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 107Directory Hierarchy: 108==================== 109 110- board Board dependend files 111- common Misc architecture independend functions 112- cpu CPU specific files 113- disk Code for disk drive partition handling 114- doc Documentation (don't expect too much) 115- drivers Common used device drivers 116- dtt Digital Thermometer and Thermostat drivers 117- examples Example code for standalone applications, etc. 118- include Header Files 119- disk Harddisk interface code 120- net Networking code 121- ppc Files generic to PowerPC architecture 122- post Power On Self Test 123- post/arch Symlink to architecture specific Power On Self Test 124- post/arch-ppc PowerPC architecture specific Power On Self Test 125- post/cpu/mpc8260 MPC8260 CPU specific Power On Self Test 126- post/cpu/mpc8xx MPC8xx CPU specific Power On Self Test 127- rtc Real Time Clock drivers 128- tools Tools to build S-Record or U-Boot images, etc. 129 130- cpu/74xx_7xx Files specific to Motorola MPC74xx and 7xx CPUs 131- cpu/mpc8xx Files specific to Motorola MPC8xx CPUs 132- cpu/mpc824x Files specific to Motorola MPC824x CPUs 133- cpu/mpc8260 Files specific to Motorola MPC8260 CPU 134- cpu/ppc4xx Files specific to IBM 4xx CPUs 135 136- board/RPXClassic 137 Files specific to RPXClassic boards 138- board/RPXlite Files specific to RPXlite boards 139- board/c2mon Files specific to c2mon boards 140- board/cogent Files specific to Cogent boards 141 (need further configuration) 142 Files specific to CPCIISER4 boards 143- board/cpu86 Files specific to CPU86 boards 144- board/cray/ Files specific to boards manufactured by Cray 145- board/cray/L1 Files specific to L1 boards 146- board/cu824 Files specific to CU824 boards 147- board/ebony Files specific to IBM Ebony board 148- board/eric Files specific to ERIC boards 149- board/esd/ Files specific to boards manufactured by ESD 150- board/esd/adciop Files specific to ADCIOP boards 151- board/esd/ar405 Files specific to AR405 boards 152- board/esd/canbt Files specific to CANBT boards 153- board/esd/cpci405 Files specific to CPCI405 boards 154- board/esd/cpciiser4 Files specific to CPCIISER4 boards 155- board/esd/common Common files for ESD boards 156- board/esd/dasa_sim Files specific to DASA_SIM boards 157- board/esd/du405 Files specific to DU405 boards 158- board/esd/ocrtc Files specific to OCRTC boards 159- board/esd/pci405 Files specific to PCI405 boards 160- board/esteem192e 161 Files specific to ESTEEM192E boards 162- board/etx094 Files specific to ETX_094 boards 163- board/evb64260 164 Files specific to EVB64260 boards 165- board/fads Files specific to FADS boards 166- board/flagadm Files specific to FLAGADM boards 167- board/gen860t Files specific to GEN860T boards 168- board/genietv Files specific to GENIETV boards 169- board/gth Files specific to GTH boards 170- board/hermes Files specific to HERMES boards 171- board/hymod Files specific to HYMOD boards 172- board/icu862 Files specific to ICU862 boards 173- board/ip860 Files specific to IP860 boards 174- board/iphase4539 175 Files specific to Interphase4539 boards 176- board/ivm Files specific to IVMS8/IVML24 boards 177- board/lantec Files specific to LANTEC boards 178- board/lwmon Files specific to LWMON boards 179- board/mbx8xx Files specific to MBX boards 180- board/mpc8260ads 181 Files specific to MMPC8260ADS boards 182- board/mpl/ Files specific to boards manufactured by MPL 183- board/mpl/common Common files for MPL boards 184- board/mpl/pip405 Files specific to PIP405 boards 185- board/mpl/mip405 Files specific to MIP405 boards 186- board/musenki Files specific to MUSEKNI boards 187- board/mvs1 Files specific to MVS1 boards 188- board/nx823 Files specific to NX823 boards 189- board/oxc Files specific to OXC boards 190- board/pcippc2 Files specific to PCIPPC2/PCIPPC6 boards 191- board/pm826 Files specific to PM826 boards 192- board/ppmc8260 193 Files specific to PPMC8260 boards 194- board/rpxsuper 195 Files specific to RPXsuper boards 196- board/rsdproto 197 Files specific to RSDproto boards 198- board/sandpoint 199 Files specific to Sandpoint boards 200- board/sbc8260 Files specific to SBC8260 boards 201- board/sacsng Files specific to SACSng boards 202- board/siemens Files specific to boards manufactured by Siemens AG 203- board/siemens/CCM Files specific to CCM boards 204- board/siemens/IAD210 Files specific to IAD210 boards 205- board/siemens/SCM Files specific to SCM boards 206- board/siemens/pcu_e Files specific to PCU_E boards 207- board/sixnet Files specific to SIXNET boards 208- board/spd8xx Files specific to SPD8xxTS boards 209- board/tqm8260 Files specific to TQM8260 boards 210- board/tqm8xx Files specific to TQM8xxL boards 211- board/w7o Files specific to W7O boards 212- board/walnut405 213 Files specific to Walnut405 boards 214- board/westel/ Files specific to boards manufactured by Westel Wireless 215- board/westel/amx860 Files specific to AMX860 boards 216- board/utx8245 Files specific to UTX8245 boards 217 218Software Configuration: 219======================= 220 221Configuration is usually done using C preprocessor defines; the 222rationale behind that is to avoid dead code whenever possible. 223 224There are two classes of configuration variables: 225 226* Configuration _OPTIONS_: 227 These are selectable by the user and have names beginning with 228 "CONFIG_". 229 230* Configuration _SETTINGS_: 231 These depend on the hardware etc. and should not be meddled with if 232 you don't know what you're doing; they have names beginning with 233 "CFG_". 234 235Later we will add a configuration tool - probably similar to or even 236identical to what's used for the Linux kernel. Right now, we have to 237do the configuration by hand, which means creating some symbolic 238links and editing some configuration files. We use the TQM8xxL boards 239as an example here. 240 241 242Selection of Processor Architecture and Board Type: 243--------------------------------------------------- 244 245For all supported boards there are ready-to-use default 246configurations available; just type "make <board_name>_config". 247 248Example: For a TQM823L module type: 249 250 cd u-boot 251 make TQM823L_config 252 253For the Cogent platform, you need to specify the cpu type as well; 254e.g. "make cogent_mpc8xx_config". And also configure the cogent 255directory according to the instructions in cogent/README. 256 257 258Configuration Options: 259---------------------- 260 261Configuration depends on the combination of board and CPU type; all 262such information is kept in a configuration file 263"include/configs/<board_name>.h". 264 265Example: For a TQM823L module, all configuration settings are in 266"include/configs/TQM823L.h". 267 268 269Many of the options are named exactly as the corresponding Linux 270kernel configuration options. The intention is to make it easier to 271build a config tool - later. 272 273 274The following options need to be configured: 275 276- CPU Type: Define exactly one of 277 278 PowerPC based CPUs: 279 ------------------- 280 CONFIG_MPC823, CONFIG_MPC850, CONFIG_MPC855, CONFIG_MPC860 281 or CONFIG_MPC824X, CONFIG_MPC8260 282 or CONFIG_IOP480 283 or CONFIG_405GP 284 or CONFIG_440 285 or CONFIG_MPC74xx 286 287 ARM based CPUs: 288 --------------- 289 CONFIG_SA1110 290 CONFIG_ARM7 291 CONFIG_PXA250 292 293 294- Board Type: Define exactly one of 295 296 PowerPC based boards: 297 --------------------- 298 299 CONFIG_ADCIOP, CONFIG_ICU862 CONFIG_RPXsuper, 300 CONFIG_ADS860, CONFIG_IP860, CONFIG_SM850, 301 CONFIG_AMX860, CONFIG_IPHASE4539, CONFIG_SPD823TS, 302 CONFIG_AR405, CONFIG_IVML24, CONFIG_SXNI855T, 303 CONFIG_BAB7xx, CONFIG_IVML24_128, CONFIG_Sandpoint8240, 304 CONFIG_CANBT, CONFIG_IVML24_256, CONFIG_Sandpoint8245, 305 CONFIG_CCM, CONFIG_IVMS8, CONFIG_TQM823L, 306 CONFIG_CPCI405, CONFIG_IVMS8_128, CONFIG_TQM850L, 307 CONFIG_CPCI4052, CONFIG_IVMS8_256, CONFIG_TQM855L, 308 CONFIG_CPCIISER4, CONFIG_LANTEC, CONFIG_TQM860L, 309 CONFIG_CPU86, CONFIG_MBX, CONFIG_TQM8260, 310 CONFIG_CRAYL1, CONFIG_MBX860T, CONFIG_TTTech, 311 CONFIG_CU824, CONFIG_MHPC, CONFIG_UTX8245, 312 CONFIG_DASA_SIM, CONFIG_MIP405, CONFIG_W7OLMC, 313 CONFIG_DU405, CONFIG_MOUSSE, CONFIG_W7OLMG, 314 CONFIG_ELPPC, CONFIG_MPC8260ADS, CONFIG_WALNUT405, 315 CONFIG_ERIC, CONFIG_MUSENKI, CONFIG_ZUMA, 316 CONFIG_ESTEEM192E, CONFIG_MVS1, CONFIG_c2mon, 317 CONFIG_ETX094, CONFIG_NX823, CONFIG_cogent_mpc8260, 318 CONFIG_EVB64260, CONFIG_OCRTC, CONFIG_cogent_mpc8xx, 319 CONFIG_FADS823, CONFIG_ORSG, CONFIG_ep8260, 320 CONFIG_FADS850SAR, CONFIG_OXC, CONFIG_gw8260, 321 CONFIG_FADS860T, CONFIG_PCI405, CONFIG_hermes, 322 CONFIG_FLAGADM, CONFIG_PCIPPC2, CONFIG_hymod, 323 CONFIG_FPS850L, CONFIG_PCIPPC6, CONFIG_lwmon, 324 CONFIG_GEN860T, CONFIG_PIP405, CONFIG_pcu_e, 325 CONFIG_GENIETV, CONFIG_PM826, CONFIG_ppmc8260, 326 CONFIG_GTH, CONFIG_RPXClassic, CONFIG_rsdproto, 327 CONFIG_IAD210, CONFIG_RPXlite, CONFIG_sbc8260, 328 CONFIG_EBONY, CONFIG_sacsng, CONFIG_FPS860L 329 330 ARM based boards: 331 ----------------- 332 333 CONFIG_HHP_CRADLE, CONFIG_DNP1110, CONFIG_EP7312, 334 CONFIG_IMPA7, CONFIG_LART, CONFIG_LUBBOCK, 335 CONFIG_SHANNON, CONFIG_SMDK2400, CONFIG_SMDK2410, 336 CONFIG_TRAB 337 338 339- CPU Module Type: (if CONFIG_COGENT is defined) 340 Define exactly one of 341 CONFIG_CMA286_60_OLD 342--- FIXME --- not tested yet: 343 CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P, 344 CONFIG_CMA287_23, CONFIG_CMA287_50 345 346- Motherboard Type: (if CONFIG_COGENT is defined) 347 Define exactly one of 348 CONFIG_CMA101, CONFIG_CMA102 349 350- Motherboard I/O Modules: (if CONFIG_COGENT is defined) 351 Define one or more of 352 CONFIG_CMA302 353 354- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined) 355 Define one or more of 356 CONFIG_LCD_HEARTBEAT - update a character position on 357 the lcd display every second with 358 a "rotator" |\-/|\-/ 359 360- MPC824X Family Member (if CONFIG_MPC824X is defined) 361 Define exactly one of 362 CONFIG_MPC8240, CONFIG_MPC8245 363 364- 8xx CPU Options: (if using an 8xx cpu) 365 Define one or more of 366 CONFIG_8xx_GCLK_FREQ - if get_gclk_freq() can not work e.g. 367 no 32KHz reference PIT/RTC clock 368 369- Clock Interface: 370 CONFIG_CLOCKS_IN_MHZ 371 372 U-Boot stores all clock information in Hz 373 internally. For binary compatibility with older Linux 374 kernels (which expect the clocks passed in the 375 bd_info data to be in MHz) the environment variable 376 "clocks_in_mhz" can be defined so that U-Boot 377 converts clock data to MHZ before passing it to the 378 Linux kernel. 379 380 When CONFIG_CLOCKS_IN_MHZ is defined, a definition of 381 "clocks_in_mhz=1" is automatically included in the 382 default environment. 383 384- Console Interface: 385 Depending on board, define exactly one serial port 386 (like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2, 387 CONFIG_8xx_CONS_SCC1, ...), or switch off the serial 388 console by defining CONFIG_8xx_CONS_NONE 389 390 Note: if CONFIG_8xx_CONS_NONE is defined, the serial 391 port routines must be defined elsewhere 392 (i.e. serial_init(), serial_getc(), ...) 393 394 CONFIG_CFB_CONSOLE 395 Enables console device for a color framebuffer. Needs following 396 defines (cf. smiLynxEM, i8042, board/eltec/bab7xx) 397 VIDEO_FB_LITTLE_ENDIAN graphic memory organisation 398 (default big endian) 399 VIDEO_HW_RECTFILL graphic chip supports 400 rectangle fill 401 (cf. smiLynxEM) 402 VIDEO_HW_BITBLT graphic chip supports 403 bit-blit (cf. smiLynxEM) 404 VIDEO_VISIBLE_COLS visible pixel columns 405 (cols=pitch) 406 VIDEO_VISIBLE_ROWS visible pixel rows 407 VIDEO_PIXEL_SIZE bytes per pixel 408 VIDEO_DATA_FORMAT graphic data format 409 (0-5, cf. cfb_console.c) 410 VIDEO_FB_ADRS framebuffer address 411 VIDEO_KBD_INIT_FCT keyboard int fct 412 (i.e. i8042_kbd_init()) 413 VIDEO_TSTC_FCT test char fct 414 (i.e. i8042_tstc) 415 VIDEO_GETC_FCT get char fct 416 (i.e. i8042_getc) 417 CONFIG_CONSOLE_CURSOR cursor drawing on/off 418 (requires blink timer 419 cf. i8042.c) 420 CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c) 421 CONFIG_CONSOLE_TIME display time/date info in 422 upper right corner 423 (requires CFG_CMD_DATE) 424 CONFIG_VIDEO_LOGO display Linux logo in 425 upper left corner 426 CONFIG_CONSOLE_EXTRA_INFO 427 addional board info beside 428 the logo 429 430 When CONFIG_CFB_CONSOLE is defined, video console is 431 default i/o. Serial console can be forced with 432 environment 'console=serial'. 