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How it approximately works:
(During a normal system run):
1. OS puts a capsule into RAM and calls UpdateCapsule() function of EFI
runtime
2. If applying the update requires a reboot, EFI implementation creates
a new CapsuleUpdateData* EFI variable pointing at the beginning of
capsules description (not data, but description of the data) and does
a warm reboot leaving capsule data and its description in RAM to be
picked by firmware on the next boot process
(After DEV_INIT:)
3. Capsules are discovered by checking for CapsuleUpdateData* variables
4. Capsule description in memory and capsule data is validated for
sanity
5. Capsule data is coalesced into a continuous piece of memory
(On BS_WRITE_TABLES via dasharo_add_capsules_to_bootmem() hook:)
6. Buffer with coalesced capsules is marked as reserved
(On BS_WRITE_TABLES via lb_uefi_capsules() hook:)
7. coreboot table entry is added for each of the discovered capsules
(In UEFI payload:)
8. CapsuleUpdateData* get removed
9. coreboot table is checked for any update capsules which are then
applied
Change-Id: I162d678ae5c504906084b59c1a8d8c26dadb9433
Signed-off-by: Sergii Dmytruk <sergii.dmytruk@3mdeb.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/83422
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Krystian Hebel <krystian.hebel@3mdeb.com>
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