1# SPDX-License-Identifier: GPL-2.0+ 2# 3# (C) Copyright 2000 - 2013 4# Wolfgang Denk, DENX Software Engineering, wd@denx.de. 5 6Summary: 7======== 8 9This directory contains the source code for U-Boot, a boot loader for 10Embedded boards based on PowerPC, ARM, MIPS and several other 11processors, which can be installed in a boot ROM and used to 12initialize and test the hardware or to download and run application 13code. 14 15The development of U-Boot is closely related to Linux: some parts of 16the source code originate in the Linux source tree, we have some 17header files in common, and special provision has been made to 18support booting of Linux images. 19 20Some attention has been paid to make this software easily 21configurable and extendable. For instance, all monitor commands are 22implemented with the same call interface, so that it's very easy to 23add new commands. Also, instead of permanently adding rarely used 24code (for instance hardware test utilities) to the monitor, you can 25load and run it dynamically. 26 27 28Status: 29======= 30 31In general, all boards for which a configuration option exists in the 32Makefile have been tested to some extent and can be considered 33"working". In fact, many of them are used in production systems. 34 35In case of problems see the CHANGELOG file to find out who contributed 36the specific port. In addition, there are various MAINTAINERS files 37scattered throughout the U-Boot source identifying the people or 38companies responsible for various boards and subsystems. 39 40Note: As of August, 2010, there is no longer a CHANGELOG file in the 41actual U-Boot source tree; however, it can be created dynamically 42from the Git log using: 43 44 make CHANGELOG 45 46 47Where to get help: 48================== 49 50In case you have questions about, problems with or contributions for 51U-Boot, you should send a message to the U-Boot mailing list at 52<u-boot@lists.denx.de>. There is also an archive of previous traffic 53on the mailing list - please search the archive before asking FAQ's. 54Please see http://lists.denx.de/pipermail/u-boot and 55http://dir.gmane.org/gmane.comp.boot-loaders.u-boot 56 57 58Where to get source code: 59========================= 60 61The U-Boot source code is maintained in the Git repository at 62git://www.denx.de/git/u-boot.git ; you can browse it online at 63http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary 64 65The "snapshot" links on this page allow you to download tarballs of 66any version you might be interested in. Official releases are also 67available for FTP download from the ftp://ftp.denx.de/pub/u-boot/ 68directory. 69 70Pre-built (and tested) images are available from 71ftp://ftp.denx.de/pub/u-boot/images/ 72 73 74Where we come from: 75=================== 76 77- start from 8xxrom sources 78- create PPCBoot project (http://sourceforge.net/projects/ppcboot) 79- clean up code 80- make it easier to add custom boards 81- make it possible to add other [PowerPC] CPUs 82- extend functions, especially: 83 * Provide extended interface to Linux boot loader 84 * S-Record download 85 * network boot 86 * PCMCIA / CompactFlash / ATA disk / SCSI ... boot 87- create ARMBoot project (http://sourceforge.net/projects/armboot) 88- add other CPU families (starting with ARM) 89- create U-Boot project (http://sourceforge.net/projects/u-boot) 90- current project page: see http://www.denx.de/wiki/U-Boot 91 92 93Names and Spelling: 94=================== 95 96The "official" name of this project is "Das U-Boot". The spelling 97"U-Boot" shall be used in all written text (documentation, comments 98in source files etc.). Example: 99 100 This is the README file for the U-Boot project. 101 102File names etc. shall be based on the string "u-boot". Examples: 103 104 include/asm-ppc/u-boot.h 105 106 #include <asm/u-boot.h> 107 108Variable names, preprocessor constants etc. shall be either based on 109the string "u_boot" or on "U_BOOT". Example: 110 111 U_BOOT_VERSION u_boot_logo 112 IH_OS_U_BOOT u_boot_hush_start 113 114 115Versioning: 116=========== 117 118Starting with the release in October 2008, the names of the releases 119were changed from numerical release numbers without deeper meaning 120into a time stamp based numbering. Regular releases are identified by 121names consisting of the calendar year and month of the release date. 122Additional fields (if present) indicate release candidates or bug fix 123releases in "stable" maintenance trees. 124 125Examples: 126 U-Boot v2009.11 - Release November 2009 127 U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree 128 U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release 129 130 131Directory Hierarchy: 132==================== 133 134/arch Architecture specific files 135 /arc Files generic to ARC architecture 136 /arm Files generic to ARM architecture 137 /m68k Files generic to m68k architecture 138 /microblaze Files generic to microblaze architecture 139 /mips Files generic to MIPS architecture 140 /nds32 Files generic to NDS32 architecture 141 /nios2 Files generic to Altera NIOS2 architecture 142 /openrisc Files generic to OpenRISC architecture 143 /powerpc Files generic to PowerPC architecture 144 /riscv Files generic to RISC-V architecture 145 /sandbox Files generic to HW-independent "sandbox" 146 /sh Files generic to SH architecture 147 /x86 Files generic to x86 architecture 148/api Machine/arch independent API for external apps 149/board Board dependent files 150/cmd U-Boot commands functions 151/common Misc architecture independent functions 152/configs Board default configuration files 153/disk Code for disk drive partition handling 154/doc Documentation (don't expect too much) 155/drivers Commonly used device drivers 156/dts Contains Makefile for building internal U-Boot fdt. 157/examples Example code for standalone applications, etc. 158/fs Filesystem code (cramfs, ext2, jffs2, etc.) 159/include Header Files 160/lib Library routines generic to all architectures 161/Licenses Various license files 162/net Networking code 163/post Power On Self Test 164/scripts Various build scripts and Makefiles 165/test Various unit test files 166/tools Tools to build S-Record or U-Boot images, etc. 167 168Software Configuration: 169======================= 170 171Configuration is usually done using C preprocessor defines; the 172rationale behind that is to avoid dead code whenever possible. 173 174There are two classes of configuration variables: 175 176* Configuration _OPTIONS_: 177 These are selectable by the user and have names beginning with 178 "CONFIG_". 179 180* Configuration _SETTINGS_: 181 These depend on the hardware etc. and should not be meddled with if 182 you don't know what you're doing; they have names beginning with 183 "CONFIG_SYS_". 184 185Previously, all configuration was done by hand, which involved creating 186symbolic links and editing configuration files manually. More recently, 187U-Boot has added the Kbuild infrastructure used by the Linux kernel, 188allowing you to use the "make menuconfig" command to configure your 189build. 190 191 192Selection of Processor Architecture and Board Type: 193--------------------------------------------------- 194 195For all supported boards there are ready-to-use default 196configurations available; just type "make <board_name>_defconfig". 197 198Example: For a TQM823L module type: 199 200 cd u-boot 201 make TQM823L_defconfig 202 203Note: If you're looking for the default configuration file for a board 204you're sure used to be there but is now missing, check the file 205doc/README.scrapyard for a list of no longer supported boards. 206 207Sandbox Environment: 208-------------------- 209 210U-Boot can be built natively to run on a Linux host using the 'sandbox' 211board. This allows feature development which is not board- or architecture- 212specific to be undertaken on a native platform. The sandbox is also used to 213run some of U-Boot's tests. 214 215See board/sandbox/README.sandbox for more details. 216 217 218Board Initialisation Flow: 219-------------------------- 220 221This is the intended start-up flow for boards. This should apply for both 222SPL and U-Boot proper (i.e. they both follow the same rules). 223 224Note: "SPL" stands for "Secondary Program Loader," which is explained in 225more detail later in this file. 226 227At present, SPL mostly uses a separate code path, but the function names 228and roles of each function are the same. Some boards or architectures 229may not conform to this. At least most ARM boards which use 230CONFIG_SPL_FRAMEWORK conform to this. 231 232Execution typically starts with an architecture-specific (and possibly 233CPU-specific) start.S file, such as: 234 235 - arch/arm/cpu/armv7/start.S 236 - arch/powerpc/cpu/mpc83xx/start.S 237 - arch/mips/cpu/start.S 238 239and so on. From there, three functions are called; the purpose and 240limitations of each of these functions are described below. 241 242lowlevel_init(): 243 - purpose: essential init to permit execution to reach board_init_f() 244 - no global_data or BSS 245 - there is no stack (ARMv7 may have one but it will soon be removed) 246 - must not set up SDRAM or use console 247 - must only do the bare minimum to allow execution to continue to 248 board_init_f() 249 - this is almost never needed 250 - return normally from this function 251 252board_init_f(): 253 - purpose: set up the machine ready for running board_init_r(): 254 i.e. SDRAM and serial UART 255 - global_data is available 256 - stack is in SRAM 257 - BSS is not available, so you cannot use global/static variables, 258 only stack variables and global_data 259 260 Non-SPL-specific notes: 261 - dram_init() is called to set up DRAM. If already done in SPL this 262 can do nothing 263 264 SPL-specific notes: 265 - you can override the entire board_init_f() function with your own 266 version as needed. 267 - preloader_console_init() can be called here in extremis 268 - should set up SDRAM, and anything needed to make the UART work 269 - these is no need to clear BSS, it will be done by crt0.S 270 - must return normally from this function (don't call board_init_r() 271 directly) 272 273Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at 274this point the stack and global_data are relocated to below 275CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of 276memory. 277 278board_init_r(): 279 - purpose: main execution, common code 280 - global_data is available 281 - SDRAM is available 282 - BSS is available, all static/global variables can be used 283 - execution eventually continues to main_loop() 284 285 Non-SPL-specific notes: 286 - U-Boot is relocated to the top of memory and is now running from 287 there. 288 289 SPL-specific notes: 290 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and 291 CONFIG_SPL_STACK_R_ADDR points into SDRAM 292 - preloader_console_init() can be called here - typically this is 293 done by selecting CONFIG_SPL_BOARD_INIT and then supplying a 294 spl_board_init() function containing this call 295 - loads U-Boot or (in falcon mode) Linux 296 297 298 299Configuration Options: 300---------------------- 301 302Configuration depends on the combination of board and CPU type; all 303such information is kept in a configuration file 304"include/configs/<board_name>.h". 305 306Example: For a TQM823L module, all configuration settings are in 307"include/configs/TQM823L.h". 308 309 310Many of the options are named exactly as the corresponding Linux 311kernel configuration options. The intention is to make it easier to 312build a config tool - later. 313 314- ARM Platform Bus Type(CCI): 315 CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which 316 provides full cache coherency between two clusters of multi-core 317 CPUs and I/O coherency for devices and I/O masters 318 319 CONFIG_SYS_FSL_HAS_CCI400 320 321 Defined For SoC that has cache coherent interconnect 322 CCN-400 323 324 CONFIG_SYS_FSL_HAS_CCN504 325 326 Defined for SoC that has cache coherent interconnect CCN-504 327 328The following options need to be configured: 329 330- CPU Type: Define exactly one, e.g. CONFIG_MPC85XX. 331 332- Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS. 333 334- 85xx CPU Options: 335 CONFIG_SYS_PPC64 336 337 Specifies that the core is a 64-bit PowerPC implementation (implements 338 the "64" category of the Power ISA). This is necessary for ePAPR 339 compliance, among other possible reasons. 340 341 CONFIG_SYS_FSL_TBCLK_DIV 342 343 Defines the core time base clock divider ratio compared to the 344 system clock. On most PQ3 devices this is 8, on newer QorIQ 345 devices it can be 16 or 32. The ratio varies from SoC to Soc. 346 347 CONFIG_SYS_FSL_PCIE_COMPAT 348 349 Defines the string to utilize when trying to match PCIe device 350 tree nodes for the given platform. 351 352 CONFIG_SYS_FSL_ERRATUM_A004510 353 354 Enables a workaround for erratum A004510. If set, 355 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and 356 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set. 357 358 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV 359 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional) 360 361 Defines one or two SoC revisions (low 8 bits of SVR) 362 for which the A004510 workaround should be applied. 363 364 The rest of SVR is either not relevant to the decision 365 of whether the erratum is present (e.g. p2040 versus 366 p2041) or is implied by the build target, which controls 367 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set. 368 369 See Freescale App Note 4493 for more information about 370 this erratum. 371 372 CONFIG_A003399_NOR_WORKAROUND 373 Enables a workaround for IFC erratum A003399. It is only 374 required during NOR boot. 375 376 CONFIG_A008044_WORKAROUND 377 Enables a workaround for T1040/T1042 erratum A008044. It is only 378 required during NAND boot and valid for Rev 1.0 SoC revision 379 380 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY 381 382 This is the value to write into CCSR offset 0x18600 383 according to the A004510 workaround. 384 385 CONFIG_SYS_FSL_DSP_DDR_ADDR 386 This value denotes start offset of DDR memory which is 387 connected exclusively to the DSP cores. 388 389 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR 390 This value denotes start offset of M2 memory 391 which is directly connected to the DSP core. 392 393 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR 394 This value denotes start offset of M3 memory which is directly 395 connected to the DSP core. 396 397 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT 398 This value denotes start offset of DSP CCSR space. 399 400 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK 401 Single Source Clock is clocking mode present in some of FSL SoC's. 402 In this mode, a single differential clock is used to supply 403 clocks to the sysclock, ddrclock and usbclock. 404 405 CONFIG_SYS_CPC_REINIT_F 406 This CONFIG is defined when the CPC is configured as SRAM at the 407 time of U-Boot entry and is required to be re-initialized. 408 409 CONFIG_DEEP_SLEEP 410 Indicates this SoC supports deep sleep feature. If deep sleep is 411 supported, core will start to execute uboot when wakes up. 412 413- Generic CPU options: 414 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN 415 416 Defines the endianess of the CPU. Implementation of those 417 values is arch specific. 418 419 CONFIG_SYS_FSL_DDR 420 Freescale DDR driver in use. This type of DDR controller is 421 found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core 422 SoCs. 423 424 CONFIG_SYS_FSL_DDR_ADDR 425 Freescale DDR memory-mapped register base. 426 427 CONFIG_SYS_FSL_DDR_EMU 428 Specify emulator support for DDR. Some DDR features such as 429 deskew training are not available. 430 431 CONFIG_SYS_FSL_DDRC_GEN1 432 Freescale DDR1 controller. 433 434 CONFIG_SYS_FSL_DDRC_GEN2 435 Freescale DDR2 controller. 436 437 CONFIG_SYS_FSL_DDRC_GEN3 438 Freescale DDR3 controller. 439 440 CONFIG_SYS_FSL_DDRC_GEN4 441 Freescale DDR4 controller. 442 443 CONFIG_SYS_FSL_DDRC_ARM_GEN3 444 Freescale DDR3 controller for ARM-based SoCs. 445 446 CONFIG_SYS_FSL_DDR1 447 Board config to use DDR1. It can be enabled for SoCs with 448 Freescale DDR1 or DDR2 controllers, depending on the board 449 implemetation. 450 451 CONFIG_SYS_FSL_DDR2 452 Board config to use DDR2. It can be enabled for SoCs with 453 Freescale DDR2 or DDR3 controllers, depending on the board 454 implementation. 455 456 CONFIG_SYS_FSL_DDR3 457 Board config to use DDR3. It can be enabled for SoCs with 458 Freescale DDR3 or DDR3L controllers. 459 460 CONFIG_SYS_FSL_DDR3L 461 Board config to use DDR3L. It can be enabled for SoCs with 462 DDR3L controllers. 463 464 CONFIG_SYS_FSL_DDR4 465 Board config to use DDR4. It can be enabled for SoCs with 466 DDR4 controllers. 467 468 CONFIG_SYS_FSL_IFC_BE 469 Defines the IFC controller register space as Big Endian 470 471 CONFIG_SYS_FSL_IFC_LE 472 Defines the IFC controller register space as Little Endian 473 474 CONFIG_SYS_FSL_IFC_CLK_DIV 475 Defines divider of platform clock(clock input to IFC controller). 476 477 CONFIG_SYS_FSL_LBC_CLK_DIV 478 Defines divider of platform clock(clock input to eLBC controller). 479 480 CONFIG_SYS_FSL_PBL_PBI 481 It enables addition of RCW (Power on reset configuration) in built image. 482 Please refer doc/README.pblimage for more details 483 484 CONFIG_SYS_FSL_PBL_RCW 485 It adds PBI(pre-boot instructions) commands in u-boot build image. 486 PBI commands can be used to configure SoC before it starts the execution. 487 Please refer doc/README.pblimage for more details 488 489 CONFIG_SPL_FSL_PBL 490 It adds a target to create boot binary having SPL binary in PBI format 491 concatenated with u-boot binary. 492 493 CONFIG_SYS_FSL_DDR_BE 494 Defines the DDR controller register space as Big Endian 495 496 CONFIG_SYS_FSL_DDR_LE 497 Defines the DDR controller register space as Little Endian 498 499 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY 500 Physical address from the view of DDR controllers. It is the 501 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But 502 it could be different for ARM SoCs. 503 504 CONFIG_SYS_FSL_DDR_INTLV_256B 505 DDR controller interleaving on 256-byte. This is a special 506 interleaving mode, handled by Dickens for Freescale layerscape 507 SoCs with ARM core. 508 509 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS 510 Number of controllers used as main memory. 511 512 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS 513 Number of controllers used for other than main memory. 514 515 CONFIG_SYS_FSL_HAS_DP_DDR 516 Defines the SoC has DP-DDR used for DPAA. 517 518 CONFIG_SYS_FSL_SEC_BE 519 Defines the SEC controller register space as Big Endian 520 521 CONFIG_SYS_FSL_SEC_LE 522 Defines the SEC controller register space as Little Endian 523 524- MIPS CPU options: 525 CONFIG_SYS_INIT_SP_OFFSET 526 527 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack 528 pointer. This is needed for the temporary stack before 529 relocation. 530 531 CONFIG_XWAY_SWAP_BYTES 532 533 Enable compilation of tools/xway-swap-bytes needed for Lantiq 534 XWAY SoCs for booting from NOR flash. The U-Boot image needs to 535 be swapped if a flash programmer is used. 536 537- ARM options: 538 CONFIG_SYS_EXCEPTION_VECTORS_HIGH 539 540 Select high exception vectors of the ARM core, e.g., do not 541 clear the V bit of the c1 register of CP15. 542 543 COUNTER_FREQUENCY 544 Generic timer clock source frequency. 545 546 COUNTER_FREQUENCY_REAL 547 Generic timer clock source frequency if the real clock is 548 different from COUNTER_FREQUENCY, and can only be determined 549 at run time. 550 551- Tegra SoC options: 552 CONFIG_TEGRA_SUPPORT_NON_SECURE 553 554 Support executing U-Boot in non-secure (NS) mode. Certain 555 impossible actions will be skipped if the CPU is in NS mode, 556 such as ARM architectural timer initialization. 557 558- Linux Kernel Interface: 559 CONFIG_CLOCKS_IN_MHZ 560 561 U-Boot stores all clock information in Hz 562 internally. For binary compatibility with older Linux 563 kernels (which expect the clocks passed in the 564 bd_info data to be in MHz) the environment variable 565 "clocks_in_mhz" can be defined so that U-Boot 566 converts clock data to MHZ before passing it to the 567 Linux kernel. 568 When CONFIG_CLOCKS_IN_MHZ is defined, a definition of 569 "clocks_in_mhz=1" is automatically included in the 570 default environment. 571 572 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only] 573 574 When transferring memsize parameter to Linux, some versions 575 expect it to be in bytes, others in MB. 576 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes. 577 578 CONFIG_OF_LIBFDT 579 580 New kernel versions are expecting firmware settings to be 581 passed using flattened device trees (based on open firmware 582 concepts). 583 584 CONFIG_OF_LIBFDT 585 * New libfdt-based support 586 * Adds the "fdt" command 587 * The bootm command automatically updates the fdt 588 589 OF_TBCLK - The timebase frequency. 590 OF_STDOUT_PATH - The path to the console device 591 592 boards with QUICC Engines require OF_QE to set UCC MAC 593 addresses 594 595 CONFIG_OF_BOARD_SETUP 596 597 Board code has addition modification that it wants to make 598 to the flat device tree before handing it off to the kernel 599 600 CONFIG_OF_SYSTEM_SETUP 601 602 Other code has addition modification that it wants to make 603 to the flat device tree before handing it off to the kernel. 604 This causes ft_system_setup() to be called before booting 605 the kernel. 606 607 CONFIG_OF_IDE_FIXUP 608 609 U-Boot can detect if an IDE device is present or not. 610 If not, and this new config option is activated, U-Boot 611 removes the ATA node from the DTS before booting Linux, 612 so the Linux IDE driver does not probe the device and 613 crash. This is needed for buggy hardware (uc101) where 614 no pull down resistor is connected to the signal IDE5V_DD7. 615 616 CONFIG_MACH_TYPE [relevant for ARM only][mandatory] 617 618 This setting is mandatory for all boards that have only one 619 machine type and must be used to specify the machine type 620 number as it appears in the ARM machine registry 621 (see http://www.arm.linux.org.uk/developer/machines/). 622 Only boards that have multiple machine types supported 623 in a single configuration file and the machine type is 624 runtime discoverable, do not have to use this setting. 625 626- vxWorks boot parameters: 627 628 bootvx constructs a valid bootline using the following 629 environments variables: bootdev, bootfile, ipaddr, netmask, 630 serverip, gatewayip, hostname, othbootargs. 631 It loads the vxWorks image pointed bootfile. 632 633 Note: If a "bootargs" environment is defined, it will overwride 634 the defaults discussed just above. 635 636- Cache Configuration: 637 CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot 638 639- Cache Configuration for ARM: 640 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache 641 controller 642 CONFIG_SYS_PL310_BASE - Physical base address of PL310 643 controller register space 644 645- Serial Ports: 646 CONFIG_PL010_SERIAL 647 648 Define this if you want support for Amba PrimeCell PL010 UARTs. 649 650 CONFIG_PL011_SERIAL 651 652 Define this if you want support for Amba PrimeCell PL011 UARTs. 653 654 CONFIG_PL011_CLOCK 655 656 If you have Amba PrimeCell PL011 UARTs, set this variable to 657 the clock speed of the UARTs. 658 659 CONFIG_PL01x_PORTS 660 661 If you have Amba PrimeCell PL010 or PL011 UARTs on your board, 662 define this to a list of base addresses for each (supported) 663 port. See e.g. include/configs/versatile.h 664 665 CONFIG_SERIAL_HW_FLOW_CONTROL 666 667 Define this variable to enable hw flow control in serial driver. 668 Current user of this option is drivers/serial/nsl16550.c driver 669 670- Console Baudrate: 671 CONFIG_BAUDRATE - in bps 672 Select one of the baudrates listed in 673 CONFIG_SYS_BAUDRATE_TABLE, see below. 674 675- Autoboot Command: 676 CONFIG_BOOTCOMMAND 677 Only needed when CONFIG_BOOTDELAY is enabled; 678 define a command string that is automatically executed 679 when no character is read on the console interface 680 within "Boot Delay" after reset. 