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 dependend files 123- common Misc architecture independend functions 124- cpu CPU specific files 125- disk Code for disk drive partition handling 126- doc Documentation (don't expect too much) 127- drivers Common 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/mpc8xx Files specific to Motorola MPC8xx CPUs 144- cpu/mpc824x Files specific to Motorola MPC824x CPUs 145- cpu/mpc8260 Files specific to Motorola MPC8260 CPU 146- cpu/ppc4xx Files specific to IBM 4xx CPUs 147 148- board/LEOX/ Files specific to boards manufactured by The LEOX team 149- board/LEOX/elpt860 Files specific to ELPT860 boards 150- board/RPXClassic 151 Files specific to RPXClassic boards 152- board/RPXlite Files specific to RPXlite boards 153- board/c2mon Files specific to c2mon boards 154- board/cogent Files specific to Cogent boards 155 (need further configuration) 156 Files specific to CPCIISER4 boards 157- board/cpu86 Files specific to CPU86 boards 158- board/cray/ Files specific to boards manufactured by Cray 159- board/cray/L1 Files specific to L1 boards 160- board/cu824 Files specific to CU824 boards 161- board/ebony Files specific to IBM Ebony board 162- board/eric Files specific to ERIC boards 163- board/esd/ Files specific to boards manufactured by ESD 164- board/esd/adciop Files specific to ADCIOP boards 165- board/esd/ar405 Files specific to AR405 boards 166- board/esd/canbt Files specific to CANBT boards 167- board/esd/cpci405 Files specific to CPCI405 boards 168- board/esd/cpciiser4 Files specific to CPCIISER4 boards 169- board/esd/common Common files for ESD boards 170- board/esd/dasa_sim Files specific to DASA_SIM boards 171- board/esd/du405 Files specific to DU405 boards 172- board/esd/ocrtc Files specific to OCRTC boards 173- board/esd/pci405 Files specific to PCI405 boards 174- board/esteem192e 175 Files specific to ESTEEM192E boards 176- board/etx094 Files specific to ETX_094 boards 177- board/evb64260 178 Files specific to EVB64260 boards 179- board/fads Files specific to FADS boards 180- board/flagadm Files specific to FLAGADM boards 181- board/gen860t Files specific to GEN860T boards 182- board/genietv Files specific to GENIETV boards 183- board/gth Files specific to GTH boards 184- board/hermes Files specific to HERMES boards 185- board/hymod Files specific to HYMOD boards 186- board/icu862 Files specific to ICU862 boards 187- board/ip860 Files specific to IP860 boards 188- board/iphase4539 189 Files specific to Interphase4539 boards 190- board/ivm Files specific to IVMS8/IVML24 boards 191- board/lantec Files specific to LANTEC boards 192- board/lwmon Files specific to LWMON boards 193- board/mbx8xx Files specific to MBX boards 194- board/mpc8260ads 195 Files specific to MMPC8260ADS boards 196- board/mpl/ Files specific to boards manufactured by MPL 197- board/mpl/common Common files for MPL boards 198- board/mpl/pip405 Files specific to PIP405 boards 199- board/mpl/mip405 Files specific to MIP405 boards 200- board/musenki Files specific to MUSEKNI boards 201- board/mvs1 Files specific to MVS1 boards 202- board/nx823 Files specific to NX823 boards 203- board/oxc Files specific to OXC boards 204- board/pcippc2 Files specific to PCIPPC2/PCIPPC6 boards 205- board/pm826 Files specific to PM826 boards 206- board/ppmc8260 207 Files specific to PPMC8260 boards 208- board/rpxsuper 209 Files specific to RPXsuper boards 210- board/rsdproto 211 Files specific to RSDproto boards 212- board/sandpoint 213 Files specific to Sandpoint boards 214- board/sbc8260 Files specific to SBC8260 boards 215- board/sacsng Files specific to SACSng boards 216- board/siemens Files specific to boards manufactured by Siemens AG 217- board/siemens/CCM Files specific to CCM boards 218- board/siemens/IAD210 Files specific to IAD210 boards 219- board/siemens/SCM Files specific to SCM boards 220- board/siemens/pcu_e Files specific to PCU_E boards 221- board/sixnet Files specific to SIXNET boards 222- board/spd8xx Files specific to SPD8xxTS boards 223- board/tqm8260 Files specific to TQM8260 boards 224- board/tqm8xx Files specific to TQM8xxL boards 225- board/w7o Files specific to W7O boards 226- board/walnut405 227 Files specific to Walnut405 boards 228- board/westel/ Files specific to boards manufactured by Westel Wireless 229- board/westel/amx860 Files specific to AMX860 boards 230- board/utx8245 Files specific to UTX8245 boards 231 232Software Configuration: 233======================= 234 235Configuration is usually done using C preprocessor defines; the 236rationale behind that is to avoid dead code whenever possible. 237 238There are two classes of configuration variables: 239 240* Configuration _OPTIONS_: 241 These are selectable by the user and have names beginning with 242 "CONFIG_". 243 244* Configuration _SETTINGS_: 245 These depend on the hardware etc. and should not be meddled with if 246 you don't know what you're doing; they have names beginning with 247 "CFG_". 248 249Later we will add a configuration tool - probably similar to or even 250identical to what's used for the Linux kernel. Right now, we have to 251do the configuration by hand, which means creating some symbolic 252links and editing some configuration files. We use the TQM8xxL boards 253as an example here. 254 255 256Selection of Processor Architecture and Board Type: 257--------------------------------------------------- 258 259For all supported boards there are ready-to-use default 260configurations available; just type "make <board_name>_config". 261 262Example: For a TQM823L module type: 263 264 cd u-boot 265 make TQM823L_config 266 267For the Cogent platform, you need to specify the cpu type as well; 268e.g. "make cogent_mpc8xx_config". And also configure the cogent 269directory according to the instructions in cogent/README. 270 271 272Configuration Options: 273---------------------- 274 275Configuration depends on the combination of board and CPU type; all 276such information is kept in a configuration file 277"include/configs/<board_name>.h". 278 279Example: For a TQM823L module, all configuration settings are in 280"include/configs/TQM823L.h". 281 282 283Many of the options are named exactly as the corresponding Linux 284kernel configuration options. The intention is to make it easier to 285build a config tool - later. 286 287 288The following options need to be configured: 289 290- CPU Type: Define exactly one of 291 292 PowerPC based CPUs: 293 ------------------- 294 CONFIG_MPC823, CONFIG_MPC850, CONFIG_MPC855, CONFIG_MPC860 295 or CONFIG_MPC824X, CONFIG_MPC8260 296 or CONFIG_IOP480 297 or CONFIG_405GP 298 or CONFIG_440 299 or CONFIG_MPC74xx 300 301 ARM based CPUs: 302 --------------- 303 CONFIG_SA1110 304 CONFIG_ARM7 305 CONFIG_PXA250 306 307 308- Board Type: Define exactly one of 309 310 PowerPC based boards: 311 --------------------- 312 313 CONFIG_ADCIOP, CONFIG_ICU862 CONFIG_RPXsuper, 314 CONFIG_ADS860, CONFIG_IP860, CONFIG_SM850, 315 CONFIG_AMX860, CONFIG_IPHASE4539, CONFIG_SPD823TS, 316 CONFIG_AR405, CONFIG_IVML24, CONFIG_SXNI855T, 317 CONFIG_BAB7xx, CONFIG_IVML24_128, CONFIG_Sandpoint8240, 318 CONFIG_CANBT, CONFIG_IVML24_256, CONFIG_Sandpoint8245, 319 CONFIG_CCM, CONFIG_IVMS8, CONFIG_TQM823L, 320 CONFIG_CPCI405, CONFIG_IVMS8_128, CONFIG_TQM850L, 321 CONFIG_CPCI4052, CONFIG_IVMS8_256, CONFIG_TQM855L, 322 CONFIG_CPCIISER4, CONFIG_LANTEC, CONFIG_TQM860L, 323 CONFIG_CPU86, CONFIG_MBX, CONFIG_TQM8260, 324 CONFIG_CRAYL1, CONFIG_MBX860T, CONFIG_TTTech, 325 CONFIG_CU824, CONFIG_MHPC, CONFIG_UTX8245, 326 CONFIG_DASA_SIM, CONFIG_MIP405, CONFIG_W7OLMC, 327 CONFIG_DU405, CONFIG_MOUSSE, CONFIG_W7OLMG, 328 CONFIG_ELPPC, CONFIG_MPC8260ADS, CONFIG_WALNUT405, 329 CONFIG_ERIC, CONFIG_MUSENKI, CONFIG_ZUMA, 330 CONFIG_ESTEEM192E, CONFIG_MVS1, CONFIG_c2mon, 331 CONFIG_ETX094, CONFIG_NX823, CONFIG_cogent_mpc8260, 332 CONFIG_EVB64260, CONFIG_OCRTC, CONFIG_cogent_mpc8xx, 333 CONFIG_FADS823, CONFIG_ORSG, CONFIG_ep8260, 334 CONFIG_FADS850SAR, CONFIG_OXC, CONFIG_gw8260, 335 CONFIG_FADS860T, CONFIG_PCI405, CONFIG_hermes, 336 CONFIG_FLAGADM, CONFIG_PCIPPC2, CONFIG_hymod, 337 CONFIG_FPS850L, CONFIG_PCIPPC6, CONFIG_lwmon, 338 CONFIG_GEN860T, CONFIG_PIP405, CONFIG_pcu_e, 339 CONFIG_GENIETV, CONFIG_PM826, CONFIG_ppmc8260, 340 CONFIG_GTH, CONFIG_RPXClassic, CONFIG_rsdproto, 341 CONFIG_IAD210, CONFIG_RPXlite, CONFIG_sbc8260, 342 CONFIG_EBONY, CONFIG_sacsng, CONFIG_FPS860L, 343 CONFIG_V37, CONFIG_ELPT860 344 345 ARM based boards: 346 ----------------- 347 348 CONFIG_HHP_CRADLE, CONFIG_DNP1110, CONFIG_EP7312, 349 CONFIG_IMPA7, CONFIG_LART, CONFIG_LUBBOCK, 350 CONFIG_SHANNON, CONFIG_SMDK2400, CONFIG_SMDK2410, 351 CONFIG_TRAB 352 353 354- CPU Module Type: (if CONFIG_COGENT is defined) 355 Define exactly one of 356 CONFIG_CMA286_60_OLD 357--- FIXME --- not tested yet: 358 CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P, 359 CONFIG_CMA287_23, CONFIG_CMA287_50 360 361- Motherboard Type: (if CONFIG_COGENT is defined) 362 Define exactly one of 363 CONFIG_CMA101, CONFIG_CMA102 364 365- Motherboard I/O Modules: (if CONFIG_COGENT is defined) 366 Define one or more of 367 CONFIG_CMA302 368 369- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined) 370 Define one or more of 371 CONFIG_LCD_HEARTBEAT - update a character position on 372 the lcd display every second with 373 a "rotator" |\-/|\-/ 374 375- MPC824X Family Member (if CONFIG_MPC824X is defined) 376 Define exactly one of 377 CONFIG_MPC8240, CONFIG_MPC8245 378 379- 8xx CPU Options: (if using an 8xx cpu) 380 Define one or more of 381 CONFIG_8xx_GCLK_FREQ - if get_gclk_freq() can not work e.g. 382 no 32KHz reference PIT/RTC clock 383 384- Clock Interface: 385 CONFIG_CLOCKS_IN_MHZ 386 387 U-Boot stores all clock information in Hz 388 internally. For binary compatibility with older Linux 389 kernels (which expect the clocks passed in the 390 bd_info data to be in MHz) the environment variable 391 "clocks_in_mhz" can be defined so that U-Boot 392 converts clock data to MHZ before passing it to the 393 Linux kernel. 394 395 When CONFIG_CLOCKS_IN_MHZ is defined, a definition of 396 "clocks_in_mhz=1" is automatically included in the 397 default environment. 398 399- Console Interface: 400 Depending on board, define exactly one serial port 401 (like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2, 402 CONFIG_8xx_CONS_SCC1, ...), or switch off the serial 403 console by defining CONFIG_8xx_CONS_NONE 404 405 Note: if CONFIG_8xx_CONS_NONE is defined, the serial 406 port routines must be defined elsewhere 407 (i.e. serial_init(), serial_getc(), ...) 408 409 CONFIG_CFB_CONSOLE 410 Enables console device for a color framebuffer. Needs following 411 defines (cf. smiLynxEM, i8042, board/eltec/bab7xx) 412 VIDEO_FB_LITTLE_ENDIAN graphic memory organisation 413 (default big endian) 414 VIDEO_HW_RECTFILL graphic chip supports 415 rectangle fill 416 (cf. smiLynxEM) 417 VIDEO_HW_BITBLT graphic chip supports 418 bit-blit (cf. smiLynxEM) 419 VIDEO_VISIBLE_COLS visible pixel columns 420 (cols=pitch) 421 VIDEO_VISIBLE_ROWS visible pixel rows 422 VIDEO_PIXEL_SIZE bytes per pixel 423 VIDEO_DATA_FORMAT graphic data format 424 (0-5, cf. cfb_console.c) 425 VIDEO_FB_ADRS framebuffer address 426 VIDEO_KBD_INIT_FCT keyboard int fct 427 (i.e. i8042_kbd_init()) 428 VIDEO_TSTC_FCT test char fct 429 (i.e. i8042_tstc) 430 VIDEO_GETC_FCT get char fct 431 (i.e. i8042_getc) 432 CONFIG_CONSOLE_CURSOR cursor drawing on/off 433 (requires blink timer 434 cf. i8042.c) 435 CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c) 436 CONFIG_CONSOLE_TIME display time/date info in 437 upper right corner 438 (requires CFG_CMD_DATE) 439 CONFIG_VIDEO_LOGO display Linux logo in 440 upper left corner 441 CONFIG_VIDEO_BMP_LOGO use bmp_logo.h instead of 442 linux_logo.h for logo. 443 Requires CONFIG_VIDEO_LOGO 444 CONFIG_CONSOLE_EXTRA_INFO 445 addional board info beside 446 the logo 447 448 When CONFIG_CFB_CONSOLE is defined, video console is 449 default i/o. Serial console can be forced with 450 environment 'console=serial'. 451 452- Console Baudrate: 453 CONFIG_BAUDRATE - in bps 454 Select one of the baudrates listed in 455 CFG_BAUDRATE_TABLE, see below. 