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The EFI Graphics Output Protocol uses 64-bit frame buffer addresses but these get truncated to 32-bit by the EFI boot stub when storing the address in the 'lfb_base' field of 'struct screen_info'. Add a 'ext_lfb_base' field for the upper 32-bits of the frame buffer address and set VIDEO_TYPE_CAPABILITY_64BIT_BASE when the field is useable. It turns out that the reason no one has required this support so far is that there's actually code in tianocore to "downgrade" PCI resources that have option ROMs and 64-bit BARS from 64-bit to 32-bit to cope with legacy option ROMs that can't handle 64-bit addresses. The upshot is that basically all GOP devices in the wild use a 32-bit frame buffer address. Still, it is possible to build firmware that uses a full 64-bit GOP frame buffer address. Chad did, which led to him reporting this issue. Add support in anticipation of GOP devices using 64-bit addresses more widely, and so that efifb works out of the box when that happens. Reported-by: Chad Page <chad.page@znyx.com> Cc: Pete Hawkins <pete.hawkins@znyx.com> Acked-by: Peter Jones <pjones@redhat.com> Cc: Matthew Garrett <mjg59@srcf.ucam.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Matt Fleming <matt.fleming@intel.com> |
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