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authorGabe Black <gabeblack@google.com>2014-02-08 06:30:49 -0800
committerMarc Jones <marc.jones@se-eng.com>2014-12-09 18:38:48 +0100
commitc09cf0b7e17cc48576d09d3c48df8625ea5c990b (patch)
tree20d5b21ba3b49289591176b216271ca3a714c14b /payloads/libpayload/include
parent018560667a06f17b324e078b7f978d80d8ef65a4 (diff)
libpayload: arm: Pass the coreboot table location to the payload.
To find the coreboot tables, the payload has historically searched for their signature in a predefined region of memory. This is a little clumsy on x86, but it works because you can assume certain regions are RAM. Also, there are areas which are set aside for the firmware by convention. On x86 there's a forwarding entry which goes in one of those fairly small conventional areas and which points to the CBMEM area at the end of memory. On ARM there aren't areas like that, so we've left out the forwarding entry and gone directly to CBMEM. RAM may not start at the beginning of the address space or go to its end, and that means there isn't really anywhere fixed you can put the coreboot tables. That's meant that libpayload has to be configured on a per board basis to know where to look for CBMEM. Now that we have boards that don't have fixed amounts of memory, the location of the end of RAM isn't fixed even on a per board level which means even that workaround will no longer cut it. This change makes coreboot pass the location of the coreboot tables to libpayload using r0, the first argument register. That means we'll be able to find them no matter where CBMEM is, and we can get rid of the per board search ranges. We can extend this mechanism to x86 as well, but there may be more complications and it's less necessary there. It would be a good thing to do eventually though. BUG=None TEST=Built and booted on nyan. Changed the size of memory and saw that the payload could still find the coreboot tables where before it couldn't. Built for pit, snow, and big. BRANCH=None Original-Change-Id: I7218afd999da1662b0db8172fd8125670ceac471 Original-Signed-off-by: Gabe Black <gabeblack@google.com> Original-Reviewed-on: https://chromium-review.googlesource.com/185572 Original-Reviewed-by: Julius Werner <jwerner@chromium.org> Original-Commit-Queue: Gabe Black <gabeblack@chromium.org> Original-Tested-by: Gabe Black <gabeblack@chromium.org> (cherry picked from commit ca88f39c21158b59abe3001f986207a292359cf5) Signed-off-by: Marc Jones <marc.jones@se-eng.com> Change-Id: Iab14e9502b6ce7a55f0a72e190fa582f89f11a1e Reviewed-on: http://review.coreboot.org/7655 Tested-by: build bot (Jenkins) Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net> Reviewed-by: Patrick Georgi <pgeorgi@google.com>
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