xref: /rk3399_rockchip-uboot/README (revision 3d1e8a9d4e40ce17a4fec75ee4055e7ddf6ca1a9)
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- Console Baudrate:
491		CONFIG_BAUDRATE - in bps
492		Select one of the baudrates listed in
493		CFG_BAUDRATE_TABLE, see below.
494
495- Interrupt driven serial port input:
496		CONFIG_SERIAL_SOFTWARE_FIFO
497
498		PPC405GP only.
499		Use an interrupt handler for receiving data on the
500		serial port. It also enables using hardware handshake
501		(RTS/CTS) and UART's built-in FIFO. Set the number of
502		bytes the interrupt driven input buffer should have.
503
504		Set to 0 to disable this feature (this is the default).
505		This will also disable hardware handshake.
506
507- Console UART Number:
508		CONFIG_UART1_CONSOLE
509
510		IBM PPC4xx only.
511		If defined internal UART1 (and not UART0) is used
512		as default U-Boot console.
513
514- Boot Delay:	CONFIG_BOOTDELAY - in seconds
515		Delay before automatically booting the default image;
516		set to -1 to disable autoboot.
517
518		See doc/README.autoboot for these options that
519		work with CONFIG_BOOTDELAY. None are required.
520		CONFIG_BOOT_RETRY_TIME
521		CONFIG_BOOT_RETRY_MIN
522		CONFIG_AUTOBOOT_KEYED
523		CONFIG_AUTOBOOT_PROMPT
524		CONFIG_AUTOBOOT_DELAY_STR
525		CONFIG_AUTOBOOT_STOP_STR
526		CONFIG_AUTOBOOT_DELAY_STR2
527		CONFIG_AUTOBOOT_STOP_STR2
528		CONFIG_ZERO_BOOTDELAY_CHECK
529		CONFIG_RESET_TO_RETRY
530
531- Autoboot Command:
532		CONFIG_BOOTCOMMAND
533		Only needed when CONFIG_BOOTDELAY is enabled;
534		define a command string that is automatically executed
535		when no character is read on the console interface
536		within "Boot Delay" after reset.
537
538		CONFIG_BOOTARGS
539		This can be used to pass arguments to the bootm
540		command. The value of CONFIG_BOOTARGS goes into the
541		environment value "bootargs".
542
543		CONFIG_RAMBOOT and CONFIG_NFSBOOT
544		The value of these goes into the environment as
545		"ramboot" and "nfsboot" respectively, and can be used
546		as a convenience, when switching between booting from
547		ram and nfs.
548
549- Pre-Boot Commands:
550		CONFIG_PREBOOT
551
552		When this option is #defined, the existence of the
553		environment variable "preboot" will be checked
554		immediately before starting the CONFIG_BOOTDELAY
555		countdown and/or running the auto-boot command resp.
556		entering interactive mode.
557
558		This feature is especially useful when "preboot" is
559		automatically generated or modified. For an example
560		see the LWMON board specific code: here "preboot" is
561		modified when the user holds down a certain
562		combination of keys on the (special) keyboard when
563		booting the systems
564
565- Serial Download Echo Mode:
566		CONFIG_LOADS_ECHO
567		If defined to 1, all characters received during a
568		serial download (using the "loads" command) are
569		echoed back. This might be needed by some terminal
570		emulations (like "cu"), but may as well just take
571		time on others. This setting #define's the initial
572		value of the "loads_echo" environment variable.
573
574- Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined)
575		CONFIG_KGDB_BAUDRATE
576		Select one of the baudrates listed in
577		CFG_BAUDRATE_TABLE, see below.
578
579- Monitor Functions:
580		CONFIG_COMMANDS
581		Most monitor functions can be selected (or
582		de-selected) by adjusting the definition of
583		CONFIG_COMMANDS; to select individual functions,
584		#define CONFIG_COMMANDS by "OR"ing any of the
585		following values:
586
587		#define enables commands:
588		-------------------------
589		CFG_CMD_ASKENV	* ask for env variable
590		CFG_CMD_AUTOSCRIPT Autoscript Support
591		CFG_CMD_BDI	  bdinfo
592		CFG_CMD_BEDBUG	  Include BedBug Debugger
593		CFG_CMD_BMP     * BMP support
594		CFG_CMD_BOOTD	  bootd
595		CFG_CMD_CACHE	  icache, dcache
596		CFG_CMD_CONSOLE	  coninfo
597		CFG_CMD_DATE	* support for RTC, date/time...
598		CFG_CMD_DHCP	  DHCP support
599		CFG_CMD_DIAG    * Diagnostics
600		CFG_CMD_DOC     * Disk-On-Chip Support
601		CFG_CMD_DTT       Digital Therm and Thermostat
602		CFG_CMD_ECHO	* echo arguments
603		CFG_CMD_EEPROM	* EEPROM read/write support
604		CFG_CMD_ELF	  bootelf, bootvx
605		CFG_CMD_ENV	  saveenv
606		CFG_CMD_FDC	* Floppy Disk Support
607		CFG_CMD_FAT	  FAT partition support
608		CFG_CMD_FDOS	* Dos diskette Support
609		CFG_CMD_FLASH	  flinfo, erase, protect
610		CFG_CMD_FPGA	  FPGA device initialization support
611		CFG_CMD_HWFLOW  * RTS/CTS hw flow control
612		CFG_CMD_I2C	* I2C serial bus support
613		CFG_CMD_IDE	* IDE harddisk support
614		CFG_CMD_IMI	  iminfo
615		CFG_CMD_IMLS      List all found images
616		CFG_CMD_IMMAP	* IMMR dump support
617		CFG_CMD_IRQ	* irqinfo
618		CFG_CMD_JFFS2   * JFFS2 Support
619		CFG_CMD_KGDB	* kgdb
620		CFG_CMD_LOADB	  loadb
621		CFG_CMD_LOADS	  loads
622		CFG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
623				  loop, mtest
624		CFG_CMD_MISC      Misc functions like sleep etc
625		CFG_CMD_MMC	  MMC memory mapped support
626		CFG_CMD_MII	  MII utility commands
627		CFG_CMD_NAND    * NAND support
628		CFG_CMD_NET	  bootp, tftpboot, rarpboot
629		CFG_CMD_PCI	* pciinfo
630		CFG_CMD_PCMCIA	* PCMCIA support
631		CFG_CMD_PING    * send ICMP ECHO_REQUEST to network host
632		CFG_CMD_PORTIO    Port I/O
633		CFG_CMD_REGINFO * Register dump
634		CFG_CMD_RUN	  run command in env variable
635		CFG_CMD_SAVES     save S record dump
636		CFG_CMD_SCSI	* SCSI Support
637		CFG_CMD_SDRAM   * print SDRAM configuration information
638		CFG_CMD_SETGETDCR Support for DCR Register access (4xx only)
639		CFG_CMD_SPI	* SPI serial bus support
640		CFG_CMD_USB	* USB support
641		CFG_CMD_VFD     * VFD support (TRAB)
642		CFG_CMD_BSP	* Board SPecific functions
643		-----------------------------------------------
644		CFG_CMD_ALL	all
645
646		CFG_CMD_DFL	Default configuration; at the moment
647				this is includes all commands, except
648				the ones marked with "*" in the list
649				above.
650
651		If you don't define CONFIG_COMMANDS it defaults to
652		CFG_CMD_DFL in include/cmd_confdefs.h. A board can
653		override the default settings in the respective
654		include file.
655
656		EXAMPLE: If you want all functions except of network
657		support you can write:
658
659		#define CONFIG_COMMANDS (CFG_CMD_ALL & ~CFG_CMD_NET)
660
661
662	Note:	Don't enable the "icache" and "dcache" commands
663		(configuration option CFG_CMD_CACHE) unless you know
664		what you (and your U-Boot users) are doing. Data
665		cache cannot be enabled on systems like the 8xx or
666		8260 (where accesses to the IMMR region must be
667		uncached), and it cannot be disabled on all other
668		systems where we (mis-) use the data cache to hold an
669		initial stack and some data.
670
671
672		XXX - this list needs to get updated!
673
674- Watchdog:
675		CONFIG_WATCHDOG
676		If this variable is defined, it enables watchdog
677		support. There must be support in the platform specific
678		code for a watchdog. For the 8xx and 8260 CPUs, the
679		SIU Watchdog feature is enabled in the SYPCR
680		register.
681
682- U-Boot Version:
683		CONFIG_VERSION_VARIABLE
684		If this variable is defined, an environment variable
685		named "ver" is created by U-Boot showing the U-Boot
686		version as printed by the "version" command.
687		This variable is readonly.
688
689- Real-Time Clock:
690
691		When CFG_CMD_DATE is selected, the type of the RTC
692		has to be selected, too. Define exactly one of the
693		following options:
694
695		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
696		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
697		CONFIG_RTC_MC146818	- use MC146818 RTC
698		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
699		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
700		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
701		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
702
703		Note that if the RTC uses I2C, then the I2C interface
704		must also be configured. See I2C Support, below.
705
706- Timestamp Support:
707
708		When CONFIG_TIMESTAMP is selected, the timestamp
709		(date and time) of an image is printed by image
710		commands like bootm or iminfo. This option is
711		automatically enabled when you select CFG_CMD_DATE .
712
713- Partition Support:
714		CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
715		and/or CONFIG_ISO_PARTITION
716
717		If IDE or SCSI support	is  enabled  (CFG_CMD_IDE  or
718		CFG_CMD_SCSI) you must configure support for at least
719		one partition type as well.
720
721- IDE Reset method:
722		CONFIG_IDE_RESET_ROUTINE
723
724		Set this to define that instead of a reset Pin, the
725		routine ide_set_reset(int idereset) will be used.
726
727- ATAPI Support:
728		CONFIG_ATAPI
729
730		Set this to enable ATAPI support.
731
732- SCSI Support:
733		At the moment only there is only support for the
734		SYM53C8XX SCSI controller; define
735		CONFIG_SCSI_SYM53C8XX to enable it.
736
737		CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
738		CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
739		CFG_SCSI_MAX_LUN] can be adjusted to define the
740		maximum numbers of LUNs, SCSI ID's and target
741		devices.
742		CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
743
744- NETWORK Support (PCI):
745		CONFIG_E1000
746		Support for Intel 8254x gigabit chips.
747
748		CONFIG_EEPRO100
749		Support for Intel 82557/82559/82559ER chips.
750		Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom
751		write routine for first time initialisation.
752
753		CONFIG_TULIP
754		Support for Digital 2114x chips.
755		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
756		modem chip initialisation (KS8761/QS6611).
757
758		CONFIG_NATSEMI
759		Support for National dp83815 chips.
760
761		CONFIG_NS8382X
762		Support for National dp8382[01] gigabit chips.
763
764- NETWORK Support (other):
765
766		CONFIG_DRIVER_LAN91C96
767		Support for SMSC's LAN91C96 chips.
768
769			CONFIG_LAN91C96_BASE
770			Define this to hold the physical address
771			of the LAN91C96's I/O space
772
773			CONFIG_LAN91C96_USE_32_BIT
774			Define this to enable 32 bit addressing
775
776- USB Support:
777		At the moment only the UHCI host controller is
778		supported (PIP405, MIP405); define
779		CONFIG_USB_UHCI to enable it.
780		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
781		end define CONFIG_USB_STORAGE to enable the USB
782		storage devices.
783		Note:
784		Supported are USB Keyboards and USB Floppy drives
785		(TEAC FD-05PUB).
786
787- MMC Support:
788		The MMC controller on the Intel PXA is supported. To
789		enable this define CONFIG_MMC. The MMC can be
790		accessed from the boot prompt by mapping the device
791		to physical memory similar to flash. Command line is
792		enabled with CFG_CMD_MMC. The MMC driver also works with
793		the FAT fs. This is enabled with CFG_CMD_FAT.
794
795- Keyboard Support:
796		CONFIG_ISA_KEYBOARD
797
798		Define this to enable standard (PC-Style) keyboard
799		support
800
801		CONFIG_I8042_KBD
802		Standard PC keyboard driver with US (is default) and
803		GERMAN key layout (switch via environment 'keymap=de') support.
804		Export function i8042_kbd_init, i8042_tstc and i8042_getc
805		for cfb_console. Supports cursor blinking.
