tree d58972054d39b90b0b0a92d5c9b093d0547264a6
parent 3636a9cfc4ba6060d721757e44f76561d1627771
author Dzmitry Sankouski <dsankouski@gmail.com> 1645555792 +0300
committer Tom Rini <trini@konsulko.com> 1649098406 -0400

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>