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One of our partners was getting confused by the incorrect comments. Daisy, Snow and Pit use STM32xxxx parts with 128KB flash, but the comments indicated that they use 64KB parts. BUG=none BRANCH=none TEST=locally compiled Signed-off-by: David Hendricks <dhendrix@chromium.org> Change-Id: I13035ca9fb0e4cb05f46df250f6b9079a799dd64 Reviewed-on: https://chromium-review.googlesource.com/172663 Reviewed-by: Vincent Palatin <vpalatin@chromium.org> Tested-by: David Hendricks <dhendrix@chromium.org> Reviewed-by: Randall Spangler <rspangler@chromium.org> Commit-Queue: David Hendricks <dhendrix@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.