vboot: boot from miniOS recovery kernels on disk

Add VbTryLoadMiniOsKernel() to vboot API, which boots from a miniOS
recovery kernel located on internal disk. In this boot path, an attempt
is made to verify and boot this kernel. Recovery proceeds from within
the miniOS kernel by downloading a recovery image over the network. No
USB disk is used in the process.

For more information, see go/nbr-firmware.

BUG=b:188121855, b:186682292
TEST=make clean && make runtests

Change-Id: Ic4d1fe5642a2bf71c51c78fd7830ad2b6e9eebeb
Signed-off-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2856364
Reviewed-by: Julius Werner <jwerner@chromium.org>
9 files changed