433 434- Console Baudrate: 435 CONFIG_BAUDRATE - in bps 436 Select one of the baudrates listed in 437 CFG_BAUDRATE_TABLE, see below. 438 439- Interrupt driven serial port input: 440 CONFIG_SERIAL_SOFTWARE_FIFO 441 442 PPC405GP only. 443 Use an interrupt handler for receiving data on the 444 serial port. It also enables using hardware handshake 445 (RTS/CTS) and UART's built-in FIFO. Set the number of 446 bytes the interrupt driven input buffer should have. 447 448 Set to 0 to disable this feature (this is the default). 449 This will also disable hardware handshake. 450 451- Boot Delay: CONFIG_BOOTDELAY - in seconds 452 Delay before automatically booting the default image; 453 set to -1 to disable autoboot. 454 455 See doc/README.autoboot for these options that 456 work with CONFIG_BOOTDELAY. None are required. 457 CONFIG_BOOT_RETRY_TIME 458 CONFIG_BOOT_RETRY_MIN 459 CONFIG_AUTOBOOT_KEYED 460 CONFIG_AUTOBOOT_PROMPT 461 CONFIG_AUTOBOOT_DELAY_STR 462 CONFIG_AUTOBOOT_STOP_STR 463 CONFIG_AUTOBOOT_DELAY_STR2 464 CONFIG_AUTOBOOT_STOP_STR2 465 CONFIG_ZERO_BOOTDELAY_CHECK 466 CONFIG_RESET_TO_RETRY 467 468- Autoboot Command: 469 CONFIG_BOOTCOMMAND 470 Only needed when CONFIG_BOOTDELAY is enabled; 471 define a command string that is automatically executed 472 when no character is read on the console interface 473 within "Boot Delay" after reset. 474 475 CONFIG_BOOTARGS 476 This can be used to pass arguments to the bootm 477 command. The value of CONFIG_BOOTARGS goes into the 478 environment value "bootargs". 479 480 CONFIG_RAMBOOT and CONFIG_NFSBOOT 481 The value of these goes into the environment as 482 "ramboot" and "nfsboot" respectively, and can be used 483 as a convenience, when switching between booting from 484 ram and nfs. 485 486- Pre-Boot Commands: 487 CONFIG_PREBOOT 488 489 When this option is #defined, the existence of the 490 environment variable "preboot" will be checked 491 immediately before starting the CONFIG_BOOTDELAY 492 countdown and/or running the auto-boot command resp. 493 entering interactive mode. 494 495 This feature is especially useful when "preboot" is 496 automatically generated or modified. For an example 497 see the LWMON board specific code: here "preboot" is 498 modified when the user holds down a certain 499 combination of keys on the (special) keyboard when 500 booting the systems 501 502- Serial Download Echo Mode: 503 CONFIG_LOADS_ECHO 504 If defined to 1, all characters received during a 505 serial download (using the "loads" command) are 506 echoed back. This might be needed by some terminal 507 emulations (like "cu"), but may as well just take 508 time on others. This setting #define's the initial 509 value of the "loads_echo" environment variable. 510 511- Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined) 512 CONFIG_KGDB_BAUDRATE 513 Select one of the baudrates listed in 514 CFG_BAUDRATE_TABLE, see below. 515 516- Monitor Functions: 517 CONFIG_COMMANDS 518 Most monitor functions can be selected (or 519 de-selected) by adjusting the definition of 520 CONFIG_COMMANDS; to select individual functions, 521 #define CONFIG_COMMANDS by "OR"ing any of the 522 following values: 523 524 #define enables commands: 525 ------------------------- 526 CFG_CMD_ASKENV * ask for env variable 527 CFG_CMD_BDI bdinfo 528 CFG_CMD_BEDBUG Include BedBug Debugger 529 CFG_CMD_BOOTD bootd 530 CFG_CMD_CACHE icache, dcache 531 CFG_CMD_CONSOLE coninfo 532 CFG_CMD_DATE * support for RTC, date/time... 533 CFG_CMD_DHCP DHCP support 534 CFG_CMD_ECHO * echo arguments 535 CFG_CMD_EEPROM * EEPROM read/write support 536 CFG_CMD_ELF bootelf, bootvx 537 CFG_CMD_ENV saveenv 538 CFG_CMD_FDC * Floppy Disk Support 539 CFG_CMD_FLASH flinfo, erase, protect 540 CFG_CMD_FPGA FPGA device initialization support 541 CFG_CMD_I2C * I2C serial bus support 542 CFG_CMD_IDE * IDE harddisk support 543 CFG_CMD_IMI iminfo 544 CFG_CMD_IMMAP * IMMR dump support 545 CFG_CMD_IRQ * irqinfo 546 CFG_CMD_KGDB * kgdb 547 CFG_CMD_LOADB loadb 548 CFG_CMD_LOADS loads 549 CFG_CMD_MEMORY md, mm, nm, mw, cp, cmp, crc, base, 550 loop, mtest 551 CFG_CMD_MII MII utility commands 552 CFG_CMD_NET bootp, tftpboot, rarpboot 553 CFG_CMD_PCI * pciinfo 554 CFG_CMD_PCMCIA * PCMCIA support 555 CFG_CMD_REGINFO * Register dump 556 CFG_CMD_RUN run command in env variable 557 CFG_CMD_SCSI * SCSI Support 558 CFG_CMD_SETGETDCR Support for DCR Register access (4xx only) 559 CFG_CMD_SPI * SPI serial bus support 560 CFG_CMD_USB * USB support 561 CFG_CMD_BSP * Board SPecific functions 562 ----------------------------------------------- 563 CFG_CMD_ALL all 564 565 CFG_CMD_DFL Default configuration; at the moment 566 this is includes all commands, except 567 the ones marked with "*" in the list 568 above. 569 570 If you don't define CONFIG_COMMANDS it defaults to 571 CFG_CMD_DFL in include/cmd_confdefs.h. A board can 572 override the default settings in the respective 573 include file. 574 575 EXAMPLE: If you want all functions except of network 576 support you can write: 577 578 #define CONFIG_COMMANDS (CFG_CMD_ALL & ~CFG_CMD_NET) 579 580 581 Note: Don't enable the "icache" and "dcache" commands 582 (configuration option CFG_CMD_CACHE) unless you know 583 what you (and your U-Boot users) are doing. Data 584 cache cannot be enabled on systems like the 8xx or 585 8260 (where accesses to the IMMR region must be 586 uncached), and it cannot be disabled on all other 587 systems where we (mis-) use the data cache to hold an 588 initial stack and some data. 589 590 591 XXX - this list needs to get updated! 592 593- Watchdog: 594 CONFIG_WATCHDOG 595 If this variable is defined, it enables watchdog 596 support. There must support in the platform specific 597 code for a watchdog. For the 8xx and 8260 CPUs, the 598 SIU Watchdog feature is enabled in the SYPCR 599 register. 600 601- Real-Time Clock: 602 603 When CFG_CMD_DATE is selected, the type of the RTC 604 has to be selected, too. Define exactly one of the 605 following options: 606 607 CONFIG_RTC_MPC8xx - use internal RTC of MPC8xx 608 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC 609 CONFIG_RTC_MC146818 - use MC146818 RTC 610 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC 611 612- Timestamp Support: 613 614 When CONFIG_TIMESTAMP is selected, the timestamp 615 (date and time) of an image is printed by image 616 commands like bootm or iminfo. This option is 617 automatically enabled when you select CFG_CMD_DATE . 618 619- Partition Support: 620 CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION 621 and/or CONFIG_ISO_PARTITION 622 623 If IDE or SCSI support is enabled (CFG_CMD_IDE or 624 CFG_CMD_SCSI) you must configure support for at least 625 one partition type as well. 626 627- IDE Reset method: 628 CONFIG_IDE_RESET_ROUTINE 629 630 Set this to define that instead of a reset Pin, the 631 routine ide_set_reset(int idereset) will be used. 632 633- ATAPI Support: 634 CONFIG_ATAPI 635 636 Set this to enable ATAPI support. 637 638- SCSI Support: 639 At the moment only there is only support for the 640 SYM53C8XX SCSI controller; define 641 CONFIG_SCSI_SYM53C8XX to enable it. 642 643 CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and 644 CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID * 645 CFG_SCSI_MAX_LUN] can be adjusted to define the 646 maximum numbers of LUNs, SCSI ID's and target 647 devices. 648 CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz) 649 650- NETWORK Support (PCI): 651 CONFIG_EEPRO100 652 Support for Intel 82557/82559/82559ER chips. 653 Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom 654 write routine for first time initialisation. 655 656 CONFIG_TULIP 657 Support for Digital 2114x chips. 658 Optional CONFIG_TULIP_SELECT_MEDIA for board specific 659 modem chip initialisation (KS8761/QS6611). 660 661 CONFIG_NATSEMI 662 Support for National dp83815 chips. 663 664 CONFIG_NS8382X 665 Support for National dp8382[01] gigabit chips. 666 667- USB Support: 668 At the moment only the UHCI host controller is 669 supported (PIP405, MIP405); define 670 CONFIG_USB_UHCI to enable it. 671 define CONFIG_USB_KEYBOARD to enable the USB Keyboard 672 end define CONFIG_USB_STORAGE to enable the USB 673 storage devices. 674 Note: 675 Supported are USB Keyboards and USB Floppy drives 676 (TEAC FD-05PUB). 677 678- Keyboard Support: 679 CONFIG_ISA_KEYBOARD 680 681 Define this to enable standard (PC-Style) keyboard 682 support 683 684 CONFIG_I8042_KBD 685 Standard PC keyboard driver with US (is default) and 686 GERMAN key layout (switch via environment 'keymap=de') support. 687 Export function i8042_kbd_init, i8042_tstc and i8042_getc 688 for cfb_console. Supports cursor blinking. 689 690- Video support: 691 CONFIG_VIDEO 692 693 Define this to enable video support (for output to 694 video). 695 696 CONFIG_VIDEO_CT69000 697 698 Enable Chips & Technologies 69000 Video chip 699 700 CONFIG_VIDEO_SMI_LYNXEM 701 Enable Silicon Motion SMI 712/710/810 Video chip 702 Videomode are selected via environment 'videomode' with 703 standard LiLo mode numbers. 704 Following modes are supported (* is default): 705 706 800x600 1024x768 1280x1024 707 256 (8bit) 303* 305 307 708 65536 (16bit) 314 317 31a 709 16,7 Mill (24bit) 315 318 31b 710 (i.e. setenv videomode 317; saveenv; reset;) 711 712- LCD Support: CONFIG_LCD 713 714 Define this to enable LCD support (for output to LCD 715 display); also select one of the supported displays 716 by defining one of these: 717 718 CONFIG_NEC_NL6648AC33: 719 720 NEC NL6648AC33-18. Active, color, single scan. 721 722 CONFIG_NEC_NL6648BC20 723 724 NEC NL6648BC20-08. 6.5", 640x480. 725 Active, color, single scan. 726 727 CONFIG_SHARP_16x9 728 729 Sharp 320x240. Active, color, single scan. 730 It isn't 16x9, and I am not sure what it is. 731 732 CONFIG_SHARP_LQ64D341 733 734 Sharp LQ64D341 display, 640x480. 735 Active, color, single scan. 736 737 CONFIG_HLD1045 738 739 HLD1045 display, 640x480. 740 Active, color, single scan. 741 742 CONFIG_OPTREX_BW 743 744 Optrex CBL50840-2 NF-FW 99 22 M5 745 or 746 Hitachi LMG6912RPFC-00T 747 or 748 Hitachi SP14Q002 749 750 320x240. Black & white. 751 752 Normally display is black on white background; define 753 CFG_WHITE_ON_BLACK to get it inverted. 754 755- Ethernet address: 756 CONFIG_ETHADDR 757 CONFIG_ETH2ADDR 758 CONFIG_ETH3ADDR 759 760 Define a default value for ethernet address to use 761 for the respective ethernet interface, in case this 762 is not determined automatically. 763 764- IP address: 765 CONFIG_IPADDR 766 767 Define a default value for the IP address to use for 768 the default ethernet interface, in case this is not 769 determined through e.g. bootp. 770 771- Server IP address: 772 CONFIG_SERVERIP 773 774 Defines a default value for theIP address of a TFTP 775 server to contact when using the "tftboot" command. 776 777- BOOTP Recovery Mode: 778 CONFIG_BOOTP_RANDOM_DELAY 779 780 If you have many targets in a network that try to 781 boot using BOOTP, you may want to avoid that all 782 systems send out BOOTP requests at precisely the same 783 moment (which would happen for instance at recovery 784 from a power failure, when all systems will try to 785 boot, thus flooding the BOOTP server. Defining 786 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be 787 inserted before sending out BOOTP requests. The 788 following delays are insterted then: 789 790 1st BOOTP request: delay 0 ... 