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 https://lists.denx.de/pipermail/u-boot and 55https://marc.info/?l=u-boot 56 57Where to get source code: 58========================= 59 60The U-Boot source code is maintained in the Git repository at 61https://source.denx.de/u-boot/u-boot.git ; you can browse it online at 62https://source.denx.de/u-boot/u-boot 63 64The "Tags" links on this page allow you to download tarballs of 65any version you might be interested in. Official releases are also 66available from the DENX file server through HTTPS or FTP. 67https://ftp.denx.de/pub/u-boot/ 68ftp://ftp.denx.de/pub/u-boot/ 69 70 71Where we come from: 72=================== 73 74- start from 8xxrom sources 75- create PPCBoot project (https://sourceforge.net/projects/ppcboot) 76- clean up code 77- make it easier to add custom boards 78- make it possible to add other [PowerPC] CPUs 79- extend functions, especially: 80 * Provide extended interface to Linux boot loader 81 * S-Record download 82 * network boot 83 * ATA disk / SCSI ... boot 84- create ARMBoot project (https://sourceforge.net/projects/armboot) 85- add other CPU families (starting with ARM) 86- create U-Boot project (https://sourceforge.net/projects/u-boot) 87- current project page: see https://www.denx.de/wiki/U-Boot 88 89 90Names and Spelling: 91=================== 92 93The "official" name of this project is "Das U-Boot". The spelling 94"U-Boot" shall be used in all written text (documentation, comments 95in source files etc.). Example: 96 97 This is the README file for the U-Boot project. 98 99File names etc. shall be based on the string "u-boot". Examples: 100 101 include/asm-ppc/u-boot.h 102 103 #include <asm/u-boot.h> 104 105Variable names, preprocessor constants etc. shall be either based on 106the string "u_boot" or on "U_BOOT". Example: 107 108 U_BOOT_VERSION u_boot_logo 109 IH_OS_U_BOOT u_boot_hush_start 110 111 112Versioning: 113=========== 114 115Starting with the release in October 2008, the names of the releases 116were changed from numerical release numbers without deeper meaning 117into a time stamp based numbering. Regular releases are identified by 118names consisting of the calendar year and month of the release date. 119Additional fields (if present) indicate release candidates or bug fix 120releases in "stable" maintenance trees. 121 122Examples: 123 U-Boot v2009.11 - Release November 2009 124 U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree 125 U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release 126 127 128Directory Hierarchy: 129==================== 130 131/arch Architecture-specific files 132 /arc Files generic to ARC architecture 133 /arm Files generic to ARM architecture 134 /m68k Files generic to m68k architecture 135 /microblaze Files generic to microblaze architecture 136 /mips Files generic to MIPS architecture 137 /nds32 Files generic to NDS32 architecture 138 /nios2 Files generic to Altera NIOS2 architecture 139 /powerpc Files generic to PowerPC architecture 140 /riscv Files generic to RISC-V architecture 141 /sandbox Files generic to HW-independent "sandbox" 142 /sh Files generic to SH architecture 143 /x86 Files generic to x86 architecture 144 /xtensa Files generic to Xtensa architecture 145/api Machine/arch-independent API for external apps 146/board Board-dependent files 147/boot Support for images and booting 148/cmd U-Boot commands functions 149/common Misc architecture-independent functions 150/configs Board default configuration files 151/disk Code for disk drive partition handling 152/doc Documentation (a mix of ReST and READMEs) 153/drivers Device drivers 154/dts Makefile for building internal U-Boot fdt. 155/env Environment support 156/examples Example code for standalone applications, etc. 157/fs Filesystem code (cramfs, ext2, jffs2, etc.) 158/include Header Files 159/lib Library routines generic to all architectures 160/Licenses Various license files 161/net Networking code 162/post Power On Self Test 163/scripts Various build scripts and Makefiles 164/test Various unit test files 165/tools Tools to build and sign FIT images, etc. 166 167Software Configuration: 168======================= 169 170Configuration is usually done using C preprocessor defines; the 171rationale behind that is to avoid dead code whenever possible. 172 173There are two classes of configuration variables: 174 175* Configuration _OPTIONS_: 176 These are selectable by the user and have names beginning with 177 "CONFIG_". 178 179* Configuration _SETTINGS_: 180 These depend on the hardware etc. and should not be meddled with if 181 you don't know what you're doing; they have names beginning with 182 "CONFIG_SYS_". 183 184Previously, all configuration was done by hand, which involved creating 185symbolic links and editing configuration files manually. More recently, 186U-Boot has added the Kbuild infrastructure used by the Linux kernel, 187allowing you to use the "make menuconfig" command to configure your 188build. 189 190 191Selection of Processor Architecture and Board Type: 192--------------------------------------------------- 193 194For all supported boards there are ready-to-use default 195configurations available; just type "make <board_name>_defconfig". 196 197Example: For a TQM823L module type: 198 199 cd u-boot 200 make TQM823L_defconfig 201 202Note: If you're looking for the default configuration file for a board 203you're sure used to be there but is now missing, check the file 204doc/README.scrapyard for a list of no longer supported boards. 205 206Sandbox Environment: 207-------------------- 208 209U-Boot can be built natively to run on a Linux host using the 'sandbox' 210board. This allows feature development which is not board- or architecture- 211specific to be undertaken on a native platform. The sandbox is also used to 212run some of U-Boot's tests. 213 214See doc/arch/sandbox.rst for more details. 215 216 217Board Initialisation Flow: 218-------------------------- 219 220This is the intended start-up flow for boards. This should apply for both 221SPL and U-Boot proper (i.e. they both follow the same rules). 222 223Note: "SPL" stands for "Secondary Program Loader," which is explained in 224more detail later in this file. 225 226At present, SPL mostly uses a separate code path, but the function names 227and roles of each function are the same. Some boards or architectures 228may not conform to this. At least most ARM boards which use 229CONFIG_SPL_FRAMEWORK conform to this. 230 231Execution typically starts with an architecture-specific (and possibly 232CPU-specific) start.S file, such as: 233 234 - arch/arm/cpu/armv7/start.S 235 - arch/powerpc/cpu/mpc83xx/start.S 236 - arch/mips/cpu/start.S 237 238and so on. From there, three functions are called; the purpose and 239limitations of each of these functions are described below. 240 241lowlevel_init(): 242 - purpose: essential init to permit execution to reach board_init_f() 243 - no global_data or BSS 244 - there is no stack (ARMv7 may have one but it will soon be removed) 245 - must not set up SDRAM or use console 246 - must only do the bare minimum to allow execution to continue to 247 board_init_f() 248 - this is almost never needed 249 - return normally from this function 250 251board_init_f(): 252 - purpose: set up the machine ready for running board_init_r(): 253 i.e. SDRAM and serial UART 254 - global_data is available 255 - stack is in SRAM 256 - BSS is not available, so you cannot use global/static variables, 257 only stack variables and global_data 258 259 Non-SPL-specific notes: 260 - dram_init() is called to set up DRAM. If already done in SPL this 261 can do nothing 262 263 SPL-specific notes: 264 - you can override the entire board_init_f() function with your own 265 version as needed. 266 - preloader_console_init() can be called here in extremis 267 - should set up SDRAM, and anything needed to make the UART work 268 - there is no need to clear BSS, it will be done by crt0.S 269 - for specific scenarios on certain architectures an early BSS *can* 270 be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing 271 of BSS prior to entering board_init_f()) but doing so is discouraged. 272 Instead it is strongly recommended to architect any code changes 273 or additions such to not depend on the availability of BSS during 274 board_init_f() as indicated in other sections of this README to 275 maintain compatibility and consistency across the entire code base. 276 - must return normally from this function (don't call board_init_r() 277 directly) 278 279Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at 280this point the stack and global_data are relocated to below 281CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of 282memory. 283 284board_init_r(): 285 - purpose: main execution, common code 286 - global_data is available 287 - SDRAM is available 288 - BSS is available, all static/global variables can be used 289 - execution eventually continues to main_loop() 290 291 Non-SPL-specific notes: 292 - U-Boot is relocated to the top of memory and is now running from 293 there. 294 295 SPL-specific notes: 296 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and 297 CONFIG_SPL_STACK_R_ADDR points into SDRAM 298 - preloader_console_init() can be called here - typically this is 299 done by selecting CONFIG_SPL_BOARD_INIT and then supplying a 300 spl_board_init() function containing this call 301 - loads U-Boot or (in falcon mode) Linux 302 303 304Configuration Options: 305---------------------- 306 307Configuration depends on the combination of board and CPU type; all 308such information is kept in a configuration file 309"include/configs/<board_name>.h". 310 311Example: For a TQM823L module, all configuration settings are in 312"include/configs/TQM823L.h". 313 314 315Many of the options are named exactly as the corresponding Linux 316kernel configuration options. The intention is to make it easier to 317build a config tool - later. 318 319- ARM Platform Bus Type(CCI): 320 CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which 321 provides full cache coherency between two clusters of multi-core 322 CPUs and I/O coherency for devices and I/O masters 323 324 CONFIG_SYS_FSL_HAS_CCI400 325 326 Defined For SoC that has cache coherent interconnect 327 CCN-400 328 329 CONFIG_SYS_FSL_HAS_CCN504 330 331 Defined for SoC that has cache coherent interconnect CCN-504 332 333The following options need to be configured: 334 335- CPU Type: Define exactly one, e.g. CONFIG_MPC85XX. 336 337- Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS. 338 339- 85xx CPU Options: 340 CONFIG_SYS_PPC64 341 342 Specifies that the core is a 64-bit PowerPC implementation (implements 343 the "64" category of the Power ISA). This is necessary for ePAPR 344 compliance, among other possible reasons. 345 346 CONFIG_SYS_FSL_TBCLK_DIV 347 348 Defines the core time base clock divider ratio compared to the 349 system clock. On most PQ3 devices this is 8, on newer QorIQ 350 devices it can be 16 or 32. The ratio varies from SoC to Soc. 351 352 CONFIG_SYS_FSL_PCIE_COMPAT 353 354 Defines the string to utilize when trying to match PCIe device 355 tree nodes for the given platform. 356 357 CONFIG_SYS_FSL_ERRATUM_A004510 358 359 Enables a workaround for erratum A004510. If set, 360 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and 361 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set. 362 363 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV 364 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional) 365 366 Defines one or two SoC revisions (low 8 bits of SVR) 367 for which the A004510 workaround should be applied. 368 369 The rest of SVR is either not relevant to the decision 370 of whether the erratum is present (e.g. p2040 versus 371 p2041) or is implied by the build target, which controls 372 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set. 373 374 See Freescale App Note 4493 for more information about 375 this erratum. 376 377 CONFIG_A003399_NOR_WORKAROUND 378 Enables a workaround for IFC erratum A003399. It is only 379 required during NOR boot. 380 381 CONFIG_A008044_WORKAROUND 382 Enables a workaround for T1040/T1042 erratum A008044. It is only 383 required during NAND boot and valid for Rev 1.0 SoC revision 384 385 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY 386 387 This is the value to write into CCSR offset 0x18600 388 according to the A004510 workaround. 389 390 CONFIG_SYS_FSL_DSP_DDR_ADDR 391 This value denotes start offset of DDR memory which is 392 connected exclusively to the DSP cores. 393 394 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR 395 This value denotes start offset of M2 memory 396 which is directly connected to the DSP core. 397 398 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR 399 This value denotes start offset of M3 memory which is directly 400 connected to the DSP core. 401 402 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT 403 This value denotes start offset of DSP CCSR space. 404 405 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK 406 Single Source Clock is clocking mode present in some of FSL SoC's. 407 In this mode, a single differential clock is used to supply 408 clocks to the sysclock, ddrclock and usbclock. 409 410 CONFIG_SYS_CPC_REINIT_F 411 This CONFIG is defined when the CPC is configured as SRAM at the 412 time of U-Boot entry and is required to be re-initialized. 413 414 CONFIG_DEEP_SLEEP 415 Indicates this SoC supports deep sleep feature. If deep sleep is 416 supported, core will start to execute uboot when wakes up. 417 418- Generic CPU options: 419 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN 420 421 Defines the endianess of the CPU. Implementation of those 422 values is arch specific. 423 424 CONFIG_SYS_FSL_DDR 425 Freescale DDR driver in use. This type of DDR controller is 426 found in mpc83xx, mpc85xx as well as some ARM core SoCs. 427 428 CONFIG_SYS_FSL_DDR_ADDR 429 Freescale DDR memory-mapped register base. 430 431 CONFIG_SYS_FSL_DDR_EMU 432 Specify emulator support for DDR. Some DDR features such as 433 deskew training are not available. 434 435 CONFIG_SYS_FSL_DDRC_GEN1 436 Freescale DDR1 controller. 437 438 CONFIG_SYS_FSL_DDRC_GEN2 439 Freescale DDR2 controller. 440 441 CONFIG_SYS_FSL_DDRC_GEN3 442 Freescale DDR3 controller. 443 444 CONFIG_SYS_FSL_DDRC_GEN4 445 Freescale DDR4 controller. 446 447 CONFIG_SYS_FSL_DDRC_ARM_GEN3 448 Freescale DDR3 controller for ARM-based SoCs. 449 450 CONFIG_SYS_FSL_DDR1 451 Board config to use DDR1. It can be enabled for SoCs with 452 Freescale DDR1 or DDR2 controllers, depending on the board 453 implemetation. 454 455 CONFIG_SYS_FSL_DDR2 456 Board config to use DDR2. It can be enabled for SoCs with 457 Freescale DDR2 or DDR3 controllers, depending on the board 458 implementation. 459 460 CONFIG_SYS_FSL_DDR3 461 Board config to use DDR3. It can be enabled for SoCs with 462 Freescale DDR3 or DDR3L controllers. 463 464 CONFIG_SYS_FSL_DDR3L 465 Board config to use DDR3L. It can be enabled for SoCs with 466 DDR3L 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_DDR_BE 481 Defines the DDR controller register space as Big Endian 482 483 CONFIG_SYS_FSL_DDR_LE 484 Defines the DDR controller register space as Little Endian 485 486 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY 487 Physical address from the view of DDR controllers. It is the 488 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But 489 it could be different for ARM SoCs. 490 491 CONFIG_SYS_FSL_DDR_INTLV_256B 492 DDR controller interleaving on 256-byte. This is a special 493 interleaving mode, handled by Dickens for Freescale layerscape 494 SoCs with ARM core. 495 496 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS 497 Number of controllers used as main memory. 498 499 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS 500 Number of controllers used for other than main memory. 501 502 CONFIG_SYS_FSL_HAS_DP_DDR 503 Defines the SoC has DP-DDR used for DPAA. 504 505 CONFIG_SYS_FSL_SEC_BE 506 Defines the SEC controller register space as Big Endian 507 508 CONFIG_SYS_FSL_SEC_LE 509 Defines the SEC controller register space as Little Endian 510 511- MIPS CPU options: 512 CONFIG_SYS_INIT_SP_OFFSET 513 514 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack 515 pointer. This is needed for the temporary stack before 516 relocation. 517 518 CONFIG_XWAY_SWAP_BYTES 519 520 Enable compilation of tools/xway-swap-bytes needed for Lantiq 521 XWAY SoCs for booting from NOR flash. The U-Boot image needs to 522 be swapped if a flash programmer is used. 523 524- ARM options: 525 CONFIG_SYS_EXCEPTION_VECTORS_HIGH 526 527 Select high exception vectors of the ARM core, e.g., do not 528 clear the V bit of the c1 register of CP15. 529 530 COUNTER_FREQUENCY 531 Generic timer clock source frequency. 532 533 COUNTER_FREQUENCY_REAL 534 Generic timer clock source frequency if the real clock is 535 different from COUNTER_FREQUENCY, and can only be determined 536 at run time. 537 538- Tegra SoC options: 539 CONFIG_TEGRA_SUPPORT_NON_SECURE 540 541 Support executing U-Boot in non-secure (NS) mode. Certain 542 impossible actions will be skipped if the CPU is in NS mode, 543 such as ARM architectural timer initialization. 544 545- Linux Kernel Interface: 546 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only] 547 548 When transferring memsize parameter to Linux, some versions 549 expect it to be in bytes, others in MB. 550 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes. 551 552 CONFIG_OF_LIBFDT 553 554 New kernel versions are expecting firmware settings to be 555 passed using flattened device trees (based on open firmware 556 concepts). 557 558 CONFIG_OF_LIBFDT 559 * New libfdt-based support 560 * Adds the "fdt" command 561 * The bootm command automatically updates the fdt 562 563 OF_TBCLK - The timebase frequency. 564 565 boards with QUICC Engines require OF_QE to set UCC MAC 566 addresses 567 568 CONFIG_OF_BOARD_SETUP 569 570 Board code has addition modification that it wants to make 571 to the flat device tree before handing it off to the kernel 572 573 CONFIG_OF_SYSTEM_SETUP 574 575 Other code has addition modification that it wants to make 576 to the flat device tree before handing it off to the kernel. 577 This causes ft_system_setup() to be called before booting 578 the kernel. 579 580 CONFIG_OF_IDE_FIXUP 581 582 U-Boot can detect if an IDE device is present or not. 583 If not, and this new config option is activated, U-Boot 584 removes the ATA node from the DTS before booting Linux, 585 so the Linux IDE driver does not probe the device and 586 crash. This is needed for buggy hardware (uc101) where 587 no pull down resistor is connected to the signal IDE5V_DD7. 588 589- vxWorks boot parameters: 590 591 bootvx constructs a valid bootline using the following 592 environments variables: bootdev, bootfile, ipaddr, netmask, 593 serverip, gatewayip, hostname, othbootargs. 594 It loads the vxWorks image pointed bootfile. 595 596 Note: If a "bootargs" environment is defined, it will override 597 the defaults discussed just above. 598 599- Cache Configuration: 600 CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot 601 602- Cache Configuration for ARM: 603 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache 604 controller 605 CONFIG_SYS_PL310_BASE - Physical base address of PL310 606 controller register space 607 608- Serial Ports: 609 CONFIG_PL011_CLOCK 610 611 If you have Amba PrimeCell PL011 UARTs, set this variable to 612 the clock speed of the UARTs. 613 614 CONFIG_PL01x_PORTS 615 616 If you have Amba PrimeCell PL010 or PL011 UARTs on your board, 617 define this to a list of base addresses for each (supported) 618 port. See e.g. include/configs/versatile.h 619 620 CONFIG_SERIAL_HW_FLOW_CONTROL 621 622 Define this variable to enable hw flow control in serial driver. 623 Current user of this option is drivers/serial/nsl16550.c driver 624 625- Autoboot Command: 626 CONFIG_BOOTCOMMAND 627 Only needed when CONFIG_BOOTDELAY is enabled; 628 define a command string that is automatically executed 629 when no character is read on the console interface 630 within "Boot Delay" after reset. 631 632 CONFIG_RAMBOOT and CONFIG_NFSBOOT 633 The value of these goes into the environment as 634 "ramboot" and "nfsboot" respectively, and can be used 635 as a convenience, when switching between booting from 636 RAM and NFS. 637 638- Serial Download Echo Mode: 639 CONFIG_LOADS_ECHO 640 If defined to 1, all characters received during a 641 serial download (using the "loads" command) are 642 echoed back. This might be needed by some terminal 643 emulations (like "cu"), but may as well just take 644 time on others. This setting #define's the initial 645 value of the "loads_echo" environment variable. 