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Date: Wed, 3 Jul 2013 11:13:42 +0200
From: Stefan Hajnoczi <stefanha@gmail.com>
Message-ID: <20130703091342.GD17614@stefanha-thinkpad.muc.redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v5] Add timestamp to error_report()
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To: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: "kwolf@redhat.com" <kwolf@redhat.com>, "aliguori@us.ibm.com" <aliguori@us.ibm.com>, "mtosatti@redhat.com" <mtosatti@redhat.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, "armbru@redhat.com" <armbru@redhat.com>, "dle-develop@lists.sourceforge.net" <dle-develop@lists.sourceforge.net>, Tomoki Sekiyama <tomoki.sekiyama@hds.com>, "pbonzini@redhat.com" <pbonzini@redhat.com>, "lcapitulino@redhat.com" <lcapitulino@redhat.com>, "lersek@redhat.com" <lersek@redhat.com>

On Tue, Jul 02, 2013 at 02:09:24PM +0000, Seiji Aguchi wrote:
> 
> 
> > > +DEF("msg", HAS_ARG, QEMU_OPTION_msg,
> > > +    "-msg [timestamp=on|off]\n"
> > > +    "  change the format of messages\n"
> > > +    "  timestamp=on|off enables leading timestamps (default:on)\n",
> > > +    QEMU_ARCH_ALL)
> > > +STEXI
> > > +@item -msg timestamp=on|off
> > > +@findex -msg
> > > +prepend a timestamp to each log message.
> > > +(disabled by default)
> > > +ETEXI
> > 
> > I am confused.  If the user specifies -msg then enable_timestamp_msg is
> > on by default.  If the user does not specify -msg then
> > enable_timestmap_msg is off.  Did I get that right?
> 
> Yes.
> 
> > 
> > This means that the default behavior of QEMU does not change but you can
> > add -msg to enable timestamps.
> > 
> > I'm happy with this but find the documentation confusing.
> 
> I can remove "(disabled by default)" if needed.

Perhaps the simplest solution is timestamp=off by default.  Then there
can be no confusion and users must do -msg timestamp=on to enable
timestamps.

If you really want to keep -msg as a shortcut for -msg timestamp=on,
then please document explicitly that:
1. Without -msg timestamps are off.
1. With -msg timestamps are on.
2. -msg timestamp=off can be used to turn timestamps off again.

Stefan