[Nix-dev] Re: How to unleash your ATI graphics card on NixOS

[Peter Simons]

Hi Eelco,

 > Is there a reason why we have a separate ATI kernel? In other words,
 > is there a downside to turning on CONFIG_DRM_RADEON_KMS in the main
 > 2.6.38 kernel?

there are two issues that should be considered: (a) it's a brand-new
driver and (b) it needs additional firmware. Personally, I don't mind
activating it by default, obviously, since I'm using it anyway.

 > Udev should automatically grant ownership to such devices to
 > logged-in users (unless there is a security problem in doing so).
 >
 > Something like this should do the trick:
 >
 >   services.udev.extraRules =
 >     ''
 >       SUBSYSTEM=="dri", TAG+="udev-acl"
 >     '';
 >
 > only I don't know what the match (SUBSYSTEM==...) should be.

Yes, it would certainly be nice if udev would do that automatically. The
"permission denied" error I got initially was very hard to find, because
it is buried somewhere in a 40+ KB slim.log file. In fact, I didn't even
find it, the guys on #radeon did. :-)

Take care,
Peter