Vertical sync and KMS
sa at whiz.se
Sat Nov 20 08:08:40 PST 2010
On Sat, 2010-11-20 at 13:34 +0100, Sylvain Beucler wrote:
> Since the switch to KMS (Kernel Mode Setting) in the current Debian, I
> cannot get vertical sync to work with free 3D drivers.
> (Vertical syncs caps the game framerate to the physical screen's
> refresh rate, typically 60Hz, avoiding tearing and unnecessary display
> updates, and permitting smooth scrolling.)
> The only way to get vsync back is either use a proprietary driver or
> switch back to UMS (in either case: when that's actually possible). I
> tried with 2 ATI Radeon cards and an Intel one, using a simple
> scrolling demo with bare OpenGL, SDL 1.3 and Pyglet.
> Do you get this issue in other distros, and do you know what's the
It should work, for both radeon and intel, but I'm not sure if it's
supported in Mesa 7.8. You might need 7.9 from experimental.
Then either setting "vblank_mode=2" as an environment variable or or a
drirc configuration like the one below should give you vertical sync:
<device screen="0" driver="dri2">
<option name="vblank_mode" value="2" />
PGP Key ID 760BDD22
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