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143763421c
On early snow boards, WP GPIO is not wired to the EC. Now that we have properly fixed hardware, we should drop workaround for those boards. BUG=chrome-os-partner:23762 TEST=Build all boards BRANCH=None Change-Id: I5dcfaf5497fc36d6b8d7bc5d8975aa18b2d36a1d Signed-off-by: Vic (Chun-Ju) Yang <victoryang@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/181090 Reviewed-by: Yung-chieh Lo <yjlou@chromium.org> Reviewed-by: Randall Spangler <rspangler@chromium.org> Reviewed-by: Vincent Palatin <vpalatin@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.