681 682 CONFIG_RAMBOOT and CONFIG_NFSBOOT 683 The value of these goes into the environment as 684 "ramboot" and "nfsboot" respectively, and can be used 685 as a convenience, when switching between booting from 686 RAM and NFS. 687 688- Serial Download Echo Mode: 689 CONFIG_LOADS_ECHO 690 If defined to 1, all characters received during a 691 serial download (using the "loads" command) are 692 echoed back. This might be needed by some terminal 693 emulations (like "cu"), but may as well just take 694 time on others. This setting #define's the initial 695 value of the "loads_echo" environment variable. 696 697- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined) 698 CONFIG_KGDB_BAUDRATE 699 Select one of the baudrates listed in 700 CONFIG_SYS_BAUDRATE_TABLE, see below. 701 702- Removal of commands 703 If no commands are needed to boot, you can disable 704 CONFIG_CMDLINE to remove them. In this case, the command line 705 will not be available, and when U-Boot wants to execute the 706 boot command (on start-up) it will call board_run_command() 707 instead. This can reduce image size significantly for very 708 simple boot procedures. 709 710- Regular expression support: 711 CONFIG_REGEX 712 If this variable is defined, U-Boot is linked against 713 the SLRE (Super Light Regular Expression) library, 714 which adds regex support to some commands, as for 715 example "env grep" and "setexpr". 716 717- Device tree: 718 CONFIG_OF_CONTROL 719 If this variable is defined, U-Boot will use a device tree 720 to configure its devices, instead of relying on statically 721 compiled #defines in the board file. This option is 722 experimental and only available on a few boards. The device 723 tree is available in the global data as gd->fdt_blob. 724 725 U-Boot needs to get its device tree from somewhere. This can 726 be done using one of the three options below: 727 728 CONFIG_OF_EMBED 729 If this variable is defined, U-Boot will embed a device tree 730 binary in its image. This device tree file should be in the 731 board directory and called <soc>-<board>.dts. The binary file 732 is then picked up in board_init_f() and made available through 733 the global data structure as gd->fdt_blob. 734 735 CONFIG_OF_SEPARATE 736 If this variable is defined, U-Boot will build a device tree 737 binary. It will be called u-boot.dtb. Architecture-specific 738 code will locate it at run-time. Generally this works by: 739 740 cat u-boot.bin u-boot.dtb >image.bin 741 742 and in fact, U-Boot does this for you, creating a file called 743 u-boot-dtb.bin which is useful in the common case. You can 744 still use the individual files if you need something more 745 exotic. 746 747 CONFIG_OF_BOARD 748 If this variable is defined, U-Boot will use the device tree 749 provided by the board at runtime instead of embedding one with 750 the image. Only boards defining board_fdt_blob_setup() support 751 this option (see include/fdtdec.h file). 752 753- Watchdog: 754 CONFIG_WATCHDOG 755 If this variable is defined, it enables watchdog 756 support for the SoC. There must be support in the SoC 757 specific code for a watchdog. For the 8xx 758 CPUs, the SIU Watchdog feature is enabled in the SYPCR 759 register. When supported for a specific SoC is 760 available, then no further board specific code should 761 be needed to use it. 762 763 CONFIG_HW_WATCHDOG 764 When using a watchdog circuitry external to the used 765 SoC, then define this variable and provide board 766 specific code for the "hw_watchdog_reset" function. 767 768 CONFIG_AT91_HW_WDT_TIMEOUT 769 specify the timeout in seconds. default 2 seconds. 770 771- Real-Time Clock: 772 773 When CONFIG_CMD_DATE is selected, the type of the RTC 774 has to be selected, too. Define exactly one of the 775 following options: 776 777 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC 778 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC 779 CONFIG_RTC_MC146818 - use MC146818 RTC 780 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC 781 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC 782 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC 783 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC 784 CONFIG_RTC_DS164x - use Dallas DS164x RTC 785 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC 786 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC 787 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337 788 CONFIG_SYS_RV3029_TCR - enable trickle charger on 789 RV3029 RTC. 790 791 Note that if the RTC uses I2C, then the I2C interface 792 must also be configured. See I2C Support, below. 793 794- GPIO Support: 795 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO 796 797 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of 798 chip-ngpio pairs that tell the PCA953X driver the number of 799 pins supported by a particular chip. 800 801 Note that if the GPIO device uses I2C, then the I2C interface 802 must also be configured. See I2C Support, below. 803 804- I/O tracing: 805 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O 806 accesses and can checksum them or write a list of them out 807 to memory. See the 'iotrace' command for details. This is 808 useful for testing device drivers since it can confirm that 809 the driver behaves the same way before and after a code 810 change. Currently this is supported on sandbox and arm. To 811 add support for your architecture, add '#include <iotrace.h>' 812 to the bottom of arch/<arch>/include/asm/io.h and test. 813 814 Example output from the 'iotrace stats' command is below. 815 Note that if the trace buffer is exhausted, the checksum will 816 still continue to operate. 817 818 iotrace is enabled 819 Start: 10000000 (buffer start address) 820 Size: 00010000 (buffer size) 821 Offset: 00000120 (current buffer offset) 822 Output: 10000120 (start + offset) 823 Count: 00000018 (number of trace records) 824 CRC32: 9526fb66 (CRC32 of all trace records) 825 826- Timestamp Support: 827 828 When CONFIG_TIMESTAMP is selected, the timestamp 829 (date and time) of an image is printed by image 830 commands like bootm or iminfo. This option is 831 automatically enabled when you select CONFIG_CMD_DATE . 832 833- Partition Labels (disklabels) Supported: 834 Zero or more of the following: 835 CONFIG_MAC_PARTITION Apple's MacOS partition table. 836 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc. 837 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the 838 bootloader. Note 2TB partition limit; see 839 disk/part_efi.c 840 CONFIG_SCSI) you must configure support for at 841 least one non-MTD partition type as well. 842 843- IDE Reset method: 844 CONFIG_IDE_RESET_ROUTINE - this is defined in several 845 board configurations files but used nowhere! 846 847 CONFIG_IDE_RESET - is this is defined, IDE Reset will 848 be performed by calling the function 849 ide_set_reset(int reset) 850 which has to be defined in a board specific file 851 852- ATAPI Support: 853 CONFIG_ATAPI 854 855 Set this to enable ATAPI support. 856 857- LBA48 Support 858 CONFIG_LBA48 859 860 Set this to enable support for disks larger than 137GB 861 Also look at CONFIG_SYS_64BIT_LBA. 862 Whithout these , LBA48 support uses 32bit variables and will 'only' 863 support disks up to 2.1TB. 864 865 CONFIG_SYS_64BIT_LBA: 866 When enabled, makes the IDE subsystem use 64bit sector addresses. 867 Default is 32bit. 868 869- SCSI Support: 870 CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and 871 CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID * 872 CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the 873 maximum numbers of LUNs, SCSI ID's and target 874 devices. 875 876 The environment variable 'scsidevs' is set to the number of 877 SCSI devices found during the last scan. 878 879- NETWORK Support (PCI): 880 CONFIG_E1000 881 Support for Intel 8254x/8257x gigabit chips. 882 883 CONFIG_E1000_SPI 884 Utility code for direct access to the SPI bus on Intel 8257x. 885 This does not do anything useful unless you set at least one 886 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC. 887 888 CONFIG_E1000_SPI_GENERIC 889 Allow generic access to the SPI bus on the Intel 8257x, for 890 example with the "sspi" command. 891 892 CONFIG_EEPRO100 893 Support for Intel 82557/82559/82559ER chips. 894 Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM 895 write routine for first time initialisation. 896 897 CONFIG_TULIP 898 Support for Digital 2114x chips. 899 Optional CONFIG_TULIP_SELECT_MEDIA for board specific 900 modem chip initialisation (KS8761/QS6611). 901 902 CONFIG_NATSEMI 903 Support for National dp83815 chips. 904 905 CONFIG_NS8382X 906 Support for National dp8382[01] gigabit chips. 907 908- NETWORK Support (other): 909 910 CONFIG_DRIVER_AT91EMAC 911 Support for AT91RM9200 EMAC. 912 913 CONFIG_RMII 914 Define this to use reduced MII inteface 915 916 CONFIG_DRIVER_AT91EMAC_QUIET 917 If this defined, the driver is quiet. 918 The driver doen't show link status messages. 919 920 CONFIG_CALXEDA_XGMAC 921 Support for the Calxeda XGMAC device 922 923 CONFIG_LAN91C96 924 Support for SMSC's LAN91C96 chips. 925 926 CONFIG_LAN91C96_USE_32_BIT 927 Define this to enable 32 bit addressing 928 929 CONFIG_SMC91111 930 Support for SMSC's LAN91C111 chip 931 932 CONFIG_SMC91111_BASE 933 Define this to hold the physical address 934 of the device (I/O space) 935 936 CONFIG_SMC_USE_32_BIT 937 Define this if data bus is 32 bits 938 939 CONFIG_SMC_USE_IOFUNCS 940 Define this to use i/o functions instead of macros 941 (some hardware wont work with macros) 942 943 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT 944 Define this if you have more then 3 PHYs. 945 946 CONFIG_FTGMAC100 947 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet 948 949 CONFIG_FTGMAC100_EGIGA 950 Define this to use GE link update with gigabit PHY. 951 Define this if FTGMAC100 is connected to gigabit PHY. 952 If your system has 10/100 PHY only, it might not occur 953 wrong behavior. Because PHY usually return timeout or 954 useless data when polling gigabit status and gigabit 955 control registers. This behavior won't affect the 956 correctnessof 10/100 link speed update. 957 958 CONFIG_SH_ETHER 959 Support for Renesas on-chip Ethernet controller 960 961 CONFIG_SH_ETHER_USE_PORT 962 Define the number of ports to be used 963 964 CONFIG_SH_ETHER_PHY_ADDR 965 Define the ETH PHY's address 966 967 CONFIG_SH_ETHER_CACHE_WRITEBACK 968 If this option is set, the driver enables cache flush. 969 970- PWM Support: 971 CONFIG_PWM_IMX 972 Support for PWM module on the imx6. 973 974- TPM Support: 975 CONFIG_TPM 976 Support TPM devices. 977 978 CONFIG_TPM_TIS_INFINEON 979 Support for Infineon i2c bus TPM devices. Only one device 980 per system is supported at this time. 981 982 CONFIG_TPM_TIS_I2C_BURST_LIMITATION 983 Define the burst count bytes upper limit 984 985 CONFIG_TPM_ST33ZP24 986 Support for STMicroelectronics TPM devices. Requires DM_TPM support. 987 988 CONFIG_TPM_ST33ZP24_I2C 989 Support for STMicroelectronics ST33ZP24 I2C devices. 990 Requires TPM_ST33ZP24 and I2C. 991 992 CONFIG_TPM_ST33ZP24_SPI 993 Support for STMicroelectronics ST33ZP24 SPI devices. 994 Requires TPM_ST33ZP24 and SPI. 995 996 CONFIG_TPM_ATMEL_TWI 997 Support for Atmel TWI TPM device. Requires I2C support. 998 999 CONFIG_TPM_TIS_LPC 1000 Support for generic parallel port TPM devices. Only one device 1001 per system is supported at this time. 1002 1003 CONFIG_TPM_TIS_BASE_ADDRESS 1004 Base address where the generic TPM device is mapped 1005 to. Contemporary x86 systems usually map it at 1006 0xfed40000. 1007 1008 CONFIG_TPM 1009 Define this to enable the TPM support library which provides 1010 functional interfaces to some TPM commands. 1011 Requires support for a TPM device. 1012 1013 CONFIG_TPM_AUTH_SESSIONS 1014 Define this to enable authorized functions in the TPM library. 1015 Requires CONFIG_TPM and CONFIG_SHA1. 1016 1017- USB Support: 1018 At the moment only the UHCI host controller is 1019 supported (PIP405, MIP405); define 1020 CONFIG_USB_UHCI to enable it. 1021 define CONFIG_USB_KEYBOARD to enable the USB Keyboard 1022 and define CONFIG_USB_STORAGE to enable the USB 1023 storage devices. 1024 Note: 1025 Supported are USB Keyboards and USB Floppy drives 1026 (TEAC FD-05PUB). 1027 1028 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the 1029 txfilltuning field in the EHCI controller on reset. 1030 1031 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2 1032 HW module registers. 1033 1034- USB Device: 1035 Define the below if you wish to use the USB console. 1036 Once firmware is rebuilt from a serial console issue the 1037 command "setenv stdin usbtty; setenv stdout usbtty" and 1038 attach your USB cable. The Unix command "dmesg" should print 1039 it has found a new device. The environment variable usbtty 1040 can be set to gserial or cdc_acm to enable your device to 1041 appear to a USB host as a Linux gserial device or a 1042 Common Device Class Abstract Control Model serial device. 1043 If you select usbtty = gserial you should be able to enumerate 1044 a Linux host by 1045 # modprobe usbserial vendor=0xVendorID product=0xProductID 1046 else if using cdc_acm, simply setting the environment 1047 variable usbtty to be cdc_acm should suffice. The following 1048 might be defined in YourBoardName.h 1049 1050 CONFIG_USB_DEVICE 1051 Define this to build a UDC device 1052 1053 CONFIG_USB_TTY 1054 Define this to have a tty type of device available to 1055 talk to the UDC device 1056 1057 CONFIG_USBD_HS 1058 Define this to enable the high speed support for usb 1059 device and usbtty. If this feature is enabled, a routine 1060 int is_usbd_high_speed(void) 1061 also needs to be defined by the driver to dynamically poll 1062 whether the enumeration has succeded at high speed or full 1063 speed. 1064 1065 CONFIG_SYS_CONSOLE_IS_IN_ENV 1066 Define this if you want stdin, stdout &/or stderr to 1067 be set to usbtty. 1068 1069 If you have a USB-IF assigned VendorID then you may wish to 1070 define your own vendor specific values either in BoardName.h 1071 or directly in usbd_vendor_info.h. If you don't define 1072 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME, 1073 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot 1074 should pretend to be a Linux device to it's target host. 1075 1076 CONFIG_USBD_MANUFACTURER 1077 Define this string as the name of your company for 1078 - CONFIG_USBD_MANUFACTURER "my company" 1079 1080 CONFIG_USBD_PRODUCT_NAME 1081 Define this string as the name of your product 1082 - CONFIG_USBD_PRODUCT_NAME "acme usb device" 1083 1084 CONFIG_USBD_VENDORID 1085 Define this as your assigned Vendor ID from the USB 1086 Implementors Forum. This *must* be a genuine Vendor ID 1087 to avoid polluting the USB namespace. 1088 - CONFIG_USBD_VENDORID 0xFFFF 1089 1090 CONFIG_USBD_PRODUCTID 1091 Define this as the unique Product ID 1092 for your device 1093 - CONFIG_USBD_PRODUCTID 0xFFFF 1094 1095- ULPI Layer Support: 1096 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via 1097 the generic ULPI layer. The generic layer accesses the ULPI PHY 1098 via the platform viewport, so you need both the genric layer and 1099 the viewport enabled. Currently only Chipidea/ARC based 1100 viewport is supported. 1101 To enable the ULPI layer support, define CONFIG_USB_ULPI and 1102 CONFIG_USB_ULPI_VIEWPORT in your board configuration file. 1103 If your ULPI phy needs a different reference clock than the 1104 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to 1105 the appropriate value in Hz. 1106 1107- MMC Support: 1108 The MMC controller on the Intel PXA is supported. To 1109 enable this define CONFIG_MMC. The MMC can be 1110 accessed from the boot prompt by mapping the device 1111 to physical memory similar to flash. Command line is 1112 enabled with CONFIG_CMD_MMC. The MMC driver also works with 1113 the FAT fs. This is enabled with CONFIG_CMD_FAT. 1114 1115 CONFIG_SH_MMCIF 1116 Support for Renesas on-chip MMCIF controller 1117 1118 CONFIG_SH_MMCIF_ADDR 1119 Define the base address of MMCIF registers 1120 1121 CONFIG_SH_MMCIF_CLK 1122 Define the clock frequency for MMCIF 1123 1124 CONFIG_SUPPORT_EMMC_BOOT 1125 Enable some additional features of the eMMC boot partitions. 1126 1127- USB Device Firmware Update (DFU) class support: 1128 CONFIG_DFU_OVER_USB 1129 This enables the USB portion of the DFU USB class 1130 1131 CONFIG_DFU_NAND 1132 This enables support for exposing NAND devices via DFU. 1133 1134 CONFIG_DFU_RAM 1135 This enables support for exposing RAM via DFU. 1136 Note: DFU spec refer to non-volatile memory usage, but 1137 allow usages beyond the scope of spec - here RAM usage, 1138 one that would help mostly the developer. 1139 1140 CONFIG_SYS_DFU_DATA_BUF_SIZE 1141 Dfu transfer uses a buffer before writing data to the 1142 raw storage device. Make the size (in bytes) of this buffer 1143 configurable. The size of this buffer is also configurable 1144 through the "dfu_bufsiz" environment variable. 1145 1146 CONFIG_SYS_DFU_MAX_FILE_SIZE 1147 When updating files rather than the raw storage device, 1148 we use a static buffer to copy the file into and then write 1149 the buffer once we've been given the whole file. Define 1150 this to the maximum filesize (in bytes) for the buffer. 1151 Default is 4 MiB if undefined. 1152 1153 DFU_DEFAULT_POLL_TIMEOUT 1154 Poll timeout [ms], is the timeout a device can send to the 1155 host. The host must wait for this timeout before sending 1156 a subsequent DFU_GET_STATUS request to the device. 1157 1158 DFU_MANIFEST_POLL_TIMEOUT 1159 Poll timeout [ms], which the device sends to the host when 1160 entering dfuMANIFEST state. Host waits this timeout, before 1161 sending again an USB request to the device. 1162 1163- Journaling Flash filesystem support: 1164 CONFIG_JFFS2_NAND 1165 Define these for a default partition on a NAND device 1166 1167 CONFIG_SYS_JFFS2_FIRST_SECTOR, 1168 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS 1169 Define these for a default partition on a NOR device 1170 1171- Keyboard Support: 1172 See Kconfig help for available keyboard drivers. 1173 1174 CONFIG_KEYBOARD 1175 1176 Define this to enable a custom keyboard support. 1177 This simply calls drv_keyboard_init() which must be 1178 defined in your board-specific files. This option is deprecated 1179 and is only used by novena. For new boards, use driver model 1180 instead. 1181 1182- Video support: 1183 CONFIG_FSL_DIU_FB 1184 Enable the Freescale DIU video driver. Reference boards for 1185 SOCs that have a DIU should define this macro to enable DIU 1186 support, and should also define these other macros: 1187 1188 CONFIG_SYS_DIU_ADDR 1189 CONFIG_VIDEO 1190 CONFIG_CFB_CONSOLE 1191 CONFIG_VIDEO_SW_CURSOR 1192 CONFIG_VGA_AS_SINGLE_DEVICE 1193 CONFIG_VIDEO_LOGO 1194 CONFIG_VIDEO_BMP_LOGO 1195 1196 The DIU driver will look for the 'video-mode' environment 1197 variable, and if defined, enable the DIU as a console during 1198 boot. See the documentation file doc/README.video for a 1199 description of this variable. 1200 1201- LCD Support: CONFIG_LCD 1202 1203 Define this to enable LCD support (for output to LCD 1204 display); also select one of the supported displays 1205 by defining one of these: 1206 1207 CONFIG_ATMEL_LCD: 1208 1209 HITACHI TX09D70VM1CCA, 3.5", 240x320. 1210 1211 CONFIG_NEC_NL6448AC33: 1212 1213 NEC NL6448AC33-18. Active, color, single scan. 1214 1215 CONFIG_NEC_NL6448BC20 1216 1217 NEC NL6448BC20-08. 6.5", 640x480. 1218 Active, color, single scan. 1219 1220 CONFIG_NEC_NL6448BC33_54 1221 1222 NEC NL6448BC33-54. 10.4", 640x480. 1223 Active, color, single scan. 1224 1225 CONFIG_SHARP_16x9 1226 1227 Sharp 320x240. Active, color, single scan. 1228 It isn't 16x9, and I am not sure what it is. 1229 1230 CONFIG_SHARP_LQ64D341 1231 1232 Sharp LQ64D341 display, 640x480. 1233 Active, color, single scan. 1234 1235 CONFIG_HLD1045 1236 1237 HLD1045 display, 640x480. 1238 Active, color, single scan. 1239 1240 CONFIG_OPTREX_BW 1241 1242 Optrex CBL50840-2 NF-FW 99 22 M5 1243 or 1244 Hitachi LMG6912RPFC-00T 1245 or 1246 Hitachi SP14Q002 1247 1248 320x240. Black & white. 1249 1250 CONFIG_LCD_ALIGNMENT 1251 1252 Normally the LCD is page-aligned (typically 4KB). If this is 1253 defined then the LCD will be aligned to this value instead. 1254 For ARM it is sometimes useful to use MMU_SECTION_SIZE 1255 here, since it is cheaper to change data cache settings on 1256 a per-section basis. 1257 1258 1259 CONFIG_LCD_ROTATION 1260 1261 Sometimes, for example if the display is mounted in portrait 1262 mode or even if it's mounted landscape but rotated by 180degree, 1263 we need to rotate our content of the display relative to the 1264 framebuffer, so that user can read the messages which are 1265 printed out. 1266 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be 1267 initialized with a given rotation from "vl_rot" out of 1268 "vidinfo_t" which is provided by the board specific code. 1269 The value for vl_rot is coded as following (matching to 1270 fbcon=rotate:<n> linux-kernel commandline): 1271 0 = no rotation respectively 0 degree 1272 1 = 90 degree rotation 1273 2 = 180 degree rotation 1274 3 = 270 degree rotation 1275 1276 If CONFIG_LCD_ROTATION is not defined, the console will be 1277 initialized with 0degree rotation. 1278 1279 CONFIG_LCD_BMP_RLE8 1280 1281 Support drawing of RLE8-compressed bitmaps on the LCD. 1282 1283 CONFIG_I2C_EDID 1284 1285 Enables an 'i2c edid' command which can read EDID 1286 information over I2C from an attached LCD display. 1287 1288- Splash Screen Support: CONFIG_SPLASH_SCREEN 1289 1290 If this option is set, the environment is checked for 1291 a variable "splashimage". If found, the usual display 1292 of logo, copyright and system information on the LCD 1293 is suppressed and the BMP image at the address 1294 specified in "splashimage" is loaded instead. The 1295 console is redirected to the "nulldev", too. This 1296 allows for a "silent" boot where a splash screen is 1297 loaded very quickly after power-on. 1298 1299 CONFIG_SPLASHIMAGE_GUARD 1300 1301 If this option is set, then U-Boot will prevent the environment 1302 variable "splashimage" from being set to a problematic address 1303 (see doc/README.displaying-bmps). 1304 This option is useful for targets where, due to alignment 1305 restrictions, an improperly aligned BMP image will cause a data 1306 abort. If you think you will not have problems with unaligned 1307 accesses (for example because your toolchain prevents them) 1308 there is no need to set this option. 1309 1310 CONFIG_SPLASH_SCREEN_ALIGN 1311 1312 If this option is set the splash image can be freely positioned 1313 on the screen. Environment variable "splashpos" specifies the 1314 position as "x,y". If a positive number is given it is used as 1315 number of pixel from left/top. If a negative number is given it 1316 is used as number of pixel from right/bottom. You can also 1317 specify 'm' for centering the image. 1318 1319 Example: 1320 setenv splashpos m,m 1321 => image at center of screen 1322 1323 setenv splashpos 30,20 1324 => image at x = 30 and y = 20 1325 1326 setenv splashpos -10,m 1327 => vertically centered image 1328 at x = dspWidth - bmpWidth - 9 1329 1330- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP 1331 1332 If this option is set, additionally to standard BMP 1333 images, gzipped BMP images can be displayed via the 1334 splashscreen support or the bmp command. 1335 1336- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8 1337 1338 If this option is set, 8-bit RLE compressed BMP images 1339 can be displayed via the splashscreen support or the 1340 bmp command. 1341 1342- Compression support: 1343 CONFIG_GZIP 1344 1345 Enabled by default to support gzip compressed images. 1346 1347 CONFIG_BZIP2 1348 1349 If this option is set, support for bzip2 compressed 1350 images is included. If not, only uncompressed and gzip 1351 compressed images are supported. 