diff options
Diffstat (limited to 'README')
| -rw-r--r-- | README | 96 |
1 files changed, 91 insertions, 5 deletions
@@ -273,6 +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: ---------------------- @@ -741,7 +810,6 @@ The following options need to be configured: Enable removing of devices. - - Linux Kernel Interface: CONFIG_CLOCKS_IN_MHZ @@ -3159,8 +3227,18 @@ 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'. @@ -3454,8 +3532,10 @@ 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 @@ -4348,6 +4428,9 @@ 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 @@ -4923,6 +5006,9 @@ 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. |