Re: [Xen-devel] Early ACPI events prevent subsequent ACPI functionality on xen 4.3 + HVM domU

[Alex Bligh <alex@xxxxxxxxxxx>]

George,

--On 21 May 2013 16:23:00 +0100 George Dunlap <george.dunlap@xxxxxxxxxxxxx> 
wrote:
> On 05/21/2013 04:16 PM, Alex Bligh wrote:
> > George,
> >
> > --On 21 May 2013 14:39:55 +0100 George Dunlap
> > <George.Dunlap@xxxxxxxxxxxxx> wrote:
> >
> > > So this appears to be an xl toolstack thing.  I managed to reproduce
> > > your results using "xl shutdown -F [domain]"; but if you then do "xl
> > > trigger [domian] power", the domain shuts down as normal.
> > OK. But doesn't the power thing yank the power rather than send a
> > clean shutdown?
> No -- if you push the button just once on most modern hardware it will
> send an ACPI "poweroff" event that the OS handles gracefully.  That's
> what gets sent when you do "xl trigger [domain] power".  If the OS
> ignores it (either on real hardware or virtual hardware) nothing happens.
> On real hardware you have to then hold down the button for 5 seconds for
> a hard-shutdown, with xl you have to do "xl destroy".
OK, great. I am guessing the reason why 'xl shutdown' doesn't do
that is to cope with (a) non-HVM domains, and (b) old fashioned
HVM domains with PV support but not ACPI support. Correct?

> > We are using libxl here (admittedly having looked carefully at
> > the xl code for guidance) and get the same problem.
> The relevant xl code is here:
>
>      rc=libxl_domain_shutdown(ctx, domid);
>      if (rc == ERROR_NOPARAVIRT) {
>          if (fallback_trigger) {
>              fprintf(stderr, "PV control interface not available:"
>                      " sending ACPI power button event.\n");
>              rc = libxl_send_trigger(ctx, domid, LIBXL_TRIGGER_POWER, 0);
>          } else {
>              fprintf(stderr, "PV control interface not available:"
>                      " external graceful shutdown not possible.\n");
>              fprintf(stderr, "Use \"-F\" to fallback to ACPI power
> event.\n");
>          }
>      }
>
> It looks like libxl_domain_shutdown() will only use the PV shutdown
> method.  If that method is not available, then it will call
> libxl_send_trigger().
OK. Well if that's the case, why is it not working? i.e. how
is using 'xl trigger power' a workaround? As our testing was
on xl (as well as libxl). Perhaps libxl_domain_shutdown
is returning an error other than ERROR_NOPARAVIRT or no error
at all?

The major problem for us isn't that the initial domain
shutdown doesn't work (that's just a bit sad), it's that it blocks
subsequent shutdowns from working.

> What does your code do?  Does it call libxl_domain_shutdown(), or
> libxl_send_trigger() (or one then the other, like xl)?
When Diana reported the bug, she was using xl (and thus the
code you are using above).

Our libxl code currently just calls libxl_domain_shutdown.
Apparently we didn't look too closely at xl :-)

Does xl trigger reset do the same thing (i.e. a graceful shutdown)?
If not we'd also (I think) have to recode reboots to do a power trigger
then a restart.

--
Alex Bligh

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