646 647- Removal of commands 648 If no commands are needed to boot, you can disable 649 CONFIG_CMDLINE to remove them. In this case, the command line 650 will not be available, and when U-Boot wants to execute the 651 boot command (on start-up) it will call board_run_command() 652 instead. This can reduce image size significantly for very 653 simple boot procedures. 654 655- Regular expression support: 656 CONFIG_REGEX 657 If this variable is defined, U-Boot is linked against 658 the SLRE (Super Light Regular Expression) library, 659 which adds regex support to some commands, as for 660 example "env grep" and "setexpr". 661 662- Device tree: 663 CONFIG_OF_CONTROL 664 If this variable is defined, U-Boot will use a device tree 665 to configure its devices, instead of relying on statically 666 compiled #defines in the board file. This option is 667 experimental and only available on a few boards. The device 668 tree is available in the global data as gd->fdt_blob. 669 670 U-Boot needs to get its device tree from somewhere. This can 671 be done using one of the three options below: 672 673 CONFIG_OF_SEPARATE 674 If this variable is defined, U-Boot will build a device tree 675 binary. It will be called u-boot.dtb. Architecture-specific 676 code will locate it at run-time. Generally this works by: 677 678 cat u-boot.bin u-boot.dtb >image.bin 679 680 and in fact, U-Boot does this for you, creating a file called 681 u-boot-dtb.bin which is useful in the common case. You can 682 still use the individual files if you need something more 683 exotic. 684 685 CONFIG_OF_BOARD 686 If this variable is defined, U-Boot will use the device tree 687 provided by the board at runtime instead of embedding one with 688 the image. Only boards defining board_fdt_blob_setup() support 689 this option (see include/fdtdec.h file). 690 691- Watchdog: 692 CONFIG_WATCHDOG 693 If this variable is defined, it enables watchdog 694 support for the SoC. There must be support in the SoC 695 specific code for a watchdog. For the 8xx 696 CPUs, the SIU Watchdog feature is enabled in the SYPCR 697 register. When supported for a specific SoC is 698 available, then no further board specific code should 699 be needed to use it. 700 701 CONFIG_HW_WATCHDOG 702 When using a watchdog circuitry external to the used 703 SoC, then define this variable and provide board 704 specific code for the "hw_watchdog_reset" function. 705 706 CONFIG_SYS_WATCHDOG_FREQ 707 Some platforms automatically call WATCHDOG_RESET() 708 from the timer interrupt handler every 709 CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the 710 board configuration file, a default of CONFIG_SYS_HZ/2 711 (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ 712 to 0 disables calling WATCHDOG_RESET() from the timer 713 interrupt. 714 715- Real-Time Clock: 716 717 When CONFIG_CMD_DATE is selected, the type of the RTC 718 has to be selected, too. Define exactly one of the 719 following options: 720 721 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC 722 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC 723 CONFIG_RTC_MC146818 - use MC146818 RTC 724 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC 725 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC 726 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC 727 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC 728 CONFIG_RTC_DS164x - use Dallas DS164x RTC 729 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC 730 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC 731 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337 732 CONFIG_SYS_RV3029_TCR - enable trickle charger on 733 RV3029 RTC. 734 735 Note that if the RTC uses I2C, then the I2C interface 736 must also be configured. See I2C Support, below. 737 738- GPIO Support: 739 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO 740 741 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of 742 chip-ngpio pairs that tell the PCA953X driver the number of 743 pins supported by a particular chip. 744 745 Note that if the GPIO device uses I2C, then the I2C interface 746 must also be configured. See I2C Support, below. 747 748- I/O tracing: 749 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O 750 accesses and can checksum them or write a list of them out 751 to memory. See the 'iotrace' command for details. This is 752 useful for testing device drivers since it can confirm that 753 the driver behaves the same way before and after a code 754 change. Currently this is supported on sandbox and arm. To 755 add support for your architecture, add '#include <iotrace.h>' 756 to the bottom of arch/<arch>/include/asm/io.h and test. 757 758 Example output from the 'iotrace stats' command is below. 759 Note that if the trace buffer is exhausted, the checksum will 760 still continue to operate. 761 762 iotrace is enabled 763 Start: 10000000 (buffer start address) 764 Size: 00010000 (buffer size) 765 Offset: 00000120 (current buffer offset) 766 Output: 10000120 (start + offset) 767 Count: 00000018 (number of trace records) 768 CRC32: 9526fb66 (CRC32 of all trace records) 769 770- Timestamp Support: 771 772 When CONFIG_TIMESTAMP is selected, the timestamp 773 (date and time) of an image is printed by image 774 commands like bootm or iminfo. This option is 775 automatically enabled when you select CONFIG_CMD_DATE . 776 777- Partition Labels (disklabels) Supported: 778 Zero or more of the following: 779 CONFIG_MAC_PARTITION Apple's MacOS partition table. 780 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc. 781 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the 782 bootloader. Note 2TB partition limit; see 783 disk/part_efi.c 784 CONFIG_SCSI) you must configure support for at 785 least one non-MTD partition type as well. 786 787- IDE Reset method: 788 CONFIG_IDE_RESET_ROUTINE - this is defined in several 789 board configurations files but used nowhere! 790 791 CONFIG_IDE_RESET - is this is defined, IDE Reset will 792 be performed by calling the function 793 ide_set_reset(int reset) 794 which has to be defined in a board specific file 795 796- ATAPI Support: 797 CONFIG_ATAPI 798 799 Set this to enable ATAPI support. 800 801- LBA48 Support 802 CONFIG_LBA48 803 804 Set this to enable support for disks larger than 137GB 805 Also look at CONFIG_SYS_64BIT_LBA. 806 Whithout these , LBA48 support uses 32bit variables and will 'only' 807 support disks up to 2.1TB. 808 809 CONFIG_SYS_64BIT_LBA: 810 When enabled, makes the IDE subsystem use 64bit sector addresses. 811 Default is 32bit. 812 813- SCSI Support: 814 CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and 815 CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID * 816 CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the 817 maximum numbers of LUNs, SCSI ID's and target 818 devices. 819 820 The environment variable 'scsidevs' is set to the number of 821 SCSI devices found during the last scan. 822 823- NETWORK Support (PCI): 824 CONFIG_E1000_SPI 825 Utility code for direct access to the SPI bus on Intel 8257x. 826 This does not do anything useful unless you set at least one 827 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC. 828 829 CONFIG_NATSEMI 830 Support for National dp83815 chips. 831 832 CONFIG_NS8382X 833 Support for National dp8382[01] gigabit chips. 834 835- NETWORK Support (other): 836 CONFIG_CALXEDA_XGMAC 837 Support for the Calxeda XGMAC device 838 839 CONFIG_LAN91C96 840 Support for SMSC's LAN91C96 chips. 841 842 CONFIG_LAN91C96_USE_32_BIT 843 Define this to enable 32 bit addressing 844 845 CONFIG_SMC91111 846 Support for SMSC's LAN91C111 chip 847 848 CONFIG_SMC91111_BASE 849 Define this to hold the physical address 850 of the device (I/O space) 851 852 CONFIG_SMC_USE_32_BIT 853 Define this if data bus is 32 bits 854 855 CONFIG_SMC_USE_IOFUNCS 856 Define this to use i/o functions instead of macros 857 (some hardware wont work with macros) 858 859 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT 860 Define this if you have more then 3 PHYs. 861 862 CONFIG_FTGMAC100 863 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet 864 865 CONFIG_FTGMAC100_EGIGA 866 Define this to use GE link update with gigabit PHY. 867 Define this if FTGMAC100 is connected to gigabit PHY. 868 If your system has 10/100 PHY only, it might not occur 869 wrong behavior. Because PHY usually return timeout or 870 useless data when polling gigabit status and gigabit 871 control registers. This behavior won't affect the 872 correctnessof 10/100 link speed update. 873 874 CONFIG_SH_ETHER 875 Support for Renesas on-chip Ethernet controller 876 877 CONFIG_SH_ETHER_USE_PORT 878 Define the number of ports to be used 879 880 CONFIG_SH_ETHER_PHY_ADDR 881 Define the ETH PHY's address 882 883 CONFIG_SH_ETHER_CACHE_WRITEBACK 884 If this option is set, the driver enables cache flush. 885 886- TPM Support: 887 CONFIG_TPM 888 Support TPM devices. 889 890 CONFIG_TPM_TIS_INFINEON 891 Support for Infineon i2c bus TPM devices. Only one device 892 per system is supported at this time. 893 894 CONFIG_TPM_TIS_I2C_BURST_LIMITATION 895 Define the burst count bytes upper limit 896 897 CONFIG_TPM_ST33ZP24 898 Support for STMicroelectronics TPM devices. Requires DM_TPM support. 899 900 CONFIG_TPM_ST33ZP24_I2C 901 Support for STMicroelectronics ST33ZP24 I2C devices. 902 Requires TPM_ST33ZP24 and I2C. 903 904 CONFIG_TPM_ST33ZP24_SPI 905 Support for STMicroelectronics ST33ZP24 SPI devices. 906 Requires TPM_ST33ZP24 and SPI. 907 908 CONFIG_TPM_ATMEL_TWI 909 Support for Atmel TWI TPM device. Requires I2C support. 910 911 CONFIG_TPM_TIS_LPC 912 Support for generic parallel port TPM devices. Only one device 913 per system is supported at this time. 914 915 CONFIG_TPM_TIS_BASE_ADDRESS 916 Base address where the generic TPM device is mapped 917 to. Contemporary x86 systems usually map it at 918 0xfed40000. 919 920 CONFIG_TPM 921 Define this to enable the TPM support library which provides 922 functional interfaces to some TPM commands. 923 Requires support for a TPM device. 924 925 CONFIG_TPM_AUTH_SESSIONS 926 Define this to enable authorized functions in the TPM library. 927 Requires CONFIG_TPM and CONFIG_SHA1. 928 929- USB Support: 930 At the moment only the UHCI host controller is 931 supported (PIP405, MIP405); define 932 CONFIG_USB_UHCI to enable it. 933 define CONFIG_USB_KEYBOARD to enable the USB Keyboard 934 and define CONFIG_USB_STORAGE to enable the USB 935 storage devices. 936 Note: 937 Supported are USB Keyboards and USB Floppy drives 938 (TEAC FD-05PUB). 939 940 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the 941 txfilltuning field in the EHCI controller on reset. 942 943 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2 944 HW module registers. 945 946- USB Device: 947 Define the below if you wish to use the USB console. 948 Once firmware is rebuilt from a serial console issue the 949 command "setenv stdin usbtty; setenv stdout usbtty" and 950 attach your USB cable. The Unix command "dmesg" should print 951 it has found a new device. The environment variable usbtty 952 can be set to gserial or cdc_acm to enable your device to 953 appear to a USB host as a Linux gserial device or a 954 Common Device Class Abstract Control Model serial device. 955 If you select usbtty = gserial you should be able to enumerate 956 a Linux host by 957 # modprobe usbserial vendor=0xVendorID product=0xProductID 958 else if using cdc_acm, simply setting the environment 959 variable usbtty to be cdc_acm should suffice. The following 960 might be defined in YourBoardName.h 961 962 CONFIG_USB_DEVICE 963 Define this to build a UDC device 964 965 CONFIG_USB_TTY 966 Define this to have a tty type of device available to 967 talk to the UDC device 968 969 CONFIG_USBD_HS 970 Define this to enable the high speed support for usb 971 device and usbtty. If this feature is enabled, a routine 972 int is_usbd_high_speed(void) 973 also needs to be defined by the driver to dynamically poll 974 whether the enumeration has succeded at high speed or full 975 speed. 976 977 If you have a USB-IF assigned VendorID then you may wish to 978 define your own vendor specific values either in BoardName.h 979 or directly in usbd_vendor_info.h. If you don't define 980 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME, 981 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot 982 should pretend to be a Linux device to it's target host. 983 984 CONFIG_USBD_MANUFACTURER 985 Define this string as the name of your company for 986 - CONFIG_USBD_MANUFACTURER "my company" 987 988 CONFIG_USBD_PRODUCT_NAME 989 Define this string as the name of your product 990 - CONFIG_USBD_PRODUCT_NAME "acme usb device" 991 992 CONFIG_USBD_VENDORID 993 Define this as your assigned Vendor ID from the USB 994 Implementors Forum. This *must* be a genuine Vendor ID 995 to avoid polluting the USB namespace. 996 - CONFIG_USBD_VENDORID 0xFFFF 997 998 CONFIG_USBD_PRODUCTID 999 Define this as the unique Product ID 1000 for your device
1001 - CONFIG_USBD_PRODUCTID 0xFFFF 1002 1003- ULPI Layer Support: 1004 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via 1005 the generic ULPI layer. The generic layer accesses the ULPI PHY 1006 via the platform viewport, so you need both the genric layer and 1007 the viewport enabled. Currently only Chipidea/ARC based 1008 viewport is supported. 1009 To enable the ULPI layer support, define CONFIG_USB_ULPI and 1010 CONFIG_USB_ULPI_VIEWPORT in your board configuration file. 1011 If your ULPI phy needs a different reference clock than the 1012 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to 1013 the appropriate value in Hz. 1014 1015- MMC Support: 1016 The MMC controller on the Intel PXA is supported. To 1017 enable this define CONFIG_MMC. The MMC can be 1018 accessed from the boot prompt by mapping the device 1019 to physical memory similar to flash. Command line is 1020 enabled with CONFIG_CMD_MMC. The MMC driver also works with 1021 the FAT fs. This is enabled with CONFIG_CMD_FAT. 1022 1023 CONFIG_SH_MMCIF 1024 Support for Renesas on-chip MMCIF controller 1025 1026 CONFIG_SH_MMCIF_ADDR 1027 Define the base address of MMCIF registers 1028 1029 CONFIG_SH_MMCIF_CLK 1030 Define the clock frequency for MMCIF 1031 1032- USB Device Firmware Update (DFU) class support: 1033 CONFIG_DFU_OVER_USB 1034 This enables the USB portion of the DFU USB class 1035 1036 CONFIG_DFU_NAND 1037 This enables support for exposing NAND devices via DFU. 1038 1039 CONFIG_DFU_RAM 1040 This enables support for exposing RAM via DFU. 1041 Note: DFU spec refer to non-volatile memory usage, but 1042 allow usages beyond the scope of spec - here RAM usage, 1043 one that would help mostly the developer. 1044 1045 CONFIG_SYS_DFU_DATA_BUF_SIZE 1046 Dfu transfer uses a buffer before writing data to the 1047 raw storage device. Make the size (in bytes) of this buffer 1048 configurable. The size of this buffer is also configurable 1049 through the "dfu_bufsiz" environment variable. 1050 1051 CONFIG_SYS_DFU_MAX_FILE_SIZE 1052 When updating files rather than the raw storage device, 1053 we use a static buffer to copy the file into and then write 1054 the buffer once we've been given the whole file. Define 1055 this to the maximum filesize (in bytes) for the buffer. 1056 Default is 4 MiB if undefined. 1057 1058 DFU_DEFAULT_POLL_TIMEOUT 1059 Poll timeout [ms], is the timeout a device can send to the 1060 host. The host must wait for this timeout before sending 1061 a subsequent DFU_GET_STATUS request to the device. 1062 1063 DFU_MANIFEST_POLL_TIMEOUT 1064 Poll timeout [ms], which the device sends to the host when 1065 entering dfuMANIFEST state. Host waits this timeout, before 1066 sending again an USB request to the device. 1067 1068- Journaling Flash filesystem support: 1069 CONFIG_JFFS2_NAND 1070 Define these for a default partition on a NAND device 1071 1072 CONFIG_SYS_JFFS2_FIRST_SECTOR, 1073 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS 1074 Define these for a default partition on a NOR device 1075 1076- Keyboard Support: 1077 See Kconfig help for available keyboard drivers. 1078 1079 CONFIG_KEYBOARD 1080 1081 Define this to enable a custom keyboard support. 1082 This simply calls drv_keyboard_init() which must be 1083 defined in your board-specific files. This option is deprecated 1084 and is only used by novena. For new boards, use driver model 1085 instead. 1086 1087- Video support: 1088 CONFIG_FSL_DIU_FB 1089 Enable the Freescale DIU video driver. Reference boards for 1090 SOCs that have a DIU should define this macro to enable DIU 1091 support, and should also define these other macros: 1092 1093 CONFIG_SYS_DIU_ADDR 1094 CONFIG_VIDEO 1095 CONFIG_CFB_CONSOLE 1096 CONFIG_VIDEO_SW_CURSOR 1097 CONFIG_VGA_AS_SINGLE_DEVICE 1098 CONFIG_VIDEO_LOGO 1099 CONFIG_VIDEO_BMP_LOGO 1100 1101 The DIU driver will look for the 'video-mode' environment 1102 variable, and if defined, enable the DIU as a console during 1103 boot. See the documentation file doc/README.video for a 1104 description of this variable. 1105 1106- LCD Support: CONFIG_LCD 1107 1108 Define this to enable LCD support (for output to LCD 1109 display); also select one of the supported displays 1110 by defining one of these: 1111 1112 CONFIG_ATMEL_LCD: 1113 1114 HITACHI TX09D70VM1CCA, 3.5", 240x320. 1115 1116 CONFIG_NEC_NL6448AC33: 1117 1118 NEC NL6448AC33-18. Active, color, single scan. 1119 1120 CONFIG_NEC_NL6448BC20 1121 1122 NEC NL6448BC20-08. 6.5", 640x480. 1123 Active, color, single scan. 1124 1125 CONFIG_NEC_NL6448BC33_54 1126 1127 NEC NL6448BC33-54. 10.4", 640x480. 1128 Active, color, single scan. 1129 1130 CONFIG_SHARP_16x9 1131 1132 Sharp 320x240. Active, color, single scan. 1133 It isn't 16x9, and I am not sure what it is. 1134 1135 CONFIG_SHARP_LQ64D341 1136 1137 Sharp LQ64D341 display, 640x480. 1138 Active, color, single scan. 1139 1140 CONFIG_HLD1045 1141 1142 HLD1045 display, 640x480. 1143 Active, color, single scan. 1144 1145 CONFIG_OPTREX_BW 1146 1147 Optrex CBL50840-2 NF-FW 99 22 M5 1148 or 1149 Hitachi LMG6912RPFC-00T 1150 or 1151 Hitachi SP14Q002 1152 1153 320x240. Black & white. 1154 1155 CONFIG_LCD_ALIGNMENT 1156 1157 Normally the LCD is page-aligned (typically 4KB). If this is 1158 defined then the LCD will be aligned to this value instead. 1159 For ARM it is sometimes useful to use MMU_SECTION_SIZE 1160 here, since it is cheaper to change data cache settings on 1161 a per-section basis. 1162 1163 1164 CONFIG_LCD_ROTATION 1165 1166 Sometimes, for example if the display is mounted in portrait 1167 mode or even if it's mounted landscape but rotated by 180degree, 1168 we need to rotate our content of the display relative to the 1169 framebuffer, so that user can read the messages which are 1170 printed out. 1171 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be 1172 initialized with a given rotation from "vl_rot" out of 1173 "vidinfo_t" which is provided by the board specific code. 1174 The value for vl_rot is coded as following (matching to 1175 fbcon=rotate:<n> linux-kernel commandline): 1176 0 = no rotation respectively 0 degree 1177 1 = 90 degree rotation 1178 2 = 180 degree rotation 1179 3 = 270 degree rotation 1180 1181 If CONFIG_LCD_ROTATION is not defined, the console will be 1182 initialized with 0degree rotation. 1183 1184 CONFIG_LCD_BMP_RLE8 1185 1186 Support drawing of RLE8-compressed bitmaps on the LCD. 1187 1188- MII/PHY support: 1189 CONFIG_PHY_CLOCK_FREQ (ppc4xx) 1190 1191 The clock frequency of the MII bus 1192 1193 CONFIG_PHY_RESET_DELAY 1194 1195 Some PHY like Intel LXT971A need extra delay after 1196 reset before any MII register access is possible. 1197 For such PHY, set this option to the usec delay 1198 required. (minimum 300usec for LXT971A) 1199 1200 CONFIG_PHY_CMD_DELAY (ppc4xx) 1201 1202 Some PHY like Intel LXT971A need extra delay after 1203 command issued before MII status register can be read 1204 1205- IP address: 1206 CONFIG_IPADDR 1207 1208 Define a default value for the IP address to use for 1209 the default Ethernet interface, in case this is not 1210 determined through e.g. bootp. 1211 (Environment variable "ipaddr") 1212 1213- Server IP address: 1214 CONFIG_SERVERIP 1215 1216 Defines a default value for the IP address of a TFTP 1217 server to contact when using the "tftboot" command. 