456 457- Interrupt driven serial port input: 458 CONFIG_SERIAL_SOFTWARE_FIFO 459 460 PPC405GP only. 461 Use an interrupt handler for receiving data on the 462 serial port. It also enables using hardware handshake 463 (RTS/CTS) and UART's built-in FIFO. Set the number of 464 bytes the interrupt driven input buffer should have. 465 466 Set to 0 to disable this feature (this is the default). 467 This will also disable hardware handshake. 468 469- Boot Delay: CONFIG_BOOTDELAY - in seconds 470 Delay before automatically booting the default image; 471 set to -1 to disable autoboot. 472 473 See doc/README.autoboot for these options that 474 work with CONFIG_BOOTDELAY. None are required. 475 CONFIG_BOOT_RETRY_TIME 476 CONFIG_BOOT_RETRY_MIN 477 CONFIG_AUTOBOOT_KEYED 478 CONFIG_AUTOBOOT_PROMPT 479 CONFIG_AUTOBOOT_DELAY_STR 480 CONFIG_AUTOBOOT_STOP_STR 481 CONFIG_AUTOBOOT_DELAY_STR2 482 CONFIG_AUTOBOOT_STOP_STR2 483 CONFIG_ZERO_BOOTDELAY_CHECK 484 CONFIG_RESET_TO_RETRY 485 486- Autoboot Command: 487 CONFIG_BOOTCOMMAND 488 Only needed when CONFIG_BOOTDELAY is enabled; 489 define a command string that is automatically executed 490 when no character is read on the console interface 491 within "Boot Delay" after reset. 492 493 CONFIG_BOOTARGS 494 This can be used to pass arguments to the bootm 495 command. The value of CONFIG_BOOTARGS goes into the 496 environment value "bootargs". 497 498 CONFIG_RAMBOOT and CONFIG_NFSBOOT 499 The value of these goes into the environment as 500 "ramboot" and "nfsboot" respectively, and can be used 501 as a convenience, when switching between booting from 502 ram and nfs. 503 504- Pre-Boot Commands: 505 CONFIG_PREBOOT 506 507 When this option is #defined, the existence of the 508 environment variable "preboot" will be checked 509 immediately before starting the CONFIG_BOOTDELAY 510 countdown and/or running the auto-boot command resp. 511 entering interactive mode. 512 513 This feature is especially useful when "preboot" is 514 automatically generated or modified. For an example 515 see the LWMON board specific code: here "preboot" is 516 modified when the user holds down a certain 517 combination of keys on the (special) keyboard when 518 booting the systems 519 520- Serial Download Echo Mode: 521 CONFIG_LOADS_ECHO 522 If defined to 1, all characters received during a 523 serial download (using the "loads" command) are 524 echoed back. This might be needed by some terminal 525 emulations (like "cu"), but may as well just take 526 time on others. This setting #define's the initial 527 value of the "loads_echo" environment variable. 528 529- Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined) 530 CONFIG_KGDB_BAUDRATE 531 Select one of the baudrates listed in 532 CFG_BAUDRATE_TABLE, see below. 533 534- Monitor Functions: 535 CONFIG_COMMANDS 536 Most monitor functions can be selected (or 537 de-selected) by adjusting the definition of 538 CONFIG_COMMANDS; to select individual functions, 539 #define CONFIG_COMMANDS by "OR"ing any of the 540 following values: 541 542 #define enables commands: 543 ------------------------- 544 CFG_CMD_ASKENV * ask for env variable 545 CFG_CMD_BDI bdinfo 546 CFG_CMD_BEDBUG Include BedBug Debugger 547 CFG_CMD_BOOTD bootd 548 CFG_CMD_CACHE icache, dcache 549 CFG_CMD_CONSOLE coninfo 550 CFG_CMD_DATE * support for RTC, date/time... 551 CFG_CMD_DHCP DHCP support 552 CFG_CMD_ECHO * echo arguments 553 CFG_CMD_EEPROM * EEPROM read/write support 554 CFG_CMD_ELF bootelf, bootvx 555 CFG_CMD_ENV saveenv 556 CFG_CMD_FDC * Floppy Disk Support 557 CFG_CMD_FDOS * Dos diskette Support 558 CFG_CMD_FLASH flinfo, erase, protect 559 CFG_CMD_FPGA FPGA device initialization support 560 CFG_CMD_I2C * I2C serial bus support 561 CFG_CMD_IDE * IDE harddisk support 562 CFG_CMD_IMI iminfo 563 CFG_CMD_IMMAP * IMMR dump support 564 CFG_CMD_IRQ * irqinfo 565 CFG_CMD_KGDB * kgdb 566 CFG_CMD_LOADB loadb 567 CFG_CMD_LOADS loads 568 CFG_CMD_MEMORY md, mm, nm, mw, cp, cmp, crc, base, 569 loop, mtest 570 CFG_CMD_MII MII utility commands 571 CFG_CMD_NET bootp, tftpboot, rarpboot 572 CFG_CMD_PCI * pciinfo 573 CFG_CMD_PCMCIA * PCMCIA support 574 CFG_CMD_REGINFO * Register dump 575 CFG_CMD_RUN run command in env variable 576 CFG_CMD_SCSI * SCSI Support 577 CFG_CMD_SETGETDCR Support for DCR Register access (4xx only) 578 CFG_CMD_SPI * SPI serial bus support 579 CFG_CMD_USB * USB support 580 CFG_CMD_BSP * Board SPecific functions 581 ----------------------------------------------- 582 CFG_CMD_ALL all 583 584 CFG_CMD_DFL Default configuration; at the moment 585 this is includes all commands, except 586 the ones marked with "*" in the list 587 above. 588 589 If you don't define CONFIG_COMMANDS it defaults to 590 CFG_CMD_DFL in include/cmd_confdefs.h. A board can 591 override the default settings in the respective 592 include file. 593 594 EXAMPLE: If you want all functions except of network 595 support you can write: 596 597 #define CONFIG_COMMANDS (CFG_CMD_ALL & ~CFG_CMD_NET) 598 599 600 Note: Don't enable the "icache" and "dcache" commands 601 (configuration option CFG_CMD_CACHE) unless you know 602 what you (and your U-Boot users) are doing. Data 603 cache cannot be enabled on systems like the 8xx or 604 8260 (where accesses to the IMMR region must be 605 uncached), and it cannot be disabled on all other 606 systems where we (mis-) use the data cache to hold an 607 initial stack and some data. 608 609 610 XXX - this list needs to get updated! 611 612- Watchdog: 613 CONFIG_WATCHDOG 614 If this variable is defined, it enables watchdog 615 support. There must support in the platform specific 616 code for a watchdog. For the 8xx and 8260 CPUs, the 617 SIU Watchdog feature is enabled in the SYPCR 618 register. 619 620- Real-Time Clock: 621 622 When CFG_CMD_DATE is selected, the type of the RTC 623 has to be selected, too. Define exactly one of the 624 following options: 625 626 CONFIG_RTC_MPC8xx - use internal RTC of MPC8xx 627 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC 628 CONFIG_RTC_MC146818 - use MC146818 RTC 629 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC 630 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC 631 CONFIG_RTC_DS164x - use Dallas DS164x RTC 632 633- Timestamp Support: 634 635 When CONFIG_TIMESTAMP is selected, the timestamp 636 (date and time) of an image is printed by image 637 commands like bootm or iminfo. This option is 638 automatically enabled when you select CFG_CMD_DATE . 639 640- Partition Support: 641 CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION 642 and/or CONFIG_ISO_PARTITION 643 644 If IDE or SCSI support is enabled (CFG_CMD_IDE or 645 CFG_CMD_SCSI) you must configure support for at least 646 one partition type as well. 647 648- IDE Reset method: 649 CONFIG_IDE_RESET_ROUTINE 650 651 Set this to define that instead of a reset Pin, the 652 routine ide_set_reset(int idereset) will be used. 653 654- ATAPI Support: 655 CONFIG_ATAPI 656 657 Set this to enable ATAPI support. 658 659- SCSI Support: 660 At the moment only there is only support for the 661 SYM53C8XX SCSI controller; define 662 CONFIG_SCSI_SYM53C8XX to enable it. 663 664 CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and 665 CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID * 666 CFG_SCSI_MAX_LUN] can be adjusted to define the 667 maximum numbers of LUNs, SCSI ID's and target 668 devices. 669 CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz) 670 671- NETWORK Support (PCI): 672 CONFIG_EEPRO100 673 Support for Intel 82557/82559/82559ER chips. 674 Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom 675 write routine for first time initialisation. 676 677 CONFIG_TULIP 678 Support for Digital 2114x chips. 679 Optional CONFIG_TULIP_SELECT_MEDIA for board specific 680 modem chip initialisation (KS8761/QS6611). 681 682 CONFIG_NATSEMI 683 Support for National dp83815 chips. 684 685 CONFIG_NS8382X 686 Support for National dp8382[01] gigabit chips. 687 688- USB Support: 689 At the moment only the UHCI host controller is 690 supported (PIP405, MIP405); define 691 CONFIG_USB_UHCI to enable it. 692 define CONFIG_USB_KEYBOARD to enable the USB Keyboard 693 end define CONFIG_USB_STORAGE to enable the USB 694 storage devices. 695 Note: 696 Supported are USB Keyboards and USB Floppy drives 697 (TEAC FD-05PUB). 698 699- Keyboard Support: 700 CONFIG_ISA_KEYBOARD 701 702 Define this to enable standard (PC-Style) keyboard 703 support 704 705 CONFIG_I8042_KBD 706 Standard PC keyboard driver with US (is default) and 707 GERMAN key layout (switch via environment 'keymap=de') support. 708 Export function i8042_kbd_init, i8042_tstc and i8042_getc 709 for cfb_console. Supports cursor blinking. 710 711- Video support: 712 CONFIG_VIDEO 713 714 Define this to enable video support (for output to 715 video). 716 717 CONFIG_VIDEO_CT69000 718 719 Enable Chips & Technologies 69000 Video chip 720 721 CONFIG_VIDEO_SMI_LYNXEM 722 Enable Silicon Motion SMI 712/710/810 Video chip 723 Videomode are selected via environment 'videomode' with 724 standard LiLo mode numbers. 725 Following modes are supported (* is default): 726 727 800x600 1024x768 1280x1024 728 256 (8bit) 303* 305 307 729 65536 (16bit) 314 317 31a 730 16,7 Mill (24bit) 315 318 31b 731 (i.e. setenv videomode 317; saveenv; reset;) 732 733 CONFIG_VIDEO_SED13806 734 Enable Epson SED13806 driver. This driver supports 8bpp 735 and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP 736 or CONFIG_VIDEO_SED13806_16BPP 737 738 739- LCD Support: CONFIG_LCD 740 741 Define this to enable LCD support (for output to LCD 742 display); also select one of the supported displays 743 by defining one of these: 744 745 CONFIG_NEC_NL6648AC33: 746 747 NEC NL6648AC33-18. Active, color, single scan. 748 749 CONFIG_NEC_NL6648BC20 750 751 NEC NL6648BC20-08. 6.5", 640x480. 752 Active, color, single scan. 753 754 CONFIG_SHARP_16x9 755 756 Sharp 320x240. Active, color, single scan. 757 It isn't 16x9, and I am not sure what it is. 758 759 CONFIG_SHARP_LQ64D341 760 761 Sharp LQ64D341 display, 640x480. 762 Active, color, single scan. 763 764 CONFIG_HLD1045 765 766 HLD1045 display, 640x480. 767 Active, color, single scan. 768 769 CONFIG_OPTREX_BW 770 771 Optrex CBL50840-2 NF-FW 99 22 M5 772 or 773 Hitachi LMG6912RPFC-00T 774 or 775 Hitachi SP14Q002 776 777 320x240. Black & white. 778 779 Normally display is black on white background; define 780 CFG_WHITE_ON_BLACK to get it inverted. 781 782- Ethernet address: 783 CONFIG_ETHADDR 784 CONFIG_ETH2ADDR 785 CONFIG_ETH3ADDR 786 787 Define a default value for ethernet address to use 788 for the respective ethernet interface, in case this 789 is not determined automatically. 790 791- IP address: 792 CONFIG_IPADDR 793 794 Define a default value for the IP address to use for 795 the default ethernet interface, in case this is not 796 determined through e.g. bootp. 797 798- Server IP address: 799 CONFIG_SERVERIP 800 801 Defines a default value for theIP address of a TFTP 802 server to contact when using the "tftboot" command. 803 804- BOOTP Recovery Mode: 805 CONFIG_BOOTP_RANDOM_DELAY 806 807 If you have many targets in a network that try to 808 boot using BOOTP, you may want to avoid that all 809 systems send out BOOTP requests at precisely the same 810 moment (which would happen for instance at recovery 811 from a power failure, when all systems will try to 812 boot, thus flooding the BOOTP server. Defining 813 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be 814 inserted before sending out BOOTP requests. The 815 following delays are insterted then: 816 817 1st BOOTP request: delay 0 ... 1 sec 818 2nd BOOTP request: delay 0 ... 2 sec 819 3rd BOOTP request: delay 0 ... 4 sec 820 4th and following 821 BOOTP requests: delay 0 ... 8 sec 822 823- Status LED: CONFIG_STATUS_LED 824 825 Several configurations allow to display the current 826 status using a LED. For instance, the LED will blink 827 fast while running U-Boot code, stop blinking as 828 soon as a reply to a BOOTP request was received, and 829 start blinking slow once the Linux kernel is running 830 (supported by a status LED driver in the Linux 831 kernel). Defining CONFIG_STATUS_LED enables this 832 feature in U-Boot. 833 834- CAN Support: CONFIG_CAN_DRIVER 835 836 Defining CONFIG_CAN_DRIVER enables CAN driver support 837 on those systems that support this (optional) 838 feature, like the TQM8xxL modules. 