Any way to trigger system_powerdown from a signal?

[Brett Neumeier]

I'm trying to set up supervision for a QEMU virtual machine on a machine that 
uses s6 and s6-rc for service management.

I currently have my QEMU configured so that it shuts down gracefully when the 
"system_powerdown" monitor command is executed. With s6, though, the only 
idiomatic way that I can get the supervision frameowork to shut down a 
long-running process is to send it a signal. I've verified that I can get QEMU 
to terminate by sending it a SIGINT, SIGTERM, or SIGPWR; but all of those just 
cause it to terminate, they don't send an ACPI shutdown request to the guest 
operating system.

Is there any way to trigger the same "system_powerdown" mechanism by sending 
QEMU a signal? If not, can anyone suggest a way to add a signal handler that 
does that?

Cheers!

-- 
Brett Neumeier <random@freesa.org>