1 sec 791 2nd BOOTP request: delay 0 ... 2 sec 792 3rd BOOTP request: delay 0 ... 4 sec 793 4th and following 794 BOOTP requests: delay 0 ... 8 sec 795 796- Status LED: CONFIG_STATUS_LED 797 798 Several configurations allow to display the current 799 status using a LED. For instance, the LED will blink 800 fast while running U-Boot code, stop blinking as 801 soon as a reply to a BOOTP request was received, and 802 start blinking slow once the Linux kernel is running 803 (supported by a status LED driver in the Linux 804 kernel). Defining CONFIG_STATUS_LED enables this 805 feature in U-Boot. 806 807- CAN Support: CONFIG_CAN_DRIVER 808 809 Defining CONFIG_CAN_DRIVER enables CAN driver support 810 on those systems that support this (optional) 811 feature, like the TQM8xxL modules. 812 813- I2C Support: CONFIG_HARD_I2C | CONFIG_SOFT_I2C 814 815 Enables I2C serial bus commands. If this is selected, 816 either CONFIG_HARD_I2C or CONFIG_SOFT_I2C must be defined 817 to include the appropriate I2C driver. 818 819 See also: common/cmd_i2c.c for a description of the 820 command line interface. 821 822 823 CONFIG_HARD_I2C 824 825 Selects the CPM hardware driver for I2C. 826 827 CONFIG_SOFT_I2C 828 829 Use software (aka bit-banging) driver instead of CPM 830 or similar hardware support for I2C. This is configured 831 via the following defines. 832 833 I2C_INIT 834 835 (Optional). Any commands necessary to enable I2C 836 controller or configure ports. 837 838 I2C_PORT 839 840 (Only for MPC8260 CPU). The I/O port to use (the code 841 assumes both bits are on the same port). Valid values 842 are 0..3 for ports A..D. 843 844 I2C_ACTIVE 845 846 The code necessary to make the I2C data line active 847 (driven). If the data line is open collector, this 848 define can be null. 849 850 I2C_TRISTATE 851 852 The code necessary to make the I2C data line tri-stated 853 (inactive). If the data line is open collector, this 854 define can be null. 855 856 I2C_READ 857 858 Code that returns TRUE if the I2C data line is high, 859 FALSE if it is low. 860 861 I2C_SDA(bit) 862 863 If <bit> is TRUE, sets the I2C data line high. If it 864 is FALSE, it clears it (low). 865 866 I2C_SCL(bit) 867 868 If <bit> is TRUE, sets the I2C clock line high. If it 869 is FALSE, it clears it (low). 870 871 I2C_DELAY 872 873 This delay is invoked four times per clock cycle so this 874 controls the rate of data transfer. The data rate thus 875 is 1 / (I2C_DELAY * 4). 876 877- SPI Support: CONFIG_SPI 878 879 Enables SPI driver (so far only tested with 880 SPI EEPROM, also an instance works with Crystal A/D and 881 D/As on the SACSng board) 882 883 CONFIG_SPI_X 884 885 Enables extended (16-bit) SPI EEPROM addressing. 886 (symmetrical to CONFIG_I2C_X) 887 888 CONFIG_SOFT_SPI 889 890 Enables a software (bit-bang) SPI driver rather than 891 using hardware support. This is a general purpose 892 driver that only requires three general I/O port pins 893 (two outputs, one input) to function. If this is 894 defined, the board configuration must define several 895 SPI configuration items (port pins to use, etc). For 896 an example, see include/configs/sacsng.h. 897 898- FPGA Support: CONFIG_FPGA_COUNT 899 900 Specify the number of FPGA devices to support. 901 902 CONFIG_FPGA 903 904 Used to specify the types of FPGA devices. For 905 example, 906 #define CONFIG_FPGA CFG_XILINX_VIRTEX2 907 908 CFG_FPGA_PROG_FEEDBACK 909 910 Enable printing of hash marks during FPGA 911 configuration. 912 913 CFG_FPGA_CHECK_BUSY 914 915 Enable checks on FPGA configuration interface busy 916 status by the configuration function. This option 917 will require a board or device specific function to 918 be written. 919 920 CONFIG_FPGA_DELAY 921 922 If defined, a function that provides delays in the 923 FPGA configuration driver. 924 925 CFG_FPGA_CHECK_CTRLC 926 927 Allow Control-C to interrupt FPGA configuration 928 929 CFG_FPGA_CHECK_ERROR 930 931 Check for configuration errors during FPGA bitfile 932 loading. For example, abort during Virtex II 933 configuration if the INIT_B line goes low (which 934 indicated a CRC error). 935 936 CFG_FPGA_WAIT_INIT 937 938 Maximum time to wait for the INIT_B line to deassert 939 after PROB_B has been deasserted during a Virtex II 940 FPGA configuration sequence. The default time is 500 mS. 941 942 CFG_FPGA_WAIT_BUSY 943 944 Maximum time to wait for BUSY to deassert during 945 Virtex II FPGA configuration. The default is 5 mS. 946 947 CFG_FPGA_WAIT_CONFIG 948 949 Time to wait after FPGA configuration. The default is 950 200 mS. 951 952- FPGA Support: CONFIG_FPGA_COUNT 953 954 Specify the number of FPGA devices to support. 955 956 CONFIG_FPGA 957 958 Used to specify the types of FPGA devices. For example, 959 #define CONFIG_FPGA CFG_XILINX_VIRTEX2 960 961 CFG_FPGA_PROG_FEEDBACK 962 963 Enable printing of hash marks during FPGA configuration. 964 965 CFG_FPGA_CHECK_BUSY 966 967 Enable checks on FPGA configuration interface busy 968 status by the configuration function. This option 969 will require a board or device specific function to 970 be written. 971 972 CONFIG_FPGA_DELAY 973 974 If defined, a function that provides delays in the FPGA 975 configuration driver. 976 977 CFG_FPGA_CHECK_CTRLC 978 Allow Control-C to interrupt FPGA configuration 979 980 CFG_FPGA_CHECK_ERROR 981 982 Check for configuration errors during FPGA bitfile 983 loading. For example, abort during Virtex II 984 configuration if the INIT_B line goes low (which 985 indicated a CRC error). 986 987 CFG_FPGA_WAIT_INIT 988 989 Maximum time to wait for the INIT_B line to deassert 990 after PROB_B has been deasserted during a Virtex II 991 FPGA configuration sequence. The default time is 500 992 mS. 993 994 CFG_FPGA_WAIT_BUSY 995 996 Maximum time to wait for BUSY to deassert during 997 Virtex II FPGA configuration. The default is 5 mS. 998 999 CFG_FPGA_WAIT_CONFIG 1000 1001 Time to wait after FPGA configuration. The default is 1002 200 mS. 1003 1004- Configuration Management: 1005 CONFIG_IDENT_STRING 1006 1007 If defined, this string will be added to the U-Boot 1008 version information (U_BOOT_VERSION) 1009 1010- Vendor Parameter Protection: 1011 1012 U-Boot considers the values of the environment 1013 variables "serial#" (Board Serial Number) and 1014 "ethaddr" (Ethernet Address) to bb parameters that 1015 are set once by the board vendor / manufacturer, and 1016 protects these variables from casual modification by 1017 the user. Once set, these variables are read-only, 1018 and write or delete attempts are rejected. You can 1019 change this behviour: 1020 1021 If CONFIG_ENV_OVERWRITE is #defined in your config 1022 file, the write protection for vendor parameters is 1023 completely disabled. Anybody can change or delte 1024 these parameters. 1025 1026 Alternatively, if you #define _both_ CONFIG_ETHADDR 1027 _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default 1028 ethernet address is installed in the environment, 1029 which can be changed exactly ONCE by the user. [The 1030 serial# is unaffected by this, i. e. it remains 1031 read-only.] 1032 1033- Protected RAM: 1034 CONFIG_PRAM 1035 1036 Define this variable to enable the reservation of 1037 "protected RAM", i. e. RAM which is not overwritten 1038 by U-Boot. Define CONFIG_PRAM to hold the number of 1039 kB you want to reserve for pRAM. You can overwrite 1040 this default value by defining an environment 1041 variable "pram" to the number of kB you want to 1042 reserve. Note that the board info structure will 1043 still show the full amount of RAM. If pRAM is 1044 reserved, a new environment variable "mem" will 1045 automatically be defined to hold the amount of 1046 remaining RAM in a form that can be passed as boot 1047 argument to Linux, for instance like that: 1048 1049 setenv bootargs ... mem=\$(mem) 1050 saveenv 1051 1052 This way you can tell Linux not to use this memory, 1053 either, which results in a memory region that will 1054 not be affected by reboots. 1055 1056 *WARNING* If your board configuration uses automatic 1057 detection of the RAM size, you must make sure that 1058 this memory test is non-destructive. So far, the 1059 following board configurations are known to be 1060 "pRAM-clean": 1061 1062 ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL, 1063 HERMES, IP860, RPXlite, LWMON, LANTEC, 1064 PCU_E, FLAGADM, TQM8260 1065 1066- Error Recovery: 1067 CONFIG_PANIC_HANG 1068 1069 Define this variable to stop the system in case of a 1070 fatal error, so that you have to reset it manually. 1071 This is probably NOT a good idea for an embedded 1072 system where you want to system to reboot 1073 automatically as fast as possible, but it may be 1074 useful during development since you can try to debug 1075 the conditions that lead to the situation. 1076 1077 CONFIG_NET_RETRY_COUNT 1078 1079 This variable defines the number of retries for 1080 network operations like ARP, RARP, TFTP, or BOOTP 1081 before giving up the operation. If not defined, a 1082 default value of 5 is used. 1083 1084- Command Interpreter: 1085 CFG_HUSH_PARSER 1086 1087 Define this variable to enable the "hush" shell (from 1088 Busybox) as command line interpreter, thus enabling 1089 powerful command line syntax like 1090 if...then...else...fi conditionals or `&&' and '||' 1091 constructs ("shell scripts"). 1092 1093 If undefined, you get the old, much simpler behaviour 1094 with a somewhat smaller memory footprint. 1095 1096 1097 CFG_PROMPT_HUSH_PS2 1098 1099 This defines the secondary prompt string, which is 1100 printed when the command interpreter needs more input 1101 to complete a command. Usually "> ". 1102 1103 Note: 1104 1105 In the current implementation, the local variables 1106 space and global environment variables space are 1107 separated. Local variables are those you define by 1108 simply typing like `name=value'. To access a local 1109 variable later on, you have write `$name' or 1110 `${name}'; variable directly by typing say `$name' at 1111 the command prompt. 1112 1113 Global environment variables are those you use 1114 setenv/printenv to work with. To run a command stored 1115 in such a variable, you need to use the run command, 1116 and you must not use the '$' sign to access them. 1117 1118 To store commands and special characters in a 1119 variable, please use double quotation marks 1120 surrounding the whole text of the variable, instead 1121 of the backslashes before semicolons and special 1122 symbols. 1123 1124- Default Environment 1125 CONFIG_EXTRA_ENV_SETTINGS 1126 1127 Define this to contain any number of null terminated 1128 strings (variable = value pairs) that will be part of 1129 the default enviroment compiled into the boot image. 1130 For example, place something like this in your 1131 board's config file: 1132 1133 #define CONFIG_EXTRA_ENV_SETTINGS \ 1134 "myvar1=value1\0" \ 1135 "myvar2=value2\0" 1136 1137 Warning: This method is based on knowledge about the 1138 internal format how the environment is stored by the 1139 U-Boot code. This is NOT an official, expoerted 1140 interface! Although it is unlikely that this format 1141 will change soon, there is no guarantee either. 1142 You better know what you are doing here. 1143 1144 Note: overly (ab)use of the default environment is 1145 discouraged. Make sure to check other ways to preset 1146 the environment like the autoscript function or the 1147 boot command first. 