linux-kernel - Re: [PATCH 00/12] Recover sysfb after DRM probe failure

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Message-ID: <c78e9794-e63f-47f9-a4cb-e3b5625ab828@kernel.org>
Date: Thu, 15 Jan 2026 10:39:56 -0600
From: Mario Limonciello <superm1@...nel.org>
To: Gerd Hoffmann <kraxel@...hat.com>,
 Ville Syrjälä <ville.syrjala@...ux.intel.com>
Cc: Christian König <christian.koenig@....com>,
 Thomas Zimmermann <tzimmermann@...e.de>, Zack Rusin
 <zack.rusin@...adcom.com>, dri-devel@...ts.freedesktop.org,
 Alex Deucher <alexander.deucher@....com>, amd-gfx@...ts.freedesktop.org,
 Ard Biesheuvel <ardb@...nel.org>, Ce Sun <cesun102@....com>,
 Chia-I Wu <olvaffe@...il.com>, Danilo Krummrich <dakr@...nel.org>,
 Dave Airlie <airlied@...hat.com>, Deepak Rawat <drawat.floss@...il.com>,
 Dmitry Osipenko <dmitry.osipenko@...labora.com>,
 Gurchetan Singh <gurchetansingh@...omium.org>,
 Hans de Goede <hansg@...nel.org>, Hawking Zhang <Hawking.Zhang@....com>,
 Helge Deller <deller@....de>, intel-gfx@...ts.freedesktop.org,
 intel-xe@...ts.freedesktop.org, Jani Nikula <jani.nikula@...ux.intel.com>,
 Javier Martinez Canillas <javierm@...hat.com>,
 Jocelyn Falempe <jfalempe@...hat.com>,
 Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
 Lijo Lazar <lijo.lazar@....com>, linux-efi@...r.kernel.org,
 linux-fbdev@...r.kernel.org, linux-hyperv@...r.kernel.org,
 linux-kernel@...r.kernel.org, Lucas De Marchi <lucas.demarchi@...el.com>,
 Lyude Paul <lyude@...hat.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Mario Limonciello <mario.limonciello@....com>,
 Maxime Ripard <mripard@...nel.org>, nouveau@...ts.freedesktop.org,
 Rodrigo Vivi <rodrigo.vivi@...el.com>, Simona Vetter <simona@...ll.ch>,
 spice-devel@...ts.freedesktop.org,
 Thomas Hellström <thomas.hellstrom@...ux.intel.com>,
 Timur Kristóf <timur.kristof@...il.com>,
 Tvrtko Ursulin <tursulin@...ulin.net>, virtualization@...ts.linux.dev,
 Vitaly Prosyak <vitaly.prosyak@....com>
Subject: Re: [PATCH 00/12] Recover sysfb after DRM probe failure

On 1/15/26 10:36 AM, Gerd Hoffmann wrote:
>    Hi,
> 
>>> At least for AMD GPUs remove_conflicting_devices() really early is
>>> necessary because otherwise some operations just result in a
>>> spontaneous system reboot.	
> 
>> It's similar for Intel. For us VGA emulation won't be used for EFI
>> boot, but we still can't have the previous driver poking around in
>> memory while the real driver is initializing. The entire memory layout
>> may get completely shuffled so there's no telling where such memory
>> accesses would land.
> 
> Can you do stuff like checking which firmware is needed and whenever
> that can be loaded from the filesystem before calling
> remove_conflicting_devices() ?
> 

That's something that I did in amdgpu a few years back.

I pushed the identification and ability to load firmware into early init 
stages.  It means that if you have a brand new GPU and run a modern 
kernel with an older linux-firmware snapshot amdgpu will fail probe and 
your framebuffer from EFI keeps working.