1352 1353 NOTE: the bzip2 algorithm requires a lot of RAM, so 1354 the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should 1355 be at least 4MB. 1356 1357- MII/PHY support: 1358 CONFIG_PHY_CLOCK_FREQ (ppc4xx) 1359 1360 The clock frequency of the MII bus 1361 1362 CONFIG_PHY_RESET_DELAY 1363 1364 Some PHY like Intel LXT971A need extra delay after 1365 reset before any MII register access is possible. 1366 For such PHY, set this option to the usec delay 1367 required. (minimum 300usec for LXT971A) 1368 1369 CONFIG_PHY_CMD_DELAY (ppc4xx) 1370 1371 Some PHY like Intel LXT971A need extra delay after 1372 command issued before MII status register can be read 1373 1374- IP address: 1375 CONFIG_IPADDR 1376 1377 Define a default value for the IP address to use for 1378 the default Ethernet interface, in case this is not 1379 determined through e.g. bootp. 1380 (Environment variable "ipaddr") 1381 1382- Server IP address: 1383 CONFIG_SERVERIP 1384 1385 Defines a default value for the IP address of a TFTP 1386 server to contact when using the "tftboot" command. 1387 (Environment variable "serverip") 1388 1389 CONFIG_KEEP_SERVERADDR 1390 1391 Keeps the server's MAC address, in the env 'serveraddr' 1392 for passing to bootargs (like Linux's netconsole option) 1393 1394- Gateway IP address: 1395 CONFIG_GATEWAYIP 1396 1397 Defines a default value for the IP address of the 1398 default router where packets to other networks are 1399 sent to. 1400 (Environment variable "gatewayip") 1401 1402- Subnet mask: 1403 CONFIG_NETMASK 1404 1405 Defines a default value for the subnet mask (or 1406 routing prefix) which is used to determine if an IP 1407 address belongs to the local subnet or needs to be 1408 forwarded through a router. 1409 (Environment variable "netmask") 1410 1411- BOOTP Recovery Mode: 1412 CONFIG_BOOTP_RANDOM_DELAY 1413 1414 If you have many targets in a network that try to 1415 boot using BOOTP, you may want to avoid that all 1416 systems send out BOOTP requests at precisely the same 1417 moment (which would happen for instance at recovery 1418 from a power failure, when all systems will try to 1419 boot, thus flooding the BOOTP server. Defining 1420 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be 1421 inserted before sending out BOOTP requests. The 1422 following delays are inserted then: 1423 1424 1st BOOTP request: delay 0 ... 1 sec 1425 2nd BOOTP request: delay 0 ... 2 sec 1426 3rd BOOTP request: delay 0 ... 4 sec 1427 4th and following 1428 BOOTP requests: delay 0 ... 8 sec 1429 1430 CONFIG_BOOTP_ID_CACHE_SIZE 1431 1432 BOOTP packets are uniquely identified using a 32-bit ID. The 1433 server will copy the ID from client requests to responses and 1434 U-Boot will use this to determine if it is the destination of 1435 an incoming response. Some servers will check that addresses 1436 aren't in use before handing them out (usually using an ARP 1437 ping) and therefore take up to a few hundred milliseconds to 1438 respond. Network congestion may also influence the time it 1439 takes for a response to make it back to the client. If that 1440 time is too long, U-Boot will retransmit requests. In order 1441 to allow earlier responses to still be accepted after these 1442 retransmissions, U-Boot's BOOTP client keeps a small cache of 1443 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this 1444 cache. The default is to keep IDs for up to four outstanding 1445 requests. Increasing this will allow U-Boot to accept offers 1446 from a BOOTP client in networks with unusually high latency. 1447 1448- DHCP Advanced Options: 1449 You can fine tune the DHCP functionality by defining 1450 CONFIG_BOOTP_* symbols: 1451 1452 CONFIG_BOOTP_NISDOMAIN 1453 CONFIG_BOOTP_BOOTFILESIZE 1454 CONFIG_BOOTP_SEND_HOSTNAME 1455 CONFIG_BOOTP_NTPSERVER 1456 CONFIG_BOOTP_TIMEOFFSET 1457 CONFIG_BOOTP_VENDOREX 1458 CONFIG_BOOTP_MAY_FAIL 1459 1460 CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip 1461 environment variable, not the BOOTP server. 1462 1463 CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found 1464 after the configured retry count, the call will fail 1465 instead of starting over. This can be used to fail over 1466 to Link-local IP address configuration if the DHCP server 1467 is not available. 1468 1469 CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable 1470 to do a dynamic update of a DNS server. To do this, they 1471 need the hostname of the DHCP requester. 1472 If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content 1473 of the "hostname" environment variable is passed as 1474 option 12 to the DHCP server. 1475 1476 CONFIG_BOOTP_DHCP_REQUEST_DELAY 1477 1478 A 32bit value in microseconds for a delay between 1479 receiving a "DHCP Offer" and sending the "DHCP Request". 1480 This fixes a problem with certain DHCP servers that don't 1481 respond 100% of the time to a "DHCP request". E.g. On an 1482 AT91RM9200 processor running at 180MHz, this delay needed 1483 to be *at least* 15,000 usec before a Windows Server 2003 1484 DHCP server would reply 100% of the time. I recommend at 1485 least 50,000 usec to be safe. The alternative is to hope 1486 that one of the retries will be successful but note that 1487 the DHCP timeout and retry process takes a longer than 1488 this delay. 1489 1490 - Link-local IP address negotiation: 1491 Negotiate with other link-local clients on the local network 1492 for an address that doesn't require explicit configuration. 1493 This is especially useful if a DHCP server cannot be guaranteed 1494 to exist in all environments that the device must operate. 1495 1496 See doc/README.link-local for more information. 1497 1498 - MAC address from environment variables 1499 1500 FDT_SEQ_MACADDR_FROM_ENV 1501 1502 Fix-up device tree with MAC addresses fetched sequentially from 1503 environment variables. This config work on assumption that 1504 non-usable ethernet node of device-tree are either not present 1505 or their status has been marked as "disabled". 1506 1507 - CDP Options: 1508 CONFIG_CDP_DEVICE_ID 1509 1510 The device id used in CDP trigger frames. 1511 1512 CONFIG_CDP_DEVICE_ID_PREFIX 1513 1514 A two character string which is prefixed to the MAC address 1515 of the device. 1516 1517 CONFIG_CDP_PORT_ID 1518 1519 A printf format string which contains the ascii name of 1520 the port. Normally is set to "eth%d" which sets 1521 eth0 for the first Ethernet, eth1 for the second etc. 1522 1523 CONFIG_CDP_CAPABILITIES 1524 1525 A 32bit integer which indicates the device capabilities; 1526 0x00000010 for a normal host which does not forwards. 1527 1528 CONFIG_CDP_VERSION 1529 1530 An ascii string containing the version of the software. 1531 1532 CONFIG_CDP_PLATFORM 1533 1534 An ascii string containing the name of the platform. 1535 1536 CONFIG_CDP_TRIGGER 1537 1538 A 32bit integer sent on the trigger. 1539 1540 CONFIG_CDP_POWER_CONSUMPTION 1541 1542 A 16bit integer containing the power consumption of the 1543 device in .1 of milliwatts. 1544 1545 CONFIG_CDP_APPLIANCE_VLAN_TYPE 1546 1547 A byte containing the id of the VLAN. 1548 1549- Status LED: CONFIG_LED_STATUS 1550 1551 Several configurations allow to display the current 1552 status using a LED. For instance, the LED will blink 1553 fast while running U-Boot code, stop blinking as 1554 soon as a reply to a BOOTP request was received, and 1555 start blinking slow once the Linux kernel is running 1556 (supported by a status LED driver in the Linux 1557 kernel). Defining CONFIG_LED_STATUS enables this 1558 feature in U-Boot. 1559 1560 Additional options: 1561 1562 CONFIG_LED_STATUS_GPIO 1563 The status LED can be connected to a GPIO pin. 1564 In such cases, the gpio_led driver can be used as a 1565 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO 1566 to include the gpio_led driver in the U-Boot binary. 1567 1568 CONFIG_GPIO_LED_INVERTED_TABLE 1569 Some GPIO connected LEDs may have inverted polarity in which 1570 case the GPIO high value corresponds to LED off state and 1571 GPIO low value corresponds to LED on state. 1572 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined 1573 with a list of GPIO LEDs that have inverted polarity. 1574 1575- I2C Support: CONFIG_SYS_I2C 1576 1577 This enable the NEW i2c subsystem, and will allow you to use 1578 i2c commands at the u-boot command line (as long as you set 1579 CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c 1580 based realtime clock chips or other i2c devices. See 1581 common/cmd_i2c.c for a description of the command line 1582 interface. 1583 1584 ported i2c driver to the new framework: 1585 - drivers/i2c/soft_i2c.c: 1586 - activate first bus with CONFIG_SYS_I2C_SOFT define 1587 CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE 1588 for defining speed and slave address 1589 - activate second bus with I2C_SOFT_DECLARATIONS2 define 1590 CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2 1591 for defining speed and slave address 1592 - activate third bus with I2C_SOFT_DECLARATIONS3 define 1593 CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3 1594 for defining speed and slave address 1595 - activate fourth bus with I2C_SOFT_DECLARATIONS4 define 1596 CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4 1597 for defining speed and slave address 1598 1599 - drivers/i2c/fsl_i2c.c: 1600 - activate i2c driver with CONFIG_SYS_I2C_FSL 1601 define CONFIG_SYS_FSL_I2C_OFFSET for setting the register 1602 offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and 1603 CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first 1604 bus. 1605 - If your board supports a second fsl i2c bus, define 1606 CONFIG_SYS_FSL_I2C2_OFFSET for the register offset 1607 CONFIG_SYS_FSL_I2C2_SPEED for the speed and 1608 CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the 1609 second bus. 1610 1611 - drivers/i2c/tegra_i2c.c: 1612 - activate this driver with CONFIG_SYS_I2C_TEGRA 1613 - This driver adds 4 i2c buses with a fix speed from 1614 100000 and the slave addr 0! 1615 1616 - drivers/i2c/ppc4xx_i2c.c 1617 - activate this driver with CONFIG_SYS_I2C_PPC4XX 1618 - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0 1619 - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1 1620 1621 - drivers/i2c/i2c_mxc.c 1622 - activate this driver with CONFIG_SYS_I2C_MXC 1623 - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1 1624 - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2 1625 - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3 1626 - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4 1627 - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED 1628 - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE 1629 - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED 1630 - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE 1631 - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED 1632 - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE 1633 - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED 1634 - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE 1635 If those defines are not set, default value is 100000 1636 for speed, and 0 for slave. 1637 1638 - drivers/i2c/rcar_i2c.c: 1639 - activate this driver with CONFIG_SYS_I2C_RCAR 1640 - This driver adds 4 i2c buses 1641 1642 - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0 1643 - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0 1644 - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1 1645 - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1 1646 - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2 1647 - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2 1648 - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3 1649 - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3 1650 - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses 1651 1652 - drivers/i2c/sh_i2c.c: 1653 - activate this driver with CONFIG_SYS_I2C_SH 1654 - This driver adds from 2 to 5 i2c buses 1655 1656 - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0 1657 - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0 1658 - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1 1659 - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1 1660 - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2 1661 - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2 1662 - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3 1663 - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3 1664 - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4 1665 - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4 1666 - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses 1667 1668 - drivers/i2c/omap24xx_i2c.c 1669 - activate this driver with CONFIG_SYS_I2C_OMAP24XX 1670 - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0 1671 - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0 1672 - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1 1673 - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1 1674 - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2 1675 - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2 1676 - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3 1677 - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3 1678 - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4 1679 - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4 1680 1681 - drivers/i2c/s3c24x0_i2c.c: 1682 - activate this driver with CONFIG_SYS_I2C_S3C24X0 1683 - This driver adds i2c buses (11 for Exynos5250, Exynos5420 1684 9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung) 1685 with a fix speed from 100000 and the slave addr 0! 1686 1687 - drivers/i2c/ihs_i2c.c 1688 - activate this driver with CONFIG_SYS_I2C_IHS 1689 - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0 1690 - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0 1691 - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0 1692 - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1 1693 - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1 1694 - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1 1695 - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2 1696 - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2 1697 - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2 1698 - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3 1699 - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3 1700 - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3 1701 - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL 1702 - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1 1703 - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1 1704 - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1 1705 - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1 1706 - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1 1707 - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1 1708 - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1 1709 - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1 1710 1711 additional defines: 1712 1713 CONFIG_SYS_NUM_I2C_BUSES 1714 Hold the number of i2c buses you want to use. 1715 1716 CONFIG_SYS_I2C_DIRECT_BUS 1717 define this, if you don't use i2c muxes on your hardware. 1718 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can 1719 omit this define. 1720 1721 CONFIG_SYS_I2C_MAX_HOPS 1722 define how many muxes are maximal consecutively connected 1723 on one i2c bus. If you not use i2c muxes, omit this 1724 define. 1725 1726 CONFIG_SYS_I2C_BUSES 1727 hold a list of buses you want to use, only used if 1728 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example 1729 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and 1730 CONFIG_SYS_NUM_I2C_BUSES = 9: 1731 1732 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \ 1733 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \ 1734 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \ 1735 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \ 1736 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \ 1737 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \ 1738 {1, {I2C_NULL_HOP}}, \ 1739 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \ 1740 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \ 1741 } 1742 1743 which defines 1744 bus 0 on adapter 0 without a mux 1745 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1 1746 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2 1747 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3 1748 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4 1749 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5 1750 bus 6 on adapter 1 without a mux 1751 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1 1752 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2 1753 1754 If you do not have i2c muxes on your board, omit this define. 1755 1756- Legacy I2C Support: 1757 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT) 1758 then the following macros need to be defined (examples are 1759 from include/configs/lwmon.h): 1760 1761 I2C_INIT 1762 1763 (Optional). Any commands necessary to enable the I2C 1764 controller or configure ports. 1765 1766 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL) 1767 1768 I2C_ACTIVE 1769 1770 The code necessary to make the I2C data line active 1771 (driven). If the data line is open collector, this 1772 define can be null. 1773 1774 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA) 1775 1776 I2C_TRISTATE 1777 1778 The code necessary to make the I2C data line tri-stated 1779 (inactive). If the data line is open collector, this 1780 define can be null. 1781 1782 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA) 1783 1784 I2C_READ 1785 1786 Code that returns true if the I2C data line is high, 1787 false if it is low. 1788 1789 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0) 1790 1791 I2C_SDA(bit) 1792 1793 If <bit> is true, sets the I2C data line high. If it 1794 is false, it clears it (low). 1795 1796 eg: #define I2C_SDA(bit) \ 1797 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \ 1798 else immr->im_cpm.cp_pbdat &= ~PB_SDA 1799 1800 I2C_SCL(bit) 1801 1802 If <bit> is true, sets the I2C clock line high. If it 1803 is false, it clears it (low). 1804 1805 eg: #define I2C_SCL(bit) \ 1806 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \ 1807 else immr->im_cpm.cp_pbdat &= ~PB_SCL 1808 1809 I2C_DELAY 1810 1811 This delay is invoked four times per clock cycle so this 1812 controls the rate of data transfer. The data rate thus 1813 is 1 / (I2C_DELAY * 4). Often defined to be something 1814 like: 1815 1816 #define I2C_DELAY udelay(2) 1817 1818 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA 1819 1820 If your arch supports the generic GPIO framework (asm/gpio.h), 1821 then you may alternatively define the two GPIOs that are to be 1822 used as SCL / SDA. Any of the previous I2C_xxx macros will 1823 have GPIO-based defaults assigned to them as appropriate. 1824 1825 You should define these to the GPIO value as given directly to 1826 the generic GPIO functions. 1827 1828 CONFIG_SYS_I2C_INIT_BOARD 1829 1830 When a board is reset during an i2c bus transfer 1831 chips might think that the current transfer is still 1832 in progress. On some boards it is possible to access 1833 the i2c SCLK line directly, either by using the 1834 processor pin as a GPIO or by having a second pin 1835 connected to the bus. If this option is defined a 1836 custom i2c_init_board() routine in boards/xxx/board.c 1837 is run early in the boot sequence. 1838 1839 CONFIG_I2C_MULTI_BUS 1840 1841 This option allows the use of multiple I2C buses, each of which 1842 must have a controller. At any point in time, only one bus is 1843 active. To switch to a different bus, use the 'i2c dev' command. 1844 Note that bus numbering is zero-based. 1845 1846 CONFIG_SYS_I2C_NOPROBES 1847 1848 This option specifies a list of I2C devices that will be skipped 1849 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS 1850 is set, specify a list of bus-device pairs. Otherwise, specify 1851 a 1D array of device addresses 1852 1853 e.g. 1854 #undef CONFIG_I2C_MULTI_BUS 1855 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68} 1856 1857 will skip addresses 0x50 and 0x68 on a board with one I2C bus 1858 1859 #define CONFIG_I2C_MULTI_BUS 1860 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}} 1861 1862 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1 1863 1864 CONFIG_SYS_SPD_BUS_NUM 1865 1866 If defined, then this indicates the I2C bus number for DDR SPD. 1867 If not defined, then U-Boot assumes that SPD is on I2C bus 0. 1868 1869 CONFIG_SYS_RTC_BUS_NUM 1870 1871 If defined, then this indicates the I2C bus number for the RTC. 1872 If not defined, then U-Boot assumes that RTC is on I2C bus 0. 1873 1874 CONFIG_SOFT_I2C_READ_REPEATED_START 1875 1876 defining this will force the i2c_read() function in 1877 the soft_i2c driver to perform an I2C repeated start 1878 between writing the address pointer and reading the 1879 data. If this define is omitted the default behaviour 1880 of doing a stop-start sequence will be used. Most I2C 1881 devices can use either method, but some require one or 1882 the other. 1883 1884- SPI Support: CONFIG_SPI 1885 1886 Enables SPI driver (so far only tested with 1887 SPI EEPROM, also an instance works with Crystal A/D and 1888 D/As on the SACSng board) 1889 1890 CONFIG_SOFT_SPI 1891 1892 Enables a software (bit-bang) SPI driver rather than 1893 using hardware support. This is a general purpose 1894 driver that only requires three general I/O port pins 1895 (two outputs, one input) to function. If this is 1896 defined, the board configuration must define several 1897 SPI configuration items (port pins to use, etc). For 1898 an example, see include/configs/sacsng.h. 1899 1900 CONFIG_SYS_SPI_MXC_WAIT 1901 Timeout for waiting until spi transfer completed. 1902 default: (CONFIG_SYS_HZ/100) /* 10 ms */ 1903 1904- FPGA Support: CONFIG_FPGA 1905 1906 Enables FPGA subsystem. 1907 1908 CONFIG_FPGA_<vendor> 1909 1910 Enables support for specific chip vendors. 1911 (ALTERA, XILINX) 1912 1913 CONFIG_FPGA_<family> 1914 1915 Enables support for FPGA family. 1916 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX) 1917 1918 CONFIG_FPGA_COUNT 1919 1920 Specify the number of FPGA devices to support. 1921 1922 CONFIG_SYS_FPGA_PROG_FEEDBACK 1923 1924 Enable printing of hash marks during FPGA configuration. 1925 1926 CONFIG_SYS_FPGA_CHECK_BUSY 1927 1928 Enable checks on FPGA configuration interface busy 1929 status by the configuration function. This option 1930 will require a board or device specific function to 1931 be written. 1932 1933 CONFIG_FPGA_DELAY 1934 1935 If defined, a function that provides delays in the FPGA 1936 configuration driver. 1937 1938 CONFIG_SYS_FPGA_CHECK_CTRLC 1939 Allow Control-C to interrupt FPGA configuration 1940 1941 CONFIG_SYS_FPGA_CHECK_ERROR 1942 1943 Check for configuration errors during FPGA bitfile 1944 loading. For example, abort during Virtex II 1945 configuration if the INIT_B line goes low (which 1946 indicated a CRC error). 1947 1948 CONFIG_SYS_FPGA_WAIT_INIT 1949 1950 Maximum time to wait for the INIT_B line to de-assert 1951 after PROB_B has been de-asserted during a Virtex II 1952 FPGA configuration sequence. The default time is 500 1953 ms. 1954 1955 CONFIG_SYS_FPGA_WAIT_BUSY 1956 1957 Maximum time to wait for BUSY to de-assert during 1958 Virtex II FPGA configuration. The default is 5 ms. 1959 1960 CONFIG_SYS_FPGA_WAIT_CONFIG 1961 1962 Time to wait after FPGA configuration. The default is 1963 200 ms. 1964 1965- Configuration Management: 1966 1967 CONFIG_IDENT_STRING 1968 1969 If defined, this string will be added to the U-Boot 1970 version information (U_BOOT_VERSION) 1971 1972- Vendor Parameter Protection: 1973 1974 U-Boot considers the values of the environment 1975 variables "serial#" (Board Serial Number) and 1976 "ethaddr" (Ethernet Address) to be parameters that 1977 are set once by the board vendor / manufacturer, and 1978 protects these variables from casual modification by 1979 the user. Once set, these variables are read-only, 1980 and write or delete attempts are rejected. You can 1981 change this behaviour: 1982 1983 If CONFIG_ENV_OVERWRITE is #defined in your config 1984 file, the write protection for vendor parameters is 1985 completely disabled. Anybody can change or delete 1986 these parameters. 