839 840- I2C Support: CONFIG_HARD_I2C | CONFIG_SOFT_I2C 841 842 Enables I2C serial bus commands. If this is selected, 843 either CONFIG_HARD_I2C or CONFIG_SOFT_I2C must be defined 844 to include the appropriate I2C driver. 845 846 See also: common/cmd_i2c.c for a description of the 847 command line interface. 848 849 850 CONFIG_HARD_I2C 851 852 Selects the CPM hardware driver for I2C. 853 854 CONFIG_SOFT_I2C 855 856 Use software (aka bit-banging) driver instead of CPM 857 or similar hardware support for I2C. This is configured 858 via the following defines. 859 860 I2C_INIT 861 862 (Optional). Any commands necessary to enable I2C 863 controller or configure ports. 864 865 I2C_PORT 866 867 (Only for MPC8260 CPU). The I/O port to use (the code 868 assumes both bits are on the same port). Valid values 869 are 0..3 for ports A..D. 870 871 I2C_ACTIVE 872 873 The code necessary to make the I2C data line active 874 (driven). If the data line is open collector, this 875 define can be null. 876 877 I2C_TRISTATE 878 879 The code necessary to make the I2C data line tri-stated 880 (inactive). If the data line is open collector, this 881 define can be null. 882 883 I2C_READ 884 885 Code that returns TRUE if the I2C data line is high, 886 FALSE if it is low. 887 888 I2C_SDA(bit) 889 890 If <bit> is TRUE, sets the I2C data line high. If it 891 is FALSE, it clears it (low). 892 893 I2C_SCL(bit) 894 895 If <bit> is TRUE, sets the I2C clock line high. If it 896 is FALSE, it clears it (low). 897 898 I2C_DELAY 899 900 This delay is invoked four times per clock cycle so this 901 controls the rate of data transfer. The data rate thus 902 is 1 / (I2C_DELAY * 4). 903 904 CFG_I2C_INIT_BOARD 905 906 When a board is reset during an i2c bus transfer 907 chips might think that the current transfer is still 908 in progress. On some boards it is possible to access 909 the i2c SCLK line directly, either by using the 910 processor pin as a GPIO or by having a second pin 911 connected to the bus. If this option is defined a 912 custom i2c_init_board() routine in boards/xxx/board.c 913 is run early in the boot sequence. 914 915- SPI Support: CONFIG_SPI 916 917 Enables SPI driver (so far only tested with 918 SPI EEPROM, also an instance works with Crystal A/D and 919 D/As on the SACSng board) 920 921 CONFIG_SPI_X 922 923 Enables extended (16-bit) SPI EEPROM addressing. 924 (symmetrical to CONFIG_I2C_X) 925 926 CONFIG_SOFT_SPI 927 928 Enables a software (bit-bang) SPI driver rather than 929 using hardware support. This is a general purpose 930 driver that only requires three general I/O port pins 931 (two outputs, one input) to function. If this is 932 defined, the board configuration must define several 933 SPI configuration items (port pins to use, etc). For 934 an example, see include/configs/sacsng.h. 935 936- FPGA Support: CONFIG_FPGA_COUNT 937 938 Specify the number of FPGA devices to support. 939 940 CONFIG_FPGA 941 942 Used to specify the types of FPGA devices. For 943 example, 944 #define CONFIG_FPGA CFG_XILINX_VIRTEX2 945 946 CFG_FPGA_PROG_FEEDBACK 947 948 Enable printing of hash marks during FPGA 949 configuration. 950 951 CFG_FPGA_CHECK_BUSY 952 953 Enable checks on FPGA configuration interface busy 954 status by the configuration function. This option 955 will require a board or device specific function to 956 be written. 957 958 CONFIG_FPGA_DELAY 959 960 If defined, a function that provides delays in the 961 FPGA configuration driver. 962 963 CFG_FPGA_CHECK_CTRLC 964 965 Allow Control-C to interrupt FPGA configuration 966 967 CFG_FPGA_CHECK_ERROR 968 969 Check for configuration errors during FPGA bitfile 970 loading. For example, abort during Virtex II 971 configuration if the INIT_B line goes low (which 972 indicated a CRC error). 973 974 CFG_FPGA_WAIT_INIT 975 976 Maximum time to wait for the INIT_B line to deassert 977 after PROB_B has been deasserted during a Virtex II 978 FPGA configuration sequence. The default time is 500 mS. 979 980 CFG_FPGA_WAIT_BUSY 981 982 Maximum time to wait for BUSY to deassert during 983 Virtex II FPGA configuration. The default is 5 mS. 984 985 CFG_FPGA_WAIT_CONFIG 986 987 Time to wait after FPGA configuration. The default is 988 200 mS. 989 990- FPGA Support: CONFIG_FPGA_COUNT 991 992 Specify the number of FPGA devices to support. 993 994 CONFIG_FPGA 995 996 Used to specify the types of FPGA devices. For example, 997 #define CONFIG_FPGA CFG_XILINX_VIRTEX2 998 999 CFG_FPGA_PROG_FEEDBACK 1000 1001 Enable printing of hash marks during FPGA configuration. 1002 1003 CFG_FPGA_CHECK_BUSY 1004 1005 Enable checks on FPGA configuration interface busy 1006 status by the configuration function. This option 1007 will require a board or device specific function to 1008 be written. 1009 1010 CONFIG_FPGA_DELAY 1011 1012 If defined, a function that provides delays in the FPGA 1013 configuration driver. 1014 1015 CFG_FPGA_CHECK_CTRLC 1016 Allow Control-C to interrupt FPGA configuration 1017 1018 CFG_FPGA_CHECK_ERROR 1019 1020 Check for configuration errors during FPGA bitfile 1021 loading. For example, abort during Virtex II 1022 configuration if the INIT_B line goes low (which 1023 indicated a CRC error). 1024 1025 CFG_FPGA_WAIT_INIT 1026 1027 Maximum time to wait for the INIT_B line to deassert 1028 after PROB_B has been deasserted during a Virtex II 1029 FPGA configuration sequence. The default time is 500 1030 mS. 1031 1032 CFG_FPGA_WAIT_BUSY 1033 1034 Maximum time to wait for BUSY to deassert during 1035 Virtex II FPGA configuration. The default is 5 mS. 1036 1037 CFG_FPGA_WAIT_CONFIG 1038 1039 Time to wait after FPGA configuration. The default is 1040 200 mS. 1041 1042- Configuration Management: 1043 CONFIG_IDENT_STRING 1044 1045 If defined, this string will be added to the U-Boot 1046 version information (U_BOOT_VERSION) 1047 1048- Vendor Parameter Protection: 1049 1050 U-Boot considers the values of the environment 1051 variables "serial#" (Board Serial Number) and 1052 "ethaddr" (Ethernet Address) to bb parameters that 1053 are set once by the board vendor / manufacturer, and 1054 protects these variables from casual modification by 1055 the user. Once set, these variables are read-only, 1056 and write or delete attempts are rejected. You can 1057 change this behviour: 1058 1059 If CONFIG_ENV_OVERWRITE is #defined in your config 1060 file, the write protection for vendor parameters is 1061 completely disabled. Anybody can change or delete 1062 these parameters. 1063 1064 Alternatively, if you #define _both_ CONFIG_ETHADDR 1065 _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default 1066 ethernet address is installed in the environment, 1067 which can be changed exactly ONCE by the user. [The 1068 serial# is unaffected by this, i. e. it remains 1069 read-only.] 1070 1071- Protected RAM: 1072 CONFIG_PRAM 1073 1074 Define this variable to enable the reservation of 1075 "protected RAM", i. e. RAM which is not overwritten 1076 by U-Boot. Define CONFIG_PRAM to hold the number of 1077 kB you want to reserve for pRAM. You can overwrite 1078 this default value by defining an environment 1079 variable "pram" to the number of kB you want to 1080 reserve. Note that the board info structure will 1081 still show the full amount of RAM. If pRAM is 1082 reserved, a new environment variable "mem" will 1083 automatically be defined to hold the amount of 1084 remaining RAM in a form that can be passed as boot 1085 argument to Linux, for instance like that: 1086 1087 setenv bootargs ... mem=\$(mem) 1088 saveenv 1089 1090 This way you can tell Linux not to use this memory, 1091 either, which results in a memory region that will 1092 not be affected by reboots. 1093 1094 *WARNING* If your board configuration uses automatic 1095 detection of the RAM size, you must make sure that 1096 this memory test is non-destructive. So far, the 1097 following board configurations are known to be 1098 "pRAM-clean": 1099 1100 ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL, 1101 HERMES, IP860, RPXlite, LWMON, LANTEC, 1102 PCU_E, FLAGADM, TQM8260 1103 1104- Error Recovery: 1105 CONFIG_PANIC_HANG 1106 1107 Define this variable to stop the system in case of a 1108 fatal error, so that you have to reset it manually. 1109 This is probably NOT a good idea for an embedded 1110 system where you want to system to reboot 1111 automatically as fast as possible, but it may be 1112 useful during development since you can try to debug 1113 the conditions that lead to the situation. 1114 1115 CONFIG_NET_RETRY_COUNT 1116 1117 This variable defines the number of retries for 1118 network operations like ARP, RARP, TFTP, or BOOTP 1119 before giving up the operation. If not defined, a 1120 default value of 5 is used. 1121 1122- Command Interpreter: 1123 CFG_HUSH_PARSER 1124 1125 Define this variable to enable the "hush" shell (from 1126 Busybox) as command line interpreter, thus enabling 1127 powerful command line syntax like 1128 if...then...else...fi conditionals or `&&' and '||' 1129 constructs ("shell scripts"). 1130 1131 If undefined, you get the old, much simpler behaviour 1132 with a somewhat smaller memory footprint. 1133 1134 1135 CFG_PROMPT_HUSH_PS2 1136 1137 This defines the secondary prompt string, which is 1138 printed when the command interpreter needs more input 1139 to complete a command. Usually "> ". 1140 1141 Note: 1142 1143 In the current implementation, the local variables 1144 space and global environment variables space are 1145 separated. Local variables are those you define by 1146 simply typing like `name=value'. To access a local 1147 variable later on, you have write `$name' or 1148 `${name}'; variable directly by typing say `$name' at 1149 the command prompt. 1150 1151 Global environment variables are those you use 1152 setenv/printenv to work with. To run a command stored 1153 in such a variable, you need to use the run command, 1154 and you must not use the '$' sign to access them. 1155 1156 To store commands and special characters in a 1157 variable, please use double quotation marks 1158 surrounding the whole text of the variable, instead 1159 of the backslashes before semicolons and special 1160 symbols. 1161 1162- Default Environment 1163 CONFIG_EXTRA_ENV_SETTINGS 1164 1165 Define this to contain any number of null terminated 1166 strings (variable = value pairs) that will be part of 1167 the default enviroment compiled into the boot image. 1168 1169 For example, place something like this in your 1170 board's config file: 1171 1172 #define CONFIG_EXTRA_ENV_SETTINGS \ 1173 "myvar1=value1\0" \ 1174 "myvar2=value2\0" 1175 1176 Warning: This method is based on knowledge about the 1177 internal format how the environment is stored by the 1178 U-Boot code. This is NOT an official, exported 1179 interface! Although it is unlikely that this format 1180 will change soon, but there is no guarantee either. 1181 You better know what you are doing here. 1182 1183 Note: overly (ab)use of the default environment is 1184 discouraged. Make sure to check other ways to preset 1185 the environment like the autoscript function or the 1186 boot command first. 1187 1188- Show boot progress 1189 CONFIG_SHOW_BOOT_PROGRESS 1190 1191 Defining this option allows to add some board- 1192 specific code (calling a user-provided function 1193 "show_boot_progress(int)") that enables you to show 1194 the system's boot progress on some display (for 1195 example, some LED's) on your board. At the moment, 1196 the following checkpoints are implemented: 1197 1198 Arg Where When 1199 1 common/cmd_bootm.c before attempting to boot an image 1200 -1 common/cmd_bootm.c Image header has bad magic number 1201 2 common/cmd_bootm.c Image header has correct magic number 1202 -2 common/cmd_bootm.c Image header has bad checksum 1203 3 common/cmd_bootm.c Image header has correct checksum 1204 -3 common/cmd_bootm.c Image data has bad checksum 1205 4 common/cmd_bootm.c Image data has correct checksum 1206 -4 common/cmd_bootm.c Image is for unsupported architecture 1207 5 common/cmd_bootm.c Architecture check OK 1208 -5 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone) 1209 6 common/cmd_bootm.c Image Type check OK 1210 -6 common/cmd_bootm.c gunzip uncompression error 1211 -7 common/cmd_bootm.c Unimplemented compression type 1212 7 common/cmd_bootm.c Uncompression OK 1213 -8 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone) 1214 8 common/cmd_bootm.c Image Type check OK 1215 -9 common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX) 1216 9 common/cmd_bootm.c Start initial ramdisk verification 1217 -10 common/cmd_bootm.c Ramdisk header has bad magic number 1218 -11 common/cmd_bootm.c Ramdisk header has bad checksum 1219 10 common/cmd_bootm.c Ramdisk header is OK 1220 -12 common/cmd_bootm.c Ramdisk data has bad checksum 1221 11 common/cmd_bootm.c Ramdisk data has correct checksum 1222 12 common/cmd_bootm.c Ramdisk verification complete, start loading 1223 -13 common/cmd_bootm.c Wrong Image Type (not PPC Linux Ramdisk) 1224 13 common/cmd_bootm.c Start multifile image verification 1225 14 common/cmd_bootm.c No initial ramdisk, no multifile, continue. 