1148 1149- Show boot progress 1150 CONFIG_SHOW_BOOT_PROGRESS 1151 1152 Defining this option allows to add some board- 1153 specific code (calling a user-provided function 1154 "show_boot_progress(int)") that enables you to show 1155 the system's boot progress on some display (for 1156 example, some LED's) on your board. At the moment, 1157 the following checkpoints are implemented: 1158 1159 Arg Where When 1160 1 common/cmd_bootm.c before attempting to boot an image 1161 -1 common/cmd_bootm.c Image header has bad magic number 1162 2 common/cmd_bootm.c Image header has correct magic number 1163 -2 common/cmd_bootm.c Image header has bad checksum 1164 3 common/cmd_bootm.c Image header has correct checksum 1165 -3 common/cmd_bootm.c Image data has bad checksum 1166 4 common/cmd_bootm.c Image data has correct checksum 1167 -4 common/cmd_bootm.c Image is for unsupported architecture 1168 5 common/cmd_bootm.c Architecture check OK 1169 -5 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone) 1170 6 common/cmd_bootm.c Image Type check OK 1171 -6 common/cmd_bootm.c gunzip uncompression error 1172 -7 common/cmd_bootm.c Unimplemented compression type 1173 7 common/cmd_bootm.c Uncompression OK 1174 -8 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone) 1175 8 common/cmd_bootm.c Image Type check OK 1176 -9 common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX) 1177 9 common/cmd_bootm.c Start initial ramdisk verification 1178 -10 common/cmd_bootm.c Ramdisk header has bad magic number 1179 -11 common/cmd_bootm.c Ramdisk header has bad checksum 1180 10 common/cmd_bootm.c Ramdisk header is OK 1181 -12 common/cmd_bootm.c Ramdisk data has bad checksum 1182 11 common/cmd_bootm.c Ramdisk data has correct checksum 1183 12 common/cmd_bootm.c Ramdisk verification complete, start loading 1184 -13 common/cmd_bootm.c Wrong Image Type (not PPC Linux Ramdisk) 1185 13 common/cmd_bootm.c Start multifile image verification 1186 14 common/cmd_bootm.c No initial ramdisk, no multifile, continue. 1187 15 common/cmd_bootm.c All preparation done, transferring control to OS 1188 1189 -1 common/cmd_doc.c Bad usage of "doc" command 1190 -1 common/cmd_doc.c No boot device 1191 -1 common/cmd_doc.c Unknown Chip ID on boot device 1192 -1 common/cmd_doc.c Read Error on boot device 1193 -1 common/cmd_doc.c Image header has bad magic number 1194 1195 -1 common/cmd_ide.c Bad usage of "ide" command 1196 -1 common/cmd_ide.c No boot device 1197 -1 common/cmd_ide.c Unknown boot device 1198 -1 common/cmd_ide.c Unknown partition table 1199 -1 common/cmd_ide.c Invalid partition type 1200 -1 common/cmd_ide.c Read Error on boot device 1201 -1 common/cmd_ide.c Image header has bad magic number 1202 1203 -1 common/cmd_nvedit.c Environment not changable, but has bad CRC 1204 1205 1206Modem Support: 1207-------------- 1208 1209[so far only for SMDK2400 board] 1210 1211- Modem support endable: 1212 CONFIG_MODEM_SUPPORT 1213 1214- RTS/CTS Flow control enable: 1215 CONFIG_HWFLOW 1216 1217- Modem debug support: 1218 CONFIG_MODEM_SUPPORT_DEBUG 1219 1220 Enables debugging stuff (char screen[1024], dbg()) 1221 for modem support. Useful only with BDI2000. 1222 1223- General: 1224 1225 In the target system modem support is enabled when a 1226 specific key (key combination) is pressed during 1227 power-on. Otherwise U-Boot will boot normally 1228 (autoboot). The key_pressed() fuction is called from 1229 board_init(). Currently key_pressed() is a dummy 1230 function, returning 1 and thus enabling modem 1231 initialization. 1232 1233 If there are no modem init strings in the 1234 environment, U-Boot proceed to autoboot; the 1235 previous output (banner, info printfs) will be 1236 supressed, though. 1237 1238 See also: doc/README.Modem 1239 1240 1241 1242 1243Configuration Settings: 1244----------------------- 1245 1246- CFG_LONGHELP: Defined when you want long help messages included; 1247 undefine this when you're short of memory. 1248 1249- CFG_PROMPT: This is what U-Boot prints on the console to 1250 prompt for user input. 1251 1252- CFG_CBSIZE: Buffer size for input from the Console 1253 1254- CFG_PBSIZE: Buffer size for Console output 1255 1256- CFG_MAXARGS: max. Number of arguments accepted for monitor commands 1257 1258- CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to 1259 the application (usually a Linux kernel) when it is 1260 booted 1261 1262- CFG_BAUDRATE_TABLE: 1263 List of legal baudrate settings for this board. 1264 1265- CFG_CONSOLE_INFO_QUIET 1266 Suppress display of console information at boot. 1267 1268- CFG_CONSOLE_IS_IN_ENV 1269 If the board specific function 1270 extern int overwrite_console (void); 1271 returns 1, the stdin, stderr and stdout are switched to the 1272 serial port, else the settings in the environment are used. 1273 1274- CFG_CONSOLE_OVERWRITE_ROUTINE 1275 Enable the call to overwrite_console(). 1276 1277- CFG_CONSOLE_ENV_OVERWRITE 1278 Enable overwrite of previous console environment settings. 1279 1280- CFG_MEMTEST_START, CFG_MEMTEST_END: 1281 Begin and End addresses of the area used by the 1282 simple memory test. 1283 1284- CFG_ALT_MEMTEST: 1285 Enable an alternate, more extensive memory test. 1286 1287- CFG_TFTP_LOADADDR: 1288 Default load address for network file downloads 1289 1290- CFG_LOADS_BAUD_CHANGE: 1291 Enable temporary baudrate change while serial download 1292 1293- CFG_SDRAM_BASE: 1294 Physical start address of SDRAM. _Must_ be 0 here. 1295 1296- CFG_MBIO_BASE: 1297 Physical start address of Motherboard I/O (if using a 1298 Cogent motherboard) 1299 1300- CFG_FLASH_BASE: 1301 Physical start address of Flash memory. 1302 1303- CFG_MONITOR_BASE: 1304 Physical start address of boot monitor code (set by 1305 make config files to be same as the text base address 1306 (TEXT_BASE) used when linking) - same as 1307 CFG_FLASH_BASE when booting from flash. 1308 1309- CFG_MONITOR_LEN: 1310 Size of memory reserved for monitor code 1311 1312- CFG_MALLOC_LEN: 1313 Size of DRAM reserved for malloc() use. 1314 1315- CFG_BOOTMAPSZ: 1316 Maximum size of memory mapped by the startup code of 1317 the Linux kernel; all data that must be processed by 1318 the Linux kernel (bd_info, boot arguments, eventually 1319 initrd image) must be put below this limit. 1320 1321- CFG_MAX_FLASH_BANKS: 1322 Max number of Flash memory banks 1323 1324- CFG_MAX_FLASH_SECT: 1325 Max number of sectors on a Flash chip 1326 1327- CFG_FLASH_ERASE_TOUT: 1328 Timeout for Flash erase operations (in ms) 1329 1330- CFG_FLASH_WRITE_TOUT: 1331 Timeout for Flash write operations (in ms) 1332 1333- CFG_DIRECT_FLASH_TFTP: 1334 1335 Enable TFTP transfers directly to flash memory; 1336 without this option such a download has to be 1337 performed in two steps: (1) download to RAM, and (2) 1338 copy from RAM to flash. 1339 1340 The two-step approach is usually more reliable, since 1341 you can check if the download worked before you erase 1342 the flash, but in some situations (when sytem RAM is 1343 too limited to allow for a tempory copy of the 1344 downloaded image) this option may be very useful. 1345 1346- CFG_FLASH_CFI: 1347 Define if the flash driver uses extra elements in the 1348 common flash structure for storing flash geometry 1349 1350The following definitions that deal with the placement and management 1351of environment data (variable area); in general, we support the 1352following configurations: 1353 1354- CFG_ENV_IS_IN_FLASH: 1355 1356 Define this if the environment is in flash memory. 1357 1358 a) The environment occupies one whole flash sector, which is 1359 "embedded" in the text segment with the U-Boot code. This 1360 happens usually with "bottom boot sector" or "top boot 1361 sector" type flash chips, which have several smaller 1362 sectors at the start or the end. For instance, such a 1363 layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In 1364 such a case you would place the environment in one of the 1365 4 kB sectors - with U-Boot code before and after it. With 1366 "top boot sector" type flash chips, you would put the 1367 environment in one of the last sectors, leaving a gap 1368 between U-Boot and the environment. 1369 1370 - CFG_ENV_OFFSET: 1371 1372 Offset of environment data (variable area) to the 1373 beginning of flash memory; for instance, with bottom boot 1374 type flash chips the second sector can be used: the offset 1375 for this sector is given here. 1376 1377 CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE. 1378 1379 - CFG_ENV_ADDR: 1380 1381 This is just another way to specify the start address of 1382 the flash sector containing the environment (instead of 1383 CFG_ENV_OFFSET). 1384 1385 - CFG_ENV_SECT_SIZE: 1386 1387 Size of the sector containing the environment. 1388 1389 1390 b) Sometimes flash chips have few, equal sized, BIG sectors. 1391 In such a case you don't want to spend a whole sector for 1392 the environment. 1393 1394 - CFG_ENV_SIZE: 1395 1396 If you use this in combination with CFG_ENV_IS_IN_FLASH 1397 and CFG_ENV_SECT_SIZE, you can specify to use only a part 1398 of this flash sector for the environment. This saves 1399 memory for the RAM copy of the environment. 1400 1401 It may also save flash memory if you decide to use this 1402 when your environment is "embedded" within U-Boot code, 1403 since then the remainder of the flash sector could be used 1404 for U-Boot code. It should be pointed out that this is 1405 STRONGLY DISCOURAGED from a robustness point of view: 1406 updating the environment in flash makes it always 1407 necessary to erase the WHOLE sector. If something goes 1408 wrong before the contents has been restored from a copy in 1409 RAM, your target system will be dead. 1410 1411 - CFG_ENV_ADDR_REDUND 1412 CFG_ENV_SIZE_REDUND 1413 1414 These settings describe a second storage area used to hold 1415 a redundand copy of the environment data, so that there is 1416 a valid backup copy in case there is a power failur during 1417 a "saveenv" operation. 1418 1419BE CAREFUL! Any changes to the flash layout, and some changes to the 1420source code will make it necessary to adapt <board>/u-boot.lds* 1421accordingly! 1422 1423 1424- CFG_ENV_IS_IN_NVRAM: 1425 1426 Define this if you have some non-volatile memory device 1427 (NVRAM, battery buffered SRAM) which you want to use for the 1428 environment. 1429 1430 - CFG_ENV_ADDR: 1431 - CFG_ENV_SIZE: 1432 1433 These two #defines are used to determin the memory area you 1434 want to use for environment. It is assumed that this memory 1435 can just be read and written to, without any special 1436 provision. 1437 1438BE CAREFUL! The first access to the environment happens quite early 1439in U-Boot initalization (when we try to get the setting of for the 1440console baudrate). You *MUST* have mappend your NVRAM area then, or 1441U-Boot will hang. 1442 1443Please note that even with NVRAM we still use a copy of the 1444environment in RAM: we could work on NVRAM directly, but we want to 1445keep settings there always unmodified except somebody uses "saveenv" 1446to save the current settings. 1447 1448 1449- CFG_ENV_IS_IN_EEPROM: 1450 1451 Use this if you have an EEPROM or similar serial access 1452 device and a driver for it. 1453 1454 - CFG_ENV_OFFSET: 1455 - CFG_ENV_SIZE: 1456 1457 These two #defines specify the offset and size of the 1458 environment area within the total memory of your EEPROM. 1459 1460 - CFG_I2C_EEPROM_ADDR: 1461 If defined, specified the chip address of the EEPROM device. 1462 The default address is zero. 1463 1464 - CFG_EEPROM_PAGE_WRITE_BITS: 1465 If defined, the number of bits used to address bytes in a 1466 single page in the EEPROM device. A 64 byte page, for example 1467 would require six bits. 1468 1469 - CFG_EEPROM_PAGE_WRITE_DELAY_MS: 1470 If defined, the number of milliseconds to delay between 1471 page writes. The default is zero milliseconds. 1472 1473 - CFG_I2C_EEPROM_ADDR_LEN: 1474 The length in bytes of the EEPROM memory array address. Note 1475 that this is NOT the chip address length! 