X-Git-Url: https://git.sur5r.net/?a=blobdiff_plain;f=README;h=57426e55eae5ae16c0581f0ba923cafaa7ad50f7;hb=9b4d65f918dd84a479552b86ef2cde389926738f;hp=0fec497328bd5fd27df28efda7a14d828a106346;hpb=bd5053ffa5b8162257537bdb79ba829372423096;p=u-boot diff --git a/README b/README index 0fec497328..57426e55ea 100644 --- a/README +++ b/README @@ -182,7 +182,6 @@ Directory Hierarchy: /lib Architecture specific library files /powerpc Files generic to PowerPC architecture /cpu CPU specific files - /74xx_7xx Files specific to Freescale MPC74xx and 7xx CPUs /mpc5xx Files specific to Freescale MPC5xx CPUs /mpc5xxx Files specific to Freescale MPC5xxx CPUs /mpc8xx Files specific to Freescale MPC8xx CPUs @@ -274,6 +273,75 @@ run some of U-Boot's tests. See board/sandbox/README.sandbox for more details. +Board Initialisation Flow: +-------------------------- + +This is the intended start-up flow for boards. This should apply for both +SPL and U-Boot proper (i.e. they both follow the same rules). At present SPL +mostly uses a separate code path, but the funtion names and roles of each +function are the same. Some boards or architectures may not conform to this. +At least most ARM boards which use CONFIG_SPL_FRAMEWORK conform to this. + +Execution starts with start.S with three functions called during init after +that. The purpose and limitations of each is described below. + +lowlevel_init(): + - purpose: essential init to permit execution to reach board_init_f() + - no global_data or BSS + - there is no stack (ARMv7 may have one but it will soon be removed) + - must not set up SDRAM or use console + - must only do the bare minimum to allow execution to continue to + board_init_f() + - this is almost never needed + - return normally from this function + +board_init_f(): + - purpose: set up the machine ready for running board_init_r(): + i.e. SDRAM and serial UART + - global_data is available + - stack is in SRAM + - BSS is not available, so you cannot use global/static variables, + only stack variables and global_data + + Non-SPL-specific notes: + - dram_init() is called to set up DRAM. If already done in SPL this + can do nothing + + SPL-specific notes: + - you can override the entire board_init_f() function with your own + version as needed. + - preloader_console_init() can be called here in extremis + - should set up SDRAM, and anything needed to make the UART work + - these is no need to clear BSS, it will be done by crt0.S + - must return normally from this function (don't call board_init_r() + directly) + +Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at +this point the stack and global_data are relocated to below +CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of +memory. + +board_init_r(): + - purpose: main execution, common code + - global_data is available + - SDRAM is available + - BSS is available, all static/global variables can be used + - execution eventually continues to main_loop() + + Non-SPL-specific notes: + - U-Boot is relocated to the top of memory and is now running from + there. + + SPL-specific notes: + - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and + CONFIG_SPL_STACK_R_ADDR points into SDRAM + - preloader_console_init() can be called here - typically this is + done by defining CONFIG_SPL_BOARD_INIT and then supplying a + spl_board_init() function containing this call + - loads U-Boot or (in falcon mode) Linux + + + Configuration Options: ---------------------- @@ -622,6 +690,21 @@ The following options need to be configured: exists, unlike the similar options in the Linux kernel. Do not set these options unless they apply! + NOTE: The following can be machine specific errata. These + do have ability to provide rudimentary version and machine + specific checks, but expect no product checks. + CONFIG_ARM_ERRATA_430973 + CONFIG_ARM_ERRATA_454179 + CONFIG_ARM_ERRATA_621766 + CONFIG_ARM_ERRATA_798870 + +- Tegra SoC options: + CONFIG_TEGRA_SUPPORT_NON_SECURE + + Support executing U-Boot in non-secure (NS) mode. Certain + impossible actions will be skipped if the