Re: [Xen-devel] SHUTDOWN_crash and vcpu deferrals

[John Levon <levon@xxxxxxxxxxxxxxxxx>]

On Fri, Feb 20, 2009 at 09:35:16PM +0000, Keir Fraser wrote:

> Hm. If qemu is down you're kind of screwed anyway.

You're totally screwed. But what happens today is this: you get some
weird message about sentinels in xend.log (if you happen to read it),
and a domain state that looks like this:

domu-224                        2  1024     1     ------ 0.0

which is not exactly very useful. But we detect qemu failures now in
xend. So we turn on this code:

        # ideally we would like to forcibly crash the domain with
        # something like
        #    xc.domain_shutdown(self.vm.getDomid(), DOMAIN_CRASH)
        # but this can easily lead to very rapid restart loops against
        # which we currently have no protection

(The comment being completely incorrect), but then the crash doesn't
work because of the bug I pointed out.

All I want to do is mark a domain without a qemu process as crashed. Is
that clearer?

And yes, it's pretty trivial to make qemu break. Most typically by
passing bogus parameters (say, a broken kernel image, an incorrect NIC,
etc.)

regards,
john

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