806
807- Video support:
808		CONFIG_VIDEO
809
810		Define this to enable video support (for output to
811		video).
812
813		CONFIG_VIDEO_CT69000
814
815		Enable Chips & Technologies 69000 Video chip
816
817		CONFIG_VIDEO_SMI_LYNXEM
818		Enable Silicon Motion SMI 712/710/810 Video chip
819		Videomode are selected via environment 'videomode' with
820		standard LiLo mode numbers.
821		Following modes are supported  (* is default):
822
823			    800x600  1024x768  1280x1024
824	      256  (8bit)     303*      305       307
825	    65536 (16bit)     314       317       31a
826	16,7 Mill (24bit)     315       318       31b
827		(i.e. setenv videomode 317; saveenv; reset;)
828
829		CONFIG_VIDEO_SED13806
830		Enable Epson SED13806 driver. This driver supports 8bpp
831		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
832		or CONFIG_VIDEO_SED13806_16BPP
833
834- Keyboard Support:
835		CONFIG_KEYBOARD
836
837		Define this to enable a custom keyboard support.
838		This simply calls drv_keyboard_init() which must be
839		defined in your board-specific files.
840		The only board using this so far is RBC823.
841
842- LCD Support:	CONFIG_LCD
843
844		Define this to enable LCD support (for output to LCD
845		display); also select one of the supported displays
846		by defining one of these:
847
848		CONFIG_NEC_NL6648AC33:
849
850			NEC NL6648AC33-18. Active, color, single scan.
851
852		CONFIG_NEC_NL6648BC20
853
854			NEC NL6648BC20-08. 6.5", 640x480.
855			Active, color, single scan.
856
857		CONFIG_SHARP_16x9
858
859			Sharp 320x240. Active, color, single scan.
860			It isn't 16x9, and I am not sure what it is.
861
862		CONFIG_SHARP_LQ64D341
863
864			Sharp LQ64D341 display, 640x480.
865			Active, color, single scan.
866
867		CONFIG_HLD1045
868
869			HLD1045 display, 640x480.
870			Active, color, single scan.
871
872		CONFIG_OPTREX_BW
873
874			Optrex	 CBL50840-2 NF-FW 99 22 M5
875			or
876			Hitachi	 LMG6912RPFC-00T
877			or
878			Hitachi	 SP14Q002
879
880			320x240. Black & white.
881
882		Normally display is black on white background; define
883		CFG_WHITE_ON_BLACK to get it inverted.
884
885- Splash Screen Support: CONFIG_SPLASH_SCREEN
886
887		If this option is set, the environment is checked for
888		a variable "splashimage". If found, the usual display
889		of logo, copyright and system information on the LCD
890		is supressed and the BMP image at the address
891		specified in "splashimage" is loaded instead. The
892		console is redirected to the "nulldev", too. This
893		allows for a "silent" boot where a splash screen is
894		loaded very quickly after power-on.
895
896- Compression support:
897		CONFIG_BZIP2
898
899		If this option is set, support for bzip2 compressed
900		images is included. If not, only uncompressed and gzip
901		compressed images are supported.
902
903		NOTE: the bzip2 algorithm requires a lot of RAM, so
904		the malloc area (as defined by CFG_MALLOC_LEN) should
905		be at least 4MB.
906
907- Ethernet address:
908		CONFIG_ETHADDR
909		CONFIG_ETH2ADDR
910		CONFIG_ETH3ADDR
911
912		Define a default value for ethernet address to use
913		for the respective ethernet interface, in case this
914		is not determined automatically.
915
916- IP address:
917		CONFIG_IPADDR
918
919		Define a default value for the IP address to use for
920		the default ethernet interface, in case this is not
921		determined through e.g. bootp.
922
923- Server IP address:
924		CONFIG_SERVERIP
925
926		Defines a default value for theIP address of a TFTP
927		server to contact when using the "tftboot" command.
928
929- BOOTP Recovery Mode:
930		CONFIG_BOOTP_RANDOM_DELAY
931
932		If you have many targets in a network that try to
933		boot using BOOTP, you may want to avoid that all
934		systems send out BOOTP requests at precisely the same
935		moment (which would happen for instance at recovery
936		from a power failure, when all systems will try to
937		boot, thus flooding the BOOTP server. Defining
938		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
939		inserted before sending out BOOTP requests. The
940		following delays are insterted then:
941
942		1st BOOTP request:	delay 0 ... 1 sec
943		2nd BOOTP request:	delay 0 ... 2 sec
944		3rd BOOTP request:	delay 0 ... 4 sec
945		4th and following
946		BOOTP requests:		delay 0 ... 8 sec
947
948- DHCP Advanced Options:
949		CONFIG_BOOTP_MASK
950
951		You can fine tune the DHCP functionality by adding
952		these flags to the CONFIG_BOOTP_MASK define:
953
954		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
955		serverip from a DHCP server, it is possible that more
956		than one DNS serverip is offered to the client.
957		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
958		serverip will be stored in the additional environment
959		variable "dnsip2". The first DNS serverip is always
960		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
961		is added to the CONFIG_BOOTP_MASK.
962
963		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
964		to do a dynamic update of a DNS server. To do this, they
965		need the hostname of the DHCP requester.
966		If CONFIG_BOOP_SEND_HOSTNAME is added to the
967		CONFIG_BOOTP_MASK, the content of the "hostname"
968		environment variable is passed as option 12 to
969		the DHCP server.
970
971- Status LED:	CONFIG_STATUS_LED
972
973		Several configurations allow to display the current
974		status using a LED. For instance, the LED will blink
975		fast while running U-Boot code, stop blinking as
976		soon as a reply to a BOOTP request was received, and
977		start blinking slow once the Linux kernel is running
978		(supported by a status LED driver in the Linux
979		kernel). Defining CONFIG_STATUS_LED enables this
980		feature in U-Boot.
981
982- CAN Support:	CONFIG_CAN_DRIVER
983
984		Defining CONFIG_CAN_DRIVER enables CAN driver support
985		on those systems that support this (optional)
986		feature, like the TQM8xxL modules.
987
988- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
989
990		These enable I2C serial bus commands. Defining either of
991		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
992		include the appropriate I2C driver for the selected cpu.
993
994		This will allow you to use i2c commands at the u-boot
995		command line (as long as you set CFG_CMD_I2C in
996		CONFIG_COMMANDS) and communicate with i2c based realtime
997		clock chips. See common/cmd_i2c.c for a description of the
998		command line interface.
999
1000		CONFIG_HARD_I2C	selects the CPM hardware driver for I2C.
1001
1002		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1003		bit-banging) driver instead of CPM or similar hardware
1004		support for I2C.
1005
1006		There are several other quantities that must also be
1007		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1008
1009		In both cases you will need to define CFG_I2C_SPEED
1010		to be the frequency (in Hz) at which you wish your i2c bus
1011		to run and CFG_I2C_SLAVE to be the address of this node (ie
1012		the cpu's i2c node address).
1013
1014		Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
1015		sets the cpu up as a master node and so its address should
1016		therefore be cleared to 0 (See, eg, MPC823e User's Manual
1017		p.16-473). So, set CFG_I2C_SLAVE to 0.
1018
1019		That's all that's required for CONFIG_HARD_I2C.
1020
1021		If you use the software i2c interface (CONFIG_SOFT_I2C)
1022		then the following macros need to be defined (examples are
1023		from include/configs/lwmon.h):
1024
1025		I2C_INIT
1026
1027		(Optional). Any commands necessary to enable the I2C
1028		controller or configure ports.
1029
1030		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=  PB_SCL)
1031
1032		I2C_PORT
1033
1034		(Only for MPC8260 CPU). The I/O port to use (the code
1035		assumes both bits are on the same port). Valid values
1036		are 0..3 for ports A..D.
1037
1038		I2C_ACTIVE
1039
1040		The code necessary to make the I2C data line active
1041		(driven).  If the data line is open collector, this
1042		define can be null.
1043
1044		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1045
1046		I2C_TRISTATE
1047
1048		The code necessary to make the I2C data line tri-stated
1049		(inactive).  If the data line is open collector, this
1050		define can be null.
1051
1052		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1053
1054		I2C_READ
1055
1056		Code that returns TRUE if the I2C data line is high,
1057		FALSE if it is low.
1058
1059		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1060
1061		I2C_SDA(bit)
1062
1063		If <bit> is TRUE, sets the I2C data line high. If it
1064		is FALSE, it clears it (low).
1065
1066		eg: #define I2C_SDA(bit) \
1067			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1068			else    immr->im_cpm.cp_pbdat &= ~PB_SDA
1069
1070		I2C_SCL(bit)
1071
1072		If <bit> is TRUE, sets the I2C clock line high. If it
1073		is FALSE, it clears it (low).
1074
1075		eg: #define I2C_SCL(bit) \
1076			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1077			else    immr->im_cpm.cp_pbdat &= ~PB_SCL
1078
1079		I2C_DELAY
1080
1081		This delay is invoked four times per clock cycle so this
1082		controls the rate of data transfer.  The data rate thus
1083		is 1 / (I2C_DELAY * 4). Often defined to be something
1084		like:
1085
1086		#define I2C_DELAY  udelay(2)
1087
1088		CFG_I2C_INIT_BOARD
1089
1090		When a board is reset during an i2c bus transfer
1091		chips might think that the current transfer is still
1092		in progress. On some boards it is possible to access
1093		the i2c SCLK line directly, either by using the
1094		processor pin as a GPIO or by having a second pin
1095		connected to the bus. If this option is defined a
1096		custom i2c_init_board() routine in boards/xxx/board.c
1097		is run early in the boot sequence.
1098
1099- SPI Support:	CONFIG_SPI
1100
1101		Enables SPI driver (so far only tested with
1102		SPI EEPROM, also an instance works with Crystal A/D and
1103		D/As on the SACSng board)
1104
1105		CONFIG_SPI_X
1106
1107		Enables extended (16-bit) SPI EEPROM addressing.
1108		(symmetrical to CONFIG_I2C_X)
1109
1110		CONFIG_SOFT_SPI
1111
1112		Enables a software (bit-bang) SPI driver rather than
1113		using hardware support. This is a general purpose
1114		driver that only requires three general I/O port pins
1115		(two outputs, one input) to function. If this is
1116		defined, the board configuration must define several
1117		SPI configuration items (port pins to use, etc). For
1118		an example, see include/configs/sacsng.h.
1119
1120- FPGA Support: CONFIG_FPGA_COUNT
1121
1122		Specify the number of FPGA devices to support.
1123
1124		CONFIG_FPGA
1125
1126		Used to specify the types of FPGA devices. For
1127		example,
1128		#define CONFIG_FPGA  CFG_XILINX_VIRTEX2
1129
1130		CFG_FPGA_PROG_FEEDBACK
1131
1132		Enable printing of hash marks during FPGA
1133		configuration.
1134
1135		CFG_FPGA_CHECK_BUSY
1136
1137		Enable checks on FPGA configuration interface busy
1138		status by the configuration function. This option
1139		will require a board or device specific function to
1140		be written.
1141
1142		CONFIG_FPGA_DELAY
1143
1144		If defined, a function that provides delays in the
1145		FPGA configuration driver.
1146
1147		CFG_FPGA_CHECK_CTRLC
1148
1149		Allow Control-C to interrupt FPGA configuration
1150
1151		CFG_FPGA_CHECK_ERROR
1152
1153		Check for configuration errors during FPGA bitfile
1154		loading. For example, abort during Virtex II
1155		configuration if the INIT_B line goes low (which
1156		indicated a CRC error).
1157
1158		CFG_FPGA_WAIT_INIT
1159
1160		Maximum time to wait for the INIT_B line to deassert
1161		after PROB_B has been deasserted during a Virtex II
1162		FPGA configuration sequence. The default time is 500 mS.
1163
1164		CFG_FPGA_WAIT_BUSY
1165
1166		Maximum time to wait for BUSY to deassert during
1167		Virtex II FPGA configuration. The default is 5 mS.
1168
1169		CFG_FPGA_WAIT_CONFIG
1170
1171		Time to wait after FPGA configuration. The default is
1172		200 mS.
