Re: Re: [Xen-users] pv_ops kernel and nvidia binary driver

[Jeremy Fitzhardinge <jeremy@goop.org>]

On 07/11/09 23:03, Boris Derzhavets wrote:
> A while ago Jeremy responded the same question.
> Per Jeremy:-  unmodified binary Nvidia driver would crash under Xen.
> Modified driver should in the pvops kernel.
>
> It's also my major concern as well.
>
> Boris
>
> --- On *Sun, 7/12/09, Michael Ralston /<michael@ralston.id.au>/* wrote:
>
>
>     From: Michael Ralston <michael@ralston.id.au>
>     Subject: [Xen-users] pv_ops kernel and nvidia binary driver
>     To: xen-users@lists.xensource.com
>     Date: Sunday, July 12, 2009, 1:48 AM
>
>     Just wondering what it will take to get the nvidia binary driver
>     working on a pv_ops kernel.
>
>     It makes it difficult to debug without the source to the nvidia
>     driver, but I think it should be possible to get it to work without
>     changing the binary driver. If the dom0 kernel had access to all the
>     resources that a bare metal kernel did, then it should work right?
>

The problem comes down to whether the nvidia driver assumes the kernel's
(pseudo-)physical addresses are really machine physical or not.  If it
doesn't do the appropriate conversions between physical and machine
addresses using the standard Linux DMA API (or similar), then it will
end up misprogramming the hardware and reading/writing random memory. 
There's not a lot we can do about that if that happens within the binary
part of the nvidia driver.  If the binary code calls out to the
source-available parts of the driver to do those conversions, then it
would be possible to fix there.

There are other potential pitfalls the nvidia driver could be falling
into, but that's the most likely.

    J