1226 15 common/cmd_bootm.c All preparation done, transferring control to OS 1227 1228 -1 common/cmd_doc.c Bad usage of "doc" command 1229 -1 common/cmd_doc.c No boot device 1230 -1 common/cmd_doc.c Unknown Chip ID on boot device 1231 -1 common/cmd_doc.c Read Error on boot device 1232 -1 common/cmd_doc.c Image header has bad magic number 1233 1234 -1 common/cmd_ide.c Bad usage of "ide" command 1235 -1 common/cmd_ide.c No boot device 1236 -1 common/cmd_ide.c Unknown boot device 1237 -1 common/cmd_ide.c Unknown partition table 1238 -1 common/cmd_ide.c Invalid partition type 1239 -1 common/cmd_ide.c Read Error on boot device 1240 -1 common/cmd_ide.c Image header has bad magic number 1241 1242 -1 common/cmd_nvedit.c Environment not changable, but has bad CRC 1243 1244 1245Modem Support: 1246-------------- 1247 1248[so far only for SMDK2400 board] 1249 1250- Modem support endable: 1251 CONFIG_MODEM_SUPPORT 1252 1253- RTS/CTS Flow control enable: 1254 CONFIG_HWFLOW 1255 1256- Modem debug support: 1257 CONFIG_MODEM_SUPPORT_DEBUG 1258 1259 Enables debugging stuff (char screen[1024], dbg()) 1260 for modem support. Useful only with BDI2000. 1261 1262- General: 1263 1264 In the target system modem support is enabled when a 1265 specific key (key combination) is pressed during 1266 power-on. Otherwise U-Boot will boot normally 1267 (autoboot). The key_pressed() fuction is called from 1268 board_init(). Currently key_pressed() is a dummy 1269 function, returning 1 and thus enabling modem 1270 initialization. 1271 1272 If there are no modem init strings in the 1273 environment, U-Boot proceed to autoboot; the 1274 previous output (banner, info printfs) will be 1275 supressed, though. 1276 1277 See also: doc/README.Modem 1278 1279 1280 1281 1282Configuration Settings: 1283----------------------- 1284 1285- CFG_LONGHELP: Defined when you want long help messages included; 1286 undefine this when you're short of memory. 1287 1288- CFG_PROMPT: This is what U-Boot prints on the console to 1289 prompt for user input. 1290 1291- CFG_CBSIZE: Buffer size for input from the Console 1292 1293- CFG_PBSIZE: Buffer size for Console output 1294 1295- CFG_MAXARGS: max. Number of arguments accepted for monitor commands 1296 1297- CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to 1298 the application (usually a Linux kernel) when it is 1299 booted 1300 1301- CFG_BAUDRATE_TABLE: 1302 List of legal baudrate settings for this board. 1303 1304- CFG_CONSOLE_INFO_QUIET 1305 Suppress display of console information at boot. 1306 1307- CFG_CONSOLE_IS_IN_ENV 1308 If the board specific function 1309 extern int overwrite_console (void); 1310 returns 1, the stdin, stderr and stdout are switched to the 1311 serial port, else the settings in the environment are used. 1312 1313- CFG_CONSOLE_OVERWRITE_ROUTINE 1314 Enable the call to overwrite_console(). 1315 1316- CFG_CONSOLE_ENV_OVERWRITE 1317 Enable overwrite of previous console environment settings. 1318 1319- CFG_MEMTEST_START, CFG_MEMTEST_END: 1320 Begin and End addresses of the area used by the 1321 simple memory test. 1322 1323- CFG_ALT_MEMTEST: 1324 Enable an alternate, more extensive memory test. 1325 1326- CFG_TFTP_LOADADDR: 1327 Default load address for network file downloads 1328 1329- CFG_LOADS_BAUD_CHANGE: 1330 Enable temporary baudrate change while serial download 1331 1332- CFG_SDRAM_BASE: 1333 Physical start address of SDRAM. _Must_ be 0 here. 1334 1335- CFG_MBIO_BASE: 1336 Physical start address of Motherboard I/O (if using a 1337 Cogent motherboard) 1338 1339- CFG_FLASH_BASE: 1340 Physical start address of Flash memory. 1341 1342- CFG_MONITOR_BASE: 1343 Physical start address of boot monitor code (set by 1344 make config files to be same as the text base address 1345 (TEXT_BASE) used when linking) - same as 1346 CFG_FLASH_BASE when booting from flash. 1347 1348- CFG_MONITOR_LEN: 1349 Size of memory reserved for monitor code 1350 1351- CFG_MALLOC_LEN: 1352 Size of DRAM reserved for malloc() use. 1353 1354- CFG_BOOTMAPSZ: 1355 Maximum size of memory mapped by the startup code of 1356 the Linux kernel; all data that must be processed by 1357 the Linux kernel (bd_info, boot arguments, eventually 1358 initrd image) must be put below this limit. 1359 1360- CFG_MAX_FLASH_BANKS: 1361 Max number of Flash memory banks 1362 1363- CFG_MAX_FLASH_SECT: 1364 Max number of sectors on a Flash chip 1365 1366- CFG_FLASH_ERASE_TOUT: 1367 Timeout for Flash erase operations (in ms) 1368 1369- CFG_FLASH_WRITE_TOUT: 1370 Timeout for Flash write operations (in ms) 1371 1372- CFG_DIRECT_FLASH_TFTP: 1373 1374 Enable TFTP transfers directly to flash memory; 1375 without this option such a download has to be 1376 performed in two steps: (1) download to RAM, and (2) 1377 copy from RAM to flash. 1378 1379 The two-step approach is usually more reliable, since 1380 you can check if the download worked before you erase 1381 the flash, but in some situations (when sytem RAM is 1382 too limited to allow for a tempory copy of the 1383 downloaded image) this option may be very useful. 1384 1385- CFG_FLASH_CFI: 1386 Define if the flash driver uses extra elements in the 1387 common flash structure for storing flash geometry 1388 1389The following definitions that deal with the placement and management 1390of environment data (variable area); in general, we support the 1391following configurations: 1392 1393- CFG_ENV_IS_IN_FLASH: 1394 1395 Define this if the environment is in flash memory. 1396 1397 a) The environment occupies one whole flash sector, which is 1398 "embedded" in the text segment with the U-Boot code. This 1399 happens usually with "bottom boot sector" or "top boot 1400 sector" type flash chips, which have several smaller 1401 sectors at the start or the end. For instance, such a 1402 layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In 1403 such a case you would place the environment in one of the 1404 4 kB sectors - with U-Boot code before and after it. With 1405 "top boot sector" type flash chips, you would put the 1406 environment in one of the last sectors, leaving a gap 1407 between U-Boot and the environment. 1408 1409 - CFG_ENV_OFFSET: 1410 1411 Offset of environment data (variable area) to the 1412 beginning of flash memory; for instance, with bottom boot 1413 type flash chips the second sector can be used: the offset 1414 for this sector is given here. 1415 1416 CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE. 1417 1418 - CFG_ENV_ADDR: 1419 1420 This is just another way to specify the start address of 1421 the flash sector containing the environment (instead of 1422 CFG_ENV_OFFSET). 1423 1424 - CFG_ENV_SECT_SIZE: 1425 1426 Size of the sector containing the environment. 1427 1428 1429 b) Sometimes flash chips have few, equal sized, BIG sectors. 1430 In such a case you don't want to spend a whole sector for 1431 the environment. 1432 1433 - CFG_ENV_SIZE: 1434 1435 If you use this in combination with CFG_ENV_IS_IN_FLASH 1436 and CFG_ENV_SECT_SIZE, you can specify to use only a part 1437 of this flash sector for the environment. This saves 1438 memory for the RAM copy of the environment. 1439 1440 It may also save flash memory if you decide to use this 1441 when your environment is "embedded" within U-Boot code, 1442 since then the remainder of the flash sector could be used 1443 for U-Boot code. It should be pointed out that this is 1444 STRONGLY DISCOURAGED from a robustness point of view: 1445 updating the environment in flash makes it always 1446 necessary to erase the WHOLE sector. If something goes 1447 wrong before the contents has been restored from a copy in 1448 RAM, your target system will be dead. 1449 1450 - CFG_ENV_ADDR_REDUND 1451 CFG_ENV_SIZE_REDUND 1452 1453 These settings describe a second storage area used to hold 1454 a redundand copy of the environment data, so that there is 1455 a valid backup copy in case there is a power failur during 1456 a "saveenv" operation. 1457 1458BE CAREFUL! Any changes to the flash layout, and some changes to the 1459source code will make it necessary to adapt <board>/u-boot.lds* 1460accordingly! 1461 1462 1463- CFG_ENV_IS_IN_NVRAM: 1464 1465 Define this if you have some non-volatile memory device 1466 (NVRAM, battery buffered SRAM) which you want to use for the 1467 environment. 1468 1469 - CFG_ENV_ADDR: 1470 - CFG_ENV_SIZE: 1471 1472 These two #defines are used to determin the memory area you 1473 want to use for environment. It is assumed that this memory 1474 can just be read and written to, without any special 1475 provision. 1476 1477BE CAREFUL! The first access to the environment happens quite early 1478in U-Boot initalization (when we try to get the setting of for the 1479console baudrate). You *MUST* have mappend your NVRAM area then, or 1480U-Boot will hang. 1481 1482Please note that even with NVRAM we still use a copy of the 1483environment in RAM: we could work on NVRAM directly, but we want to 1484keep settings there always unmodified except somebody uses "saveenv" 1485to save the current settings. 1486 1487 1488- CFG_ENV_IS_IN_EEPROM: 1489 1490 Use this if you have an EEPROM or similar serial access 1491 device and a driver for it. 1492 1493 - CFG_ENV_OFFSET: 1494 - CFG_ENV_SIZE: 1495 1496 These two #defines specify the offset and size of the 1497 environment area within the total memory of your EEPROM. 1498 1499 - CFG_I2C_EEPROM_ADDR: 1500 If defined, specified the chip address of the EEPROM device. 1501 The default address is zero. 1502 1503 - CFG_EEPROM_PAGE_WRITE_BITS: 1504 If defined, the number of bits used to address bytes in a 1505 single page in the EEPROM device. A 64 byte page, for example 1506 would require six bits. 1507 1508 - CFG_EEPROM_PAGE_WRITE_DELAY_MS: 1509 If defined, the number of milliseconds to delay between 1510 page writes. The default is zero milliseconds. 1511 1512 - CFG_I2C_EEPROM_ADDR_LEN: 1513 The length in bytes of the EEPROM memory array address. Note 1514 that this is NOT the chip address length! 1515 1516 - CFG_EEPROM_SIZE: 1517 The size in bytes of the EEPROM device. 1518 1519 1520- CFG_SPI_INIT_OFFSET 1521 1522 Defines offset to the initial SPI buffer area in DPRAM. The 1523 area is used at an early stage (ROM part) if the environment 1524 is configured to reside in the SPI EEPROM: We need a 520 byte 1525 scratch DPRAM area. It is used between the two initialization 1526 calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems 1527 to be a good choice since it makes it far enough from the 1528 start of the data area as well as from the stack pointer. 1529 1530Please note that the environment is read-only as long as the monitor 1531has been relocated to RAM and a RAM copy of the environment has been 1532created; also, when using EEPROM you will have to use getenv_r() 1533until then to read environment variables. 1534 1535The environment is now protected by a CRC32 checksum. Before the 1536monitor is relocated into RAM, as a result of a bad CRC you will be 1537working with the compiled-in default environment - *silently*!!! 1538[This is necessary, because the first environment variable we need is 1539the "baudrate" setting for the console - if we have a bad CRC, we 1540don't have any device yet where we could complain.] 1541 1542Note: once the monitor has been relocated, then it will complain if 1543the default environment is used; a new CRC is computed as soon as you 1544use the "setenv" command to modify / delete / add any environment 1545variable [even when you try to delete a non-existing variable!]. 