1987 1988 Alternatively, if you define _both_ an ethaddr in the 1989 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default 1990 Ethernet address is installed in the environment, 1991 which can be changed exactly ONCE by the user. [The 1992 serial# is unaffected by this, i. e. it remains 1993 read-only.] 1994 1995 The same can be accomplished in a more flexible way 1996 for any variable by configuring the type of access 1997 to allow for those variables in the ".flags" variable 1998 or define CONFIG_ENV_FLAGS_LIST_STATIC. 1999 2000- Protected RAM: 2001 CONFIG_PRAM 2002 2003 Define this variable to enable the reservation of 2004 "protected RAM", i. e. RAM which is not overwritten 2005 by U-Boot. Define CONFIG_PRAM to hold the number of 2006 kB you want to reserve for pRAM. You can overwrite 2007 this default value by defining an environment 2008 variable "pram" to the number of kB you want to 2009 reserve. Note that the board info structure will 2010 still show the full amount of RAM. If pRAM is 2011 reserved, a new environment variable "mem" will 2012 automatically be defined to hold the amount of 2013 remaining RAM in a form that can be passed as boot 2014 argument to Linux, for instance like that: 2015 2016 setenv bootargs ... mem=\${mem} 2017 saveenv 2018 2019 This way you can tell Linux not to use this memory, 2020 either, which results in a memory region that will 2021 not be affected by reboots. 2022 2023 *WARNING* If your board configuration uses automatic 2024 detection of the RAM size, you must make sure that 2025 this memory test is non-destructive. So far, the 2026 following board configurations are known to be 2027 "pRAM-clean": 2028 2029 IVMS8, IVML24, SPD8xx, 2030 HERMES, IP860, RPXlite, LWMON, 2031 FLAGADM 2032 2033- Access to physical memory region (> 4GB) 2034 Some basic support is provided for operations on memory not 2035 normally accessible to U-Boot - e.g. some architectures 2036 support access to more than 4GB of memory on 32-bit 2037 machines using physical address extension or similar. 2038 Define CONFIG_PHYSMEM to access this basic support, which 2039 currently only supports clearing the memory. 2040 2041- Error Recovery: 2042 CONFIG_NET_RETRY_COUNT 2043 2044 This variable defines the number of retries for 2045 network operations like ARP, RARP, TFTP, or BOOTP 2046 before giving up the operation. If not defined, a 2047 default value of 5 is used. 2048 2049 CONFIG_ARP_TIMEOUT 2050 2051 Timeout waiting for an ARP reply in milliseconds. 2052 2053 CONFIG_NFS_TIMEOUT 2054 2055 Timeout in milliseconds used in NFS protocol. 2056 If you encounter "ERROR: Cannot umount" in nfs command, 2057 try longer timeout such as 2058 #define CONFIG_NFS_TIMEOUT 10000UL 2059 2060- Command Interpreter: 2061 CONFIG_SYS_PROMPT_HUSH_PS2 2062 2063 This defines the secondary prompt string, which is 2064 printed when the command interpreter needs more input 2065 to complete a command. Usually "> ". 2066 2067 Note: 2068 2069 In the current implementation, the local variables 2070 space and global environment variables space are 2071 separated. Local variables are those you define by 2072 simply typing `name=value'. To access a local 2073 variable later on, you have write `$name' or 2074 `${name}'; to execute the contents of a variable 2075 directly type `$name' at the command prompt. 2076 2077 Global environment variables are those you use 2078 setenv/printenv to work with. To run a command stored 2079 in such a variable, you need to use the run command, 2080 and you must not use the '$' sign to access them. 2081 2082 To store commands and special characters in a 2083 variable, please use double quotation marks 2084 surrounding the whole text of the variable, instead 2085 of the backslashes before semicolons and special 2086 symbols. 2087 2088- Command Line Editing and History: 2089 CONFIG_CMDLINE_PS_SUPPORT 2090 2091 Enable support for changing the command prompt string 2092 at run-time. Only static string is supported so far. 2093 The string is obtained from environment variables PS1 2094 and PS2. 2095 2096- Default Environment: 2097 CONFIG_EXTRA_ENV_SETTINGS 2098 2099 Define this to contain any number of null terminated 2100 strings (variable = value pairs) that will be part of 2101 the default environment compiled into the boot image. 2102 2103 For example, place something like this in your 2104 board's config file: 2105 2106 #define CONFIG_EXTRA_ENV_SETTINGS \ 2107 "myvar1=value1\0" \ 2108 "myvar2=value2\0" 2109 2110 Warning: This method is based on knowledge about the 2111 internal format how the environment is stored by the 2112 U-Boot code. This is NOT an official, exported 2113 interface! Although it is unlikely that this format 2114 will change soon, there is no guarantee either. 2115 You better know what you are doing here. 2116 2117 Note: overly (ab)use of the default environment is 2118 discouraged. Make sure to check other ways to preset 2119 the environment like the "source" command or the 2120 boot command first. 2121 2122 CONFIG_DELAY_ENVIRONMENT 2123 2124 Normally the environment is loaded when the board is 2125 initialised so that it is available to U-Boot. This inhibits 2126 that so that the environment is not available until 2127 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL 2128 this is instead controlled by the value of 2129 /config/load-environment. 2130 2131- TFTP Fixed UDP Port: 2132 CONFIG_TFTP_PORT 2133 2134 If this is defined, the environment variable tftpsrcp 2135 is used to supply the TFTP UDP source port value. 2136 If tftpsrcp isn't defined, the normal pseudo-random port 2137 number generator is used. 2138 2139 Also, the environment variable tftpdstp is used to supply 2140 the TFTP UDP destination port value. If tftpdstp isn't 2141 defined, the normal port 69 is used. 2142 2143 The purpose for tftpsrcp is to allow a TFTP server to 2144 blindly start the TFTP transfer using the pre-configured 2145 target IP address and UDP port. This has the effect of 2146 "punching through" the (Windows XP) firewall, allowing 2147 the remainder of the TFTP transfer to proceed normally. 2148 A better solution is to properly configure the firewall, 2149 but sometimes that is not allowed. 2150 2151- Show boot progress: 2152 CONFIG_SHOW_BOOT_PROGRESS 2153 2154 Defining this option allows to add some board- 2155 specific code (calling a user-provided function 2156 "show_boot_progress(int)") that enables you to show 2157 the system's boot progress on some display (for 2158 example, some LED's) on your board. At the moment, 2159 the following checkpoints are implemented: 2160 2161 2162Legacy uImage format: 2163 2164 Arg Where When 2165 1 common/cmd_bootm.c before attempting to boot an image 2166 -1 common/cmd_bootm.c Image header has bad magic number 2167 2 common/cmd_bootm.c Image header has correct magic number 2168 -2 common/cmd_bootm.c Image header has bad checksum 2169 3 common/cmd_bootm.c Image header has correct checksum 2170 -3 common/cmd_bootm.c Image data has bad checksum 2171 4 common/cmd_bootm.c Image data has correct checksum 2172 -4 common/cmd_bootm.c Image is for unsupported architecture 2173 5 common/cmd_bootm.c Architecture check OK 2174 -5 common/cmd_bootm.c Wrong Image Type (not kernel, multi) 2175 6 common/cmd_bootm.c Image Type check OK 2176 -6 common/cmd_bootm.c gunzip uncompression error 2177 -7 common/cmd_bootm.c Unimplemented compression type 2178 7 common/cmd_bootm.c Uncompression OK 2179 8 common/cmd_bootm.c No uncompress/copy overwrite error 2180 -9 common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX) 2181 2182 9 common/image.c Start initial ramdisk verification 2183 -10 common/image.c Ramdisk header has bad magic number 2184 -11 common/image.c Ramdisk header has bad checksum 2185 10 common/image.c Ramdisk header is OK 2186 -12 common/image.c Ramdisk data has bad checksum 2187 11 common/image.c Ramdisk data has correct checksum 2188 12 common/image.c Ramdisk verification complete, start loading 2189 -13 common/image.c Wrong Image Type (not PPC Linux ramdisk) 2190 13 common/image.c Start multifile image verification 2191 14 common/image.c No initial ramdisk, no multifile, continue. 2192 2193 15 arch/<arch>/lib/bootm.c All preparation done, transferring control to OS 2194 2195 -30 arch/powerpc/lib/board.c Fatal error, hang the system 2196 -31 post/post.c POST test failed, detected by post_output_backlog() 2197 -32 post/post.c POST test failed, detected by post_run_single() 2198 2199 34 common/cmd_doc.c before loading a Image from a DOC device 2200 -35 common/cmd_doc.c Bad usage of "doc" command 2201 35 common/cmd_doc.c correct usage of "doc" command 2202 -36 common/cmd_doc.c No boot device 2203 36 common/cmd_doc.c correct boot device 2204 -37 common/cmd_doc.c Unknown Chip ID on boot device 2205 37 common/cmd_doc.c correct chip ID found, device available 2206 -38 common/cmd_doc.c Read Error on boot device 2207 38 common/cmd_doc.c reading Image header from DOC device OK 2208 -39 common/cmd_doc.c Image header has bad magic number 2209 39 common/cmd_doc.c Image header has correct magic number 2210 -40 common/cmd_doc.c Error reading Image from DOC device 2211 40 common/cmd_doc.c Image header has correct magic number 2212 41 common/cmd_ide.c before loading a Image from a IDE device 2213 -42 common/cmd_ide.c Bad usage of "ide" command 2214 42 common/cmd_ide.c correct usage of "ide" command 2215 -43 common/cmd_ide.c No boot device 2216 43 common/cmd_ide.c boot device found 2217 -44 common/cmd_ide.c Device not available 2218 44 common/cmd_ide.c Device available 2219 -45 common/cmd_ide.c wrong partition selected 2220 45 common/cmd_ide.c partition selected 2221 -46 common/cmd_ide.c Unknown partition table 2222 46 common/cmd_ide.c valid partition table found 2223 -47 common/cmd_ide.c Invalid partition type 2224 47 common/cmd_ide.c correct partition type 2225 -48 common/cmd_ide.c Error reading Image Header on boot device 2226 48 common/cmd_ide.c reading Image Header from IDE device OK 2227 -49 common/cmd_ide.c Image header has bad magic number 2228 49 common/cmd_ide.c Image header has correct magic number 2229 -50 common/cmd_ide.c Image header has bad checksum 2230 50 common/cmd_ide.c Image header has correct checksum 2231 -51 common/cmd_ide.c Error reading Image from IDE device 2232 51 common/cmd_ide.c reading Image from IDE device OK 2233 52 common/cmd_nand.c before loading a Image from a NAND device 2234 -53 common/cmd_nand.c Bad usage of "nand" command 2235 53 common/cmd_nand.c correct usage of "nand" command 2236 -54 common/cmd_nand.c No boot device 2237 54 common/cmd_nand.c boot device found 2238 -55 common/cmd_nand.c Unknown Chip ID on boot device 2239 55 common/cmd_nand.c correct chip ID found, device available 2240 -56 common/cmd_nand.c Error reading Image Header on boot device 2241 56 common/cmd_nand.c reading Image Header from NAND device OK 2242 -57 common/cmd_nand.c Image header has bad magic number 2243 57 common/cmd_nand.c Image header has correct magic number 2244 -58 common/cmd_nand.c Error reading Image from NAND device 2245 58 common/cmd_nand.c reading Image from NAND device OK 2246 2247 -60 common/env_common.c Environment has a bad CRC, using default 2248 2249 64 net/eth.c starting with Ethernet configuration. 2250 -64 net/eth.c no Ethernet found. 2251 65 net/eth.c Ethernet found. 2252 2253 -80 common/cmd_net.c usage wrong 2254 80 common/cmd_net.c before calling net_loop() 2255 -81 common/cmd_net.c some error in net_loop() occurred 2256 81 common/cmd_net.c net_loop() back without error 2257 -82 common/cmd_net.c size == 0 (File with size 0 loaded) 2258 82 common/cmd_net.c trying automatic boot 2259 83 common/cmd_net.c running "source" command 2260 -83 common/cmd_net.c some error in automatic boot or "source" command 2261 84 common/cmd_net.c end without errors 2262 2263FIT uImage format: 2264 2265 Arg Where When 2266 100 common/cmd_bootm.c Kernel FIT Image has correct format 2267 -100 common/cmd_bootm.c Kernel FIT Image has incorrect format 2268 101 common/cmd_bootm.c No Kernel subimage unit name, using configuration 2269 -101 common/cmd_bootm.c Can't get configuration for kernel subimage 2270 102 common/cmd_bootm.c Kernel unit name specified 2271 -103 common/cmd_bootm.c Can't get kernel subimage node offset 2272 103 common/cmd_bootm.c Found configuration node 2273 104 common/cmd_bootm.c Got kernel subimage node offset 2274 -104 common/cmd_bootm.c Kernel subimage hash verification failed 2275 105 common/cmd_bootm.c Kernel subimage hash verification OK 2276 -105 common/cmd_bootm.c Kernel subimage is for unsupported architecture 2277 106 common/cmd_bootm.c Architecture check OK 2278 -106 common/cmd_bootm.c Kernel subimage has wrong type 2279 107 common/cmd_bootm.c Kernel subimage type OK 2280 -107 common/cmd_bootm.c Can't get kernel subimage data/size 2281 108 common/cmd_bootm.c Got kernel subimage data/size 2282 -108 common/cmd_bootm.c Wrong image type (not legacy, FIT) 2283 -109 common/cmd_bootm.c Can't get kernel subimage type 2284 -110 common/cmd_bootm.c Can't get kernel subimage comp 2285 -111 common/cmd_bootm.c Can't get kernel subimage os 2286 -112 common/cmd_bootm.c Can't get kernel subimage load address 2287 -113 common/cmd_bootm.c Image uncompress/copy overwrite error 2288 2289 120 common/image.c Start initial ramdisk verification 2290 -120 common/image.c Ramdisk FIT image has incorrect format 2291 121 common/image.c Ramdisk FIT image has correct format 2292 122 common/image.c No ramdisk subimage unit name, using configuration 2293 -122 common/image.c Can't get configuration for ramdisk subimage 2294 123 common/image.c Ramdisk unit name specified 2295 -124 common/image.c Can't get ramdisk subimage node offset 2296 125 common/image.c Got ramdisk subimage node offset 2297 -125 common/image.c Ramdisk subimage hash verification failed 2298 126 common/image.c Ramdisk subimage hash verification OK 2299 -126 common/image.c Ramdisk subimage for unsupported architecture 2300 127 common/image.c Architecture check OK 2301 -127 common/image.c Can't get ramdisk subimage data/size 2302 128 common/image.c Got ramdisk subimage data/size 2303 129 common/image.c Can't get ramdisk load address 2304 -129 common/image.c Got ramdisk load address 2305 2306 -130 common/cmd_doc.c Incorrect FIT image format 2307 131 common/cmd_doc.c FIT image format OK 2308 2309 -140 common/cmd_ide.c Incorrect FIT image format 2310 141 common/cmd_ide.c FIT image format OK 2311 2312 -150 common/cmd_nand.c Incorrect FIT image format 2313 151 common/cmd_nand.c FIT image format OK 2314 2315- Standalone program support: 2316 CONFIG_STANDALONE_LOAD_ADDR 2317 2318 This option defines a board specific value for the 2319 address where standalone program gets loaded, thus 2320 overwriting the architecture dependent default 2321 settings. 2322 2323- Frame Buffer Address: 2324 CONFIG_FB_ADDR 2325 2326 Define CONFIG_FB_ADDR if you want to use specific 2327 address for frame buffer. This is typically the case 2328 when using a graphics controller has separate video 2329 memory. U-Boot will then place the frame buffer at 2330 the given address instead of dynamically reserving it 2331 in system RAM by calling lcd_setmem(), which grabs 2332 the memory for the frame buffer depending on the 2333 configured panel size. 2334 2335 Please see board_init_f function. 2336 2337- Automatic software updates via TFTP server 2338 CONFIG_UPDATE_TFTP 2339 CONFIG_UPDATE_TFTP_CNT_MAX 2340 CONFIG_UPDATE_TFTP_MSEC_MAX 2341 2342 These options enable and control the auto-update feature; 2343 for a more detailed description refer to doc/README.update. 2344 2345- MTD Support (mtdparts command, UBI support) 2346 CONFIG_MTD_UBI_WL_THRESHOLD 2347 This parameter defines the maximum difference between the highest 2348 erase counter value and the lowest erase counter value of eraseblocks 2349 of UBI devices. When this threshold is exceeded, UBI starts performing 2350 wear leveling by means of moving data from eraseblock with low erase 2351 counter to eraseblocks with high erase counter. 2352 2353 The default value should be OK for SLC NAND flashes, NOR flashes and 2354 other flashes which have eraseblock life-cycle 100000 or more. 2355 However, in case of MLC NAND flashes which typically have eraseblock 2356 life-cycle less than 10000, the threshold should be lessened (e.g., 2357 to 128 or 256, although it does not have to be power of 2). 2358 2359 default: 4096 2360 2361 CONFIG_MTD_UBI_BEB_LIMIT 2362 This option specifies the maximum bad physical eraseblocks UBI 2363 expects on the MTD device (per 1024 eraseblocks). If the 2364 underlying flash does not admit of bad eraseblocks (e.g. NOR 2365 flash), this value is ignored. 2366 2367 NAND datasheets often specify the minimum and maximum NVM 2368 (Number of Valid Blocks) for the flashes' endurance lifetime. 2369 The maximum expected bad eraseblocks per 1024 eraseblocks 2370 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)", 2371 which gives 20 for most NANDs (MaxNVB is basically the total 2372 count of eraseblocks on the chip). 2373 2374 To put it differently, if this value is 20, UBI will try to 2375 reserve about 1.9% of physical eraseblocks for bad blocks 2376 handling. And that will be 1.9% of eraseblocks on the entire 2377 NAND chip, not just the MTD partition UBI attaches. This means 2378 that if you have, say, a NAND flash chip admits maximum 40 bad 2379 eraseblocks, and it is split on two MTD partitions of the same 2380 size, UBI will reserve 40 eraseblocks when attaching a 2381 partition. 2382 2383 default: 20 2384 2385 CONFIG_MTD_UBI_FASTMAP 2386 Fastmap is a mechanism which allows attaching an UBI device 2387 in nearly constant time. Instead of scanning the whole MTD device it 2388 only has to locate a checkpoint (called fastmap) on the device. 2389 The on-flash fastmap contains all information needed to attach 2390 the device. Using fastmap makes only sense on large devices where 2391 attaching by scanning takes long. UBI will not automatically install 2392 a fastmap on old images, but you can set the UBI parameter 2393 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note 2394 that fastmap-enabled images are still usable with UBI implementations 2395 without fastmap support. On typical flash devices the whole fastmap 2396 fits into one PEB. UBI will reserve PEBs to hold two fastmaps. 2397 2398 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT 2399 Set this parameter to enable fastmap automatically on images 2400 without a fastmap. 2401 default: 0 2402 2403 CONFIG_MTD_UBI_FM_DEBUG 2404 Enable UBI fastmap debug 2405 default: 0 2406 2407- SPL framework 2408 CONFIG_SPL 2409 Enable building of SPL globally. 2410 2411 CONFIG_SPL_LDSCRIPT 2412 LDSCRIPT for linking the SPL binary. 2413 2414 CONFIG_SPL_MAX_FOOTPRINT 2415 Maximum size in memory allocated to the SPL, BSS included. 2416 When defined, the linker checks that the actual memory 2417 used by SPL from _start to __bss_end does not exceed it. 2418 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE 2419 must not be both defined at the same time. 2420 2421 CONFIG_SPL_MAX_SIZE 2422 Maximum size of the SPL image (text, data, rodata, and 2423 linker lists sections), BSS excluded. 2424 When defined, the linker checks that the actual size does 2425 not exceed it. 2426 2427 CONFIG_SPL_TEXT_BASE 2428 TEXT_BASE for linking the SPL binary. 2429 2430 CONFIG_SPL_RELOC_TEXT_BASE 2431 Address to relocate to. If unspecified, this is equal to 2432 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done). 2433 2434 CONFIG_SPL_BSS_START_ADDR 2435 Link address for the BSS within the SPL binary. 2436 2437 CONFIG_SPL_BSS_MAX_SIZE 2438 Maximum size in memory allocated to the SPL BSS. 2439 When defined, the linker checks that the actual memory used 2440 by SPL from __bss_start to __bss_end does not exceed it. 2441 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE 2442 must not be both defined at the same time. 2443 2444 CONFIG_SPL_STACK 2445 Adress of the start of the stack SPL will use 2446 2447 CONFIG_SPL_PANIC_ON_RAW_IMAGE 2448 When defined, SPL will panic() if the image it has 2449 loaded does not have a signature. 2450 Defining this is useful when code which loads images 2451 in SPL cannot guarantee that absolutely all read errors 2452 will be caught. 2453 An example is the LPC32XX MLC NAND driver, which will 2454 consider that a completely unreadable NAND block is bad, 2455 and thus should be skipped silently. 2456 2457 CONFIG_SPL_RELOC_STACK 2458 Adress of the start of the stack SPL will use after 2459 relocation. If unspecified, this is equal to 2460 CONFIG_SPL_STACK. 2461 2462 CONFIG_SYS_SPL_MALLOC_START 2463 Starting address of the malloc pool used in SPL. 2464 When this option is set the full malloc is used in SPL and 2465 it is set up by spl_init() and before that, the simple malloc() 2466 can be used if CONFIG_SYS_MALLOC_F is defined. 2467 2468 CONFIG_SYS_SPL_MALLOC_SIZE 2469 The size of the malloc pool used in SPL. 2470 2471 CONFIG_SPL_OS_BOOT 2472 Enable booting directly to an OS from SPL. 2473 See also: doc/README.falcon 2474 2475 CONFIG_SPL_DISPLAY_PRINT 2476 For ARM, enable an optional function to print more information 2477 about the running system. 2478 2479 CONFIG_SPL_INIT_MINIMAL 2480 Arch init code should be built for a very small image 2481 2482 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION 2483 Partition on the MMC to load U-Boot from when the MMC is being 2484 used in raw mode 2485 2486 CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR 2487 Sector to load kernel uImage from when MMC is being 2488 used in raw mode (for Falcon mode) 2489 2490 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR, 2491 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS 2492 Sector and number of sectors to load kernel argument 2493 parameters from when MMC is being used in raw mode 2494 (for falcon mode) 2495 2496 CONFIG_SYS_MMCSD_FS_BOOT_PARTITION 2497 Partition on the MMC to load U-Boot from when the MMC is being 2498 used in fs mode 2499 2500 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME 2501 Filename to read to load U-Boot when reading from filesystem 2502 2503 CONFIG_SPL_FS_LOAD_KERNEL_NAME 2504 Filename to read to load kernel uImage when reading 2505 from filesystem (for Falcon mode) 2506 2507 CONFIG_SPL_FS_LOAD_ARGS_NAME 2508 Filename to read to load kernel argument parameters 2509 when reading from filesystem (for Falcon mode) 2510 2511 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND 2512 Set this for NAND SPL on PPC mpc83xx targets, so that 2513 start.S waits for the rest of the SPL to load before 2514 continuing (the hardware starts execution after just 2515 loading the first page rather than the full 4K). 2516 2517 CONFIG_SPL_SKIP_RELOCATE 2518 Avoid SPL relocation 2519 2520 CONFIG_SPL_NAND_BASE 2521 Include nand_base.c in the SPL. Requires 2522 CONFIG_SPL_NAND_DRIVERS. 2523 2524 CONFIG_SPL_NAND_DRIVERS 2525 SPL uses normal NAND drivers, not minimal drivers. 2526 2527 CONFIG_SPL_NAND_IDENT 2528 SPL uses the chip ID list to identify the NAND flash. 2529 Requires CONFIG_SPL_NAND_BASE. 2530 2531 CONFIG_SPL_NAND_ECC 2532 Include standard software ECC in the SPL 2533 2534 CONFIG_SPL_NAND_SIMPLE 2535 Support for NAND boot using simple NAND drivers that 2536 expose the cmd_ctrl() interface. 2537 2538 CONFIG_SPL_UBI 2539 Support for a lightweight UBI (fastmap) scanner and 2540 loader 2541 2542 CONFIG_SPL_NAND_RAW_ONLY 2543 Support to boot only raw u-boot.bin images. Use this only 2544 if you need to save space. 2545 2546 CONFIG_SPL_COMMON_INIT_DDR 2547 Set for common ddr init with serial presence detect in 2548 SPL binary. 