I've got the hint that I can speed up access to VESA graphics memory on P4s by setting a MTRR.

Before I dig into the Intel Manuals, has anyone a sample how to enum the current MTRRs and possibly to set them?

Posted on 2005-12-19 13:22:48 by japheth

Now I wrote a small tool which display current variable MTRRs and allows to modify the values. Works in win9x (and on native DOS with HX) only.

Posted on 2005-12-20 06:19:06 by japheth
IIRC f0dder wrote some driver to access MSRs in ring3. Don't know why, but I can't find it on his site.
Posted on 2005-12-20 11:28:49 by MazeGen
I guess I should upload it to http://f0dder.reteam.org - but the ring3 MSR service is attached to this post. It doesn't contain any info for accelerating video access, though... the actual MSRs will depend on your CPU (though I think the MSRs are the same for all CPUs that supports it). A few DOS VESA demos might support it, or you can probably find info in linux drivers.
Posted on 2005-12-20 12:48:22 by f0dder


it's clear to me what to do to speed vesa video memory access, dont need any more infos.
Posted on 2005-12-20 14:00:44 by japheth