Re: [Xen-devel] [PATCH 2/2] efi/boot: make sure chosen mode is set even if firmware tell it is

[Jan Beulich <jbeulich@xxxxxxxx>]

On 04.10.2019 13:33, Igor Druzhinin wrote:
> On 04/10/2019 11:40, Jan Beulich wrote:
>> On 03.10.2019 15:49, Igor Druzhinin wrote:
>>> If a bootloader is using native driver instead of EFI GOP it might
>>> reset graphics mode to be different from what firmware thinks it
>>> currently is. Set chosen mode unconditionally to fix this possible
>>> misalignment.
>>>
>>> Observed with EFI GRUB2 compiled with all possible video drivers where
>>> native drivers take priority over firmware.
>>
>> I don't think this case can happen with just plain EFI. Therefore ...
>>
> 
> Could you clarify what you mean by "plain EFI" here? Do you mean being
> booted as EFI binary unlike through multiboot protocol?

Yes - like when running xen.efi from the EFI shell command line.

> I think in both
> cases it's possible to come there through a bootloader.

Anything invoking an EFI application with a screwed up EFI
environment is bogus. I can see how grub would violate such
assumptions though, and how one might call this valid when
invoking the next binary with a protocol other than what plain
EFI provides (read: MB2 here).

Jan

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