2549 2550 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT, 2551 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE, 2552 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS, 2553 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE, 2554 CONFIG_SYS_NAND_ECCBYTES 2555 Defines the size and behavior of the NAND that SPL uses 2556 to read U-Boot 2557 2558 CONFIG_SPL_NAND_BOOT 2559 Add support NAND boot 2560 2561 CONFIG_SYS_NAND_U_BOOT_OFFS 2562 Location in NAND to read U-Boot from 2563 2564 CONFIG_SYS_NAND_U_BOOT_DST 2565 Location in memory to load U-Boot to 2566 2567 CONFIG_SYS_NAND_U_BOOT_SIZE 2568 Size of image to load 2569 2570 CONFIG_SYS_NAND_U_BOOT_START 2571 Entry point in loaded image to jump to 2572 2573 CONFIG_SYS_NAND_HW_ECC_OOBFIRST 2574 Define this if you need to first read the OOB and then the 2575 data. This is used, for example, on davinci platforms. 2576 2577 CONFIG_SPL_RAM_DEVICE 2578 Support for running image already present in ram, in SPL binary 2579 2580 CONFIG_SPL_PAD_TO 2581 Image offset to which the SPL should be padded before appending 2582 the SPL payload. By default, this is defined as 2583 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined. 2584 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL 2585 payload without any padding, or >= CONFIG_SPL_MAX_SIZE. 2586 2587 CONFIG_SPL_TARGET 2588 Final target image containing SPL and payload. Some SPLs 2589 use an arch-specific makefile fragment instead, for 2590 example if more than one image needs to be produced. 2591 2592 CONFIG_SPL_FIT_PRINT 2593 Printing information about a FIT image adds quite a bit of 2594 code to SPL. So this is normally disabled in SPL. Use this 2595 option to re-enable it. This will affect the output of the 2596 bootm command when booting a FIT image. 2597 2598- TPL framework 2599 CONFIG_TPL 2600 Enable building of TPL globally. 2601 2602 CONFIG_TPL_PAD_TO 2603 Image offset to which the TPL should be padded before appending 2604 the TPL payload. By default, this is defined as 2605 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined. 2606 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL 2607 payload without any padding, or >= CONFIG_SPL_MAX_SIZE. 2608 2609- Interrupt support (PPC): 2610 2611 There are common interrupt_init() and timer_interrupt() 2612 for all PPC archs. interrupt_init() calls interrupt_init_cpu() 2613 for CPU specific initialization. interrupt_init_cpu() 2614 should set decrementer_count to appropriate value. If 2615 CPU resets decrementer automatically after interrupt 2616 (ppc4xx) it should set decrementer_count to zero. 2617 timer_interrupt() calls timer_interrupt_cpu() for CPU 2618 specific handling. If board has watchdog / status_led 2619 / other_activity_monitor it works automatically from 2620 general timer_interrupt(). 2621 2622 2623Board initialization settings: 2624------------------------------ 2625 2626During Initialization u-boot calls a number of board specific functions 2627to allow the preparation of board specific prerequisites, e.g. pin setup 2628before drivers are initialized. To enable these callbacks the 2629following configuration macros have to be defined. Currently this is 2630architecture specific, so please check arch/your_architecture/lib/board.c 2631typically in board_init_f() and board_init_r(). 2632 2633- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f() 2634- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r() 2635- CONFIG_BOARD_LATE_INIT: Call board_late_init() 2636- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init() 2637 2638Configuration Settings: 2639----------------------- 2640 2641- CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit. 2642 Optionally it can be defined to support 64-bit memory commands. 2643 2644- CONFIG_SYS_LONGHELP: Defined when you want long help messages included; 2645 undefine this when you're short of memory. 2646 2647- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default 2648 width of the commands listed in the 'help' command output. 2649 2650- CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to 2651 prompt for user input. 2652 2653- CONFIG_SYS_CBSIZE: Buffer size for input from the Console 2654 2655- CONFIG_SYS_PBSIZE: Buffer size for Console output 2656 2657- CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands 2658 2659- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to 2660 the application (usually a Linux kernel) when it is 2661 booted 2662 2663- CONFIG_SYS_BAUDRATE_TABLE: 2664 List of legal baudrate settings for this board. 2665 2666- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END: 2667 Begin and End addresses of the area used by the 2668 simple memory test. 2669 2670- CONFIG_SYS_MEMTEST_SCRATCH: 2671 Scratch address used by the alternate memory test 2672 You only need to set this if address zero isn't writeable 2673 2674- CONFIG_SYS_MEM_RESERVE_SECURE 2675 Only implemented for ARMv8 for now. 2676 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory 2677 is substracted from total RAM and won't be reported to OS. 2678 This memory can be used as secure memory. A variable 2679 gd->arch.secure_ram is used to track the location. In systems 2680 the RAM base is not zero, or RAM is divided into banks, 2681 this variable needs to be recalcuated to get the address. 2682 2683- CONFIG_SYS_MEM_TOP_HIDE: 2684 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header, 2685 this specified memory area will get subtracted from the top 2686 (end) of RAM and won't get "touched" at all by U-Boot. By 2687 fixing up gd->ram_size the Linux kernel should gets passed 2688 the now "corrected" memory size and won't touch it either. 2689 This should work for arch/ppc and arch/powerpc. Only Linux 2690 board ports in arch/powerpc with bootwrapper support that 2691 recalculate the memory size from the SDRAM controller setup 2692 will have to get fixed in Linux additionally. 2693 2694 This option can be used as a workaround for the 440EPx/GRx 2695 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't 2696 be touched. 2697 2698 WARNING: Please make sure that this value is a multiple of 2699 the Linux page size (normally 4k). If this is not the case, 2700 then the end address of the Linux memory will be located at a 2701 non page size aligned address and this could cause major 2702 problems. 2703 2704- CONFIG_SYS_LOADS_BAUD_CHANGE: 2705 Enable temporary baudrate change while serial download 2706 2707- CONFIG_SYS_SDRAM_BASE: 2708 Physical start address of SDRAM. _Must_ be 0 here. 2709 2710- CONFIG_SYS_FLASH_BASE: 2711 Physical start address of Flash memory. 2712 2713- CONFIG_SYS_MONITOR_BASE: 2714 Physical start address of boot monitor code (set by 2715 make config files to be same as the text base address 2716 (CONFIG_SYS_TEXT_BASE) used when linking) - same as 2717 CONFIG_SYS_FLASH_BASE when booting from flash. 2718 2719- CONFIG_SYS_MONITOR_LEN: 2720 Size of memory reserved for monitor code, used to 2721 determine _at_compile_time_ (!) if the environment is 2722 embedded within the U-Boot image, or in a separate 2723 flash sector. 2724 2725- CONFIG_SYS_MALLOC_LEN: 2726 Size of DRAM reserved for malloc() use. 2727 2728- CONFIG_SYS_MALLOC_F_LEN 2729 Size of the malloc() pool for use before relocation. If 2730 this is defined, then a very simple malloc() implementation 2731 will become available before relocation. The address is just 2732 below the global data, and the stack is moved down to make 2733 space. 2734 2735 This feature allocates regions with increasing addresses 2736 within the region. calloc() is supported, but realloc() 2737 is not available. free() is supported but does nothing. 2738 The memory will be freed (or in fact just forgotten) when 2739 U-Boot relocates itself. 2740 2741- CONFIG_SYS_MALLOC_SIMPLE 2742 Provides a simple and small malloc() and calloc() for those 2743 boards which do not use the full malloc in SPL (which is 2744 enabled with CONFIG_SYS_SPL_MALLOC_START). 2745 2746- CONFIG_SYS_NONCACHED_MEMORY: 2747 Size of non-cached memory area. This area of memory will be 2748 typically located right below the malloc() area and mapped 2749 uncached in the MMU. This is useful for drivers that would 2750 otherwise require a lot of explicit cache maintenance. For 2751 some drivers it's also impossible to properly maintain the 2752 cache. For example if the regions that need to be flushed 2753 are not a multiple of the cache-line size, *and* padding 2754 cannot be allocated between the regions to align them (i.e. 2755 if the HW requires a contiguous array of regions, and the 2756 size of each region is not cache-aligned), then a flush of 2757 one region may result in overwriting data that hardware has 2758 written to another region in the same cache-line. This can 2759 happen for example in network drivers where descriptors for 2760 buffers are typically smaller than the CPU cache-line (e.g. 2761 16 bytes vs. 32 or 64 bytes). 2762 2763 Non-cached memory is only supported on 32-bit ARM at present. 2764 2765- CONFIG_SYS_BOOTM_LEN: 2766 Normally compressed uImages are limited to an 2767 uncompressed size of 8 MBytes. If this is not enough, 2768 you can define CONFIG_SYS_BOOTM_LEN in your board config file 2769 to adjust this setting to your needs. 2770 2771- CONFIG_SYS_BOOTMAPSZ: 2772 Maximum size of memory mapped by the startup code of 2773 the Linux kernel; all data that must be processed by 2774 the Linux kernel (bd_info, boot arguments, FDT blob if 2775 used) must be put below this limit, unless "bootm_low" 2776 environment variable is defined and non-zero. In such case 2777 all data for the Linux kernel must be between "bootm_low" 2778 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment 2779 variable "bootm_mapsize" will override the value of 2780 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined, 2781 then the value in "bootm_size" will be used instead. 2782 2783- CONFIG_SYS_BOOT_RAMDISK_HIGH: 2784 Enable initrd_high functionality. If defined then the 2785 initrd_high feature is enabled and the bootm ramdisk subcommand 2786 is enabled. 2787 2788- CONFIG_SYS_BOOT_GET_CMDLINE: 2789 Enables allocating and saving kernel cmdline in space between 2790 "bootm_low" and "bootm_low" + BOOTMAPSZ. 2791 2792- CONFIG_SYS_BOOT_GET_KBD: 2793 Enables allocating and saving a kernel copy of the bd_info in 2794 space between "bootm_low" and "bootm_low" + BOOTMAPSZ. 2795 2796- CONFIG_SYS_MAX_FLASH_BANKS: 2797 Max number of Flash memory banks 2798 2799- CONFIG_SYS_MAX_FLASH_SECT: 2800 Max number of sectors on a Flash chip 2801 2802- CONFIG_SYS_FLASH_ERASE_TOUT: 2803 Timeout for Flash erase operations (in ms) 2804 2805- CONFIG_SYS_FLASH_WRITE_TOUT: 2806 Timeout for Flash write operations (in ms) 2807 2808- CONFIG_SYS_FLASH_LOCK_TOUT 2809 Timeout for Flash set sector lock bit operation (in ms) 2810 2811- CONFIG_SYS_FLASH_UNLOCK_TOUT 2812 Timeout for Flash clear lock bits operation (in ms) 2813 2814- CONFIG_SYS_FLASH_PROTECTION 2815 If defined, hardware flash sectors protection is used 2816 instead of U-Boot software protection. 2817 2818- CONFIG_SYS_DIRECT_FLASH_TFTP: 2819 2820 Enable TFTP transfers directly to flash memory; 2821 without this option such a download has to be 2822 performed in two steps: (1) download to RAM, and (2) 2823 copy from RAM to flash. 2824 2825 The two-step approach is usually more reliable, since 2826 you can check if the download worked before you erase 2827 the flash, but in some situations (when system RAM is 2828 too limited to allow for a temporary copy of the 2829 downloaded image) this option may be very useful. 2830 2831- CONFIG_SYS_FLASH_CFI: 2832 Define if the flash driver uses extra elements in the 2833 common flash structure for storing flash geometry. 2834 2835- CONFIG_FLASH_CFI_DRIVER 2836 This option also enables the building of the cfi_flash driver 2837 in the drivers directory 2838 2839- CONFIG_FLASH_CFI_MTD 2840 This option enables the building of the cfi_mtd driver 2841 in the drivers directory. The driver exports CFI flash 2842 to the MTD layer. 2843 2844- CONFIG_SYS_FLASH_USE_BUFFER_WRITE 2845 Use buffered writes to flash. 2846 2847- CONFIG_FLASH_SPANSION_S29WS_N 2848 s29ws-n MirrorBit flash has non-standard addresses for buffered 2849 write commands. 2850 2851- CONFIG_SYS_FLASH_QUIET_TEST 2852 If this option is defined, the common CFI flash doesn't 2853 print it's warning upon not recognized FLASH banks. This 2854 is useful, if some of the configured banks are only 2855 optionally available. 2856 2857- CONFIG_FLASH_SHOW_PROGRESS 2858 If defined (must be an integer), print out countdown 2859 digits and dots. Recommended value: 45 (9..1) for 80 2860 column displays, 15 (3..1) for 40 column displays. 2861 2862- CONFIG_FLASH_VERIFY 2863 If defined, the content of the flash (destination) is compared 2864 against the source after the write operation. An error message 2865 will be printed when the contents are not identical. 2866 Please note that this option is useless in nearly all cases, 2867 since such flash programming errors usually are detected earlier 2868 while unprotecting/erasing/programming. Please only enable 2869 this option if you really know what you are doing. 2870 2871- CONFIG_SYS_RX_ETH_BUFFER: 2872 Defines the number of Ethernet receive buffers. On some 2873 Ethernet controllers it is recommended to set this value 2874 to 8 or even higher (EEPRO100 or 405 EMAC), since all 2875 buffers can be full shortly after enabling the interface 2876 on high Ethernet traffic. 2877 Defaults to 4 if not defined. 2878 2879- CONFIG_ENV_MAX_ENTRIES 2880 2881 Maximum number of entries in the hash table that is used 2882 internally to store the environment settings. The default 2883 setting is supposed to be generous and should work in most 2884 cases. This setting can be used to tune behaviour; see 2885 lib/hashtable.c for details. 2886 2887- CONFIG_ENV_FLAGS_LIST_DEFAULT 2888- CONFIG_ENV_FLAGS_LIST_STATIC 2889 Enable validation of the values given to environment variables when 2890 calling env set. Variables can be restricted to only decimal, 2891 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined, 2892 the variables can also be restricted to IP address or MAC address. 2893 2894 The format of the list is: 2895 type_attribute = [s|d|x|b|i|m] 2896 access_attribute = [a|r|o|c] 2897 attributes = type_attribute[access_attribute] 2898 entry = variable_name[:attributes] 2899 list = entry[,list] 2900 2901 The type attributes are: 2902 s - String (default) 2903 d - Decimal 2904 x - Hexadecimal 2905 b - Boolean ([1yYtT|0nNfF]) 2906 i - IP address 2907 m - MAC address 2908 2909 The access attributes are: 2910 a - Any (default) 2911 r - Read-only 2912 o - Write-once 2913 c - Change-default 2914 2915 - CONFIG_ENV_FLAGS_LIST_DEFAULT 2916 Define this to a list (string) to define the ".flags" 2917 environment variable in the default or embedded environment. 2918 2919 - CONFIG_ENV_FLAGS_LIST_STATIC 2920 Define this to a list (string) to define validation that 2921 should be done if an entry is not found in the ".flags" 2922 environment variable. To override a setting in the static 2923 list, simply add an entry for the same variable name to the 2924 ".flags" variable. 2925 2926 If CONFIG_REGEX is defined, the variable_name above is evaluated as a 2927 regular expression. This allows multiple variables to define the same 2928 flags without explicitly listing them for each variable. 2929 2930- CONFIG_ENV_ACCESS_IGNORE_FORCE 2931 If defined, don't allow the -f switch to env set override variable 2932 access flags. 2933 2934The following definitions that deal with the placement and management 2935of environment data (variable area); in general, we support the 2936following configurations: 2937 2938- CONFIG_BUILD_ENVCRC: 2939 2940 Builds up envcrc with the target environment so that external utils 2941 may easily extract it and embed it in final U-Boot images. 2942 2943BE CAREFUL! The first access to the environment happens quite early 2944in U-Boot initialization (when we try to get the setting of for the 2945console baudrate). You *MUST* have mapped your NVRAM area then, or 2946U-Boot will hang. 2947 2948Please note that even with NVRAM we still use a copy of the 2949environment in RAM: we could work on NVRAM directly, but we want to 2950keep settings there always unmodified except somebody uses "saveenv" 2951to save the current settings. 2952 2953BE CAREFUL! For some special cases, the local device can not use 2954"saveenv" command. For example, the local device will get the 2955environment stored in a remote NOR flash by SRIO or PCIE link, 2956but it can not erase, write this NOR flash by SRIO or PCIE interface. 2957 2958- CONFIG_NAND_ENV_DST 2959 2960 Defines address in RAM to which the nand_spl code should copy the 2961 environment. If redundant environment is used, it will be copied to 2962 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE. 2963 2964Please note that the environment is read-only until the monitor 2965has been relocated to RAM and a RAM copy of the environment has been 2966created; also, when using EEPROM you will have to use env_get_f() 2967until then to read environment variables. 2968 2969The environment is protected by a CRC32 checksum. Before the monitor 2970is relocated into RAM, as a result of a bad CRC you will be working 2971with the compiled-in default environment - *silently*!!! [This is 2972necessary, because the first environment variable we need is the 2973"baudrate" setting for the console - if we have a bad CRC, we don't 2974have any device yet where we could complain.] 2975 2976Note: once the monitor has been relocated, then it will complain if 2977the default environment is used; a new CRC is computed as soon as you 2978use the "saveenv" command to store a valid environment. 2979 2980- CONFIG_SYS_FAULT_ECHO_LINK_DOWN: 2981 Echo the inverted Ethernet link state to the fault LED. 2982 2983 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR 2984 also needs to be defined. 2985 2986- CONFIG_SYS_FAULT_MII_ADDR: 2987 MII address of the PHY to check for the Ethernet link state. 2988 2989- CONFIG_NS16550_MIN_FUNCTIONS: 2990 Define this if you desire to only have use of the NS16550_init 2991 and NS16550_putc functions for the serial driver located at 2992 drivers/serial/ns16550.c. This option is useful for saving 2993 space for already greatly restricted images, including but not 2994 limited to NAND_SPL configurations. 2995 2996- CONFIG_DISPLAY_BOARDINFO 2997 Display information about the board that U-Boot is running on 2998 when U-Boot starts up. The board function checkboard() is called 2999 to do this. 3000 3001- CONFIG_DISPLAY_BOARDINFO_LATE 3002 Similar to the previous option, but display this information 3003 later, once stdio is running and output goes to the LCD, if 3004 present. 3005 3006- CONFIG_BOARD_SIZE_LIMIT: 3007 Maximum size of the U-Boot image. When defined, the 3008 build system checks that the actual size does not 3009 exceed it. 3010 3011Low Level (hardware related) configuration options: 3012--------------------------------------------------- 3013 3014- CONFIG_SYS_CACHELINE_SIZE: 3015 Cache Line Size of the CPU. 3016 3017- CONFIG_SYS_CCSRBAR_DEFAULT: 3018 Default (power-on reset) physical address of CCSR on Freescale 3019 PowerPC SOCs. 3020 3021- CONFIG_SYS_CCSRBAR: 3022 Virtual address of CCSR. On a 32-bit build, this is typically 3023 the same value as CONFIG_SYS_CCSRBAR_DEFAULT. 3024 3025- CONFIG_SYS_CCSRBAR_PHYS: 3026 Physical address of CCSR. CCSR can be relocated to a new 3027 physical address, if desired. In this case, this macro should 3028 be set to that address. Otherwise, it should be set to the 3029 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR 3030 is typically relocated on 36-bit builds. It is recommended 3031 that this macro be defined via the _HIGH and _LOW macros: 3032 3033 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH 3034 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW) 3035 3036- CONFIG_SYS_CCSRBAR_PHYS_HIGH: 3037 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically 3038 either 0 (32-bit build) or 0xF (36-bit build). This macro is 3039 used in assembly code, so it must not contain typecasts or 3040 integer size suffixes (e.g. "ULL"). 3041 3042- CONFIG_SYS_CCSRBAR_PHYS_LOW: 3043 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is 3044 used in assembly code, so it must not contain typecasts or 3045 integer size suffixes (e.g. "ULL"). 3046 3047- CONFIG_SYS_CCSR_DO_NOT_RELOCATE: 3048 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be 3049 forced to a value that ensures that CCSR is not relocated. 3050 3051- Floppy Disk Support: 3052 CONFIG_SYS_FDC_DRIVE_NUMBER 3053 3054 the default drive number (default value 0) 3055 3056 CONFIG_SYS_ISA_IO_STRIDE 3057 3058 defines the spacing between FDC chipset registers 3059 (default value 1) 3060 3061 CONFIG_SYS_ISA_IO_OFFSET 3062 3063 defines the offset of register from address. It 3064 depends on which part of the data bus is connected to 3065 the FDC chipset. (default value 0) 3066 3067 If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and 3068 CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their 3069 default value. 3070 3071 if CONFIG_SYS_FDC_HW_INIT is defined, then the function 3072 fdc_hw_init() is called at the beginning of the FDC 3073 setup. fdc_hw_init() must be provided by the board 3074 source code. It is used to make hardware-dependent 3075 initializations. 3076 3077- CONFIG_IDE_AHB: 3078 Most IDE controllers were designed to be connected with PCI 3079 interface. Only few of them were designed for AHB interface. 3080 When software is doing ATA command and data transfer to 3081 IDE devices through IDE-AHB controller, some additional 3082 registers accessing to these kind of IDE-AHB controller 3083 is required. 3084 3085- CONFIG_SYS_IMMR: Physical address of the Internal Memory. 3086 DO NOT CHANGE unless you know exactly what you're 3087 doing! (11-4) [MPC8xx systems only] 3088 3089- CONFIG_SYS_INIT_RAM_ADDR: 3090 3091 Start address of memory area that can be used for 3092 initial data and stack; please note that this must be 3093 writable memory that is working WITHOUT special 3094 initialization, i. e. you CANNOT use normal RAM which 3095 will become available only after programming the 3096 memory controller and running certain initialization 3097 sequences. 3098 3099 U-Boot uses the following memory types: 3100 - MPC8xx: IMMR (internal memory of the CPU) 3101 3102- CONFIG_SYS_GBL_DATA_OFFSET: 3103 3104 Offset of the initial data structure in the memory 3105 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually 3106 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial 3107 data is located at the end of the available space 3108 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE - 3109 GENERATED_GBL_DATA_SIZE), and the initial stack is just 3110 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR + 3111 CONFIG_SYS_GBL_DATA_OFFSET) downward. 3112 3113 Note: 3114 On the MPC824X (or other systems that use the data 3115 cache for initial memory) the address chosen for 3116 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must 3117 point to an otherwise UNUSED address space between 3118 the top of RAM and the start of the PCI space. 3119 3120- CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27) 3121 3122- CONFIG_SYS_OR_TIMING_SDRAM: 3123 SDRAM timing 3124 3125- CONFIG_SYS_MAMR_PTA: 3126 periodic timer for refresh 3127 3128- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM, 3129 CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP, 3130 CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM, 3131 CONFIG_SYS_BR1_PRELIM: 3132 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH) 3133 3134- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE, 3135 CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM, 3136 CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM: 3137 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM) 3138 3139- CONFIG_PCI_ENUM_ONLY 3140 Only scan through and get the devices on the buses. 3141 Don't do any setup work, presumably because someone or 3142 something has already done it, and we don't need to do it 3143 a second time. Useful for platforms that are pre-booted 3144 by coreboot or similar. 3145 3146- CONFIG_PCI_INDIRECT_BRIDGE: 3147 Enable support for indirect PCI bridges. 