mirror of
https://github.com/Telecominfraproject/OpenCellular.git
synced 2025-12-27 18:25:05 +00:00
53d46c5ca1
once firmware branch exists, this commit need go into it and doesn't need to be carried in master forever BRANCH=blaze BUG=chrome-os-partner:27120 TEST=USE="nyan_blaze" emerge-nyan_blaze chromeos-ec;flash nyan board, verify ec is alive and version is reported as blaze Change-Id: I115890a7122440a25c3d1f5e4b94248099a1de99 Signed-off-by: Neil Chen <neilc@nvidia.com> Reviewed-on: https://chromium-review.googlesource.com/190610 Reviewed-by: Katie Roberts-Hoffman <katierh@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.