Re: [PATCH 0/5] gfx: improvements when using multiboot2 and EFI + misc

["Roger Pau Monné" <roger.pau@citrix.com>]

On Thu, Nov 24, 2022 at 06:15:15AM +0100, Marek Marczykowski-Górecki wrote:
> On Wed, Nov 23, 2022 at 04:45:19PM +0100, Roger Pau Monne wrote:
> > Marek: after this series using console= without the vga option should
> > result in Xen not attempting to touch the selected GOP mode and the
> > screen not getting cleared.
> 
> Thanks, this seems to work mostly fine.
> There is one message printed from setup_efi_pci(): ... ROM ... bytes at ...
> I'm not sure what to do about this one (although for Qubes, I can simply
> patch it out ;) ).

Hm, I'm unsure.  As a starter they could be gated to debug hypervisor only
builds.  And then I'm unsure whether this information couldn't be
printed later when the console option has been parsed, instead of
printing it from the EFI console interface.

> But to get dom0 display image from BGRT, it seems something else is
> needed too. Linux complains "Incorrect checksum in table [BGRT]". The
> only relevant google result I get is this: https://support.citrix.com/article/CTX460227/citrix-hypervisor-acpi-warning-incorrect-checksum-in-table-bgrt
> It blames firmware. But then, it's suspicious that it's also about Xen.
> And also, native Linux on the same hw does not complain about the
> checksum. So, I think it's rather Xen to blame...
> The table lives in area marked as EfiACPIReclaimMemory in memory map, so
> I think it shouldn't be clobbered by Xen, at least in theory. I'll look
> into it later. It's getting off-topic for this thread anyway.

See commit 89238ef7797023f318f82f4f9dddef59c435b8bd.  I wonder whether
the BGRT image region is marked as EFI_MEMORY_RUNTIME, I will have to
check on my system.

Thanks, Roger.