Re: x86, nops settings result in kernel crash

From: Alan Cox
Date: Thu Aug 16 2012 - 14:49:07 EST


On Thu, 16 Aug 2012 14:45:15 -0400 (EDT)
Tomas Racek <tracek@xxxxxxxxxx> wrote:

> ----- Original Message -----
> > On Thu, Aug 16, 2012 at 09:35:12AM -0400, Tomas Racek wrote:
> > > Hi,
> > >
> > > I am writing a file system test which I execute in qemu with kernel
> > > compiled from latest git sources and running it causes this error:
> > >
> > > https://bugzilla.kernel.org/show_bug.cgi?id=45971
> > >
> > > It works with v3.5, so I ran git bisect which pointed me to:
> > >
> > > d6250a3f12edb3a86db9598ffeca3de8b4a219e9 x86, nops: Missing break
> > > resulting in incorrect selection on Intel
> > >
> > > To be quite honest, I don't understand this stuff much but I tried
> > > to do some debugging and I figured out (I hope) that the crash is
> > > caused by setting ideal_nops to p6_nops (k8_nops was used before
> > > the break statement was added).
> >
> > Maybe I overlooked it or maybe it was implied but did you try
> > reverting
> > the patch and rerunning your test? Does it work ok then?
> >
>
> Yes, if I remove the break statement (introduced by this commit), it works fine.

What version of qemu is this - do we have qemu bug here I wonder.

Alan
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