Re: [Xen-devel] [PATCH 0 of 3] xl and hotplug: Introduce and use shutdown and reboot xm compatibility options

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2012-09-25 at 16:47 +0100, Sander Eikelenboom wrote:
> Tuesday, September 25, 2012, 5:29:09 PM, you wrote:
> 
> > On Tue, 2012-09-25 at 16:11 +0100, Sander Eikelenboom wrote:
> 
> >> The only relative simple implementation i thought of was direct
> >> shutting down all, and when the -w parameter was set, just loop and
> >> wait on events until the only running domain is domain-0.
> >> Although this exactly does what has to be done, it somehow sounds a
> >> bit dirty.
> 
> > I think you can allocate an array of libxl_evenable_domain_death*, of
> > nr_doms in size and then as you shutdown each domain call
> > libxl_evenable_domain_death for it too.
> 
> > Then you loop waiting for destroy events, calling
> > libxl_evdisable_domain_death as each domain dies, while counting back
> > from nr_doms until 0. When it reaches 0 everything you asked for has
> > been shutdown.
> 
> Depends a bit on what you expect -a to do, especially in combination with -w.
> The wait gives quite a window for a new guest to be created in the mean time.
> 
> The usage in the init.d/xendomains script is as a sort of "catch all", since 
> the iteration is in the script it self.
> So for that purpose i would assume that a "xl shutdown -a -w" would
> shutdown all domains until only dom-0 remains, and not only shutdown
> the domains that were running at the time the command was actually
> issued.

I'd be happy to assume that no one is starting new domains while the
system is in the process of shutting down...

Or maybe we could just drop a marker in xenstore to prevent new domains
being started. Sort of like how initscripts create /nologin to stop new
loggins during shutdown.

Ian.



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