3148 3149- CONFIG_SYS_SRIO: 3150 Chip has SRIO or not 3151 3152- CONFIG_SRIO1: 3153 Board has SRIO 1 port available 3154 3155- CONFIG_SRIO2: 3156 Board has SRIO 2 port available 3157 3158- CONFIG_SRIO_PCIE_BOOT_MASTER 3159 Board can support master function for Boot from SRIO and PCIE 3160 3161- CONFIG_SYS_SRIOn_MEM_VIRT: 3162 Virtual Address of SRIO port 'n' memory region 3163 3164- CONFIG_SYS_SRIOn_MEM_PHYS: 3165 Physical Address of SRIO port 'n' memory region 3166 3167- CONFIG_SYS_SRIOn_MEM_SIZE: 3168 Size of SRIO port 'n' memory region 3169 3170- CONFIG_SYS_NAND_BUSWIDTH_16BIT 3171 Defined to tell the NAND controller that the NAND chip is using 3172 a 16 bit bus. 3173 Not all NAND drivers use this symbol. 3174 Example of drivers that use it: 3175 - drivers/mtd/nand/raw/ndfc.c 3176 - drivers/mtd/nand/raw/mxc_nand.c 3177 3178- CONFIG_SYS_NDFC_EBC0_CFG 3179 Sets the EBC0_CFG register for the NDFC. If not defined 3180 a default value will be used. 3181 3182- CONFIG_SPD_EEPROM 3183 Get DDR timing information from an I2C EEPROM. Common 3184 with pluggable memory modules such as SODIMMs 3185 3186 SPD_EEPROM_ADDRESS 3187 I2C address of the SPD EEPROM 3188 3189- CONFIG_SYS_SPD_BUS_NUM 3190 If SPD EEPROM is on an I2C bus other than the first 3191 one, specify here. Note that the value must resolve 3192 to something your driver can deal with. 3193 3194- CONFIG_SYS_DDR_RAW_TIMING 3195 Get DDR timing information from other than SPD. Common with 3196 soldered DDR chips onboard without SPD. DDR raw timing 3197 parameters are extracted from datasheet and hard-coded into 3198 header files or board specific files. 3199 3200- CONFIG_FSL_DDR_INTERACTIVE 3201 Enable interactive DDR debugging. See doc/README.fsl-ddr. 3202 3203- CONFIG_FSL_DDR_SYNC_REFRESH 3204 Enable sync of refresh for multiple controllers. 3205 3206- CONFIG_FSL_DDR_BIST 3207 Enable built-in memory test for Freescale DDR controllers. 3208 3209- CONFIG_SYS_83XX_DDR_USES_CS0 3210 Only for 83xx systems. If specified, then DDR should 3211 be configured using CS0 and CS1 instead of CS2 and CS3. 3212 3213- CONFIG_RMII 3214 Enable RMII mode for all FECs. 3215 Note that this is a global option, we can't 3216 have one FEC in standard MII mode and another in RMII mode. 3217 3218- CONFIG_CRC32_VERIFY 3219 Add a verify option to the crc32 command. 3220 The syntax is: 3221 3222 => crc32 -v <address> <count> <crc32> 3223 3224 Where address/count indicate a memory area 3225 and crc32 is the correct crc32 which the 3226 area should have. 3227 3228- CONFIG_LOOPW 3229 Add the "loopw" memory command. This only takes effect if 3230 the memory commands are activated globally (CONFIG_CMD_MEMORY). 3231 3232- CONFIG_MX_CYCLIC 3233 Add the "mdc" and "mwc" memory commands. These are cyclic 3234 "md/mw" commands. 3235 Examples: 3236 3237 => mdc.b 10 4 500 3238 This command will print 4 bytes (10,11,12,13) each 500 ms. 3239 3240 => mwc.l 100 12345678 10 3241 This command will write 12345678 to address 100 all 10 ms. 3242 3243 This only takes effect if the memory commands are activated 3244 globally (CONFIG_CMD_MEMORY). 3245 3246- CONFIG_SKIP_LOWLEVEL_INIT 3247 [ARM, NDS32, MIPS, RISC-V only] If this variable is defined, then certain 3248 low level initializations (like setting up the memory 3249 controller) are omitted and/or U-Boot does not 3250 relocate itself into RAM. 3251 3252 Normally this variable MUST NOT be defined. The only 3253 exception is when U-Boot is loaded (to RAM) by some 3254 other boot loader or by a debugger which performs 3255 these initializations itself. 3256 3257- CONFIG_SKIP_LOWLEVEL_INIT_ONLY 3258 [ARM926EJ-S only] This allows just the call to lowlevel_init() 3259 to be skipped. The normal CP15 init (such as enabling the 3260 instruction cache) is still performed. 3261 3262- CONFIG_SPL_BUILD 3263 Modifies the behaviour of start.S when compiling a loader 3264 that is executed before the actual U-Boot. E.g. when 3265 compiling a NAND SPL. 3266 3267- CONFIG_TPL_BUILD 3268 Modifies the behaviour of start.S when compiling a loader 3269 that is executed after the SPL and before the actual U-Boot. 3270 It is loaded by the SPL. 3271 3272- CONFIG_SYS_MPC85XX_NO_RESETVEC 3273 Only for 85xx systems. If this variable is specified, the section 3274 .resetvec is not kept and the section .bootpg is placed in the 3275 previous 4k of the .text section. 3276 3277- CONFIG_ARCH_MAP_SYSMEM 3278 Generally U-Boot (and in particular the md command) uses 3279 effective address. It is therefore not necessary to regard 3280 U-Boot address as virtual addresses that need to be translated 3281 to physical addresses. However, sandbox requires this, since 3282 it maintains its own little RAM buffer which contains all 3283 addressable memory. This option causes some memory accesses 3284 to be mapped through map_sysmem() / unmap_sysmem(). 3285 3286- CONFIG_X86_RESET_VECTOR 3287 If defined, the x86 reset vector code is included. This is not 3288 needed when U-Boot is running from Coreboot. 3289 3290- CONFIG_SYS_NAND_NO_SUBPAGE_WRITE 3291 Option to disable subpage write in NAND driver 3292 driver that uses this: 3293 drivers/mtd/nand/raw/davinci_nand.c 3294 3295Freescale QE/FMAN Firmware Support: 3296----------------------------------- 3297 3298The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the 3299loading of "firmware", which is encoded in the QE firmware binary format. 3300This firmware often needs to be loaded during U-Boot booting, so macros 3301are used to identify the storage device (NOR flash, SPI, etc) and the address 3302within that device. 3303 3304- CONFIG_SYS_FMAN_FW_ADDR 3305 The address in the storage device where the FMAN microcode is located. The 3306 meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro 3307 is also specified. 3308 3309- CONFIG_SYS_QE_FW_ADDR 3310 The address in the storage device where the QE microcode is located. The 3311 meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro 3312 is also specified. 3313 3314- CONFIG_SYS_QE_FMAN_FW_LENGTH 3315 The maximum possible size of the firmware. The firmware binary format 3316 has a field that specifies the actual size of the firmware, but it 3317 might not be possible to read any part of the firmware unless some 3318 local storage is allocated to hold the entire firmware first. 3319 3320- CONFIG_SYS_QE_FMAN_FW_IN_NOR 3321 Specifies that QE/FMAN firmware is located in NOR flash, mapped as 3322 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the 3323 virtual address in NOR flash. 3324 3325- CONFIG_SYS_QE_FMAN_FW_IN_NAND 3326 Specifies that QE/FMAN firmware is located in NAND flash. 3327 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash. 3328 3329- CONFIG_SYS_QE_FMAN_FW_IN_MMC 3330 Specifies that QE/FMAN firmware is located on the primary SD/MMC 3331 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device. 3332 3333- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE 3334 Specifies that QE/FMAN firmware is located in the remote (master) 3335 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which 3336 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound 3337 window->master inbound window->master LAW->the ucode address in 3338 master's memory space. 3339 3340Freescale Layerscape Management Complex Firmware Support: 3341--------------------------------------------------------- 3342The Freescale Layerscape Management Complex (MC) supports the loading of 3343"firmware". 3344This firmware often needs to be loaded during U-Boot booting, so macros 3345are used to identify the storage device (NOR flash, SPI, etc) and the address 3346within that device. 3347 3348- CONFIG_FSL_MC_ENET 3349 Enable the MC driver for Layerscape SoCs. 3350 3351Freescale Layerscape Debug Server Support: 3352------------------------------------------- 3353The Freescale Layerscape Debug Server Support supports the loading of 3354"Debug Server firmware" and triggering SP boot-rom. 3355This firmware often needs to be loaded during U-Boot booting. 3356 3357- CONFIG_SYS_MC_RSV_MEM_ALIGN 3358 Define alignment of reserved memory MC requires 3359 3360Reproducible builds 3361------------------- 3362 3363In order to achieve reproducible builds, timestamps used in the U-Boot build 3364process have to be set to a fixed value. 3365 3366This is done using the SOURCE_DATE_EPOCH environment variable. 3367SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration 3368option for U-Boot or an environment variable in U-Boot. 3369 3370SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC. 3371 3372Building the Software: 3373====================== 3374 3375Building U-Boot has been tested in several native build environments 3376and in many different cross environments. Of course we cannot support 3377all possibly existing versions of cross development tools in all 3378(potentially obsolete) versions. In case of tool chain problems we 3379recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK) 3380which is extensively used to build and test U-Boot. 3381 3382If you are not using a native environment, it is assumed that you 3383have GNU cross compiling tools available in your path. In this case, 3384you must set the environment variable CROSS_COMPILE in your shell. 3385Note that no changes to the Makefile or any other source files are 3386necessary. For example using the ELDK on a 4xx CPU, please enter: 3387 3388 $ CROSS_COMPILE=ppc_4xx- 3389 $ export CROSS_COMPILE 3390 3391Note: If you wish to generate Windows versions of the utilities in 3392 the tools directory you can use the MinGW toolchain 3393 (http://www.mingw.org). Set your HOST tools to the MinGW 3394 toolchain and execute 'make tools'. For example: 3395 3396 $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools 3397 3398 Binaries such as tools/mkimage.exe will be created which can 3399 be executed on computers running Windows. 3400 3401U-Boot is intended to be simple to build. After installing the 3402sources you must configure U-Boot for one specific board type. This 3403is done by typing: 3404 3405 make NAME_defconfig 3406 3407where "NAME_defconfig" is the name of one of the existing configu- 3408rations; see boards.cfg for supported names. 3409 3410Note: for some board special configuration names may exist; check if 3411 additional information is available from the board vendor; for 3412 instance, the TQM823L systems are available without (standard) 3413 or with LCD support. You can select such additional "features" 3414 when choosing the configuration, i. e. 3415 3416 make TQM823L_defconfig 3417 - will configure for a plain TQM823L, i. e. no LCD support 3418 3419 make TQM823L_LCD_defconfig 3420 - will configure for a TQM823L with U-Boot console on LCD 3421 3422 etc. 3423 3424 3425Finally, type "make all", and you should get some working U-Boot 3426images ready for download to / installation on your system: 3427 3428- "u-boot.bin" is a raw binary image 3429- "u-boot" is an image in ELF binary format 3430- "u-boot.srec" is in Motorola S-Record format 3431 3432By default the build is performed locally and the objects are saved 3433in the source directory. One of the two methods can be used to change 3434this behavior and build U-Boot to some external directory: 3435 34361. Add O= to the make command line invocations: 3437 3438 make O=/tmp/build distclean 3439 make O=/tmp/build NAME_defconfig 3440 make O=/tmp/build all 3441 34422. Set environment variable KBUILD_OUTPUT to point to the desired location: 3443 3444 export KBUILD_OUTPUT=/tmp/build 3445 make distclean 3446 make NAME_defconfig 3447 make all 3448 3449Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment 3450variable. 3451 3452User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by 3453setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS. 3454For example to treat all compiler warnings as errors: 3455 3456 make KCFLAGS=-Werror 3457 3458Please be aware that the Makefiles assume you are using GNU make, so 3459for instance on NetBSD you might need to use "gmake" instead of 3460native "make". 3461 3462 3463If the system board that you have is not listed, then you will need 3464to port U-Boot to your hardware platform. To do this, follow these 3465steps: 3466 34671. Create a new directory to hold your board specific code. Add any 3468 files you need. In your board directory, you will need at least 3469 the "Makefile" and a "<board>.c". 34702. Create a new configuration file "include/configs/<board>.h" for 3471 your board. 34723. If you're porting U-Boot to a new CPU, then also create a new 3473 directory to hold your CPU specific code. Add any files you need. 34744. Run "make <board>_defconfig" with your new name. 34755. Type "make", and you should get a working "u-boot.srec" file 3476 to be installed on your target system. 34776. Debug and solve any problems that might arise. 3478 [Of course, this last step is much harder than it sounds.] 3479 3480 3481Testing of U-Boot Modifications, Ports to New Hardware, etc.: 3482============================================================== 3483 3484If you have modified U-Boot sources (for instance added a new board 3485or support for new devices, a new CPU, etc.) you are expected to 3486provide feedback to the other developers. The feedback normally takes 3487the form of a "patch", i. e. a context diff against a certain (latest 3488official or latest in the git repository) version of U-Boot sources. 3489 3490But before you submit such a patch, please verify that your modifi- 3491cation did not break existing code. At least make sure that *ALL* of 3492the supported boards compile WITHOUT ANY compiler warnings. To do so, 3493just run the buildman script (tools/buildman/buildman), which will 3494configure and build U-Boot for ALL supported system. Be warned, this 3495will take a while. Please see the buildman README, or run 'buildman -H' 3496for documentation. 3497 3498 3499See also "U-Boot Porting Guide" below. 3500 3501 3502Monitor Commands - Overview: 3503============================ 3504 3505go - start application at address 'addr' 3506run - run commands in an environment variable 3507bootm - boot application image from memory 3508bootp - boot image via network using BootP/TFTP protocol 3509bootz - boot zImage from memory 3510tftpboot- boot image via network using TFTP protocol 3511 and env variables "ipaddr" and "serverip" 3512 (and eventually "gatewayip") 3513tftpput - upload a file via network using TFTP protocol 3514rarpboot- boot image via network using RARP/TFTP protocol 3515diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd' 3516loads - load S-Record file over serial line 3517loadb - load binary file over serial line (kermit mode) 3518md - memory display 3519mm - memory modify (auto-incrementing) 3520nm - memory modify (constant address) 3521mw - memory write (fill) 3522cp - memory copy 3523cmp - memory compare 3524crc32 - checksum calculation 3525i2c - I2C sub-system 3526sspi - SPI utility commands 3527base - print or set address offset 3528printenv- print environment variables 3529setenv - set environment variables 3530saveenv - save environment variables to persistent storage 3531protect - enable or disable FLASH write protection 3532erase - erase FLASH memory 3533flinfo - print FLASH memory information 3534nand - NAND memory operations (see doc/README.nand) 3535bdinfo - print Board Info structure 3536iminfo - print header information for application image 3537coninfo - print console devices and informations 3538ide - IDE sub-system 3539loop - infinite loop on address range 3540loopw - infinite write loop on address range 3541mtest - simple RAM test 3542icache - enable or disable instruction cache 3543dcache - enable or disable data cache 3544reset - Perform RESET of the CPU 3545echo - echo args to console 3546version - print monitor version 3547help - print online help 3548? - alias for 'help' 3549 3550 3551Monitor Commands - Detailed Description: 3552======================================== 3553 3554TODO. 3555 3556For now: just type "help <command>". 3557 3558 3559Environment Variables: 3560====================== 3561 3562U-Boot supports user configuration using Environment Variables which 3563can be made persistent by saving to Flash memory. 3564 3565Environment Variables are set using "setenv", printed using 3566"printenv", and saved to Flash using "saveenv". Using "setenv" 3567without a value can be used to delete a variable from the 3568environment. As long as you don't save the environment you are 3569working with an in-memory copy. In case the Flash area containing the 3570environment is erased by accident, a default environment is provided. 3571 3572Some configuration options can be set using Environment Variables. 3573 3574List of environment variables (most likely not complete): 3575 3576 baudrate - see CONFIG_BAUDRATE 3577 3578 bootdelay - see CONFIG_BOOTDELAY 3579 3580 bootcmd - see CONFIG_BOOTCOMMAND 3581 3582 bootargs - Boot arguments when booting an RTOS image 3583 3584 bootfile - Name of the image to load with TFTP 3585 3586 bootm_low - Memory range available for image processing in the bootm 3587 command can be restricted. This variable is given as 3588 a hexadecimal number and defines lowest address allowed 3589 for use by the bootm command. See also "bootm_size" 3590 environment variable. Address defined by "bootm_low" is 3591 also the base of the initial memory mapping for the Linux 3592 kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and 3593 bootm_mapsize. 3594 3595 bootm_mapsize - Size of the initial memory mapping for the Linux kernel. 3596 This variable is given as a hexadecimal number and it 3597 defines the size of the memory region starting at base 3598 address bootm_low that is accessible by the Linux kernel 3599 during early boot. If unset, CONFIG_SYS_BOOTMAPSZ is used 3600 as the default value if it is defined, and bootm_size is 3601 used otherwise. 3602 3603 bootm_size - Memory range available for image processing in the bootm 3604 command can be restricted. This variable is given as 3605 a hexadecimal number and defines the size of the region 3606 allowed for use by the bootm command. See also "bootm_low" 3607 environment variable. 3608 3609 updatefile - Location of the software update file on a TFTP server, used 3610 by the automatic software update feature. Please refer to 3611 documentation in doc/README.update for more details. 3612 3613 autoload - if set to "no" (any string beginning with 'n'), 3614 "bootp" will just load perform a lookup of the 3615 configuration from the BOOTP server, but not try to 3616 load any image using TFTP 3617 3618 autostart - if set to "yes", an image loaded using the "bootp", 3619 "rarpboot", "tftpboot" or "diskboot" commands will 3620 be automatically started (by internally calling 3621 "bootm") 3622 3623 If set to "no", a standalone image passed to the 3624 "bootm" command will be copied to the load address 3625 (and eventually uncompressed), but NOT be started. 3626 This can be used to load and uncompress arbitrary 3627 data. 3628 3629 fdt_high - if set this restricts the maximum address that the 3630 flattened device tree will be copied into upon boot. 3631 For example, if you have a system with 1 GB memory 3632 at physical address 0x10000000, while Linux kernel 3633 only recognizes the first 704 MB as low memory, you 3634 may need to set fdt_high as 0x3C000000 to have the 3635 device tree blob be copied to the maximum address 3636 of the 704 MB low memory, so that Linux kernel can 3637 access it during the boot procedure. 3638 3639 If this is set to the special value 0xFFFFFFFF then 3640 the fdt will not be copied at all on boot. For this 3641 to work it must reside in writable memory, have 3642 sufficient padding on the end of it for u-boot to 3643 add the information it needs into it, and the memory 3644 must be accessible by the kernel. 3645 3646 fdtcontroladdr- if set this is the address of the control flattened 3647 device tree used by U-Boot when CONFIG_OF_CONTROL is 3648 defined. 3649 3650 i2cfast - (PPC405GP|PPC405EP only) 3651 if set to 'y' configures Linux I2C driver for fast 3652 mode (400kHZ). This environment variable is used in 3653 initialization code. So, for changes to be effective 3654 it must be saved and board must be reset. 3655 3656 initrd_high - restrict positioning of initrd images: 3657 If this variable is not set, initrd images will be 3658 copied to the highest possible address in RAM; this 3659 is usually what you want since it allows for 3660 maximum initrd size. If for some reason you want to 3661 make sure that the initrd image is loaded below the 3662 CONFIG_SYS_BOOTMAPSZ limit, you can set this environment 3663 variable to a value of "no" or "off" or "0". 3664 Alternatively, you can set it to a maximum upper 3665 address to use (U-Boot will still check that it 3666 does not overwrite the U-Boot stack and data). 3667 3668 For instance, when you have a system with 16 MB 3669 RAM, and want to reserve 4 MB from use by Linux, 3670 you can do this by adding "mem=12M" to the value of 3671 the "bootargs" variable. However, now you must make 3672 sure that the initrd image is placed in the first 3673 12 MB as well - this can be done with 3674 3675 setenv initrd_high 00c00000 3676 3677 If you set initrd_high to 0xFFFFFFFF, this is an 3678 indication to U-Boot that all addresses are legal 3679 for the Linux kernel, including addresses in flash 3680 memory. In this case U-Boot will NOT COPY the 3681 ramdisk at all. This may be useful to reduce the 3682 boot time on your system, but requires that this 3683 feature is supported by your Linux kernel. 3684 3685 ipaddr - IP address; needed for tftpboot command 3686 3687 loadaddr - Default load address for commands like "bootp", 3688 "rarpboot", "tftpboot", "loadb" or "diskboot" 3689 3690 loads_echo - see CONFIG_LOADS_ECHO 3691 3692 serverip - TFTP server IP address; needed for tftpboot command 3693 3694 bootretry - see CONFIG_BOOT_RETRY_TIME 3695 3696 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR 3697 3698 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR 3699 3700 ethprime - controls which interface is used first. 3701 3702 ethact - controls which interface is currently active. 3703 For example you can do the following 3704 3705 => setenv ethact FEC 3706 => ping 192.168.0.1 # traffic sent on FEC 3707 => setenv ethact SCC 3708 => ping 10.0.0.1 # traffic sent on SCC 3709 3710 ethrotate - When set to "no" U-Boot does not go through all 3711 available network interfaces. 3712 It just stays at the currently selected interface. 3713 3714 netretry - When set to "no" each network operation will 3715 either succeed or fail without retrying. 3716 When set to "once" the network operation will 3717 fail when all the available network interfaces 3718 are tried once without success. 3719 Useful on scripts which control the retry operation 3720 themselves. 3721 3722 npe_ucode - set load address for the NPE microcode 3723 3724 silent_linux - If set then Linux will be told to boot silently, by 3725 changing the console to be empty. If "yes" it will be 3726 made silent. If "no" it will not be made silent. If 3727 unset, then it will be made silent if the U-Boot console 3728 is silent. 3729 3730 tftpsrcp - If this is set, the value is used for TFTP's 3731 UDP source port. 3732 3733 tftpdstp - If this is set, the value is used for TFTP's UDP 3734 destination port instead of the Well Know Port 69. 3735 3736 tftpblocksize - Block size to use for TFTP transfers; if not set, 3737 we use the TFTP server's default block size 3738 3739 tftptimeout - Retransmission timeout for TFTP packets (in milli- 3740 seconds, minimum value is 1000 = 1 second). Defines 3741 when a packet is considered to be lost so it has to 3742 be retransmitted. The default is 5000 = 5 seconds. 3743 Lowering this value may make downloads succeed 3744 faster in networks with high packet loss rates or 3745 with unreliable TFTP servers. 3746 3747 tftptimeoutcountmax - maximum count of TFTP timeouts (no 3748 unit, minimum value = 0). Defines how many timeouts 3749 can happen during a single file transfer before that 3750 transfer is aborted. The default is 10, and 0 means 3751 'no timeouts allowed'. Increasing this value may help 3752 downloads succeed with high packet loss rates, or with 3753 unreliable TFTP servers or client hardware. 