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This is just an example, demonstrating how a userspace program can access and control the Pixel lighbar. This change reflects the new unprivileged access methods. You can run this program to drive the lightbar without being root. BUG=chromium:239205 BRANCH=none TEST=manual Nothing builds this by default, but you can test it with cd src/platform/ec gcc -static util/lbplay.c then copy a.out to your Pixel and run it (from /tmp, since other directories are mounted noexec). Change-Id: I7c07512087c924d16c1c03df6176fba995fcd4f4 Signed-off-by: Bill Richardson <wfrichar@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/186672 Reviewed-by: Alec Berg <alecaberg@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.