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Move the CLZ instruction emulation C code to the common directory, so it can be reused for all CPU cores missing a CLZ instruction (e.g. CortexM0). Signed-off-by: Vincent Palatin <vpalatin@chromium.org> BRANCH=none BUG=none TEST=run EC console on STM32F072B Discovery board with Cortex-M0 core, and pass all available unit-tests on target. Change-Id: Ief56cac7430fcb0fbced8a8925250c89cbd0bcfc Reviewed-on: https://chromium-review.googlesource.com/188981 Reviewed-by: Alec Berg <alecaberg@chromium.org> Reviewed-by: Randall Spangler <rspangler@chromium.org> Commit-Queue: Vincent Palatin <vpalatin@chromium.org> Tested-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.