Mtrr doesn't work

Herodot · Posted: Tue Aug 13, 2002 8:02 pm Post subject: Mtrr doesn't work

Hi All.

I'm running Gentoo, and it's very fast and stable.

My system: XP1800+, Abit kr7a-raid (via266), 512MB, Geforce 2 MX

I'm using the Gentoo kernel (sys-kernel/gentoo-sources). Ext3, no preempt. People talk of "low latency" - I don't remember that from menuconfig.

If I compile the kernel with mtrr, I can't emerge nvidia-kernel. It fails with unresolved symbols. Mtrr can presumably boost graphics speed a lot. I get about 900 in glxgears (1600x1200x32). On Standard redhat on the same system I get about 1400.

Some people use mtrr without problems. What's wrong?

On the same note: framebuffer. There is a lot of rather confusing advice on this. I simply want lightening fast graphics, and preferably a vga boot. Has anybody managed to find a viable solution for a similar system?

Thanks,
H

BonezTheGoon · Posted: Tue Aug 13, 2002 8:39 pm Post subject:

Searching through these forums indicate that framebuffer support on nvidia cards and using the nvidia drivers cause issues. As near as I have been able to make-out you should leave framebuffer alone and wait for a fix. As for your mtrr support you should consult the forums and specifically this README found on nvidia's site that covers AGP/MTRR support issues.

Hope that helps!

Regards,
BonezTheGoon

Herodot · Posted: Wed Aug 14, 2002 1:12 am Post subject:

Yes, framebuffer definately spells trouble. I leave it for now.

Mtrr: I've not found any good answers anywhere, sadly. I've just been through 25 kernel compiles, and these's no way I can enable mtrr.

The readme from nvidia doesn't mention mtrr, nor do their forums. Google doesn't help much either.

Oh well...

Thanks,
H

BonezTheGoon · Posted: Wed Aug 14, 2002 2:24 am Post subject:

I have heard some different myths/rumors about mtrr/nvidia/smp/ram-size have you got smp enabled? Do you have dual processors? You might try disabling smp if you can.

Regards,
BonezTheGoon

Herodot · Posted: Wed Aug 14, 2002 1:59 pm Post subject:

pjp · Administrator Joined: 16 Apr 2002 Posts: 20067

Check this out for info on compiling without SMP. This thread offers a solution to a potential problem you might run into.
_________________
Quis separabit? Quo animo?

Herodot · Posted: Thu Aug 15, 2002 12:46 pm Post subject:

I can't compile without smp. If I adjusted 100+ other settings then maybe... but I'll leave this for now. Strange though it is.

- H

DesertFox · n00b Joined: 14 Nov 2002 Posts: 53

For general support about whether or not mtrr is currently running, type

cat /proc/mtrr

and if your graphics card is using it, you should see a setting with your graphics card's memory amount (like 32 mb)

info about adding more lisings is

/usr/src/linux/Documentation/mtrr.txt

more of a read here

http://dvd.sourceforge.net/xine-howto/en_GB/html/howto-9.html

Malakin · Posted: Mon Dec 16, 2002 1:06 am Post subject:

I've never compiled in smp support and I've always used mtrr with Nvidia. Never had a problem.

You could try vanilla sources if you haven't already, which is what I've always used.

Vancouverite · Posted: Mon Dec 16, 2002 1:13 am Post subject:

I have an Athlon 1.4GHz, MSI-K7T-Turbo (kt133a), 384MB, GeForce2 MX400 and I have both mtrr and frame buffer working great. I suspect your mtrr problems are related to the smp issue. Also I am using the lolo-sources kernel. Here is how to get the frame buffer working. I am using 1280x1024@16bpp.

1) Compile in support for the following:
Console drivers > VGA text console and Video mode selection support

Frame-buffer support > Support for frame buffer devices
VESA Vga graphics console
Advanced low level driver options
Monochrome support
2,4,8,16,24,32 bpp support

2) Activate the frame buffer and set it's resolution by passing options to the kernel. These are the options I pass to my kernel:
"vga=794 video=vesa:ywrap,mtrr"

This selects mode 1280x1024@16bpp using vesa frame buffer enabling scrollback and the use of mtrr to speed things up. When you set this up you should set "vga=ask" so when you boot you will be prompted to enter a mode manually. When you are prompted to enter a mode the number you enter must be hexadecimal. When you have found the mode you like best you must convert this hexadecimal number into decimal and put this decimal number into the "vga= ".
For instance 031A in hex is 794 decimal. For a list of VESA modes check out the framebuffer howto:
http://www.tahallah.demon.co.uk/programming/Framebuffer-HOWTO-1.2-5.html