1218 (Environment variable "serverip") 1219 1220 CONFIG_KEEP_SERVERADDR 1221 1222 Keeps the server's MAC address, in the env 'serveraddr' 1223 for passing to bootargs (like Linux's netconsole option) 1224 1225- Gateway IP address: 1226 CONFIG_GATEWAYIP 1227 1228 Defines a default value for the IP address of the 1229 default router where packets to other networks are 1230 sent to. 1231 (Environment variable "gatewayip") 1232 1233- Subnet mask: 1234 CONFIG_NETMASK 1235 1236 Defines a default value for the subnet mask (or 1237 routing prefix) which is used to determine if an IP 1238 address belongs to the local subnet or needs to be 1239 forwarded through a router. 1240 (Environment variable "netmask") 1241 1242- BOOTP Recovery Mode: 1243 CONFIG_BOOTP_RANDOM_DELAY 1244 1245 If you have many targets in a network that try to 1246 boot using BOOTP, you may want to avoid that all 1247 systems send out BOOTP requests at precisely the same 1248 moment (which would happen for instance at recovery 1249 from a power failure, when all systems will try to 1250 boot, thus flooding the BOOTP server. Defining 1251 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be 1252 inserted before sending out BOOTP requests. The 1253 following delays are inserted then: 1254 1255 1st BOOTP request: delay 0 ... 1 sec 1256 2nd BOOTP request: delay 0 ... 2 sec 1257 3rd BOOTP request: delay 0 ... 4 sec 1258 4th and following 1259 BOOTP requests: delay 0 ... 8 sec 1260 1261 CONFIG_BOOTP_ID_CACHE_SIZE 1262 1263 BOOTP packets are uniquely identified using a 32-bit ID. The 1264 server will copy the ID from client requests to responses and 1265 U-Boot will use this to determine if it is the destination of 1266 an incoming response. Some servers will check that addresses 1267 aren't in use before handing them out (usually using an ARP 1268 ping) and therefore take up to a few hundred milliseconds to 1269 respond. Network congestion may also influence the time it 1270 takes for a response to make it back to the client. If that 1271 time is too long, U-Boot will retransmit requests. In order 1272 to allow earlier responses to still be accepted after these 1273 retransmissions, U-Boot's BOOTP client keeps a small cache of 1274 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this 1275 cache. The default is to keep IDs for up to four outstanding 1276 requests. Increasing this will allow U-Boot to accept offers 1277 from a BOOTP client in networks with unusually high latency. 1278 1279- DHCP Advanced Options: 1280 You can fine tune the DHCP functionality by defining 1281 CONFIG_BOOTP_* symbols: 1282 1283 CONFIG_BOOTP_NISDOMAIN 1284 CONFIG_BOOTP_BOOTFILESIZE 1285 CONFIG_BOOTP_NTPSERVER 1286 CONFIG_BOOTP_TIMEOFFSET 1287 CONFIG_BOOTP_VENDOREX 1288 CONFIG_BOOTP_MAY_FAIL 1289 1290 CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip 1291 environment variable, not the BOOTP server. 1292 1293 CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found 1294 after the configured retry count, the call will fail 1295 instead of starting over. This can be used to fail over 1296 to Link-local IP address configuration if the DHCP server 1297 is not available. 1298 1299 CONFIG_BOOTP_DHCP_REQUEST_DELAY 1300 1301 A 32bit value in microseconds for a delay between 1302 receiving a "DHCP Offer" and sending the "DHCP Request". 1303 This fixes a problem with certain DHCP servers that don't 1304 respond 100% of the time to a "DHCP request". E.g. On an 1305 AT91RM9200 processor running at 180MHz, this delay needed 1306 to be *at least* 15,000 usec before a Windows Server 2003 1307 DHCP server would reply 100% of the time. I recommend at 1308 least 50,000 usec to be safe. The alternative is to hope 1309 that one of the retries will be successful but note that 1310 the DHCP timeout and retry process takes a longer than 1311 this delay. 1312 1313 - Link-local IP address negotiation: 1314 Negotiate with other link-local clients on the local network 1315 for an address that doesn't require explicit configuration. 1316 This is especially useful if a DHCP server cannot be guaranteed 1317 to exist in all environments that the device must operate. 1318 1319 See doc/README.link-local for more information. 1320 1321 - MAC address from environment variables 1322 1323 FDT_SEQ_MACADDR_FROM_ENV 1324 1325 Fix-up device tree with MAC addresses fetched sequentially from 1326 environment variables. This config work on assumption that 1327 non-usable ethernet node of device-tree are either not present 1328 or their status has been marked as "disabled". 1329 1330 - CDP Options: 1331 CONFIG_CDP_DEVICE_ID 1332 1333 The device id used in CDP trigger frames. 1334 1335 CONFIG_CDP_DEVICE_ID_PREFIX 1336 1337 A two character string which is prefixed to the MAC address 1338 of the device. 1339 1340 CONFIG_CDP_PORT_ID 1341 1342 A printf format string which contains the ascii name of 1343 the port. Normally is set to "eth%d" which sets 1344 eth0 for the first Ethernet, eth1 for the second etc. 1345 1346 CONFIG_CDP_CAPABILITIES 1347 1348 A 32bit integer which indicates the device capabilities; 1349 0x00000010 for a normal host which does not forwards. 1350 1351 CONFIG_CDP_VERSION 1352 1353 An ascii string containing the version of the software. 1354 1355 CONFIG_CDP_PLATFORM 1356 1357 An ascii string containing the name of the platform. 1358 1359 CONFIG_CDP_TRIGGER 1360 1361 A 32bit integer sent on the trigger. 1362 1363 CONFIG_CDP_POWER_CONSUMPTION 1364 1365 A 16bit integer containing the power consumption of the 1366 device in .1 of milliwatts. 1367 1368 CONFIG_CDP_APPLIANCE_VLAN_TYPE 1369 1370 A byte containing the id of the VLAN. 1371 1372- Status LED: CONFIG_LED_STATUS 1373 1374 Several configurations allow to display the current 1375 status using a LED. For instance, the LED will blink 1376 fast while running U-Boot code, stop blinking as 1377 soon as a reply to a BOOTP request was received, and 1378 start blinking slow once the Linux kernel is running 1379 (supported by a status LED driver in the Linux 1380 kernel). Defining CONFIG_LED_STATUS enables this 1381 feature in U-Boot. 1382 1383 Additional options: 1384 1385 CONFIG_LED_STATUS_GPIO 1386 The status LED can be connected to a GPIO pin. 1387 In such cases, the gpio_led driver can be used as a 1388 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO 1389 to include the gpio_led driver in the U-Boot binary. 1390 1391 CONFIG_GPIO_LED_INVERTED_TABLE 1392 Some GPIO connected LEDs may have inverted polarity in which 1393 case the GPIO high value corresponds to LED off state and 1394 GPIO low value corresponds to LED on state. 1395 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined 1396 with a list of GPIO LEDs that have inverted polarity. 1397 1398- I2C Support: 1399 CONFIG_SYS_NUM_I2C_BUSES 1400 Hold the number of i2c buses you want to use. 1401 1402 CONFIG_SYS_I2C_DIRECT_BUS 1403 define this, if you don't use i2c muxes on your hardware. 1404 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can 1405 omit this define. 1406 1407 CONFIG_SYS_I2C_MAX_HOPS 1408 define how many muxes are maximal consecutively connected 1409 on one i2c bus. If you not use i2c muxes, omit this 1410 define. 1411 1412 CONFIG_SYS_I2C_BUSES 1413 hold a list of buses you want to use, only used if 1414 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example 1415 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and 1416 CONFIG_SYS_NUM_I2C_BUSES = 9: 1417 1418 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \ 1419 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \ 1420 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \ 1421 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \ 1422 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \ 1423 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \ 1424 {1, {I2C_NULL_HOP}}, \ 1425 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \ 1426 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \ 1427 } 1428 1429 which defines 1430 bus 0 on adapter 0 without a mux 1431 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1 1432 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2 1433 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3 1434 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4 1435 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5 1436 bus 6 on adapter 1 without a mux 1437 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1 1438 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2 1439 1440 If you do not have i2c muxes on your board, omit this define. 1441 1442- Legacy I2C Support: 1443 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT) 1444 then the following macros need to be defined (examples are 1445 from include/configs/lwmon.h): 1446 1447 I2C_INIT 1448 1449 (Optional). Any commands necessary to enable the I2C 1450 controller or configure ports. 1451 1452 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL) 1453 1454 I2C_ACTIVE 1455 1456 The code necessary to make the I2C data line active 1457 (driven). If the data line is open collector, this 1458 define can be null. 1459 1460 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA) 1461 1462 I2C_TRISTATE 1463 1464 The code necessary to make the I2C data line tri-stated 1465 (inactive). If the data line is open collector, this 1466 define can be null. 1467 1468 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA) 1469 1470 I2C_READ 1471 1472 Code that returns true if the I2C data line is high, 1473 false if it is low. 1474 1475 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0) 1476 1477 I2C_SDA(bit) 1478 1479 If <bit> is true, sets the I2C data line high. If it 1480 is false, it clears it (low). 1481 1482 eg: #define I2C_SDA(bit) \ 1483 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \ 1484 else immr->im_cpm.cp_pbdat &= ~PB_SDA 1485 1486 I2C_SCL(bit) 1487 1488 If <bit> is true, sets the I2C clock line high. If it 1489 is false, it clears it (low). 1490 1491 eg: #define I2C_SCL(bit) \ 1492 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \ 1493 else immr->im_cpm.cp_pbdat &= ~PB_SCL 1494 1495 I2C_DELAY 1496 1497 This delay is invoked four times per clock cycle so this 1498 controls the rate of data transfer. The data rate thus 1499 is 1 / (I2C_DELAY * 4). Often defined to be something 1500 like: 1501 1502 #define I2C_DELAY udelay(2) 1503 1504 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA 1505 1506 If your arch supports the generic GPIO framework (asm/gpio.h), 1507 then you may alternatively define the two GPIOs that are to be 1508 used as SCL / SDA. Any of the previous I2C_xxx macros will 1509 have GPIO-based defaults assigned to them as appropriate. 1510 1511 You should define these to the GPIO value as given directly to 1512 the generic GPIO functions. 1513 1514 CONFIG_SYS_I2C_INIT_BOARD 1515 1516 When a board is reset during an i2c bus transfer 1517 chips might think that the current transfer is still 1518 in progress. On some boards it is possible to access 1519 the i2c SCLK line directly, either by using the 1520 processor pin as a GPIO or by having a second pin 1521 connected to the bus. If this option is defined a 1522 custom i2c_init_board() routine in boards/xxx/board.c 1523 is run early in the boot sequence. 1524 1525 CONFIG_I2C_MULTI_BUS 1526 1527 This option allows the use of multiple I2C buses, each of which 1528 must have a controller. At any point in time, only one bus is 1529 active. To switch to a different bus, use the 'i2c dev' command. 1530 Note that bus numbering is zero-based. 1531 1532 CONFIG_SYS_I2C_NOPROBES 1533 1534 This option specifies a list of I2C devices that will be skipped 1535 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS 1536 is set, specify a list of bus-device pairs. Otherwise, specify 1537 a 1D array of device addresses 1538 1539 e.g. 1540 #undef CONFIG_I2C_MULTI_BUS 1541 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68} 1542 1543 will skip addresses 0x50 and 0x68 on a board with one I2C bus 1544 1545 #define CONFIG_I2C_MULTI_BUS 1546 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}} 1547 1548 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1 1549 1550 CONFIG_SYS_SPD_BUS_NUM 1551 1552 If defined, then this indicates the I2C bus number for DDR SPD. 1553 If not defined, then U-Boot assumes that SPD is on I2C bus 0. 1554 1555 CONFIG_SYS_RTC_BUS_NUM 1556 1557 If defined, then this indicates the I2C bus number for the RTC. 1558 If not defined, then U-Boot assumes that RTC is on I2C bus 0. 1559 1560 CONFIG_SOFT_I2C_READ_REPEATED_START 1561 1562 defining this will force the i2c_read() function in 1563 the soft_i2c driver to perform an I2C repeated start 1564 between writing the address pointer and reading the 1565 data. If this define is omitted the default behaviour 1566 of doing a stop-start sequence will be used. Most I2C 1567 devices can use either method, but some require one or 1568 the other. 1569 1570- SPI Support: CONFIG_SPI 1571 1572 Enables SPI driver (so far only tested with 1573 SPI EEPROM, also an instance works with Crystal A/D and 1574 D/As on the SACSng board) 1575 1576 CONFIG_SOFT_SPI 1577 1578 Enables a software (bit-bang) SPI driver rather than 1579 using hardware support. This is a general purpose 1580 driver that only requires three general I/O port pins 1581 (two outputs, one input) to function. If this is 1582 defined, the board configuration must define several 1583 SPI configuration items (port pins to use, etc). For 1584 an example, see include/configs/sacsng.h. 1585 1586 CONFIG_SYS_SPI_MXC_WAIT 1587 Timeout for waiting until spi transfer completed. 1588 default: (CONFIG_SYS_HZ/100) /* 10 ms */ 1589 1590- FPGA Support: CONFIG_FPGA 1591 1592 Enables FPGA subsystem. 1593 1594 CONFIG_FPGA_<vendor> 1595 1596 Enables support for specific chip vendors. 1597 (ALTERA, XILINX) 1598 1599 CONFIG_FPGA_<family> 1600 1601 Enables support for FPGA family. 1602 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX) 1603 1604 CONFIG_FPGA_COUNT 1605 1606 Specify the number of FPGA devices to support. 1607 1608 CONFIG_SYS_FPGA_PROG_FEEDBACK 1609 1610 Enable printing of hash marks during FPGA configuration. 1611 1612 CONFIG_SYS_FPGA_CHECK_BUSY 1613 1614 Enable checks on FPGA configuration interface busy 1615 status by the configuration function. This option 1616 will require a board or device specific function to 1617 be written. 1618 1619 CONFIG_FPGA_DELAY 1620 1621 If defined, a function that provides delays in the FPGA 1622 configuration driver. 1623 1624 CONFIG_SYS_FPGA_CHECK_CTRLC 1625 Allow Control-C to interrupt FPGA configuration 1626 1627 CONFIG_SYS_FPGA_CHECK_ERROR 1628 1629 Check for configuration errors during FPGA bitfile 1630 loading. For example, abort during Virtex II 1631 configuration if the INIT_B line goes low (which 1632 indicated a CRC error). 1633 1634 CONFIG_SYS_FPGA_WAIT_INIT 1635 1636 Maximum time to wait for the INIT_B line to de-assert 1637 after PROB_B has been de-asserted during a Virtex II 1638 FPGA configuration sequence. The default time is 500 1639 ms. 1640 1641 CONFIG_SYS_FPGA_WAIT_BUSY 1642 1643 Maximum time to wait for BUSY to de-assert during 1644 Virtex II FPGA configuration. The default is 5 ms. 1645 1646 CONFIG_SYS_FPGA_WAIT_CONFIG 1647 1648 Time to wait after FPGA configuration. The default is 1649 200 ms. 1650 1651- Configuration Management: 1652 1653 CONFIG_IDENT_STRING 1654 1655 If defined, this string will be added to the U-Boot 1656 version information (U_BOOT_VERSION) 1657 1658- Vendor Parameter Protection: 1659 1660 U-Boot considers the values of the environment 1661 variables "serial#" (Board Serial Number) and 1662 "ethaddr" (Ethernet Address) to be parameters that 1663 are set once by the board vendor / manufacturer, and 1664 protects these variables from casual modification by 1665 the user. Once set, these variables are read-only, 1666 and write or delete attempts are rejected. You can 1667 change this behaviour: 1668 1669 If CONFIG_ENV_OVERWRITE is #defined in your config 1670 file, the write protection for vendor parameters is 1671 completely disabled. Anybody can change or delete 1672 these parameters. 1673 1674 Alternatively, if you define _both_ an ethaddr in the 1675 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default 1676 Ethernet address is installed in the environment, 1677 which can be changed exactly ONCE by the user. [The 1678 serial# is unaffected by this, i. e. it remains 1679 read-only.] 1680 1681 The same can be accomplished in a more flexible way 1682 for any variable by configuring the type of access 1683 to allow for those variables in the ".flags" variable 1684 or define CONFIG_ENV_FLAGS_LIST_STATIC. 1685 1686- Protected RAM: 1687 CONFIG_PRAM 1688 1689 Define this variable to enable the reservation of 1690 "protected RAM", i. e. RAM which is not overwritten 1691 by U-Boot. Define CONFIG_PRAM to hold the number of 1692 kB you want to reserve for pRAM. You can overwrite 1693 this default value by defining an environment 1694 variable "pram" to the number of kB you want to 1695 reserve. Note that the board info structure will 1696 still show the full amount of RAM. If pRAM is 1697 reserved, a new environment variable "mem" will 1698 automatically be defined to hold the amount of 1699 remaining RAM in a form that can be passed as boot 1700 argument to Linux, for instance like that: 1701 1702 setenv bootargs ... mem=\${mem} 1703 saveenv 1704 1705 This way you can tell Linux not to use this memory, 1706 either, which results in a memory region that will 1707 not be affected by reboots. 1708 1709 *WARNING* If your board configuration uses automatic 1710 detection of the RAM size, you must make sure that 1711 this memory test is non-destructive. So far, the 1712 following board configurations are known to be 1713 "pRAM-clean": 1714 1715 IVMS8, IVML24, SPD8xx, 1716 HERMES, IP860, RPXlite, LWMON, 1717 FLAGADM 1718 1719- Access to physical memory region (> 4GB) 1720 Some basic support is provided for operations on memory not 1721 normally accessible to U-Boot - e.g. some architectures 1722 support access to more than 4GB of memory on 32-bit 1723 machines using physical address extension or similar. 1724 Define CONFIG_PHYSMEM to access this basic support, which 1725 currently only supports clearing the memory. 1726 1727- Error Recovery: 1728 CONFIG_NET_RETRY_COUNT 1729 1730 This variable defines the number of retries for 1731 network operations like ARP, RARP, TFTP, or BOOTP 1732 before giving up the operation. If not defined, a 1733 default value of 5 is used. 1734 1735 CONFIG_ARP_TIMEOUT 1736 1737 Timeout waiting for an ARP reply in milliseconds. 1738 1739 CONFIG_NFS_TIMEOUT 1740 1741 Timeout in milliseconds used in NFS protocol. 1742 If you encounter "ERROR: Cannot umount" in nfs command, 1743 try longer timeout such as 1744 #define CONFIG_NFS_TIMEOUT 10000UL 1745 1746 Note: 1747 1748 In the current implementation, the local variables 1749 space and global environment variables space are 1750 separated. Local variables are those you define by 1751 simply typing `name=value'. To access a local 1752 variable later on, you have write `$name' or 1753 `${name}'; to execute the contents of a variable 1754 directly type `$name' at the command prompt. 1755 1756 Global environment variables are those you use 1757 setenv/printenv to work with. To run a command stored 1758 in such a variable, you need to use the run command, 1759 and you must not use the '$' sign to access them. 1760 1761 To store commands and special characters in a 1762 variable, please use double quotation marks 1763 surrounding the whole text of the variable, instead 1764 of the backslashes before semicolons and special 1765 symbols. 1766 1767- Command Line Editing and History: 1768 CONFIG_CMDLINE_PS_SUPPORT 1769 1770 Enable support for changing the command prompt string 1771 at run-time. Only static string is supported so far. 1772 The string is obtained from environment variables PS1 1773 and PS2. 1774 1775- Default Environment: 1776 CONFIG_EXTRA_ENV_SETTINGS 1777 1778 Define this to contain any number of null terminated 1779 strings (variable = value pairs) that will be part of 1780 the default environment compiled into the boot image. 1781 1782 For example, place something like this in your 1783 board's config file: 1784 1785 #define CONFIG_EXTRA_ENV_SETTINGS \ 1786 "myvar1=value1\0" \ 1787 "myvar2=value2\0" 1788 1789 Warning: This method is based on knowledge about the 1790 internal format how the environment is stored by the 1791 U-Boot code. This is NOT an official, exported 1792 interface! Although it is unlikely that this format 1793 will change soon, there is no guarantee either. 