- board/rsdproto
227		Files specific to RSDproto   boards
228- board/sandpoint
229		Files specific to Sandpoint  boards
230- board/sbc8260	Files specific to SBC8260    boards
231- board/sacsng	Files specific to SACSng     boards
232- board/siemens Files specific to boards manufactured by Siemens AG
233- board/siemens/CCM	Files specific to CCM	     boards
234- board/siemens/IAD210	Files specific to IAD210     boards
235- board/siemens/SCM	Files specific to SCM        boards
236- board/siemens/pcu_e	Files specific to PCU_E	     boards
237- board/sixnet	Files specific to SIXNET     boards
238- board/spd8xx	Files specific to SPD8xxTS   boards
239- board/tqm8260 Files specific to TQM8260    boards
240- board/tqm8xx	Files specific to TQM8xxL    boards
241- board/w7o	Files specific to W7O        boards
242- board/walnut405
243		Files specific to Walnut405  boards
244- board/westel/	Files specific to boards manufactured by Westel Wireless
245- board/westel/amx860	Files specific to AMX860     boards
246- board/utx8245	Files specific to UTX8245   boards
247- board/zpc1900	Files specific to Zephyr Engineering ZPC.1900 board
248
249Software Configuration:
250=======================
251
252Configuration is usually done using C preprocessor defines; the
253rationale behind that is to avoid dead code whenever possible.
254
255There are two classes of configuration variables:
256
257* Configuration _OPTIONS_:
258  These are selectable by the user and have names beginning with
259  "CONFIG_".
260
261* Configuration _SETTINGS_:
262  These depend on the hardware etc. and should not be meddled with if
263  you don't know what you're doing; they have names beginning with
264  "CFG_".
265
266Later we will add a configuration tool - probably similar to or even
267identical to what's used for the Linux kernel. Right now, we have to
268do the configuration by hand, which means creating some symbolic
269links and editing some configuration files. We use the TQM8xxL boards
270as an example here.
271
272
273Selection of Processor Architecture and Board Type:
274---------------------------------------------------
275
276For all supported boards there are ready-to-use default
277configurations available; just type "make <board_name>_config".
278
279Example: For a TQM823L module type:
280
281	cd u-boot
282	make TQM823L_config
283
284For the Cogent platform, you need to specify the cpu type as well;
285e.g. "make cogent_mpc8xx_config". And also configure the cogent
286directory according to the instructions in cogent/README.
287
288
289Configuration Options:
290----------------------
291
292Configuration depends on the combination of board and CPU type; all
293such information is kept in a configuration file
294"include/configs/<board_name>.h".
295
296Example: For a TQM823L module, all configuration settings are in
297"include/configs/TQM823L.h".
298
299
300Many of the options are named exactly as the corresponding Linux
301kernel configuration options. The intention is to make it easier to
302build a config tool - later.
303
304
305The following options need to be configured:
306
307- CPU Type:	Define exactly one of
308
309		PowerPC based CPUs:
310		-------------------
311		CONFIG_MPC823,	CONFIG_MPC850,	CONFIG_MPC855,	CONFIG_MPC860
312	or	CONFIG_MPC5xx
313	or	CONFIG_MPC824X, CONFIG_MPC8260
314	or	CONFIG_MPC85xx
315	or	CONFIG_IOP480
316	or	CONFIG_405GP
317	or	CONFIG_405EP
318	or	CONFIG_440
319	or	CONFIG_MPC74xx
320	or	CONFIG_750FX
321
322		ARM based CPUs:
323		---------------
324		CONFIG_SA1110
325		CONFIG_ARM7
326		CONFIG_PXA250
327
328
329- Board Type:	Define exactly one of
330
331		PowerPC based boards:
332		---------------------
333
334		CONFIG_ADCIOP,     CONFIG_ICU862      CONFIG_RPXsuper,
335		CONFIG_ADS860,     CONFIG_IP860,      CONFIG_SM850,
336		CONFIG_AMX860,     CONFIG_IPHASE4539, CONFIG_SPD823TS,
337		CONFIG_AR405,      CONFIG_IVML24,     CONFIG_SXNI855T,
338		CONFIG_BAB7xx,     CONFIG_IVML24_128, CONFIG_Sandpoint8240,
339		CONFIG_CANBT,      CONFIG_IVML24_256, CONFIG_Sandpoint8245,
340		CONFIG_CCM,        CONFIG_IVMS8,      CONFIG_TQM823L,
341		CONFIG_CPCI405,    CONFIG_IVMS8_128,  CONFIG_TQM850L,
342		CONFIG_CPCI4052,   CONFIG_IVMS8_256,  CONFIG_TQM855L,
343		CONFIG_CPCIISER4,  CONFIG_LANTEC,     CONFIG_TQM860L,
344		CONFIG_CPU86,      CONFIG_MBX,        CONFIG_TQM8260,
345		CONFIG_CRAYL1,     CONFIG_MBX860T,    CONFIG_TTTech,
346		CONFIG_CU824,      CONFIG_MHPC,       CONFIG_UTX8245,
347		CONFIG_DASA_SIM,   CONFIG_MIP405,     CONFIG_W7OLMC,
348		CONFIG_DU405,      CONFIG_MOUSSE,     CONFIG_W7OLMG,
349		CONFIG_ELPPC,      CONFIG_MPC8260ADS, CONFIG_WALNUT405,
350		CONFIG_ERIC,       CONFIG_MUSENKI,    CONFIG_ZUMA,
351		CONFIG_ESTEEM192E, CONFIG_MVS1,       CONFIG_c2mon,
352		CONFIG_ETX094,     CONFIG_NX823,      CONFIG_cogent_mpc8260,
353		CONFIG_EVB64260,   CONFIG_OCRTC,      CONFIG_cogent_mpc8xx,
354		CONFIG_FADS823,    CONFIG_ORSG,       CONFIG_ep8260,
355		CONFIG_FADS850SAR, CONFIG_OXC,        CONFIG_gw8260,
356		CONFIG_FADS860T,   CONFIG_PCI405,     CONFIG_hermes,
357		CONFIG_FLAGADM,    CONFIG_PCIPPC2,    CONFIG_hymod,
358		CONFIG_FPS850L,    CONFIG_PCIPPC6,    CONFIG_lwmon,
359		CONFIG_GEN860T,    CONFIG_PIP405,     CONFIG_pcu_e,
360		CONFIG_GENIETV,    CONFIG_PM826,      CONFIG_ppmc8260,
361		CONFIG_GTH,        CONFIG_RPXClassic, CONFIG_rsdproto,
362		CONFIG_IAD210,     CONFIG_RPXlite,    CONFIG_sbc8260,
363		CONFIG_EBONY,      CONFIG_sacsng,     CONFIG_FPS860L,
364		CONFIG_V37,        CONFIG_ELPT860,    CONFIG_CMI,
365		CONFIG_NETVIA,     CONFIG_RBC823,     CONFIG_ZPC1900,
366		CONFIG_MPC8540ADS, CONFIG_MPC8560ADS
367
368		ARM based boards:
369		-----------------
370
371		CONFIG_HHP_CRADLE,  CONFIG_DNP1110,    CONFIG_EP7312,
372		CONFIG_IMPA7,       CONFIG_LART,       CONFIG_LUBBOCK,
373		CONFIG_INNOVATOROMAP1510,	CONFIG_INNOVATOROMAP1610
374		CONFIG_SHANNON,     CONFIG_SMDK2400,   CONFIG_SMDK2410,
375		CONFIG_TRAB,	    CONFIG_VCMA9,      CONFIG_AT91RM9200DK
376
377
378- CPU Module Type: (if CONFIG_COGENT is defined)
379		Define exactly one of
380		CONFIG_CMA286_60_OLD
381--- FIXME --- not tested yet:
382		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
383		CONFIG_CMA287_23, CONFIG_CMA287_50
384
385- Motherboard Type: (if CONFIG_COGENT is defined)
386		Define exactly one of
387		CONFIG_CMA101, CONFIG_CMA102
388
389- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
390		Define one or more of
391		CONFIG_CMA302
392
393- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
394		Define one or more of
395		CONFIG_LCD_HEARTBEAT	- update a character position on
396					  the lcd display every second with
397					  a "rotator" |\-/|\-/
398
399- Board flavour: (if CONFIG_MPC8260ADS is defined)
400		CONFIG_ADSTYPE
401		Possible values are:
402			CFG_8260ADS	- original MPC8260ADS
403			CFG_8266ADS	- MPC8266ADS (untested)
404			CFG_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
405
406
407- MPC824X Family Member (if CONFIG_MPC824X is defined)
408		Define exactly one of
409		CONFIG_MPC8240, CONFIG_MPC8245
410
411- 8xx CPU Options: (if using an 8xx cpu)
412		Define one or more of
413		CONFIG_8xx_GCLK_FREQ	- if get_gclk_freq() cannot work
414					  e.g. if there is no 32KHz
415					  reference PIT/RTC clock
416
417- Linux Kernel Interface:
418		CONFIG_CLOCKS_IN_MHZ
419
420		U-Boot stores all clock information in Hz
421		internally. For binary compatibility with older Linux
422		kernels (which expect the clocks passed in the
423		bd_info data to be in MHz) the environment variable
424		"clocks_in_mhz" can be defined so that U-Boot
425		converts clock data to MHZ before passing it to the
426		Linux kernel.
427		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
428		"clocks_in_mhz=1" is  automatically  included  in  the
429		default environment.
430
431		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
432
433		When transfering memsize parameter to linux, some versions
434		expect it to be in bytes, others in MB.
435		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
436
437- Console Interface:
438		Depending on board, define exactly one serial port
439		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
440		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
441		console by defining CONFIG_8xx_CONS_NONE
442
443		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
444		port routines must be defined elsewhere
445		(i.e. serial_init(), serial_getc(), ...)
446
447		CONFIG_CFB_CONSOLE
448		Enables console device for a color framebuffer. Needs following
449		defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
450			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
451						(default big endian)
452			VIDEO_HW_RECTFILL	graphic chip supports
453						rectangle fill
454						(cf. smiLynxEM)
455			VIDEO_HW_BITBLT		graphic chip supports
456						bit-blit (cf. smiLynxEM)
457			VIDEO_VISIBLE_COLS	visible pixel columns
458						(cols=pitch)
459			VIDEO_VISIBLE_ROWS      visible pixel rows
460			VIDEO_PIXEL_SIZE        bytes per pixel
461			VIDEO_DATA_FORMAT	graphic data format
462						(0-5, cf. cfb_console.c)
463			VIDEO_FB_ADRS           framebuffer address
464			VIDEO_KBD_INIT_FCT	keyboard int fct
465						(i.e. i8042_kbd_init())
466			VIDEO_TSTC_FCT		test char fct
467						(i.e. i8042_tstc)
468			VIDEO_GETC_FCT		get char fct
469						(i.e. i8042_getc)
470			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
471						(requires blink timer
472						cf. i8042.c)
473			CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
474			CONFIG_CONSOLE_TIME	display time/date info in
475						upper right corner
476						(requires CFG_CMD_DATE)
477			CONFIG_VIDEO_LOGO	display Linux logo in
478						upper left corner
479			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
480						linux_logo.h for logo.
481						Requires CONFIG_VIDEO_LOGO
482			CONFIG_CONSOLE_EXTRA_INFO
483						addional board info beside
484						the logo
485
486		When CONFIG_CFB_CONSOLE is defined, video console is
487		default i/o. Serial console can be forced with
488		environment 'console=serial'.
489
490                When CONFIG_SILENT_CONSOLE is defined, all console
491                messages (by U-Boot and Linux!) can be silenced with
492                the "silent" environment variable. See
493                doc/README.silent for more information.
494
495- Console Baudrate:
496		CONFIG_BAUDRATE - in bps
497		Select one of the baudrates listed in
498		CFG_BAUDRATE_TABLE, see below.
499
500- Interrupt driven serial port input:
501		CONFIG_SERIAL_SOFTWARE_FIFO
502
503		PPC405GP only.
504		Use an interrupt handler for receiving data on the
505		serial port. It also enables using hardware handshake
506		(RTS/CTS) and UART's built-in FIFO. Set the number of
507		bytes the interrupt driven input buffer should have.
508
509		Set to 0 to disable this feature (this is the default).
510		This will also disable hardware handshake.
511
512- Console UART Number:
513		CONFIG_UART1_CONSOLE
514
515		IBM PPC4xx only.
516		If defined internal UART1 (and not UART0) is used
517		as default U-Boot console.
518
519- Boot Delay:	CONFIG_BOOTDELAY - in seconds
520		Delay before automatically booting the default image;
521		set to -1 to disable autoboot.
522
523		See doc/README.autoboot for these options that
524		work with CONFIG_BOOTDELAY. None are required.
525		CONFIG_BOOT_RETRY_TIME
526		CONFIG_BOOT_RETRY_MIN
527		CONFIG_AUTOBOOT_KEYED
528		CONFIG_AUTOBOOT_PROMPT
529		CONFIG_AUTOBOOT_DELAY_STR
530		CONFIG_AUTOBOOT_STOP_STR
531		CONFIG_AUTOBOOT_DELAY_STR2
532		CONFIG_AUTOBOOT_STOP_STR2
533		CONFIG_ZERO_BOOTDELAY_CHECK
534		CONFIG_RESET_TO_RETRY
535
536- Autoboot Command:
537		CONFIG_BOOTCOMMAND
538		Only needed when CONFIG_BOOTDELAY is enabled;
539		define a command string that is automatically executed
540		when no character is read on the console interface
541		within "Boot Delay" after reset.