3754 3755 vlan - When set to a value < 4095 the traffic over 3756 Ethernet is encapsulated/received over 802.1q 3757 VLAN tagged frames. 3758 3759 bootpretryperiod - Period during which BOOTP/DHCP sends retries. 3760 Unsigned value, in milliseconds. If not set, the period will 3761 be either the default (28000), or a value based on 3762 CONFIG_NET_RETRY_COUNT, if defined. This value has 3763 precedence over the valu based on CONFIG_NET_RETRY_COUNT. 3764 3765The following image location variables contain the location of images 3766used in booting. The "Image" column gives the role of the image and is 3767not an environment variable name. The other columns are environment 3768variable names. "File Name" gives the name of the file on a TFTP 3769server, "RAM Address" gives the location in RAM the image will be 3770loaded to, and "Flash Location" gives the image's address in NOR 3771flash or offset in NAND flash. 3772 3773*Note* - these variables don't have to be defined for all boards, some 3774boards currently use other variables for these purposes, and some 3775boards use these variables for other purposes. 3776 3777Image File Name RAM Address Flash Location 3778----- --------- ----------- -------------- 3779u-boot u-boot u-boot_addr_r u-boot_addr 3780Linux kernel bootfile kernel_addr_r kernel_addr 3781device tree blob fdtfile fdt_addr_r fdt_addr 3782ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr 3783 3784The following environment variables may be used and automatically 3785updated by the network boot commands ("bootp" and "rarpboot"), 3786depending the information provided by your boot server: 3787 3788 bootfile - see above 3789 dnsip - IP address of your Domain Name Server 3790 dnsip2 - IP address of your secondary Domain Name Server 3791 gatewayip - IP address of the Gateway (Router) to use 3792 hostname - Target hostname 3793 ipaddr - see above 3794 netmask - Subnet Mask 3795 rootpath - Pathname of the root filesystem on the NFS server 3796 serverip - see above 3797 3798 3799There are two special Environment Variables: 3800 3801 serial# - contains hardware identification information such 3802 as type string and/or serial number 3803 ethaddr - Ethernet address 3804 3805These variables can be set only once (usually during manufacturing of 3806the board). U-Boot refuses to delete or overwrite these variables 3807once they have been set once. 3808 3809 3810Further special Environment Variables: 3811 3812 ver - Contains the U-Boot version string as printed 3813 with the "version" command. This variable is 3814 readonly (see CONFIG_VERSION_VARIABLE). 3815 3816 3817Please note that changes to some configuration parameters may take 3818only effect after the next boot (yes, that's just like Windoze :-). 3819 3820 3821Callback functions for environment variables: 3822--------------------------------------------- 3823 3824For some environment variables, the behavior of u-boot needs to change 3825when their values are changed. This functionality allows functions to 3826be associated with arbitrary variables. On creation, overwrite, or 3827deletion, the callback will provide the opportunity for some side 3828effect to happen or for the change to be rejected. 3829 3830The callbacks are named and associated with a function using the 3831U_BOOT_ENV_CALLBACK macro in your board or driver code. 3832 3833These callbacks are associated with variables in one of two ways. The 3834static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC 3835in the board configuration to a string that defines a list of 3836associations. The list must be in the following format: 3837 3838 entry = variable_name[:callback_name] 3839 list = entry[,list] 3840 3841If the callback name is not specified, then the callback is deleted. 3842Spaces are also allowed anywhere in the list. 3843 3844Callbacks can also be associated by defining the ".callbacks" variable 3845with the same list format above. Any association in ".callbacks" will 3846override any association in the static list. You can define 3847CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the 3848".callbacks" environment variable in the default or embedded environment. 3849 3850If CONFIG_REGEX is defined, the variable_name above is evaluated as a 3851regular expression. This allows multiple variables to be connected to 3852the same callback without explicitly listing them all out. 3853 3854The signature of the callback functions is: 3855 3856 int callback(const char *name, const char *value, enum env_op op, int flags) 3857 3858* name - changed environment variable 3859* value - new value of the environment variable 3860* op - operation (create, overwrite, or delete) 3861* flags - attributes of the environment variable change, see flags H_* in 3862 include/search.h 3863 3864The return value is 0 if the variable change is accepted and 1 otherwise. 3865 3866Command Line Parsing: 3867===================== 3868 3869There are two different command line parsers available with U-Boot: 3870the old "simple" one, and the much more powerful "hush" shell: 3871 3872Old, simple command line parser: 3873-------------------------------- 3874 3875- supports environment variables (through setenv / saveenv commands) 3876- several commands on one line, separated by ';' 3877- variable substitution using "... ${name} ..." syntax 3878- special characters ('$', ';') can be escaped by prefixing with '\', 3879 for example: 3880 setenv bootcmd bootm \${address} 3881- You can also escape text by enclosing in single apostrophes, for example: 3882 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off' 3883 3884Hush shell: 3885----------- 3886 3887- similar to Bourne shell, with control structures like 3888 if...then...else...fi, for...do...done; while...do...done, 3889 until...do...done, ... 3890- supports environment ("global") variables (through setenv / saveenv 3891 commands) and local shell variables (through standard shell syntax 3892 "name=value"); only environment variables can be used with "run" 3893 command 3894 3895General rules: 3896-------------- 3897 3898(1) If a command line (or an environment variable executed by a "run" 3899 command) contains several commands separated by semicolon, and 3900 one of these commands fails, then the remaining commands will be 3901 executed anyway. 3902 3903(2) If you execute several variables with one call to run (i. e. 3904 calling run with a list of variables as arguments), any failing 3905 command will cause "run" to terminate, i. e. the remaining 3906 variables are not executed. 3907 3908Note for Redundant Ethernet Interfaces: 3909======================================= 3910 3911Some boards come with redundant Ethernet interfaces; U-Boot supports 3912such configurations and is capable of automatic selection of a 3913"working" interface when needed. MAC assignment works as follows: 3914 3915Network interfaces are numbered eth0, eth1, eth2, ... Corresponding 3916MAC addresses can be stored in the environment as "ethaddr" (=>eth0), 3917"eth1addr" (=>eth1), "eth2addr", ... 3918 3919If the network interface stores some valid MAC address (for instance 3920in SROM), this is used as default address if there is NO correspon- 3921ding setting in the environment; if the corresponding environment 3922variable is set, this overrides the settings in the card; that means: 3923 3924o If the SROM has a valid MAC address, and there is no address in the 3925 environment, the SROM's address is used. 3926 3927o If there is no valid address in the SROM, and a definition in the 3928 environment exists, then the value from the environment variable is 3929 used. 3930 3931o If both the SROM and the environment contain a MAC address, and 3932 both addresses are the same, this MAC address is used. 3933 3934o If both the SROM and the environment contain a MAC address, and the 3935 addresses differ, the value from the environment is used and a 3936 warning is printed. 3937 3938o If neither SROM nor the environment contain a MAC address, an error 3939 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case 3940 a random, locally-assigned MAC is used. 3941 3942If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses 3943will be programmed into hardware as part of the initialization process. This 3944may be skipped by setting the appropriate 'ethmacskip' environment variable. 3945The naming convention is as follows: 3946"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc. 3947 3948Image Formats: 3949============== 3950 3951U-Boot is capable of booting (and performing other auxiliary operations on) 3952images in two formats: 3953 3954New uImage format (FIT) 3955----------------------- 3956 3957Flexible and powerful format based on Flattened Image Tree -- FIT (similar 3958to Flattened Device Tree). It allows the use of images with multiple 3959components (several kernels, ramdisks, etc.), with contents protected by 3960SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory. 3961 3962 3963Old uImage format 3964----------------- 3965 3966Old image format is based on binary files which can be basically anything, 3967preceded by a special header; see the definitions in include/image.h for 3968details; basically, the header defines the following image properties: 3969 3970* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD, 3971 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks, 3972 LynxOS, pSOS, QNX, RTEMS, INTEGRITY; 3973 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS, 3974 INTEGRITY). 3975* Target CPU Architecture (Provisions for Alpha, ARM, Intel x86, 3976 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit; 3977 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC). 3978* Compression Type (uncompressed, gzip, bzip2) 3979* Load Address 3980* Entry Point 3981* Image Name 3982* Image Timestamp 3983 3984The header is marked by a special Magic Number, and both the header 3985and the data portions of the image are secured against corruption by 3986CRC32 checksums. 3987 3988 3989Linux Support: 3990============== 3991 3992Although U-Boot should support any OS or standalone application 3993easily, the main focus has always been on Linux during the design of 3994U-Boot. 3995 3996U-Boot includes many features that so far have been part of some 3997special "boot loader" code within the Linux kernel. Also, any 3998"initrd" images to be used are no longer part of one big Linux image; 3999instead, kernel and "initrd" are separate images. This implementation 4000serves several purposes: 4001 4002- the same features can be used for other OS or standalone 4003 applications (for instance: using compressed images to reduce the 4004 Flash memory footprint) 4005 4006- it becomes much easier to port new Linux kernel versions because 4007 lots of low-level, hardware dependent stuff are done by U-Boot 4008 4009- the same Linux kernel image can now be used with different "initrd" 4010 images; of course this also means that different kernel images can 4011 be run with the same "initrd". This makes testing easier (you don't 4012 have to build a new "zImage.initrd" Linux image when you just 4013 change a file in your "initrd"). Also, a field-upgrade of the 4014 software is easier now. 4015 4016 4017Linux HOWTO: 4018============ 4019 4020Porting Linux to U-Boot based systems: 4021--------------------------------------- 4022 4023U-Boot cannot save you from doing all the necessary modifications to 4024configure the Linux device drivers for use with your target hardware 4025(no, we don't intend to provide a full virtual machine interface to 4026Linux :-). 4027 4028But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot). 4029 4030Just make sure your machine specific header file (for instance 4031include/asm-ppc/tqm8xx.h) includes the same definition of the Board 4032Information structure as we define in include/asm-<arch>/u-boot.h, 4033and make sure that your definition of IMAP_ADDR uses the same value 4034as your U-Boot configuration in CONFIG_SYS_IMMR. 4035 4036Note that U-Boot now has a driver model, a unified model for drivers. 4037If you are adding a new driver, plumb it into driver model. If there 4038is no uclass available, you are encouraged to create one. See 4039doc/driver-model. 4040 4041 4042Configuring the Linux kernel: 4043----------------------------- 4044 4045No specific requirements for U-Boot. Make sure you have some root 4046device (initial ramdisk, NFS) for your target system. 4047 4048 4049Building a Linux Image: 4050----------------------- 4051 4052With U-Boot, "normal" build targets like "zImage" or "bzImage" are 4053not used. If you use recent kernel source, a new build target 4054"uImage" will exist which automatically builds an image usable by 4055U-Boot. Most older kernels also have support for a "pImage" target, 4056which was introduced for our predecessor project PPCBoot and uses a 4057100% compatible format. 4058 4059Example: 4060 4061 make TQM850L_defconfig 4062 make oldconfig 4063 make dep 4064 make uImage 4065 4066The "uImage" build target uses a special tool (in 'tools/mkimage') to 4067encapsulate a compressed Linux kernel image with header information, 4068CRC32 checksum etc. for use with U-Boot. This is what we are doing: 4069 4070* build a standard "vmlinux" kernel image (in ELF binary format): 4071 4072* convert the kernel into a raw binary image: 4073 4074 ${CROSS_COMPILE}-objcopy -O binary \ 4075 -R .note -R .comment \ 4076 -S vmlinux linux.bin 4077 4078* compress the binary image: 4079 4080 gzip -9 linux.bin 4081 4082* package compressed binary image for U-Boot: 4083 4084 mkimage -A ppc -O linux -T kernel -C gzip \ 4085 -a 0 -e 0 -n "Linux Kernel Image" \ 4086 -d linux.bin.gz uImage 4087 4088 4089The "mkimage" tool can also be used to create ramdisk images for use 4090with U-Boot, either separated from the Linux kernel image, or 4091combined into one file. "mkimage" encapsulates the images with a 64 4092byte header containing information about target architecture, 4093operating system, image type, compression method, entry points, time 4094stamp, CRC32 checksums, etc. 4095 4096"mkimage" can be called in two ways: to verify existing images and 4097print the header information, or to build new images. 4098 4099In the first form (with "-l" option) mkimage lists the information 4100contained in the header of an existing U-Boot image; this includes 4101checksum verification: 4102 4103 tools/mkimage -l image 4104 -l ==> list image header information 4105 4106The second form (with "-d" option) is used to build a U-Boot image 4107from a "data file" which is used as image payload: 4108 4109 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \ 4110 -n name -d data_file image 4111 -A ==> set architecture to 'arch' 4112 -O ==> set operating system to 'os' 4113 -T ==> set image type to 'type' 4114 -C ==> set compression type 'comp' 4115 -a ==> set load address to 'addr' (hex) 4116 -e ==> set entry point to 'ep' (hex) 4117 -n ==> set image name to 'name' 4118 -d ==> use image data from 'datafile' 4119 4120Right now, all Linux kernels for PowerPC systems use the same load 4121address (0x00000000), but the entry point address depends on the 4122kernel version: 4123 4124- 2.2.x kernels have the entry point at 0x0000000C, 4125- 2.3.x and later kernels have the entry point at 0x00000000. 4126 4127So a typical call to build a U-Boot image would read: 4128 4129 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \ 4130 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \ 4131 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \ 4132 > examples/uImage.TQM850L 4133 Image Name: 2.4.4 kernel for TQM850L 4134 Created: Wed Jul 19 02:34:59 2000 4135 Image Type: PowerPC Linux Kernel Image (gzip compressed) 4136 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB 4137 Load Address: 0x00000000 4138 Entry Point: 0x00000000 4139 4140To verify the contents of the image (or check for corruption): 4141 4142 -> tools/mkimage -l examples/uImage.TQM850L 4143 Image Name: 2.4.4 kernel for TQM850L 4144 Created: Wed Jul 19 02:34:59 2000 4145 Image Type: PowerPC Linux Kernel Image (gzip compressed) 4146 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB 4147 Load Address: 0x00000000 4148 Entry Point: 0x00000000 4149 4150NOTE: for embedded systems where boot time is critical you can trade 4151speed for memory and install an UNCOMPRESSED image instead: this 4152needs more space in Flash, but boots much faster since it does not 4153need to be uncompressed: 4154 4155 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz 4156 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \ 4157 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \ 4158 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \ 4159 > examples/uImage.TQM850L-uncompressed 4160 Image Name: 2.4.4 kernel for TQM850L 4161 Created: Wed Jul 19 02:34:59 2000 4162 Image Type: PowerPC Linux Kernel Image (uncompressed) 4163 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB 4164 Load Address: 0x00000000 4165 Entry Point: 0x00000000 4166 4167 4168Similar you can build U-Boot images from a 'ramdisk.image.gz' file 4169when your kernel is intended to use an initial ramdisk: 4170 4171 -> tools/mkimage -n 'Simple Ramdisk Image' \ 4172 > -A ppc -O linux -T ramdisk -C gzip \ 4173 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd 4174 Image Name: Simple Ramdisk Image 4175 Created: Wed Jan 12 14:01:50 2000 4176 Image Type: PowerPC Linux RAMDisk Image (gzip compressed) 4177 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB 4178 Load Address: 0x00000000 4179 Entry Point: 0x00000000 4180 4181The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i" 4182option performs the converse operation of the mkimage's second form (the "-d" 4183option). Given an image built by mkimage, the dumpimage extracts a "data file" 4184from the image: 4185 4186 tools/dumpimage -i image -T type -p position data_file 4187 -i ==> extract from the 'image' a specific 'data_file' 4188 -T ==> set image type to 'type' 4189 -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image' 4190 4191 4192Installing a Linux Image: 4193------------------------- 4194 4195To downloading a U-Boot image over the serial (console) interface, 4196you must convert the image to S-Record format: 4197 4198 objcopy -I binary -O srec examples/image examples/image.srec 4199 4200The 'objcopy' does not understand the information in the U-Boot 4201image header, so the resulting S-Record file will be relative to 4202address 0x00000000. To load it to a given address, you need to 4203specify the target address as 'offset' parameter with the 'loads' 4204command. 4205 4206Example: install the image to address 0x40100000 (which on the 4207TQM8xxL is in the first Flash bank): 4208 4209 => erase 40100000 401FFFFF 4210 4211 .......... done 4212 Erased 8 sectors 4213 4214 => loads 40100000 4215 ## Ready for S-Record download ... 4216 ~>examples/image.srec 4217 1 2 3 4 5 6 7 8 9 10 11 12 13 ... 4218 ... 4219 15989 15990 15991 15992 4220 [file transfer complete] 4221 [connected] 4222 ## Start Addr = 0x00000000 4223 4224 4225You can check the success of the download using the 'iminfo' command; 4226this includes a checksum verification so you can be sure no data 4227corruption happened: 4228 4229 => imi 40100000 4230 4231 ## Checking Image at 40100000 ... 4232 Image Name: 2.2.13 for initrd on TQM850L 4233 Image Type: PowerPC Linux Kernel Image (gzip compressed) 4234 Data Size: 335725 Bytes = 327 kB = 0 MB 4235 Load Address: 00000000 4236 Entry Point: 0000000c 4237 Verifying Checksum ... OK 4238 4239 4240Boot Linux: 4241----------- 4242 4243The "bootm" command is used to boot an application that is stored in 4244memory (RAM or Flash). In case of a Linux kernel image, the contents 4245of the "bootargs" environment variable is passed to the kernel as 4246parameters. You can check and modify this variable using the 4247"printenv" and "setenv" commands: 4248 4249 4250 => printenv bootargs 4251 bootargs=root=/dev/ram 4252 4253 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2 4254 4255 => printenv bootargs 4256 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2 4257 4258 => bootm 40020000 4259 ## Booting Linux kernel at 40020000 ... 4260 Image Name: 2.2.13 for NFS on TQM850L 4261 Image Type: PowerPC Linux Kernel Image (gzip compressed) 4262 Data Size: 381681 Bytes = 372 kB = 0 MB 4263 Load Address: 00000000 4264 Entry Point: 0000000c 4265 Verifying Checksum ... OK 4266 Uncompressing Kernel Image ... OK 4267 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 4268 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2 4269 time_init: decrementer frequency = 187500000/60 4270 Calibrating delay loop... 49.77 BogoMIPS 4271 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000] 4272 ... 4273 4274If you want to boot a Linux kernel with initial RAM disk, you pass 4275the memory addresses of both the kernel and the initrd image (PPBCOOT 4276format!) to the "bootm" command: 4277 4278 => imi 40100000 40200000 4279 4280 ## Checking Image at 40100000 ... 4281 Image Name: 2.2.13 for initrd on TQM850L 4282 Image Type: PowerPC Linux Kernel Image (gzip compressed) 4283 Data Size: 335725 Bytes = 327 kB = 0 MB 4284 Load Address: 00000000 4285 Entry Point: 0000000c 4286 Verifying Checksum ... OK 4287 4288 ## Checking Image at 40200000 ... 4289 Image Name: Simple Ramdisk Image 4290 Image Type: PowerPC Linux RAMDisk Image (gzip compressed) 4291 Data Size: 566530 Bytes = 553 kB = 0 MB 4292 Load Address: 00000000 4293 Entry Point: 00000000 4294 Verifying Checksum ... OK 4295 4296 => bootm 40100000 40200000 4297 ## Booting Linux kernel at 40100000 ... 4298 Image Name: 2.2.13 for initrd on TQM850L 4299 Image Type: PowerPC Linux Kernel Image (gzip compressed) 4300 Data Size: 335725 Bytes = 327 kB = 0 MB 4301 Load Address: 00000000 4302 Entry Point: 0000000c 4303 Verifying Checksum ... OK 4304 Uncompressing Kernel Image ... OK 4305 ## Loading RAMDisk Image at 40200000 ... 4306 Image Name: Simple Ramdisk Image 4307 Image Type: PowerPC Linux RAMDisk Image (gzip compressed) 4308 Data Size: 566530 Bytes = 553 kB = 0 MB 4309 Load Address: 00000000 4310 Entry Point: 00000000 4311 Verifying Checksum ... OK 4312 Loading Ramdisk ... OK 4313 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 4314 Boot arguments: root=/dev/ram 4315 time_init: decrementer frequency = 187500000/60 4316 Calibrating delay loop... 49.77 BogoMIPS 4317 ... 4318 RAMDISK: Compressed image found at block 0 4319 VFS: Mounted root (ext2 filesystem). 4320 4321 bash# 4322 4323Boot Linux and pass a flat device tree: 4324----------- 4325 4326First, U-Boot must be compiled with the appropriate defines. See the section 4327titled "Linux Kernel Interface" above for a more in depth explanation. The 4328following is an example of how to start a kernel and pass an updated 4329flat device tree: 4330 4331=> print oftaddr 4332oftaddr=0x300000 4333=> print oft 4334oft=oftrees/mpc8540ads.dtb 4335=> tftp $oftaddr $oft 4336Speed: 1000, full duplex 4337Using TSEC0 device 4338TFTP from server 192.168.1.1; our IP address is 192.168.1.101 4339Filename 'oftrees/mpc8540ads.dtb'. 4340Load address: 0x300000 4341Loading: # 4342done 4343Bytes transferred = 4106 (100a hex) 4344=> tftp $loadaddr $bootfile 4345Speed: 1000, full duplex 4346Using TSEC0 device 4347TFTP from server 192.168.1.1; our IP address is 192.168.1.2 4348Filename 'uImage'. 4349Load address: 0x200000 4350Loading:############ 4351done 4352Bytes transferred = 1029407 (fb51f hex) 4353=> print loadaddr 4354loadaddr=200000 4355=> print oftaddr 4356oftaddr=0x300000 4357=> bootm $loadaddr - $oftaddr 4358## Booting image at 00200000 ... 4359 Image Name: Linux-2.6.17-dirty 4360 Image Type: PowerPC Linux Kernel Image (gzip compressed) 4361 Data Size: 1029343 Bytes = 1005.2 kB 4362 Load Address: 00000000 4363 Entry Point: 00000000 4364 Verifying Checksum ... OK 4365 Uncompressing Kernel Image ... OK 4366Booting using flat device tree at 0x300000 4367Using MPC85xx ADS machine description 4368Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb 4369[snip] 4370 4371 4372More About U-Boot Image Types: 4373------------------------------ 4374 4375U-Boot supports the following image types: 4376 4377 "Standalone Programs" are directly runnable in the environment 4378 provided by U-Boot; it is expected that (if they behave 4379 well) you can continue to work in U-Boot after return from 4380 the Standalone Program. 