1794 You better know what you are doing here. 1795 1796 Note: overly (ab)use of the default environment is 1797 discouraged. Make sure to check other ways to preset 1798 the environment like the "source" command or the 1799 boot command first. 1800 1801 CONFIG_DELAY_ENVIRONMENT 1802 1803 Normally the environment is loaded when the board is 1804 initialised so that it is available to U-Boot. This inhibits 1805 that so that the environment is not available until 1806 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL 1807 this is instead controlled by the value of 1808 /config/load-environment. 1809 1810- TFTP Fixed UDP Port: 1811 CONFIG_TFTP_PORT 1812 1813 If this is defined, the environment variable tftpsrcp 1814 is used to supply the TFTP UDP source port value. 1815 If tftpsrcp isn't defined, the normal pseudo-random port 1816 number generator is used. 1817 1818 Also, the environment variable tftpdstp is used to supply 1819 the TFTP UDP destination port value. If tftpdstp isn't 1820 defined, the normal port 69 is used. 1821 1822 The purpose for tftpsrcp is to allow a TFTP server to 1823 blindly start the TFTP transfer using the pre-configured 1824 target IP address and UDP port. This has the effect of 1825 "punching through" the (Windows XP) firewall, allowing 1826 the remainder of the TFTP transfer to proceed normally. 1827 A better solution is to properly configure the firewall, 1828 but sometimes that is not allowed. 1829 1830 CONFIG_STANDALONE_LOAD_ADDR 1831 1832 This option defines a board specific value for the 1833 address where standalone program gets loaded, thus 1834 overwriting the architecture dependent default 1835 settings. 1836 1837- Frame Buffer Address: 1838 CONFIG_FB_ADDR 1839 1840 Define CONFIG_FB_ADDR if you want to use specific 1841 address for frame buffer. This is typically the case 1842 when using a graphics controller has separate video 1843 memory. U-Boot will then place the frame buffer at 1844 the given address instead of dynamically reserving it 1845 in system RAM by calling lcd_setmem(), which grabs 1846 the memory for the frame buffer depending on the 1847 configured panel size. 1848 1849 Please see board_init_f function. 1850 1851- Automatic software updates via TFTP server 1852 CONFIG_UPDATE_TFTP 1853 CONFIG_UPDATE_TFTP_CNT_MAX 1854 CONFIG_UPDATE_TFTP_MSEC_MAX 1855 1856 These options enable and control the auto-update feature; 1857 for a more detailed description refer to doc/README.update. 1858 1859- MTD Support (mtdparts command, UBI support) 1860 CONFIG_MTD_UBI_WL_THRESHOLD 1861 This parameter defines the maximum difference between the highest 1862 erase counter value and the lowest erase counter value of eraseblocks 1863 of UBI devices. When this threshold is exceeded, UBI starts performing 1864 wear leveling by means of moving data from eraseblock with low erase 1865 counter to eraseblocks with high erase counter. 1866 1867 The default value should be OK for SLC NAND flashes, NOR flashes and 1868 other flashes which have eraseblock life-cycle 100000 or more. 1869 However, in case of MLC NAND flashes which typically have eraseblock 1870 life-cycle less than 10000, the threshold should be lessened (e.g., 1871 to 128 or 256, although it does not have to be power of 2). 1872 1873 default: 4096 1874 1875 CONFIG_MTD_UBI_BEB_LIMIT 1876 This option specifies the maximum bad physical eraseblocks UBI 1877 expects on the MTD device (per 1024 eraseblocks). If the 1878 underlying flash does not admit of bad eraseblocks (e.g. NOR 1879 flash), this value is ignored. 1880 1881 NAND datasheets often specify the minimum and maximum NVM 1882 (Number of Valid Blocks) for the flashes' endurance lifetime. 1883 The maximum expected bad eraseblocks per 1024 eraseblocks 1884 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)", 1885 which gives 20 for most NANDs (MaxNVB is basically the total 1886 count of eraseblocks on the chip). 1887 1888 To put it differently, if this value is 20, UBI will try to 1889 reserve about 1.9% of physical eraseblocks for bad blocks 1890 handling. And that will be 1.9% of eraseblocks on the entire 1891 NAND chip, not just the MTD partition UBI attaches. This means 1892 that if you have, say, a NAND flash chip admits maximum 40 bad 1893 eraseblocks, and it is split on two MTD partitions of the same 1894 size, UBI will reserve 40 eraseblocks when attaching a 1895 partition. 1896 1897 default: 20 1898 1899 CONFIG_MTD_UBI_FASTMAP 1900 Fastmap is a mechanism which allows attaching an UBI device 1901 in nearly constant time. Instead of scanning the whole MTD device it 1902 only has to locate a checkpoint (called fastmap) on the device. 1903 The on-flash fastmap contains all information needed to attach 1904 the device. Using fastmap makes only sense on large devices where 1905 attaching by scanning takes long. UBI will not automatically install 1906 a fastmap on old images, but you can set the UBI parameter 1907 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note 1908 that fastmap-enabled images are still usable with UBI implementations 1909 without fastmap support. On typical flash devices the whole fastmap 1910 fits into one PEB. UBI will reserve PEBs to hold two fastmaps. 1911 1912 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT 1913 Set this parameter to enable fastmap automatically on images 1914 without a fastmap. 1915 default: 0 1916 1917 CONFIG_MTD_UBI_FM_DEBUG 1918 Enable UBI fastmap debug 1919 default: 0 1920 1921- SPL framework 1922 CONFIG_SPL 1923 Enable building of SPL globally. 1924 1925 CONFIG_SPL_MAX_FOOTPRINT 1926 Maximum size in memory allocated to the SPL, BSS included. 1927 When defined, the linker checks that the actual memory 1928 used by SPL from _start to __bss_end does not exceed it. 1929 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE 1930 must not be both defined at the same time. 1931 1932 CONFIG_SPL_MAX_SIZE 1933 Maximum size of the SPL image (text, data, rodata, and 1934 linker lists sections), BSS excluded. 1935 When defined, the linker checks that the actual size does 1936 not exceed it. 1937 1938 CONFIG_SPL_RELOC_TEXT_BASE 1939 Address to relocate to. If unspecified, this is equal to 1940 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done). 1941 1942 CONFIG_SPL_BSS_START_ADDR 1943 Link address for the BSS within the SPL binary. 1944 1945 CONFIG_SPL_BSS_MAX_SIZE 1946 Maximum size in memory allocated to the SPL BSS. 1947 When defined, the linker checks that the actual memory used 1948 by SPL from __bss_start to __bss_end does not exceed it. 1949 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE 1950 must not be both defined at the same time. 1951 1952 CONFIG_SPL_STACK 1953 Adress of the start of the stack SPL will use 1954 1955 CONFIG_SPL_PANIC_ON_RAW_IMAGE 1956 When defined, SPL will panic() if the image it has 1957 loaded does not have a signature. 1958 Defining this is useful when code which loads images 1959 in SPL cannot guarantee that absolutely all read errors 1960 will be caught. 1961 An example is the LPC32XX MLC NAND driver, which will 1962 consider that a completely unreadable NAND block is bad, 1963 and thus should be skipped silently. 1964 1965 CONFIG_SPL_RELOC_STACK 1966 Adress of the start of the stack SPL will use after 1967 relocation. If unspecified, this is equal to 1968 CONFIG_SPL_STACK. 1969 1970 CONFIG_SYS_SPL_MALLOC_START 1971 Starting address of the malloc pool used in SPL. 1972 When this option is set the full malloc is used in SPL and 1973 it is set up by spl_init() and before that, the simple malloc() 1974 can be used if CONFIG_SYS_MALLOC_F is defined. 1975 1976 CONFIG_SYS_SPL_MALLOC_SIZE 1977 The size of the malloc pool used in SPL. 1978 1979 CONFIG_SPL_DISPLAY_PRINT 1980 For ARM, enable an optional function to print more information 1981 about the running system. 1982 1983 CONFIG_SPL_INIT_MINIMAL 1984 Arch init code should be built for a very small image 1985 1986 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION 1987 Partition on the MMC to load U-Boot from when the MMC is being 1988 used in raw mode 1989 1990 CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR 1991 Sector to load kernel uImage from when MMC is being 1992 used in raw mode (for Falcon mode) 1993 1994 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR, 1995 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS 1996 Sector and number of sectors to load kernel argument 1997 parameters from when MMC is being used in raw mode 1998 (for falcon mode) 1999 2000 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
2001 Filename to read to load U-Boot when reading from filesystem 2002 2003 CONFIG_SPL_FS_LOAD_KERNEL_NAME 2004 Filename to read to load kernel uImage when reading 2005 from filesystem (for Falcon mode) 2006 2007 CONFIG_SPL_FS_LOAD_ARGS_NAME 2008 Filename to read to load kernel argument parameters 2009 when reading from filesystem (for Falcon mode) 2010 2011 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND 2012 Set this for NAND SPL on PPC mpc83xx targets, so that 2013 start.S waits for the rest of the SPL to load before 2014 continuing (the hardware starts execution after just 2015 loading the first page rather than the full 4K). 2016 2017 CONFIG_SPL_SKIP_RELOCATE 2018 Avoid SPL relocation 2019 2020 CONFIG_SPL_NAND_IDENT 2021 SPL uses the chip ID list to identify the NAND flash. 2022 Requires CONFIG_SPL_NAND_BASE. 2023 2024 CONFIG_SPL_UBI 2025 Support for a lightweight UBI (fastmap) scanner and 2026 loader 2027 2028 CONFIG_SPL_NAND_RAW_ONLY 2029 Support to boot only raw u-boot.bin images. Use this only 2030 if you need to save space. 2031 2032 CONFIG_SPL_COMMON_INIT_DDR 2033 Set for common ddr init with serial presence detect in 2034 SPL binary. 2035 2036 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT, 2037 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE, 2038 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS, 2039 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE, 2040 CONFIG_SYS_NAND_ECCBYTES 2041 Defines the size and behavior of the NAND that SPL uses 2042 to read U-Boot 2043 2044 CONFIG_SYS_NAND_U_BOOT_DST 2045 Location in memory to load U-Boot to 2046 2047 CONFIG_SYS_NAND_U_BOOT_SIZE 2048 Size of image to load 2049 2050 CONFIG_SYS_NAND_U_BOOT_START 2051 Entry point in loaded image to jump to 2052 2053 CONFIG_SYS_NAND_HW_ECC_OOBFIRST 2054 Define this if you need to first read the OOB and then the 2055 data. This is used, for example, on davinci platforms. 2056 2057 CONFIG_SPL_RAM_DEVICE 2058 Support for running image already present in ram, in SPL binary 2059 2060 CONFIG_SPL_PAD_TO 2061 Image offset to which the SPL should be padded before appending 2062 the SPL payload. By default, this is defined as 2063 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined. 2064 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL 2065 payload without any padding, or >= CONFIG_SPL_MAX_SIZE. 2066 2067 CONFIG_SPL_TARGET 2068 Final target image containing SPL and payload. Some SPLs 2069 use an arch-specific makefile fragment instead, for 2070 example if more than one image needs to be produced. 2071 2072 CONFIG_SPL_FIT_PRINT 2073 Printing information about a FIT image adds quite a bit of 2074 code to SPL. So this is normally disabled in SPL. Use this 2075 option to re-enable it. This will affect the output of the 2076 bootm command when booting a FIT image. 2077 2078- TPL framework 2079 CONFIG_TPL 2080 Enable building of TPL globally. 2081 2082 CONFIG_TPL_PAD_TO 2083 Image offset to which the TPL should be padded before appending 2084 the TPL payload. By default, this is defined as 2085 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined. 2086 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL 2087 payload without any padding, or >= CONFIG_SPL_MAX_SIZE. 2088 2089- Interrupt support (PPC): 2090 2091 There are common interrupt_init() and timer_interrupt() 2092 for all PPC archs. interrupt_init() calls interrupt_init_cpu() 2093 for CPU specific initialization. interrupt_init_cpu() 2094 should set decrementer_count to appropriate value. If 2095 CPU resets decrementer automatically after interrupt 2096 (ppc4xx) it should set decrementer_count to zero. 2097 timer_interrupt() calls timer_interrupt_cpu() for CPU 2098 specific handling. If board has watchdog / status_led 2099 / other_activity_monitor it works automatically from 2100 general timer_interrupt(). 2101 2102 2103Board initialization settings: 2104------------------------------ 2105 2106During Initialization u-boot calls a number of board specific functions 2107to allow the preparation of board specific prerequisites, e.g. pin setup 2108before drivers are initialized. To enable these callbacks the 2109following configuration macros have to be defined. Currently this is 2110architecture specific, so please check arch/your_architecture/lib/board.c 2111typically in board_init_f() and board_init_r(). 2112 2113- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f() 2114- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r() 2115- CONFIG_BOARD_LATE_INIT: Call board_late_init() 2116- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init() 2117 2118Configuration Settings: 2119----------------------- 2120 2121- MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit. 2122 Optionally it can be defined to support 64-bit memory commands. 2123 2124- CONFIG_SYS_LONGHELP: Defined when you want long help messages included; 2125 undefine this when you're short of memory. 2126 2127- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default 2128 width of the commands listed in the 'help' command output. 2129 2130- CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to 2131 prompt for user input. 2132 2133- CONFIG_SYS_CBSIZE: Buffer size for input from the Console 2134 2135- CONFIG_SYS_PBSIZE: Buffer size for Console output 2136 2137- CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands 2138 2139- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to 2140 the application (usually a Linux kernel) when it is 2141 booted 2142 2143- CONFIG_SYS_BAUDRATE_TABLE: 2144 List of legal baudrate settings for this board. 2145 2146- CONFIG_SYS_MEM_RESERVE_SECURE 2147 Only implemented for ARMv8 for now. 2148 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory 2149 is substracted from total RAM and won't be reported to OS. 2150 This memory can be used as secure memory. A variable 2151 gd->arch.secure_ram is used to track the location. In systems 2152 the RAM base is not zero, or RAM is divided into banks, 2153 this variable needs to be recalcuated to get the address. 2154 2155- CONFIG_SYS_MEM_TOP_HIDE: 2156 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header, 2157 this specified memory area will get subtracted from the top 2158 (end) of RAM and won't get "touched" at all by U-Boot. By 2159 fixing up gd->ram_size the Linux kernel should gets passed 2160 the now "corrected" memory size and won't touch it either. 2161 This should work for arch/ppc and arch/powerpc. Only Linux 2162 board ports in arch/powerpc with bootwrapper support that 2163 recalculate the memory size from the SDRAM controller setup 2164 will have to get fixed in Linux additionally. 2165 2166 This option can be used as a workaround for the 440EPx/GRx 2167 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't 2168 be touched. 2169 2170 WARNING: Please make sure that this value is a multiple of 2171 the Linux page size (normally 4k). If this is not the case, 2172 then the end address of the Linux memory will be located at a 2173 non page size aligned address and this could cause major 2174 problems. 2175 2176- CONFIG_SYS_LOADS_BAUD_CHANGE: 2177 Enable temporary baudrate change while serial download 2178 2179- CONFIG_SYS_SDRAM_BASE: 2180 Physical start address of SDRAM. _Must_ be 0 here. 2181 2182- CONFIG_SYS_FLASH_BASE: 2183 Physical start address of Flash memory. 2184 2185- CONFIG_SYS_MONITOR_BASE: 2186 Physical start address of boot monitor code (set by 2187 make config files to be same as the text base address 2188 (CONFIG_SYS_TEXT_BASE) used when linking) - same as 2189 CONFIG_SYS_FLASH_BASE when booting from flash. 2190 2191- CONFIG_SYS_MONITOR_LEN: 2192 Size of memory reserved for monitor code, used to 2193 determine _at_compile_time_ (!) if the environment is 2194 embedded within the U-Boot image, or in a separate 2195 flash sector. 2196 2197- CONFIG_SYS_MALLOC_LEN: 2198 Size of DRAM reserved for malloc() use. 2199 2200- CONFIG_SYS_MALLOC_F_LEN 2201 Size of the malloc() pool for use before relocation. If 2202 this is defined, then a very simple malloc() implementation 2203 will become available before relocation. The address is just 2204 below the global data, and the stack is moved down to make 2205 space. 2206 2207 This feature allocates regions with increasing addresses 2208 within the region. calloc() is supported, but realloc() 2209 is not available. free() is supported but does nothing. 2210 The memory will be freed (or in fact just forgotten) when 2211 U-Boot relocates itself. 2212 2213- CONFIG_SYS_MALLOC_SIMPLE 2214 Provides a simple and small malloc() and calloc() for those 2215 boards which do not use the full malloc in SPL (which is 2216 enabled with CONFIG_SYS_SPL_MALLOC_START). 2217 2218- CONFIG_SYS_NONCACHED_MEMORY: 2219 Size of non-cached memory area. This area of memory will be 2220 typically located right below the malloc() area and mapped 2221 uncached in the MMU. This is useful for drivers that would 2222 otherwise require a lot of explicit cache maintenance. For 2223 some drivers it's also impossible to properly maintain the 2224 cache. For example if the regions that need to be flushed 2225 are not a multiple of the cache-line size, *and* padding 2226 cannot be allocated between the regions to align them (i.e. 2227 if the HW requires a contiguous array of regions, and the 2228 size of each region is not cache-aligned), then a flush of 2229 one region may result in overwriting data that hardware has 2230 written to another region in the same cache-line. This can 2231 happen for example in network drivers where descriptors for 2232 buffers are typically smaller than the CPU cache-line (e.g. 2233 16 bytes vs. 32 or 64 bytes). 2234 2235 Non-cached memory is only supported on 32-bit ARM at present. 2236 2237- CONFIG_SYS_BOOTM_LEN: 2238 Normally compressed uImages are limited to an 2239 uncompressed size of 8 MBytes. If this is not enough, 2240 you can define CONFIG_SYS_BOOTM_LEN in your board config file 2241 to adjust this setting to your needs. 2242 2243- CONFIG_SYS_BOOTMAPSZ: 2244 Maximum size of memory mapped by the startup code of 2245 the Linux kernel; all data that must be processed by 2246 the Linux kernel (bd_info, boot arguments, FDT blob if 2247 used) must be put below this limit, unless "bootm_low" 2248 environment variable is defined and non-zero. In such case 2249 all data for the Linux kernel must be between "bootm_low" 2250 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment 2251 variable "bootm_mapsize" will override the value of 2252 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined, 2253 then the value in "bootm_size" will be used instead. 2254 2255- CONFIG_SYS_BOOT_RAMDISK_HIGH: 2256 Enable initrd_high functionality. If defined then the 2257 initrd_high feature is enabled and the bootm ramdisk subcommand 2258 is enabled. 2259 2260- CONFIG_SYS_BOOT_GET_CMDLINE: 2261 Enables allocating and saving kernel cmdline in space between 2262 "bootm_low" and "bootm_low" + BOOTMAPSZ. 2263 2264- CONFIG_SYS_BOOT_GET_KBD: 2265 Enables allocating and saving a kernel copy of the bd_info in 2266 space between "bootm_low" and "bootm_low" + BOOTMAPSZ. 2267 2268- CONFIG_SYS_MAX_FLASH_BANKS: 2269 Max number of Flash memory banks 2270 2271- CONFIG_SYS_MAX_FLASH_SECT: 2272 Max number of sectors on a Flash chip 2273 2274- CONFIG_SYS_FLASH_ERASE_TOUT: 2275 Timeout for Flash erase operations (in ms) 2276 2277- CONFIG_SYS_FLASH_WRITE_TOUT: 2278 Timeout for Flash write operations (in ms) 2279 2280- CONFIG_SYS_FLASH_LOCK_TOUT 2281 Timeout for Flash set sector lock bit operation (in ms) 2282 2283- CONFIG_SYS_FLASH_UNLOCK_TOUT 2284 Timeout for Flash clear lock bits operation (in ms) 2285 2286- CONFIG_SYS_FLASH_PROTECTION 2287 If defined, hardware flash sectors protection is used 2288 instead of U-Boot software protection. 