Reuse framebuffer after a kexec (amdgpu / efifb)

[Alex Deucher]

On Fri, Dec 10, 2021 at 9:25 AM Guilherme G. Piccoli
<gpiccoli at igalia.com> wrote:
>
> On 10/12/2021 11:16, Alex Deucher wrote:> [...]
> > Why not just reload the driver after kexec?
> >
> > Alex
>
> Because the original issue is the kdump case, and we want a very very
> tiny kernel - also, the crash originally could have been caused by
> amdgpu itself, so if it's a GPU issue, we don't want to mess with that
> in kdump. And I confess I tried modprobe amdgpu after a kdump, no
> success - kdump won't call shutdown handlers, so GPU will be in a
> "rogue" state...
>
> My question was about regular kexec because it's much simpler usually,
> we can do whatever we want there. My line of thought was: if I make it
> work in regular kexec with a simple framebuffer, I might be able to get
> it working on kdump heheh
>

Well if the GPU is hung, I'm not sure if you'll be able to get back
the display environment without a GPU reset and once you do that,
you've lost any state you might have been trying to preserve.

Alex