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In order to achieve really tiny firmwares, make our runtime (tasks, hooks, muxed timers, GPIO abstraction ...) optional. Add 2 new build options for it : CONFIG_COMMON_RUNTIME and CONFIG_COMMON_GPIO which are enabled by default, and ensure all the source files are built according to the right configuration variable. Signed-off-by: Vincent Palatin <vpalatin@chromium.org> BRANCH=none BUG=none TEST=make buildall build a minimal board with no runtime. Change-Id: Icb621cbe0a75b3a320cb53c3267d6e578cd3c32f Reviewed-on: https://chromium-review.googlesource.com/189403 Reviewed-by: Vic Yang <victoryang@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.