Add documentation for the Intel PCH Top Swap based A/B redundancy
mechanism. Describe the BOOTBLOCK and TOPSWAP bootblock regions,
COREBOOT and COREBOOT_TS CBFS regions, the attempt_slot_b CMOS option
and its application time, and how the active CBFS region is selected
based on the Top Swap state.
This follows the A/B redundancy proposal discussed on the coreboot
mailing list:
https://mail.coreboot.org/archives/list/coreboot@coreboot.org/thread/C6JN2PB7K7D67EG7OIKB6BBERZU5YV35/
Change-Id: I1b88989201e209b2f69964c067c432ff82a0057e
Signed-off-by: Filip Lewiński <filip.lewinski@3mdeb.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/90412
Reviewed-by: Sergii Dmytruk <sergii.dmytruk@3mdeb.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
95461ee3df