1546 1547Note2: you must edit your u-boot.lds file to reflect this 1548configuration. 1549 1550 1551Low Level (hardware related) configuration options: 1552--------------------------------------------------- 1553 1554- CFG_CACHELINE_SIZE: 1555 Cache Line Size of the CPU. 1556 1557- CFG_DEFAULT_IMMR: 1558 Default address of the IMMR after system reset. 1559 Needed on some 8260 systems (MPC8260ADS and RPXsuper) 1560 to be able to adjust the position of the IMMR 1561 register after a reset. 1562 1563- Floppy Disk Support: 1564 CFG_FDC_DRIVE_NUMBER 1565 1566 the default drive number (default value 0) 1567 1568 CFG_ISA_IO_STRIDE 1569 1570 defines the spacing between fdc chipset registers 1571 (default value 1) 1572 1573 CFG_ISA_IO_OFFSET 1574 1575 defines the offset of register from address. It 1576 depends on which part of the data bus is connected to 1577 the fdc chipset. (default value 0) 1578 1579 If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and 1580 CFG_FDC_DRIVE_NUMBER are undefined, they take their 1581 default value. 1582 1583 if CFG_FDC_HW_INIT is defined, then the function 1584 fdc_hw_init() is called at the beginning of the FDC 1585 setup. fdc_hw_init() must be provided by the board 1586 source code. It is used to make hardware dependant 1587 initializations. 1588 1589- CFG_IMMR: Physical address of the Internal Memory Mapped 1590 Register; DO NOT CHANGE! (11-4) 1591 [MPC8xx systems only] 1592 1593- CFG_INIT_RAM_ADDR: 1594 1595 Start address of memory area tha can be used for 1596 initial data and stack; please note that this must be 1597 writable memory that is working WITHOUT special 1598 initialization, i. e. you CANNOT use normal RAM which 1599 will become available only after programming the 1600 memory controller and running certain initialization 1601 sequences. 1602 1603 U-Boot uses the following memory types: 1604 - MPC8xx and MPC8260: IMMR (internal memory of the CPU) 1605 - MPC824X: data cache 1606 - PPC4xx: data cache 1607 1608- CFG_INIT_DATA_OFFSET: 1609 1610 Offset of the initial data structure in the memory 1611 area defined by CFG_INIT_RAM_ADDR. Usually 1612 CFG_INIT_DATA_OFFSET is chosen such that the initial 1613 data is located at the end of the available space 1614 (sometimes written as (CFG_INIT_RAM_END - 1615 CFG_INIT_DATA_SIZE), and the initial stack is just 1616 below that area (growing from (CFG_INIT_RAM_ADDR + 1617 CFG_INIT_DATA_OFFSET) downward. 1618 1619 Note: 1620 On the MPC824X (or other systems that use the data 1621 cache for initial memory) the address chosen for 1622 CFG_INIT_RAM_ADDR is basically arbitrary - it must 1623 point to an otherwise UNUSED address space between 1624 the top of RAM and the start of the PCI space. 1625 1626- CFG_SIUMCR: SIU Module Configuration (11-6) 1627 1628- CFG_SYPCR: System Protection Control (11-9) 1629 1630- CFG_TBSCR: Time Base Status and Control (11-26) 1631 1632- CFG_PISCR: Periodic Interrupt Status and Control (11-31) 1633 1634- CFG_PLPRCR: PLL, Low-Power, and Reset Control Register (15-30) 1635 1636- CFG_SCCR: System Clock and reset Control Register (15-27) 1637 1638- CFG_OR_TIMING_SDRAM: 1639 SDRAM timing 1640 1641- CFG_MAMR_PTA: 1642 periodic timer for refresh 1643 1644- CFG_DER: Debug Event Register (37-47) 1645 1646- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM, 1647 CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP, 1648 CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM, 1649 CFG_BR1_PRELIM: 1650 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH) 1651 1652- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE, 1653 CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM, 1654 CFG_OR3_PRELIM, CFG_BR3_PRELIM: 1655 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM) 1656 1657- CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K, 1658 CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL: 1659 Machine Mode Register and Memory Periodic Timer 1660 Prescaler definitions (SDRAM timing) 1661 1662- CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]: 1663 enable I2C microcode relocation patch (MPC8xx); 1664 define relocation offset in DPRAM [DSP2] 1665 1666- CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]: 1667 enable SPI microcode relocation patch (MPC8xx); 1668 define relocation offset in DPRAM [SCC4] 1669 1670- CFG_USE_OSCCLK: 1671 Use OSCM clock mode on MBX8xx board. Be careful, 1672 wrong setting might damage your board. Read 1673 doc/README.MBX before setting this variable! 1674 1675- CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only) 1676 Offset of the bootmode word in DPRAM used by post 1677 (Power On Self Tests). This definition overrides 1678 #define'd default value in commproc.h resp. 1679 cpm_8260.h. 1680 1681Building the Software: 1682====================== 1683 1684Building U-Boot has been tested in native PPC environments (on a 1685PowerBook G3 running LinuxPPC 2000) and in cross environments 1686(running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and 1687NetBSD 1.5 on x86). 1688 1689If you are not using a native PPC environment, it is assumed that you 1690have the GNU cross compiling tools available in your path and named 1691with a prefix of "powerpc-linux-". If this is not the case, (e.g. if 1692you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change 1693the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU, 1694change it to: 1695 1696 CROSS_COMPILE = ppc_4xx- 1697 1698 1699U-Boot is intended to be simple to build. After installing the 1700sources you must configure U-Boot for one specific board type. This 1701is done by typing: 1702 1703 make NAME_config 1704 1705where "NAME_config" is the name of one of the existing 1706configurations; the following names are supported: 1707 1708 ADCIOP_config GTH_config TQM850L_config 1709 ADS860_config IP860_config TQM855L_config 1710 AR405_config IVML24_config TQM860L_config 1711 CANBT_config IVMS8_config WALNUT405_config 1712 CPCI405_config LANTEC_config cogent_common_config 1713 CPCIISER4_config MBX_config cogent_mpc8260_config 1714 CU824_config MBX860T_config cogent_mpc8xx_config 1715 ESTEEM192E_config RPXlite_config hermes_config 1716 ETX094_config RPXsuper_config hymod_config 1717 FADS823_config SM850_config lwmon_config 1718 FADS850SAR_config SPD823TS_config pcu_e_config 1719 FADS860T_config SXNI855T_config rsdproto_config 1720 FPS850L_config Sandpoint8240_config sbc8260_config 1721 GENIETV_config TQM823L_config PIP405_config 1722 GEN860T_config EBONY_config FPS860L_config 1723 ELPT860_config 1724 1725Note: for some board special configuration names may exist; check if 1726 additional information is available from the board vendor; for 1727 instance, the TQM8xxL systems run normally at 50 MHz and use a 1728 SCC for 10baseT ethernet; there are also systems with 80 MHz 1729 CPU clock, and an optional Fast Ethernet module is available 1730 for CPU's with FEC. You can select such additional "features" 1731 when chosing the configuration, i. e. 1732 1733 make TQM860L_config 1734 - will configure for a plain TQM860L, i. e. 50MHz, no FEC 1735 1736 make TQM860L_FEC_config 1737 - will configure for a TQM860L at 50MHz with FEC for ethernet 1738 1739 make TQM860L_80MHz_config 1740 - will configure for a TQM860L at 80 MHz, with normal 10baseT 1741 interface 1742 1743 make TQM860L_FEC_80MHz_config 1744 - will configure for a TQM860L at 80 MHz with FEC for ethernet 1745 1746 make TQM823L_LCD_config 1747 - will configure for a TQM823L with U-Boot console on LCD 1748 1749 make TQM823L_LCD_80MHz_config 1750 - will configure for a TQM823L at 80 MHz with U-Boot console on LCD 1751 1752 etc. 1753 1754 1755 1756Finally, type "make all", and you should get some working U-Boot 1757images ready for downlod to / installation on your system: 1758 1759- "u-boot.bin" is a raw binary image 1760- "u-boot" is an image in ELF binary format 1761- "u-boot.srec" is in Motorola S-Record format 1762 1763 1764Please be aware that the Makefiles assume you are using GNU make, so 1765for instance on NetBSD you might need to use "gmake" instead of 1766native "make". 1767 1768 1769If the system board that you have is not listed, then you will need 1770to port U-Boot to your hardware platform. To do this, follow these 1771steps: 1772 17731. Add a new configuration option for your board to the toplevel 1774 "Makefile", using the existing entries as examples. 17752. Create a new directory to hold your board specific code. Add any 1776 files you need. 17773. If you're porting U-Boot to a new CPU, then also create a new 1778 directory to hold your CPU specific code. Add any files you need. 17794. Run "make config_name" with your new name. 17805. Type "make", and you should get a working "u-boot.srec" file 1781 to be installed on your target system. 1782 [Of course, this last step is much harder than it sounds.] 1783 1784 1785Testing of U-Boot Modifications, Ports to New Hardware, etc.: 1786============================================================== 1787 1788If you have modified U-Boot sources (for instance added a new board 1789or support for new devices, a new CPU, etc.) you are expected to 1790provide feedback to the other developers. The feedback normally takes 1791the form of a "patch", i. e. a context diff against a certain (latest 1792official or latest in CVS) version of U-Boot sources. 1793 1794But before you submit such a patch, please verify that your modifi- 1795cation did not break existing code. At least make sure that *ALL* of 1796the supported boards compile WITHOUT ANY compiler warnings. To do so, 1797just run the "MAKEALL" script, which will configure and build U-Boot 1798for ALL supported system. Be warned, this will take a while. You can 1799select which (cross) compiler to use py passing a `CROSS_COMPILE' 1800environment variable to the script, i. e. to use the cross tools from 1801MontaVista's Hard Hat Linux you can type 1802 1803 CROSS_COMPILE=ppc_8xx- MAKEALL 1804 1805or to build on a native PowerPC system you can type 1806 1807 CROSS_COMPILE=' ' MAKEALL 1808 1809See also "U-Boot Porting Guide" below. 1810 1811 1812 1813Monitor Commands - Overview: 1814============================ 1815 1816go - start application at address 'addr' 1817run - run commands in an environment variable 1818bootm - boot application image from memory 1819bootp - boot image via network using BootP/TFTP protocol 1820tftpboot- boot image via network using TFTP protocol 1821 and env variables "ipaddr" and "serverip" 1822 (and eventually "gatewayip") 1823rarpboot- boot image via network using RARP/TFTP protocol 1824diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd' 1825loads - load S-Record file over serial line 1826loadb - load binary file over serial line (kermit mode) 1827md - memory display 1828mm - memory modify (auto-incrementing) 1829nm - memory modify (constant address) 1830mw - memory write (fill) 1831cp - memory copy 1832cmp - memory compare 1833crc32 - checksum calculation 1834imd - i2c memory display 1835imm - i2c memory modify (auto-incrementing) 1836inm - i2c memory modify (constant address) 1837imw - i2c memory write (fill) 1838icrc32 - i2c checksum calculation 1839iprobe - probe to discover valid I2C chip addresses 1840iloop - infinite loop on address range 1841isdram - print SDRAM configuration information 1842sspi - SPI utility commands 1843base - print or set address offset 1844printenv- print environment variables 1845setenv - set environment variables 1846saveenv - save environment variables to persistent storage 1847protect - enable or disable FLASH write protection 1848erase - erase FLASH memory 1849flinfo - print FLASH memory information 1850bdinfo - print Board Info structure 1851iminfo - print header information for application image 1852coninfo - print console devices and informations 1853ide - IDE sub-system 1854loop - infinite loop on address range 1855mtest - simple RAM test 1856icache - enable or disable instruction cache 1857dcache - enable or disable data cache 1858reset - Perform RESET of the CPU 1859echo - echo args to console 1860version - print monitor version 1861help - print online help 1862? - alias for 'help' 1863 1864 1865Monitor Commands - Detailed Description: 1866======================================== 1867 1868TODO. 1869 1870For now: just type "help <command>". 