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 Wed, 2012-10-03 at 10:03 +0100, Sander Eikelenboom wrote:
> Tuesday, October 2, 2012, 4:02:18 PM, you wrote:
> 
> > On Thu, 2012-09-27 at 21:11 +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.
> >> 
> >> > Or something like that, I've not actually implemented it ;-)
> >> 
> >> > Ian.
> >> 
> >> It's time to call defeat, without proper C skills it seems a bit too
> >> hard to figure it out.
> 
> > That's ok, I'll add it to my TODO to pickup where you left off (unless
> > someone beats me to it).
> 
> Thx !
> Would be nice for 4.2.1 since the xendomains stop script doesn't
> function properly with xl as toolstack, and not shutting down the
> domains but just pulls the plug.

Agreed.

> Would it be helpful to you, to send the doc patches as well ?

Absolutely!

> 
> 
> > Thanks for taking it this far! FWIW you seemed to be pretty close.
> 
> >> Can't seem to get the hang of how to keep a reference to
> >> libxl_evgen_domain_death and use it to check if the domid of the event
> >> is the same as that from a domain we are waiting to shutdown.
> >> The rest of the code doesn't give me much pointers since all commands
> >> seem to operate on a single domid at once.
> >> 
> >> The concoction below leads to:
> >> xl_cmdimpl.c: In function Ãshutdown_domainÃ:
> >> xl_cmdimpl.c:2766: error: dereferencing pointer to incomplete type
> 
> > In case you are interested this is because the libxl_evgen_domain_death
> > type is opaque to users of libxl so constructs like
> > domains_wait_shutdown[i]->domid are not possible.
> 
> > The answer is to use the 3rd argument to libxl_evenable_domain_death
> > (the one of type libxl_ev_user) to pass a "closure", this value is
> > returned in the event's "for_user" field. The application can use this
> > to store data specific to this particular event -- in this case it would
> > probably be sufficient to just pass the domid here but in principal one
> > could pass a pointer to any datastructure.
> 
> Thanks for the explanation, although i still don't see how to actually change 
> the code the right way.
> 
> 
> > Thanks again,
> > Ian.
> 
> 
> 
> 
> 



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