542
543		CONFIG_BOOTARGS
544		This can be used to pass arguments to the bootm
545		command. The value of CONFIG_BOOTARGS goes into the
546		environment value "bootargs".
547
548		CONFIG_RAMBOOT and CONFIG_NFSBOOT
549		The value of these goes into the environment as
550		"ramboot" and "nfsboot" respectively, and can be used
551		as a convenience, when switching between booting from
552		ram and nfs.
553
554- Pre-Boot Commands:
555		CONFIG_PREBOOT
556
557		When this option is #defined, the existence of the
558		environment variable "preboot" will be checked
559		immediately before starting the CONFIG_BOOTDELAY
560		countdown and/or running the auto-boot command resp.
561		entering interactive mode.
562
563		This feature is especially useful when "preboot" is
564		automatically generated or modified. For an example
565		see the LWMON board specific code: here "preboot" is
566		modified when the user holds down a certain
567		combination of keys on the (special) keyboard when
568		booting the systems
569
570- Serial Download Echo Mode:
571		CONFIG_LOADS_ECHO
572		If defined to 1, all characters received during a
573		serial download (using the "loads" command) are
574		echoed back. This might be needed by some terminal
575		emulations (like "cu"), but may as well just take
576		time on others. This setting #define's the initial
577		value of the "loads_echo" environment variable.
578
579- Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined)
580		CONFIG_KGDB_BAUDRATE
581		Select one of the baudrates listed in
582		CFG_BAUDRATE_TABLE, see below.
583
584- Monitor Functions:
585		CONFIG_COMMANDS
586		Most monitor functions can be selected (or
587		de-selected) by adjusting the definition of
588		CONFIG_COMMANDS; to select individual functions,
589		#define CONFIG_COMMANDS by "OR"ing any of the
590		following values:
591
592		#define enables commands:
593		-------------------------
594		CFG_CMD_ASKENV	* ask for env variable
595		CFG_CMD_AUTOSCRIPT Autoscript Support
596		CFG_CMD_BDI	  bdinfo
597		CFG_CMD_BEDBUG	  Include BedBug Debugger
598		CFG_CMD_BMP     * BMP support
599		CFG_CMD_BOOTD	  bootd
600		CFG_CMD_CACHE	  icache, dcache
601		CFG_CMD_CONSOLE	  coninfo
602		CFG_CMD_DATE	* support for RTC, date/time...
603		CFG_CMD_DHCP	  DHCP support
604		CFG_CMD_DIAG    * Diagnostics
605		CFG_CMD_DOC     * Disk-On-Chip Support
606		CFG_CMD_DTT       Digital Therm and Thermostat
607		CFG_CMD_ECHO	* echo arguments
608		CFG_CMD_EEPROM	* EEPROM read/write support
609		CFG_CMD_ELF	  bootelf, bootvx
610		CFG_CMD_ENV	  saveenv
611		CFG_CMD_FDC	* Floppy Disk Support
612		CFG_CMD_FAT	  FAT partition support
613		CFG_CMD_FDOS	* Dos diskette Support
614		CFG_CMD_FLASH	  flinfo, erase, protect
615		CFG_CMD_FPGA	  FPGA device initialization support
616		CFG_CMD_HWFLOW  * RTS/CTS hw flow control
617		CFG_CMD_I2C	* I2C serial bus support
618		CFG_CMD_IDE	* IDE harddisk support
619		CFG_CMD_IMI	  iminfo
620		CFG_CMD_IMLS      List all found images
621		CFG_CMD_IMMAP	* IMMR dump support
622		CFG_CMD_IRQ	* irqinfo
623		CFG_CMD_JFFS2   * JFFS2 Support
624		CFG_CMD_KGDB	* kgdb
625		CFG_CMD_LOADB	  loadb
626		CFG_CMD_LOADS	  loads
627		CFG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
628				  loop, mtest
629		CFG_CMD_MISC      Misc functions like sleep etc
630		CFG_CMD_MMC	  MMC memory mapped support
631		CFG_CMD_MII	  MII utility commands
632		CFG_CMD_NAND    * NAND support
633		CFG_CMD_NET	  bootp, tftpboot, rarpboot
634		CFG_CMD_PCI	* pciinfo
635		CFG_CMD_PCMCIA	* PCMCIA support
636		CFG_CMD_PING    * send ICMP ECHO_REQUEST to network host
637		CFG_CMD_PORTIO    Port I/O
638		CFG_CMD_REGINFO * Register dump
639		CFG_CMD_RUN	  run command in env variable
640		CFG_CMD_SAVES     save S record dump
641		CFG_CMD_SCSI	* SCSI Support
642		CFG_CMD_SDRAM   * print SDRAM configuration information
643		CFG_CMD_SETGETDCR Support for DCR Register access (4xx only)
644		CFG_CMD_SPI	* SPI serial bus support
645		CFG_CMD_USB	* USB support
646		CFG_CMD_VFD     * VFD support (TRAB)
647		CFG_CMD_BSP	* Board SPecific functions
648		-----------------------------------------------
649		CFG_CMD_ALL	all
650
651		CFG_CMD_DFL	Default configuration; at the moment
652				this is includes all commands, except
653				the ones marked with "*" in the list
654				above.
655
656		If you don't define CONFIG_COMMANDS it defaults to
657		CFG_CMD_DFL in include/cmd_confdefs.h. A board can
658		override the default settings in the respective
659		include file.
660
661		EXAMPLE: If you want all functions except of network
662		support you can write:
663
664		#define CONFIG_COMMANDS (CFG_CMD_ALL & ~CFG_CMD_NET)
665
666
667	Note:	Don't enable the "icache" and "dcache" commands
668		(configuration option CFG_CMD_CACHE) unless you know
669		what you (and your U-Boot users) are doing. Data
670		cache cannot be enabled on systems like the 8xx or
671		8260 (where accesses to the IMMR region must be
672		uncached), and it cannot be disabled on all other
673		systems where we (mis-) use the data cache to hold an
674		initial stack and some data.
675
676
677		XXX - this list needs to get updated!
678
679- Watchdog:
680		CONFIG_WATCHDOG
681		If this variable is defined, it enables watchdog
682		support. There must be support in the platform specific
683		code for a watchdog. For the 8xx and 8260 CPUs, the
684		SIU Watchdog feature is enabled in the SYPCR
685		register.
686
687- U-Boot Version:
688		CONFIG_VERSION_VARIABLE
689		If this variable is defined, an environment variable
690		named "ver" is created by U-Boot showing the U-Boot
691		version as printed by the "version" command.
692		This variable is readonly.
693
694- Real-Time Clock:
695
696		When CFG_CMD_DATE is selected, the type of the RTC
697		has to be selected, too. Define exactly one of the
698		following options:
699
700		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
701		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
702		CONFIG_RTC_MC146818	- use MC146818 RTC
703		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
704		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
705		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
706		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
707
708		Note that if the RTC uses I2C, then the I2C interface
709		must also be configured. See I2C Support, below.
710
711- Timestamp Support:
712
713		When CONFIG_TIMESTAMP is selected, the timestamp
714		(date and time) of an image is printed by image
715		commands like bootm or iminfo. This option is
716		automatically enabled when you select CFG_CMD_DATE .
717
718- Partition Support:
719		CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
720		and/or CONFIG_ISO_PARTITION
721
722		If IDE or SCSI support	is  enabled  (CFG_CMD_IDE  or
723		CFG_CMD_SCSI) you must configure support for at least
724		one partition type as well.
725
726- IDE Reset method:
727		CONFIG_IDE_RESET_ROUTINE
728
729		Set this to define that instead of a reset Pin, the
730		routine ide_set_reset(int idereset) will be used.
731
732- ATAPI Support:
733		CONFIG_ATAPI
734
735		Set this to enable ATAPI support.
736
737- SCSI Support:
738		At the moment only there is only support for the
739		SYM53C8XX SCSI controller; define
740		CONFIG_SCSI_SYM53C8XX to enable it.
741
742		CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
743		CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
744		CFG_SCSI_MAX_LUN] can be adjusted to define the
745		maximum numbers of LUNs, SCSI ID's and target
746		devices.
747		CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
748
749- NETWORK Support (PCI):
750		CONFIG_E1000
751		Support for Intel 8254x gigabit chips.
752
753		CONFIG_EEPRO100
754		Support for Intel 82557/82559/82559ER chips.
755		Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom
756		write routine for first time initialisation.
757
758		CONFIG_TULIP
759		Support for Digital 2114x chips.
760		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
761		modem chip initialisation (KS8761/QS6611).
762
763		CONFIG_NATSEMI
764		Support for National dp83815 chips.
765
766		CONFIG_NS8382X
767		Support for National dp8382[01] gigabit chips.
768
769- NETWORK Support (other):
770
771		CONFIG_DRIVER_LAN91C96
772		Support for SMSC's LAN91C96 chips.
773
774			CONFIG_LAN91C96_BASE
775			Define this to hold the physical address
776			of the LAN91C96's I/O space
777
778			CONFIG_LAN91C96_USE_32_BIT
779			Define this to enable 32 bit addressing
780
781- USB Support:
782		At the moment only the UHCI host controller is
783		supported (PIP405, MIP405); define
784		CONFIG_USB_UHCI to enable it.
785		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
786		end define CONFIG_USB_STORAGE to enable the USB
787		storage devices.
788		Note:
789		Supported are USB Keyboards and USB Floppy drives
790		(TEAC FD-05PUB).
791
792- MMC Support:
793		The MMC controller on the Intel PXA is supported. To
794		enable this define CONFIG_MMC. The MMC can be
795		accessed from the boot prompt by mapping the device
796		to physical memory similar to flash. Command line is
797		enabled with CFG_CMD_MMC. The MMC driver also works with
798		the FAT fs. This is enabled with CFG_CMD_FAT.
799
800- Keyboard Support:
801		CONFIG_ISA_KEYBOARD
802
803		Define this to enable standard (PC-Style) keyboard
804		support
805
806		CONFIG_I8042_KBD
807		Standard PC keyboard driver with US (is default) and
808		GERMAN key layout (switch via environment 'keymap=de') support.
809		Export function i8042_kbd_init, i8042_tstc and i8042_getc
810		for cfb_console. Supports cursor blinking.
811
812- Video support:
813		CONFIG_VIDEO
814
815		Define this to enable video support (for output to
816		video).
817
818		CONFIG_VIDEO_CT69000
819
820		Enable Chips & Technologies 69000 Video chip
821
822		CONFIG_VIDEO_SMI_LYNXEM
823		Enable Silicon Motion SMI 712/710/810 Video chip
824		Videomode are selected via environment 'videomode' with
825		standard LiLo mode numbers.
826		Following modes are supported  (* is default):
827
828			    800x600  1024x768  1280x1024
829	      256  (8bit)     303*      305       307
830	    65536 (16bit)     314       317       31a
831	16,7 Mill (24bit)     315       318       31b
832		(i.e. setenv videomode 317; saveenv; reset;)
833
834		CONFIG_VIDEO_SED13806
835		Enable Epson SED13806 driver. This driver supports 8bpp
836		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
837		or CONFIG_VIDEO_SED13806_16BPP
838
839- Keyboard Support:
840		CONFIG_KEYBOARD
841
842		Define this to enable a custom keyboard support.
843		This simply calls drv_keyboard_init() which must be
844		defined in your board-specific files.
845		The only board using this so far is RBC823.
846
847- LCD Support:	CONFIG_LCD
848
849		Define this to enable LCD support (for output to LCD
850		display); also select one of the supported displays
851		by defining one of these:
852
853		CONFIG_NEC_NL6648AC33:
854
855			NEC NL6648AC33-18. Active, color, single scan.
856
857		CONFIG_NEC_NL6648BC20
858
859			NEC NL6648BC20-08. 6.5", 640x480.
860			Active, color, single scan.
861
862		CONFIG_SHARP_16x9
863
864			Sharp 320x240. Active, color, single scan.
865			It isn't 16x9, and I am not sure what it is.
866
867		CONFIG_SHARP_LQ64D341
868
869			Sharp LQ64D341 display, 640x480.
870			Active, color, single scan.
871
872		CONFIG_HLD1045
873
874			HLD1045 display, 640x480.
875			Active, color, single scan.
876
877		CONFIG_OPTREX_BW
878
879			Optrex	 CBL50840-2 NF-FW 99 22 M5
880			or
881			Hitachi	 LMG6912RPFC-00T
882			or
883			Hitachi	 SP14Q002
884
885			320x240. Black & white.
886
887		Normally display is black on white background; define
888		CFG_WHITE_ON_BLACK to get it inverted.
889
890- Splash Screen Support: CONFIG_SPLASH_SCREEN
891
892		If this option is set, the environment is checked for
893		a variable "splashimage". If found, the usual display
894		of logo, copyright and system information on the LCD
895		is supressed and the BMP image at the address
896		specified in "splashimage" is loaded instead. The
897		console is redirected to the "nulldev", too. This
898		allows for a "silent" boot where a splash screen is
899		loaded very quickly after power-on.
900
901- Compression support:
902		CONFIG_BZIP2
903
904		If this option is set, support for bzip2 compressed
905		images is included. If not, only uncompressed and gzip
906		compressed images are supported.
907
908		NOTE: the bzip2 algorithm requires a lot of RAM, so
909		the malloc area (as defined by CFG_MALLOC_LEN) should
910		be at least 4MB.
911
912- Ethernet address:
913		CONFIG_ETHADDR
914		CONFIG_ETH2ADDR
915		CONFIG_ETH3ADDR
916
917		Define a default value for ethernet address to use
918		for the respective ethernet interface, in case this
919		is not determined automatically.
