Re: xaa vs. WriteImage()

[Michael Lorenz]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Hello,

On Mar 6, 2008, at 18:02, Alex Deucher wrote:

On Thu, Mar 6, 2008 at 5:17 PM, Michael Lorenz  
<[EMAIL PROTECTED]> wrote:
-----BEGIN PGP SIGNED MESSAGE-----
 Hash: SHA1

 Hello,

 On Mar 6, 2008, at 16:40, Alex Deucher wrote:

On Thu, Mar 6, 2008 at 4:26 PM, Michael Lorenz
<[EMAIL PROTECTED]> wrote:
On Mar 6, 2008, at 15:58, Alex Deucher wrote:

On Thu, Mar 6, 2008 at 2:58 PM, Michael Lorenz
<[EMAIL PROTECTED]> wrote:
-----BEGIN PGP SIGNED MESSAGE-----
 Hash: SHA1

 Hello,

 On Mar 6, 2008, at 14:12, Alex Deucher wrote:

On Thu, Mar 6, 2008 at 2:00 PM, Michael Lorenz
EXA has prepare/finish access hooks for CPU access to  
buffers.  I
don't think XAA has anything similar.  There's also an  
wrapable FB
module, although I think it's only available in Xorg.

 I'll have a look at that - the main reason I'm using XFree86 is
that
 it's already working on NetBSD/sgimips, Xorg needs some more  
work
but
 I'll eventually do it.
 Hmm, some drivers access video memory through tiny apertures  
like
the
 VGA range - maybe I can do something like this - let the rest
of the
 Xserver render into my DMA buffer and then blit it in place.

Use shadowfb and hook in a custom shadowupdate() function.

 Wouldn't that interfere with XAA? If I could catch the framebuffer
 writes that bypass XAA that way that would solve my problem.
 Thanks!

Yeah, you gotta pick one or the other IIRC.  However for most modern
desktops you either have to be entirely SW or entirely HW or
performance sucks.  You lose if any sort of fallbacks cause a pixmap
migration to/from vram.

 In my case VRAM is RAM, and the CPU is pretty slow - I've had things
 running entirely SW and performance sucked. Not the slowest I've  
ever
 seen but nowhere near what the HW can do.
 Also, many X applications have trouble with the HW's native pixel
 format, cairo for instance just crashes. Using the DMA engine I can
 pretend it's using something more common - ABGR - and those
 applications just work fine. I think the next thing I'll try is to
 pretend that we're accessing VRAM through a small window, there must
 be prior art for that somewhere in the source tree.


the sgi impact driver I mentioned before
(http://cgit.freedesktop.org/xorg/driver/xf86-video-impact/) does
that.  IIRC, there's no way to access the vram directly so everything
gets sent to the card via dma.

Yeah, that's the software-only case. Interesting but I'd rather find  
a way to make this work while being able to use the rendering engine.

have fun
Michael
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.7 (Darwin)

iQEVAwUBR9B8FcpnzkX8Yg2nAQIe8Qf9FN2yZYRhGQv9f6B+ljBbkbIUx/8yXSe9
T9i4tMWGH5p1RnzoSU0GX8qHmmF8lm2ajMKI8yY496+Kma34NiPUN2QgrRJJrlen
yG2WOydYC1iqCYj+MA3pfJ3Nqns/xMJDj24BWVfpQGDDEHEaegjIcFpsXH5MW++W
dQbojEECbMFivSmTAuZ3u/YmfDskw6TqE+fTBGLLXurmnQY0lFok1IUeyS7dITuw
A5L2BJJMFjvP32uglb6LGUlw921Aj5o7kMEI7VBvJx8lgoTBPmT+lwXaacUbQ2iv
bG9+GFctpswI9nuI/CDNhvdKyMHlgUieYn9nHX90VQuGil02AvfpFw==
=t834
-----END PGP SIGNATURE-----
_______________________________________________
Devel mailing list
Devel@XFree86.Org
http://XFree86.Org/mailman/listinfo/devel