1871 1872 1873Environment Variables: 1874====================== 1875 1876U-Boot supports user configuration using Environment Variables which 1877can be made persistent by saving to Flash memory. 1878 1879Environment Variables are set using "setenv", printed using 1880"printenv", and saved to Flash using "saveenv". Using "setenv" 1881without a value can be used to delete a variable from the 1882environment. As long as you don't save the environment you are 1883working with an in-memory copy. In case the Flash area containing the 1884environment is erased by accident, a default environment is provided. 1885 1886Some configuration options can be set using Environment Variables: 1887 1888 baudrate - see CONFIG_BAUDRATE 1889 1890 bootdelay - see CONFIG_BOOTDELAY 1891 1892 bootcmd - see CONFIG_BOOTCOMMAND 1893 1894 bootargs - Boot arguments when booting an RTOS image 1895 1896 bootfile - Name of the image to load with TFTP 1897 1898 autoload - if set to "no" (any string beginning with 'n'), 1899 "bootp" will just load perform a lookup of the 1900 configuration from the BOOTP server, but not try to 1901 load any image using TFTP 1902 1903 autostart - if set to "yes", an image loaded using the "bootp", 1904 "rarpboot", "tftpboot" or "diskboot" commands will 1905 be automatically started (by internally calling 1906 "bootm") 1907 1908 initrd_high - restrict positioning of initrd images: 1909 If this variable is not set, initrd images will be 1910 copied to the highest possible address in RAM; this 1911 is usually what you want since it allows for 1912 maximum initrd size. If for some reason you want to 1913 make sure that the initrd image is loaded below the 1914 CFG_BOOTMAPSZ limit, you can set this environment 1915 variable to a value of "no" or "off" or "0". 1916 Alternatively, you can set it to a maximum upper 1917 address to use (U-Boot will still check that it 1918 does not overwrite the U-Boot stack and data). 1919 1920 For instance, when you have a system with 16 MB 1921 RAM, and want to reseve 4 MB from use by Linux, 1922 you can do this by adding "mem=12M" to the value of 1923 the "bootargs" variable. However, now you must make 1924 sure, that the initrd image is placed in the first 1925 12 MB as well - this can be done with 1926 1927 setenv initrd_high 00c00000 1928 1929 ipaddr - IP address; needed for tftpboot command 1930 1931 loadaddr - Default load address for commands like "bootp", 1932 "rarpboot", "tftpboot", "loadb" or "diskboot" 1933 1934 loads_echo - see CONFIG_LOADS_ECHO 1935 1936 serverip - TFTP server IP address; needed for tftpboot command 1937 1938 bootretry - see CONFIG_BOOT_RETRY_TIME 1939 1940 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR 1941 1942 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR 1943 1944 1945The following environment variables may be used and automatically 1946updated by the network boot commands ("bootp" and "rarpboot"), 1947depending the information provided by your boot server: 1948 1949 bootfile - see above 1950 dnsip - IP address of your Domain Name Server 1951 gatewayip - IP address of the Gateway (Router) to use 1952 hostname - Target hostname 1953 ipaddr - see above 1954 netmask - Subnet Mask 1955 rootpath - Pathname of the root filesystem on the NFS server 1956 serverip - see above 1957 1958 1959There are two special Environment Variables: 1960 1961 serial# - contains hardware identification information such 1962 as type string and/or serial number 1963 ethaddr - Ethernet address 1964 1965These variables can be set only once (usually during manufacturing of 1966the board). U-Boot refuses to delete or overwrite these variables 1967once they have been set once. 1968 1969 1970Please note that changes to some configuration parameters may take 1971only effect after the next boot (yes, that's just like Windoze :-). 1972 1973 1974Note for Redundant Ethernet Interfaces: 1975======================================= 1976 1977Some boards come with redundand ethernet interfaces; U-Boot supports 1978such configurations and is capable of automatic selection of a 1979"working" interface when needed. MAC assignemnt works as follows: 1980 1981Network interfaces are numbered eth0, eth1, eth2, ... Corresponding 1982MAC addresses can be stored in the environment as "ethaddr" (=>eth0), 1983"eth1addr" (=>eth1), "eth2addr", ... 1984 1985If the network interface stores some valid MAC address (for instance 1986in SROM), this is used as default address if there is NO correspon- 1987ding setting in the environment; if the corresponding environment 1988variable is set, this overrides the settings in the card; that means: 1989 1990o If the SROM has a valid MAC address, and there is no address in the 1991 environment, the SROM's address is used. 1992 1993o If there is no valid address in the SROM, and a definition in the 1994 environment exists, then the value from the environment variable is 1995 used. 1996 1997o If both the SROM and the environment contain a MAC address, and 1998 both addresses are the same, this MAC address is used. 1999 2000o If both the SROM and the environment contain a MAC address, and the 2001 addresses differ, the value from the environment is used and a 2002 warning is printed. 2003 2004o If neither SROM nor the environment contain a MAC address, an error 2005 is raised. 2006 2007 2008 2009Image Formats: 2010============== 2011 2012The "boot" commands of this monitor operate on "image" files which 2013can be basicly anything, preceeded by a special header; see the 2014definitions in include/image.h for details; basicly, the header 2015defines the following image properties: 2016 2017* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD, 2018 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks, 2019 LynxOS, pSOS, QNX; 2020 Currently supported: Linux, NetBSD, VxWorks, QNX). 2021* Target CPU Architecture (Provisions for Alpha, ARM, Intel x86, 2022 IA64, MIPS, MIPS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit; 2023 Currently supported: PowerPC). 2024* Compression Type (Provisions for uncompressed, gzip, bzip2; 2025 Currently supported: uncompressed, gzip). 2026* Load Address 2027* Entry Point 2028* Image Name 2029* Image Timestamp 2030 2031The header is marked by a special Magic Number, and both the header 2032and the data portions of the image are secured against corruption by 2033CRC32 checksums. 2034 2035 2036Linux Support: 2037============== 2038 2039Although U-Boot should support any OS or standalone application 2040easily, Linux has always been in the focus during the design of 2041U-Boot. 2042 2043U-Boot includes many features that so far have been part of some 2044special "boot loader" code within the Linux kernel. Also, any 2045"initrd" images to be used are no longer part of one big Linux image; 2046instead, kernel and "initrd" are separate images. This implementation 2047serves serveral purposes: 2048 2049- the same features can be used for other OS or standalone 2050 applications (for instance: using compressed images to reduce the 2051 Flash memory footprint) 2052 2053- it becomes much easier to port new Linux kernel versions because 2054 lots of low-level, hardware dependend stuff are done by U-Boot 2055 2056- the same Linux kernel image can now be used with different "initrd" 2057 images; of course this also means that different kernel images can 2058 be run with the same "initrd". This makes testing easier (you don't 2059 have to build a new "zImage.initrd" Linux image when you just 2060 change a file in your "initrd"). Also, a field-upgrade of the 2061 software is easier now. 2062 2063 2064Linux HOWTO: 2065============ 2066 2067Porting Linux to U-Boot based systems: 2068--------------------------------------- 2069 2070U-Boot cannot save you from doing all the necessary modifications to 2071configure the Linux device drivers for use with your target hardware 2072(no, we don't intend to provide a full virtual machine interface to 2073Linux :-). 2074 2075But now you can ignore ALL boot loader code (in arch/ppc/mbxboot). 2076 2077Just make sure your machine specific header file (for instance 2078include/asm-ppc/tqm8xx.h) includes the same definition of the Board 2079Information structure as we define in include/u-boot.h, and make 2080sure that your definition of IMAP_ADDR uses the same value as your 2081U-Boot configuration in CFG_IMMR. 2082 2083 2084Configuring the Linux kernel: 2085----------------------------- 2086 2087No specific requirements for U-Boot. Make sure you have some root 2088device (initial ramdisk, NFS) for your target system. 2089 2090 2091Building a Linux Image: 2092----------------------- 2093 2094With U-Boot, "normal" build targets like "zImage" or "bzImage" are 2095not used. If you use recent kernel source, a new build target 2096"uImage" will exist which automatically builds an image usable by 2097U-Boot. Most older kernels also have support for a "pImage" target, 2098which was introduced for our predecessor project PPCBoot and uses a 2099100% compatible format. 2100 2101Example: 2102 2103 make TQM850L_config 2104 make oldconfig 2105 make dep 2106 make uImage 2107 2108The "uImage" build target uses a special tool (in 'tools/mkimage') to 2109encapsulate a compressed Linux kernel image with header information, 2110CRC32 checksum etc. for use with U-Boot. This is what we are doing: 2111 2112* build a standard "vmlinux" kernel image (in ELF binary format): 2113 2114* convert the kernel into a raw binary image: 2115 2116 ${CROSS_COMPILE}-objcopy -O binary \ 2117 -R .note -R .comment \ 2118 -S vmlinux linux.bin 2119 2120* compress the binary image: 2121 2122 gzip -9 linux.bin 2123 2124* package compressed binary image for U-Boot: 2125 2126 mkimage -A ppc -O linux -T kernel -C gzip \ 2127 -a 0 -e 0 -n "Linux Kernel Image" \ 2128 -d linux.bin.gz uImage 2129 2130 2131The "mkimage" tool can also be used to create ramdisk images for use 2132with U-Boot, either separated from the Linux kernel image, or 2133combined into one file. "mkimage" encapsulates the images with a 64 2134byte header containing information about target architecture, 2135operating system, image type, compression method, entry points, time 2136stamp, CRC32 checksums, etc. 2137 2138"mkimage" can be called in two ways: to verify existing images and 2139print the header information, or to build new images. 2140 2141In the first form (with "-l" option) mkimage lists the information 2142contained in the header of an existing U-Boot image; this includes 2143checksum verification: 2144 2145 tools/mkimage -l image 2146 -l ==> list image header information 2147 2148The second form (with "-d" option) is used to build a U-Boot image 2149from a "data file" which is used as image payload: 2150 2151 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \ 2152 -n name -d data_file image 2153 -A ==> set architecture to 'arch' 2154 -O ==> set operating system to 'os' 2155 -T ==> set image type to 'type' 2156 -C ==> set compression type 'comp' 2157 -a ==> set load address to 'addr' (hex) 2158 -e ==> set entry point to 'ep' (hex) 2159 -n ==> set image name to 'name' 2160 -d ==> use image data from 'datafile' 2161 2162Right now, all Linux kernels use the same load address (0x00000000), 2163but the entry point address depends on the kernel version: 2164 2165- 2.2.x kernels have the entry point at 0x0000000C, 2166- 2.3.x and later kernels have the entry point at 0x00000000. 