920
921- IP address:
922		CONFIG_IPADDR
923
924		Define a default value for the IP address to use for
925		the default ethernet interface, in case this is not
926		determined through e.g. bootp.
927
928- Server IP address:
929		CONFIG_SERVERIP
930
931		Defines a default value for theIP address of a TFTP
932		server to contact when using the "tftboot" command.
933
934- BOOTP Recovery Mode:
935		CONFIG_BOOTP_RANDOM_DELAY
936
937		If you have many targets in a network that try to
938		boot using BOOTP, you may want to avoid that all
939		systems send out BOOTP requests at precisely the same
940		moment (which would happen for instance at recovery
941		from a power failure, when all systems will try to
942		boot, thus flooding the BOOTP server. Defining
943		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
944		inserted before sending out BOOTP requests. The
945		following delays are insterted then:
946
947		1st BOOTP request:	delay 0 ... 1 sec
948		2nd BOOTP request:	delay 0 ... 2 sec
949		3rd BOOTP request:	delay 0 ... 4 sec
950		4th and following
951		BOOTP requests:		delay 0 ... 8 sec
952
953- DHCP Advanced Options:
954		CONFIG_BOOTP_MASK
955
956		You can fine tune the DHCP functionality by adding
957		these flags to the CONFIG_BOOTP_MASK define:
958
959		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
960		serverip from a DHCP server, it is possible that more
961		than one DNS serverip is offered to the client.
962		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
963		serverip will be stored in the additional environment
964		variable "dnsip2". The first DNS serverip is always
965		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
966		is added to the CONFIG_BOOTP_MASK.
967
968		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
969		to do a dynamic update of a DNS server. To do this, they
970		need the hostname of the DHCP requester.
971		If CONFIG_BOOP_SEND_HOSTNAME is added to the
972		CONFIG_BOOTP_MASK, the content of the "hostname"
973		environment variable is passed as option 12 to
974		the DHCP server.
975
976- Status LED:	CONFIG_STATUS_LED
977
978		Several configurations allow to display the current
979		status using a LED. For instance, the LED will blink
980		fast while running U-Boot code, stop blinking as
981		soon as a reply to a BOOTP request was received, and
982		start blinking slow once the Linux kernel is running
983		(supported by a status LED driver in the Linux
984		kernel). Defining CONFIG_STATUS_LED enables this
985		feature in U-Boot.
986
987- CAN Support:	CONFIG_CAN_DRIVER
988
989		Defining CONFIG_CAN_DRIVER enables CAN driver support
990		on those systems that support this (optional)
991		feature, like the TQM8xxL modules.
992
993- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
994
995		These enable I2C serial bus commands. Defining either of
996		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
997		include the appropriate I2C driver for the selected cpu.
998
999		This will allow you to use i2c commands at the u-boot
1000		command line (as long as you set CFG_CMD_I2C in
1001		CONFIG_COMMANDS) and communicate with i2c based realtime
1002		clock chips. See common/cmd_i2c.c for a description of the
1003		command line interface.
1004
1005		CONFIG_HARD_I2C	selects the CPM hardware driver for I2C.
1006
1007		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1008		bit-banging) driver instead of CPM or similar hardware
1009		support for I2C.
1010
1011		There are several other quantities that must also be
1012		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1013
1014		In both cases you will need to define CFG_I2C_SPEED
1015		to be the frequency (in Hz) at which you wish your i2c bus
1016		to run and CFG_I2C_SLAVE to be the address of this node (ie
1017		the cpu's i2c node address).
1018
1019		Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
1020		sets the cpu up as a master node and so its address should
1021		therefore be cleared to 0 (See, eg, MPC823e User's Manual
1022		p.16-473). So, set CFG_I2C_SLAVE to 0.
1023
1024		That's all that's required for CONFIG_HARD_I2C.
1025
1026		If you use the software i2c interface (CONFIG_SOFT_I2C)
1027		then the following macros need to be defined (examples are
1028		from include/configs/lwmon.h):
1029
1030		I2C_INIT
1031
1032		(Optional). Any commands necessary to enable the I2C
1033		controller or configure ports.
1034
1035		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=  PB_SCL)
1036
1037		I2C_PORT
1038
1039		(Only for MPC8260 CPU). The I/O port to use (the code
1040		assumes both bits are on the same port). Valid values
1041		are 0..3 for ports A..D.
1042
1043		I2C_ACTIVE
1044
1045		The code necessary to make the I2C data line active
1046		(driven).  If the data line is open collector, this
1047		define can be null.
1048
1049		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1050
1051		I2C_TRISTATE
1052
1053		The code necessary to make the I2C data line tri-stated
1054		(inactive).  If the data line is open collector, this
1055		define can be null.
1056
1057		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1058
1059		I2C_READ
1060
1061		Code that returns TRUE if the I2C data line is high,
1062		FALSE if it is low.
1063
1064		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1065
1066		I2C_SDA(bit)
1067
1068		If <bit> is TRUE, sets the I2C data line high. If it
1069		is FALSE, it clears it (low).
1070
1071		eg: #define I2C_SDA(bit) \
1072			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1073			else    immr->im_cpm.cp_pbdat &= ~PB_SDA
1074
1075		I2C_SCL(bit)
1076
1077		If <bit> is TRUE, sets the I2C clock line high. If it
1078		is FALSE, it clears it (low).
1079
1080		eg: #define I2C_SCL(bit) \
1081			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1082			else    immr->im_cpm.cp_pbdat &= ~PB_SCL
1083
1084		I2C_DELAY
1085
1086		This delay is invoked four times per clock cycle so this
1087		controls the rate of data transfer.  The data rate thus
1088		is 1 / (I2C_DELAY * 4). Often defined to be something
1089		like:
1090
1091		#define I2C_DELAY  udelay(2)
1092
1093		CFG_I2C_INIT_BOARD
1094
1095		When a board is reset during an i2c bus transfer
1096		chips might think that the current transfer is still
1097		in progress. On some boards it is possible to access
1098		the i2c SCLK line directly, either by using the
1099		processor pin as a GPIO or by having a second pin
1100		connected to the bus. If this option is defined a
1101		custom i2c_init_board() routine in boards/xxx/board.c
1102		is run early in the boot sequence.
1103
1104- SPI Support:	CONFIG_SPI
1105
1106		Enables SPI driver (so far only tested with
1107		SPI EEPROM, also an instance works with Crystal A/D and
1108		D/As on the SACSng board)
1109
1110		CONFIG_SPI_X
1111
1112		Enables extended (16-bit) SPI EEPROM addressing.
1113		(symmetrical to CONFIG_I2C_X)
1114
1115		CONFIG_SOFT_SPI
1116
1117		Enables a software (bit-bang) SPI driver rather than
1118		using hardware support. This is a general purpose
1119		driver that only requires three general I/O port pins
1120		(two outputs, one input) to function. If this is
1121		defined, the board configuration must define several
1122		SPI configuration items (port pins to use, etc). For
1123		an example, see include/configs/sacsng.h.
1124
1125- FPGA Support: CONFIG_FPGA_COUNT
1126
1127		Specify the number of FPGA devices to support.
1128
1129		CONFIG_FPGA
1130
1131		Used to specify the types of FPGA devices. For
1132		example,
1133		#define CONFIG_FPGA  CFG_XILINX_VIRTEX2
1134
1135		CFG_FPGA_PROG_FEEDBACK
1136
1137		Enable printing of hash marks during FPGA
1138		configuration.
1139
1140		CFG_FPGA_CHECK_BUSY
1141
1142		Enable checks on FPGA configuration interface busy
1143		status by the configuration function. This option
1144		will require a board or device specific function to
1145		be written.
1146
1147		CONFIG_FPGA_DELAY
1148
1149		If defined, a function that provides delays in the
1150		FPGA configuration driver.
1151
1152		CFG_FPGA_CHECK_CTRLC
1153
1154		Allow Control-C to interrupt FPGA configuration
1155
1156		CFG_FPGA_CHECK_ERROR
1157
1158		Check for configuration errors during FPGA bitfile
1159		loading. For example, abort during Virtex II
1160		configuration if the INIT_B line goes low (which
1161		indicated a CRC error).
1162
1163		CFG_FPGA_WAIT_INIT
1164
1165		Maximum time to wait for the INIT_B line to deassert
1166		after PROB_B has been deasserted during a Virtex II
1167		FPGA configuration sequence. The default time is 500 mS.
1168
1169		CFG_FPGA_WAIT_BUSY
1170
1171		Maximum time to wait for BUSY to deassert during
1172		Virtex II FPGA configuration. The default is 5 mS.
1173
1174		CFG_FPGA_WAIT_CONFIG
1175
1176		Time to wait after FPGA configuration. The default is
1177		200 mS.
1178
1179- FPGA Support:	CONFIG_FPGA_COUNT
1180
1181		Specify the number of FPGA devices to support.
1182
1183		CONFIG_FPGA
1184
1185		Used to specify the types of FPGA devices.  For example,
1186		#define CONFIG_FPGA  CFG_XILINX_VIRTEX2
1187
1188		CFG_FPGA_PROG_FEEDBACK
1189
1190		Enable printing of hash marks during FPGA configuration.
1191
1192		CFG_FPGA_CHECK_BUSY
1193
1194		Enable checks on FPGA configuration interface busy
1195		status by the configuration function. This option
1196		will require a board or device specific function to
1197		be written.
1198
1199		CONFIG_FPGA_DELAY
1200
1201		If defined, a function that provides delays in the FPGA
1202		configuration driver.
1203
1204		CFG_FPGA_CHECK_CTRLC
1205		Allow Control-C to interrupt FPGA configuration
1206
1207		CFG_FPGA_CHECK_ERROR
1208
1209		Check for configuration errors during FPGA bitfile
1210		loading. For example, abort during Virtex II
1211		configuration if the INIT_B line goes low (which
1212		indicated a CRC error).
1213
1214		CFG_FPGA_WAIT_INIT
1215
1216		Maximum time to wait for the INIT_B line to deassert
1217		after PROB_B has been deasserted during a Virtex II
1218		FPGA configuration sequence. The default time is 500
1219		mS.
1220
1221		CFG_FPGA_WAIT_BUSY
1222
1223		Maximum time to wait for BUSY to deassert during
1224		Virtex II FPGA configuration. The default is 5 mS.
1225
1226		CFG_FPGA_WAIT_CONFIG
1227
1228		Time to wait after FPGA configuration. The default is
1229		200 mS.
1230
1231- Configuration Management:
1232		CONFIG_IDENT_STRING
1233
1234		If defined, this string will be added to the U-Boot
1235		version information (U_BOOT_VERSION)
1236
1237- Vendor Parameter Protection:
1238
1239		U-Boot considers the values of the environment
1240		variables "serial#" (Board Serial Number) and
1241		"ethaddr" (Ethernet Address) to be parameters that
1242		are set once by the board vendor / manufacturer, and
1243		protects these variables from casual modification by
1244		the user. Once set, these variables are read-only,
1245		and write or delete attempts are rejected. You can
1246		change this behviour:
1247
1248		If CONFIG_ENV_OVERWRITE is #defined in your config
1249		file, the write protection for vendor parameters is
1250		completely disabled. Anybody can change or delete
1251		these parameters.
1252
1253		Alternatively, if you #define _both_ CONFIG_ETHADDR
1254		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1255		ethernet address is installed in the environment,
1256		which can be changed exactly ONCE by the user. [The
1257		serial# is unaffected by this, i. e. it remains
1258		read-only.]
1259
1260- Protected RAM:
1261		CONFIG_PRAM
1262
1263		Define this variable to enable the reservation of
1264		"protected RAM", i. e. RAM which is not overwritten
1265		by U-Boot. Define CONFIG_PRAM to hold the number of
1266		kB you want to reserve for pRAM. You can overwrite
1267		this default value by defining an environment
1268		variable "pram" to the number of kB you want to
1269		reserve. Note that the board info structure will
1270		still show the full amount of RAM. If pRAM is
1271		reserved, a new environment variable "mem" will
1272		automatically be defined to hold the amount of
1273		remaining RAM in a form that can be passed as boot
1274		argument to Linux, for instance like that:
1275
1276			setenv bootargs ... mem=\$(mem)
1277			saveenv
1278
1279		This way you can tell Linux not to use this memory,
1280		either, which results in a memory region that will
1281		not be affected by reboots.
1282
1283		*WARNING* If your board configuration uses automatic
1284		detection of the RAM size, you must make sure that
1285		this memory test is non-destructive. So far, the
1286		following board configurations are known to be
1287		"pRAM-clean":
1288
1289			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1290			HERMES, IP860, RPXlite, LWMON, LANTEC,
1291			PCU_E, FLAGADM, TQM8260
1292
1293- Error Recovery:
1294		CONFIG_PANIC_HANG
1295
1296		Define this variable to stop the system in case of a
1297		fatal error, so that you have to reset it manually.
1298		This is probably NOT a good idea for an embedded
1299		system where you want to system to reboot
1300		automatically as fast as possible, but it may be
1301		useful during development since you can try to debug
1302		the conditions that lead to the situation.
1303
1304		CONFIG_NET_RETRY_COUNT
1305
1306		This variable defines the number of retries for
1307		network operations like ARP, RARP, TFTP, or BOOTP
1308		before giving up the operation. If not defined, a
1309		default value of 5 is used.
1310
1311- Command Interpreter:
1312		CFG_HUSH_PARSER
1313
1314		Define this variable to enable the "hush" shell (from
1315		Busybox) as command line interpreter, thus enabling
1316		powerful command line syntax like
1317		if...then...else...fi conditionals or `&&' and '||'
1318		constructs ("shell scripts").
