Re: port-xen/47057: Xen NetBSD DomU file system trash under Linux Dom0

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Sun, Oct 21, 2012 at 07:47:38PM +0200, Roger Pau Monné wrote:
> On Sun, Oct 21, 2012 at 1:29 PM, Manuel Bouyer 
> <bouyer%antioche.eu.org@localhost> wrote:
> > OK, here's another patch, which also checks that the mapping doesn't
> > change. But I wonder is the corruption occurs on the NetBSD side.
> > Could you also add some debugging code on the other side ?
> 
> Still no luck with the new patch, I've been looking at the Linux code,
> and the attached patch (taken the idea from Linux) mitigates the
> problem, but we still have it.

Does linux do this silently, or does it complain when the ring
corruption occurs ?

> I've also added the trace and verbose
> options to xenstored running in the Dom0, and there's no sign that
> anyone is writing to xenstore when the crash happens.
> 
> Is it possible that someone writes to the machine address
> xen_start_info.store_mfn and is there anyway to check that nobody is
> mapping this ma to another va?

I've been thinking about checking this, but it's harder to do.
Maybe it's easier to do this check in the hypervisor ?

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--