2167 2168So a typical call to build a U-Boot image would read: 2169 2170 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \ 2171 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \ 2172 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \ 2173 > examples/uImage.TQM850L 2174 Image Name: 2.4.4 kernel for TQM850L 2175 Created: Wed Jul 19 02:34:59 2000 2176 Image Type: PowerPC Linux Kernel Image (gzip compressed) 2177 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB 2178 Load Address: 0x00000000 2179 Entry Point: 0x00000000 2180 2181To verify the contents of the image (or check for corruption): 2182 2183 -> tools/mkimage -l examples/uImage.TQM850L 2184 Image Name: 2.4.4 kernel for TQM850L 2185 Created: Wed Jul 19 02:34:59 2000 2186 Image Type: PowerPC Linux Kernel Image (gzip compressed) 2187 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB 2188 Load Address: 0x00000000 2189 Entry Point: 0x00000000 2190 2191NOTE: for embedded systems where boot time is critical you can trade 2192speed for memory and install an UNCOMPRESSED image instead: this 2193needs more space in Flash, but boots much faster since it does not 2194need to be uncompressed: 2195 2196 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz 2197 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \ 2198 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \ 2199 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \ 2200 > examples/uImage.TQM850L-uncompressed 2201 Image Name: 2.4.4 kernel for TQM850L 2202 Created: Wed Jul 19 02:34:59 2000 2203 Image Type: PowerPC Linux Kernel Image (uncompressed) 2204 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB 2205 Load Address: 0x00000000 2206 Entry Point: 0x00000000 2207 2208 2209Similar you can build U-Boot images from a 'ramdisk.image.gz' file 2210when your kernel is intended to use an initial ramdisk: 2211 2212 -> tools/mkimage -n 'Simple Ramdisk Image' \ 2213 > -A ppc -O linux -T ramdisk -C gzip \ 2214 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd 2215 Image Name: Simple Ramdisk Image 2216 Created: Wed Jan 12 14:01:50 2000 2217 Image Type: PowerPC Linux RAMDisk Image (gzip compressed) 2218 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB 2219 Load Address: 0x00000000 2220 Entry Point: 0x00000000 2221 2222 2223Installing a Linux Image: 2224------------------------- 2225 2226To downloading a U-Boot image over the serial (console) interface, 2227you must convert the image to S-Record format: 2228 2229 objcopy -I binary -O srec examples/image examples/image.srec 2230 2231The 'objcopy' does not understand the information in the U-Boot 2232image header, so the resulting S-Record file will be relative to 2233address 0x00000000. To load it to a given address, you need to 2234specify the target address as 'offset' parameter with the 'loads' 2235command. 2236 2237Example: install the image to address 0x40100000 (which on the 2238TQM8xxL is in the first Flash bank): 2239 2240 => erase 40100000 401FFFFF 2241 2242 .......... done 2243 Erased 8 sectors 2244 2245 => loads 40100000 2246 ## Ready for S-Record download ... 2247 ~>examples/image.srec 2248 1 2 3 4 5 6 7 8 9 10 11 12 13 ... 2249 ... 2250 15989 15990 15991 15992 2251 [file transfer complete] 2252 [connected] 2253 ## Start Addr = 0x00000000 2254 2255 2256You can check the success of the download using the 'iminfo' command; 2257this includes a checksum verification so you can be sure no data 2258corruption happened: 2259 2260 => imi 40100000 2261 2262 ## Checking Image at 40100000 ... 2263 Image Name: 2.2.13 for initrd on TQM850L 2264 Image Type: PowerPC Linux Kernel Image (gzip compressed) 2265 Data Size: 335725 Bytes = 327 kB = 0 MB 2266 Load Address: 00000000 2267 Entry Point: 0000000c 2268 Verifying Checksum ... OK 2269 2270 2271 2272Boot Linux: 2273----------- 2274 2275The "bootm" command is used to boot an application that is stored in 2276memory (RAM or Flash). In case of a Linux kernel image, the contents 2277of the "bootargs" environment variable is passed to the kernel as 2278parameters. You can check and modify this variable using the 2279"printenv" and "setenv" commands: 2280 2281 2282 => printenv bootargs 2283 bootargs=root=/dev/ram 2284 2285 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2 2286 2287 => printenv bootargs 2288 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2 2289 2290 => bootm 40020000 2291 ## Booting Linux kernel at 40020000 ... 2292 Image Name: 2.2.13 for NFS on TQM850L 2293 Image Type: PowerPC Linux Kernel Image (gzip compressed) 2294 Data Size: 381681 Bytes = 372 kB = 0 MB 2295 Load Address: 00000000 2296 Entry Point: 0000000c 2297 Verifying Checksum ... OK 2298 Uncompressing Kernel Image ... OK 2299 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 2300 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2 2301 time_init: decrementer frequency = 187500000/60 2302 Calibrating delay loop... 49.77 BogoMIPS 2303 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000] 2304 ... 2305 2306If you want to boot a Linux kernel with initial ram disk, you pass 2307the memory addreses of both the kernel and the initrd image (PPBCOOT 2308format!) to the "bootm" command: 2309 2310 => imi 40100000 40200000 2311 2312 ## Checking Image at 40100000 ... 2313 Image Name: 2.2.13 for initrd on TQM850L 2314 Image Type: PowerPC Linux Kernel Image (gzip compressed) 2315 Data Size: 335725 Bytes = 327 kB = 0 MB 2316 Load Address: 00000000 2317 Entry Point: 0000000c 2318 Verifying Checksum ... OK 2319 2320 ## Checking Image at 40200000 ... 2321 Image Name: Simple Ramdisk Image 2322 Image Type: PowerPC Linux RAMDisk Image (gzip compressed) 2323 Data Size: 566530 Bytes = 553 kB = 0 MB 2324 Load Address: 00000000 2325 Entry Point: 00000000 2326 Verifying Checksum ... OK 2327 2328 => bootm 40100000 40200000 2329 ## Booting Linux kernel at 40100000 ... 2330 Image Name: 2.2.13 for initrd on TQM850L 2331 Image Type: PowerPC Linux Kernel Image (gzip compressed) 2332 Data Size: 335725 Bytes = 327 kB = 0 MB 2333 Load Address: 00000000 2334 Entry Point: 0000000c 2335 Verifying Checksum ... OK 2336 Uncompressing Kernel Image ... OK 2337 ## Loading RAMDisk Image at 40200000 ... 2338 Image Name: Simple Ramdisk Image 2339 Image Type: PowerPC Linux RAMDisk Image (gzip compressed) 2340 Data Size: 566530 Bytes = 553 kB = 0 MB 2341 Load Address: 00000000 2342 Entry Point: 00000000 2343 Verifying Checksum ... OK 2344 Loading Ramdisk ... OK 2345 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 2346 Boot arguments: root=/dev/ram 2347 time_init: decrementer frequency = 187500000/60 2348 Calibrating delay loop... 49.77 BogoMIPS 2349 ... 2350 RAMDISK: Compressed image found at block 0 2351 VFS: Mounted root (ext2 filesystem). 2352 2353 bash# 2354 2355More About U-Boot Image Types: 2356------------------------------ 2357 2358U-Boot supports the following image types: 2359 2360 "Standalone Programs" are directly runnable in the environment 2361 provided by U-Boot; it is expected that (if they behave 2362 well) you can continue to work in U-Boot after return from 2363 the Standalone Program. 2364 "OS Kernel Images" are usually images of some Embedded OS which 2365 will take over control completely. Usually these programs 2366 will install their own set of exception handlers, device 2367 drivers, set up the MMU, etc. - this means, that you cannot 2368 expect to re-enter U-Boot except by resetting the CPU. 2369 "RAMDisk Images" are more or less just data blocks, and their 2370 parameters (address, size) are passed to an OS kernel that is 2371 being started. 2372 "Multi-File Images" contain several images, typically an OS 2373 (Linux) kernel image and one or more data images like 2374 RAMDisks. This construct is useful for instance when you want 2375 to boot over the network using BOOTP etc., where the boot 2376 server provides just a single image file, but you want to get 2377 for instance an OS kernel and a RAMDisk image. 2378 2379 "Multi-File Images" start with a list of image sizes, each 2380 image size (in bytes) specified by an "uint32_t" in network 2381 byte order. This list is terminated by an "(uint32_t)0". 2382 Immediately after the terminating 0 follow the images, one by 2383 one, all aligned on "uint32_t" boundaries (size rounded up to 2384 a multiple of 4 bytes). 2385 2386 "Firmware Images" are binary images containing firmware (like 2387 U-Boot or FPGA images) which usually will be programmed to 2388 flash memory. 2389 2390 "Script files" are command sequences that will be executed by 2391 U-Boot's command interpreter; this feature is especially 2392 useful when you configure U-Boot to use a real shell (hush) 2393 as command interpreter. 2394 2395 2396Standalone HOWTO: 2397================= 2398 2399One of the features of U-Boot is that you can dynamically load and 2400run "standalone" applications, which can use some resources of 2401U-Boot like console I/O functions or interrupt services. 2402 2403Two simple examples are included with the sources: 2404 2405"Hello World" Demo: 2406------------------- 2407 2408'examples/hello_world.c' contains a small "Hello World" Demo 2409application; it is automatically compiled when you build U-Boot. 2410It's configured to run at address 0x00040004, so you can play with it 2411like that: 2412 2413 => loads 2414 ## Ready for S-Record download ... 2415 ~>examples/hello_world.srec 2416 1 2 3 4 5 6 7 8 9 10 11 ... 2417 [file transfer complete] 2418 [connected] 2419 ## Start Addr = 0x00040004 2420 2421 => go 40004 Hello World! This is a test. 2422 ## Starting application at 0x00040004 ... 2423 Hello World 2424 argc = 7 2425 argv[0] = "40004" 2426 argv[1] = "Hello" 2427 argv[2] = "World!" 2428 argv[3] = "This" 2429 argv[4] = "is" 2430 argv[5] = "a" 2431 argv[6] = "test." 2432 argv[7] = "<NULL>" 2433 Hit any key to exit ... 2434 2435 ## Application terminated, rc = 0x0 2436 2437Another example, which demonstrates how to register a CPM interrupt 2438handler with the U-Boot code, can be found in 'examples/timer.c'. 2439Here, a CPM timer is set up to generate an interrupt every second. 2440The interrupt service routine is trivial, just printing a '.' 2441character, but this is just a demo program. The application can be 2442controlled by the following keys: 2443 2444 ? - print current values og the CPM Timer registers 2445 b - enable interrupts and start timer 2446 e - stop timer and disable interrupts 2447 q - quit application 2448 2449 => loads 2450 ## Ready for S-Record download ... 2451 ~>examples/timer.srec 2452 1 2 3 4 5 6 7 8 9 10 11 ... 2453 [file transfer complete] 2454 [connected] 2455 ## Start Addr = 0x00040004 2456 2457 => go 40004 2458 ## Starting application at 0x00040004 ... 2459 TIMERS=0xfff00980 2460 Using timer 1 2461 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0 2462 2463Hit 'b': 2464 [q, b, e, ?] Set interval 1000000 us 2465 Enabling timer 2466Hit '?': 2467 [q, b, e, ?] ........ 2468 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0 2469Hit '?': 2470 [q, b, e, ?] . 2471 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0 2472Hit '?': 2473 [q, b, e, ?] . 2474 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0 2475Hit '?': 2476 [q, b, e, ?] . 2477 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0 2478Hit 'e': 2479 [q, b, e, ?] ...Stopping timer 2480Hit 'q': 2481 [q, b, e, ?] ## Application terminated, rc = 0x0 2482 2483 2484NetBSD Notes: 2485============= 2486 2487Starting at version 0.9.2, U-Boot supports NetBSD both as host 2488(build U-Boot) and target system (boots NetBSD/mpc8xx). 2489 2490Building requires a cross environment; it is known to work on 2491NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also 2492need gmake since the Makefiles are not compatible with BSD make). 2493Note that the cross-powerpc package does not install include files; 2494attempting to build U-Boot will fail because <machine/ansi.h> is 2495missing. This file has to be installed and patched manually: 2496 2497 # cd /usr/pkg/cross/powerpc-netbsd/include 2498 # mkdir powerpc 2499 # ln -s powerpc machine 2500 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h 2501 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST 2502 2503Native builds *don't* work due to incompatibilities between native 2504and U-Boot include files. 2505 2506Booting assumes that (the first part of) the image booted is a 2507stage-2 loader which in turn loads and then invokes the kernel 2508proper. Loader sources will eventually appear in the NetBSD source 2509tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the 2510meantime, send mail to bruno@exet-ag.de and/or wd@denx.de for 2511details. 2512 2513 2514Implementation Internals: 2515========================= 2516 2517The following is not intended to be a complete description of every 2518implementation detail. However, it should help to understand the 2519inner workings of U-Boot and make it easier to port it to custom 2520hardware. 2521 2522 2523Initial Stack, Global Data: 2524--------------------------- 2525 2526The implementation of U-Boot is complicated by the fact that U-Boot 2527starts running out of ROM (flash memory), usually without access to 2528system RAM (because the memory controller is not initialized yet). 