1476 1477 - CFG_EEPROM_SIZE: 1478 The size in bytes of the EEPROM device. 1479 1480 - CFG_I2C_EEPROM_ADDR: 1481 If defined, specified the chip address of the EEPROM device. 1482 The default address is zero. 1483 1484 - CFG_EEPROM_PAGE_WRITE_BITS: 1485 If defined, the number of bits used to address bytes in a 1486 single page in the EEPROM device. A 64 byte page, for example 1487 would require six bits. 1488 1489 - CFG_EEPROM_PAGE_WRITE_DELAY_MS: 1490 If defined, the number of milliseconds to delay between 1491 page writes. The default is zero milliseconds. 1492 1493 - CFG_I2C_EEPROM_ADDR_LEN: 1494 The length in bytes of the EEPROM memory array address. Note 1495 that this is NOT the chip address length! 1496 1497 - CFG_EEPROM_SIZE: 1498 The size in bytes of the EEPROM device. 1499 1500- CFG_SPI_INIT_OFFSET 1501 1502 Defines offset to the initial SPI buffer area in DPRAM. The 1503 area is used at an early stage (ROM part) if the environment 1504 is configured to reside in the SPI EEPROM: We need a 520 byte 1505 scratch DPRAM area. It is used between the two initialization 1506 calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems 1507 to be a good choice since it makes it far enough from the 1508 start of the data area as well as from the stack pointer. 1509 1510Please note that the environment is read-only as long as the monitor 1511has been relocated to RAM and a RAM copy of the environment has been 1512created; also, when using EEPROM you will have to use getenv_r() 1513until then to read environment variables. 1514 1515The environment is now protected by a CRC32 checksum. Before the 1516monitor is relocated into RAM, as a result of a bad CRC you will be 1517working with the compiled-in default environment - *silently*!!! 1518[This is necessary, because the first environment variable we need is 1519the "baudrate" setting for the console - if we have a bad CRC, we 1520don't have any device yet where we could complain.] 1521 1522Note: once the monitor has been relocated, then it will complain if 1523the default environment is used; a new CRC is computed as soon as you 1524use the "setenv" command to modify / delete / add any environment 1525variable [even when you try to delete a non-existing variable!]. 1526 1527Note2: you must edit your u-boot.lds file to reflect this 1528configuration. 1529 1530 1531Low Level (hardware related) configuration options: 1532 1533- CFG_CACHELINE_SIZE: 1534 Cache Line Size of the CPU. 1535 1536- CFG_DEFAULT_IMMR: 1537 Default address of the IMMR after system reset. 1538 Needed on some 8260 systems (MPC8260ADS and RPXsuper) 1539 to be able to adjust the position of the IMMR 1540 register after a reset. 1541 1542- Floppy Disk Support: 1543 CFG_FDC_DRIVE_NUMBER 1544 1545 the default drive number (default value 0) 1546 1547 CFG_ISA_IO_STRIDE 1548 1549 defines the spacing between fdc chipset registers 1550 (default value 1) 1551 1552 CFG_ISA_IO_OFFSET 1553 1554 defines the offset of register from address. It 1555 depends on which part of the data bus is connected to 1556 the fdc chipset. (default value 0) 1557 1558 If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and 1559 CFG_FDC_DRIVE_NUMBER are undefined, they take their 1560 default value. 1561 1562 if CFG_FDC_HW_INIT is defined, then the function 1563 fdc_hw_init() is called at the beginning of the FDC 1564 setup. fdc_hw_init() must be provided by the board 1565 source code. It is used to make hardware dependant 1566 initializations. 1567 1568- CFG_IMMR: Physical address of the Internal Memory Mapped 1569 Register; DO NOT CHANGE! (11-4) 1570 [MPC8xx systems only] 1571 1572- CFG_INIT_RAM_ADDR: 1573 1574 Start address of memory area tha can be used for 1575 initial data and stack; please note that this must be 1576 writable memory that is working WITHOUT special 1577 initialization, i. e. you CANNOT use normal RAM which 1578 will become available only after programming the 1579 memory controller and running certain initialization 1580 sequences. 1581 1582 U-Boot uses the following memory types: 1583 - MPC8xx and MPC8260: IMMR (internal memory of the CPU) 1584 - MPC824X: data cache 1585 - PPC4xx: data cache 1586 1587- CFG_INIT_DATA_OFFSET: 1588 1589 Offset of the initial data structure in the memory 1590 area defined by CFG_INIT_RAM_ADDR. Usually 1591 CFG_INIT_DATA_OFFSET is chosen such that the initial 1592 data is located at the end of the available space 1593 (sometimes written as (CFG_INIT_RAM_END - 1594 CFG_INIT_DATA_SIZE), and the initial stack is just 1595 below that area (growing from (CFG_INIT_RAM_ADDR + 1596 CFG_INIT_DATA_OFFSET) downward. 1597 1598 Note: 1599 On the MPC824X (or other systems that use the data 1600 cache for initial memory) the address chosen for 1601 CFG_INIT_RAM_ADDR is basically arbitrary - it must 1602 point to an otherwise UNUSED address space between 1603 the top of RAM and the start of the PCI space. 1604 1605- CFG_SIUMCR: SIU Module Configuration (11-6) 1606 1607- CFG_SYPCR: System Protection Control (11-9) 1608 1609- CFG_TBSCR: Time Base Status and Control (11-26) 1610 1611- CFG_PISCR: Periodic Interrupt Status and Control (11-31) 1612 1613- CFG_PLPRCR: PLL, Low-Power, and Reset Control Register (15-30) 1614 1615- CFG_SCCR: System Clock and reset Control Register (15-27) 1616 1617- CFG_OR_TIMING_SDRAM: 1618 SDRAM timing 1619 1620- CFG_MAMR_PTA: 1621 periodic timer for refresh 1622 1623- CFG_DER: Debug Event Register (37-47) 1624 1625- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM, 1626 CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP, 1627 CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM, 1628 CFG_BR1_PRELIM: 1629 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH) 1630 1631- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE, 1632 CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM, 1633 CFG_OR3_PRELIM, CFG_BR3_PRELIM: 1634 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM) 1635 1636- CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K, 1637 CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL: 1638 Machine Mode Register and Memory Periodic Timer 1639 Prescaler definitions (SDRAM timing) 1640 1641- CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]: 1642 enable I2C microcode relocation patch (MPC8xx); 1643 define relocation offset in DPRAM [DSP2] 1644 1645- CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]: 1646 enable SPI microcode relocation patch (MPC8xx); 1647 define relocation offset in DPRAM [SCC4] 1648 1649- CFG_USE_OSCCLK: 1650 Use OSCM clock mode on MBX8xx board. Be careful, 1651 wrong setting might damage your board. Read 1652 doc/README.MBX before setting this variable! 1653 1654Building the Software: 1655====================== 1656 1657Building U-Boot has been tested in native PPC environments (on a 1658PowerBook G3 running LinuxPPC 2000) and in cross environments 1659(running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and 1660NetBSD 1.5 on x86). 1661 1662If you are not using a native PPC environment, it is assumed that you 1663have the GNU cross compiling tools available in your path and named 1664with a prefix of "powerpc-linux-". If this is not the case, (e.g. if 1665you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change 1666the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU, 1667change it to: 1668 1669 CROSS_COMPILE = ppc_4xx- 1670 1671 1672U-Boot is intended to be simple to build. After installing the 1673sources you must configure U-Boot for one specific board type. This 1674is done by typing: 1675 1676 make NAME_config 1677 1678where "NAME_config" is the name of one of the existing 1679configurations; the following names are supported: 1680 1681 ADCIOP_config GTH_config TQM850L_config 1682 ADS860_config IP860_config TQM855L_config 1683 AR405_config IVML24_config TQM860L_config 1684 CANBT_config IVMS8_config WALNUT405_config 1685 CPCI405_config LANTEC_config cogent_common_config 1686 CPCIISER4_config MBX_config cogent_mpc8260_config 1687 CU824_config MBX860T_config cogent_mpc8xx_config 1688 ESTEEM192E_config RPXlite_config hermes_config 1689 ETX094_config RPXsuper_config hymod_config 1690 FADS823_config SM850_config lwmon_config 1691 FADS850SAR_config SPD823TS_config pcu_e_config 1692 FADS860T_config SXNI855T_config rsdproto_config 1693 FPS850L_config Sandpoint8240_config sbc8260_config 1694 GENIETV_config TQM823L_config PIP405_config 1695 GEN860T_config EBONY_config FPS860L_config 1696 1697Note: for some board special configuration names may exist; check if 1698 additional information is available from the board vendor; for 1699 instance, the TQM8xxL systems run normally at 50 MHz and use a 1700 SCC for 10baseT ethernet; there are also systems with 80 MHz 1701 CPU clock, and an optional Fast Ethernet module is available 1702 for CPU's with FEC. You can select such additional "features" 1703 when chosing the configuration, i. e. 1704 1705 make TQM860L_config 1706 - will configure for a plain TQM860L, i. e. 50MHz, no FEC 1707 1708 make TQM860L_FEC_config 1709 - will configure for a TQM860L at 50MHz with FEC for ethernet 1710 1711 make TQM860L_80MHz_config 1712 - will configure for a TQM860L at 80 MHz, with normal 10baseT 1713 interface 1714 1715 make TQM860L_FEC_80MHz_config 1716 - will configure for a TQM860L at 80 MHz with FEC for ethernet 1717 1718 make TQM823L_LCD_config 1719 - will configure for a TQM823L with U-Boot console on LCD 1720 1721 make TQM823L_LCD_80MHz_config 1722 - will configure for a TQM823L at 80 MHz with U-Boot console on LCD 1723 1724 etc. 1725 1726 1727 1728Finally, type "make all", and you should get some working U-Boot 1729images ready for downlod to / installation on your system: 1730 1731- "u-boot.bin" is a raw binary image 1732- "u-boot" is an image in ELF binary format 1733- "u-boot.srec" is in Motorola S-Record format 1734 1735 1736Please be aware that the Makefiles assume you are using GNU make, so 1737for instance on NetBSD you might need to use "gmake" instead of 1738native "make". 1739 1740 1741If the system board that you have is not listed, then you will need 1742to port U-Boot to your hardware platform. To do this, follow these 1743steps: 1744 17451. Add a new configuration option for your board to the toplevel 1746 "Makefile", using the existing entries as examples. 17472. Create a new directory to hold your board specific code. Add any 1748 files you need. 17493. If you're porting U-Boot to a new CPU, then also create a new 1750 directory to hold your CPU specific code. Add any files you need. 17514. Run "make config_name" with your new name. 17525. Type "make", and you should get a working "u-boot.srec" file 1753 to be installed on your target system. 1754 [Of course, this last step is much harder than it sounds.] 1755 1756 1757Testing of U-Boot Modifications, Ports to New Hardware, etc.: 1758============================================================== 1759 1760If you have modified U-Boot sources (for instance added a new board 1761or support for new devices, a new CPU, etc.) you are expected to 1762provide feedback to the other developers. The feedback normally takes 1763the form of a "patch", i. e. a context diff against a certain (latest 1764official or latest in CVS) version of U-Boot sources. 1765 1766But before you submit such a patch, please verify that your modifi- 1767cation did not break existing code. At least make sure that *ALL* of 1768the supported boards compile WITHOUT ANY compiler warnings. To do so, 1769just run the "MAKEALL" script, which will configure and build U-Boot 1770for ALL supported system. Be warned, this will take a while. You can 1771select which (cross) compiler to use py passing a `CROSS_COMPILE' 1772environment variable to the script, i. e. to use the cross tools from 1773MontaVista's Hard Hat Linux you can type 1774 1775 CROSS_COMPILE=ppc_8xx- MAKEALL 1776 1777or to build on a native PowerPC system you can type 1778 1779 CROSS_COMPILE=' ' MAKEALL 1780 1781See also "U-Boot Porting Guide" below. 