1173
1174- FPGA Support:	CONFIG_FPGA_COUNT
1175
1176		Specify the number of FPGA devices to support.
1177
1178		CONFIG_FPGA
1179
1180		Used to specify the types of FPGA devices.  For example,
1181		#define CONFIG_FPGA  CFG_XILINX_VIRTEX2
1182
1183		CFG_FPGA_PROG_FEEDBACK
1184
1185		Enable printing of hash marks during FPGA configuration.
1186
1187		CFG_FPGA_CHECK_BUSY
1188
1189		Enable checks on FPGA configuration interface busy
1190		status by the configuration function. This option
1191		will require a board or device specific function to
1192		be written.
1193
1194		CONFIG_FPGA_DELAY
1195
1196		If defined, a function that provides delays in the FPGA
1197		configuration driver.
1198
1199		CFG_FPGA_CHECK_CTRLC
1200		Allow Control-C to interrupt FPGA configuration
1201
1202		CFG_FPGA_CHECK_ERROR
1203
1204		Check for configuration errors during FPGA bitfile
1205		loading. For example, abort during Virtex II
1206		configuration if the INIT_B line goes low (which
1207		indicated a CRC error).
1208
1209		CFG_FPGA_WAIT_INIT
1210
1211		Maximum time to wait for the INIT_B line to deassert
1212		after PROB_B has been deasserted during a Virtex II
1213		FPGA configuration sequence. The default time is 500
1214		mS.
1215
1216		CFG_FPGA_WAIT_BUSY
1217
1218		Maximum time to wait for BUSY to deassert during
1219		Virtex II FPGA configuration. The default is 5 mS.
1220
1221		CFG_FPGA_WAIT_CONFIG
1222
1223		Time to wait after FPGA configuration. The default is
1224		200 mS.
1225
1226- Configuration Management:
1227		CONFIG_IDENT_STRING
1228
1229		If defined, this string will be added to the U-Boot
1230		version information (U_BOOT_VERSION)
1231
1232- Vendor Parameter Protection:
1233
1234		U-Boot considers the values of the environment
1235		variables "serial#" (Board Serial Number) and
1236		"ethaddr" (Ethernet Address) to be parameters that
1237		are set once by the board vendor / manufacturer, and
1238		protects these variables from casual modification by
1239		the user. Once set, these variables are read-only,
1240		and write or delete attempts are rejected. You can
1241		change this behviour:
1242
1243		If CONFIG_ENV_OVERWRITE is #defined in your config
1244		file, the write protection for vendor parameters is
1245		completely disabled. Anybody can change or delete
1246		these parameters.
1247
1248		Alternatively, if you #define _both_ CONFIG_ETHADDR
1249		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1250		ethernet address is installed in the environment,
1251		which can be changed exactly ONCE by the user. [The
1252		serial# is unaffected by this, i. e. it remains
1253		read-only.]
1254
1255- Protected RAM:
1256		CONFIG_PRAM
1257
1258		Define this variable to enable the reservation of
1259		"protected RAM", i. e. RAM which is not overwritten
1260		by U-Boot. Define CONFIG_PRAM to hold the number of
1261		kB you want to reserve for pRAM. You can overwrite
1262		this default value by defining an environment
1263		variable "pram" to the number of kB you want to
1264		reserve. Note that the board info structure will
1265		still show the full amount of RAM. If pRAM is
1266		reserved, a new environment variable "mem" will
1267		automatically be defined to hold the amount of
1268		remaining RAM in a form that can be passed as boot
1269		argument to Linux, for instance like that:
1270
1271			setenv bootargs ... mem=\$(mem)
1272			saveenv
1273
1274		This way you can tell Linux not to use this memory,
1275		either, which results in a memory region that will
1276		not be affected by reboots.
1277
1278		*WARNING* If your board configuration uses automatic
1279		detection of the RAM size, you must make sure that
1280		this memory test is non-destructive. So far, the
1281		following board configurations are known to be
1282		"pRAM-clean":
1283
1284			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1285			HERMES, IP860, RPXlite, LWMON, LANTEC,
1286			PCU_E, FLAGADM, TQM8260
1287
1288- Error Recovery:
1289		CONFIG_PANIC_HANG
1290
1291		Define this variable to stop the system in case of a
1292		fatal error, so that you have to reset it manually.
1293		This is probably NOT a good idea for an embedded
1294		system where you want to system to reboot
1295		automatically as fast as possible, but it may be
1296		useful during development since you can try to debug
1297		the conditions that lead to the situation.
1298
1299		CONFIG_NET_RETRY_COUNT
1300
1301		This variable defines the number of retries for
1302		network operations like ARP, RARP, TFTP, or BOOTP
1303		before giving up the operation. If not defined, a
1304		default value of 5 is used.
1305
1306- Command Interpreter:
1307		CFG_HUSH_PARSER
1308
1309		Define this variable to enable the "hush" shell (from
1310		Busybox) as command line interpreter, thus enabling
1311		powerful command line syntax like
1312		if...then...else...fi conditionals or `&&' and '||'
1313		constructs ("shell scripts").
1314
1315		If undefined, you get the old, much simpler behaviour
1316		with a somewhat smaller memory footprint.
1317
1318
1319		CFG_PROMPT_HUSH_PS2
1320
1321		This defines the secondary prompt string, which is
1322		printed when the command interpreter needs more input
1323		to complete a command. Usually "> ".
1324
1325	Note:
1326
1327		In the current implementation, the local variables
1328		space and global environment variables space are
1329		separated. Local variables are those you define by
1330		simply typing `name=value'. To access a local
1331		variable later on, you have write `$name' or
1332		`${name}'; to execute the contents of a variable
1333		directly type `$name' at the command prompt.
1334
1335		Global environment variables are those you use
1336		setenv/printenv to work with. To run a command stored
1337		in such a variable, you need to use the run command,
1338		and you must not use the '$' sign to access them.
1339
1340		To store commands and special characters in a
1341		variable, please use double quotation marks
1342		surrounding the whole text of the variable, instead
1343		of the backslashes before semicolons and special
1344		symbols.
1345
1346- Default Environment
1347		CONFIG_EXTRA_ENV_SETTINGS
1348
1349		Define this to contain any number of null terminated
1350		strings (variable = value pairs) that will be part of
1351		the default environment compiled into the boot image.
1352
1353		For example, place something like this in your
1354		board's config file:
1355
1356		#define CONFIG_EXTRA_ENV_SETTINGS \
1357			"myvar1=value1\0" \
1358			"myvar2=value2\0"
1359
1360		Warning: This method is based on knowledge about the
1361		internal format how the environment is stored by the
1362		U-Boot code. This is NOT an official, exported
1363		interface! Although it is unlikely that this format
1364		will change soon, there is no guarantee either.
1365		You better know what you are doing here.
1366
1367		Note: overly (ab)use of the default environment is
1368		discouraged. Make sure to check other ways to preset
1369		the environment like the autoscript function or the
1370		boot command first.
1371
1372- DataFlash Support
1373		CONFIG_HAS_DATAFLASH
1374
1375		Defining this option enables DataFlash features and
1376		allows to read/write in Dataflash via the standard
1377		commands cp, md...
1378
1379- Show boot progress
1380		CONFIG_SHOW_BOOT_PROGRESS
1381
1382		Defining this option allows to add some board-
1383		specific code (calling a user-provided function
1384		"show_boot_progress(int)") that enables you to show
1385		the system's boot progress on some display (for
1386		example, some LED's) on your board. At the moment,
1387		the following checkpoints are implemented:
1388
1389  Arg	Where			When
1390    1	common/cmd_bootm.c	before attempting to boot an image
1391   -1	common/cmd_bootm.c	Image header has bad     magic number
1392    2	common/cmd_bootm.c	Image header has correct magic number
1393   -2	common/cmd_bootm.c	Image header has bad     checksum
1394    3	common/cmd_bootm.c	Image header has correct checksum
1395   -3	common/cmd_bootm.c	Image data   has bad     checksum
1396    4	common/cmd_bootm.c	Image data   has correct checksum
1397   -4	common/cmd_bootm.c	Image is for unsupported architecture
1398    5	common/cmd_bootm.c	Architecture check OK
1399   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi, standalone)
1400    6	common/cmd_bootm.c	Image Type check OK
1401   -6	common/cmd_bootm.c	gunzip uncompression error
1402   -7	common/cmd_bootm.c	Unimplemented compression type
1403    7	common/cmd_bootm.c	Uncompression OK
1404   -8	common/cmd_bootm.c	Wrong Image Type (not kernel, multi, standalone)
1405    8	common/cmd_bootm.c	Image Type check OK
1406   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
1407    9	common/cmd_bootm.c	Start initial ramdisk verification
1408  -10	common/cmd_bootm.c	Ramdisk header has bad     magic number
1409  -11	common/cmd_bootm.c	Ramdisk header has bad     checksum
1410   10	common/cmd_bootm.c	Ramdisk header is OK
1411  -12	common/cmd_bootm.c	Ramdisk data   has bad     checksum
1412   11	common/cmd_bootm.c	Ramdisk data   has correct checksum
1413   12	common/cmd_bootm.c	Ramdisk verification complete, start loading
1414  -13	common/cmd_bootm.c	Wrong Image Type (not PPC Linux Ramdisk)
1415   13	common/cmd_bootm.c	Start multifile image verification
1416   14	common/cmd_bootm.c	No initial ramdisk, no multifile, continue.
1417   15	common/cmd_bootm.c	All preparation done, transferring control to OS
1418
1419   -1	common/cmd_doc.c	Bad usage of "doc" command
1420   -1	common/cmd_doc.c	No boot device
1421   -1	common/cmd_doc.c	Unknown Chip ID on boot device
1422   -1	common/cmd_doc.c	Read Error on boot device
1423   -1	common/cmd_doc.c	Image header has bad magic number
1424
1425   -1	common/cmd_ide.c	Bad usage of "ide" command
1426   -1	common/cmd_ide.c	No boot device
1427   -1	common/cmd_ide.c	Unknown boot device
1428   -1	common/cmd_ide.c	Unknown partition table
1429   -1	common/cmd_ide.c	Invalid partition type
1430   -1	common/cmd_ide.c	Read Error on boot device
1431   -1	common/cmd_ide.c	Image header has bad magic number
1432
1433   -1	common/cmd_nand.c	Bad usage of "nand" command
1434   -1	common/cmd_nand.c	No boot device
1435   -1	common/cmd_nand.c	Unknown Chip ID on boot device
1436   -1	common/cmd_nand.c	Read Error on boot device
1437   -1	common/cmd_nand.c	Image header has bad magic number
1438
1439   -1	common/env_common.c     Environment has a bad CRC, using default
1440
1441
1442Modem Support:
1443--------------
1444
1445[so far only for SMDK2400 and TRAB boards]
1446
1447- Modem support endable:
1448		CONFIG_MODEM_SUPPORT
1449
1450- RTS/CTS Flow control enable:
1451		CONFIG_HWFLOW
1452
1453- Modem debug support:
1454		CONFIG_MODEM_SUPPORT_DEBUG
1455
1456		Enables debugging stuff (char screen[1024], dbg())
1457		for modem support. Useful only with BDI2000.
1458
1459- General:
1460
1461		In the target system modem support is enabled when a
1462		specific key (key combination) is pressed during
1463		power-on. Otherwise U-Boot will boot normally
1464		(autoboot). The key_pressed() fuction is called from
1465		board_init(). Currently key_pressed() is a dummy
1466		function, returning 1 and thus enabling modem
1467		initialization.
1468
1469		If there are no modem init strings in the
1470		environment, U-Boot proceed to autoboot; the
1471		previous output (banner, info printfs) will be
1472		supressed, though.
1473
1474		See also: doc/README.Modem
1475
1476
1477Configuration Settings:
1478-----------------------
1479
1480- CFG_LONGHELP: Defined when you want long help messages included;
1481		undefine this when you're short of memory.
1482
1483- CFG_PROMPT:	This is what U-Boot prints on the console to
1484		prompt for user input.