CPU is in NS mode, + such as ARM architectural timer initialization. + - Driver Model Driver model is a new framework for devices in U-Boot introduced in early 2014. U-Boot is being progressively @@ -735,7 +818,6 @@ The following options need to be configured: Enable removing of devices. - - Linux Kernel Interface: CONFIG_CLOCKS_IN_MHZ @@ -1258,6 +1340,9 @@ The following options need to be configured: SoC, then define this variable and provide board specific code for the "hw_watchdog_reset" function. + CONFIG_AT91_HW_WDT_TIMEOUT + specify the timeout in seconds. default 2 seconds. + - U-Boot Version: CONFIG_VERSION_VARIABLE If this variable is defined, an environment variable @@ -3150,8 +3235,18 @@ CBFS (Coreboot Filesystem) support Enable the hash verify command (hash -v). This adds to code size a little. - CONFIG_SHA1 - support SHA1 hashing - CONFIG_SHA256 - support SHA256 hashing + CONFIG_SHA1 - This option enables support of hashing using SHA1 + algorithm. The hash is calculated in software. + CONFIG_SHA256 - This option enables support of hashing using + SHA256 algorithm. The hash is calculated in software. + CONFIG_SHA_HW_ACCEL - This option enables hardware acceleration + for SHA1/SHA256 hashing. + This affects the 'hash' command and also the + hash_lookup_algo() function. + CONFIG_SHA_PROG_HW_ACCEL - This option enables + hardware-acceleration for SHA1/SHA256 progressive hashing. + Data can be streamed in a block at a time and the hashing + is performed in hardware. Note: There is also a sha1sum command, which should perhaps be deprecated in favour of 'hash sha1'. @@ -3177,8 +3272,13 @@ CBFS (Coreboot Filesystem) support This enables the RSA algorithm used for FIT image verification in U-Boot. See doc/uImage.FIT/signature.txt for more information. + The Modular Exponentiation algorithm in RSA is implemented using + driver model. So CONFIG_DM needs to be enabled by default for this + library to function. + The signing part is build into mkimage regardless of this - option. + option. The software based modular exponentiation is built into + mkimage irrespective of this option. - bootcount support: CONFIG_BOOTCOUNT_LIMIT @@ -3440,8 +3540,10 @@ FIT uImage format: CONFIG_FIT_SIGNATURE This option enables signature verification of FIT uImages, - using a hash signed and verified using RSA. See - doc/uImage.FIT/signature.txt for more details. + using a hash signed and verified using RSA. If + CONFIG_SHA_PROG_HW_ACCEL is defined, i.e support for progressive + hashing is available using hardware, RSA library will use it. + See doc/uImage.FIT/signature.txt for more details. WARNING: When relying on signed FIT images with required signature check the legacy image format is default @@ -4334,6 +4436,9 @@ to save the current settings. If defined, specified the chip address of the EEPROM device. The default address is zero. + - CONFIG_SYS_I2C_EEPROM_BUS: + If defined, specified the i2c bus of the EEPROM device. + - CONFIG_SYS_EEPROM_PAGE_WRITE_BITS: If defined, the number of bits used to address bytes in a single page in the EEPROM device. A 64 byte page, for example @@ -4909,6 +5014,9 @@ Low Level (hardware related) configuration options: - CONFIG_FSL_DDR_INTERACTIVE Enable interactive DDR debugging. See doc/README.fsl-ddr. +- CONFIG_FSL_DDR_SYNC_REFRESH + Enable sync of refresh for multiple controllers. + - CONFIG_SYS_83XX_DDR_USES_CS0 Only for 83xx systems. If specified, then DDR should be configured using CS0 and CS1 instead of CS2 and CS3. @@ -5900,9 +6008,10 @@ option performs the converse operation of the mkimage's second form (the "-d" option). Given an image built by mkimage, the dumpimage extracts a "data file" from the image: - tools/dumpimage -i image -p position data_file - -i ==> extract from the 'image' a specific 'data_file', \ - indexed by 'position' + tools/dumpimage -i image -T type -p position data_file + -i ==> extract from the 'image' a specific 'data_file' + -T ==> set image type to 'type' + -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image' Installing a Linux Image: