Re: [Xen-devel] dom0 pvops crash

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Mon, Jan 25, 2010 at 06:26:26PM +0000, Ian Campbell wrote:
> On Mon, 2010-01-25 at 18:18 +0000, Ian Pratt wrote:
> > > Here's the hacky fix from last summer:
> > > http://lists.xensource.com/archives/html/xen-devel/2009-06/msg00519.html
> > > 
> > > On my testbox I can trigger that bug just by compiling a kernel in dom0.
> > > 
> > > CONFIG_HIGHPTE=n is stable for me, while CONFIG_HIGHPTE=y most probably
> > > makes dom0 crash during a kernel compile.
> > > 
> > > (dom0 and Xen are 32bit PAE)
> > 
> > Even if it worked reliably, CONFIG_HIGHPTE performance would be
> > miserable: It takes an operation that is always going to be slow on
> > any virtualized system (updating PTEs), and pounds the cr*p out of
> > it...
> 
> Unfortunately distros tend to enable it on native and with pvops there
> is often no separate Xen kernel build where it can be disabled.
> 

I just noticed the default Fedora 12 32bit PAE kernel has CONFIG_HIGHPTE=y.
Running simple "make -j2 bzImage && make -j2 modules" in the guest crashes the 
kernel.

Some kind of workaround should be made..

-- Pasi


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