arm: init: save previous bootloader data
When u-boot is used as a chain-loaded bootloader (replacing OS kernel),
previous bootloader leaves data in RAM, that can be reused.
For example, on recent arm linux system, when chainloading u-boot,
there are initramfs and fdt in RAM prepared for OS booting. Initramfs
may be modified to store u-boot's payload, thus providing the ability to
use chainloaded u-boot to boot OS without any storage support.
Two config options added:
- SAVE_PREV_BL_INITRAMFS_START_ADDR
saves initramfs start address to 'prevbl_initrd_start_addr' environment
variable
- SAVE_PREV_BL_FDT_ADDR
saves fdt address to 'prevbl_fdt_addr' environment variable
Signed-off-by: Dzmitry Sankouski <dsankouski@gmail.com>
Cc: Tom Rini <trini@konsulko.com>
diff --git a/boot/Kconfig b/boot/Kconfig
index 394b26f..ec5b956 100644
--- a/boot/Kconfig
+++ b/boot/Kconfig
@@ -1192,4 +1192,28 @@
help
This option is used to set the default fdt file to boot OS.
+config SAVE_PREV_BL_FDT_ADDR
+ depends on ARM
+ bool "Saves fdt address, passed by the previous bootloader, to env var"
+ help
+ When u-boot is used as a chain-loaded bootloader (replacing OS kernel),
+ enable this option to save fdt address, passed by the
+ previous bootloader for future use.
+ Address is saved to `prevbl_fdt_addr` environment variable.
+
+ If no fdt was provided by previous bootloader, no env variables
+ will be created.
+
+config SAVE_PREV_BL_INITRAMFS_START_ADDR
+ depends on ARM
+ bool "Saves initramfs address, passed by the previous bootloader, to env var"
+ help
+ When u-boot is used as a chain-loaded bootloader(replacing OS kernel),
+ enable this option to save initramfs address, passed by the
+ previous bootloader for future use.
+ Address is saved to `prevbl_initrd_start_addr` environment variable.
+
+ If no initramfs was provided by previous bootloader, no env variables
+ will be created.
+
endmenu # Booting