Re: [Xen-devel] What is the current state of Dom0 kernel support? / crash with 2.6.31-rc5 32bit PAE

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Mon, Aug 10, 2009 at 10:27:50PM +0300, Pasi Kärkkäinen wrote:
> On Mon, Aug 10, 2009 at 09:52:35AM -0700, Jeremy Fitzhardinge wrote:
> > On 08/10/09 09:43, Pasi Kärkkäinen wrote:
> > > Did I mess up something here or was this patch against some other tree 
> > > than
> > > rebase/master? 
> > >   
> > 
> > No, it needed another change in there.  rebase/master now has that fix
> > in it, but I'm seeing other interrupt-related strangeness which I still
> > don't understand.  I'd be interested in any reports you have about
> > current rebase/master.
> > 
> 
> I just updated rebase/master and rebuilt (now 2.6.31-rc5).
> 
> http://pasik.reaktio.net/xen/pv_ops-dom0-debug/pv_ops-dom0-log-11-rebase-master-with-highpte.txt
> 
> (gdb) list *0xc058c93f
> 0xc058c93f is in active_evtchns (drivers/xen/events.c:237).
> 232
> 233     static inline unsigned long active_evtchns(unsigned int cpu,
> 234                                                struct shared_info *sh,
> 235                                                unsigned int idx)
> 236     {
> 237             return (sh->evtchn_pending[idx] &
> 238                     cpu_evtchn_mask(cpu)[idx] &
> 239                     ~sh->evtchn_mask[idx]);
> 240     }
> 241
> (gdb) 
> 
> 

I just added some debug printk()'s to the very beginning of the function and 
found out this:

DEBUG active_evtchns: cpu: 0, sh: 4117237760, idx: 0
DEBUG sh->evtchn_pending: 4117239808, sh->evtchn_mask: 4117239936
DEBUG cpu_evtchn_mask(cpu): 0

so.. looks like the buggy piece of code (null pointer dereference) is: 
cpu_evtchn_mask(cpu)[idx]

-- Pasi

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