Intel Xe driver on older platorms (Tiger Lake)

[matdibu]

There doesn't seem to be a consensus on whether Xe should be used on older platforms, like Tiger Lake

https://docs.kernel.org/next/gpu/rfc/xe.html#xe-platforms

The common/gpu/intel/tiger-lake/default.nix module enables Xe:

nixos-hardware/common/gpu/intel/tiger-lake/default.nix

Line 5 in b12e314

hardware.intelgpu.driver = lib.mkIf (lib.versionAtLeast config.boot.kernelPackages.kernel.version "6.8") "xe";

But Xe won't be loaded unless something like this is configured:

boot.extraModprobeConfig = ''
  options xe force_probe=9a60
  options i915 force_probe=!9a60
'';

The jury is still out on Xe stability, some call it trash, others call it perfect

So, should Xe be force_probe'd for Tiger Lake in nixos-hardware? or should it be avoided?

[Mic92]

We can enable it on selected devices where people tested it. Otherwise I would rely on kernel defaults.

[matdibu]

sure, but then this issue still stands
we're "enabling" it in the nix module, but it won't actually work on Tiger Lake unless force_probe'd

so that means we should take Xe out of nixos-hardware/common/gpu/intel/tiger-lake/default.nix (since the kernel defaults don't enable Xe on TGL) and let it be selected in device-specific modules, right?

[Mic92]

We should probably remove it from that file than.

[dimitarg]

FWIW, I ran a test on Alder lake, boot.kernelParams = [ "i915.force_probe=!46a6" "xe.force_probe=46a6" ];
For me, there's a 0.5 second screen tear during boot stage 1, reproducible consistently. Syslog is also full of warnings that this is not officially supported (mesa, etc).

Probably not worth it unless you know what you're doing, which I don't.