diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/develop/spl.rst | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/doc/develop/spl.rst b/doc/develop/spl.rst index 76e87f0..0a3e572 100644 --- a/doc/develop/spl.rst +++ b/doc/develop/spl.rst @@ -65,6 +65,15 @@ CONFIG_SPL_NAND_LOAD (drivers/mtd/nand/raw/nand_spl_load.o) CONFIG_SPL_SPI_LOAD (drivers/mtd/spi/spi_spl_load.o) CONFIG_SPL_RAM_DEVICE (common/spl/spl.c) CONFIG_SPL_WATCHDOG (drivers/watchdog/libwatchdog.o) +CONFIG_SPL_SYSCON (drivers/core/syscon-uclass.o) +CONFIG_SPL_GZIP (lib/gzip.o) +CONFIG_SPL_VIDEO (drivers/video/video-uclass.o drivers/video/vidconsole-uclass.o) +CONFIG_SPL_SPLASH_SCREEN (common/splash.o) +CONFIG_SPL_SPLASH_SOURCE (common/splash_source.o) +CONFIG_SPL_GPIO (drivers/gpio) +CONFIG_SPL_DM_GPIO (drivers/gpio/gpio-uclass.o) +CONFIG_SPL_BMP (drivers/video/bmp.o) +CONFIG_SPL_BLOBLIST (common/bloblist.o) Adding SPL-specific code ------------------------ @@ -164,3 +173,31 @@ cflow will spit out a number of warnings as it does not parse the config files and picks functions based on #ifdef. Parsing the '.i' files instead introduces another set of headaches. These warnings are not usually important to understanding the flow, however. + + +Reserving memory in SPL +----------------------- + +If memory needs to be reserved in RAM during SPL stage with the requirement that +the SPL reserved memory remains preserved across further boot stages too +then it needs to be reserved mandatorily starting from end of RAM. This is to +ensure that further stages can simply skip this region before carrying out +further reservations or updating the relocation address. + +Also out of these regions which are to be preserved across further stages of +boot, video framebuffer memory region must be reserved first starting from +end of RAM for which helper function spl_reserve_video_from_ram_top is provided +which makes sure that video memory is placed at top of reservation area with +further reservations below it. + +The corresponding information of reservation for those regions can be passed to +further boot stages using a bloblist. For e.g. the information for +framebuffer area reserved by SPL can be passed onto U-boot using +BLOBLISTT_U_BOOT_VIDEO. + +The further boot stages need to parse each of the bloblist passed from SPL stage +starting from video bloblist and skip this whole SPL reserved memory area from +end of RAM as per the bloblists received, before carrying out further +reservations or updating the relocation address. For e.g, U-boot proper uses +function "setup_relocaddr_from_bloblist" to parse the bloblists passed from +previous stage and skip the memory reserved from previous stage accordingly. |