On 24 August 2017 at 13:02, Leif Lindholm <[email protected]> wrote: > On Wed, Aug 23, 2017 at 04:00:57PM +0100, Leif Lindholm wrote: >> On Wed, Aug 23, 2017 at 03:36:37PM +0200, Laszlo Ersek wrote: >> > On 08/23/17 15:17, Ard Biesheuvel wrote: >> > >>>> (My R-b stands; these are comments for a possible followup patch.) >> > >>>> >> > >>>> Please see: >> > >>>> >> > >>>> - commit 84a75f70e903 ("OvmfPkg/QemuVideoDxe: enable ARM builds", >> > >>>> 2015-02-23), >> > >>>> >> > >>>> - commit 05a537945872 ("OvmfPkg/QemuVideoDxe: Helper functions for >> > >>>> unaligned port I/O.", 2017-04-07)? >> > >>>> >> > >>>> In my opinion, we should now revert parts of these commits, in one >> > >>>> followup patch: >> > >>>> >> > >>>> - from the first commit, we should revert only the >> > >>>> "VALID_ARCHITECTURES" >> > >>>> comment change (the rest is built upon by the second commit, and >> > >>>> should >> > >>>> be preserved) >> > >>>> >> > >>>> - from the second commit, we should revert the addition of >> > >>>> [Sources.ARM, >> > >>>> Sources.AARCH64]. >> > >>>> >> > >>>> This boils down to removing ARM and AARCH64 references from the >> > >>>> QemuVideoDxe.inf file. If you agree, could you please submit such a >> > >>>> followup patch? >> > >>> >> > >>> Sure, but pending the graphical GRUB discussion. >> > >> >> > >> So, after looking at the GRUB code, I am leaning towards agreeing that >> > >> this is actually not a problem at all ... probably. The efi_gop driver >> > >> does a Blt() of the entire screen from an off-screen buffer for all >> > >> updates _unless_ it fails to allocate that off-screen buffer. >> > >> >> > >> So, basically, if you run out of memory at that point, it will try to >> > >> preserve a way to get messages out about that. I will send a question >> > >> out to grub-devel regarding this behaviour. >> > >> >> > >> However, looking at the specification, a question remains over how >> > >> software can determine whether direct FB access is possible. I mean, a >> > >> value of 0 seems like a decent hint, but the spec says nothing on the >> > >> topic. >> > >> >> > > >> > > It will assume the FB is accessible unless the pixel format is >> > > PixelBltOnly >> > > >> > >> > Correct, the UEFI spec (v2.7) says in "12.9 Graphics Output Protocol": >> > >> > PixelBltOnly This mode does not support a physical frame buffer. >> > >> > and >> > >> > PixelFormat Enumeration that defines the physical format of the >> > pixel. A value of PixelBltOnly implies that a linear >> > frame buffer is not available for this mode. >> >> -ETOOMANYLEVELSOFINDIRECTION >> Right, so that's a non-issue. >> >> Hopefully, that means other operating systems can also deal with the >> lack. >> >> > IIRC simply recognizing and accepting this enum constant was the point >> > of Alex's patch. >> >> Ah, yes, that makes sense now. >> It's a bit surprising things work without this patch, but GRUBs >> fallback seems to match anyway. > > To clarify: > Reviewed-by: Leif Lindholm <[email protected]>
Pushed, thanks. _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