1319
1320		If undefined, you get the old, much simpler behaviour
1321		with a somewhat smaller memory footprint.
1322
1323
1324		CFG_PROMPT_HUSH_PS2
1325
1326		This defines the secondary prompt string, which is
1327		printed when the command interpreter needs more input
1328		to complete a command. Usually "> ".
1329
1330	Note:
1331
1332		In the current implementation, the local variables
1333		space and global environment variables space are
1334		separated. Local variables are those you define by
1335		simply typing `name=value'. To access a local
1336		variable later on, you have write `$name' or
1337		`${name}'; to execute the contents of a variable
1338		directly type `$name' at the command prompt.
1339
1340		Global environment variables are those you use
1341		setenv/printenv to work with. To run a command stored
1342		in such a variable, you need to use the run command,
1343		and you must not use the '$' sign to access them.
1344
1345		To store commands and special characters in a
1346		variable, please use double quotation marks
1347		surrounding the whole text of the variable, instead
1348		of the backslashes before semicolons and special
1349		symbols.
1350
1351- Default Environment
1352		CONFIG_EXTRA_ENV_SETTINGS
1353
1354		Define this to contain any number of null terminated
1355		strings (variable = value pairs) that will be part of
1356		the default environment compiled into the boot image.
1357
1358		For example, place something like this in your
1359		board's config file:
1360
1361		#define CONFIG_EXTRA_ENV_SETTINGS \
1362			"myvar1=value1\0" \
1363			"myvar2=value2\0"
1364
1365		Warning: This method is based on knowledge about the
1366		internal format how the environment is stored by the
1367		U-Boot code. This is NOT an official, exported
1368		interface! Although it is unlikely that this format
1369		will change soon, there is no guarantee either.
1370		You better know what you are doing here.
1371
1372		Note: overly (ab)use of the default environment is
1373		discouraged. Make sure to check other ways to preset
1374		the environment like the autoscript function or the
1375		boot command first.
1376
1377- DataFlash Support
1378		CONFIG_HAS_DATAFLASH
1379
1380		Defining this option enables DataFlash features and
1381		allows to read/write in Dataflash via the standard
1382		commands cp, md...
1383
1384- Show boot progress
1385		CONFIG_SHOW_BOOT_PROGRESS
1386
1387		Defining this option allows to add some board-
1388		specific code (calling a user-provided function
1389		"show_boot_progress(int)") that enables you to show
1390		the system's boot progress on some display (for
1391		example, some LED's) on your board. At the moment,
1392		the following checkpoints are implemented:
1393
1394  Arg	Where			When
1395    1	common/cmd_bootm.c	before attempting to boot an image
1396   -1	common/cmd_bootm.c	Image header has bad     magic number
1397    2	common/cmd_bootm.c	Image header has correct magic number
1398   -2	common/cmd_bootm.c	Image header has bad     checksum
1399    3	common/cmd_bootm.c	Image header has correct checksum
1400   -3	common/cmd_bootm.c	Image data   has bad     checksum
1401    4	common/cmd_bootm.c	Image data   has correct checksum
1402   -4	common/cmd_bootm.c	Image is for unsupported architecture
1403    5	common/cmd_bootm.c	Architecture check OK
1404   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi, standalone)
1405    6	common/cmd_bootm.c	Image Type check OK
1406   -6	common/cmd_bootm.c	gunzip uncompression error
1407   -7	common/cmd_bootm.c	Unimplemented compression type
1408    7	common/cmd_bootm.c	Uncompression OK
1409   -8	common/cmd_bootm.c	Wrong Image Type (not kernel, multi, standalone)
1410    8	common/cmd_bootm.c	Image Type check OK
1411   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
1412    9	common/cmd_bootm.c	Start initial ramdisk verification
1413  -10	common/cmd_bootm.c	Ramdisk header has bad     magic number
1414  -11	common/cmd_bootm.c	Ramdisk header has bad     checksum
1415   10	common/cmd_bootm.c	Ramdisk header is OK
1416  -12	common/cmd_bootm.c	Ramdisk data   has bad     checksum
1417   11	common/cmd_bootm.c	Ramdisk data   has correct checksum
1418   12	common/cmd_bootm.c	Ramdisk verification complete, start loading
1419  -13	common/cmd_bootm.c	Wrong Image Type (not PPC Linux Ramdisk)
1420   13	common/cmd_bootm.c	Start multifile image verification
1421   14	common/cmd_bootm.c	No initial ramdisk, no multifile, continue.
1422   15	common/cmd_bootm.c	All preparation done, transferring control to OS
1423
1424   -1	common/cmd_doc.c	Bad usage of "doc" command
1425   -1	common/cmd_doc.c	No boot device
1426   -1	common/cmd_doc.c	Unknown Chip ID on boot device
1427   -1	common/cmd_doc.c	Read Error on boot device
1428   -1	common/cmd_doc.c	Image header has bad magic number
1429
1430   -1	common/cmd_ide.c	Bad usage of "ide" command
1431   -1	common/cmd_ide.c	No boot device
1432   -1	common/cmd_ide.c	Unknown boot device
1433   -1	common/cmd_ide.c	Unknown partition table
1434   -1	common/cmd_ide.c	Invalid partition type
1435   -1	common/cmd_ide.c	Read Error on boot device
1436   -1	common/cmd_ide.c	Image header has bad magic number
1437
1438   -1	common/cmd_nand.c	Bad usage of "nand" command
1439   -1	common/cmd_nand.c	No boot device
1440   -1	common/cmd_nand.c	Unknown Chip ID on boot device
1441   -1	common/cmd_nand.c	Read Error on boot device
1442   -1	common/cmd_nand.c	Image header has bad magic number
1443
1444   -1	common/env_common.c     Environment has a bad CRC, using default
1445
1446
1447Modem Support:
1448--------------
1449
1450[so far only for SMDK2400 and TRAB boards]
1451
1452- Modem support endable:
1453		CONFIG_MODEM_SUPPORT
1454
1455- RTS/CTS Flow control enable:
1456		CONFIG_HWFLOW
1457
1458- Modem debug support:
1459		CONFIG_MODEM_SUPPORT_DEBUG
1460
1461		Enables debugging stuff (char screen[1024], dbg())
1462		for modem support. Useful only with BDI2000.
1463
1464- General:
1465
1466		In the target system modem support is enabled when a
1467		specific key (key combination) is pressed during
1468		power-on. Otherwise U-Boot will boot normally
1469		(autoboot). The key_pressed() fuction is called from
1470		board_init(). Currently key_pressed() is a dummy
1471		function, returning 1 and thus enabling modem
1472		initialization.
1473
1474		If there are no modem init strings in the
1475		environment, U-Boot proceed to autoboot; the
1476		previous output (banner, info printfs) will be
1477		supressed, though.
1478
1479		See also: doc/README.Modem
1480
1481
1482Configuration Settings:
1483-----------------------
1484
1485- CFG_LONGHELP: Defined when you want long help messages included;
1486		undefine this when you're short of memory.
1487
1488- CFG_PROMPT:	This is what U-Boot prints on the console to
1489		prompt for user input.
1490
1491- CFG_CBSIZE:	Buffer size for input from the Console
1492
1493- CFG_PBSIZE:	Buffer size for Console output
1494
1495- CFG_MAXARGS:	max. Number of arguments accepted for monitor commands
1496
1497- CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1498		the application (usually a Linux kernel) when it is
1499		booted
1500
1501- CFG_BAUDRATE_TABLE:
1502		List of legal baudrate settings for this board.
1503
1504- CFG_CONSOLE_INFO_QUIET
1505		Suppress display of console information at boot.
1506
1507- CFG_CONSOLE_IS_IN_ENV
1508		If the board specific function
1509			extern int overwrite_console (void);
1510		returns 1, the stdin, stderr and stdout are switched to the
1511		serial port, else the settings in the environment are used.
1512
1513- CFG_CONSOLE_OVERWRITE_ROUTINE
1514		Enable the call to overwrite_console().
1515
1516- CFG_CONSOLE_ENV_OVERWRITE
1517		Enable overwrite of previous console environment settings.
1518
1519- CFG_MEMTEST_START, CFG_MEMTEST_END:
1520		Begin and End addresses of the area used by the
1521		simple memory test.
1522
1523- CFG_ALT_MEMTEST:
1524		Enable an alternate, more extensive memory test.
1525
1526- CFG_MEMTEST_SCRATCH:
1527		Scratch address used by the alternate memory test
1528		You only need to set this if address zero isn't writeable
1529
1530- CFG_TFTP_LOADADDR:
1531		Default load address for network file downloads
1532
1533- CFG_LOADS_BAUD_CHANGE:
1534		Enable temporary baudrate change while serial download
1535
1536- CFG_SDRAM_BASE:
1537		Physical start address of SDRAM. _Must_ be 0 here.
1538
1539- CFG_MBIO_BASE:
1540		Physical start address of Motherboard I/O (if using a
1541		Cogent motherboard)
1542
1543- CFG_FLASH_BASE:
1544		Physical start address of Flash memory.
1545
1546- CFG_MONITOR_BASE:
1547		Physical start address of boot monitor code (set by
1548		make config files to be same as the text base address
1549		(TEXT_BASE) used when linking) - same as
1550		CFG_FLASH_BASE when booting from flash.
1551
1552- CFG_MONITOR_LEN:
1553		Size of memory reserved for monitor code, used to
1554		determine _at_compile_time_ (!) if the environment is
1555		embedded within the U-Boot image, or in a separate
1556		flash sector.
1557
1558- CFG_MALLOC_LEN:
1559		Size of DRAM reserved for malloc() use.
1560
1561- CFG_BOOTMAPSZ:
1562		Maximum size of memory mapped by the startup code of
1563		the Linux kernel; all data that must be processed by
1564		the Linux kernel (bd_info, boot arguments, eventually
1565		initrd image) must be put below this limit.
1566
1567- CFG_MAX_FLASH_BANKS:
1568		Max number of Flash memory banks
1569
1570- CFG_MAX_FLASH_SECT:
1571		Max number of sectors on a Flash chip
1572
1573- CFG_FLASH_ERASE_TOUT:
1574		Timeout for Flash erase operations (in ms)
1575
1576- CFG_FLASH_WRITE_TOUT:
1577		Timeout for Flash write operations (in ms)
1578
1579- CFG_FLASH_LOCK_TOUT
1580		Timeout for Flash set sector lock bit operation (in ms)
1581
1582- CFG_FLASH_UNLOCK_TOUT
1583		Timeout for Flash clear lock bits operation (in ms)
1584
1585- CFG_FLASH_PROTECTION
1586		If defined, hardware flash sectors protection is used
1587		instead of U-Boot software protection.
1588
1589- CFG_DIRECT_FLASH_TFTP:
1590
1591		Enable TFTP transfers directly to flash memory;
1592		without this option such a download has to be
1593		performed in two steps: (1) download to RAM, and (2)
1594		copy from RAM to flash.
1595
1596		The two-step approach is usually more reliable, since
1597		you can check if the download worked before you erase
1598		the flash, but in some situations (when sytem RAM is
1599		too limited to allow for a tempory copy of the
1600		downloaded image) this option may be very useful.
1601
1602- CFG_FLASH_CFI:
1603		Define if the flash driver uses extra elements in the
1604		common flash structure for storing flash geometry
1605
1606- CFG_RX_ETH_BUFFER:
1607		Defines the number of ethernet receive buffers. On some
1608		ethernet controllers it is recommended to set this value
1609		to 8 or even higher (EEPRO100 or 405 EMAC), since all
1610		buffers can be full shortly after enabling the interface
1611		on high ethernet traffic.
1612		Defaults to 4 if not defined.
1613
1614The following definitions that deal with the placement and management
1615of environment data (variable area); in general, we support the
1616following configurations:
1617
1618- CFG_ENV_IS_IN_FLASH:
1619
1620	Define this if the environment is in flash memory.
1621
1622	a) The environment occupies one whole flash sector, which is
1623	   "embedded" in the text segment with the U-Boot code. This
1624	   happens usually with "bottom boot sector" or "top boot
1625	   sector" type flash chips, which have several smaller
1626	   sectors at the start or the end. For instance, such a
1627	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
1628	   such a case you would place the environment in one of the
1629	   4 kB sectors - with U-Boot code before and after it. With
1630	   "top boot sector" type flash chips, you would put the
1631	   environment in one of the last sectors, leaving a gap
1632	   between U-Boot and the environment.
1633
1634	- CFG_ENV_OFFSET:
1635
1636	   Offset of environment data (variable area) to the
1637	   beginning of flash memory; for instance, with bottom boot
1638	   type flash chips the second sector can be used: the offset
1639	   for this sector is given here.
1640
1641	   CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
1642
1643	- CFG_ENV_ADDR:
1644
1645	   This is just another way to specify the start address of
1646	   the flash sector containing the environment (instead of
1647	   CFG_ENV_OFFSET).
1648
1649	- CFG_ENV_SECT_SIZE:
1650
1651	   Size of the sector containing the environment.
1652
1653
1654	b) Sometimes flash chips have few, equal sized, BIG sectors.
1655	   In such a case you don't want to spend a whole sector for
1656	   the environment.
1657
1658	- CFG_ENV_SIZE:
1659
1660	   If you use this in combination with CFG_ENV_IS_IN_FLASH
1661	   and CFG_ENV_SECT_SIZE, you can specify to use only a part
1662	   of this flash sector for the environment. This saves
1663	   memory for the RAM copy of the environment.
