Hi,
On 07/14/2011 10:30 PM, Peter Simons wrote:
The radeon driver used in Linux by default does not support 3D hardware
rendering on modern ATI chips, like RS880 (Radeon HD 4250). Everything
seems to works fine, but 3D graphics are slow, because rendering actually
takes place on the CPU:
$ glxinfo | grep renderer
OpenGL renderer string: Software Rasterizer
Now, to improve graphics performance a *lot*, you need to enable the new
radeon driver in your kernel by setting CONFIG_DRM_RADEON_KMS=y. A kernel
that has been built with that feature is already included in nixpkgs; just
add the lines
boot.kernelPackages = pkgs.linuxPackages_2_6_38_ati;
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?
Any user who wants to perform hardware rendering must be a member of the
'video' group
groupmems -g video -a your_username_here
..., otherwise they won't be able to read/write the devices in /etc/dri/.
(I assume you mean /dev/dri.) 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.
After you've made those changes, run "nixos-rebuild boot", and reboot. Now
you'll see:
$ glxinfo | grep renderer
OpenGL renderer string: Mesa DRI R600 (RS880 9715) 20090101 TCL DRI2
Great :-)
--
Eelco Dolstra | http://www.st.ewi.tudelft.nl/~dolstra/
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