Re: XEN MTRR

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Thu, Jun 07, 2012 at 08:49:37PM +1000, aorchis@gmail.com wrote:
> On Wed, Jun 6, 2012 at 2:17 AM, Konrad Rzeszutek Wilk
> <konrad.wilk@oracle.com> wrote:
> > On Sun, Jun 03, 2012 at 05:31:32PM +1000, aorchis@gmail.com wrote:
> >> Hi Jeremy and Konrad,
> >
> > CC-ing xen-devel.
> >
> >>
> >> Basically the driver NVIDIA provided is a binary blob and recent
> >> versions does not work with the PAT layout of XEN so it falls back to
> >> MTRR to provide write combining (please correct me if I'm wrong).
> >
> > OK? Which is still OK. Are you using a v3.4 kernel with an up-to-date
> > NVidia driver? I've had reports that it works OK.
> 
> I briefly tried kernel 3.4 to see if the problem is fixed but it's not.
> I used v3.4 kernel with NVIDIA driver v295.49 and a beta version
> (v302) but both didn't work.
> 
> When the nvidia module is loaded, it prints out an error message:
> "NVRM: PAT configuration unsupported, falling back to MTRRs."
> 
> When I launch Xorg, the screen turns blank then the monitors powered down and my
> box hard crashed, I had to hold the power button to turn it off.

Ok, lets CC Ben - he might have more up-to-date information. Also
you might want to setup a serial console to capture the kernel to see
where it crashes.

> 
> This only happens in dom0 under XEN, if I run my dom0 by itself then
> the nvidia module loads fine.
> 
> >> However there is no MTRR support on XEN so the driver hard crashed my
> >> machine (I can't ssh into the box anymore).
> >>
> >> Moreover, there is problem with the open source driver 'nouveau' for
> >> NVIDIA card  (also has something to do with PAT layout of XEN) which
> >> causes memory corruption.
> >
> > Huh? Can you point me to a bugzilla please? There was a corruption
> > issue where you can pass in 'nopat' on the command line.
> 
> Yes, that is the issue I was referring to, I had to pass "nopat" to
> GRUB in order
> to fix it.

Ok, so there is afall back for you.