1485
1486- CFG_CBSIZE:	Buffer size for input from the Console
1487
1488- CFG_PBSIZE:	Buffer size for Console output
1489
1490- CFG_MAXARGS:	max. Number of arguments accepted for monitor commands
1491
1492- CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1493		the application (usually a Linux kernel) when it is
1494		booted
1495
1496- CFG_BAUDRATE_TABLE:
1497		List of legal baudrate settings for this board.
1498
1499- CFG_CONSOLE_INFO_QUIET
1500		Suppress display of console information at boot.
1501
1502- CFG_CONSOLE_IS_IN_ENV
1503		If the board specific function
1504			extern int overwrite_console (void);
1505		returns 1, the stdin, stderr and stdout are switched to the
1506		serial port, else the settings in the environment are used.
1507
1508- CFG_CONSOLE_OVERWRITE_ROUTINE
1509		Enable the call to overwrite_console().
1510
1511- CFG_CONSOLE_ENV_OVERWRITE
1512		Enable overwrite of previous console environment settings.
1513
1514- CFG_MEMTEST_START, CFG_MEMTEST_END:
1515		Begin and End addresses of the area used by the
1516		simple memory test.
1517
1518- CFG_ALT_MEMTEST:
1519		Enable an alternate, more extensive memory test.
1520
1521- CFG_MEMTEST_SCRATCH:
1522		Scratch address used by the alternate memory test
1523		You only need to set this if address zero isn't writeable
1524
1525- CFG_TFTP_LOADADDR:
1526		Default load address for network file downloads
1527
1528- CFG_LOADS_BAUD_CHANGE:
1529		Enable temporary baudrate change while serial download
1530
1531- CFG_SDRAM_BASE:
1532		Physical start address of SDRAM. _Must_ be 0 here.
1533
1534- CFG_MBIO_BASE:
1535		Physical start address of Motherboard I/O (if using a
1536		Cogent motherboard)
1537
1538- CFG_FLASH_BASE:
1539		Physical start address of Flash memory.
1540
1541- CFG_MONITOR_BASE:
1542		Physical start address of boot monitor code (set by
1543		make config files to be same as the text base address
1544		(TEXT_BASE) used when linking) - same as
1545		CFG_FLASH_BASE when booting from flash.
1546
1547- CFG_MONITOR_LEN:
1548		Size of memory reserved for monitor code, used to
1549		determine _at_compile_time_ (!) if the environment is
1550		embedded within the U-Boot image, or in a separate
1551		flash sector.
1552
1553- CFG_MALLOC_LEN:
1554		Size of DRAM reserved for malloc() use.
1555
1556- CFG_BOOTMAPSZ:
1557		Maximum size of memory mapped by the startup code of
1558		the Linux kernel; all data that must be processed by
1559		the Linux kernel (bd_info, boot arguments, eventually
1560		initrd image) must be put below this limit.
1561
1562- CFG_MAX_FLASH_BANKS:
1563		Max number of Flash memory banks
1564
1565- CFG_MAX_FLASH_SECT:
1566		Max number of sectors on a Flash chip
1567
1568- CFG_FLASH_ERASE_TOUT:
1569		Timeout for Flash erase operations (in ms)
1570
1571- CFG_FLASH_WRITE_TOUT:
1572		Timeout for Flash write operations (in ms)
1573
1574- CFG_FLASH_LOCK_TOUT
1575		Timeout for Flash set sector lock bit operation (in ms)
1576
1577- CFG_FLASH_UNLOCK_TOUT
1578		Timeout for Flash clear lock bits operation (in ms)
1579
1580- CFG_FLASH_PROTECTION
1581		If defined, hardware flash sectors protection is used
1582		instead of U-Boot software protection.
1583
1584- CFG_DIRECT_FLASH_TFTP:
1585
1586		Enable TFTP transfers directly to flash memory;
1587		without this option such a download has to be
1588		performed in two steps: (1) download to RAM, and (2)
1589		copy from RAM to flash.
1590
1591		The two-step approach is usually more reliable, since
1592		you can check if the download worked before you erase
1593		the flash, but in some situations (when sytem RAM is
1594		too limited to allow for a tempory copy of the
1595		downloaded image) this option may be very useful.
1596
1597- CFG_FLASH_CFI:
1598		Define if the flash driver uses extra elements in the
1599		common flash structure for storing flash geometry
1600
1601- CFG_RX_ETH_BUFFER:
1602		Defines the number of ethernet receive buffers. On some
1603		ethernet controllers it is recommended to set this value
1604		to 8 or even higher (EEPRO100 or 405 EMAC), since all
1605		buffers can be full shortly after enabling the interface
1606		on high ethernet traffic.
1607		Defaults to 4 if not defined.
1608
1609The following definitions that deal with the placement and management
1610of environment data (variable area); in general, we support the
1611following configurations:
1612
1613- CFG_ENV_IS_IN_FLASH:
1614
1615	Define this if the environment is in flash memory.
1616
1617	a) The environment occupies one whole flash sector, which is
1618	   "embedded" in the text segment with the U-Boot code. This
1619	   happens usually with "bottom boot sector" or "top boot
1620	   sector" type flash chips, which have several smaller
1621	   sectors at the start or the end. For instance, such a
1622	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
1623	   such a case you would place the environment in one of the
1624	   4 kB sectors - with U-Boot code before and after it. With
1625	   "top boot sector" type flash chips, you would put the
1626	   environment in one of the last sectors, leaving a gap
1627	   between U-Boot and the environment.
1628
1629	- CFG_ENV_OFFSET:
1630
1631	   Offset of environment data (variable area) to the
1632	   beginning of flash memory; for instance, with bottom boot
1633	   type flash chips the second sector can be used: the offset
1634	   for this sector is given here.
1635
1636	   CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
1637
1638	- CFG_ENV_ADDR:
1639
1640	   This is just another way to specify the start address of
1641	   the flash sector containing the environment (instead of
1642	   CFG_ENV_OFFSET).
1643
1644	- CFG_ENV_SECT_SIZE:
1645
1646	   Size of the sector containing the environment.
1647
1648
1649	b) Sometimes flash chips have few, equal sized, BIG sectors.
1650	   In such a case you don't want to spend a whole sector for
1651	   the environment.
1652
1653	- CFG_ENV_SIZE:
1654
1655	   If you use this in combination with CFG_ENV_IS_IN_FLASH
1656	   and CFG_ENV_SECT_SIZE, you can specify to use only a part
1657	   of this flash sector for the environment. This saves
1658	   memory for the RAM copy of the environment.
1659
1660	   It may also save flash memory if you decide to use this
1661	   when your environment is "embedded" within U-Boot code,
1662	   since then the remainder of the flash sector could be used
1663	   for U-Boot code. It should be pointed out that this is
1664	   STRONGLY DISCOURAGED from a robustness point of view:
1665	   updating the environment in flash makes it always
1666	   necessary to erase the WHOLE sector. If something goes
1667	   wrong before the contents has been restored from a copy in
1668	   RAM, your target system will be dead.
1669
1670	- CFG_ENV_ADDR_REDUND
1671	  CFG_ENV_SIZE_REDUND
1672
1673	   These settings describe a second storage area used to hold
1674	   a redundand copy of the environment data, so that there is
1675	   a valid backup copy in case there is a power failure during
1676	   a "saveenv" operation.
1677
1678BE CAREFUL! Any changes to the flash layout, and some changes to the
1679source code will make it necessary to adapt <board>/u-boot.lds*
1680accordingly!
1681
1682
1683- CFG_ENV_IS_IN_NVRAM:
1684
1685	Define this if you have some non-volatile memory device
1686	(NVRAM, battery buffered SRAM) which you want to use for the
1687	environment.
1688
1689	- CFG_ENV_ADDR:
1690	- CFG_ENV_SIZE:
1691
1692	  These two #defines are used to determin the memory area you
1693	  want to use for environment. It is assumed that this memory
1694	  can just be read and written to, without any special
1695	  provision.
1696
1697BE CAREFUL! The first access to the environment happens quite early
1698in U-Boot initalization (when we try to get the setting of for the
1699console baudrate). You *MUST* have mappend your NVRAM area then, or
1700U-Boot will hang.
1701
1702Please note that even with NVRAM we still use a copy of the
1703environment in RAM: we could work on NVRAM directly, but we want to
1704keep settings there always unmodified except somebody uses "saveenv"
1705to save the current settings.
1706
1707
1708- CFG_ENV_IS_IN_EEPROM:
1709
1710	Use this if you have an EEPROM or similar serial access
1711	device and a driver for it.
1712
1713	- CFG_ENV_OFFSET:
1714	- CFG_ENV_SIZE:
1715
1716	  These two #defines specify the offset and size of the
1717	  environment area within the total memory of your EEPROM.
1718
1719	- CFG_I2C_EEPROM_ADDR:
1720	  If defined, specified the chip address of the EEPROM device.
1721	  The default address is zero.
1722
1723	- CFG_EEPROM_PAGE_WRITE_BITS:
1724	  If defined, the number of bits used to address bytes in a
1725	  single page in the EEPROM device.  A 64 byte page, for example
1726	  would require six bits.
1727
1728	- CFG_EEPROM_PAGE_WRITE_DELAY_MS:
1729	  If defined, the number of milliseconds to delay between
1730	  page writes.  The default is zero milliseconds.
1731
1732	- CFG_I2C_EEPROM_ADDR_LEN:
1733	  The length in bytes of the EEPROM memory array address.  Note
1734	  that this is NOT the chip address length!
1735
1736	- CFG_EEPROM_SIZE:
1737	  The size in bytes of the EEPROM device.
1738
1739
1740- CFG_SPI_INIT_OFFSET
1741
1742	Defines offset to the initial SPI buffer area in DPRAM. The
1743	area is used at an early stage (ROM part) if the environment
1744	is configured to reside in the SPI EEPROM: We need a 520 byte
1745	scratch DPRAM area. It is used between the two initialization
1746	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
1747	to be a good choice since it makes it far enough from the
1748	start of the data area as well as from the stack pointer.
1749
1750Please note that the environment is read-only as long as the monitor
1751has been relocated to RAM and a RAM copy of the environment has been
1752created; also, when using EEPROM you will have to use getenv_r()
1753until then to read environment variables.
1754
1755The environment is protected by a CRC32 checksum. Before the monitor
1756is relocated into RAM, as a result of a bad CRC you will be working
1757with the compiled-in default environment - *silently*!!! [This is
1758necessary, because the first environment variable we need is the
1759"baudrate" setting for the console - if we have a bad CRC, we don't
1760have any device yet where we could complain.]
1761
1762Note: once the monitor has been relocated, then it will complain if
1763the default environment is used; a new CRC is computed as soon as you
1764use the "saveenv" command to store a valid environment.
1765
1766- CFG_FAULT_ECHO_LINK_DOWN:
1767		Echo the inverted Ethernet link state to the fault LED.
1768
1769		Note: If this option is active, then CFG_FAULT_MII_ADDR
1770		      also needs to be defined.
1771
1772- CFG_FAULT_MII_ADDR:
1773		MII address of the PHY to check for the Ethernet link state.
1774
1775Low Level (hardware related) configuration options:
1776---------------------------------------------------
1777
1778- CFG_CACHELINE_SIZE:
1779		Cache Line Size of the CPU.
1780
1781- CFG_DEFAULT_IMMR:
1782		Default address of the IMMR after system reset.
1783
1784		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
1785		and RPXsuper) to be able to adjust the position of
1786		the IMMR register after a reset.
1787
1788- Floppy Disk Support:
1789		CFG_FDC_DRIVE_NUMBER
1790
1791		the default drive number (default value 0)
1792
1793		CFG_ISA_IO_STRIDE
1794
1795		defines the spacing between fdc chipset registers
1796		(default value 1)
1797
1798		CFG_ISA_IO_OFFSET
1799
1800		defines the offset of register from address. It
1801		depends on which part of the data bus is connected to
1802		the fdc chipset. (default value 0)
1803
1804		If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
1805		CFG_FDC_DRIVE_NUMBER are undefined, they take their
1806		default value.
1807
1808		if CFG_FDC_HW_INIT is defined, then the function
1809		fdc_hw_init() is called at the beginning of the FDC
1810		setup. fdc_hw_init() must be provided by the board
1811		source code. It is used to make hardware dependant
1812		initializations.
