Am 03.04.2018 um 10:36 schrieb Michel Dänzer:
On 2018-04-01 07:45 PM, Ilia Mirkin wrote:
On Sun, Apr 1, 2018 at 1:39 PM, Christian König
<christian.koenig@xxxxxxx> wrote:
Am 30.03.2018 um 22:45 schrieb Takashi Iwai:
amdgpu driver lacks of modeset module option other drm drivers provide
for enforcing or disabling the driver load. Interestingly, the
amdgpu_mode variable declaration is already found in the header file,
but the actual implementation seems to have been forgotten.
This patch adds the missing piece.
NAK, modesetting is mandatory for amdgpu and we should probably remove the
option to disable it from other DRM drivers without UMS support as well
(pretty much all of them now).
If you want to prevent a driver from loading I think the correct way to do
so is to give modprobe.blacklist=amdgpu on the kernel commandline.
That would remove the possibility to prevent the driver from loading when it
is compiled in, but I don't see much of a problem with that.
Having a way to kill the graphics driver is a very useful debugging
tool, and also a quick and easy way to get out of an unpleasant
situation where graphics are messed up / system hangs / etc. The
modprobe blacklist kernel arg only works in certain environments (and
only if it's a module).
Building amdgpu into the kernel isn't feasible for a generic kernel such
as a distro one, because it would require including all microcode into
the kernel as well (12M right now, and growing).
If a user decides to build amdgpu into their custom kernel and runs into
trouble due to that, that's "doctor, it hurts if I do this" territory.
Correct, but I agree that even in this situation it would be very
helpful to prevent the gfx drivers from loading and fallback to
efifb/vesafd (or whatever the platform provides).
It's just that the "nomodeset" and "amdgpu.modeset=0" options are really
not well named for this task.
Christian.
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