2289 2290- CONFIG_SYS_DIRECT_FLASH_TFTP: 2291 2292 Enable TFTP transfers directly to flash memory; 2293 without this option such a download has to be 2294 performed in two steps: (1) download to RAM, and (2) 2295 copy from RAM to flash. 2296 2297 The two-step approach is usually more reliable, since 2298 you can check if the download worked before you erase 2299 the flash, but in some situations (when system RAM is 2300 too limited to allow for a temporary copy of the 2301 downloaded image) this option may be very useful. 2302 2303- CONFIG_SYS_FLASH_CFI: 2304 Define if the flash driver uses extra elements in the 2305 common flash structure for storing flash geometry. 2306 2307- CONFIG_FLASH_CFI_DRIVER 2308 This option also enables the building of the cfi_flash driver 2309 in the drivers directory 2310 2311- CONFIG_FLASH_CFI_MTD 2312 This option enables the building of the cfi_mtd driver 2313 in the drivers directory. The driver exports CFI flash 2314 to the MTD layer. 2315 2316- CONFIG_SYS_FLASH_USE_BUFFER_WRITE 2317 Use buffered writes to flash. 2318 2319- CONFIG_FLASH_SPANSION_S29WS_N 2320 s29ws-n MirrorBit flash has non-standard addresses for buffered 2321 write commands. 2322 2323- CONFIG_SYS_FLASH_QUIET_TEST 2324 If this option is defined, the common CFI flash doesn't 2325 print it's warning upon not recognized FLASH banks. This 2326 is useful, if some of the configured banks are only 2327 optionally available. 2328 2329- CONFIG_FLASH_SHOW_PROGRESS 2330 If defined (must be an integer), print out countdown 2331 digits and dots. Recommended value: 45 (9..1) for 80 2332 column displays, 15 (3..1) for 40 column displays. 2333 2334- CONFIG_FLASH_VERIFY 2335 If defined, the content of the flash (destination) is compared 2336 against the source after the write operation. An error message 2337 will be printed when the contents are not identical. 2338 Please note that this option is useless in nearly all cases, 2339 since such flash programming errors usually are detected earlier 2340 while unprotecting/erasing/programming. Please only enable 2341 this option if you really know what you are doing. 2342 2343- CONFIG_SYS_RX_ETH_BUFFER: 2344 Defines the number of Ethernet receive buffers. On some 2345 Ethernet controllers it is recommended to set this value 2346 to 8 or even higher (EEPRO100 or 405 EMAC), since all 2347 buffers can be full shortly after enabling the interface 2348 on high Ethernet traffic. 2349 Defaults to 4 if not defined. 2350 2351- CONFIG_ENV_MAX_ENTRIES 2352 2353 Maximum number of entries in the hash table that is used 2354 internally to store the environment settings. The default 2355 setting is supposed to be generous and should work in most 2356 cases. This setting can be used to tune behaviour; see 2357 lib/hashtable.c for details. 2358 2359- CONFIG_ENV_FLAGS_LIST_DEFAULT 2360- CONFIG_ENV_FLAGS_LIST_STATIC 2361 Enable validation of the values given to environment variables when 2362 calling env set. Variables can be restricted to only decimal, 2363 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined, 2364 the variables can also be restricted to IP address or MAC address. 2365 2366 The format of the list is: 2367 type_attribute = [s|d|x|b|i|m] 2368 access_attribute = [a|r|o|c] 2369 attributes = type_attribute[access_attribute] 2370 entry = variable_name[:attributes] 2371 list = entry[,list] 2372 2373 The type attributes are: 2374 s - String (default) 2375 d - Decimal 2376 x - Hexadecimal 2377 b - Boolean ([1yYtT|0nNfF]) 2378 i - IP address 2379 m - MAC address 2380 2381 The access attributes are: 2382 a - Any (default) 2383 r - Read-only 2384 o - Write-once 2385 c - Change-default 2386 2387 - CONFIG_ENV_FLAGS_LIST_DEFAULT 2388 Define this to a list (string) to define the ".flags" 2389 environment variable in the default or embedded environment. 2390 2391 - CONFIG_ENV_FLAGS_LIST_STATIC 2392 Define this to a list (string) to define validation that 2393 should be done if an entry is not found in the ".flags" 2394 environment variable. To override a setting in the static 2395 list, simply add an entry for the same variable name to the 2396 ".flags" variable. 2397 2398 If CONFIG_REGEX is defined, the variable_name above is evaluated as a 2399 regular expression. This allows multiple variables to define the same 2400 flags without explicitly listing them for each variable. 2401 2402The following definitions that deal with the placement and management 2403of environment data (variable area); in general, we support the 2404following configurations: 2405 2406- CONFIG_BUILD_ENVCRC: 2407 2408 Builds up envcrc with the target environment so that external utils 2409 may easily extract it and embed it in final U-Boot images. 2410 2411BE CAREFUL! The first access to the environment happens quite early 2412in U-Boot initialization (when we try to get the setting of for the 2413console baudrate). You *MUST* have mapped your NVRAM area then, or 2414U-Boot will hang. 2415 2416Please note that even with NVRAM we still use a copy of the 2417environment in RAM: we could work on NVRAM directly, but we want to 2418keep settings there always unmodified except somebody uses "saveenv" 2419to save the current settings. 2420 2421BE CAREFUL! For some special cases, the local device can not use 2422"saveenv" command. For example, the local device will get the 2423environment stored in a remote NOR flash by SRIO or PCIE link, 2424but it can not erase, write this NOR flash by SRIO or PCIE interface. 2425 2426- CONFIG_NAND_ENV_DST 2427 2428 Defines address in RAM to which the nand_spl code should copy the 2429 environment. If redundant environment is used, it will be copied to 2430 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE. 2431 2432Please note that the environment is read-only until the monitor 2433has been relocated to RAM and a RAM copy of the environment has been 2434created; also, when using EEPROM you will have to use env_get_f() 2435until then to read environment variables. 2436 2437The environment is protected by a CRC32 checksum. Before the monitor 2438is relocated into RAM, as a result of a bad CRC you will be working 2439with the compiled-in default environment - *silently*!!! [This is 2440necessary, because the first environment variable we need is the 2441"baudrate" setting for the console - if we have a bad CRC, we don't 2442have any device yet where we could complain.] 2443 2444Note: once the monitor has been relocated, then it will complain if 2445the default environment is used; a new CRC is computed as soon as you 2446use the "saveenv" command to store a valid environment. 2447 2448- CONFIG_SYS_FAULT_ECHO_LINK_DOWN: 2449 Echo the inverted Ethernet link state to the fault LED. 2450 2451 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR 2452 also needs to be defined. 2453 2454- CONFIG_SYS_FAULT_MII_ADDR: 2455 MII address of the PHY to check for the Ethernet link state. 2456 2457- CONFIG_NS16550_MIN_FUNCTIONS: 2458 Define this if you desire to only have use of the NS16550_init 2459 and NS16550_putc functions for the serial driver located at 2460 drivers/serial/ns16550.c. This option is useful for saving 2461 space for already greatly restricted images, including but not 2462 limited to NAND_SPL configurations. 2463 2464- CONFIG_DISPLAY_BOARDINFO 2465 Display information about the board that U-Boot is running on 2466 when U-Boot starts up. The board function checkboard() is called 2467 to do this. 2468 2469- CONFIG_DISPLAY_BOARDINFO_LATE 2470 Similar to the previous option, but display this information 2471 later, once stdio is running and output goes to the LCD, if 2472 present. 2473 2474- CONFIG_BOARD_SIZE_LIMIT: 2475 Maximum size of the U-Boot image. When defined, the 2476 build system checks that the actual size does not 2477 exceed it. 2478 2479Low Level (hardware related) configuration options: 2480--------------------------------------------------- 2481 2482- CONFIG_SYS_CACHELINE_SIZE: 2483 Cache Line Size of the CPU. 2484 2485- CONFIG_SYS_CCSRBAR_DEFAULT: 2486 Default (power-on reset) physical address of CCSR on Freescale 2487 PowerPC SOCs. 2488 2489- CONFIG_SYS_CCSRBAR: 2490 Virtual address of CCSR. On a 32-bit build, this is typically 2491 the same value as CONFIG_SYS_CCSRBAR_DEFAULT. 2492 2493- CONFIG_SYS_CCSRBAR_PHYS: 2494 Physical address of CCSR. CCSR can be relocated to a new 2495 physical address, if desired. In this case, this macro should 2496 be set to that address. Otherwise, it should be set to the 2497 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR 2498 is typically relocated on 36-bit builds. It is recommended 2499 that this macro be defined via the _HIGH and _LOW macros: 2500 2501 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH 2502 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW) 2503 2504- CONFIG_SYS_CCSRBAR_PHYS_HIGH: 2505 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically 2506 either 0 (32-bit build) or 0xF (36-bit build). This macro is 2507 used in assembly code, so it must not contain typecasts or 2508 integer size suffixes (e.g. "ULL"). 2509 2510- CONFIG_SYS_CCSRBAR_PHYS_LOW: 2511 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is 2512 used in assembly code, so it must not contain typecasts or 2513 integer size suffixes (e.g. "ULL"). 2514 2515- CONFIG_SYS_CCSR_DO_NOT_RELOCATE: 2516 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be 2517 forced to a value that ensures that CCSR is not relocated. 2518 2519- CONFIG_IDE_AHB: 2520 Most IDE controllers were designed to be connected with PCI 2521 interface. Only few of them were designed for AHB interface. 2522 When software is doing ATA command and data transfer to 2523 IDE devices through IDE-AHB controller, some additional 2524 registers accessing to these kind of IDE-AHB controller 2525 is required. 2526 2527- CONFIG_SYS_IMMR: Physical address of the Internal Memory. 2528 DO NOT CHANGE unless you know exactly what you're 2529 doing! (11-4) [MPC8xx systems only] 2530 2531- CONFIG_SYS_INIT_RAM_ADDR: 2532 2533 Start address of memory area that can be used for 2534 initial data and stack; please note that this must be 2535 writable memory that is working WITHOUT special 2536 initialization, i. e. you CANNOT use normal RAM which 2537 will become available only after programming the 2538 memory controller and running certain initialization 2539 sequences. 2540 2541 U-Boot uses the following memory types: 2542 - MPC8xx: IMMR (internal memory of the CPU) 2543 2544- CONFIG_SYS_GBL_DATA_OFFSET: 2545 2546 Offset of the initial data structure in the memory 2547 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually 2548 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial 2549 data is located at the end of the available space 2550 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE - 2551 GENERATED_GBL_DATA_SIZE), and the initial stack is just 2552 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR + 2553 CONFIG_SYS_GBL_DATA_OFFSET) downward. 2554 2555 Note: 2556 On the MPC824X (or other systems that use the data 2557 cache for initial memory) the address chosen for 2558 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must 2559 point to an otherwise UNUSED address space between 2560 the top of RAM and the start of the PCI space. 2561 2562- CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27) 2563 2564- CONFIG_SYS_OR_TIMING_SDRAM: 2565 SDRAM timing 2566 2567- CONFIG_SYS_MAMR_PTA: 2568 periodic timer for refresh 2569 2570- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM, 2571 CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP, 2572 CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM, 2573 CONFIG_SYS_BR1_PRELIM: 2574 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH) 2575 2576- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE, 2577 CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM, 2578 CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM: 2579 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM) 2580 2581- CONFIG_SYS_SRIO: 2582 Chip has SRIO or not 2583 2584- CONFIG_SRIO1: 2585 Board has SRIO 1 port available 2586 2587- CONFIG_SRIO2: 2588 Board has SRIO 2 port available 2589 2590- CONFIG_SRIO_PCIE_BOOT_MASTER 2591 Board can support master function for Boot from SRIO and PCIE 2592 2593- CONFIG_SYS_SRIOn_MEM_VIRT: 2594 Virtual Address of SRIO port 'n' memory region 2595 2596- CONFIG_SYS_SRIOn_MEM_PHYxS: 2597 Physical Address of SRIO port 'n' memory region 2598 2599- CONFIG_SYS_SRIOn_MEM_SIZE: 2600 Size of SRIO port 'n' memory region 2601 2602- CONFIG_SYS_NAND_BUSWIDTH_16BIT 2603 Defined to tell the NAND controller that the NAND chip is using 2604 a 16 bit bus. 2605 Not all NAND drivers use this symbol. 2606 Example of drivers that use it: 2607 - drivers/mtd/nand/raw/ndfc.c 2608 - drivers/mtd/nand/raw/mxc_nand.c 2609 2610- CONFIG_SYS_NDFC_EBC0_CFG 2611 Sets the EBC0_CFG register for the NDFC. If not defined 2612 a default value will be used. 2613 2614- CONFIG_SPD_EEPROM 2615 Get DDR timing information from an I2C EEPROM. Common 2616 with pluggable memory modules such as SODIMMs 2617 2618 SPD_EEPROM_ADDRESS 2619 I2C address of the SPD EEPROM 2620 2621- CONFIG_SYS_SPD_BUS_NUM 2622 If SPD EEPROM is on an I2C bus other than the first 2623 one, specify here. Note that the value must resolve 2624 to something your driver can deal with. 2625 2626- CONFIG_SYS_DDR_RAW_TIMING 2627 Get DDR timing information from other than SPD. Common with 2628 soldered DDR chips onboard without SPD. DDR raw timing 2629 parameters are extracted from datasheet and hard-coded into 2630 header files or board specific files. 2631 2632- CONFIG_FSL_DDR_INTERACTIVE 2633 Enable interactive DDR debugging. See doc/README.fsl-ddr. 2634 2635- CONFIG_FSL_DDR_SYNC_REFRESH 2636 Enable sync of refresh for multiple controllers. 2637 2638- CONFIG_FSL_DDR_BIST 2639 Enable built-in memory test for Freescale DDR controllers. 2640 2641- CONFIG_SYS_83XX_DDR_USES_CS0 2642 Only for 83xx systems. If specified, then DDR should 2643 be configured using CS0 and CS1 instead of CS2 and CS3. 2644 2645- CONFIG_RMII 2646 Enable RMII mode for all FECs. 2647 Note that this is a global option, we can't 2648 have one FEC in standard MII mode and another in RMII mode. 2649 2650- CONFIG_CRC32_VERIFY 2651 Add a verify option to the crc32 command. 2652 The syntax is: 2653 2654 => crc32 -v <address> <count> <crc32> 2655 2656 Where address/count indicate a memory area 2657 and crc32 is the correct crc32 which the 2658 area should have. 2659 2660- CONFIG_LOOPW 2661 Add the "loopw" memory command. This only takes effect if 2662 the memory commands are activated globally (CONFIG_CMD_MEMORY). 2663 2664- CONFIG_CMD_MX_CYCLIC 2665 Add the "mdc" and "mwc" memory commands. These are cyclic 2666 "md/mw" commands. 2667 Examples: 2668 2669 => mdc.b 10 4 500 2670 This command will print 4 bytes (10,11,12,13) each 500 ms. 2671 2672 => mwc.l 100 12345678 10 2673 This command will write 12345678 to address 100 all 10 ms. 2674 2675 This only takes effect if the memory commands are activated 2676 globally (CONFIG_CMD_MEMORY). 2677 2678- CONFIG_SPL_BUILD 2679 Set when the currently-running compilation is for an artifact 2680 that will end up in the SPL (as opposed to the TPL or U-Boot 2681 proper). Code that needs stage-specific behavior should check 2682 this. 2683 2684- CONFIG_TPL_BUILD 2685 Set when the currently-running compilation is for an artifact 2686 that will end up in the TPL (as opposed to the SPL or U-Boot 2687 proper). Code that needs stage-specific behavior should check 2688 this. 2689 2690- CONFIG_SYS_MPC85XX_NO_RESETVEC 2691 Only for 85xx systems. If this variable is specified, the section 2692 .resetvec is not kept and the section .bootpg is placed in the 2693 previous 4k of the .text section. 2694 2695- CONFIG_ARCH_MAP_SYSMEM 2696 Generally U-Boot (and in particular the md command) uses 2697 effective address. It is therefore not necessary to regard 2698 U-Boot address as virtual addresses that need to be translated 2699 to physical addresses. However, sandbox requires this, since 2700 it maintains its own little RAM buffer which contains all 2701 addressable memory. This option causes some memory accesses 2702 to be mapped through map_sysmem() / unmap_sysmem(). 2703 2704- CONFIG_X86_RESET_VECTOR 2705 If defined, the x86 reset vector code is included. This is not 2706 needed when U-Boot is running from Coreboot. 2707 2708- CONFIG_SYS_NAND_NO_SUBPAGE_WRITE 2709 Option to disable subpage write in NAND driver 2710 driver that uses this: 2711 drivers/mtd/nand/raw/davinci_nand.c 2712 2713Freescale QE/FMAN Firmware Support: 2714----------------------------------- 2715 2716The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the 2717loading of "firmware", which is encoded in the QE firmware binary format. 2718This firmware often needs to be loaded during U-Boot booting, so macros 2719are used to identify the storage device (NOR flash, SPI, etc) and the address 2720within that device. 2721 2722- CONFIG_SYS_FMAN_FW_ADDR 2723 The address in the storage device where the FMAN microcode is located. The 2724 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro 2725 is also specified. 2726 2727- CONFIG_SYS_QE_FW_ADDR 2728 The address in the storage device where the QE microcode is located. The 2729 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro 2730 is also specified. 2731 2732- CONFIG_SYS_QE_FMAN_FW_LENGTH 2733 The maximum possible size of the firmware. The firmware binary format 2734 has a field that specifies the actual size of the firmware, but it 2735 might not be possible to read any part of the firmware unless some 2736 local storage is allocated to hold the entire firmware first. 2737 2738- CONFIG_SYS_QE_FMAN_FW_IN_NOR 2739 Specifies that QE/FMAN firmware is located in NOR flash, mapped as 2740 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the 2741 virtual address in NOR flash. 2742 2743- CONFIG_SYS_QE_FMAN_FW_IN_NAND 2744 Specifies that QE/FMAN firmware is located in NAND flash. 2745 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash. 2746 2747- CONFIG_SYS_QE_FMAN_FW_IN_MMC 2748 Specifies that QE/FMAN firmware is located on the primary SD/MMC 2749 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device. 2750 2751- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE 2752 Specifies that QE/FMAN firmware is located in the remote (master) 2753 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which 2754 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound 2755 window->master inbound window->master LAW->the ucode address in 2756 master's memory space. 2757 2758Freescale Layerscape Management Complex Firmware Support: 2759--------------------------------------------------------- 2760The Freescale Layerscape Management Complex (MC) supports the loading of 2761"firmware". 2762This firmware often needs to be loaded during U-Boot booting, so macros 2763are used to identify the storage device (NOR flash, SPI, etc) and the address 2764within that device. 2765 2766- CONFIG_FSL_MC_ENET 2767 Enable the MC driver for Layerscape SoCs. 2768 2769Freescale Layerscape Debug Server Support: 2770------------------------------------------- 2771The Freescale Layerscape Debug Server Support supports the loading of 2772"Debug Server firmware" and triggering SP boot-rom. 2773This firmware often needs to be loaded during U-Boot booting. 2774 2775- CONFIG_SYS_MC_RSV_MEM_ALIGN 2776 Define alignment of reserved memory MC requires 2777 2778Reproducible builds 2779------------------- 2780 2781In order to achieve reproducible builds, timestamps used in the U-Boot build 2782process have to be set to a fixed value. 2783 2784This is done using the SOURCE_DATE_EPOCH environment variable. 2785SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration 2786option for U-Boot or an environment variable in U-Boot. 2787 2788SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC. 2789 2790Building the Software: 2791====================== 2792 2793Building U-Boot has been tested in several native build environments 2794and in many different cross environments. Of course we cannot support 2795all possibly existing versions of cross development tools in all 2796(potentially obsolete) versions. In case of tool chain problems we 2797recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK) 2798which is extensively used to build and test U-Boot. 2799 2800If you are not using a native environment, it is assumed that you 2801have GNU cross compiling tools available in your path. In this case, 2802you must set the environment variable CROSS_COMPILE in your shell. 