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The auto_power_on is set 1 unexpectedly while EC jumps. This has a side effect that would turn on the AP unexpectedly after "power off". See comment 43 of issue 28249 BUG=chrome-os-partner:28249 BRANCH=tot,nyan TEST=on nyan: > reboot > sysinfo // If EC is in RO, "sysjump RW" > power off // The AP keeps off. Change-Id: I3c06e99383c06af7cd6c17dd65040e20f06d8e73 Signed-off-by: Louis Yung-Chieh Lo <yjlou@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/198941
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.