1782 1783 1784 1785Monitor Commands - Overview: 1786============================ 1787 1788go - start application at address 'addr' 1789run - run commands in an environment variable 1790bootm - boot application image from memory 1791bootp - boot image via network using BootP/TFTP protocol 1792tftpboot- boot image via network using TFTP protocol 1793 and env variables "ipaddr" and "serverip" 1794 (and eventually "gatewayip") 1795rarpboot- boot image via network using RARP/TFTP protocol 1796diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd' 1797loads - load S-Record file over serial line 1798loadb - load binary file over serial line (kermit mode) 1799md - memory display 1800mm - memory modify (auto-incrementing) 1801nm - memory modify (constant address) 1802mw - memory write (fill) 1803cp - memory copy 1804cmp - memory compare 1805crc32 - checksum calculation 1806imd - i2c memory display 1807imm - i2c memory modify (auto-incrementing) 1808inm - i2c memory modify (constant address) 1809imw - i2c memory write (fill) 1810icrc32 - i2c checksum calculation 1811iprobe - probe to discover valid I2C chip addresses 1812iloop - infinite loop on address range 1813isdram - print SDRAM configuration information 1814sspi - SPI utility commands 1815base - print or set address offset 1816printenv- print environment variables 1817setenv - set environment variables 1818saveenv - save environment variables to persistent storage 1819protect - enable or disable FLASH write protection 1820erase - erase FLASH memory 1821flinfo - print FLASH memory information 1822bdinfo - print Board Info structure 1823iminfo - print header information for application image 1824coninfo - print console devices and informations 1825ide - IDE sub-system 1826loop - infinite loop on address range 1827mtest - simple RAM test 1828icache - enable or disable instruction cache 1829dcache - enable or disable data cache 1830reset - Perform RESET of the CPU 1831echo - echo args to console 1832version - print monitor version 1833help - print online help 1834? - alias for 'help' 1835 1836 1837Monitor Commands - Detailed Description: 1838======================================== 1839 1840TODO. 1841 1842For now: just type "help <command>". 1843 1844 1845Environment Variables: 1846====================== 1847 1848U-Boot supports user configuration using Environment Variables which 1849can be made persistent by saving to Flash memory. 1850 1851Environment Variables are set using "setenv", printed using 1852"printenv", and saved to Flash using "saveenv". Using "setenv" 1853without a value can be used to delete a variable from the 1854environment. As long as you don't save the environment you are 1855working with an in-memory copy. In case the Flash area containing the 1856environment is erased by accident, a default environment is provided. 1857 1858Some configuration options can be set using Environment Variables: 1859 1860 baudrate - see CONFIG_BAUDRATE 1861 1862 bootdelay - see CONFIG_BOOTDELAY 1863 1864 bootcmd - see CONFIG_BOOTCOMMAND 1865 1866 bootargs - Boot arguments when booting an RTOS image 1867 1868 bootfile - Name of the image to load with TFTP 1869 1870 autoload - if set to "no" (any string beginning with 'n'), 1871 "bootp" will just load perform a lookup of the 1872 configuration from the BOOTP server, but not try to 1873 load any image using TFTP 1874 1875 autostart - if set to "yes", an image loaded using the "bootp", 1876 "rarpboot", "tftpboot" or "diskboot" commands will 1877 be automatically started (by internally calling 1878 "bootm") 1879 1880 initrd_high - restrict positioning of initrd images: 1881 If this variable is not set, initrd images will be 1882 copied to the highest possible address in RAM; this 1883 is usually what you want since it allows for 1884 maximum initrd size. If for some reason you want to 1885 make sure that the initrd image is loaded below the 1886 CFG_BOOTMAPSZ limit, you can set this environment 1887 variable to a value of "no" or "off" or "0". 1888 Alternatively, you can set it to a maximum upper 1889 address to use (U-Boot will still check that it 1890 does not overwrite the U-Boot stack and data). 1891 1892 For instance, when you have a system with 16 MB 1893 RAM, and want to reseve 4 MB from use by Linux, 1894 you can do this by adding "mem=12M" to the value of 1895 the "bootargs" variable. However, now you must make 1896 sure, that the initrd image is placed in the first 1897 12 MB as well - this can be done with 1898 1899 setenv initrd_high 00c00000 1900 1901 ipaddr - IP address; needed for tftpboot command 1902 1903 loadaddr - Default load address for commands like "bootp", 1904 "rarpboot", "tftpboot" or "diskboot" 1905 1906 loads_echo - see CONFIG_LOADS_ECHO 1907 1908 serverip - TFTP server IP address; needed for tftpboot command 1909 1910 bootretry - see CONFIG_BOOT_RETRY_TIME 1911 1912 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR 1913 1914 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR 1915 1916 1917The following environment variables may be used and automatically 1918updated by the network boot commands ("bootp" and "rarpboot"), 1919depending the information provided by your boot server: 1920 1921 bootfile - see above 1922 dnsip - IP address of your Domain Name Server 1923 gatewayip - IP address of the Gateway (Router) to use 1924 hostname - Target hostname 1925 ipaddr - see above 1926 netmask - Subnet Mask 1927 rootpath - Pathname of the root filesystem on the NFS server 1928 serverip - see above 1929 1930 1931There are two special Environment Variables: 1932 1933 serial# - contains hardware identification information such 1934 as type string and/or serial number 1935 ethaddr - Ethernet address 1936 1937These variables can be set only once (usually during manufacturing of 1938the board). U-Boot refuses to delete or overwrite these variables 1939once they have been set once. 1940 1941 1942Please note that changes to some configuration parameters may take 1943only effect after the next boot (yes, that's just like Windoze :-). 1944 1945 1946Note for Redundant Ethernet Interfaces: 1947======================================= 1948 1949Some boards come with redundand ethernet interfaces; U-Boot supports 1950such configurations and is capable of automatic selection of a 1951"working" interface when needed. MAC assignemnt works as follows: 1952 1953Network interfaces are numbered eth0, eth1, eth2, ... Corresponding 1954MAC addresses can be stored in the environment as "ethaddr" (=>eth0), 1955"eth1addr" (=>eth1), "eth2addr", ... 1956 1957If the network interface stores some valid MAC address (for instance 1958in SROM), this is used as default address if there is NO correspon- 1959ding setting in the environment; if the corresponding environment 1960variable is set, this overrides the settings in the card; that means: 1961 1962o If the SROM has a valid MAC address, and there is no address in the 1963 environment, the SROM's address is used. 1964 1965o If there is no valid address in the SROM, and a definition in the 1966 environment exists, then the value from the environment variable is 1967 used. 1968 1969o If both the SROM and the environment contain a MAC address, and 1970 both addresses are the same, this MAC address is used. 1971 1972o If both the SROM and the environment contain a MAC address, and the 1973 addresses differ, the value from the environment is used and a 1974 warning is printed. 1975 1976o If neither SROM nor the environment contain a MAC address, an error 1977 is raised. 1978 1979 1980 1981Image Formats: 1982============== 1983 1984The "boot" commands of this monitor operate on "image" files which 1985can be basicly anything, preceeded by a special header; see the 1986definitions in include/image.h for details; basicly, the header 1987defines the following image properties: 1988 1989* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD, 1990 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks, 1991 LynxOS, pSOS, QNX; 1992 Currently supported: Linux, NetBSD, VxWorks, QNX). 1993* Target CPU Architecture (Provisions for Alpha, ARM, Intel x86, 1994 IA64, MIPS, MIPS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit; 1995 Currently supported: PowerPC). 1996* Compression Type (Provisions for uncompressed, gzip, bzip2; 1997 Currently supported: uncompressed, gzip). 1998* Load Address 1999* Entry Point 2000* Image Name 2001* Image Timestamp 2002 2003The header is marked by a special Magic Number, and both the header 2004and the data portions of the image are secured against corruption by 2005CRC32 checksums. 2006 2007 2008Linux Support: 2009============== 2010 2011Although U-Boot should support any OS or standalone application 2012easily, Linux has always been in the focus during the design of 2013U-Boot. 2014 2015U-Boot includes many features that so far have been part of some 2016special "boot loader" code within the Linux kernel. Also, any 2017"initrd" images to be used are no longer part of one big Linux image; 2018instead, kernel and "initrd" are separate images. This implementation 2019serves serveral purposes: 2020 2021- the same features can be used for other OS or standalone 2022 applications (for instance: using compressed images to reduce the 2023 Flash memory footprint) 2024 2025- it becomes much easier to port new Linux kernel versions because 2026 lots of low-level, hardware dependend stuff are done by U-Boot 2027 2028- the same Linux kernel image can now be used with different "initrd" 2029 images; of course this also means that different kernel images can 2030 be run with the same "initrd". This makes testing easier (you don't 2031 have to build a new "zImage.initrd" Linux image when you just 2032 change a file in your "initrd"). Also, a field-upgrade of the 2033 software is easier now. 2034 2035 2036Linux HOWTO: 2037============ 2038 2039Porting Linux to U-Boot based systems: 2040--------------------------------------- 2041 2042U-Boot cannot save you from doing all the necessary modifications to 2043configure the Linux device drivers for use with your target hardware 2044(no, we don't intend to provide a full virtual machine interface to 2045Linux :-). 2046 2047But now you can ignore ALL boot loader code (in arch/ppc/mbxboot). 2048 2049Just make sure your machine specific header file (for instance 2050include/asm-ppc/tqm8xx.h) includes the same definition of the Board 2051Information structure as we define in include/u-boot.h, and make 2052sure that your definition of IMAP_ADDR uses the same value as your 2053U-Boot configuration in CFG_IMMR. 2054 2055 2056Configuring the Linux kernel: 2057----------------------------- 2058 2059No specific requirements for U-Boot. Make sure you have some root 2060device (initial ramdisk, NFS) for your target system. 2061 2062 2063Building a Linux Image: 2064----------------------- 2065 2066With U-Boot, "normal" build targets like "zImage" or "bzImage" are 2067not used. If you use recent kernel source, a new build target 2068"uImage" will exist which automatically builds an image usable by 2069U-Boot. Most older kernels also have support for a "pImage" target, 2070which was introduced for our predecessor project PPCBoot and uses a 2071100% compatible format. 