1664
1665	   It may also save flash memory if you decide to use this
1666	   when your environment is "embedded" within U-Boot code,
1667	   since then the remainder of the flash sector could be used
1668	   for U-Boot code. It should be pointed out that this is
1669	   STRONGLY DISCOURAGED from a robustness point of view:
1670	   updating the environment in flash makes it always
1671	   necessary to erase the WHOLE sector. If something goes
1672	   wrong before the contents has been restored from a copy in
1673	   RAM, your target system will be dead.
1674
1675	- CFG_ENV_ADDR_REDUND
1676	  CFG_ENV_SIZE_REDUND
1677
1678	   These settings describe a second storage area used to hold
1679	   a redundand copy of the environment data, so that there is
1680	   a valid backup copy in case there is a power failure during
1681	   a "saveenv" operation.
1682
1683BE CAREFUL! Any changes to the flash layout, and some changes to the
1684source code will make it necessary to adapt <board>/u-boot.lds*
1685accordingly!
1686
1687
1688- CFG_ENV_IS_IN_NVRAM:
1689
1690	Define this if you have some non-volatile memory device
1691	(NVRAM, battery buffered SRAM) which you want to use for the
1692	environment.
1693
1694	- CFG_ENV_ADDR:
1695	- CFG_ENV_SIZE:
1696
1697	  These two #defines are used to determin the memory area you
1698	  want to use for environment. It is assumed that this memory
1699	  can just be read and written to, without any special
1700	  provision.
1701
1702BE CAREFUL! The first access to the environment happens quite early
1703in U-Boot initalization (when we try to get the setting of for the
1704console baudrate). You *MUST* have mappend your NVRAM area then, or
1705U-Boot will hang.
1706
1707Please note that even with NVRAM we still use a copy of the
1708environment in RAM: we could work on NVRAM directly, but we want to
1709keep settings there always unmodified except somebody uses "saveenv"
1710to save the current settings.
1711
1712
1713- CFG_ENV_IS_IN_EEPROM:
1714
1715	Use this if you have an EEPROM or similar serial access
1716	device and a driver for it.
1717
1718	- CFG_ENV_OFFSET:
1719	- CFG_ENV_SIZE:
1720
1721	  These two #defines specify the offset and size of the
1722	  environment area within the total memory of your EEPROM.
1723
1724	- CFG_I2C_EEPROM_ADDR:
1725	  If defined, specified the chip address of the EEPROM device.
1726	  The default address is zero.
1727
1728	- CFG_EEPROM_PAGE_WRITE_BITS:
1729	  If defined, the number of bits used to address bytes in a
1730	  single page in the EEPROM device.  A 64 byte page, for example
1731	  would require six bits.
1732
1733	- CFG_EEPROM_PAGE_WRITE_DELAY_MS:
1734	  If defined, the number of milliseconds to delay between
1735	  page writes.  The default is zero milliseconds.
1736
1737	- CFG_I2C_EEPROM_ADDR_LEN:
1738	  The length in bytes of the EEPROM memory array address.  Note
1739	  that this is NOT the chip address length!
1740
1741	- CFG_EEPROM_SIZE:
1742	  The size in bytes of the EEPROM device.
1743
1744
1745- CFG_SPI_INIT_OFFSET
1746
1747	Defines offset to the initial SPI buffer area in DPRAM. The
1748	area is used at an early stage (ROM part) if the environment
1749	is configured to reside in the SPI EEPROM: We need a 520 byte
1750	scratch DPRAM area. It is used between the two initialization
1751	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
1752	to be a good choice since it makes it far enough from the
1753	start of the data area as well as from the stack pointer.
1754
1755Please note that the environment is read-only as long as the monitor
1756has been relocated to RAM and a RAM copy of the environment has been
1757created; also, when using EEPROM you will have to use getenv_r()
1758until then to read environment variables.
1759
1760The environment is protected by a CRC32 checksum. Before the monitor
1761is relocated into RAM, as a result of a bad CRC you will be working
1762with the compiled-in default environment - *silently*!!! [This is
1763necessary, because the first environment variable we need is the
1764"baudrate" setting for the console - if we have a bad CRC, we don't
1765have any device yet where we could complain.]
1766
1767Note: once the monitor has been relocated, then it will complain if
1768the default environment is used; a new CRC is computed as soon as you
1769use the "saveenv" command to store a valid environment.
1770
1771- CFG_FAULT_ECHO_LINK_DOWN:
1772		Echo the inverted Ethernet link state to the fault LED.
1773
1774		Note: If this option is active, then CFG_FAULT_MII_ADDR
1775		      also needs to be defined.
1776
1777- CFG_FAULT_MII_ADDR:
1778		MII address of the PHY to check for the Ethernet link state.
1779
1780Low Level (hardware related) configuration options:
1781---------------------------------------------------
1782
1783- CFG_CACHELINE_SIZE:
1784		Cache Line Size of the CPU.
1785
1786- CFG_DEFAULT_IMMR:
1787		Default address of the IMMR after system reset.
1788
1789		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
1790		and RPXsuper) to be able to adjust the position of
1791		the IMMR register after a reset.
1792
1793- Floppy Disk Support:
1794		CFG_FDC_DRIVE_NUMBER
1795
1796		the default drive number (default value 0)
1797
1798		CFG_ISA_IO_STRIDE
1799
1800		defines the spacing between fdc chipset registers
1801		(default value 1)
1802
1803		CFG_ISA_IO_OFFSET
1804
1805		defines the offset of register from address. It
1806		depends on which part of the data bus is connected to
1807		the fdc chipset. (default value 0)
1808
1809		If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
1810		CFG_FDC_DRIVE_NUMBER are undefined, they take their
1811		default value.
1812
1813		if CFG_FDC_HW_INIT is defined, then the function
1814		fdc_hw_init() is called at the beginning of the FDC
1815		setup. fdc_hw_init() must be provided by the board
1816		source code. It is used to make hardware dependant
1817		initializations.
1818
1819- CFG_IMMR:	Physical address of the Internal Memory Mapped
1820		Register; DO NOT CHANGE! (11-4)
1821		[MPC8xx systems only]
1822
1823- CFG_INIT_RAM_ADDR:
1824
1825		Start address of memory area that can be used for
1826		initial data and stack; please note that this must be
1827		writable memory that is working WITHOUT special
1828		initialization, i. e. you CANNOT use normal RAM which
1829		will become available only after programming the
1830		memory controller and running certain initialization
1831		sequences.
1832
1833		U-Boot uses the following memory types:
1834		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
1835		- MPC824X: data cache
1836		- PPC4xx:  data cache
1837
1838- CFG_GBL_DATA_OFFSET:
1839
1840		Offset of the initial data structure in the memory
1841		area defined by CFG_INIT_RAM_ADDR. Usually
1842		CFG_GBL_DATA_OFFSET is chosen such that the initial
1843		data is located at the end of the available space
1844		(sometimes written as (CFG_INIT_RAM_END -
1845		CFG_INIT_DATA_SIZE), and the initial stack is just
1846		below that area (growing from (CFG_INIT_RAM_ADDR +
1847		CFG_GBL_DATA_OFFSET) downward.
1848
1849	Note:
1850		On the MPC824X (or other systems that use the data
1851		cache for initial memory) the address chosen for
1852		CFG_INIT_RAM_ADDR is basically arbitrary - it must
1853		point to an otherwise UNUSED address space between
1854		the top of RAM and the start of the PCI space.
1855
1856- CFG_SIUMCR:	SIU Module Configuration (11-6)
1857
1858- CFG_SYPCR:	System Protection Control (11-9)
1859
1860- CFG_TBSCR:	Time Base Status and Control (11-26)
1861
1862- CFG_PISCR:	Periodic Interrupt Status and Control (11-31)
1863
1864- CFG_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
1865
1866- CFG_SCCR:	System Clock and reset Control Register (15-27)
1867
1868- CFG_OR_TIMING_SDRAM:
1869		SDRAM timing
1870
1871- CFG_MAMR_PTA:
1872		periodic timer for refresh
1873
1874- CFG_DER:	Debug Event Register (37-47)
1875
1876- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
1877  CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
1878  CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
1879  CFG_BR1_PRELIM:
1880		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
1881
1882- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
1883  CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
1884  CFG_OR3_PRELIM, CFG_BR3_PRELIM:
1885		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
1886
1887- CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
1888  CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
1889		Machine Mode Register and Memory Periodic Timer
1890		Prescaler definitions (SDRAM timing)
1891
1892- CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
1893		enable I2C microcode relocation patch (MPC8xx);
1894		define relocation offset in DPRAM [DSP2]
1895
1896- CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
1897		enable SPI microcode relocation patch (MPC8xx);
1898		define relocation offset in DPRAM [SCC4]
1899
1900- CFG_USE_OSCCLK:
1901		Use OSCM clock mode on MBX8xx board. Be careful,
1902		wrong setting might damage your board. Read
1903		doc/README.MBX before setting this variable!
1904
1905- CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
1906		Offset of the bootmode word in DPRAM used by post
1907		(Power On Self Tests). This definition overrides
1908		#define'd default value in commproc.h resp.
1909		cpm_8260.h.
1910
1911- CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
1912  CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
1913  CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
1914  CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
1915  CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
1916  CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
1917  CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
1918  CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
1919		Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
1920
1921Building the Software:
1922======================
1923
1924Building U-Boot has been tested in native PPC environments (on a
1925PowerBook G3 running LinuxPPC 2000) and in cross environments
1926(running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
1927NetBSD 1.5 on x86).
1928
1929If you are not using a native PPC environment, it is assumed that you
1930have the GNU cross compiling tools available in your path and named
1931with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
1932you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
1933the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
1934change it to:
1935
1936	CROSS_COMPILE = ppc_4xx-
1937
1938
1939U-Boot is intended to be  simple  to  build.  After  installing  the
1940sources	 you must configure U-Boot for one specific board type. This
1941is done by typing:
1942
1943	make NAME_config
1944
1945where "NAME_config" is the name of one of the existing
1946configurations; the following names are supported:
1947
1948    ADCIOP_config	  GTH_config		TQM850L_config
1949    ADS860_config	  IP860_config		TQM855L_config
1950    AR405_config	  IVML24_config		TQM860L_config
1951    CANBT_config	  IVMS8_config		WALNUT405_config
1952    CPCI405_config	  LANTEC_config		cogent_common_config
1953    CPCIISER4_config	  MBX_config		cogent_mpc8260_config
1954    CU824_config	  MBX860T_config	cogent_mpc8xx_config
1955    ESTEEM192E_config	  RPXlite_config	hermes_config
1956    ETX094_config	  RPXsuper_config	hymod_config
1957    FADS823_config	  SM850_config		lwmon_config
1958    FADS850SAR_config	  SPD823TS_config	pcu_e_config
1959    FADS860T_config	  SXNI855T_config	rsdproto_config
1960    FPS850L_config	  Sandpoint8240_config	sbc8260_config
1961    GENIETV_config	  TQM823L_config	PIP405_config
1962    GEN860T_config	  EBONY_config		FPS860L_config
1963    ELPT860_config	  cmi_mpc5xx_config	NETVIA_config
1964    at91rm9200dk_config	  omap1510inn_config	MPC8260ADS_config
1965    omap1610inn_config	  ZPC1900_config	MPC8540ADS_config
1966    MPC8560ADS_config
1967
1968Note: for some board special configuration names may exist; check  if
1969      additional  information is available from the board vendor; for
1970      instance, the TQM8xxL systems run normally at 50 MHz and use  a
1971      SCC  for	10baseT	 ethernet; there are also systems with 80 MHz
1972      CPU clock, and an optional Fast Ethernet	module	is  available
1973      for  CPU's  with FEC. You can select such additional "features"
1974      when chosing the configuration, i. e.
1975
1976      make TQM860L_config
1977	- will configure for a plain TQM860L, i. e. 50MHz, no FEC
1978
1979      make TQM860L_FEC_config
1980	- will configure for a TQM860L at 50MHz with FEC for ethernet
1981
1982      make TQM860L_80MHz_config
1983	- will configure for a TQM860L at 80 MHz, with normal 10baseT
1984	  interface
1985
1986      make TQM860L_FEC_80MHz_config
1987	- will configure for a TQM860L at 80 MHz with FEC for ethernet
1988
1989      make TQM823L_LCD_config
1990	- will configure for a TQM823L with U-Boot console on LCD
1991
1992      make TQM823L_LCD_80MHz_config
1993	- will configure for a TQM823L at 80 MHz with U-Boot console on LCD
1994
1995      etc.
1996
1997
1998Finally, type "make all", and you should get some working U-Boot
1999images ready for download to / installation on your system:
2000
2001- "u-boot.bin" is a raw binary image
2002- "u-boot" is an image in ELF binary format
2003- "u-boot.srec" is in Motorola S-Record format
2004
2005
2006Please be aware that the Makefiles assume you are using GNU make, so
2007for instance on NetBSD you might need to use "gmake" instead of
2008native "make".
2009
2010
2011If the system board that you have is not listed, then you will need
2012to port U-Boot to your hardware platform. To do this, follow these
2013steps:
2014
20151.  Add a new configuration option for your board to the toplevel
2016    "Makefile" and to the "MAKEALL" script, using the existing
2017    entries as examples. Note that here and at many other places
2018    boards and other names are listed in alphabetical sort order. Please
2019    keep this order.
20202.  Create a new directory to hold your board specific code. Add any
2021    files you need. In your board directory, you will need at least
2022    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
20233.  Create a new configuration file "include/configs/<board>.h" for
2024    your board
20253.  If you're porting U-Boot to a new CPU, then also create a new
2026    directory to hold your CPU specific code. Add any files you need.
