Bug#484583: xserver-xorg-video-nv: Failed to set up write-combining range
Ryo Furue wrote:
> | > I have this warning in my /var/log/Xorg.0.log :
> | >
> | > (WW) NV(0): Failed to set up write-combining range (0xd8000000,0x8000000)
> | >
> | > and this in /var/log/kern.log
> | >
> | > kernel: mtrr: type mismatch for d8000000,8000000 old: write-back new: write-combining
> | >
> |
> | Not sure this is actually a bug. The kernel is mainly responsible for
> | marking ranges as WC. But sometimes there are too many entries allocated
> | so Xorg cannot get a new one. And sometimes, the existing ranges are
> | difficult to modify to satisfy what Xorg wants.
> |
> | What does /proc/mtrr contains before and after starting X?
>
> I've just found a chance to restart my machine. I don't know an
> easy way of getting a status "before X", so I shut down the machine
> and booted to a single-user mode, where I copied the contents of
> /proc/mtrr to another file. I then exited, which brought the machine
> to the regular mode. I logged in from KDM to my regular session, and
> copied the contents of /proc/mtrr again.
>
> The result is that /proc/mtrr didn't change between before and after X
> and is
>
> reg00: base=0x00000000 ( 0MB), size=65536MB: write-back, count=1
> reg01: base=0xcff00000 (3327MB), size= 1MB: uncachable, count=1
> reg02: base=0xd0000000 (3328MB), size= 256MB: uncachable, count=1
> reg03: base=0xe0000000 (3584MB), size= 512MB: uncachable, count=1
> reg04: base=0xff0000000 (65280MB), size= 256MB: uncachable, count=1
>
> Does this info help?
>
I am not sure. The video memory range is included in the reg02 line
above. Maybe the kernel fails to split the range into a WC range for
your video board and the UC range for the other half. You might want to
look in your BIOS for some MTRR setup in case you can make the BIOS
setup different ranges at boot time.
Brice
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