2803Note that no changes to the Makefile or any other source files are 2804necessary. For example using the ELDK on a 4xx CPU, please enter: 2805 2806 $ CROSS_COMPILE=ppc_4xx- 2807 $ export CROSS_COMPILE 2808 2809U-Boot is intended to be simple to build. After installing the 2810sources you must configure U-Boot for one specific board type. This 2811is done by typing: 2812 2813 make NAME_defconfig 2814 2815where "NAME_defconfig" is the name of one of the existing configu- 2816rations; see configs/*_defconfig for supported names. 2817 2818Note: for some boards special configuration names may exist; check if 2819 additional information is available from the board vendor; for 2820 instance, the TQM823L systems are available without (standard) 2821 or with LCD support. You can select such additional "features" 2822 when choosing the configuration, i. e. 2823 2824 make TQM823L_defconfig 2825 - will configure for a plain TQM823L, i. e. no LCD support 2826 2827 make TQM823L_LCD_defconfig 2828 - will configure for a TQM823L with U-Boot console on LCD 2829 2830 etc. 2831 2832 2833Finally, type "make all", and you should get some working U-Boot 2834images ready for download to / installation on your system: 2835 2836- "u-boot.bin" is a raw binary image 2837- "u-boot" is an image in ELF binary format 2838- "u-boot.srec" is in Motorola S-Record format 2839 2840By default the build is performed locally and the objects are saved 2841in the source directory. One of the two methods can be used to change 2842this behavior and build U-Boot to some external directory: 2843 28441. Add O= to the make command line invocations: 2845 2846 make O=/tmp/build distclean 2847 make O=/tmp/build NAME_defconfig 2848 make O=/tmp/build all 2849 28502. Set environment variable KBUILD_OUTPUT to point to the desired location: 2851 2852 export KBUILD_OUTPUT=/tmp/build 2853 make distclean 2854 make NAME_defconfig 2855 make all 2856 2857Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment 2858variable. 2859 2860User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by 2861setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS. 2862For example to treat all compiler warnings as errors: 2863 2864 make KCFLAGS=-Werror 2865 2866Please be aware that the Makefiles assume you are using GNU make, so 2867for instance on NetBSD you might need to use "gmake" instead of 2868native "make". 2869 2870 2871If the system board that you have is not listed, then you will need 2872to port U-Boot to your hardware platform. To do this, follow these 2873steps: 2874 28751. Create a new directory to hold your board specific code. Add any 2876 files you need. In your board directory, you will need at least 2877 the "Makefile" and a "<board>.c". 28782. Create a new configuration file "include/configs/<board>.h" for 2879 your board. 28803. If you're porting U-Boot to a new CPU, then also create a new 2881 directory to hold your CPU specific code. Add any files you need. 28824. Run "make <board>_defconfig" with your new name. 28835. Type "make", and you should get a working "u-boot.srec" file 2884 to be installed on your target system. 28856. Debug and solve any problems that might arise. 2886 [Of course, this last step is much harder than it sounds.] 2887 2888 2889Testing of U-Boot Modifications, Ports to New Hardware, etc.: 2890============================================================== 2891 2892If you have modified U-Boot sources (for instance added a new board 2893or support for new devices, a new CPU, etc.) you are expected to 2894provide feedback to the other developers. The feedback normally takes 2895the form of a "patch", i.e. a context diff against a certain (latest 2896official or latest in the git repository) version of U-Boot sources. 2897 2898But before you submit such a patch, please verify that your modifi- 2899cation did not break existing code. At least make sure that *ALL* of 2900the supported boards compile WITHOUT ANY compiler warnings. To do so, 2901just run the buildman script (tools/buildman/buildman), which will 2902configure and build U-Boot for ALL supported system. Be warned, this 2903will take a while. Please see the buildman README, or run 'buildman -H' 2904for documentation. 2905 2906 2907See also "U-Boot Porting Guide" below. 2908 2909 2910Monitor Commands - Overview: 2911============================ 2912 2913go - start application at address 'addr' 2914run - run commands in an environment variable 2915bootm - boot application image from memory 2916bootp - boot image via network using BootP/TFTP protocol 2917bootz - boot zImage from memory 2918tftpboot- boot image via network using TFTP protocol 2919 and env variables "ipaddr" and "serverip" 2920 (and eventually "gatewayip") 2921tftpput - upload a file via network using TFTP protocol 2922rarpboot- boot image via network using RARP/TFTP protocol 2923diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd' 2924loads - load S-Record file over serial line 2925loadb - load binary file over serial line (kermit mode) 2926md - memory display 2927mm - memory modify (auto-incrementing) 2928nm - memory modify (constant address) 2929mw - memory write (fill) 2930ms - memory search 2931cp - memory copy 2932cmp - memory compare 2933crc32 - checksum calculation 2934i2c - I2C sub-system 2935sspi - SPI utility commands 2936base - print or set address offset 2937printenv- print environment variables 2938pwm - control pwm channels 2939setenv - set environment variables 2940saveenv - save environment variables to persistent storage 2941protect - enable or disable FLASH write protection 2942erase - erase FLASH memory 2943flinfo - print FLASH memory information 2944nand - NAND memory operations (see doc/README.nand) 2945bdinfo - print Board Info structure 2946iminfo - print header information for application image 2947coninfo - print console devices and informations 2948ide - IDE sub-system 2949loop - infinite loop on address range 2950loopw - infinite write loop on address range 2951mtest - simple RAM test 2952icache - enable or disable instruction cache 2953dcache - enable or disable data cache 2954reset - Perform RESET of the CPU 2955echo - echo args to console 2956version - print monitor version 2957help - print online help 2958? - alias for 'help' 2959 2960 2961Monitor Commands - Detailed Description: 2962======================================== 2963 2964TODO. 2965 2966For now: just type "help <command>". 2967 2968 2969Environment Variables: 2970====================== 2971 2972U-Boot supports user configuration using Environment Variables which 2973can be made persistent by saving to Flash memory. 2974 2975Environment Variables are set using "setenv", printed using 2976"printenv", and saved to Flash using "saveenv". Using "setenv" 2977without a value can be used to delete a variable from the 2978environment. As long as you don't save the environment you are 2979working with an in-memory copy. In case the Flash area containing the 2980environment is erased by accident, a default environment is provided. 2981 2982Some configuration options can be set using Environment Variables. 2983 2984List of environment variables (most likely not complete): 2985 2986 baudrate - see CONFIG_BAUDRATE 2987 2988 bootdelay - see CONFIG_BOOTDELAY 2989 2990 bootcmd - see CONFIG_BOOTCOMMAND 2991 2992 bootargs - Boot arguments when booting an RTOS image 2993 2994 bootfile - Name of the image to load with TFTP 2995 2996 bootm_low - Memory range available for image processing in the bootm 2997 command can be restricted. This variable is given as 2998 a hexadecimal number and defines lowest address allowed 2999 for use by the bootm command. See also "bootm_size" 3000 environment variable. Address defined by "bootm_low" is
3001 also the base of the initial memory mapping for the Linux 3002 kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and 3003 bootm_mapsize. 3004 3005 bootm_mapsize - Size of the initial memory mapping for the Linux kernel. 3006 This variable is given as a hexadecimal number and it 3007 defines the size of the memory region starting at base 3008 address bootm_low that is accessible by the Linux kernel 3009 during early boot. If unset, CONFIG_SYS_BOOTMAPSZ is used 3010 as the default value if it is defined, and bootm_size is 3011 used otherwise. 3012 3013 bootm_size - Memory range available for image processing in the bootm 3014 command can be restricted. This variable is given as 3015 a hexadecimal number and defines the size of the region 3016 allowed for use by the bootm command. See also "bootm_low" 3017 environment variable. 3018 3019 bootstopkeysha256, bootdelaykey, bootstopkey - See README.autoboot 3020 3021 updatefile - Location of the software update file on a TFTP server, used 3022 by the automatic software update feature. Please refer to 3023 documentation in doc/README.update for more details. 3024 3025 autoload - if set to "no" (any string beginning with 'n'), 3026 "bootp" will just load perform a lookup of the 3027 configuration from the BOOTP server, but not try to 3028 load any image using TFTP 3029 3030 autostart - if set to "yes", an image loaded using the "bootp", 3031 "rarpboot", "tftpboot" or "diskboot" commands will 3032 be automatically started (by internally calling 3033 "bootm") 3034 3035 If set to "no", a standalone image passed to the 3036 "bootm" command will be copied to the load address 3037 (and eventually uncompressed), but NOT be started. 3038 This can be used to load and uncompress arbitrary 3039 data. 3040 3041 fdt_high - if set this restricts the maximum address that the 3042 flattened device tree will be copied into upon boot. 3043 For example, if you have a system with 1 GB memory 3044 at physical address 0x10000000, while Linux kernel 3045 only recognizes the first 704 MB as low memory, you 3046 may need to set fdt_high as 0x3C000000 to have the 3047 device tree blob be copied to the maximum address 3048 of the 704 MB low memory, so that Linux kernel can 3049 access it during the boot procedure. 3050 3051 If this is set to the special value 0xFFFFFFFF then 3052 the fdt will not be copied at all on boot. For this 3053 to work it must reside in writable memory, have 3054 sufficient padding on the end of it for u-boot to 3055 add the information it needs into it, and the memory 3056 must be accessible by the kernel. 3057 3058 fdtcontroladdr- if set this is the address of the control flattened 3059 device tree used by U-Boot when CONFIG_OF_CONTROL is 3060 defined. 3061 3062 i2cfast - (PPC405GP|PPC405EP only) 3063 if set to 'y' configures Linux I2C driver for fast 3064 mode (400kHZ). This environment variable is used in 3065 initialization code. So, for changes to be effective 3066 it must be saved and board must be reset. 3067 3068 initrd_high - restrict positioning of initrd images: 3069 If this variable is not set, initrd images will be 3070 copied to the highest possible address in RAM; this 3071 is usually what you want since it allows for 3072 maximum initrd size. If for some reason you want to 3073 make sure that the initrd image is loaded below the 3074 CONFIG_SYS_BOOTMAPSZ limit, you can set this environment 3075 variable to a value of "no" or "off" or "0". 3076 Alternatively, you can set it to a maximum upper 3077 address to use (U-Boot will still check that it 3078 does not overwrite the U-Boot stack and data). 3079 3080 For instance, when you have a system with 16 MB 3081 RAM, and want to reserve 4 MB from use by Linux, 3082 you can do this by adding "mem=12M" to the value of 3083 the "bootargs" variable. However, now you must make 3084 sure that the initrd image is placed in the first 3085 12 MB as well - this can be done with 3086 3087 setenv initrd_high 00c00000 3088 3089 If you set initrd_high to 0xFFFFFFFF, this is an 3090 indication to U-Boot that all addresses are legal 3091 for the Linux kernel, including addresses in flash 3092 memory. In this case U-Boot will NOT COPY the 3093 ramdisk at all. This may be useful to reduce the 3094 boot time on your system, but requires that this 3095 feature is supported by your Linux kernel. 3096 3097 ipaddr - IP address; needed for tftpboot command 3098 3099 loadaddr - Default load address for commands like "bootp", 3100 "rarpboot", "tftpboot", "loadb" or "diskboot" 3101 3102 loads_echo - see CONFIG_LOADS_ECHO 3103 3104 serverip - TFTP server IP address; needed for tftpboot command 3105 3106 bootretry - see CONFIG_BOOT_RETRY_TIME 3107 3108 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR 3109 3110 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR 3111 3112 ethprime - controls which interface is used first. 3113 3114 ethact - controls which interface is currently active. 3115 For example you can do the following 3116 3117 => setenv ethact FEC 3118 => ping 192.168.0.1 # traffic sent on FEC 3119 => setenv ethact SCC 3120 => ping 10.0.0.1 # traffic sent on SCC 3121 3122 ethrotate - When set to "no" U-Boot does not go through all 3123 available network interfaces. 3124 It just stays at the currently selected interface. 3125 3126 netretry - When set to "no" each network operation will 3127 either succeed or fail without retrying. 3128 When set to "once" the network operation will 3129 fail when all the available network interfaces 3130 are tried once without success. 3131 Useful on scripts which control the retry operation 3132 themselves. 3133 3134 npe_ucode - set load address for the NPE microcode 3135 3136 silent_linux - If set then Linux will be told to boot silently, by 3137 changing the console to be empty. If "yes" it will be 3138 made silent. If "no" it will not be made silent. If 3139 unset, then it will be made silent if the U-Boot console 3140 is silent. 3141 3142 tftpsrcp - If this is set, the value is used for TFTP's 3143 UDP source port. 3144 3145 tftpdstp - If this is set, the value is used for TFTP's UDP 3146 destination port instead of the Well Know Port 69. 3147 3148 tftpblocksize - Block size to use for TFTP transfers; if not set, 3149 we use the TFTP server's default block size 3150 3151 tftptimeout - Retransmission timeout for TFTP packets (in milli- 3152 seconds, minimum value is 1000 = 1 second). Defines 3153 when a packet is considered to be lost so it has to 3154 be retransmitted. The default is 5000 = 5 seconds. 3155 Lowering this value may make downloads succeed 3156 faster in networks with high packet loss rates or 3157 with unreliable TFTP servers. 3158 3159 tftptimeoutcountmax - maximum count of TFTP timeouts (no 3160 unit, minimum value = 0). Defines how many timeouts 3161 can happen during a single file transfer before that 3162 transfer is aborted. The default is 10, and 0 means 3163 'no timeouts allowed'. Increasing this value may help 3164 downloads succeed with high packet loss rates, or with 3165 unreliable TFTP servers or client hardware. 3166 3167 tftpwindowsize - if this is set, the value is used for TFTP's 3168 window size as described by RFC 7440. 3169 This means the count of blocks we can receive before 3170 sending ack to server. 3171 3172 vlan - When set to a value < 4095 the traffic over 3173 Ethernet is encapsulated/received over 802.1q 3174 VLAN tagged frames. 3175 3176 bootpretryperiod - Period during which BOOTP/DHCP sends retries. 3177 Unsigned value, in milliseconds. If not set, the period will 3178 be either the default (28000), or a value based on 3179 CONFIG_NET_RETRY_COUNT, if defined. This value has 3180 precedence over the valu based on CONFIG_NET_RETRY_COUNT. 3181 3182 memmatches - Number of matches found by the last 'ms' command, in hex 3183 3184 memaddr - Address of the last match found by the 'ms' command, in hex, 3185 or 0 if none 3186 3187 mempos - Index position of the last match found by the 'ms' command, 3188 in units of the size (.b, .w, .l) of the search 3189 3190 zbootbase - (x86 only) Base address of the bzImage 'setup' block 3191 3192 zbootaddr - (x86 only) Address of the loaded bzImage, typically 3193 BZIMAGE_LOAD_ADDR which is 0x100000 3194 3195The following image location variables contain the location of images 3196used in booting. The "Image" column gives the role of the image and is 3197not an environment variable name. The other columns are environment 3198variable names. "File Name" gives the name of the file on a TFTP 3199server, "RAM Address" gives the location in RAM the image will be 3200loaded to, and "Flash Location" gives the image's address in NOR 3201flash or offset in NAND flash. 3202 3203*Note* - these variables don't have to be defined for all boards, some 3204boards currently use other variables for these purposes, and some 3205boards use these variables for other purposes. 3206 3207Image File Name RAM Address Flash Location 3208----- --------- ----------- -------------- 3209u-boot u-boot u-boot_addr_r u-boot_addr 3210Linux kernel bootfile kernel_addr_r kernel_addr 3211device tree blob fdtfile fdt_addr_r fdt_addr 3212ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr 3213 3214The following environment variables may be used and automatically 3215updated by the network boot commands ("bootp" and "rarpboot"), 3216depending the information provided by your boot server: 3217 3218 bootfile - see above 3219 dnsip - IP address of your Domain Name Server 3220 dnsip2 - IP address of your secondary Domain Name Server 3221 gatewayip - IP address of the Gateway (Router) to use 3222 hostname - Target hostname 3223 ipaddr - see above 3224 netmask - Subnet Mask 3225 rootpath - Pathname of the root filesystem on the NFS server 3226 serverip - see above 3227 3228 3229There are two special Environment Variables: 3230 3231 serial# - contains hardware identification information such 3232 as type string and/or serial number 3233 ethaddr - Ethernet address 3234 3235These variables can be set only once (usually during manufacturing of 3236the board). U-Boot refuses to delete or overwrite these variables 3237once they have been set once. 3238 3239 3240Further special Environment Variables: 3241 3242 ver - Contains the U-Boot version string as printed 3243 with the "version" command. This variable is 3244 readonly (see CONFIG_VERSION_VARIABLE). 3245 3246 3247Please note that changes to some configuration parameters may take 3248only effect after the next boot (yes, that's just like Windoze :-). 3249 3250 3251Callback functions for environment variables: 3252--------------------------------------------- 3253 3254For some environment variables, the behavior of u-boot needs to change 3255when their values are changed. This functionality allows functions to 3256be associated with arbitrary variables. On creation, overwrite, or 3257deletion, the callback will provide the opportunity for some side 3258effect to happen or for the change to be rejected. 3259 3260The callbacks are named and associated with a function using the 3261U_BOOT_ENV_CALLBACK macro in your board or driver code. 3262 3263These callbacks are associated with variables in one of two ways. The 3264static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC 3265in the board configuration to a string that defines a list of 3266associations. The list must be in the following format: 3267 3268 entry = variable_name[:callback_name] 3269 list = entry[,list] 3270 3271If the callback name is not specified, then the callback is deleted. 3272Spaces are also allowed anywhere in the list. 3273 3274Callbacks can also be associated by defining the ".callbacks" variable 3275with the same list format above. Any association in ".callbacks" will 3276override any association in the static list. You can define 3277CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the 3278".callbacks" environment variable in the default or embedded environment. 3279 3280If CONFIG_REGEX is defined, the variable_name above is evaluated as a 3281regular expression. This allows multiple variables to be connected to 3282the same callback without explicitly listing them all out. 3283 3284The signature of the callback functions is: 3285 3286 int callback(const char *name, const char *value, enum env_op op, int flags) 3287 3288* name - changed environment variable 3289* value - new value of the environment variable 3290* op - operation (create, overwrite, or delete) 3291* flags - attributes of the environment variable change, see flags H_* in 3292 include/search.h 3293 3294The return value is 0 if the variable change is accepted and 1 otherwise. 