Patch adding supoort for X Double Buffer extension

[winden NTW]

>From: Samuel Rydh <samuel@ibrium.se>
>To: mol-devel@lists.maconlinux.org
>CC: windenntw@hotmail.com
>Subject: Re: Patch adding supoort for X Double Buffer extension
>Date: Sun, 11 Apr 2004 22:51:23 +0200
>
>On Sun, Apr 11, 2004 at 07:51:38PM +0000, winden NTW wrote:
> >
> > I'm attaching a patch I did today, please consider adding it for testing
> > purposes.
> >
>
>Thanks... but why would one want to double buffer the entire framebuffer?
>
>MOL tries very hard to refresh only portions of the display that has 
>changed
>(by utilizing the MMU and by checksumming) in order to reduce the amount of
>data that has to go through the AGP bus. As far as I can see, asking X to
>double buffer will (dramatically) increase the amount of data which
>has to be shuffled. A quick test on my machine shows that this is indeed
>what happens.
>
>As far as I can see, the only possibility to radically speed up the X11
>video driver is using offscreen VRAM for the framebuffer. Unfortunately,
>no good API exists for this (at least I haven't found it).
>
>/Samuel
>
>

Samuel, I've not yet tested mol-over-remote-x performance, perhaps it
will help when using a low-bandwidth channel, so that you get no partial
framebuffers.

Anyways, while doing this patch, I kept wondering about trying to
use an opengl texture for the mol framebuffer... Given proper driver 
support,
gl should place the framebuffer texture on AGP memory and then drawing
a polygon would update the screen.

Perhaps this would be a good path to follow...

Greets, Antonio.

ps. I've got a simple question... when running with xchecksum enabled, do
we checksum the whole screen or only the pages which are marked as dirty
by the mmu?

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