Adding mesa from nixpkgs-unstable to a stable flake config

[ElvishJerricco]

See here:

Updating to mesa 25.0.2

So, unstable has somewhat recently shaken up how mesa is used in NixOS. Before these changes, it was technically unsafe to mix channels, because packages would be linked to the version of libgbm provided by the mesa in nixpkgs, and the drivers provided by the host system would require the libgbm from the host’s version of mesa. It was often the case that this would work out, but it certainly wasn’t guaranteed. The recent change is that the libgbm linked to by applications now is only a stub tha…

TL;DR: Unstable and 24.11 just don’t mix when it comes to graphics, but 25.05 onward should have that problem pretty much solved.

You have the additional complexity that you’re trying to change mesa in an overlay. This is adding extra problems because changing mesa results in a mass rebuild in nixos 24.11 (which will no longer be the case in 25.05, though there will be better ways to change the drivers than an overlay). Given the change in packaging since mesa 24.3 and the change in linkage, you’re just not going to reasonably be able to get a 24.11 system to build with an overlay changing mesa to the build from unstable.

My advice is to stick with unstable until 25.05 releases. The good news is that then you can probably stick with 25.05 and still get driver updates from unstable.