1813
1814- CFG_IMMR:	Physical address of the Internal Memory Mapped
1815		Register; DO NOT CHANGE! (11-4)
1816		[MPC8xx systems only]
1817
1818- CFG_INIT_RAM_ADDR:
1819
1820		Start address of memory area that can be used for
1821		initial data and stack; please note that this must be
1822		writable memory that is working WITHOUT special
1823		initialization, i. e. you CANNOT use normal RAM which
1824		will become available only after programming the
1825		memory controller and running certain initialization
1826		sequences.
1827
1828		U-Boot uses the following memory types:
1829		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
1830		- MPC824X: data cache
1831		- PPC4xx:  data cache
1832
1833- CFG_GBL_DATA_OFFSET:
1834
1835		Offset of the initial data structure in the memory
1836		area defined by CFG_INIT_RAM_ADDR. Usually
1837		CFG_GBL_DATA_OFFSET is chosen such that the initial
1838		data is located at the end of the available space
1839		(sometimes written as (CFG_INIT_RAM_END -
1840		CFG_INIT_DATA_SIZE), and the initial stack is just
1841		below that area (growing from (CFG_INIT_RAM_ADDR +
1842		CFG_GBL_DATA_OFFSET) downward.
1843
1844	Note:
1845		On the MPC824X (or other systems that use the data
1846		cache for initial memory) the address chosen for
1847		CFG_INIT_RAM_ADDR is basically arbitrary - it must
1848		point to an otherwise UNUSED address space between
1849		the top of RAM and the start of the PCI space.
1850
1851- CFG_SIUMCR:	SIU Module Configuration (11-6)
1852
1853- CFG_SYPCR:	System Protection Control (11-9)
1854
1855- CFG_TBSCR:	Time Base Status and Control (11-26)
1856
1857- CFG_PISCR:	Periodic Interrupt Status and Control (11-31)
1858
1859- CFG_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
1860
1861- CFG_SCCR:	System Clock and reset Control Register (15-27)
1862
1863- CFG_OR_TIMING_SDRAM:
1864		SDRAM timing
1865
1866- CFG_MAMR_PTA:
1867		periodic timer for refresh
1868
1869- CFG_DER:	Debug Event Register (37-47)
1870
1871- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
1872  CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
1873  CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
1874  CFG_BR1_PRELIM:
1875		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
1876
1877- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
1878  CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
1879  CFG_OR3_PRELIM, CFG_BR3_PRELIM:
1880		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
1881
1882- CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
1883  CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
1884		Machine Mode Register and Memory Periodic Timer
1885		Prescaler definitions (SDRAM timing)
1886
1887- CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
1888		enable I2C microcode relocation patch (MPC8xx);
1889		define relocation offset in DPRAM [DSP2]
1890
1891- CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
1892		enable SPI microcode relocation patch (MPC8xx);
1893		define relocation offset in DPRAM [SCC4]
1894
1895- CFG_USE_OSCCLK:
1896		Use OSCM clock mode on MBX8xx board. Be careful,
1897		wrong setting might damage your board. Read
1898		doc/README.MBX before setting this variable!
1899
1900- CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
1901		Offset of the bootmode word in DPRAM used by post
1902		(Power On Self Tests). This definition overrides
1903		#define'd default value in commproc.h resp.
1904		cpm_8260.h.
1905
1906- CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
1907  CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
1908  CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
1909  CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
1910  CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
1911  CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
1912  CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
1913  CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
1914		Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
1915
1916Building the Software:
1917======================
1918
1919Building U-Boot has been tested in native PPC environments (on a
1920PowerBook G3 running LinuxPPC 2000) and in cross environments
1921(running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
1922NetBSD 1.5 on x86).
1923
1924If you are not using a native PPC environment, it is assumed that you
1925have the GNU cross compiling tools available in your path and named
1926with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
1927you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
1928the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
1929change it to:
1930
1931	CROSS_COMPILE = ppc_4xx-
1932
1933
1934U-Boot is intended to be  simple  to  build.  After  installing  the
1935sources	 you must configure U-Boot for one specific board type. This
1936is done by typing:
1937
1938	make NAME_config
1939
1940where "NAME_config" is the name of one of the existing
1941configurations; the following names are supported:
1942
1943    ADCIOP_config	  GTH_config		TQM850L_config
1944    ADS860_config	  IP860_config		TQM855L_config
1945    AR405_config	  IVML24_config		TQM860L_config
1946    CANBT_config	  IVMS8_config		WALNUT405_config
1947    CPCI405_config	  LANTEC_config		cogent_common_config
1948    CPCIISER4_config	  MBX_config		cogent_mpc8260_config
1949    CU824_config	  MBX860T_config	cogent_mpc8xx_config
1950    ESTEEM192E_config	  RPXlite_config	hermes_config
1951    ETX094_config	  RPXsuper_config	hymod_config
1952    FADS823_config	  SM850_config		lwmon_config
1953    FADS850SAR_config	  SPD823TS_config	pcu_e_config
1954    FADS860T_config	  SXNI855T_config	rsdproto_config
1955    FPS850L_config	  Sandpoint8240_config	sbc8260_config
1956    GENIETV_config	  TQM823L_config	PIP405_config
1957    GEN860T_config	  EBONY_config		FPS860L_config
1958    ELPT860_config	  cmi_mpc5xx_config	NETVIA_config
1959    at91rm9200dk_config	  omap1510inn_config	MPC8260ADS_config
1960    omap1610inn_config	  ZPC1900_config	MPC8540ADS_config
1961    MPC8560ADS_config
1962
1963Note: for some board special configuration names may exist; check  if
1964      additional  information is available from the board vendor; for
1965      instance, the TQM8xxL systems run normally at 50 MHz and use  a
1966      SCC  for	10baseT	 ethernet; there are also systems with 80 MHz
1967      CPU clock, and an optional Fast Ethernet	module	is  available
1968      for  CPU's  with FEC. You can select such additional "features"
1969      when chosing the configuration, i. e.
1970
1971      make TQM860L_config
1972	- will configure for a plain TQM860L, i. e. 50MHz, no FEC
1973
1974      make TQM860L_FEC_config
1975	- will configure for a TQM860L at 50MHz with FEC for ethernet
1976
1977      make TQM860L_80MHz_config
1978	- will configure for a TQM860L at 80 MHz, with normal 10baseT
1979	  interface
1980
1981      make TQM860L_FEC_80MHz_config
1982	- will configure for a TQM860L at 80 MHz with FEC for ethernet
1983
1984      make TQM823L_LCD_config
1985	- will configure for a TQM823L with U-Boot console on LCD
1986
1987      make TQM823L_LCD_80MHz_config
1988	- will configure for a TQM823L at 80 MHz with U-Boot console on LCD
1989
1990      etc.
1991
1992
1993Finally, type "make all", and you should get some working U-Boot
1994images ready for download to / installation on your system:
1995
1996- "u-boot.bin" is a raw binary image
1997- "u-boot" is an image in ELF binary format
1998- "u-boot.srec" is in Motorola S-Record format
1999
2000
2001Please be aware that the Makefiles assume you are using GNU make, so
2002for instance on NetBSD you might need to use "gmake" instead of
2003native "make".
2004
2005
2006If the system board that you have is not listed, then you will need
2007to port U-Boot to your hardware platform. To do this, follow these
2008steps:
2009
20101.  Add a new configuration option for your board to the toplevel
2011    "Makefile" and to the "MAKEALL" script, using the existing
2012    entries as examples. Note that here and at many other places
2013    boards and other names are listed in alphabetical sort order. Please
2014    keep this order.
20152.  Create a new directory to hold your board specific code. Add any
2016    files you need. In your board directory, you will need at least
2017    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
20183.  Create a new configuration file "include/configs/<board>.h" for
2019    your board
20203.  If you're porting U-Boot to a new CPU, then also create a new
2021    directory to hold your CPU specific code. Add any files you need.
20224.  Run "make <board>_config" with your new name.
20235.  Type "make", and you should get a working "u-boot.srec" file
2024    to be installed on your target system.
20256.  Debug and solve any problems that might arise.
2026    [Of course, this last step is much harder than it sounds.]
2027
2028
2029Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2030==============================================================
2031
2032If you have modified U-Boot sources (for instance added a new	board
2033or  support  for  new  devices,	 a new CPU, etc.) you are expected to
2034provide feedback to the other developers. The feedback normally takes
2035the form of a "patch", i. e. a context diff against a certain (latest
2036official or latest in CVS) version of U-Boot sources.
2037
2038But before you submit such a patch, please verify that	your  modifi-
2039cation	did not break existing code. At least make sure that *ALL* of
2040the supported boards compile WITHOUT ANY compiler warnings. To do so,
2041just run the "MAKEALL" script, which will configure and build U-Boot
2042for ALL supported system. Be warned, this will take a while. You  can
2043select	which  (cross)	compiler  to use by passing a `CROSS_COMPILE'
2044environment variable to the script, i. e. to use the cross tools from
2045MontaVista's Hard Hat Linux you can type
2046
2047	CROSS_COMPILE=ppc_8xx- MAKEALL
2048
2049or to build on a native PowerPC system you can type
2050
2051	CROSS_COMPILE=' ' MAKEALL
2052
2053See also "U-Boot Porting Guide" below.
2054
2055
2056Monitor Commands - Overview:
2057============================
2058
2059go	- start application at address 'addr'
2060run	- run commands in an environment variable
2061bootm	- boot application image from memory
2062bootp	- boot image via network using BootP/TFTP protocol
2063tftpboot- boot image via network using TFTP protocol
2064	       and env variables "ipaddr" and "serverip"
2065	       (and eventually "gatewayip")
2066rarpboot- boot image via network using RARP/TFTP protocol
2067diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
2068loads	- load S-Record file over serial line
2069loadb	- load binary file over serial line (kermit mode)
2070md	- memory display
2071mm	- memory modify (auto-incrementing)
2072nm	- memory modify (constant address)
2073mw	- memory write (fill)
2074cp	- memory copy
2075cmp	- memory compare
2076crc32	- checksum calculation
2077imd     - i2c memory display
2078imm     - i2c memory modify (auto-incrementing)
2079inm     - i2c memory modify (constant address)
2080imw     - i2c memory write (fill)
2081icrc32  - i2c checksum calculation
2082iprobe  - probe to discover valid I2C chip addresses
2083iloop   - infinite loop on address range
2084isdram  - print SDRAM configuration information
2085sspi    - SPI utility commands
2086base	- print or set address offset
2087printenv- print environment variables
2088setenv	- set environment variables
2089saveenv - save environment variables to persistent storage
2090protect - enable or disable FLASH write protection
2091erase	- erase FLASH memory
2092flinfo	- print FLASH memory information
2093bdinfo	- print Board Info structure
2094iminfo	- print header information for application image
2095coninfo - print console devices and informations
2096ide	- IDE sub-system
2097loop	- infinite loop on address range
2098mtest	- simple RAM test
2099icache	- enable or disable instruction cache
2100dcache	- enable or disable data cache
2101reset	- Perform RESET of the CPU
2102echo	- echo args to console
2103version - print monitor version
2104help	- print online help
2105?	- alias for 'help'
2106
2107
2108Monitor Commands - Detailed Description:
2109========================================
2110
2111TODO.
2112
2113For now: just type "help <command>".
2114
2115
2116Environment Variables:
2117======================
2118
2119U-Boot supports user configuration using Environment Variables which
2120can be made persistent by saving to Flash memory.
2121
2122Environment Variables are set using "setenv", printed using
2123"printenv", and saved to Flash using "saveenv". Using "setenv"
2124without a value can be used to delete a variable from the
2125environment. As long as you don't save the environment you are
2126working with an in-memory copy. In case the Flash area containing the
2127environment is erased by accident, a default environment is provided.