20274.  Run "make <board>_config" with your new name.
20285.  Type "make", and you should get a working "u-boot.srec" file
2029    to be installed on your target system.
20306.  Debug and solve any problems that might arise.
2031    [Of course, this last step is much harder than it sounds.]
2032
2033
2034Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2035==============================================================
2036
2037If you have modified U-Boot sources (for instance added a new	board
2038or  support  for  new  devices,	 a new CPU, etc.) you are expected to
2039provide feedback to the other developers. The feedback normally takes
2040the form of a "patch", i. e. a context diff against a certain (latest
2041official or latest in CVS) version of U-Boot sources.
2042
2043But before you submit such a patch, please verify that	your  modifi-
2044cation	did not break existing code. At least make sure that *ALL* of
2045the supported boards compile WITHOUT ANY compiler warnings. To do so,
2046just run the "MAKEALL" script, which will configure and build U-Boot
2047for ALL supported system. Be warned, this will take a while. You  can
2048select	which  (cross)	compiler  to use by passing a `CROSS_COMPILE'
2049environment variable to the script, i. e. to use the cross tools from
2050MontaVista's Hard Hat Linux you can type
2051
2052	CROSS_COMPILE=ppc_8xx- MAKEALL
2053
2054or to build on a native PowerPC system you can type
2055
2056	CROSS_COMPILE=' ' MAKEALL
2057
2058See also "U-Boot Porting Guide" below.
2059
2060
2061Monitor Commands - Overview:
2062============================
2063
2064go	- start application at address 'addr'
2065run	- run commands in an environment variable
2066bootm	- boot application image from memory
2067bootp	- boot image via network using BootP/TFTP protocol
2068tftpboot- boot image via network using TFTP protocol
2069	       and env variables "ipaddr" and "serverip"
2070	       (and eventually "gatewayip")
2071rarpboot- boot image via network using RARP/TFTP protocol
2072diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
2073loads	- load S-Record file over serial line
2074loadb	- load binary file over serial line (kermit mode)
2075md	- memory display
2076mm	- memory modify (auto-incrementing)
2077nm	- memory modify (constant address)
2078mw	- memory write (fill)
2079cp	- memory copy
2080cmp	- memory compare
2081crc32	- checksum calculation
2082imd     - i2c memory display
2083imm     - i2c memory modify (auto-incrementing)
2084inm     - i2c memory modify (constant address)
2085imw     - i2c memory write (fill)
2086icrc32  - i2c checksum calculation
2087iprobe  - probe to discover valid I2C chip addresses
2088iloop   - infinite loop on address range
2089isdram  - print SDRAM configuration information
2090sspi    - SPI utility commands
2091base	- print or set address offset
2092printenv- print environment variables
2093setenv	- set environment variables
2094saveenv - save environment variables to persistent storage
2095protect - enable or disable FLASH write protection
2096erase	- erase FLASH memory
2097flinfo	- print FLASH memory information
2098bdinfo	- print Board Info structure
2099iminfo	- print header information for application image
2100coninfo - print console devices and informations
2101ide	- IDE sub-system
2102loop	- infinite loop on address range
2103mtest	- simple RAM test
2104icache	- enable or disable instruction cache
2105dcache	- enable or disable data cache
2106reset	- Perform RESET of the CPU
2107echo	- echo args to console
2108version - print monitor version
2109help	- print online help
2110?	- alias for 'help'
2111
2112
2113Monitor Commands - Detailed Description:
2114========================================
2115
2116TODO.
2117
2118For now: just type "help <command>".
2119
2120
2121Environment Variables:
2122======================
2123
2124U-Boot supports user configuration using Environment Variables which
2125can be made persistent by saving to Flash memory.
2126
2127Environment Variables are set using "setenv", printed using
2128"printenv", and saved to Flash using "saveenv". Using "setenv"
2129without a value can be used to delete a variable from the
2130environment. As long as you don't save the environment you are
2131working with an in-memory copy. In case the Flash area containing the
2132environment is erased by accident, a default environment is provided.
2133
2134Some configuration options can be set using Environment Variables:
2135
2136  baudrate	- see CONFIG_BAUDRATE
2137
2138  bootdelay	- see CONFIG_BOOTDELAY
2139
2140  bootcmd	- see CONFIG_BOOTCOMMAND
2141
2142  bootargs	- Boot arguments when booting an RTOS image
2143
2144  bootfile	- Name of the image to load with TFTP
2145
2146  autoload	- if set to "no" (any string beginning with 'n'),
2147		  "bootp" will just load perform a lookup of the
2148		  configuration from the BOOTP server, but not try to
2149		  load any image using TFTP
2150
2151  autostart	- if set to "yes", an image loaded using the "bootp",
2152		  "rarpboot", "tftpboot" or "diskboot" commands will
2153		  be automatically started (by internally calling
2154		  "bootm")
2155
2156		  If set to "no", a standalone image passed to the
2157		  "bootm" command will be copied to the load address
2158		  (and eventually uncompressed), but NOT be started.
2159		  This can be used to load and uncompress arbitrary
2160		  data.
2161
2162  initrd_high	- restrict positioning of initrd images:
2163		  If this variable is not set, initrd images will be
2164		  copied to the highest possible address in RAM; this
2165		  is usually what you want since it allows for
2166		  maximum initrd size. If for some reason you want to
2167		  make sure that the initrd image is loaded below the
2168		  CFG_BOOTMAPSZ limit, you can set this environment
2169		  variable to a value of "no" or "off" or "0".
2170		  Alternatively, you can set it to a maximum upper
2171		  address to use (U-Boot will still check that it
2172		  does not overwrite the U-Boot stack and data).
2173
2174		  For instance, when you have a system with 16 MB
2175		  RAM, and want to reserve 4 MB from use by Linux,
2176		  you can do this by adding "mem=12M" to the value of
2177		  the "bootargs" variable. However, now you must make
2178		  sure that the initrd image is placed in the first
2179		  12 MB as well - this can be done with
2180
2181		  setenv initrd_high 00c00000
2182
2183		  If you set initrd_high to 0xFFFFFFFF, this is an
2184		  indication to U-Boot that all addresses are legal
2185		  for the Linux kernel, including addresses in flash
2186		  memory. In this case U-Boot will NOT COPY the
2187		  ramdisk at all. This may be useful to reduce the
2188		  boot time on your system, but requires that this
2189		  feature is supported by your Linux kernel.
2190
2191  ipaddr	- IP address; needed for tftpboot command
2192
2193  loadaddr	- Default load address for commands like "bootp",
2194		  "rarpboot", "tftpboot", "loadb" or "diskboot"
2195
2196  loads_echo	- see CONFIG_LOADS_ECHO
2197
2198  serverip	- TFTP server IP address; needed for tftpboot command
2199
2200  bootretry	- see CONFIG_BOOT_RETRY_TIME
2201
2202  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
2203
2204  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
2205
2206
2207The following environment variables may be used and automatically
2208updated by the network boot commands ("bootp" and "rarpboot"),
2209depending the information provided by your boot server:
2210
2211  bootfile	- see above
2212  dnsip		- IP address of your Domain Name Server
2213  dnsip2	- IP address of your secondary Domain Name Server
2214  gatewayip	- IP address of the Gateway (Router) to use
2215  hostname	- Target hostname
2216  ipaddr	- see above
2217  netmask	- Subnet Mask
2218  rootpath	- Pathname of the root filesystem on the NFS server
2219  serverip	- see above
2220
2221
2222There are two special Environment Variables:
2223
2224  serial#	- contains hardware identification information such
2225		  as type string and/or serial number
2226  ethaddr	- Ethernet address
2227
2228These variables can be set only once (usually during manufacturing of
2229the board). U-Boot refuses to delete or overwrite these variables
2230once they have been set once.
2231
2232
2233Further special Environment Variables:
2234
2235  ver		- Contains the U-Boot version string as printed
2236		  with the "version" command. This variable is
2237		  readonly (see CONFIG_VERSION_VARIABLE).
2238
2239
2240Please note that changes to some configuration parameters may take
2241only effect after the next boot (yes, that's just like Windoze :-).
2242
2243
2244Command Line Parsing:
2245=====================
2246
2247There are two different command line parsers available with U-Boot:
2248the old "simple" one, and the much more powerful "hush" shell:
2249
2250Old, simple command line parser:
2251--------------------------------
2252
2253- supports environment variables (through setenv / saveenv commands)
2254- several commands on one line, separated by ';'
2255- variable substitution using "... $(name) ..." syntax
2256- special characters ('$', ';') can be escaped by prefixing with '\',
2257  for example:
2258	setenv bootcmd bootm \$(address)
2259- You can also escape text by enclosing in single apostrophes, for example:
2260	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
2261
2262Hush shell:
2263-----------
2264
2265- similar to Bourne shell, with control structures like
2266  if...then...else...fi, for...do...done; while...do...done,
2267  until...do...done, ...
2268- supports environment ("global") variables (through setenv / saveenv
2269  commands) and local shell variables (through standard shell syntax
2270  "name=value"); only environment variables can be used with "run"
2271  command
2272
2273General rules:
2274--------------
2275
2276(1) If a command line (or an environment variable executed by a "run"
2277    command) contains several commands separated by semicolon, and
2278    one of these commands fails, then the remaining commands will be
2279    executed anyway.
2280
2281(2) If you execute several variables with one call to run (i. e.
2282    calling run with a list af variables as arguments), any failing
2283    command will cause "run" to terminate, i. e. the remaining
2284    variables are not executed.
2285
2286Note for Redundant Ethernet Interfaces:
2287=======================================
2288
2289Some boards come with redundant ethernet interfaces; U-Boot supports
2290such configurations and is capable of automatic selection of a
2291"working" interface when needed. MAC assignment works as follows:
2292
2293Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2294MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2295"eth1addr" (=>eth1), "eth2addr", ...
2296
2297If the network interface stores some valid MAC address (for instance
2298in SROM), this is used as default address if there is NO correspon-
2299ding setting in the environment; if the corresponding environment
2300variable is set, this overrides the settings in the card; that means:
2301
2302o If the SROM has a valid MAC address, and there is no address in the
2303  environment, the SROM's address is used.
2304
2305o If there is no valid address in the SROM, and a definition in the
2306  environment exists, then the value from the environment variable is
2307  used.
2308
2309o If both the SROM and the environment contain a MAC address, and
2310  both addresses are the same, this MAC address is used.
2311
2312o If both the SROM and the environment contain a MAC address, and the
2313  addresses differ, the value from the environment is used and a
2314  warning is printed.
2315
2316o If neither SROM nor the environment contain a MAC address, an error
2317  is raised.
2318
2319
2320Image Formats:
2321==============
2322
2323The "boot" commands of this monitor operate on "image" files which
2324can be basicly anything, preceeded by a special header; see the
2325definitions in include/image.h for details; basicly, the header
2326defines the following image properties:
2327
2328* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2329  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2330  LynxOS, pSOS, QNX, RTEMS, ARTOS;
2331  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, ARTOS, LynxOS).
2332* Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2333  IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2334  Currently supported: ARM, Intel x86, MIPS, NIOS, PowerPC).
2335* Compression Type (uncompressed, gzip, bzip2)
2336* Load Address
2337* Entry Point
2338* Image Name
2339* Image Timestamp
2340
2341The header is marked by a special Magic Number, and both the header
2342and the data portions of the image are secured against corruption by
2343CRC32 checksums.
2344
2345
2346Linux Support:
2347==============
2348
2349Although U-Boot should support any OS or standalone application
2350easily, the main focus has always been on Linux during the design of
2351U-Boot.
2352
2353U-Boot includes many features that so far have been part of some
2354special "boot loader" code within the Linux kernel. Also, any
2355"initrd" images to be used are no longer part of one big Linux image;
2356instead, kernel and "initrd" are separate images. This implementation
2357serves several purposes:
2358
2359- the same features can be used for other OS or standalone
2360  applications (for instance: using compressed images to reduce the
2361  Flash memory footprint)
2362
2363- it becomes much easier to port new Linux kernel versions because
2364  lots of low-level, hardware dependent stuff are done by U-Boot
2365
2366- the same Linux kernel image can now be used with different "initrd"
2367  images; of course this also means that different kernel images can
2368  be run with the same "initrd". This makes testing easier (you don't
2369  have to build a new "zImage.initrd" Linux image when you just
2370  change a file in your "initrd"). Also, a field-upgrade of the
2371  software is easier now.
2372
2373
2374Linux HOWTO:
2375============
2376
2377Porting Linux to U-Boot based systems:
2378---------------------------------------
2379
2380U-Boot cannot save you from doing all the necessary modifications to
2381configure the Linux device drivers for use with your target hardware
2382(no, we don't intend to provide a full virtual machine interface to
2383Linux :-).
2384
2385But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
2386
2387Just make sure your machine specific header file (for instance
2388include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2389Information structure as we define in include/u-boot.h, and make
2390sure that your definition of IMAP_ADDR uses the same value as your
2391U-Boot configuration in CFG_IMMR.
2392
2393
2394Configuring the Linux kernel:
2395-----------------------------
2396
2397No specific requirements for U-Boot. Make sure you have some root
2398device (initial ramdisk, NFS) for your target system.
2399
2400
2401Building a Linux Image:
2402-----------------------
2403
2404With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2405not used. If you use recent kernel source, a new build target
2406"uImage" will exist which automatically builds an image usable by
2407U-Boot. Most older kernels also have support for a "pImage" target,
2408which was introduced for our predecessor project PPCBoot and uses a
2409100% compatible format.
