RANDR 1.2 heads up

[Adam Jackson]

On Wed, 2007-03-14 at 20:12 -0400, Thomas J. Baker wrote:
> On Mon, 2007-03-12 at 16:35 +0100, Tomas Janousek wrote: 
> > Hi,
> > 
> > On Mon, Mar 12, 2007 at 11:09:34AM -0400, Adam Jackson wrote:
> > > The display size is limited at server startup, because XAA's memory
> > > allocator is spectacularly bad.  I don't know if there's a good
> > > workaround for this.  Try setting a Virtual size in the Screen section
> > > of xorg.conf?
> > 
> > Yeah, you have to use Virtual to specify the maximum size. It may not be
> > possible to specify more than 2048xSomething though, because some chips are
> > limited (at least I read this on some xorg maillist). I just ended up aligning
> > the screens vertically, but it may not be comfortable.
> > 
> > Regarding the 1920x1200 resolution, did you specify that Monitor-VGA option in
> > the device section?
> > 
> > -- 
> > TJ., BaseOS, Brno, CZ
> > 
> 
> I did have some luck with this after setting a virtual size. I was able
> to add the external panel on the fly. Unfortunately I lose direct
> rendering with the virtual size set to 3200x1200:
> 
> (EE) intel(0): Cannot support DRI with frame buffer width > 2048.
> 
> In theory, isn't the driver supposed to allocate as much shared memory
> as it needs? (i945 hardware). Is this something that will get fixed or a
> limitation of the hardware?

Hardware limitation.  3D engines only have so many address bits...

965 has a stride limit of 4096, I think, which is quite a bit better.
Fixing this for the general case is hard but doable.  Imagine the pain
involved in submitting all your rendering multiple times in squares of
2048x2048 and you begin to get some idea of the contortions involved.

- ajax