Re: [Qemu-devel] [Bug 1217339] [PATCH] Unix signal to send ACPI-shutdown to Guest

[Daniel P. Berrange]

On Wed, Mar 15, 2017 at 06:00:40PM +0000, Peter Maydell wrote:
> On 15 March 2017 at 17:46, Simon <address@hidden> wrote:
> > OK for not using SIGHUP and keep SIGTERM, SIGINT and SIGHUP to have the
> > same behavior.
> >
> > SIGQUIT is reserved for core files generation.
> >
> > SIGUSR1 is already used in 'util/qemu-progress.c' to trigger a report
> > on ongoing jobs, so it does not seem usable.
> >
> > SIGUSR2 is temporarily used in 'util/coroutine-sigaltstack.c' which
> > takes care however to preserve the original handler. I did not saw
> > any other place where it is used, so it seems to be a better candidate.
> 
> I don't think we can use SIGUSR2 here -- as you say, it's used
> in the sigaltstack version of coroutines, and so there would
> be races if the user tried to use SIGUSR2 to power down the
> machine while we happened to be starting a new coroutine.
> 
> SIGUSR1 is also no good, as it is used by main-loop.c as
> the SIG_IPI.

Which means we'd be into the realm of having to pick  SIGRTMIN + N for
some arbitrary N >= 0


Regards,
Daniel
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