2072 2073Example: 2074 2075 make TQM850L_config 2076 make oldconfig 2077 make dep 2078 make uImage 2079 2080The "uImage" build target uses a special tool (in 'tools/mkimage') to 2081encapsulate a compressed Linux kernel image with header information, 2082CRC32 checksum etc. for use with U-Boot. This is what we are doing: 2083 2084* build a standard "vmlinux" kernel image (in ELF binary format): 2085 2086* convert the kernel into a raw binary image: 2087 2088 ${CROSS_COMPILE}-objcopy -O binary \ 2089 -R .note -R .comment \ 2090 -S vmlinux linux.bin 2091 2092* compress the binary image: 2093 2094 gzip -9 linux.bin 2095 2096* package compressed binary image for U-Boot: 2097 2098 mkimage -A ppc -O linux -T kernel -C gzip \ 2099 -a 0 -e 0 -n "Linux Kernel Image" \ 2100 -d linux.bin.gz uImage 2101 2102 2103The "mkimage" tool can also be used to create ramdisk images for use 2104with U-Boot, either separated from the Linux kernel image, or 2105combined into one file. "mkimage" encapsulates the images with a 64 2106byte header containing information about target architecture, 2107operating system, image type, compression method, entry points, time 2108stamp, CRC32 checksums, etc. 2109 2110"mkimage" can be called in two ways: to verify existing images and 2111print the header information, or to build new images. 2112 2113In the first form (with "-l" option) mkimage lists the information 2114contained in the header of an existing U-Boot image; this includes 2115checksum verification: 2116 2117 tools/mkimage -l image 2118 -l ==> list image header information 2119 2120The second form (with "-d" option) is used to build a U-Boot image 2121from a "data file" which is used as image payload: 2122 2123 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \ 2124 -n name -d data_file image 2125 -A ==> set architecture to 'arch' 2126 -O ==> set operating system to 'os' 2127 -T ==> set image type to 'type' 2128 -C ==> set compression type 'comp' 2129 -a ==> set load address to 'addr' (hex) 2130 -e ==> set entry point to 'ep' (hex) 2131 -n ==> set image name to 'name' 2132 -d ==> use image data from 'datafile' 2133 2134Right now, all Linux kernels use the same load address (0x00000000), 2135but the entry point address depends on the kernel version: 2136 2137- 2.2.x kernels have the entry point at 0x0000000C, 2138- 2.3.x and later kernels have the entry point at 0x00000000. 2139 2140So a typical call to build a U-Boot image would read: 2141 2142 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \ 2143 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \ 2144 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \ 2145 > examples/uImage.TQM850L 2146 Image Name: 2.4.4 kernel for TQM850L 2147 Created: Wed Jul 19 02:34:59 2000 2148 Image Type: PowerPC Linux Kernel Image (gzip compressed) 2149 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB 2150 Load Address: 0x00000000 2151 Entry Point: 0x00000000 2152 2153To verify the contents of the image (or check for corruption): 2154 2155 -> tools/mkimage -l examples/uImage.TQM850L 2156 Image Name: 2.4.4 kernel for TQM850L 2157 Created: Wed Jul 19 02:34:59 2000 2158 Image Type: PowerPC Linux Kernel Image (gzip compressed) 2159 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB 2160 Load Address: 0x00000000 2161 Entry Point: 0x00000000 2162 2163NOTE: for embedded systems where boot time is critical you can trade 2164speed for memory and install an UNCOMPRESSED image instead: this 2165needs more space in Flash, but boots much faster since it does not 2166need to be uncompressed: 2167 2168 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz 2169 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \ 2170 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \ 2171 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \ 2172 > examples/uImage.TQM850L-uncompressed 2173 Image Name: 2.4.4 kernel for TQM850L 2174 Created: Wed Jul 19 02:34:59 2000 2175 Image Type: PowerPC Linux Kernel Image (uncompressed) 2176 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB 2177 Load Address: 0x00000000 2178 Entry Point: 0x00000000 2179 2180 2181Similar you can build U-Boot images from a 'ramdisk.image.gz' file 2182when your kernel is intended to use an initial ramdisk: 2183 2184 -> tools/mkimage -n 'Simple Ramdisk Image' \ 2185 > -A ppc -O linux -T ramdisk -C gzip \ 2186 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd 2187 Image Name: Simple Ramdisk Image 2188 Created: Wed Jan 12 14:01:50 2000 2189 Image Type: PowerPC Linux RAMDisk Image (gzip compressed) 2190 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB 2191 Load Address: 0x00000000 2192 Entry Point: 0x00000000 2193 2194 2195Installing a Linux Image: 2196------------------------- 2197 2198To downloading a U-Boot image over the serial (console) interface, 2199you must convert the image to S-Record format: 2200 2201 objcopy -I binary -O srec examples/image examples/image.srec 2202 2203The 'objcopy' does not understand the information in the U-Boot 2204image header, so the resulting S-Record file will be relative to 2205address 0x00000000. To load it to a given address, you need to 2206specify the target address as 'offset' parameter with the 'loads' 2207command. 2208 2209Example: install the image to address 0x40100000 (which on the 2210TQM8xxL is in the first Flash bank): 2211 2212 => erase 40100000 401FFFFF 2213 2214 .......... done 2215 Erased 8 sectors 2216 2217 => loads 40100000 2218 ## Ready for S-Record download ... 2219 ~>examples/image.srec 2220 1 2 3 4 5 6 7 8 9 10 11 12 13 ... 2221 ... 2222 15989 15990 15991 15992 2223 [file transfer complete] 2224 [connected] 2225 ## Start Addr = 0x00000000 2226 2227 2228You can check the success of the download using the 'iminfo' command; 2229this includes a checksum verification so you can be sure no data 2230corruption happened: 2231 2232 => imi 40100000 2233 2234 ## Checking Image at 40100000 ... 2235 Image Name: 2.2.13 for initrd on TQM850L 2236 Image Type: PowerPC Linux Kernel Image (gzip compressed) 2237 Data Size: 335725 Bytes = 327 kB = 0 MB 2238 Load Address: 00000000 2239 Entry Point: 0000000c 2240 Verifying Checksum ... OK 2241 2242 2243 2244Boot Linux: 2245----------- 2246 2247The "bootm" command is used to boot an application that is stored in 2248memory (RAM or Flash). In case of a Linux kernel image, the contents 2249of the "bootargs" environment variable is passed to the kernel as 2250parameters. You can check and modify this variable using the 2251"printenv" and "setenv" commands: 2252 2253 2254 => printenv bootargs 2255 bootargs=root=/dev/ram 2256 2257 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2 2258 2259 => printenv bootargs 2260 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2 2261 2262 => bootm 40020000 2263 ## Booting Linux kernel at 40020000 ... 2264 Image Name: 2.2.13 for NFS on TQM850L 2265 Image Type: PowerPC Linux Kernel Image (gzip compressed) 2266 Data Size: 381681 Bytes = 372 kB = 0 MB 2267 Load Address: 00000000 2268 Entry Point: 0000000c 2269 Verifying Checksum ... OK 2270 Uncompressing Kernel Image ... OK 2271 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 2272 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2 2273 time_init: decrementer frequency = 187500000/60 2274 Calibrating delay loop... 49.77 BogoMIPS 2275 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000] 2276 ... 2277 2278If you want to boot a Linux kernel with initial ram disk, you pass 2279the memory addreses of both the kernel and the initrd image (PPBCOOT 2280format!) to the "bootm" command: 2281 2282 => imi 40100000 40200000 2283 2284 ## Checking Image at 40100000 ... 2285 Image Name: 2.2.13 for initrd on TQM850L 2286 Image Type: PowerPC Linux Kernel Image (gzip compressed) 2287 Data Size: 335725 Bytes = 327 kB = 0 MB 2288 Load Address: 00000000 2289 Entry Point: 0000000c 2290 Verifying Checksum ... OK 2291 2292 ## Checking Image at 40200000 ... 2293 Image Name: Simple Ramdisk Image 2294 Image Type: PowerPC Linux RAMDisk Image (gzip compressed) 2295 Data Size: 566530 Bytes = 553 kB = 0 MB 2296 Load Address: 00000000 2297 Entry Point: 00000000 2298 Verifying Checksum ... OK 2299 2300 => bootm 40100000 40200000 2301 ## Booting Linux kernel at 40100000 ... 2302 Image Name: 2.2.13 for initrd on TQM850L 2303 Image Type: PowerPC Linux Kernel Image (gzip compressed) 2304 Data Size: 335725 Bytes = 327 kB = 0 MB 2305 Load Address: 00000000 2306 Entry Point: 0000000c 2307 Verifying Checksum ... OK 2308 Uncompressing Kernel Image ... OK 2309 ## Loading RAMDisk Image at 40200000 ... 2310 Image Name: Simple Ramdisk Image 2311 Image Type: PowerPC Linux RAMDisk Image (gzip compressed) 2312 Data Size: 566530 Bytes = 553 kB = 0 MB 2313 Load Address: 00000000 2314 Entry Point: 00000000 2315 Verifying Checksum ... OK 2316 Loading Ramdisk ... OK 2317 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 2318 Boot arguments: root=/dev/ram 2319 time_init: decrementer frequency = 187500000/60 2320 Calibrating delay loop... 49.77 BogoMIPS 2321 ... 2322 RAMDISK: Compressed image found at block 0 2323 VFS: Mounted root (ext2 filesystem). 2324 2325 bash# 2326 2327 2328Standalone HOWTO: 2329================= 2330 2331One of the features of U-Boot is that you can dynamically load and 2332run "standalone" applications, which can use some resources of 2333U-Boot like console I/O functions or interrupt services. 2334 2335Two simple examples are included with the sources: 2336 2337"Hello World" Demo: 2338------------------- 2339 2340'examples/hello_world.c' contains a small "Hello World" Demo 2341application; it is automatically compiled when you build U-Boot. 2342It's configured to run at address 0x00040004, so you can play with it 2343like that: 2344 2345 => loads 2346 ## Ready for S-Record download ... 2347 ~>examples/hello_world.srec 2348 1 2 3 4 5 6 7 8 9 10 11 ... 2349 [file transfer complete] 2350 [connected] 2351 ## Start Addr = 0x00040004 2352 2353 => go 40004 Hello World! This is a test. 2354 ## Starting application at 0x00040004 ... 2355 Hello World 2356 argc = 7 2357 argv[0] = "40004" 2358 argv[1] = "Hello" 2359 argv[2] = "World!" 2360 argv[3] = "This" 2361 argv[4] = "is" 2362 argv[5] = "a" 2363 argv[6] = "test." 2364 argv[7] = "<NULL>" 2365 Hit any key to exit ... 2366 2367 ## Application terminated, rc = 0x0 2368 2369Another example, which demonstrates how to register a CPM interrupt 2370handler with the U-Boot code, can be found in 'examples/timer.c'. 2371Here, a CPM timer is set up to generate an interrupt every second. 2372The interrupt service routine is trivial, just printing a '.' 2373character, but this is just a demo program. The application can be 2374controlled by the following keys: 2375 2376 ? - print current values og the CPM Timer registers 2377 b - enable interrupts and start timer 2378 e - stop timer and disable interrupts 2379 q - quit application 2380 2381 => loads 2382 ## Ready for S-Record download ... 2383 ~>examples/timer.srec 2384 1 2 3 4 5 6 7 8 9 10 11 ... 2385 [file transfer complete] 2386 [connected] 2387 ## Start Addr = 0x00040004 2388 2389 => go 40004 2390 ## Starting application at 0x00040004 ... 2391 TIMERS=0xfff00980 2392 Using timer 1 2393 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0 2394 2395Hit 'b': 2396 [q, b, e, ?] Set interval 1000000 us 2397 Enabling timer 2398Hit '?': 2399 [q, b, e, ?] ........ 2400 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0 2401Hit '?': 2402 [q, b, e, ?] . 2403 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0 2404Hit '?': 2405 [q, b, e, ?] . 2406 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0 2407Hit '?': 2408 [q, b, e, ?] . 2409 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0 2410Hit 'e': 2411 [q, b, e, ?] ...Stopping timer 2412Hit 'q': 2413 [q, b, e, ?] ## Application terminated, rc = 0x0 2414 2415 2416NetBSD Notes: 2417============= 2418 2419Starting at version 0.9.2, U-Boot supports NetBSD both as host 2420(build U-Boot) and target system (boots NetBSD/mpc8xx). 2421 2422Building requires a cross environment; it is known to work on 2423NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also 2424need gmake since the Makefiles are not compatible with BSD make). 