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fe0b6c1acd
BRANCH=None
BUG=chromium:292965
TEST=CC="i686-pc-linux-gnu-clang" CXX="i686-pc-linux-gnu-clang++"
emerge-x86-generic chromeos-ec passes.
Signed-off-by: yunlian@chromium.org
Change-Id: I936f5e9b3e6ab5a5c1c2f6b6c41d054d748545e3
Reviewed-on: https://chromium-review.googlesource.com/169633
Reviewed-by: Luis Lozano <llozano@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Commit-Queue: Yunlian Jiang <yunlian@chromium.org>
Tested-by: Yunlian Jiang <yunlian@chromium.org>
In the most general case, the flash layout looks something like this: +---------------------+ | Reserved for EC use | +---------------------+ +---------------------+ | Vblock B | +---------------------+ | RW firmware B | +---------------------+ +---------------------+ | Vblock A | +---------------------+ | RW firmware A | +---------------------+ +---------------------+ | FMAP | +---------------------+ | Public root key | +---------------------+ | Read-only firmware | +---------------------+ BIOS firmware (and kernel) put the vblock info at the start of each image where it's easy to find. The Blizzard EC expects the firmware vector table to come first, so we have to put the vblock at the end. This means we have to know where to look for it, but that's built into the FMAP and the RO firmware anyway, so that's not an issue. The RO firmware doesn't need a vblock of course, but it does need some reserved space for vboot-related things. Using SHA256/RSA4096, the vblock is 2468 bytes (0x9a4), while the public root key is 1064 bytes (0x428) and the current FMAP is 644 bytes (0x284). If we reserve 4K at the top of each FW image, that should give us plenty of room for vboot-related stuff.