3295 3296 3297Note for Redundant Ethernet Interfaces: 3298======================================= 3299 3300Some boards come with redundant Ethernet interfaces; U-Boot supports 3301such configurations and is capable of automatic selection of a 3302"working" interface when needed. MAC assignment works as follows: 3303 3304Network interfaces are numbered eth0, eth1, eth2, ... Corresponding 3305MAC addresses can be stored in the environment as "ethaddr" (=>eth0), 3306"eth1addr" (=>eth1), "eth2addr", ... 3307 3308If the network interface stores some valid MAC address (for instance 3309in SROM), this is used as default address if there is NO correspon- 3310ding setting in the environment; if the corresponding environment 3311variable is set, this overrides the settings in the card; that means: 3312 3313o If the SROM has a valid MAC address, and there is no address in the 3314 environment, the SROM's address is used. 3315 3316o If there is no valid address in the SROM, and a definition in the 3317 environment exists, then the value from the environment variable is 3318 used. 3319 3320o If both the SROM and the environment contain a MAC address, and 3321 both addresses are the same, this MAC address is used. 3322 3323o If both the SROM and the environment contain a MAC address, and the 3324 addresses differ, the value from the environment is used and a 3325 warning is printed. 3326 3327o If neither SROM nor the environment contain a MAC address, an error 3328 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case 3329 a random, locally-assigned MAC is used. 3330 3331If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses 3332will be programmed into hardware as part of the initialization process. This 3333may be skipped by setting the appropriate 'ethmacskip' environment variable. 3334The naming convention is as follows: 3335"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc. 3336 3337Image Formats: 3338============== 3339 3340U-Boot is capable of booting (and performing other auxiliary operations on) 3341images in two formats: 3342 3343New uImage format (FIT) 3344----------------------- 3345 3346Flexible and powerful format based on Flattened Image Tree -- FIT (similar 3347to Flattened Device Tree). It allows the use of images with multiple 3348components (several kernels, ramdisks, etc.), with contents protected by 3349SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory. 3350 3351 3352Old uImage format 3353----------------- 3354 3355Old image format is based on binary files which can be basically anything, 3356preceded by a special header; see the definitions in include/image.h for 3357details; basically, the header defines the following image properties: 3358 3359* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD, 3360 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks, 3361 LynxOS, pSOS, QNX, RTEMS, INTEGRITY; 3362 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS, 3363 INTEGRITY). 3364* Target CPU Architecture (Provisions for Alpha, ARM, Intel x86, 3365 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit; 3366 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC). 3367* Compression Type (uncompressed, gzip, bzip2) 3368* Load Address 3369* Entry Point 3370* Image Name 3371* Image Timestamp 3372 3373The header is marked by a special Magic Number, and both the header 3374and the data portions of the image are secured against corruption by 3375CRC32 checksums. 3376 3377 3378Linux Support: 3379============== 3380 3381Although U-Boot should support any OS or standalone application 3382easily, the main focus has always been on Linux during the design of 3383U-Boot. 3384 3385U-Boot includes many features that so far have been part of some 3386special "boot loader" code within the Linux kernel. Also, any 3387"initrd" images to be used are no longer part of one big Linux image; 3388instead, kernel and "initrd" are separate images. This implementation 3389serves several purposes: 3390 3391- the same features can be used for other OS or standalone 3392 applications (for instance: using compressed images to reduce the 3393 Flash memory footprint) 3394 3395- it becomes much easier to port new Linux kernel versions because 3396 lots of low-level, hardware dependent stuff are done by U-Boot 3397 3398- the same Linux kernel image can now be used with different "initrd" 3399 images; of course this also means that different kernel images can 3400 be run with the same "initrd". This makes testing easier (you don't 3401 have to build a new "zImage.initrd" Linux image when you just 3402 change a file in your "initrd"). Also, a field-upgrade of the 3403 software is easier now. 3404 3405 3406Linux HOWTO: 3407============ 3408 3409Porting Linux to U-Boot based systems: 3410--------------------------------------- 3411 3412U-Boot cannot save you from doing all the necessary modifications to 3413configure the Linux device drivers for use with your target hardware 3414(no, we don't intend to provide a full virtual machine interface to 3415Linux :-). 3416 3417But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot). 3418 3419Just make sure your machine specific header file (for instance 3420include/asm-ppc/tqm8xx.h) includes the same definition of the Board 3421Information structure as we define in include/asm-<arch>/u-boot.h, 3422and make sure that your definition of IMAP_ADDR uses the same value 3423as your U-Boot configuration in CONFIG_SYS_IMMR. 3424 3425Note that U-Boot now has a driver model, a unified model for drivers. 3426If you are adding a new driver, plumb it into driver model. If there 3427is no uclass available, you are encouraged to create one. See 3428doc/driver-model. 3429 3430 3431Configuring the Linux kernel: 3432----------------------------- 3433 3434No specific requirements for U-Boot. Make sure you have some root 3435device (initial ramdisk, NFS) for your target system. 3436 3437 3438Building a Linux Image: 3439----------------------- 3440 3441With U-Boot, "normal" build targets like "zImage" or "bzImage" are 3442not used. If you use recent kernel source, a new build target 3443"uImage" will exist which automatically builds an image usable by 3444U-Boot. Most older kernels also have support for a "pImage" target, 3445which was introduced for our predecessor project PPCBoot and uses a 3446100% compatible format. 3447 3448Example: 3449 3450 make TQM850L_defconfig 3451 make oldconfig 3452 make dep 3453 make uImage 3454 3455The "uImage" build target uses a special tool (in 'tools/mkimage') to 3456encapsulate a compressed Linux kernel image with header information, 3457CRC32 checksum etc. for use with U-Boot. This is what we are doing: 3458 3459* build a standard "vmlinux" kernel image (in ELF binary format): 3460 3461* convert the kernel into a raw binary image: 3462 3463 ${CROSS_COMPILE}-objcopy -O binary \ 3464 -R .note -R .comment \ 3465 -S vmlinux linux.bin 3466 3467* compress the binary image: 3468 3469 gzip -9 linux.bin 3470 3471* package compressed binary image for U-Boot: 3472 3473 mkimage -A ppc -O linux -T kernel -C gzip \ 3474 -a 0 -e 0 -n "Linux Kernel Image" \ 3475 -d linux.bin.gz uImage 3476 3477 3478The "mkimage" tool can also be used to create ramdisk images for use 3479with U-Boot, either separated from the Linux kernel image, or 3480combined into one file. "mkimage" encapsulates the images with a 64 3481byte header containing information about target architecture, 3482operating system, image type, compression method, entry points, time 3483stamp, CRC32 checksums, etc. 3484 3485"mkimage" can be called in two ways: to verify existing images and 3486print the header information, or to build new images. 3487 3488In the first form (with "-l" option) mkimage lists the information 3489contained in the header of an existing U-Boot image; this includes 3490checksum verification: 3491 3492 tools/mkimage -l image 3493 -l ==> list image header information 3494 3495The second form (with "-d" option) is used to build a U-Boot image 3496from a "data file" which is used as image payload: 3497 3498 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \ 3499 -n name -d data_file image 3500 -A ==> set architecture to 'arch' 3501 -O ==> set operating system to 'os' 3502 -T ==> set image type to 'type' 3503 -C ==> set compression type 'comp' 3504 -a ==> set load address to 'addr' (hex) 3505 -e ==> set entry point to 'ep' (hex) 3506 -n ==> set image name to 'name' 3507 -d ==> use image data from 'datafile' 3508 3509Right now, all Linux kernels for PowerPC systems use the same load 3510address (0x00000000), but the entry point address depends on the 3511kernel version: 3512 3513- 2.2.x kernels have the entry point at 0x0000000C, 3514- 2.3.x and later kernels have the entry point at 0x00000000. 3515 3516So a typical call to build a U-Boot image would read: 3517 3518 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \ 3519 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \ 3520 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \ 3521 > examples/uImage.TQM850L 3522 Image Name: 2.4.4 kernel for TQM850L 3523 Created: Wed Jul 19 02:34:59 2000 3524 Image Type: PowerPC Linux Kernel Image (gzip compressed) 3525 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB 3526 Load Address: 0x00000000 3527 Entry Point: 0x00000000 3528 3529To verify the contents of the image (or check for corruption): 3530 3531 -> tools/mkimage -l examples/uImage.TQM850L 3532 Image Name: 2.4.4 kernel for TQM850L 3533 Created: Wed Jul 19 02:34:59 2000 3534 Image Type: PowerPC Linux Kernel Image (gzip compressed) 3535 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB 3536 Load Address: 0x00000000 3537 Entry Point: 0x00000000 3538 3539NOTE: for embedded systems where boot time is critical you can trade 3540speed for memory and install an UNCOMPRESSED image instead: this 3541needs more space in Flash, but boots much faster since it does not 3542need to be uncompressed: 3543 3544 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz 3545 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \ 3546 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \ 3547 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \ 3548 > examples/uImage.TQM850L-uncompressed 3549 Image Name: 2.4.4 kernel for TQM850L 3550 Created: Wed Jul 19 02:34:59 2000 3551 Image Type: PowerPC Linux Kernel Image (uncompressed) 3552 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB 3553 Load Address: 0x00000000 3554 Entry Point: 0x00000000 3555 3556 3557Similar you can build U-Boot images from a 'ramdisk.image.gz' file 3558when your kernel is intended to use an initial ramdisk: 3559 3560 -> tools/mkimage -n 'Simple Ramdisk Image' \ 3561 > -A ppc -O linux -T ramdisk -C gzip \ 3562 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd 3563 Image Name: Simple Ramdisk Image 3564 Created: Wed Jan 12 14:01:50 2000 3565 Image Type: PowerPC Linux RAMDisk Image (gzip compressed) 3566 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB 3567 Load Address: 0x00000000 3568 Entry Point: 0x00000000 3569 3570The "dumpimage" tool can be used to disassemble or list the contents of images 3571built by mkimage. See dumpimage's help output (-h) for details. 3572 3573Installing a Linux Image: 3574------------------------- 3575 3576To downloading a U-Boot image over the serial (console) interface, 3577you must convert the image to S-Record format: 3578 3579 objcopy -I binary -O srec examples/image examples/image.srec 3580 3581The 'objcopy' does not understand the information in the U-Boot 3582image header, so the resulting S-Record file will be relative to 3583address 0x00000000. To load it to a given address, you need to 3584specify the target address as 'offset' parameter with the 'loads' 3585command. 3586 3587Example: install the image to address 0x40100000 (which on the 3588TQM8xxL is in the first Flash bank): 3589 3590 => erase 40100000 401FFFFF 3591 3592 .......... done 3593 Erased 8 sectors 3594 3595 => loads 40100000 3596 ## Ready for S-Record download ... 3597 ~>examples/image.srec 3598 1 2 3 4 5 6 7 8 9 10 11 12 13 ... 3599 ... 3600 15989 15990 15991 15992 3601 [file transfer complete] 3602 [connected] 3603 ## Start Addr = 0x00000000 3604 3605 3606You can check the success of the download using the 'iminfo' command; 3607this includes a checksum verification so you can be sure no data 3608corruption happened: 3609 3610 => imi 40100000 3611 3612 ## Checking Image at 40100000 ... 3613 Image Name: 2.2.13 for initrd on TQM850L 3614 Image Type: PowerPC Linux Kernel Image (gzip compressed) 3615 Data Size: 335725 Bytes = 327 kB = 0 MB 3616 Load Address: 00000000 3617 Entry Point: 0000000c 3618 Verifying Checksum ... OK 3619 3620 3621Boot Linux: 3622----------- 3623 3624The "bootm" command is used to boot an application that is stored in 3625memory (RAM or Flash). In case of a Linux kernel image, the contents 3626of the "bootargs" environment variable is passed to the kernel as 3627parameters. You can check and modify this variable using the 3628"printenv" and "setenv" commands: 3629 3630 3631 => printenv bootargs 3632 bootargs=root=/dev/ram 3633 3634 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2 3635 3636 => printenv bootargs 3637 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2 3638 3639 => bootm 40020000 3640 ## Booting Linux kernel at 40020000 ... 3641 Image Name: 2.2.13 for NFS on TQM850L 3642 Image Type: PowerPC Linux Kernel Image (gzip compressed) 3643 Data Size: 381681 Bytes = 372 kB = 0 MB 3644 Load Address: 00000000 3645 Entry Point: 0000000c 3646 Verifying Checksum ... OK 3647 Uncompressing Kernel Image ... OK 3648 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 3649 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2 3650 time_init: decrementer frequency = 187500000/60 3651 Calibrating delay loop... 49.77 BogoMIPS 3652 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000] 3653 ... 3654 3655If you want to boot a Linux kernel with initial RAM disk, you pass 3656the memory addresses of both the kernel and the initrd image (PPBCOOT 3657format!) to the "bootm" command: 3658 3659 => imi 40100000 40200000 3660 3661 ## Checking Image at 40100000 ... 3662 Image Name: 2.2.13 for initrd on TQM850L 3663 Image Type: PowerPC Linux Kernel Image (gzip compressed) 3664 Data Size: 335725 Bytes = 327 kB = 0 MB 3665 Load Address: 00000000 3666 Entry Point: 0000000c 3667 Verifying Checksum ... OK 3668 3669 ## Checking Image at 40200000 ... 3670 Image Name: Simple Ramdisk Image 3671 Image Type: PowerPC Linux RAMDisk Image (gzip compressed) 3672 Data Size: 566530 Bytes = 553 kB = 0 MB 3673 Load Address: 00000000 3674 Entry Point: 00000000 3675 Verifying Checksum ... OK 3676 3677 => bootm 40100000 40200000 3678 ## Booting Linux kernel at 40100000 ... 3679 Image Name: 2.2.13 for initrd on TQM850L 3680 Image Type: PowerPC Linux Kernel Image (gzip compressed) 3681 Data Size: 335725 Bytes = 327 kB = 0 MB 3682 Load Address: 00000000 3683 Entry Point: 0000000c 3684 Verifying Checksum ... OK 3685 Uncompressing Kernel Image ... OK 3686 ## Loading RAMDisk Image at 40200000 ... 3687 Image Name: Simple Ramdisk Image 3688 Image Type: PowerPC Linux RAMDisk Image (gzip compressed) 3689 Data Size: 566530 Bytes = 553 kB = 0 MB 3690 Load Address: 00000000 3691 Entry Point: 00000000 3692 Verifying Checksum ... OK 3693 Loading Ramdisk ... OK 3694 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 3695 Boot arguments: root=/dev/ram 3696 time_init: decrementer frequency = 187500000/60 3697 Calibrating delay loop... 49.77 BogoMIPS 3698 ... 3699 RAMDISK: Compressed image found at block 0 3700 VFS: Mounted root (ext2 filesystem). 3701 3702 bash# 3703 3704Boot Linux and pass a flat device tree: 3705----------- 3706 3707First, U-Boot must be compiled with the appropriate defines. See the section 3708titled "Linux Kernel Interface" above for a more in depth explanation. The 3709following is an example of how to start a kernel and pass an updated 3710flat device tree: 3711 3712=> print oftaddr 3713oftaddr=0x300000 3714=> print oft 3715oft=oftrees/mpc8540ads.dtb 3716=> tftp $oftaddr $oft 3717Speed: 1000, full duplex 3718Using TSEC0 device 3719TFTP from server 192.168.1.1; our IP address is 192.168.1.101 3720Filename 'oftrees/mpc8540ads.dtb'. 3721Load address: 0x300000 3722Loading: # 3723done 3724Bytes transferred = 4106 (100a hex) 3725=> tftp $loadaddr $bootfile 3726Speed: 1000, full duplex 3727Using TSEC0 device 3728TFTP from server 192.168.1.1; our IP address is 192.168.1.2 3729Filename 'uImage'. 3730Load address: 0x200000 3731Loading:############ 3732done 3733Bytes transferred = 1029407 (fb51f hex) 3734=> print loadaddr 3735loadaddr=200000 3736=> print oftaddr 3737oftaddr=0x300000 3738=> bootm $loadaddr - $oftaddr 3739## Booting image at 00200000 ... 3740 Image Name: Linux-2.6.17-dirty 3741 Image Type: PowerPC Linux Kernel Image (gzip compressed) 3742 Data Size: 1029343 Bytes = 1005.2 kB 3743 Load Address: 00000000 3744 Entry Point: 00000000 3745 Verifying Checksum ... OK 3746 Uncompressing Kernel Image ... OK 3747Booting using flat device tree at 0x300000 3748Using MPC85xx ADS machine description 3749Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb 3750[snip] 3751 3752 3753More About U-Boot Image Types: 3754------------------------------ 3755 3756U-Boot supports the following image types: 3757 3758 "Standalone Programs" are directly runnable in the environment 3759 provided by U-Boot; it is expected that (if they behave 3760 well) you can continue to work in U-Boot after return from 3761 the Standalone Program. 3762 "OS Kernel Images" are usually images of some Embedded OS which 3763 will take over control completely. Usually these programs 3764 will install their own set of exception handlers, device 3765 drivers, set up the MMU, etc. - this means, that you cannot 3766 expect to re-enter U-Boot except by resetting the CPU. 3767 "RAMDisk Images" are more or less just data blocks, and their 3768 parameters (address, size) are passed to an OS kernel that is 3769 being started. 3770 "Multi-File Images" contain several images, typically an OS 3771 (Linux) kernel image and one or more data images like 3772 RAMDisks. This construct is useful for instance when you want 3773 to boot over the network using BOOTP etc., where the boot 3774 server provides just a single image file, but you want to get 3775 for instance an OS kernel and a RAMDisk image. 3776 3777 "Multi-File Images" start with a list of image sizes, each 3778 image size (in bytes) specified by an "uint32_t" in network 3779 byte order. This list is terminated by an "(uint32_t)0". 3780 Immediately after the terminating 0 follow the images, one by 3781 one, all aligned on "uint32_t" boundaries (size rounded up to 3782 a multiple of 4 bytes). 3783 3784 "Firmware Images" are binary images containing firmware (like 3785 U-Boot or FPGA images) which usually will be programmed to 3786 flash memory. 3787 3788 "Script files" are command sequences that will be executed by 3789 U-Boot's command interpreter; this feature is especially 3790 useful when you configure U-Boot to use a real shell (hush) 3791 as command interpreter. 3792 3793Booting the Linux zImage: 3794------------------------- 3795 3796On some platforms, it's possible to boot Linux zImage. This is done 3797using the "bootz" command. The syntax of "bootz" command is the same 3798as the syntax of "bootm" command. 3799 3800Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply 3801kernel with raw initrd images. The syntax is slightly different, the 3802address of the initrd must be augmented by it's size, in the following 3803format: "<initrd addres>:<initrd size>". 3804 3805 3806Standalone HOWTO: 3807================= 3808 3809One of the features of U-Boot is that you can dynamically load and 3810run "standalone" applications, which can use some resources of 3811U-Boot like console I/O functions or interrupt services. 3812 3813Two simple examples are included with the sources: 3814 3815"Hello World" Demo: 3816------------------- 3817 3818'examples/hello_world.c' contains a small "Hello World" Demo 3819application; it is automatically compiled when you build U-Boot. 3820It's configured to run at address 0x00040004, so you can play with it 3821like that: 3822 3823 => loads 3824 ## Ready for S-Record download ... 3825 ~>examples/hello_world.srec 3826 1 2 3 4 5 6 7 8 9 10 11 ... 3827 [file transfer complete] 3828 [connected] 3829 ## Start Addr = 0x00040004 3830 3831 => go 40004 Hello World! This is a test. 3832 ## Starting application at 0x00040004 ... 3833 Hello World 3834 argc = 7 3835 argv[0] = "40004" 3836 argv[1] = "Hello" 3837 argv[2] = "World!" 