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Old 02-03-13, 07:23 AM   #3
pigeon
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Join Date: Jul 2004
Posts: 57
Default Re: MTRR support in recent driver/card?

Quote:
Originally Posted by brebs View Post
Take a look:
Code:
cat /proc/mtrr
See if the kernel can fix it:
Code:
$ zgrep MTRR /proc/config.gz 
CONFIG_MTRR=y
CONFIG_MTRR_SANITIZER=y
CONFIG_MTRR_SANITIZER_ENABLE_DEFAULT=1
CONFIG_MTRR_SANITIZER_SPARE_REG_NR_DEFAULT=1
Or try to fix it manually.
I already looked at those. I fixed it for my onboard intel graphics, but nvidia seems to be not using MTRR at all.

Quote:
Originally Posted by brebs View Post
I dunno whether Option "IndirectMemoryAccess" "False" in xorg.conf would help.
Just tried, doesn't make a difference.

I have even tried manually adding the MTRR write-combining registers to match what the nvidia card is, but it just doesn't seem to be used.


Quote:
Originally Posted by brebs View Post
Why are you giving yourself this problem by not enabling PAT?
I'm trying to use the nvidia card under Xen Dom0. The PAT support in the Xen Dom0 has some big issues and has been disabled. I ended up digging up some old MTRR Xen patches and seems to have got MTRR enabled in Dom0. Now the last step is to get nvidia to use MTRR.

And, yes yes, I know nvidia's driver + Xen has always been an issue for most non-Quadro cards. I'm just trying to do my best here. At least if I can see the nvidia drver is actually using MTRR then I'll be happy even if it doesn't boost the performance.

If someone from nvidia can confirm that MTRR is not being used anymore at all then that's also a good answer too.

Thanks for your suggestions too btw.
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