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Previously I neglected to increment the buffer pointer which would allow double writing of same data and exclude tail if write didn't complete in one call. Also fixing bug with EAGAIN/EWOULDBLOCK to retry in those cases. Previously we'd just have just failed for those errno values. Signed-off-by: Todd Broch <tbroch@chromium.org> BRANCH=none BUG=chromium:371147 TEST=still compiles Change-Id: I30dbe56b2a4c735c487464349786a9db430130a8 Reviewed-on: https://chromium-review.googlesource.com/199052 Reviewed-by: Vincent Palatin <vpalatin@chromium.org> Commit-Queue: Todd Broch <tbroch@chromium.org> Tested-by: Todd Broch <tbroch@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.