On Mon, 3 Sep 2001, Robert A. Knop Jr. wrote:
> I've got a 32MB AGP G450. I'm running Linux-2.4.9-ac6, with XFree86-4.1
> (the 0.20.0 RPMs from RedHat rawhide).
>
> My G450 works; I even have DRI working. However, I'm having some
> trouble with 2d acceleration in 24-bit mode.
> Looking at my logs, I do see another difference:
>
> 24-bit (32fbbpp):
>
> (II) MGA(0): Memory manager initialized to (0,0) (1600,2399)
> (II) MGA(0): Largest offscreen area available: 1600 x 1199
>
> 16-bit:
>
> (II) MGA(0): Memory manager initialized to (0,0) (1600,2400)
> (II) MGA(0): Largest offscreen area available: 1600 x 1200
>
> That's what's doing me in, isn't it? That *one bloody mising offscreen
> row* in 24-bit? Is that enough to all but disable all effective 2d
> acceleration.
>
> Sadness. And here was me thinking that 32MB was a lot of video RAM.
> (Indeed, doing the math, it would seem that only 8MB should be necessary
> to display a 4-byte deep screen at 1600x1200... which should leave
> plenty of memory left over for off-screen buffers and 3d buffers and
> such. What's up here?)
The code in mga_storm.c is trying to grab as much memory for textures as
possible (the author seems to value 3D performance above anything else).
I'm not convinced that it isn't grabing a little too much.
Perhaps it forgets to leave memory for the hardware cursor, in which case
option "swcursor"
might make a difference.
> (I've tried this both with and without Backing
> Store. For some annoying things, I do need Backing Store-- but it
> doesn't seem to help the speed to remove it, anyway.)
Backing store is off by default.
--
Dr. Andrew C. Aitchison Computer Officer, DPMMS, Cambridge
[EMAIL PROTECTED] http://www.dpmms.cam.ac.uk/~werdna
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