2529This means that we don't have writable Data or BSS segments, and BSS 2530is not initialized as zero. To be able to get a C environment working 2531at all, we have to allocate at least a minimal stack. Implementation 2532options for this are defined and restricted by the CPU used: Some CPU 2533models provide on-chip memory (like the IMMR area on MPC8xx and 2534MPC826x processors), on others (parts of) the data cache can be 2535locked as (mis-) used as memory, etc. 2536 2537 Chris Hallinan posted a good summy of these issues to the 2538 u-boot-users mailing list: 2539 2540 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)? 2541 From: "Chris Hallinan" <clh@net1plus.com> 2542 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET) 2543 ... 2544 2545 Correct me if I'm wrong, folks, but the way I understand it 2546 is this: Using DCACHE as initial RAM for Stack, etc, does not 2547 require any physical RAM backing up the cache. The cleverness 2548 is that the cache is being used as a temporary supply of 2549 necessary storage before the SDRAM controller is setup. It's 2550 beyond the scope of this list to expain the details, but you 2551 can see how this works by studying the cache architecture and 2552 operation in the architecture and processor-specific manuals. 2553 2554 OCM is On Chip Memory, which I believe the 405GP has 4K. It 2555 is another option for the system designer to use as an 2556 initial stack/ram area prior to SDRAM being available. Either 2557 option should work for you. Using CS 4 should be fine if your 2558 board designers haven't used it for something that would 2559 cause you grief during the initial boot! It is frequently not 2560 used. 2561 2562 CFG_INIT_RAM_ADDR should be somewhere that won't interfere 2563 with your processor/board/system design. The default value 2564 you will find in any recent u-boot distribution in 2565 Walnut405.h should work for you. I'd set it to a value larger 2566 than your SDRAM module. If you have a 64MB SDRAM module, set 2567 it above 400_0000. Just make sure your board has no resources 2568 that are supposed to respond to that address! That code in 2569 start.S has been around a while and should work as is when 2570 you get the config right. 2571 2572 -Chris Hallinan 2573 DS4.COM, Inc. 2574 2575It is essential to remember this, since it has some impact on the C 2576code for the initialization procedures: 2577 2578* Initialized global data (data segment) is read-only. Do not attempt 2579 to write it. 2580 2581* Do not use any unitialized global data (or implicitely initialized 2582 as zero data - BSS segment) at all - this is undefined, initiali- 2583 zation is performed later (when relocationg to RAM). 2584 2585* Stack space is very limited. Avoid big data buffers or things like 2586 that. 2587 2588Having only the stack as writable memory limits means we cannot use 2589normal global data to share information beween the code. But it 2590turned out that the implementation of U-Boot can be greatly 2591simplified by making a global data structure (gd_t) available to all 2592functions. We could pass a pointer to this data as argument to _all_ 2593functions, but this would bloat the code. Instead we use a feature of 2594the GCC compiler (Global Register Variables) to share the data: we 2595place a pointer (gd) to the global data into a register which we 2596reserve for this purpose. 2597 2598When chosing a register for such a purpose we are restricted by the 2599relevant (E)ABI specifications for the current architecture, and by 2600GCC's implementation. 2601 2602For PowerPC, the following registers have specific use: 2603 R1: stack pointer 2604 R2: TOC pointer 2605 R3-R4: parameter passing and return values 2606 R5-R10: parameter passing 2607 R13: small data area pointer 2608 R30: GOT pointer 2609 R31: frame pointer 2610 2611 (U-Boot also uses R14 as internal GOT pointer.) 2612 2613 ==> U-Boot will use R29 to hold a pointer to the global data 2614 2615 Note: on PPC, we could use a static initializer (since the 2616 address of the global data structure is known at compile time), 2617 but it turned out that reserving a register results in somewhat 2618 smaller code - although the code savings are not that big (on 2619 average for all boards 752 bytes for the whole U-Boot image, 2620 624 text + 127 data). 2621 2622On ARM, the following registers are used: 2623 2624 R0: function argument word/integer result 2625 R1-R3: function argument word 2626 R9: GOT pointer 2627 R10: stack limit (used only if stack checking if enabled) 2628 R11: argument (frame) pointer 2629 R12: temporary workspace 2630 R13: stack pointer 2631 R14: link register 2632 R15: program counter 2633 2634 ==> U-Boot will use R8 to hold a pointer to the global data 2635 2636 2637 2638Memory Management: 2639------------------ 2640 2641U-Boot runs in system state and uses physical addresses, i.e. the 2642MMU is not used either for address mapping nor for memory protection. 2643 2644The available memory is mapped to fixed addresses using the memory 2645controller. In this process, a contiguous block is formed for each 2646memory type (Flash, SDRAM, SRAM), even when it consists of several 2647physical memory banks. 2648 2649U-Boot is installed in the first 128 kB of the first Flash bank (on 2650TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After 2651booting and sizing and initializing DRAM, the code relocates itself 2652to the upper end of DRAM. Immediately below the U-Boot code some 2653memory is reserved for use by malloc() [see CFG_MALLOC_LEN 2654configuration setting]. Below that, a structure with global Board 2655Info data is placed, followed by the stack (growing downward). 2656 2657Additionally, some exception handler code is copied to the low 8 kB 2658of DRAM (0x00000000 ... 0x00001FFF). 2659 2660So a typical memory configuration with 16 MB of DRAM could look like 2661this: 2662 2663 0x0000 0000 Exception Vector code 2664 : 2665 0x0000 1FFF 2666 0x0000 2000 Free for Application Use 2667 : 2668 : 2669 2670 : 2671 : 2672 0x00FB FF20 Monitor Stack (Growing downward) 2673 0x00FB FFAC Board Info Data and permanent copy of global data 2674 0x00FC 0000 Malloc Arena 2675 : 2676 0x00FD FFFF 2677 0x00FE 0000 RAM Copy of Monitor Code 2678 ... eventually: LCD or video framebuffer 2679 ... eventually: pRAM (Protected RAM - unchanged by reset) 2680 0x00FF FFFF [End of RAM] 2681 2682 2683System Initialization: 2684---------------------- 2685 2686In the reset configuration, U-Boot starts at the reset entry point 2687(on most PowerPC systens at address 0x00000100). Because of the reset 2688configuration for CS0# this is a mirror of the onboard Flash memory. 2689To be able to re-map memory U-Boot then jumps to it's link address. 2690To be able to implement the initialization code in C, a (small!) 2691initial stack is set up in the internal Dual Ported RAM (in case CPUs 2692which provide such a feature like MPC8xx or MPC8260), or in a locked 2693part of the data cache. After that, U-Boot initializes the CPU core, 2694the caches and the SIU. 2695 2696Next, all (potentially) available memory banks are mapped using a 2697preliminary mapping. For example, we put them on 512 MB boundaries 2698(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash 2699on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is 2700programmed for SDRAM access. Using the temporary configuration, a 2701simple memory test is run that determines the size of the SDRAM 2702banks. 2703 2704When there is more than one SDRAM bank, and the banks are of 2705different size, the larger is mapped first. For equal size, the first 2706bank (CS2#) is mapped first. The first mapping is always for address 27070x00000000, with any additional banks following immediately to create 2708contiguous memory starting from 0. 2709 2710Then, the monitor installs itself at the upper end of the SDRAM area 2711and allocates memory for use by malloc() and for the global Board 2712Info data; also, the exception vector code is copied to the low RAM 2713pages, and the final stack is set up. 2714 2715Only after this relocation will you have a "normal" C environment; 2716until that you are restricted in several ways, mostly because you are 2717running from ROM, and because the code will have to be relocated to a 2718new address in RAM. 2719 2720 2721U-Boot Porting Guide: 2722---------------------- 2723 2724[Based on messages by Jerry Van Baren in the U-Boot-Users mailing 2725list, October 2002] 2726 2727 2728int main (int argc, char *argv[]) 2729{ 2730 sighandler_t no_more_time; 2731 2732 signal (SIGALRM, no_more_time); 2733 alarm (PROJECT_DEADLINE - toSec (3 * WEEK)); 2734 2735 if (available_money > available_manpower) { 2736 pay consultant to port U-Boot; 2737 return 0; 2738 } 2739 2740 Download latest U-Boot source; 2741 2742 Subscribe to u-boot-users mailing list; 2743 2744 if (clueless) { 2745 email ("Hi, I am new to U-Boot, how do I get started?"); 2746 } 2747 2748 while (learning) { 2749 Read the README file in the top level directory; 2750 Read http://www.denx.de/re/DPLG.html 2751 Read the source, Luke; 2752 } 2753 2754 if (available_money > toLocalCurrency ($2500)) { 2755 Buy a BDI2000; 2756 } else { 2757 Add a lot of aggravation and time; 2758 } 2759 2760 Create your own board support subdirectory; 2761 2762 Create your own board config file; 2763 2764 while (!running) { 2765 do { 2766 Add / modify source code; 2767 } until (compiles); 2768 Debug; 2769 if (clueless) 2770 email ("Hi, I am having problems..."); 2771 } 2772 Send patch file to Wolfgang; 2773 2774 return 0; 2775} 2776 2777void no_more_time (int sig) 2778{ 2779 hire_a_guru(); 2780} 2781 2782 2783 2784Coding Standards: 2785----------------- 2786 2787All contributions to U-Boot should conform to the Linux kernel 2788coding style; see the file "Documentation/CodingStyle" in your Linux 2789kernel source directory. 2790 2791Please note that U-Boot is implemented in C (and to some small parts 2792in Assembler); no C++ is used, so please do not use C++ style 2793comments (//) in your code. 2794 2795Submissions which do not conform to the standards may be returned 2796with a request to reformat the changes. 2797 2798 2799Submitting Patches: 2800------------------- 2801 2802Since the number of patches for U-Boot is growing, we need to 2803establish some rules. Submissions which do not conform to these rules 2804may be rejected, even when they contain important and valuable stuff. 2805 2806 2807When you send a patch, please include the following information with 2808it: 2809 2810* For bug fixes: a description of the bug and how your patch fixes 2811 this bug. Please try to include a way of demonstrating that the 2812 patch actually fixes something. 2813 2814* For new features: a description of the feature and your 2815 implementation. 2816 2817* A CHANGELOG entry as plaintext (separate from the patch) 2818 2819* For major contributions, your entry to the CREDITS file 2820 2821* When you add support for a new board, don't forget to add this 2822 board to the MAKEALL script, too. 2823 2824* If your patch adds new configuration options, don't forget to 2825 document these in the README file. 2826 2827* The patch itself. If you are accessing the CVS repository use "cvs 2828 update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your 2829 version of diff does not support these options, then get the latest 2830 version of GNU diff. 2831 2832 We accept patches as plain text, MIME attachments or as uuencoded 2833 gzipped text. 2834 2835Notes: 2836 2837* Before sending the patch, run the MAKEALL script on your patched 2838 source tree and make sure that no errors or warnings are reported 2839 for any of the boards. 2840 2841* Keep your modifications to the necessary minimum: A patch 2842 containing several unrelated changes or arbitrary reformats will be 2843 returned with a request to re-formatting / split it. 2844 2845* If you modify existing code, make sure that your new code does not 2846 add to the memory footprint of the code ;-) Small is beautiful! 2847 When adding new features, these should compile conditionally only 2848 (using #ifdef), and the resulting code with the new feature 2849 disabled must not need more memory than the old code without your 2850 modification. 2851