4381 "OS Kernel Images" are usually images of some Embedded OS which 4382 will take over control completely. Usually these programs 4383 will install their own set of exception handlers, device 4384 drivers, set up the MMU, etc. - this means, that you cannot 4385 expect to re-enter U-Boot except by resetting the CPU. 4386 "RAMDisk Images" are more or less just data blocks, and their 4387 parameters (address, size) are passed to an OS kernel that is 4388 being started. 4389 "Multi-File Images" contain several images, typically an OS 4390 (Linux) kernel image and one or more data images like 4391 RAMDisks. This construct is useful for instance when you want 4392 to boot over the network using BOOTP etc., where the boot 4393 server provides just a single image file, but you want to get 4394 for instance an OS kernel and a RAMDisk image. 4395 4396 "Multi-File Images" start with a list of image sizes, each 4397 image size (in bytes) specified by an "uint32_t" in network 4398 byte order. This list is terminated by an "(uint32_t)0". 4399 Immediately after the terminating 0 follow the images, one by 4400 one, all aligned on "uint32_t" boundaries (size rounded up to 4401 a multiple of 4 bytes). 4402 4403 "Firmware Images" are binary images containing firmware (like 4404 U-Boot or FPGA images) which usually will be programmed to 4405 flash memory. 4406 4407 "Script files" are command sequences that will be executed by 4408 U-Boot's command interpreter; this feature is especially 4409 useful when you configure U-Boot to use a real shell (hush) 4410 as command interpreter. 4411 4412Booting the Linux zImage: 4413------------------------- 4414 4415On some platforms, it's possible to boot Linux zImage. This is done 4416using the "bootz" command. The syntax of "bootz" command is the same 4417as the syntax of "bootm" command. 4418 4419Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply 4420kernel with raw initrd images. The syntax is slightly different, the 4421address of the initrd must be augmented by it's size, in the following 4422format: "<initrd addres>:<initrd size>". 4423 4424 4425Standalone HOWTO: 4426================= 4427 4428One of the features of U-Boot is that you can dynamically load and 4429run "standalone" applications, which can use some resources of 4430U-Boot like console I/O functions or interrupt services. 4431 4432Two simple examples are included with the sources: 4433 4434"Hello World" Demo: 4435------------------- 4436 4437'examples/hello_world.c' contains a small "Hello World" Demo 4438application; it is automatically compiled when you build U-Boot. 4439It's configured to run at address 0x00040004, so you can play with it 4440like that: 4441 4442 => loads 4443 ## Ready for S-Record download ... 4444 ~>examples/hello_world.srec 4445 1 2 3 4 5 6 7 8 9 10 11 ... 4446 [file transfer complete] 4447 [connected] 4448 ## Start Addr = 0x00040004 4449 4450 => go 40004 Hello World! This is a test. 4451 ## Starting application at 0x00040004 ... 4452 Hello World 4453 argc = 7 4454 argv[0] = "40004" 4455 argv[1] = "Hello" 4456 argv[2] = "World!" 4457 argv[3] = "This" 4458 argv[4] = "is" 4459 argv[5] = "a" 4460 argv[6] = "test." 4461 argv[7] = "<NULL>" 4462 Hit any key to exit ... 4463 4464 ## Application terminated, rc = 0x0 4465 4466Another example, which demonstrates how to register a CPM interrupt 4467handler with the U-Boot code, can be found in 'examples/timer.c'. 4468Here, a CPM timer is set up to generate an interrupt every second. 4469The interrupt service routine is trivial, just printing a '.' 4470character, but this is just a demo program. The application can be 4471controlled by the following keys: 4472 4473 ? - print current values og the CPM Timer registers 4474 b - enable interrupts and start timer 4475 e - stop timer and disable interrupts 4476 q - quit application 4477 4478 => loads 4479 ## Ready for S-Record download ... 4480 ~>examples/timer.srec 4481 1 2 3 4 5 6 7 8 9 10 11 ... 4482 [file transfer complete] 4483 [connected] 4484 ## Start Addr = 0x00040004 4485 4486 => go 40004 4487 ## Starting application at 0x00040004 ... 4488 TIMERS=0xfff00980 4489 Using timer 1 4490 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0 4491 4492Hit 'b': 4493 [q, b, e, ?] Set interval 1000000 us 4494 Enabling timer 4495Hit '?': 4496 [q, b, e, ?] ........ 4497 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0 4498Hit '?': 4499 [q, b, e, ?] . 4500 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0 4501Hit '?': 4502 [q, b, e, ?] . 4503 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0 4504Hit '?': 4505 [q, b, e, ?] . 4506 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0 4507Hit 'e': 4508 [q, b, e, ?] ...Stopping timer 4509Hit 'q': 4510 [q, b, e, ?] ## Application terminated, rc = 0x0 4511 4512 4513Minicom warning: 4514================ 4515 4516Over time, many people have reported problems when trying to use the 4517"minicom" terminal emulation program for serial download. I (wd) 4518consider minicom to be broken, and recommend not to use it. Under 4519Unix, I recommend to use C-Kermit for general purpose use (and 4520especially for kermit binary protocol download ("loadb" command), and 4521use "cu" for S-Record download ("loads" command). See 4522http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3. 4523for help with kermit. 4524 4525 4526Nevertheless, if you absolutely want to use it try adding this 4527configuration to your "File transfer protocols" section: 4528 4529 Name Program Name U/D FullScr IO-Red. Multi 4530 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N 4531 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N 4532 4533 4534NetBSD Notes: 4535============= 4536 4537Starting at version 0.9.2, U-Boot supports NetBSD both as host 4538(build U-Boot) and target system (boots NetBSD/mpc8xx). 4539 4540Building requires a cross environment; it is known to work on 4541NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also 4542need gmake since the Makefiles are not compatible with BSD make). 4543Note that the cross-powerpc package does not install include files; 4544attempting to build U-Boot will fail because <machine/ansi.h> is 4545missing. This file has to be installed and patched manually: 4546 4547 # cd /usr/pkg/cross/powerpc-netbsd/include 4548 # mkdir powerpc 4549 # ln -s powerpc machine 4550 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h 4551 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST 4552 4553Native builds *don't* work due to incompatibilities between native 4554and U-Boot include files. 4555 4556Booting assumes that (the first part of) the image booted is a 4557stage-2 loader which in turn loads and then invokes the kernel 4558proper. Loader sources will eventually appear in the NetBSD source 4559tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the 4560meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz 4561 4562 4563Implementation Internals: 4564========================= 4565 4566The following is not intended to be a complete description of every 4567implementation detail. However, it should help to understand the 4568inner workings of U-Boot and make it easier to port it to custom 4569hardware. 4570 4571 4572Initial Stack, Global Data: 4573--------------------------- 4574 4575The implementation of U-Boot is complicated by the fact that U-Boot 4576starts running out of ROM (flash memory), usually without access to 4577system RAM (because the memory controller is not initialized yet). 4578This means that we don't have writable Data or BSS segments, and BSS 4579is not initialized as zero. To be able to get a C environment working 4580at all, we have to allocate at least a minimal stack. Implementation 4581options for this are defined and restricted by the CPU used: Some CPU 4582models provide on-chip memory (like the IMMR area on MPC8xx and 4583MPC826x processors), on others (parts of) the data cache can be 4584locked as (mis-) used as memory, etc. 4585 4586 Chris Hallinan posted a good summary of these issues to the 4587 U-Boot mailing list: 4588 4589 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)? 4590 From: "Chris Hallinan" <clh@net1plus.com> 4591 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET) 4592 ... 4593 4594 Correct me if I'm wrong, folks, but the way I understand it 4595 is this: Using DCACHE as initial RAM for Stack, etc, does not 4596 require any physical RAM backing up the cache. The cleverness 4597 is that the cache is being used as a temporary supply of 4598 necessary storage before the SDRAM controller is setup. It's 4599 beyond the scope of this list to explain the details, but you 4600 can see how this works by studying the cache architecture and 4601 operation in the architecture and processor-specific manuals. 4602 4603 OCM is On Chip Memory, which I believe the 405GP has 4K. It 4604 is another option for the system designer to use as an 4605 initial stack/RAM area prior to SDRAM being available. Either 4606 option should work for you. Using CS 4 should be fine if your 4607 board designers haven't used it for something that would 4608 cause you grief during the initial boot! It is frequently not 4609 used. 4610 4611 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere 4612 with your processor/board/system design. The default value 4613 you will find in any recent u-boot distribution in 4614 walnut.h should work for you. I'd set it to a value larger 4615 than your SDRAM module. If you have a 64MB SDRAM module, set 4616 it above 400_0000. Just make sure your board has no resources 4617 that are supposed to respond to that address! That code in 4618 start.S has been around a while and should work as is when 4619 you get the config right. 4620 4621 -Chris Hallinan 4622 DS4.COM, Inc. 4623 4624It is essential to remember this, since it has some impact on the C 4625code for the initialization procedures: 4626 4627* Initialized global data (data segment) is read-only. Do not attempt 4628 to write it. 4629 4630* Do not use any uninitialized global data (or implicitly initialized 4631 as zero data - BSS segment) at all - this is undefined, initiali- 4632 zation is performed later (when relocating to RAM). 4633 4634* Stack space is very limited. Avoid big data buffers or things like 4635 that. 4636 4637Having only the stack as writable memory limits means we cannot use 4638normal global data to share information between the code. But it 4639turned out that the implementation of U-Boot can be greatly 4640simplified by making a global data structure (gd_t) available to all 4641functions. We could pass a pointer to this data as argument to _all_ 4642functions, but this would bloat the code. Instead we use a feature of 4643the GCC compiler (Global Register Variables) to share the data: we 4644place a pointer (gd) to the global data into a register which we 4645reserve for this purpose. 4646 4647When choosing a register for such a purpose we are restricted by the 4648relevant (E)ABI specifications for the current architecture, and by 4649GCC's implementation. 4650 4651For PowerPC, the following registers have specific use: 4652 R1: stack pointer 4653 R2: reserved for system use 4654 R3-R4: parameter passing and return values 4655 R5-R10: parameter passing 4656 R13: small data area pointer 4657 R30: GOT pointer 4658 R31: frame pointer 4659 4660 (U-Boot also uses R12 as internal GOT pointer. r12 4661 is a volatile register so r12 needs to be reset when 4662 going back and forth between asm and C) 4663 4664 ==> U-Boot will use R2 to hold a pointer to the global data 4665 4666 Note: on PPC, we could use a static initializer (since the 4667 address of the global data structure is known at compile time), 4668 but it turned out that reserving a register results in somewhat 4669 smaller code - although the code savings are not that big (on 4670 average for all boards 752 bytes for the whole U-Boot image, 4671 624 text + 127 data). 4672 4673On ARM, the following registers are used: 4674 4675 R0: function argument word/integer result 4676 R1-R3: function argument word 4677 R9: platform specific 4678 R10: stack limit (used only if stack checking is enabled) 4679 R11: argument (frame) pointer 4680 R12: temporary workspace 4681 R13: stack pointer 4682 R14: link register 4683 R15: program counter 4684 4685 ==> U-Boot will use R9 to hold a pointer to the global data 4686 4687 Note: on ARM, only R_ARM_RELATIVE relocations are supported. 4688 4689On Nios II, the ABI is documented here: 4690 http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf 4691 4692 ==> U-Boot will use gp to hold a pointer to the global data 4693 4694 Note: on Nios II, we give "-G0" option to gcc and don't use gp 4695 to access small data sections, so gp is free. 4696 4697On NDS32, the following registers are used: 4698 4699 R0-R1: argument/return 4700 R2-R5: argument 4701 R15: temporary register for assembler 4702 R16: trampoline register 4703 R28: frame pointer (FP) 4704 R29: global pointer (GP) 4705 R30: link register (LP) 4706 R31: stack pointer (SP) 4707 PC: program counter (PC) 4708 4709 ==> U-Boot will use R10 to hold a pointer to the global data 4710 4711NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope, 4712or current versions of GCC may "optimize" the code too much. 4713 4714On RISC-V, the following registers are used: 4715 4716 x0: hard-wired zero (zero) 4717 x1: return address (ra) 4718 x2: stack pointer (sp) 4719 x3: global pointer (gp) 4720 x4: thread pointer (tp) 4721 x5: link register (t0) 4722 x8: frame pointer (fp) 4723 x10-x11: arguments/return values (a0-1) 4724 x12-x17: arguments (a2-7) 4725 x28-31: temporaries (t3-6) 4726 pc: program counter (pc) 4727 4728 ==> U-Boot will use gp to hold a pointer to the global data 4729 4730Memory Management: 4731------------------ 4732 4733U-Boot runs in system state and uses physical addresses, i.e. the 4734MMU is not used either for address mapping nor for memory protection. 4735 4736The available memory is mapped to fixed addresses using the memory 4737controller. In this process, a contiguous block is formed for each 4738memory type (Flash, SDRAM, SRAM), even when it consists of several 4739physical memory banks. 4740 4741U-Boot is installed in the first 128 kB of the first Flash bank (on 4742TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After 4743booting and sizing and initializing DRAM, the code relocates itself 4744to the upper end of DRAM. Immediately below the U-Boot code some 4745memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN 4746configuration setting]. Below that, a structure with global Board 4747Info data is placed, followed by the stack (growing downward). 4748 4749Additionally, some exception handler code is copied to the low 8 kB 4750of DRAM (0x00000000 ... 0x00001FFF). 4751 4752So a typical memory configuration with 16 MB of DRAM could look like 4753this: 4754 4755 0x0000 0000 Exception Vector code 4756 : 4757 0x0000 1FFF 4758 0x0000 2000 Free for Application Use 4759 : 4760 : 4761 4762 : 4763 : 4764 0x00FB FF20 Monitor Stack (Growing downward) 4765 0x00FB FFAC Board Info Data and permanent copy of global data 4766 0x00FC 0000 Malloc Arena 4767 : 4768 0x00FD FFFF 4769 0x00FE 0000 RAM Copy of Monitor Code 4770 ... eventually: LCD or video framebuffer 4771 ... eventually: pRAM (Protected RAM - unchanged by reset) 4772 0x00FF FFFF [End of RAM] 4773 4774 4775System Initialization: 4776---------------------- 4777 4778In the reset configuration, U-Boot starts at the reset entry point 4779(on most PowerPC systems at address 0x00000100). Because of the reset 4780configuration for CS0# this is a mirror of the on board Flash memory. 4781To be able to re-map memory U-Boot then jumps to its link address. 4782To be able to implement the initialization code in C, a (small!) 4783initial stack is set up in the internal Dual Ported RAM (in case CPUs 4784which provide such a feature like), or in a locked part of the data 4785cache. After that, U-Boot initializes the CPU core, the caches and 4786the SIU. 4787 4788Next, all (potentially) available memory banks are mapped using a 4789preliminary mapping. For example, we put them on 512 MB boundaries 4790(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash 4791on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is 4792programmed for SDRAM access. Using the temporary configuration, a 4793simple memory test is run that determines the size of the SDRAM 4794banks. 4795 4796When there is more than one SDRAM bank, and the banks are of 4797different size, the largest is mapped first. For equal size, the first 4798bank (CS2#) is mapped first. The first mapping is always for address 47990x00000000, with any additional banks following immediately to create 4800contiguous memory starting from 0. 4801 4802Then, the monitor installs itself at the upper end of the SDRAM area 4803and allocates memory for use by malloc() and for the global Board 4804Info data; also, the exception vector code is copied to the low RAM 4805pages, and the final stack is set up. 4806 4807Only after this relocation will you have a "normal" C environment; 4808until that you are restricted in several ways, mostly because you are 4809running from ROM, and because the code will have to be relocated to a 4810new address in RAM. 4811 4812 4813U-Boot Porting Guide: 4814---------------------- 4815 4816[Based on messages by Jerry Van Baren in the U-Boot-Users mailing 4817list, October 2002] 4818 4819 4820int main(int argc, char *argv[]) 4821{ 4822 sighandler_t no_more_time; 4823 4824 signal(SIGALRM, no_more_time); 4825 alarm(PROJECT_DEADLINE - toSec (3 * WEEK)); 4826 4827 if (available_money > available_manpower) { 4828 Pay consultant to port U-Boot; 4829 return 0; 4830 } 4831 4832 Download latest U-Boot source; 4833 4834 Subscribe to u-boot mailing list; 4835 4836 if (clueless) 4837 email("Hi, I am new to U-Boot, how do I get started?"); 4838 4839 while (learning) { 4840 Read the README file in the top level directory; 4841 Read http://www.denx.de/twiki/bin/view/DULG/Manual; 4842 Read applicable doc/*.README; 4843 Read the source, Luke; 4844 /* find . -name "*.[chS]" | xargs grep -i <keyword> */ 4845 } 4846 4847 if (available_money > toLocalCurrency ($2500)) 4848 Buy a BDI3000; 4849 else 4850 Add a lot of aggravation and time; 4851 4852 if (a similar board exists) { /* hopefully... */ 4853 cp -a board/<similar> board/<myboard> 4854 cp include/configs/<similar>.h include/configs/<myboard>.h 4855 } else { 4856 Create your own board support subdirectory; 4857 Create your own board include/configs/<myboard>.h file; 4858 } 4859 Edit new board/<myboard> files 4860 Edit new include/configs/<myboard>.h 4861 4862 while (!accepted) { 4863 while (!running) { 4864 do { 4865 Add / modify source code; 4866 } until (compiles); 4867 Debug; 4868 if (clueless) 4869 email("Hi, I am having problems..."); 4870 } 4871 Send patch file to the U-Boot email list; 4872 if (reasonable critiques) 4873 Incorporate improvements from email list code review; 4874 else 4875 Defend code as written; 4876 } 4877 4878 return 0; 4879} 4880 4881void no_more_time (int sig) 4882{ 4883 hire_a_guru(); 4884} 4885 4886 4887Coding Standards: 4888----------------- 4889 4890All contributions to U-Boot should conform to the Linux kernel 4891coding style; see the kernel coding style guide at 4892https://www.kernel.org/doc/html/latest/process/coding-style.html, and the 4893script "scripts/Lindent" in your Linux kernel source directory. 4894 4895Source files originating from a different project (for example the 4896MTD subsystem) are generally exempt from these guidelines and are not 4897reformatted to ease subsequent migration to newer versions of those 4898sources. 4899 4900Please note that U-Boot is implemented in C (and to some small parts in 4901Assembler); no C++ is used, so please do not use C++ style comments (//) 4902in your code. 4903 4904Please also stick to the following formatting rules: 4905- remove any trailing white space 4906- use TAB characters for indentation and vertical alignment, not spaces 4907- make sure NOT to use DOS '\r\n' line feeds 4908- do not add more than 2 consecutive empty lines to source files 4909- do not add trailing empty lines to source files 4910 4911Submissions which do not conform to the standards may be returned 4912with a request to reformat the changes. 4913 4914 4915Submitting Patches: 4916------------------- 4917 4918Since the number of patches for U-Boot is growing, we need to 4919establish some rules. Submissions which do not conform to these rules 4920may be rejected, even when they contain important and valuable stuff. 4921 4922Please see http://www.denx.de/wiki/U-Boot/Patches for details. 4923 4924Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>; 4925see https://lists.denx.de/listinfo/u-boot 4926 4927When you send a patch, please include the following information with 4928it: 4929 4930* For bug fixes: a description of the bug and how your patch fixes 4931 this bug. Please try to include a way of demonstrating that the 4932 patch actually fixes something. 4933 4934* For new features: a description of the feature and your 4935 implementation. 4936 4937* A CHANGELOG entry as plaintext (separate from the patch) 4938 4939* For major contributions, add a MAINTAINERS file with your 4940 information and associated file and directory references. 4941 4942* When you add support for a new board, don't forget to add a 4943 maintainer e-mail address to the boards.cfg file, too. 4944 4945* If your patch adds new configuration options, don't forget to 4946 document these in the README file. 4947 4948* The patch itself. If you are using git (which is *strongly* 4949 recommended) you can easily generate the patch using the 4950 "git format-patch". If you then use "git send-email" to send it to 4951 the U-Boot mailing list, you will avoid most of the common problems 4952 with some other mail clients. 4953 4954 If you cannot use git, use "diff -purN OLD NEW". If your version of 4955 diff does not support these options, then get the latest version of 4956 GNU diff. 4957 4958 The current directory when running this command shall be the parent 4959 directory of the U-Boot source tree (i. e. please make sure that 4960 your patch includes sufficient directory information for the 4961 affected files). 4962 4963 We prefer patches as plain text. MIME attachments are discouraged, 4964 and compressed attachments must not be used. 4965 4966* If one logical set of modifications affects or creates several 4967 files, all these changes shall be submitted in a SINGLE patch file. 4968 4969* Changesets that contain different, unrelated modifications shall be 4970 submitted as SEPARATE patches, one patch per changeset. 4971 4972 4973Notes: 4974 4975* Before sending the patch, run the buildman script on your patched 4976 source tree and make sure that no errors or warnings are reported 4977 for any of the boards. 4978 4979* Keep your modifications to the necessary minimum: A patch 4980 containing several unrelated changes or arbitrary reformats will be 4981 returned with a request to re-formatting / split it. 4982 4983* If you modify existing code, make sure that your new code does not 4984 add to the memory footprint of the code ;-) Small is beautiful! 4985 When adding new features, these should compile conditionally only 4986 (using #ifdef), and the resulting code with the new feature 4987 disabled must not need more memory than the old code without your 4988 modification. 4989 4990* Remember that there is a size limit of 100 kB per message on the 4991 u-boot mailing list. Bigger patches will be moderated. If they are 4992 reasonable and not too big, they will be acknowledged. But patches 4993 bigger than the size limit should be avoided. 4994