2425Note that the cross-powerpc package does not install include files; 2426attempting to build U-Boot will fail because <machine/ansi.h> is 2427missing. This file has to be installed and patched manually: 2428 2429 # cd /usr/pkg/cross/powerpc-netbsd/include 2430 # mkdir powerpc 2431 # ln -s powerpc machine 2432 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h 2433 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST 2434 2435Native builds *don't* work due to incompatibilities between native 2436and U-Boot include files. 2437 2438Booting assumes that (the first part of) the image booted is a 2439stage-2 loader which in turn loads and then invokes the kernel 2440proper. Loader sources will eventually appear in the NetBSD source 2441tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the 2442meantime, send mail to bruno@exet-ag.de and/or wd@denx.de for 2443details. 2444 2445 2446Implementation Internals: 2447========================= 2448 2449The following is not intended to be a complete description of every 2450implementation detail. However, it should help to understand the 2451inner workings of U-Boot and make it easier to port it to custom 2452hardware. 2453 2454 2455Initial Stack, Global Data: 2456--------------------------- 2457 2458The implementation of U-Boot is complicated by the fact that U-Boot 2459starts running out of ROM (flash memory), usually without access to 2460system RAM (because the memory controller is not initialized yet). 2461This means that we don't have writable Data or BSS segments, and BSS 2462is not initialized as zero. To be able to get a C environment working 2463at all, we have to allocate at least a minimal stack. Implementation 2464options for this are defined and restricted by the CPU used: Some CPU 2465models provide on-chip memory (like the IMMR area on MPC8xx and 2466MPC826x processors), on others (parts of) the data cache can be 2467locked as (mis-) used as memory, etc. 2468 2469It is essential to remember this, since it has some impact on the C 2470code for the initialization procedures: 2471 2472* Initialized global data (data segment) is read-only. Do not attempt 2473 to write it. 2474 2475* Do not use any unitialized global data (or implicitely initialized 2476 as zero data - BSS segment) at all - this is undefined, initiali- 2477 zation is performed later (when relocationg to RAM). 2478 2479* Stack space is very limited. Avoid big data buffers or things like 2480 that. 2481 2482Having only the stack as writable memory limits means we cannot use 2483normal global data to share information beween the code. But it 2484turned out that the implementation of U-Boot can be greatly 2485simplified by making a global data structure (gd_t) available to all 2486functions. We could pass a pointer to this data as argument to _all_ 2487functions, but this would bloat the code. Instead we use a feature of 2488the GCC compiler (Global Register Variables) to share the data: we 2489place a pointer (gd) to the global data into a register which we 2490reserve for this purpose. 2491 2492When chosing a register for such a purpose we are restricted by the 2493relevant (E)ABI specifications for the current architecture, and by 2494GCC's implementation. 2495 2496For PowerPC, the following registers have specific use: 2497 R1: stack pointer 2498 R2: TOC pointer 2499 R3-R4: parameter passing and return values 2500 R5-R10: parameter passing 2501 R13: small data area pointer 2502 R30: GOT pointer 2503 R31: frame pointer 2504 2505 (U-Boot also uses R14 as internal GOT pointer.) 2506 2507 ==> U-Boot will use R29 to hold a pointer to the global data 2508 2509 Note: on PPC, we could use a static initializer (since the 2510 address of the global data structure is known at compile time), 2511 but it turned out that reserving a register results in somewhat 2512 smaller code - although the code savings are not that big (on 2513 average for all boards 752 bytes for the whole U-Boot image, 2514 624 text + 127 data). 2515 2516On ARM, the following registers are used: 2517 2518 R0: function argument word/integer result 2519 R1-R3: function argument word 2520 R9: GOT pointer 2521 R10: stack limit (used only if stack checking if enabled) 2522 R11: argument (frame) pointer 2523 R12: temporary workspace 2524 R13: stack pointer 2525 R14: link register 2526 R15: program counter 2527 2528 ==> U-Boot will use R8 to hold a pointer to the global data 2529 2530 2531 2532Memory Management: 2533------------------ 2534 2535U-Boot runs in system state and uses physical addresses, i.e. the 2536MMU is not used either for address mapping nor for memory protection. 2537 2538The available memory is mapped to fixed addresses using the memory 2539controller. In this process, a contiguous block is formed for each 2540memory type (Flash, SDRAM, SRAM), even when it consists of several 2541physical memory banks. 2542 2543U-Boot is installed in the first 128 kB of the first Flash bank (on 2544TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After 2545booting and sizing and initializing DRAM, the code relocates itself 2546to the upper end of DRAM. Immediately below the U-Boot code some 2547memory is reserved for use by malloc() [see CFG_MALLOC_LEN 2548configuration setting]. Below that, a structure with global Board 2549Info data is placed, followed by the stack (growing downward). 2550 2551Additionally, some exception handler code is copied to the low 8 kB 2552of DRAM (0x00000000 ... 0x00001FFF). 2553 2554So a typical memory configuration with 16 MB of DRAM could look like 2555this: 2556 2557 0x0000 0000 Exception Vector code 2558 : 2559 0x0000 1FFF 2560 0x0000 2000 Free for Application Use 2561 : 2562 : 2563 2564 : 2565 : 2566 0x00FB FF20 Monitor Stack (Growing downward) 2567 0x00FB FFAC Board Info Data and permanent copy of global data 2568 0x00FC 0000 Malloc Arena 2569 : 2570 0x00FD FFFF 2571 0x00FE 0000 RAM Copy of Monitor Code 2572 ... eventually: LCD or video framebuffer 2573 ... eventually: pRAM (Protected RAM - unchanged by reset) 2574 0x00FF FFFF [End of RAM] 2575 2576 2577System Initialization: 2578---------------------- 2579 2580In the reset configuration, U-Boot starts at the reset entry point 2581(on most PowerPC systens at address 0x00000100). Because of the reset 2582configuration for CS0# this is a mirror of the onboard Flash memory. 2583To be able to re-map memory U-Boot then jumps to it's link address. 2584To be able to implement the initialization code in C, a (small!) 2585initial stack is set up in the internal Dual Ported RAM (in case CPUs 2586which provide such a feature like MPC8xx or MPC8260), or in a locked 2587part of the data cache. After that, U-Boot initializes the CPU core, 2588the caches and the SIU. 2589 2590Next, all (potentially) available memory banks are mapped using a 2591preliminary mapping. For example, we put them on 512 MB boundaries 2592(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash 2593on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is 2594programmed for SDRAM access. Using the temporary configuration, a 2595simple memory test is run that determines the size of the SDRAM 2596banks. 2597 2598When there is more than one SDRAM bank, and the banks are of 2599different size, the larger is mapped first. For equal size, the first 2600bank (CS2#) is mapped first. The first mapping is always for address 26010x00000000, with any additional banks following immediately to create 2602contiguous memory starting from 0. 2603 2604Then, the monitor installs itself at the upper end of the SDRAM area 2605and allocates memory for use by malloc() and for the global Board 2606Info data; also, the exception vector code is copied to the low RAM 2607pages, and the final stack is set up. 2608 2609Only after this relocation will you have a "normal" C environment; 2610until that you are restricted in several ways, mostly because you are 2611running from ROM, and because the code will have to be relocated to a 2612new address in RAM. 2613 2614 2615U-Boot Porting Guide: 2616---------------------- 2617 2618[Based on messages by Jerry Van Baren in the U-Boot-Users mailing 2619list, Octover 2002] 2620 2621 2622int main (int argc, char *argv[]) 2623{ 2624 sighandler_t no_more_time; 2625 2626 signal (SIGALRM, no_more_time); 2627 alarm (PROJECT_DEADLINE - toSec (3 * WEEK)); 2628 2629 if (available_money > available_manpower) { 2630 pay consultant to port U-Boot; 2631 return 0; 2632 } 2633 2634 Download latest U-Boot source; 2635 2636 if (clueless) { 2637 email ("Hi, I am new to U-Boot, how do I get started?"); 2638 } 2639 2640 while (learning) { 2641 Read the README file in the top level directory; 2642 Read http://www.denx.de/re/DPLG.html 2643 Read the source, Luke; 2644 } 2645 2646 if (available_money > toLocalCurrency ($2500)) { 2647 Buy a BDI2000; 2648 } else { 2649 Add a lot of aggravation and time; 2650 } 2651 2652 Create your own board support subdirectory; 2653 2654 while (!running) { 2655 do { 2656 Add / modify source code; 2657 } until (compiles); 2658 Debug; 2659 if (clueless) 2660 email ("Hi, I am having problems..."); 2661 } 2662 Send patch file to Wolfgang; 2663 2664 return 0; 2665} 2666 2667void no_more_time (int sig) 2668{ 2669 hire_a_guru(); 2670} 2671 2672 2673 2674Coding Standards: 2675----------------- 2676 2677All contributions to U-Boot should conform to the Linux kernel 2678coding style; see the file "Documentation/CodingStyle" in your Linux 2679kernel source directory. 2680 2681Please note that U-Boot is implemented in C (and to some small parts 2682in Assembler); no C++ is used, so please do not use C++ style 2683comments (//) in your code. 2684 2685Submissions which do not conform to the standards may be returned 2686with a request to reformat the changes. 2687 2688 2689Submitting Patches: 2690------------------- 2691 2692Since the number of patches for U-Boot is growing, we need to 2693establish some rules. Submissions which do not conform to these rules 2694may be rejected, even when they contain important and valuable stuff. 2695 2696 2697When you send a patch, please include the following information with 2698it: 2699 2700* For bug fixes: a description of the bug and how your patch fixes 2701 this bug. Please try to include a way of demonstrating that the 2702 patch actually fixes something. 2703 2704* For new features: a description of the feature and your 2705 implementation. 2706 2707* A CHANGELOG entry as plaintext (separate from the patch) 2708 2709* For major contributions, your entry to the CREDITS file 2710 2711* When you add support for a new board, don't forget to add this 2712 board to the MAKEALL script, too. 2713 2714* If your patch adds new configuration options, don't forget to 2715 document these in the README file. 2716 2717* The patch itself. If you are accessing the CVS repository use "cvs 2718 update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your 2719 version of diff does not support these options, then get the latest 2720 version of GNU diff. 2721 2722 We accept patches as plain text, MIME attachments or as uuencoded 2723 gzipped text. 2724 2725Notes: 2726 2727* Before sending the patch, run the MAKEALL script on your patched 2728 source tree and make sure that no errors or warnings are reported 2729 for any of the boards. 2730 2731* Keep your modifications to the necessary minimum: A patch 2732 containing several unrelated changes or arbitrary reformats will be 2733 returned with a request to re-formatting / split it. 2734 2735* If you modify existing code, make sure that your new code does not 2736 add to the memory footprint of the code ;-) Small is beautiful! 2737 When adding new features, these should compile conditionally only 2738 (using #ifdef), and the resulting code with the new feature 2739 disabled must not need more memory than the old code without your 2740 modification. 2741