Re: Early ACPI events prevent subsequent ACPI functionality on xen 4.3 + HVM domU

[George Dunlap <george.dunlap@eu.citrix.com>]

On 05/21/2013 04:16 PM, Alex Bligh wrote:
> George,
>
> --On 21 May 2013 14:39:55 +0100 George Dunlap
> <George.Dunlap@eu.citrix.com> 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".

> 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().

What does your code do?  Does it call libxl_domain_shutdown(), or 
libxl_send_trigger() (or one then the other, like xl)?

  -George