Re: [Qemu-devel] [Bug 1217339] [NEW] SIGQUIT to send ACPI-shutdown to Guest

From: Laszlo Ersek <lersek@redhat.com>
To: Bug 1217339 <1217339@bugs.launchpad.net>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [Bug 1217339] [NEW] SIGQUIT to send ACPI-shutdown to Guest
Date: Tue, 27 Aug 2013 16:38:37 +0200	[thread overview]
Message-ID: <521CB9ED.4030802@redhat.com> (raw)
In-Reply-To: <20130827122907.17435.24292.malonedeb@gac.canonical.com>

On 08/27/13 14:29, Lasse wrote:
> Public bug reported:
> 
> When qemu receives SIGQUIT, it should first try to run system_powerdown
> (giving the guest an ACPI signal to begin the shutdown process), before
> ending the whole qemu process.

I strongly disagree. SIGQUIT is an interactive debugging signal. It is
there so that the user running qemu can trigger a core dump from the
terminal, when he/she notices a problem.

http://www.gnu.org/software/libc/manual/html_node/Termination-Signals.html#index-SIGQUIT-2854

> At this point there is no way to do a graceful shutdown if you do not
> have access to the monitor and you do not use any wrapper like libvirt.
> 
> If, for some reason SIGQUIT would not be accepted as the signal, take
> any free to use signal, like SIGUSR1. There should be a way to get ACPI
> shutdown sent to the guest.

What's wrong with SIGINT / SIGTERM? Those signals are there to request a
clean shutdown (from the terminal and from an unrelated process,
respectively).

As far as I can see, both SIGINT and SIGTERM end up in
qemu_system_shutdown_request() on POSIX:

termsig_handler() [os-posix.c]
  qemu_system_killed() [vl.c]
    qemu_system_shutdown_request()

Laszlo