3838 argv[3] = "This" 3839 argv[4] = "is" 3840 argv[5] = "a" 3841 argv[6] = "test." 3842 argv[7] = "<NULL>" 3843 Hit any key to exit ... 3844 3845 ## Application terminated, rc = 0x0 3846 3847Another example, which demonstrates how to register a CPM interrupt 3848handler with the U-Boot code, can be found in 'examples/timer.c'. 3849Here, a CPM timer is set up to generate an interrupt every second. 3850The interrupt service routine is trivial, just printing a '.' 3851character, but this is just a demo program. The application can be 3852controlled by the following keys: 3853 3854 ? - print current values og the CPM Timer registers 3855 b - enable interrupts and start timer 3856 e - stop timer and disable interrupts 3857 q - quit application 3858 3859 => loads 3860 ## Ready for S-Record download ... 3861 ~>examples/timer.srec 3862 1 2 3 4 5 6 7 8 9 10 11 ... 3863 [file transfer complete] 3864 [connected] 3865 ## Start Addr = 0x00040004 3866 3867 => go 40004 3868 ## Starting application at 0x00040004 ... 3869 TIMERS=0xfff00980 3870 Using timer 1 3871 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0 3872 3873Hit 'b': 3874 [q, b, e, ?] Set interval 1000000 us 3875 Enabling timer 3876Hit '?': 3877 [q, b, e, ?] ........ 3878 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0 3879Hit '?': 3880 [q, b, e, ?] . 3881 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0 3882Hit '?': 3883 [q, b, e, ?] . 3884 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0 3885Hit '?': 3886 [q, b, e, ?] . 3887 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0 3888Hit 'e': 3889 [q, b, e, ?] ...Stopping timer 3890Hit 'q': 3891 [q, b, e, ?] ## Application terminated, rc = 0x0 3892 3893 3894Minicom warning: 3895================ 3896 3897Over time, many people have reported problems when trying to use the 3898"minicom" terminal emulation program for serial download. I (wd) 3899consider minicom to be broken, and recommend not to use it. Under 3900Unix, I recommend to use C-Kermit for general purpose use (and 3901especially for kermit binary protocol download ("loadb" command), and 3902use "cu" for S-Record download ("loads" command). See 3903https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3. 3904for help with kermit. 3905 3906 3907Nevertheless, if you absolutely want to use it try adding this 3908configuration to your "File transfer protocols" section: 3909 3910 Name Program Name U/D FullScr IO-Red. Multi 3911 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N 3912 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N 3913 3914 3915NetBSD Notes: 3916============= 3917 3918Starting at version 0.9.2, U-Boot supports NetBSD both as host 3919(build U-Boot) and target system (boots NetBSD/mpc8xx). 3920 3921Building requires a cross environment; it is known to work on 3922NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also 3923need gmake since the Makefiles are not compatible with BSD make). 3924Note that the cross-powerpc package does not install include files; 3925attempting to build U-Boot will fail because <machine/ansi.h> is 3926missing. This file has to be installed and patched manually: 3927 3928 # cd /usr/pkg/cross/powerpc-netbsd/include 3929 # mkdir powerpc 3930 # ln -s powerpc machine 3931 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h 3932 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST 3933 3934Native builds *don't* work due to incompatibilities between native 3935and U-Boot include files. 3936 3937Booting assumes that (the first part of) the image booted is a 3938stage-2 loader which in turn loads and then invokes the kernel 3939proper. Loader sources will eventually appear in the NetBSD source 3940tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the 3941meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz 3942 3943 3944Implementation Internals: 3945========================= 3946 3947The following is not intended to be a complete description of every 3948implementation detail. However, it should help to understand the 3949inner workings of U-Boot and make it easier to port it to custom 3950hardware. 3951 3952 3953Initial Stack, Global Data: 3954--------------------------- 3955 3956The implementation of U-Boot is complicated by the fact that U-Boot 3957starts running out of ROM (flash memory), usually without access to 3958system RAM (because the memory controller is not initialized yet). 3959This means that we don't have writable Data or BSS segments, and BSS 3960is not initialized as zero. To be able to get a C environment working 3961at all, we have to allocate at least a minimal stack. Implementation 3962options for this are defined and restricted by the CPU used: Some CPU 3963models provide on-chip memory (like the IMMR area on MPC8xx and 3964MPC826x processors), on others (parts of) the data cache can be 3965locked as (mis-) used as memory, etc. 3966 3967 Chris Hallinan posted a good summary of these issues to the 3968 U-Boot mailing list: 3969 3970 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)? 3971 From: "Chris Hallinan" <clh@net1plus.com> 3972 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET) 3973 ... 3974 3975 Correct me if I'm wrong, folks, but the way I understand it 3976 is this: Using DCACHE as initial RAM for Stack, etc, does not 3977 require any physical RAM backing up the cache. The cleverness 3978 is that the cache is being used as a temporary supply of 3979 necessary storage before the SDRAM controller is setup. It's 3980 beyond the scope of this list to explain the details, but you 3981 can see how this works by studying the cache architecture and 3982 operation in the architecture and processor-specific manuals. 3983 3984 OCM is On Chip Memory, which I believe the 405GP has 4K. It 3985 is another option for the system designer to use as an 3986 initial stack/RAM area prior to SDRAM being available. Either 3987 option should work for you. Using CS 4 should be fine if your 3988 board designers haven't used it for something that would 3989 cause you grief during the initial boot! It is frequently not 3990 used. 3991 3992 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere 3993 with your processor/board/system design. The default value 3994 you will find in any recent u-boot distribution in 3995 walnut.h should work for you. I'd set it to a value larger 3996 than your SDRAM module. If you have a 64MB SDRAM module, set 3997 it above 400_0000. Just make sure your board has no resources 3998 that are supposed to respond to that address! That code in 3999 start.S has been around a while and should work as is when 4000 you get the config right.
4001 4002 -Chris Hallinan 4003 DS4.COM, Inc. 4004 4005It is essential to remember this, since it has some impact on the C 4006code for the initialization procedures: 4007 4008* Initialized global data (data segment) is read-only. Do not attempt 4009 to write it. 4010 4011* Do not use any uninitialized global data (or implicitly initialized 4012 as zero data - BSS segment) at all - this is undefined, initiali- 4013 zation is performed later (when relocating to RAM). 4014 4015* Stack space is very limited. Avoid big data buffers or things like 4016 that. 4017 4018Having only the stack as writable memory limits means we cannot use 4019normal global data to share information between the code. But it 4020turned out that the implementation of U-Boot can be greatly 4021simplified by making a global data structure (gd_t) available to all 4022functions. We could pass a pointer to this data as argument to _all_ 4023functions, but this would bloat the code. Instead we use a feature of 4024the GCC compiler (Global Register Variables) to share the data: we 4025place a pointer (gd) to the global data into a register which we 4026reserve for this purpose. 4027 4028When choosing a register for such a purpose we are restricted by the 4029relevant (E)ABI specifications for the current architecture, and by 4030GCC's implementation. 4031 4032For PowerPC, the following registers have specific use: 4033 R1: stack pointer 4034 R2: reserved for system use 4035 R3-R4: parameter passing and return values 4036 R5-R10: parameter passing 4037 R13: small data area pointer 4038 R30: GOT pointer 4039 R31: frame pointer 4040 4041 (U-Boot also uses R12 as internal GOT pointer. r12 4042 is a volatile register so r12 needs to be reset when 4043 going back and forth between asm and C) 4044 4045 ==> U-Boot will use R2 to hold a pointer to the global data 4046 4047 Note: on PPC, we could use a static initializer (since the 4048 address of the global data structure is known at compile time), 4049 but it turned out that reserving a register results in somewhat 4050 smaller code - although the code savings are not that big (on 4051 average for all boards 752 bytes for the whole U-Boot image, 4052 624 text + 127 data). 4053 4054On ARM, the following registers are used: 4055 4056 R0: function argument word/integer result 4057 R1-R3: function argument word 4058 R9: platform specific 4059 R10: stack limit (used only if stack checking is enabled) 4060 R11: argument (frame) pointer 4061 R12: temporary workspace 4062 R13: stack pointer 4063 R14: link register 4064 R15: program counter 4065 4066 ==> U-Boot will use R9 to hold a pointer to the global data 4067 4068 Note: on ARM, only R_ARM_RELATIVE relocations are supported. 4069 4070On Nios II, the ABI is documented here: 4071 https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf 4072 4073 ==> U-Boot will use gp to hold a pointer to the global data 4074 4075 Note: on Nios II, we give "-G0" option to gcc and don't use gp 4076 to access small data sections, so gp is free. 4077 4078On NDS32, the following registers are used: 4079 4080 R0-R1: argument/return 4081 R2-R5: argument 4082 R15: temporary register for assembler 4083 R16: trampoline register 4084 R28: frame pointer (FP) 4085 R29: global pointer (GP) 4086 R30: link register (LP) 4087 R31: stack pointer (SP) 4088 PC: program counter (PC) 4089 4090 ==> U-Boot will use R10 to hold a pointer to the global data 4091 4092NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope, 4093or current versions of GCC may "optimize" the code too much. 4094 4095On RISC-V, the following registers are used: 4096 4097 x0: hard-wired zero (zero) 4098 x1: return address (ra) 4099 x2: stack pointer (sp) 4100 x3: global pointer (gp) 4101 x4: thread pointer (tp) 4102 x5: link register (t0) 4103 x8: frame pointer (fp) 4104 x10-x11: arguments/return values (a0-1) 4105 x12-x17: arguments (a2-7) 4106 x28-31: temporaries (t3-6) 4107 pc: program counter (pc) 4108 4109 ==> U-Boot will use gp to hold a pointer to the global data 4110 4111Memory Management: 4112------------------ 4113 4114U-Boot runs in system state and uses physical addresses, i.e. the 4115MMU is not used either for address mapping nor for memory protection. 4116 4117The available memory is mapped to fixed addresses using the memory 4118controller. In this process, a contiguous block is formed for each 4119memory type (Flash, SDRAM, SRAM), even when it consists of several 4120physical memory banks. 4121 4122U-Boot is installed in the first 128 kB of the first Flash bank (on 4123TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After 4124booting and sizing and initializing DRAM, the code relocates itself 4125to the upper end of DRAM. Immediately below the U-Boot code some 4126memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN 4127configuration setting]. Below that, a structure with global Board 4128Info data is placed, followed by the stack (growing downward). 4129 4130Additionally, some exception handler code is copied to the low 8 kB 4131of DRAM (0x00000000 ... 0x00001FFF). 4132 4133So a typical memory configuration with 16 MB of DRAM could look like 4134this: 4135 4136 0x0000 0000 Exception Vector code 4137 : 4138 0x0000 1FFF 4139 0x0000 2000 Free for Application Use 4140 : 4141 : 4142 4143 : 4144 : 4145 0x00FB FF20 Monitor Stack (Growing downward) 4146 0x00FB FFAC Board Info Data and permanent copy of global data 4147 0x00FC 0000 Malloc Arena 4148 : 4149 0x00FD FFFF 4150 0x00FE 0000 RAM Copy of Monitor Code 4151 ... eventually: LCD or video framebuffer 4152 ... eventually: pRAM (Protected RAM - unchanged by reset) 4153 0x00FF FFFF [End of RAM] 4154 4155 4156System Initialization: 4157---------------------- 4158 4159In the reset configuration, U-Boot starts at the reset entry point 4160(on most PowerPC systems at address 0x00000100). Because of the reset 4161configuration for CS0# this is a mirror of the on board Flash memory. 4162To be able to re-map memory U-Boot then jumps to its link address. 4163To be able to implement the initialization code in C, a (small!) 4164initial stack is set up in the internal Dual Ported RAM (in case CPUs 4165which provide such a feature like), or in a locked part of the data 4166cache. After that, U-Boot initializes the CPU core, the caches and 4167the SIU. 4168 4169Next, all (potentially) available memory banks are mapped using a 4170preliminary mapping. For example, we put them on 512 MB boundaries 4171(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash 4172on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is 4173programmed for SDRAM access. Using the temporary configuration, a 4174simple memory test is run that determines the size of the SDRAM 4175banks. 4176 4177When there is more than one SDRAM bank, and the banks are of 4178different size, the largest is mapped first. For equal size, the first 4179bank (CS2#) is mapped first. The first mapping is always for address 41800x00000000, with any additional banks following immediately to create 4181contiguous memory starting from 0. 4182 4183Then, the monitor installs itself at the upper end of the SDRAM area 4184and allocates memory for use by malloc() and for the global Board 4185Info data; also, the exception vector code is copied to the low RAM 4186pages, and the final stack is set up. 4187 4188Only after this relocation will you have a "normal" C environment; 4189until that you are restricted in several ways, mostly because you are 4190running from ROM, and because the code will have to be relocated to a 4191new address in RAM. 4192 4193 4194U-Boot Porting Guide: 4195---------------------- 4196 4197[Based on messages by Jerry Van Baren in the U-Boot-Users mailing 4198list, October 2002] 4199 4200 4201int main(int argc, char *argv[]) 4202{ 4203 sighandler_t no_more_time; 4204 4205 signal(SIGALRM, no_more_time); 4206 alarm(PROJECT_DEADLINE - toSec (3 * WEEK)); 4207 4208 if (available_money > available_manpower) { 4209 Pay consultant to port U-Boot; 4210 return 0; 4211 } 4212 4213 Download latest U-Boot source; 4214 4215 Subscribe to u-boot mailing list; 4216 4217 if (clueless) 4218 email("Hi, I am new to U-Boot, how do I get started?"); 4219 4220 while (learning) { 4221 Read the README file in the top level directory; 4222 Read https://www.denx.de/wiki/bin/view/DULG/Manual; 4223 Read applicable doc/README.*; 4224 Read the source, Luke; 4225 /* find . -name "*.[chS]" | xargs grep -i <keyword> */ 4226 } 4227 4228 if (available_money > toLocalCurrency ($2500)) 4229 Buy a BDI3000; 4230 else 4231 Add a lot of aggravation and time; 4232 4233 if (a similar board exists) { /* hopefully... */ 4234 cp -a board/<similar> board/<myboard> 4235 cp include/configs/<similar>.h include/configs/<myboard>.h 4236 } else { 4237 Create your own board support subdirectory; 4238 Create your own board include/configs/<myboard>.h file; 4239 } 4240 Edit new board/<myboard> files 4241 Edit new include/configs/<myboard>.h 4242 4243 while (!accepted) { 4244 while (!running) { 4245 do { 4246 Add / modify source code; 4247 } until (compiles); 4248 Debug; 4249 if (clueless) 4250 email("Hi, I am having problems..."); 4251 } 4252 Send patch file to the U-Boot email list; 4253 if (reasonable critiques) 4254 Incorporate improvements from email list code review; 4255 else 4256 Defend code as written; 4257 } 4258 4259 return 0; 4260} 4261 4262void no_more_time (int sig) 4263{ 4264 hire_a_guru(); 4265} 4266 4267 4268Coding Standards: 4269----------------- 4270 4271All contributions to U-Boot should conform to the Linux kernel 4272coding style; see the kernel coding style guide at 4273https://www.kernel.org/doc/html/latest/process/coding-style.html, and the 4274script "scripts/Lindent" in your Linux kernel source directory. 4275 4276Source files originating from a different project (for example the 4277MTD subsystem) are generally exempt from these guidelines and are not 4278reformatted to ease subsequent migration to newer versions of those 4279sources. 4280 4281Please note that U-Boot is implemented in C (and to some small parts in 4282Assembler); no C++ is used, so please do not use C++ style comments (//) 4283in your code. 4284 4285Please also stick to the following formatting rules: 4286- remove any trailing white space 4287- use TAB characters for indentation and vertical alignment, not spaces 4288- make sure NOT to use DOS '\r\n' line feeds 4289- do not add more than 2 consecutive empty lines to source files 4290- do not add trailing empty lines to source files 4291 4292Submissions which do not conform to the standards may be returned 4293with a request to reformat the changes. 4294 4295 4296Submitting Patches: 4297------------------- 4298 4299Since the number of patches for U-Boot is growing, we need to 4300establish some rules. Submissions which do not conform to these rules 4301may be rejected, even when they contain important and valuable stuff. 4302 4303Please see https://www.denx.de/wiki/U-Boot/Patches for details. 4304 4305Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>; 4306see https://lists.denx.de/listinfo/u-boot 4307 4308When you send a patch, please include the following information with 4309it: 4310 4311* For bug fixes: a description of the bug and how your patch fixes 4312 this bug. Please try to include a way of demonstrating that the 4313 patch actually fixes something. 4314 4315* For new features: a description of the feature and your 4316 implementation. 4317 4318* For major contributions, add a MAINTAINERS file with your 4319 information and associated file and directory references. 4320 4321* When you add support for a new board, don't forget to add a 4322 maintainer e-mail address to the boards.cfg file, too. 4323 4324* If your patch adds new configuration options, don't forget to 4325 document these in the README file. 4326 4327* The patch itself. If you are using git (which is *strongly* 4328 recommended) you can easily generate the patch using the 4329 "git format-patch". If you then use "git send-email" to send it to 4330 the U-Boot mailing list, you will avoid most of the common problems 4331 with some other mail clients. 4332 4333 If you cannot use git, use "diff -purN OLD NEW". If your version of 4334 diff does not support these options, then get the latest version of 4335 GNU diff. 4336 4337 The current directory when running this command shall be the parent 4338 directory of the U-Boot source tree (i. e. please make sure that 4339 your patch includes sufficient directory information for the 4340 affected files). 4341 4342 We prefer patches as plain text. MIME attachments are discouraged, 4343 and compressed attachments must not be used. 4344 4345* If one logical set of modifications affects or creates several 4346 files, all these changes shall be submitted in a SINGLE patch file. 4347 4348* Changesets that contain different, unrelated modifications shall be 4349 submitted as SEPARATE patches, one patch per changeset. 4350 4351 4352Notes: 4353 4354* Before sending the patch, run the buildman script on your patched 4355 source tree and make sure that no errors or warnings are reported 4356 for any of the boards. 4357 4358* Keep your modifications to the necessary minimum: A patch 4359 containing several unrelated changes or arbitrary reformats will be 4360 returned with a request to re-formatting / split it. 4361 4362* If you modify existing code, make sure that your new code does not 4363 add to the memory footprint of the code ;-) Small is beautiful! 4364 When adding new features, these should compile conditionally only 4365 (using #ifdef), and the resulting code with the new feature 4366 disabled must not need more memory than the old code without your 4367 modification. 4368 4369* Remember that there is a size limit of 100 kB per message on the 4370 u-boot mailing list. Bigger patches will be moderated. If they are 4371 reasonable and not too big, they will be acknowledged. But patches 4372 bigger than the size limit should be avoided. 4373