vb2: Modify phase2 behavior for S3 resume case
If a platform does verification of memory init then it must be careful
to use the same slot for resume that it booted from. This is
accomplished by adding a context flag to indicate this is an S3 resume
and that vboot should treat it differently than a normal boot.
When this flag is set then the same slot that was booted is read from
VBNV and re-used for the resume path, without adjusting any try flags.
If this slot is B then the related context flag is set.
This will allow the firmware updater to update the other (non-booted)
slot and set flags indicating that on the next boot the updated slot
should be tried, while still allowing suspend/resume to work with the
existing firmware slot.
This assumes that the last tried slot was successfully booted, which
should be a safe assumption since the system was able to boot and then
suspend. It isn't reliable to check last_fw_result for "success"
status because that status is only set some time after boot when
chromeos-setgoodkernel calls chromeos-firmwareupdate --mode=bootok
and so it may still report a status of "trying" on resume depending
on how soon after boot the suspend happened.
It also avoids setting the vboot flag indicating that a slot choice
was made in order to avoid altering the try counter on failure since
this is explicitly not attempting to boot the new slot.
TEST=manually tested on chell:
1) ensure that booting from slot A resumes from slot A.
2) ensure that booting from slot B resumes from slot B.
3) do RW update while booted from slot A (so the flags are set to try
slot B) and ensure that suspend/resume still functions properly using
current slot A.
4) do RW update while booted from slot B (so the flags are set to try
slot A) and ensure that suspend/resume still functions properly using
current slot B.
Signed-off-by: Duncan Laurie <email@example.com>
Reviewed-by: Aaron Durbin <firstname.lastname@example.org>
2 files changed