2410
2411Example:
2412
2413	make TQM850L_config
2414	make oldconfig
2415	make dep
2416	make uImage
2417
2418The "uImage" build target uses a special tool (in 'tools/mkimage') to
2419encapsulate a compressed Linux kernel image with header  information,
2420CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2421
2422* build a standard "vmlinux" kernel image (in ELF binary format):
2423
2424* convert the kernel into a raw binary image:
2425
2426	${CROSS_COMPILE}-objcopy -O binary \
2427				 -R .note -R .comment \
2428				 -S vmlinux linux.bin
2429
2430* compress the binary image:
2431
2432	gzip -9 linux.bin
2433
2434* package compressed binary image for U-Boot:
2435
2436	mkimage -A ppc -O linux -T kernel -C gzip \
2437		-a 0 -e 0 -n "Linux Kernel Image" \
2438		-d linux.bin.gz uImage
2439
2440
2441The "mkimage" tool can also be used to create ramdisk images for use
2442with U-Boot, either separated from the Linux kernel image, or
2443combined into one file. "mkimage" encapsulates the images with a 64
2444byte header containing information about target architecture,
2445operating system, image type, compression method, entry points, time
2446stamp, CRC32 checksums, etc.
2447
2448"mkimage" can be called in two ways: to verify existing images and
2449print the header information, or to build new images.
2450
2451In the first form (with "-l" option) mkimage lists the information
2452contained in the header of an existing U-Boot image; this includes
2453checksum verification:
2454
2455	tools/mkimage -l image
2456	  -l ==> list image header information
2457
2458The second form (with "-d" option) is used to build a U-Boot image
2459from a "data file" which is used as image payload:
2460
2461	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2462		      -n name -d data_file image
2463	  -A ==> set architecture to 'arch'
2464	  -O ==> set operating system to 'os'
2465	  -T ==> set image type to 'type'
2466	  -C ==> set compression type 'comp'
2467	  -a ==> set load address to 'addr' (hex)
2468	  -e ==> set entry point to 'ep' (hex)
2469	  -n ==> set image name to 'name'
2470	  -d ==> use image data from 'datafile'
2471
2472Right now, all Linux kernels use the same load address	(0x00000000),
2473but the entry point address depends on the kernel version:
2474
2475- 2.2.x kernels have the entry point at 0x0000000C,
2476- 2.3.x and later kernels have the entry point at 0x00000000.
2477
2478So a typical call to build a U-Boot image would read:
2479
2480	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2481	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2482	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
2483	> examples/uImage.TQM850L
2484	Image Name:   2.4.4 kernel for TQM850L
2485	Created:      Wed Jul 19 02:34:59 2000
2486	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
2487	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
2488	Load Address: 0x00000000
2489	Entry Point:  0x00000000
2490
2491To verify the contents of the image (or check for corruption):
2492
2493	-> tools/mkimage -l examples/uImage.TQM850L
2494	Image Name:   2.4.4 kernel for TQM850L
2495	Created:      Wed Jul 19 02:34:59 2000
2496	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
2497	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
2498	Load Address: 0x00000000
2499	Entry Point:  0x00000000
2500
2501NOTE: for embedded systems where boot time is critical you can trade
2502speed for memory and install an UNCOMPRESSED image instead: this
2503needs more space in Flash, but boots much faster since it does not
2504need to be uncompressed:
2505
2506	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
2507	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2508	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2509	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
2510	> examples/uImage.TQM850L-uncompressed
2511	Image Name:   2.4.4 kernel for TQM850L
2512	Created:      Wed Jul 19 02:34:59 2000
2513	Image Type:   PowerPC Linux Kernel Image (uncompressed)
2514	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
2515	Load Address: 0x00000000
2516	Entry Point:  0x00000000
2517
2518
2519Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2520when your kernel is intended to use an initial ramdisk:
2521
2522	-> tools/mkimage -n 'Simple Ramdisk Image' \
2523	> -A ppc -O linux -T ramdisk -C gzip \
2524	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2525	Image Name:   Simple Ramdisk Image
2526	Created:      Wed Jan 12 14:01:50 2000
2527	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
2528	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
2529	Load Address: 0x00000000
2530	Entry Point:  0x00000000
2531
2532
2533Installing a Linux Image:
2534-------------------------
2535
2536To downloading a U-Boot image over the serial (console) interface,
2537you must convert the image to S-Record format:
2538
2539	objcopy -I binary -O srec examples/image examples/image.srec
2540
2541The 'objcopy' does not understand the information in the U-Boot
2542image header, so the resulting S-Record file will be relative to
2543address 0x00000000. To load it to a given address, you need to
2544specify the target address as 'offset' parameter with the 'loads'
2545command.
2546
2547Example: install the image to address 0x40100000 (which on the
2548TQM8xxL is in the first Flash bank):
2549
2550	=> erase 40100000 401FFFFF
2551
2552	.......... done
2553	Erased 8 sectors
2554
2555	=> loads 40100000
2556	## Ready for S-Record download ...
2557	~>examples/image.srec
2558	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2559	...
2560	15989 15990 15991 15992
2561	[file transfer complete]
2562	[connected]
2563	## Start Addr = 0x00000000
2564
2565
2566You can check the success of the download using the 'iminfo' command;
2567this includes a checksum verification so you  can  be  sure  no	 data
2568corruption happened:
2569
2570	=> imi 40100000
2571
2572	## Checking Image at 40100000 ...
2573	   Image Name:	 2.2.13 for initrd on TQM850L
2574	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
2575	   Data Size:	 335725 Bytes = 327 kB = 0 MB
2576	   Load Address: 00000000
2577	   Entry Point:	 0000000c
2578	   Verifying Checksum ... OK
2579
2580
2581Boot Linux:
2582-----------
2583
2584The "bootm" command is used to boot an application that is stored in
2585memory (RAM or Flash). In case of a Linux kernel image, the contents
2586of the "bootargs" environment variable is passed to the kernel as
2587parameters. You can check and modify this variable using the
2588"printenv" and "setenv" commands:
2589
2590
2591	=> printenv bootargs
2592	bootargs=root=/dev/ram
2593
2594	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2595
2596	=> printenv bootargs
2597	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2598
2599	=> bootm 40020000
2600	## Booting Linux kernel at 40020000 ...
2601	   Image Name:	 2.2.13 for NFS on TQM850L
2602	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
2603	   Data Size:	 381681 Bytes = 372 kB = 0 MB
2604	   Load Address: 00000000
2605	   Entry Point:	 0000000c
2606	   Verifying Checksum ... OK
2607	   Uncompressing Kernel Image ... OK
2608	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
2609	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2610	time_init: decrementer frequency = 187500000/60
2611	Calibrating delay loop... 49.77 BogoMIPS
2612	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2613	...
2614
2615If you want to boot a Linux kernel with initial ram disk, you pass
2616the memory addresses of both the kernel and the initrd image (PPBCOOT
2617format!) to the "bootm" command:
2618
2619	=> imi 40100000 40200000
2620
2621	## Checking Image at 40100000 ...
2622	   Image Name:	 2.2.13 for initrd on TQM850L
2623	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
2624	   Data Size:	 335725 Bytes = 327 kB = 0 MB
2625	   Load Address: 00000000
2626	   Entry Point:	 0000000c
2627	   Verifying Checksum ... OK
2628
2629	## Checking Image at 40200000 ...
2630	   Image Name:	 Simple Ramdisk Image
2631	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
2632	   Data Size:	 566530 Bytes = 553 kB = 0 MB
2633	   Load Address: 00000000
2634	   Entry Point:	 00000000
2635	   Verifying Checksum ... OK
2636
2637	=> bootm 40100000 40200000
2638	## Booting Linux kernel at 40100000 ...
2639	   Image Name:	 2.2.13 for initrd on TQM850L
2640	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
2641	   Data Size:	 335725 Bytes = 327 kB = 0 MB
2642	   Load Address: 00000000
2643	   Entry Point:	 0000000c
2644	   Verifying Checksum ... OK
2645	   Uncompressing Kernel Image ... OK
2646	## Loading RAMDisk Image at 40200000 ...
2647	   Image Name:	 Simple Ramdisk Image
2648	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
2649	   Data Size:	 566530 Bytes = 553 kB = 0 MB
2650	   Load Address: 00000000
2651	   Entry Point:	 00000000
2652	   Verifying Checksum ... OK
2653	   Loading Ramdisk ... OK
2654	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
2655	Boot arguments: root=/dev/ram
2656	time_init: decrementer frequency = 187500000/60
2657	Calibrating delay loop... 49.77 BogoMIPS
2658	...
2659	RAMDISK: Compressed image found at block 0
2660	VFS: Mounted root (ext2 filesystem).
2661
2662	bash#
2663
2664More About U-Boot Image Types:
2665------------------------------
2666
2667U-Boot supports the following image types:
2668
2669   "Standalone Programs" are directly runnable in the environment
2670	provided by U-Boot; it is expected that (if they behave
2671	well) you can continue to work in U-Boot after return from
2672	the Standalone Program.
2673   "OS Kernel Images" are usually images of some Embedded OS which
2674	will take over control completely. Usually these programs
2675	will install their own set of exception handlers, device
2676	drivers, set up the MMU, etc. - this means, that you cannot
2677	expect to re-enter U-Boot except by resetting the CPU.
2678   "RAMDisk Images" are more or less just data blocks, and their
2679	parameters (address, size) are passed to an OS kernel that is
2680	being started.
2681   "Multi-File Images" contain several images, typically an OS
2682	(Linux) kernel image and one or more data images like
2683	RAMDisks. This construct is useful for instance when you want
2684	to boot over the network using BOOTP etc., where the boot
2685	server provides just a single image file, but you want to get
2686	for instance an OS kernel and a RAMDisk image.
2687
2688	"Multi-File Images" start with a list of image sizes, each
2689	image size (in bytes) specified by an "uint32_t" in network
2690	byte order. This list is terminated by an "(uint32_t)0".
2691	Immediately after the terminating 0 follow the images, one by
2692	one, all aligned on "uint32_t" boundaries (size rounded up to
2693	a multiple of 4 bytes).
2694
2695   "Firmware Images" are binary images containing firmware (like
2696	U-Boot or FPGA images) which usually will be programmed to
2697	flash memory.
2698
2699   "Script files" are command sequences that will be executed by
2700	U-Boot's command interpreter; this feature is especially
2701	useful when you configure U-Boot to use a real shell (hush)
2702	as command interpreter.
2703
2704
2705Standalone HOWTO:
2706=================
2707
2708One of the features of U-Boot is that you can dynamically load and
2709run "standalone" applications, which can use some resources of
2710U-Boot like console I/O functions or interrupt services.
2711
2712Two simple examples are included with the sources:
2713
2714"Hello World" Demo:
2715-------------------
2716
2717'examples/hello_world.c' contains a small "Hello World" Demo
2718application; it is automatically compiled when you build U-Boot.
2719It's configured to run at address 0x00040004, so you can play with it
2720like that:
2721
2722	=> loads
2723	## Ready for S-Record download ...
2724	~>examples/hello_world.srec
2725	1 2 3 4 5 6 7 8 9 10 11 ...
2726	[file transfer complete]
2727	[connected]
2728	## Start Addr = 0x00040004
2729
2730	=> go 40004 Hello World! This is a test.
2731	## Starting application at 0x00040004 ...
2732	Hello World
2733	argc = 7
2734	argv[0] = "40004"
2735	argv[1] = "Hello"
2736	argv[2] = "World!"
2737	argv[3] = "This"
2738	argv[4] = "is"
2739	argv[5] = "a"
2740	argv[6] = "test."
2741	argv[7] = "<NULL>"
2742	Hit any key to exit ...
2743
2744	## Application terminated, rc = 0x0
2745
2746Another example, which demonstrates how to register a CPM interrupt
2747handler with the U-Boot code, can be found in 'examples/timer.c'.
2748Here, a CPM timer is set up to generate an interrupt every second.
2749The interrupt service routine is trivial, just printing a '.'
2750character, but this is just a demo program. The application can be
2751controlled by the following keys:
2752
2753	? - print current values og the CPM Timer registers
2754	b - enable interrupts and start timer
2755	e - stop timer and disable interrupts
2756	q - quit application
2757
2758	=> loads
2759	## Ready for S-Record download ...
2760	~>examples/timer.srec
2761	1 2 3 4 5 6 7 8 9 10 11 ...
2762	[file transfer complete]
2763	[connected]
2764	## Start Addr = 0x00040004
2765
2766	=> go 40004
2767	## Starting application at 0x00040004 ...
2768	TIMERS=0xfff00980
2769	Using timer 1
2770	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
2771
2772Hit 'b':
2773	[q, b, e, ?] Set interval 1000000 us
2774	Enabling timer
2775Hit '?':
2776	[q, b, e, ?] ........
2777	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
2778Hit '?':
2779	[q, b, e, ?] .
2780	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
2781Hit '?':
2782	[q, b, e, ?] .
2783	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
2784Hit '?':
2785	[q, b, e, ?] .
2786	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
2787Hit 'e':
2788	[q, b, e, ?] ...Stopping timer
2789Hit 'q':
2790	[q, b, e, ?] ## Application terminated, rc = 0x0
2791
2792
2793Minicom warning:
2794================
2795
2796Over time, many people have reported problems when trying to use the
2797"minicom" terminal emulation program for serial download. I (wd)
2798consider minicom to be broken, and recommend not to use it. Under
2799Unix, I recommend to use C-Kermit for general purpose use (and
2800especially for kermit binary protocol download ("loadb" command), and
2801use "cu" for S-Record download ("loads" command).