2128
2129Some configuration options can be set using Environment Variables:
2130
2131  baudrate	- see CONFIG_BAUDRATE
2132
2133  bootdelay	- see CONFIG_BOOTDELAY
2134
2135  bootcmd	- see CONFIG_BOOTCOMMAND
2136
2137  bootargs	- Boot arguments when booting an RTOS image
2138
2139  bootfile	- Name of the image to load with TFTP
2140
2141  autoload	- if set to "no" (any string beginning with 'n'),
2142		  "bootp" will just load perform a lookup of the
2143		  configuration from the BOOTP server, but not try to
2144		  load any image using TFTP
2145
2146  autostart	- if set to "yes", an image loaded using the "bootp",
2147		  "rarpboot", "tftpboot" or "diskboot" commands will
2148		  be automatically started (by internally calling
2149		  "bootm")
2150
2151		  If set to "no", a standalone image passed to the
2152		  "bootm" command will be copied to the load address
2153		  (and eventually uncompressed), but NOT be started.
2154		  This can be used to load and uncompress arbitrary
2155		  data.
2156
2157  initrd_high	- restrict positioning of initrd images:
2158		  If this variable is not set, initrd images will be
2159		  copied to the highest possible address in RAM; this
2160		  is usually what you want since it allows for
2161		  maximum initrd size. If for some reason you want to
2162		  make sure that the initrd image is loaded below the
2163		  CFG_BOOTMAPSZ limit, you can set this environment
2164		  variable to a value of "no" or "off" or "0".
2165		  Alternatively, you can set it to a maximum upper
2166		  address to use (U-Boot will still check that it
2167		  does not overwrite the U-Boot stack and data).
2168
2169		  For instance, when you have a system with 16 MB
2170		  RAM, and want to reserve 4 MB from use by Linux,
2171		  you can do this by adding "mem=12M" to the value of
2172		  the "bootargs" variable. However, now you must make
2173		  sure that the initrd image is placed in the first
2174		  12 MB as well - this can be done with
2175
2176		  setenv initrd_high 00c00000
2177
2178		  If you set initrd_high to 0xFFFFFFFF, this is an
2179		  indication to U-Boot that all addresses are legal
2180		  for the Linux kernel, including addresses in flash
2181		  memory. In this case U-Boot will NOT COPY the
2182		  ramdisk at all. This may be useful to reduce the
2183		  boot time on your system, but requires that this
2184		  feature is supported by your Linux kernel.
2185
2186  ipaddr	- IP address; needed for tftpboot command
2187
2188  loadaddr	- Default load address for commands like "bootp",
2189		  "rarpboot", "tftpboot", "loadb" or "diskboot"
2190
2191  loads_echo	- see CONFIG_LOADS_ECHO
2192
2193  serverip	- TFTP server IP address; needed for tftpboot command
2194
2195  bootretry	- see CONFIG_BOOT_RETRY_TIME
2196
2197  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
2198
2199  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
2200
2201
2202The following environment variables may be used and automatically
2203updated by the network boot commands ("bootp" and "rarpboot"),
2204depending the information provided by your boot server:
2205
2206  bootfile	- see above
2207  dnsip		- IP address of your Domain Name Server
2208  dnsip2	- IP address of your secondary Domain Name Server
2209  gatewayip	- IP address of the Gateway (Router) to use
2210  hostname	- Target hostname
2211  ipaddr	- see above
2212  netmask	- Subnet Mask
2213  rootpath	- Pathname of the root filesystem on the NFS server
2214  serverip	- see above
2215
2216
2217There are two special Environment Variables:
2218
2219  serial#	- contains hardware identification information such
2220		  as type string and/or serial number
2221  ethaddr	- Ethernet address
2222
2223These variables can be set only once (usually during manufacturing of
2224the board). U-Boot refuses to delete or overwrite these variables
2225once they have been set once.
2226
2227
2228Further special Environment Variables:
2229
2230  ver		- Contains the U-Boot version string as printed
2231		  with the "version" command. This variable is
2232		  readonly (see CONFIG_VERSION_VARIABLE).
2233
2234
2235Please note that changes to some configuration parameters may take
2236only effect after the next boot (yes, that's just like Windoze :-).
2237
2238
2239Command Line Parsing:
2240=====================
2241
2242There are two different command line parsers available with U-Boot:
2243the old "simple" one, and the much more powerful "hush" shell:
2244
2245Old, simple command line parser:
2246--------------------------------
2247
2248- supports environment variables (through setenv / saveenv commands)
2249- several commands on one line, separated by ';'
2250- variable substitution using "... $(name) ..." syntax
2251- special characters ('$', ';') can be escaped by prefixing with '\',
2252  for example:
2253	setenv bootcmd bootm \$(address)
2254- You can also escape text by enclosing in single apostrophes, for example:
2255	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
2256
2257Hush shell:
2258-----------
2259
2260- similar to Bourne shell, with control structures like
2261  if...then...else...fi, for...do...done; while...do...done,
2262  until...do...done, ...
2263- supports environment ("global") variables (through setenv / saveenv
2264  commands) and local shell variables (through standard shell syntax
2265  "name=value"); only environment variables can be used with "run"
2266  command
2267
2268General rules:
2269--------------
2270
2271(1) If a command line (or an environment variable executed by a "run"
2272    command) contains several commands separated by semicolon, and
2273    one of these commands fails, then the remaining commands will be
2274    executed anyway.
2275
2276(2) If you execute several variables with one call to run (i. e.
2277    calling run with a list af variables as arguments), any failing
2278    command will cause "run" to terminate, i. e. the remaining
2279    variables are not executed.
2280
2281Note for Redundant Ethernet Interfaces:
2282=======================================
2283
2284Some boards come with redundant ethernet interfaces; U-Boot supports
2285such configurations and is capable of automatic selection of a
2286"working" interface when needed. MAC assignment works as follows:
2287
2288Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2289MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2290"eth1addr" (=>eth1), "eth2addr", ...
2291
2292If the network interface stores some valid MAC address (for instance
2293in SROM), this is used as default address if there is NO correspon-
2294ding setting in the environment; if the corresponding environment
2295variable is set, this overrides the settings in the card; that means:
2296
2297o If the SROM has a valid MAC address, and there is no address in the
2298  environment, the SROM's address is used.
2299
2300o If there is no valid address in the SROM, and a definition in the
2301  environment exists, then the value from the environment variable is
2302  used.
2303
2304o If both the SROM and the environment contain a MAC address, and
2305  both addresses are the same, this MAC address is used.
2306
2307o If both the SROM and the environment contain a MAC address, and the
2308  addresses differ, the value from the environment is used and a
2309  warning is printed.
2310
2311o If neither SROM nor the environment contain a MAC address, an error
2312  is raised.
2313
2314
2315Image Formats:
2316==============
2317
2318The "boot" commands of this monitor operate on "image" files which
2319can be basicly anything, preceeded by a special header; see the
2320definitions in include/image.h for details; basicly, the header
2321defines the following image properties:
2322
2323* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2324  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2325  LynxOS, pSOS, QNX, RTEMS, ARTOS;
2326  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, ARTOS, LynxOS).
2327* Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2328  IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2329  Currently supported: ARM, Intel x86, MIPS, NIOS, PowerPC).
2330* Compression Type (uncompressed, gzip, bzip2)
2331* Load Address
2332* Entry Point
2333* Image Name
2334* Image Timestamp
2335
2336The header is marked by a special Magic Number, and both the header
2337and the data portions of the image are secured against corruption by
2338CRC32 checksums.
2339
2340
2341Linux Support:
2342==============
2343
2344Although U-Boot should support any OS or standalone application
2345easily, the main focus has always been on Linux during the design of
2346U-Boot.
2347
2348U-Boot includes many features that so far have been part of some
2349special "boot loader" code within the Linux kernel. Also, any
2350"initrd" images to be used are no longer part of one big Linux image;
2351instead, kernel and "initrd" are separate images. This implementation
2352serves several purposes:
2353
2354- the same features can be used for other OS or standalone
2355  applications (for instance: using compressed images to reduce the
2356  Flash memory footprint)
2357
2358- it becomes much easier to port new Linux kernel versions because
2359  lots of low-level, hardware dependent stuff are done by U-Boot
2360
2361- the same Linux kernel image can now be used with different "initrd"
2362  images; of course this also means that different kernel images can
2363  be run with the same "initrd". This makes testing easier (you don't
2364  have to build a new "zImage.initrd" Linux image when you just
2365  change a file in your "initrd"). Also, a field-upgrade of the
2366  software is easier now.
2367
2368
2369Linux HOWTO:
2370============
2371
2372Porting Linux to U-Boot based systems:
2373---------------------------------------
2374
2375U-Boot cannot save you from doing all the necessary modifications to
2376configure the Linux device drivers for use with your target hardware
2377(no, we don't intend to provide a full virtual machine interface to
2378Linux :-).
2379
2380But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
2381
2382Just make sure your machine specific header file (for instance
2383include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2384Information structure as we define in include/u-boot.h, and make
2385sure that your definition of IMAP_ADDR uses the same value as your
2386U-Boot configuration in CFG_IMMR.
2387
2388
2389Configuring the Linux kernel:
2390-----------------------------
2391
2392No specific requirements for U-Boot. Make sure you have some root
2393device (initial ramdisk, NFS) for your target system.
2394
2395
2396Building a Linux Image:
2397-----------------------
2398
2399With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2400not used. If you use recent kernel source, a new build target
2401"uImage" will exist which automatically builds an image usable by
2402U-Boot. Most older kernels also have support for a "pImage" target,
2403which was introduced for our predecessor project PPCBoot and uses a
2404100% compatible format.
2405
2406Example:
2407
2408	make TQM850L_config
2409	make oldconfig
2410	make dep
2411	make uImage
2412
2413The "uImage" build target uses a special tool (in 'tools/mkimage') to
2414encapsulate a compressed Linux kernel image with header  information,
2415CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2416
2417* build a standard "vmlinux" kernel image (in ELF binary format):
2418
2419* convert the kernel into a raw binary image:
2420
2421	${CROSS_COMPILE}-objcopy -O binary \
2422				 -R .note -R .comment \
2423				 -S vmlinux linux.bin
2424
2425* compress the binary image:
2426
2427	gzip -9 linux.bin
2428
2429* package compressed binary image for U-Boot:
2430
2431	mkimage -A ppc -O linux -T kernel -C gzip \
2432		-a 0 -e 0 -n "Linux Kernel Image" \
2433		-d linux.bin.gz uImage
2434
2435
2436The "mkimage" tool can also be used to create ramdisk images for use
2437with U-Boot, either separated from the Linux kernel image, or
2438combined into one file. "mkimage" encapsulates the images with a 64
2439byte header containing information about target architecture,
2440operating system, image type, compression method, entry points, time
2441stamp, CRC32 checksums, etc.
2442
2443"mkimage" can be called in two ways: to verify existing images and
2444print the header information, or to build new images.
2445
2446In the first form (with "-l" option) mkimage lists the information
2447contained in the header of an existing U-Boot image; this includes
2448checksum verification:
2449
2450	tools/mkimage -l image
2451	  -l ==> list image header information
2452
2453The second form (with "-d" option) is used to build a U-Boot image
2454from a "data file" which is used as image payload:
2455
2456	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2457		      -n name -d data_file image
2458	  -A ==> set architecture to 'arch'
2459	  -O ==> set operating system to 'os'
2460	  -T ==> set image type to 'type'
2461	  -C ==> set compression type 'comp'
2462	  -a ==> set load address to 'addr' (hex)
2463	  -e ==> set entry point to 'ep' (hex)
2464	  -n ==> set image name to 'name'
2465	  -d ==> use image data from 'datafile'
2466
2467Right now, all Linux kernels use the same load address	(0x00000000),
2468but the entry point address depends on the kernel version:
2469
2470- 2.2.x kernels have the entry point at 0x0000000C,
2471- 2.3.x and later kernels have the entry point at 0x00000000.
