RandR bugs

Thomas Winischhofer thomas at winischhofer.net
Thu Sep 29 16:59:17 PDT 2005

Hash: SHA1

Alan Hourihane wrote:
> I'm certainly open if NVIDIA has some code or comments to share here
> Andy on how NVIDIA's driver deals with RandR and TwinView.

I can't speak for Nvidia, but the sis driver (and the radeon, if Alex
took over all it needs) deals very well with MergedFB + RandR.

There is one little issue, namely identically looking metamodes (ie meta
modes that consist of different modes for the output devices, but look
the same to the server, eg 1280x1024-1024x768 and 1024x768-1280x1024). I
work around the problem that RandR ignores the second one of these modes
(because it thinks that they are identical) by giving the second one a
different rate.

Also, MergedFB with pseudo-Xinerama works well in combination with
RandR. Window managers are smart enough nowadays to re-query the
Xinerama extension upon a screen size change. So I simply change the
Xinerama info at appropriate times. KDM/Kwin works wonderfully with
this, and I had positive reports on gdm and a few others as well.

Putting together (real) Xinerama and RandR is assumingly a bit more
complicated. Xinerama with its fixed "screen"-boundaries is a real
problem for RandR, I can imagine.

Andy, does the Nvidia driver support rotation in TwinView mode? I have
been thinking about this, but it's logically somewhat beyond me yet,
especially when it comes to non-rectangular screens.


- --
Thomas Winischhofer
thomas AT winischhofer DOT net          http://www.winischhofer.net/

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