2802
2803Nevertheless, if you absolutely want to use it try adding this
2804configuration to your "File transfer protocols" section:
2805
2806	   Name    Program                      Name U/D FullScr IO-Red. Multi
2807	X  kermit  /usr/bin/kermit -i -l %l -s   Y    U    Y       N      N
2808	Y  kermit  /usr/bin/kermit -i -l %l -r   N    D    Y       N      N
2809
2810
2811NetBSD Notes:
2812=============
2813
2814Starting at version 0.9.2, U-Boot supports NetBSD both as host
2815(build U-Boot) and target system (boots NetBSD/mpc8xx).
2816
2817Building requires a cross environment; it is known to work on
2818NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
2819need gmake since the Makefiles are not compatible with BSD make).
2820Note that the cross-powerpc package does not install include files;
2821attempting to build U-Boot will fail because <machine/ansi.h> is
2822missing.  This file has to be installed and patched manually:
2823
2824	# cd /usr/pkg/cross/powerpc-netbsd/include
2825	# mkdir powerpc
2826	# ln -s powerpc machine
2827	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
2828	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
2829
2830Native builds *don't* work due to incompatibilities between native
2831and U-Boot include files.
2832
2833Booting assumes that (the first part of) the image booted is a
2834stage-2 loader which in turn loads and then invokes the kernel
2835proper. Loader sources will eventually appear in the NetBSD source
2836tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
2837meantime, send mail to bruno@exet-ag.de and/or wd@denx.de for
2838details.
2839
2840
2841Implementation Internals:
2842=========================
2843
2844The following is not intended to be a complete description of every
2845implementation detail. However, it should help to understand the
2846inner workings of U-Boot and make it easier to port it to custom
2847hardware.
2848
2849
2850Initial Stack, Global Data:
2851---------------------------
2852
2853The implementation of U-Boot is complicated by the fact that U-Boot
2854starts running out of ROM (flash memory), usually without access to
2855system RAM (because the memory controller is not initialized yet).
2856This means that we don't have writable Data or BSS segments, and BSS
2857is not initialized as zero. To be able to get a C environment working
2858at all, we have to allocate at least a minimal stack. Implementation
2859options for this are defined and restricted by the CPU used: Some CPU
2860models provide on-chip memory (like the IMMR area on MPC8xx and
2861MPC826x processors), on others (parts of) the data cache can be
2862locked as (mis-) used as memory, etc.
2863
2864	Chris Hallinan posted a good summary of  these  issues  to  the
2865	u-boot-users mailing list:
2866
2867	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
2868	From: "Chris Hallinan" <clh@net1plus.com>
2869	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
2870	...
2871
2872	Correct me if I'm wrong, folks, but the way I understand it
2873	is this: Using DCACHE as initial RAM for Stack, etc, does not
2874	require any physical RAM backing up the cache. The cleverness
2875	is that the cache is being used as a temporary supply of
2876	necessary storage before the SDRAM controller is setup. It's
2877	beyond the scope of this list to expain the details, but you
2878	can see how this works by studying the cache architecture and
2879	operation in the architecture and processor-specific manuals.
2880
2881	OCM is On Chip Memory, which I believe the 405GP has 4K. It
2882	is another option for the system designer to use as an
2883	initial stack/ram area prior to SDRAM being available. Either
2884	option should work for you. Using CS 4 should be fine if your
2885	board designers haven't used it for something that would
2886	cause you grief during the initial boot! It is frequently not
2887	used.
2888
2889	CFG_INIT_RAM_ADDR should be somewhere that won't interfere
2890	with your processor/board/system design. The default value
2891	you will find in any recent u-boot distribution in
2892	Walnut405.h should work for you. I'd set it to a value larger
2893	than your SDRAM module. If you have a 64MB SDRAM module, set
2894	it above 400_0000. Just make sure your board has no resources
2895	that are supposed to respond to that address! That code in
2896	start.S has been around a while and should work as is when
2897	you get the config right.
2898
2899	-Chris Hallinan
2900	DS4.COM, Inc.
2901
2902It is essential to remember this, since it has some impact on the C
2903code for the initialization procedures:
2904
2905* Initialized global data (data segment) is read-only. Do not attempt
2906  to write it.
2907
2908* Do not use any unitialized global data (or implicitely initialized
2909  as zero data - BSS segment) at all - this is undefined, initiali-
2910  zation is performed later (when relocating to RAM).
2911
2912* Stack space is very limited. Avoid big data buffers or things like
2913  that.
2914
2915Having only the stack as writable memory limits means we cannot use
2916normal global data to share information beween the code. But it
2917turned out that the implementation of U-Boot can be greatly
2918simplified by making a global data structure (gd_t) available to all
2919functions. We could pass a pointer to this data as argument to _all_
2920functions, but this would bloat the code. Instead we use a feature of
2921the GCC compiler (Global Register Variables) to share the data: we
2922place a pointer (gd) to the global data into a register which we
2923reserve for this purpose.
2924
2925When choosing a register for such a purpose we are restricted by the
2926relevant  (E)ABI  specifications for the current architecture, and by
2927GCC's implementation.
2928
2929For PowerPC, the following registers have specific use:
2930	R1:	stack pointer
2931	R2:	TOC pointer
2932	R3-R4:	parameter passing and return values
2933	R5-R10:	parameter passing
2934	R13:	small data area pointer
2935	R30:	GOT pointer
2936	R31:	frame pointer
2937
2938	(U-Boot also uses R14 as internal GOT pointer.)
2939
2940    ==> U-Boot will use R29 to hold a pointer to the global data
2941
2942    Note: on PPC, we could use a static initializer (since the
2943    address of the global data structure is known at compile time),
2944    but it turned out that reserving a register results in somewhat
2945    smaller code - although the code savings are not that big (on
2946    average for all boards 752 bytes for the whole U-Boot image,
2947    624 text + 127 data).
2948
2949On ARM, the following registers are used:
2950
2951	R0:	function argument word/integer result
2952	R1-R3:	function argument word
2953	R9:	GOT pointer
2954	R10:	stack limit (used only if stack checking if enabled)
2955	R11:	argument (frame) pointer
2956	R12:	temporary workspace
2957	R13:	stack pointer
2958	R14:	link register
2959	R15:	program counter
2960
2961    ==> U-Boot will use R8 to hold a pointer to the global data
2962
2963
2964Memory Management:
2965------------------
2966
2967U-Boot runs in system state and uses physical addresses, i.e. the
2968MMU is not used either for address mapping nor for memory protection.
2969
2970The available memory is mapped to fixed addresses using the memory
2971controller. In this process, a contiguous block is formed for each
2972memory type (Flash, SDRAM, SRAM), even when it consists of several
2973physical memory banks.
2974
2975U-Boot is installed in the first 128 kB of the first Flash bank (on
2976TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
2977booting and sizing and initializing DRAM, the code relocates itself
2978to the upper end of DRAM. Immediately below the U-Boot code some
2979memory is reserved for use by malloc() [see CFG_MALLOC_LEN
2980configuration setting]. Below that, a structure with global Board
2981Info data is placed, followed by the stack (growing downward).
2982
2983Additionally, some exception handler code is copied to the low 8 kB
2984of DRAM (0x00000000 ... 0x00001FFF).
2985
2986So a typical memory configuration with 16 MB of DRAM could look like
2987this:
2988
2989	0x0000 0000	Exception Vector code
2990	      :
2991	0x0000 1FFF
2992	0x0000 2000	Free for Application Use
2993	      :
2994	      :
2995
2996	      :
2997	      :
2998	0x00FB FF20	Monitor Stack (Growing downward)
2999	0x00FB FFAC	Board Info Data and permanent copy of global data
3000	0x00FC 0000	Malloc Arena
3001	      :
3002	0x00FD FFFF
3003	0x00FE 0000	RAM Copy of Monitor Code
3004	...		eventually: LCD or video framebuffer
3005	...		eventually: pRAM (Protected RAM - unchanged by reset)
3006	0x00FF FFFF	[End of RAM]
3007
3008
3009System Initialization:
3010----------------------
3011
3012In the reset configuration, U-Boot starts at the reset entry point
3013(on most PowerPC systens at address 0x00000100). Because of the reset
3014configuration for CS0# this is a mirror of the onboard Flash memory.
3015To be able to re-map memory U-Boot then jumps to its link address.
3016To be able to implement the initialization code in C, a (small!)
3017initial stack is set up in the internal Dual Ported RAM (in case CPUs
3018which provide such a feature like MPC8xx or MPC8260), or in a locked
3019part of the data cache. After that, U-Boot initializes the CPU core,
3020the caches and the SIU.
3021
3022Next, all (potentially) available memory banks are mapped using a
3023preliminary mapping. For example, we put them on 512 MB boundaries
3024(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3025on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3026programmed for SDRAM access. Using the temporary configuration, a
3027simple memory test is run that determines the size of the SDRAM
3028banks.
3029
3030When there is more than one SDRAM bank, and the banks are of
3031different size, the largest is mapped first. For equal size, the first
3032bank (CS2#) is mapped first. The first mapping is always for address
30330x00000000, with any additional banks following immediately to create
3034contiguous memory starting from 0.
3035
3036Then, the monitor installs itself at the upper end of the SDRAM area
3037and allocates memory for use by malloc() and for the global Board
3038Info data; also, the exception vector code is copied to the low RAM
3039pages, and the final stack is set up.
3040
3041Only after this relocation will you have a "normal" C environment;
3042until that you are restricted in several ways, mostly because you are
3043running from ROM, and because the code will have to be relocated to a
3044new address in RAM.
3045
3046
3047U-Boot Porting Guide:
3048----------------------
3049
3050[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3051list, October 2002]
3052
3053
3054int main (int argc, char *argv[])
3055{
3056	sighandler_t no_more_time;
3057
3058	signal (SIGALRM, no_more_time);
3059	alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
3060
3061	if (available_money > available_manpower) {
3062		pay consultant to port U-Boot;
3063		return 0;
3064	}
3065
3066	Download latest U-Boot source;
3067
3068	Subscribe to u-boot-users mailing list;
3069
3070	if (clueless) {
3071		email ("Hi, I am new to U-Boot, how do I get started?");
3072	}
3073
3074	while (learning) {
3075		Read the README file in the top level directory;
3076		Read http://www.denx.de/re/DPLG.html
3077		Read the source, Luke;
3078	}
3079
3080	if (available_money > toLocalCurrency ($2500)) {
3081		Buy a BDI2000;
3082	} else {
3083		Add a lot of aggravation and time;
3084	}
3085
3086	Create your own board support subdirectory;
3087
3088	Create your own board config file;
3089
3090	while (!running) {
3091		do {
3092			Add / modify source code;
3093		} until (compiles);
3094		Debug;
3095		if (clueless)
3096			email ("Hi, I am having problems...");
3097	}
3098	Send patch file to Wolfgang;
3099
3100	return 0;
3101}
3102
3103void no_more_time (int sig)
3104{
3105      hire_a_guru();
3106}
3107
3108
3109Coding Standards:
3110-----------------
3111
3112All contributions to U-Boot should conform to the Linux kernel
3113coding style; see the file "Documentation/CodingStyle" in your Linux
3114kernel source directory.
3115
3116Please note that U-Boot is implemented in C (and to some small parts
3117in Assembler); no C++ is used, so please do not use C++ style
3118comments (//) in your code.
3119
3120Submissions which do not conform to the standards may be returned
3121with a request to reformat the changes.
3122
3123
3124Submitting Patches:
3125-------------------
3126
3127Since the number of patches for U-Boot is growing, we need to
3128establish some rules. Submissions which do not conform to these rules
3129may be rejected, even when they contain important and valuable stuff.
3130
3131
3132When you send a patch, please include the following information with
3133it:
3134
3135* For bug fixes: a description of the bug and how your patch fixes
3136  this bug. Please try to include a way of demonstrating that the
3137  patch actually fixes something.
3138
3139* For new features: a description of the feature and your
3140  implementation.
3141
3142* A CHANGELOG entry as plaintext (separate from the patch)
3143
3144* For major contributions, your entry to the CREDITS file
3145
3146* When you add support for a new board, don't forget to add this
3147  board to the MAKEALL script, too.
3148
3149* If your patch adds new configuration options, don't forget to
3150  document these in the README file.
3151
3152* The patch itself. If you are accessing the CVS repository use "cvs
3153  update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
3154  version of diff does not support these options, then get the latest
3155  version of GNU diff.
3156
3157  The current directory when running this command shall be the top
3158  level directory of the U-Boot source tree, or it's parent directory
3159  (i. e. please make sure that your patch includes sufficient
3160  directory information for the affected files).
3161
3162  We accept patches as plain text, MIME attachments or as uuencoded
3163  gzipped text.
3164
3165* If one logical set of modifications affects or creates several
3166  files, all these changes shall be submitted in a SINGLE patch file.
3167
3168* Changesets that contain different, unrelated modifications shall be
3169  submitted as SEPARATE patches, one patch per changeset.
3170
3171
3172Notes:
3173
3174* Before sending the patch, run the MAKEALL script on your patched
3175  source tree and make sure that no errors or warnings are reported
3176  for any of the boards.
3177
3178* Keep your modifications to the necessary minimum: A patch
3179  containing several unrelated changes or arbitrary reformats will be
3180  returned with a request to re-formatting / split it.
3181
3182* If you modify existing code, make sure that your new code does not
3183  add to the memory footprint of the code ;-) Small is beautiful!
3184  When adding new features, these should compile conditionally only
3185  (using #ifdef), and the resulting code with the new feature
3186  disabled must not need more memory than the old code without your
3187  modification.
3188