2472
2473So a typical call to build a U-Boot image would read:
2474
2475	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2476	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2477	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
2478	> examples/uImage.TQM850L
2479	Image Name:   2.4.4 kernel for TQM850L
2480	Created:      Wed Jul 19 02:34:59 2000
2481	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
2482	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
2483	Load Address: 0x00000000
2484	Entry Point:  0x00000000
2485
2486To verify the contents of the image (or check for corruption):
2487
2488	-> tools/mkimage -l examples/uImage.TQM850L
2489	Image Name:   2.4.4 kernel for TQM850L
2490	Created:      Wed Jul 19 02:34:59 2000
2491	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
2492	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
2493	Load Address: 0x00000000
2494	Entry Point:  0x00000000
2495
2496NOTE: for embedded systems where boot time is critical you can trade
2497speed for memory and install an UNCOMPRESSED image instead: this
2498needs more space in Flash, but boots much faster since it does not
2499need to be uncompressed:
2500
2501	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
2502	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2503	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2504	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
2505	> examples/uImage.TQM850L-uncompressed
2506	Image Name:   2.4.4 kernel for TQM850L
2507	Created:      Wed Jul 19 02:34:59 2000
2508	Image Type:   PowerPC Linux Kernel Image (uncompressed)
2509	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
2510	Load Address: 0x00000000
2511	Entry Point:  0x00000000
2512
2513
2514Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2515when your kernel is intended to use an initial ramdisk:
2516
2517	-> tools/mkimage -n 'Simple Ramdisk Image' \
2518	> -A ppc -O linux -T ramdisk -C gzip \
2519	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2520	Image Name:   Simple Ramdisk Image
2521	Created:      Wed Jan 12 14:01:50 2000
2522	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
2523	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
2524	Load Address: 0x00000000
2525	Entry Point:  0x00000000
2526
2527
2528Installing a Linux Image:
2529-------------------------
2530
2531To downloading a U-Boot image over the serial (console) interface,
2532you must convert the image to S-Record format:
2533
2534	objcopy -I binary -O srec examples/image examples/image.srec
2535
2536The 'objcopy' does not understand the information in the U-Boot
2537image header, so the resulting S-Record file will be relative to
2538address 0x00000000. To load it to a given address, you need to
2539specify the target address as 'offset' parameter with the 'loads'
2540command.
2541
2542Example: install the image to address 0x40100000 (which on the
2543TQM8xxL is in the first Flash bank):
2544
2545	=> erase 40100000 401FFFFF
2546
2547	.......... done
2548	Erased 8 sectors
2549
2550	=> loads 40100000
2551	## Ready for S-Record download ...
2552	~>examples/image.srec
2553	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2554	...
2555	15989 15990 15991 15992
2556	[file transfer complete]
2557	[connected]
2558	## Start Addr = 0x00000000
2559
2560
2561You can check the success of the download using the 'iminfo' command;
2562this includes a checksum verification so you  can  be  sure  no	 data
2563corruption happened:
2564
2565	=> imi 40100000
2566
2567	## Checking Image at 40100000 ...
2568	   Image Name:	 2.2.13 for initrd on TQM850L
2569	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
2570	   Data Size:	 335725 Bytes = 327 kB = 0 MB
2571	   Load Address: 00000000
2572	   Entry Point:	 0000000c
2573	   Verifying Checksum ... OK
2574
2575
2576Boot Linux:
2577-----------
2578
2579The "bootm" command is used to boot an application that is stored in
2580memory (RAM or Flash). In case of a Linux kernel image, the contents
2581of the "bootargs" environment variable is passed to the kernel as
2582parameters. You can check and modify this variable using the
2583"printenv" and "setenv" commands:
2584
2585
2586	=> printenv bootargs
2587	bootargs=root=/dev/ram
2588
2589	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2590
2591	=> printenv bootargs
2592	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2593
2594	=> bootm 40020000
2595	## Booting Linux kernel at 40020000 ...
2596	   Image Name:	 2.2.13 for NFS on TQM850L
2597	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
2598	   Data Size:	 381681 Bytes = 372 kB = 0 MB
2599	   Load Address: 00000000
2600	   Entry Point:	 0000000c
2601	   Verifying Checksum ... OK
2602	   Uncompressing Kernel Image ... OK
2603	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
2604	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2605	time_init: decrementer frequency = 187500000/60
2606	Calibrating delay loop... 49.77 BogoMIPS
2607	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2608	...
2609
2610If you want to boot a Linux kernel with initial ram disk, you pass
2611the memory addresses of both the kernel and the initrd image (PPBCOOT
2612format!) to the "bootm" command:
2613
2614	=> imi 40100000 40200000
2615
2616	## Checking Image at 40100000 ...
2617	   Image Name:	 2.2.13 for initrd on TQM850L
2618	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
2619	   Data Size:	 335725 Bytes = 327 kB = 0 MB
2620	   Load Address: 00000000
2621	   Entry Point:	 0000000c
2622	   Verifying Checksum ... OK
2623
2624	## Checking Image at 40200000 ...
2625	   Image Name:	 Simple Ramdisk Image
2626	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
2627	   Data Size:	 566530 Bytes = 553 kB = 0 MB
2628	   Load Address: 00000000
2629	   Entry Point:	 00000000
2630	   Verifying Checksum ... OK
2631
2632	=> bootm 40100000 40200000
2633	## Booting Linux kernel at 40100000 ...
2634	   Image Name:	 2.2.13 for initrd on TQM850L
2635	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
2636	   Data Size:	 335725 Bytes = 327 kB = 0 MB
2637	   Load Address: 00000000
2638	   Entry Point:	 0000000c
2639	   Verifying Checksum ... OK
2640	   Uncompressing Kernel Image ... OK
2641	## Loading RAMDisk Image at 40200000 ...
2642	   Image Name:	 Simple Ramdisk Image
2643	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
2644	   Data Size:	 566530 Bytes = 553 kB = 0 MB
2645	   Load Address: 00000000
2646	   Entry Point:	 00000000
2647	   Verifying Checksum ... OK
2648	   Loading Ramdisk ... OK
2649	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
2650	Boot arguments: root=/dev/ram
2651	time_init: decrementer frequency = 187500000/60
2652	Calibrating delay loop... 49.77 BogoMIPS
2653	...
2654	RAMDISK: Compressed image found at block 0
2655	VFS: Mounted root (ext2 filesystem).
2656
2657	bash#
2658
2659More About U-Boot Image Types:
2660------------------------------
2661
2662U-Boot supports the following image types:
2663
2664   "Standalone Programs" are directly runnable in the environment
2665	provided by U-Boot; it is expected that (if they behave
2666	well) you can continue to work in U-Boot after return from
2667	the Standalone Program.
2668   "OS Kernel Images" are usually images of some Embedded OS which
2669	will take over control completely. Usually these programs
2670	will install their own set of exception handlers, device
2671	drivers, set up the MMU, etc. - this means, that you cannot
2672	expect to re-enter U-Boot except by resetting the CPU.
2673   "RAMDisk Images" are more or less just data blocks, and their
2674	parameters (address, size) are passed to an OS kernel that is
2675	being started.
2676   "Multi-File Images" contain several images, typically an OS
2677	(Linux) kernel image and one or more data images like
2678	RAMDisks. This construct is useful for instance when you want
2679	to boot over the network using BOOTP etc., where the boot
2680	server provides just a single image file, but you want to get
2681	for instance an OS kernel and a RAMDisk image.
2682
2683	"Multi-File Images" start with a list of image sizes, each
2684	image size (in bytes) specified by an "uint32_t" in network
2685	byte order. This list is terminated by an "(uint32_t)0".
2686	Immediately after the terminating 0 follow the images, one by
2687	one, all aligned on "uint32_t" boundaries (size rounded up to
2688	a multiple of 4 bytes).
2689
2690   "Firmware Images" are binary images containing firmware (like
2691	U-Boot or FPGA images) which usually will be programmed to
2692	flash memory.
2693
2694   "Script files" are command sequences that will be executed by
2695	U-Boot's command interpreter; this feature is especially
2696	useful when you configure U-Boot to use a real shell (hush)
2697	as command interpreter.
2698
2699
2700Standalone HOWTO:
2701=================
2702
2703One of the features of U-Boot is that you can dynamically load and
2704run "standalone" applications, which can use some resources of
2705U-Boot like console I/O functions or interrupt services.
2706
2707Two simple examples are included with the sources:
2708
2709"Hello World" Demo:
2710-------------------
2711
2712'examples/hello_world.c' contains a small "Hello World" Demo
2713application; it is automatically compiled when you build U-Boot.
2714It's configured to run at address 0x00040004, so you can play with it
2715like that:
2716
2717	=> loads
2718	## Ready for S-Record download ...
2719	~>examples/hello_world.srec
2720	1 2 3 4 5 6 7 8 9 10 11 ...
2721	[file transfer complete]
2722	[connected]
2723	## Start Addr = 0x00040004
2724
2725	=> go 40004 Hello World! This is a test.
2726	## Starting application at 0x00040004 ...
2727	Hello World
2728	argc = 7
2729	argv[0] = "40004"
2730	argv[1] = "Hello"
2731	argv[2] = "World!"
2732	argv[3] = "This"
2733	argv[4] = "is"
2734	argv[5] = "a"
2735	argv[6] = "test."
2736	argv[7] = "<NULL>"
2737	Hit any key to exit ...
2738
2739	## Application terminated, rc = 0x0
2740
2741Another example, which demonstrates how to register a CPM interrupt
2742handler with the U-Boot code, can be found in 'examples/timer.c'.
2743Here, a CPM timer is set up to generate an interrupt every second.
2744The interrupt service routine is trivial, just printing a '.'
2745character, but this is just a demo program. The application can be
2746controlled by the following keys:
2747
2748	? - print current values og the CPM Timer registers
2749	b - enable interrupts and start timer
2750	e - stop timer and disable interrupts
2751	q - quit application
2752
2753	=> loads
2754	## Ready for S-Record download ...
2755	~>examples/timer.srec
2756	1 2 3 4 5 6 7 8 9 10 11 ...
2757	[file transfer complete]
2758	[connected]
2759	## Start Addr = 0x00040004
2760
2761	=> go 40004
2762	## Starting application at 0x00040004 ...
2763	TIMERS=0xfff00980
2764	Using timer 1
2765	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
2766
2767Hit 'b':
2768	[q, b, e, ?] Set interval 1000000 us
2769	Enabling timer
2770Hit '?':
2771	[q, b, e, ?] ........
2772	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
2773Hit '?':
2774	[q, b, e, ?] .
2775	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
2776Hit '?':
2777	[q, b, e, ?] .
2778	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
2779Hit '?':
2780	[q, b, e, ?] .
2781	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
2782Hit 'e':
2783	[q, b, e, ?] ...Stopping timer
2784Hit 'q':
2785	[q, b, e, ?] ## Application terminated, rc = 0x0
2786
2787
2788Minicom warning:
2789================
2790
2791Over time, many people have reported problems when trying to use the
2792"minicom" terminal emulation program for serial download. I (wd)
2793consider minicom to be broken, and recommend not to use it. Under
2794Unix, I recommend to use C-Kermit for general purpose use (and
2795especially for kermit binary protocol download ("loadb" command), and
2796use "cu" for S-Record download ("loads" command).
2797
2798Nevertheless, if you absolutely want to use it try adding this
2799configuration to your "File transfer protocols" section:
2800
2801	   Name    Program                      Name U/D FullScr IO-Red. Multi
2802	X  kermit  /usr/bin/kermit -i -l %l -s   Y    U    Y       N      N
2803	Y  kermit  /usr/bin/kermit -i -l %l -r   N    D    Y       N      N
2804
2805
2806NetBSD Notes:
2807=============
2808
2809Starting at version 0.9.2, U-Boot supports NetBSD both as host
2810(build U-Boot) and target system (boots NetBSD/mpc8xx).
2811
2812Building requires a cross environment; it is known to work on
2813NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
2814need gmake since the Makefiles are not compatible with BSD make).
2815Note that the cross-powerpc package does not install include files;
2816attempting to build U-Boot will fail because <machine/ansi.h> is
2817missing.  This file has to be installed and patched manually:
2818
2819	# cd /usr/pkg/cross/powerpc-netbsd/include
2820	# mkdir powerpc
2821	# ln -s powerpc machine
2822	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
2823	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
2824
2825Native builds *don't* work due to incompatibilities between native
2826and U-Boot include files.
2827
2828Booting assumes that (the first part of) the image booted is a
2829stage-2 loader which in turn loads and then invokes the kernel
2830proper. Loader sources will eventually appear in the NetBSD source
2831tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
2832meantime, send mail to bruno@exet-ag.de and/or wd@denx.de for
2833details.
