Re: [Xen-devel] Catch crashing domains with GDB

[Simon Kagstrom <simon.kagstrom@xxxxxx>]

On 2005-11-16, 09:23, Kip Macy wrote:
> On 11/16/05, Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx> wrote:
> >
> >
> > >
> > > (gdb) target remote localhost:9999
> > > Remote debugging using localhost:9999
> > > Couldn't establish connection to remote target
> > > Remote communication error: Connection reset by peer.
> > >
> > > and the gdbserver then exits with
> > >
> > > Remote debugging from host 127.0.0.1 <http://127.0.0.1>
> > > Child exited with status 0
> > > GDBserver exiting
> >
> > This sounds like gdbserver getting confused about the crashed domain.
> > Perhaps Kip can suggest a fix...
> >
> 
> There are 2 possibilities, either one of the hypercalls used to query the
> state of domain is returning information that gdbserver doesn't understand /
> considers invalid or you've run off your stack. I wouldn't expect it to
> handle the latter with so little grace - but I haven't dealt with that
> condition in a long time.

Well, the stack should have been OK during the crashes (mostly things like
dereferencing NULL-pointers).

> Could you please try calling the shutdown/crash hypercall from some point
> where you are in a known good state to try and see if it works there? That
> would determine whether or not what you're seeing is an artifact of how the
> domain crashed. If that fails then I can reproduce it here and check in a
> fix when I submit my patch for SMP support.

I tried running

HYPERVISOR_sched_op(SCHEDOP_shutdown, SHUTDOWN_crash);

and attach the debugger to the domain with the same results as before.


Thanks for the help, attaching to the crashed domain would be very helpful!

-- 
// Simon

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