2834
2835
2836Implementation Internals:
2837=========================
2838
2839The following is not intended to be a complete description of every
2840implementation detail. However, it should help to understand the
2841inner workings of U-Boot and make it easier to port it to custom
2842hardware.
2843
2844
2845Initial Stack, Global Data:
2846---------------------------
2847
2848The implementation of U-Boot is complicated by the fact that U-Boot
2849starts running out of ROM (flash memory), usually without access to
2850system RAM (because the memory controller is not initialized yet).
2851This means that we don't have writable Data or BSS segments, and BSS
2852is not initialized as zero. To be able to get a C environment working
2853at all, we have to allocate at least a minimal stack. Implementation
2854options for this are defined and restricted by the CPU used: Some CPU
2855models provide on-chip memory (like the IMMR area on MPC8xx and
2856MPC826x processors), on others (parts of) the data cache can be
2857locked as (mis-) used as memory, etc.
2858
2859	Chris Hallinan posted a good summary of  these  issues  to  the
2860	u-boot-users mailing list:
2861
2862	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
2863	From: "Chris Hallinan" <clh@net1plus.com>
2864	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
2865	...
2866
2867	Correct me if I'm wrong, folks, but the way I understand it
2868	is this: Using DCACHE as initial RAM for Stack, etc, does not
2869	require any physical RAM backing up the cache. The cleverness
2870	is that the cache is being used as a temporary supply of
2871	necessary storage before the SDRAM controller is setup. It's
2872	beyond the scope of this list to expain the details, but you
2873	can see how this works by studying the cache architecture and
2874	operation in the architecture and processor-specific manuals.
2875
2876	OCM is On Chip Memory, which I believe the 405GP has 4K. It
2877	is another option for the system designer to use as an
2878	initial stack/ram area prior to SDRAM being available. Either
2879	option should work for you. Using CS 4 should be fine if your
2880	board designers haven't used it for something that would
2881	cause you grief during the initial boot! It is frequently not
2882	used.
2883
2884	CFG_INIT_RAM_ADDR should be somewhere that won't interfere
2885	with your processor/board/system design. The default value
2886	you will find in any recent u-boot distribution in
2887	Walnut405.h should work for you. I'd set it to a value larger
2888	than your SDRAM module. If you have a 64MB SDRAM module, set
2889	it above 400_0000. Just make sure your board has no resources
2890	that are supposed to respond to that address! That code in
2891	start.S has been around a while and should work as is when
2892	you get the config right.
2893
2894	-Chris Hallinan
2895	DS4.COM, Inc.
2896
2897It is essential to remember this, since it has some impact on the C
2898code for the initialization procedures:
2899
2900* Initialized global data (data segment) is read-only. Do not attempt
2901  to write it.
2902
2903* Do not use any unitialized global data (or implicitely initialized
2904  as zero data - BSS segment) at all - this is undefined, initiali-
2905  zation is performed later (when relocating to RAM).
2906
2907* Stack space is very limited. Avoid big data buffers or things like
2908  that.
2909
2910Having only the stack as writable memory limits means we cannot use
2911normal global data to share information beween the code. But it
2912turned out that the implementation of U-Boot can be greatly
2913simplified by making a global data structure (gd_t) available to all
2914functions. We could pass a pointer to this data as argument to _all_
2915functions, but this would bloat the code. Instead we use a feature of
2916the GCC compiler (Global Register Variables) to share the data: we
2917place a pointer (gd) to the global data into a register which we
2918reserve for this purpose.
2919
2920When choosing a register for such a purpose we are restricted by the
2921relevant  (E)ABI  specifications for the current architecture, and by
2922GCC's implementation.
2923
2924For PowerPC, the following registers have specific use:
2925	R1:	stack pointer
2926	R2:	TOC pointer
2927	R3-R4:	parameter passing and return values
2928	R5-R10:	parameter passing
2929	R13:	small data area pointer
2930	R30:	GOT pointer
2931	R31:	frame pointer
2932
2933	(U-Boot also uses R14 as internal GOT pointer.)
2934
2935    ==> U-Boot will use R29 to hold a pointer to the global data
2936
2937    Note: on PPC, we could use a static initializer (since the
2938    address of the global data structure is known at compile time),
2939    but it turned out that reserving a register results in somewhat
2940    smaller code - although the code savings are not that big (on
2941    average for all boards 752 bytes for the whole U-Boot image,
2942    624 text + 127 data).
2943
2944On ARM, the following registers are used:
2945
2946	R0:	function argument word/integer result
2947	R1-R3:	function argument word
2948	R9:	GOT pointer
2949	R10:	stack limit (used only if stack checking if enabled)
2950	R11:	argument (frame) pointer
2951	R12:	temporary workspace
2952	R13:	stack pointer
2953	R14:	link register
2954	R15:	program counter
2955
2956    ==> U-Boot will use R8 to hold a pointer to the global data
2957
2958
2959Memory Management:
2960------------------
2961
2962U-Boot runs in system state and uses physical addresses, i.e. the
2963MMU is not used either for address mapping nor for memory protection.
2964
2965The available memory is mapped to fixed addresses using the memory
2966controller. In this process, a contiguous block is formed for each
2967memory type (Flash, SDRAM, SRAM), even when it consists of several
2968physical memory banks.
2969
2970U-Boot is installed in the first 128 kB of the first Flash bank (on
2971TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
2972booting and sizing and initializing DRAM, the code relocates itself
2973to the upper end of DRAM. Immediately below the U-Boot code some
2974memory is reserved for use by malloc() [see CFG_MALLOC_LEN
2975configuration setting]. Below that, a structure with global Board
2976Info data is placed, followed by the stack (growing downward).
2977
2978Additionally, some exception handler code is copied to the low 8 kB
2979of DRAM (0x00000000 ... 0x00001FFF).
2980
2981So a typical memory configuration with 16 MB of DRAM could look like
2982this:
2983
2984	0x0000 0000	Exception Vector code
2985	      :
2986	0x0000 1FFF
2987	0x0000 2000	Free for Application Use
2988	      :
2989	      :
2990
2991	      :
2992	      :
2993	0x00FB FF20	Monitor Stack (Growing downward)
2994	0x00FB FFAC	Board Info Data and permanent copy of global data
2995	0x00FC 0000	Malloc Arena
2996	      :
2997	0x00FD FFFF
2998	0x00FE 0000	RAM Copy of Monitor Code
2999	...		eventually: LCD or video framebuffer
3000	...		eventually: pRAM (Protected RAM - unchanged by reset)
3001	0x00FF FFFF	[End of RAM]
3002
3003
3004System Initialization:
3005----------------------
3006
3007In the reset configuration, U-Boot starts at the reset entry point
3008(on most PowerPC systens at address 0x00000100). Because of the reset
3009configuration for CS0# this is a mirror of the onboard Flash memory.
3010To be able to re-map memory U-Boot then jumps to its link address.
3011To be able to implement the initialization code in C, a (small!)
3012initial stack is set up in the internal Dual Ported RAM (in case CPUs
3013which provide such a feature like MPC8xx or MPC8260), or in a locked
3014part of the data cache. After that, U-Boot initializes the CPU core,
3015the caches and the SIU.
3016
3017Next, all (potentially) available memory banks are mapped using a
3018preliminary mapping. For example, we put them on 512 MB boundaries
3019(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3020on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3021programmed for SDRAM access. Using the temporary configuration, a
3022simple memory test is run that determines the size of the SDRAM
3023banks.
3024
3025When there is more than one SDRAM bank, and the banks are of
3026different size, the largest is mapped first. For equal size, the first
3027bank (CS2#) is mapped first. The first mapping is always for address
30280x00000000, with any additional banks following immediately to create
3029contiguous memory starting from 0.
3030
3031Then, the monitor installs itself at the upper end of the SDRAM area
3032and allocates memory for use by malloc() and for the global Board
3033Info data; also, the exception vector code is copied to the low RAM
3034pages, and the final stack is set up.
3035
3036Only after this relocation will you have a "normal" C environment;
3037until that you are restricted in several ways, mostly because you are
3038running from ROM, and because the code will have to be relocated to a
3039new address in RAM.
3040
3041
3042U-Boot Porting Guide:
3043----------------------
3044
3045[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3046list, October 2002]
3047
3048
3049int main (int argc, char *argv[])
3050{
3051	sighandler_t no_more_time;
3052
3053	signal (SIGALRM, no_more_time);
3054	alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
3055
3056	if (available_money > available_manpower) {
3057		pay consultant to port U-Boot;
3058		return 0;
3059	}
3060
3061	Download latest U-Boot source;
3062
3063	Subscribe to u-boot-users mailing list;
3064
3065	if (clueless) {
3066		email ("Hi, I am new to U-Boot, how do I get started?");
3067	}
3068
3069	while (learning) {
3070		Read the README file in the top level directory;
3071		Read http://www.denx.de/re/DPLG.html
3072		Read the source, Luke;
3073	}
3074
3075	if (available_money > toLocalCurrency ($2500)) {
3076		Buy a BDI2000;
3077	} else {
3078		Add a lot of aggravation and time;
3079	}
3080
3081	Create your own board support subdirectory;
3082
3083	Create your own board config file;
3084
3085	while (!running) {
3086		do {
3087			Add / modify source code;
3088		} until (compiles);
3089		Debug;
3090		if (clueless)
3091			email ("Hi, I am having problems...");
3092	}
3093	Send patch file to Wolfgang;
3094
3095	return 0;
3096}
3097
3098void no_more_time (int sig)
3099{
3100      hire_a_guru();
3101}
3102
3103
3104Coding Standards:
3105-----------------
3106
3107All contributions to U-Boot should conform to the Linux kernel
3108coding style; see the file "Documentation/CodingStyle" in your Linux
3109kernel source directory.
3110
3111Please note that U-Boot is implemented in C (and to some small parts
3112in Assembler); no C++ is used, so please do not use C++ style
3113comments (//) in your code.
3114
3115Submissions which do not conform to the standards may be returned
3116with a request to reformat the changes.
3117
3118
3119Submitting Patches:
3120-------------------
3121
3122Since the number of patches for U-Boot is growing, we need to
3123establish some rules. Submissions which do not conform to these rules
3124may be rejected, even when they contain important and valuable stuff.
3125
3126
3127When you send a patch, please include the following information with
3128it:
3129
3130* For bug fixes: a description of the bug and how your patch fixes
3131  this bug. Please try to include a way of demonstrating that the
3132  patch actually fixes something.
3133
3134* For new features: a description of the feature and your
3135  implementation.
3136
3137* A CHANGELOG entry as plaintext (separate from the patch)
3138
3139* For major contributions, your entry to the CREDITS file
3140
3141* When you add support for a new board, don't forget to add this
3142  board to the MAKEALL script, too.
3143
3144* If your patch adds new configuration options, don't forget to
3145  document these in the README file.
3146
3147* The patch itself. If you are accessing the CVS repository use "cvs
3148  update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
3149  version of diff does not support these options, then get the latest
3150  version of GNU diff.
3151
3152  The current directory when running this command shall be the top
3153  level directory of the U-Boot source tree, or it's parent directory
3154  (i. e. please make sure that your patch includes sufficient
3155  directory information for the affected files).
3156
3157  We accept patches as plain text, MIME attachments or as uuencoded
3158  gzipped text.
3159
3160* If one logical set of modifications affects or creates several
3161  files, all these changes shall be submitted in a SINGLE patch file.
3162
3163* Changesets that contain different, unrelated modifications shall be
3164  submitted as SEPARATE patches, one patch per changeset.
3165
3166
3167Notes:
3168
3169* Before sending the patch, run the MAKEALL script on your patched
3170  source tree and make sure that no errors or warnings are reported
3171  for any of the boards.
3172
3173* Keep your modifications to the necessary minimum: A patch
3174  containing several unrelated changes or arbitrary reformats will be
3175  returned with a request to re-formatting / split it.
3176
3177* If you modify existing code, make sure that your new code does not
3178  add to the memory footprint of the code ;-) Small is beautiful!
3179  When adding new features, these should compile conditionally only
3180  (using #ifdef), and the resulting code with the new feature
3181  disabled must not need more memory than the old code without your
3182  modification.
3183