Re: [Xen-devel] [PATCH] Log qemu-dm's message with date, time and pid

[Yuji Shimada <shimada-yxb@xxxxxxxxxxxxxxx>]

I agree with developing proper logging functions. But without these
functions, I think ioemu-logger is a good solution.

We can reboot xend by the following command.
  # /etc/init.d/xend restart
Running of guest domains must not be affected by rebooting xend.

I'm sure that ioemu-logger dying is rare case. But there is no guarantee
that it doesn't die.
If xend starts ioemu-logger, xend loses one end of a pipe by rebooting
xend. After that, xend can't associates stdin for ioemu-logger with the
pipe when xend restarts ioemu-logger after ioemu-logger dies. This
problem happens because the life cycle of xend and qemu-dm is different.
So I think to start ioemu-logger by qemu-dm is more simple.

Using named pipe (FIFO), it's possible to start ioemu-logger by xend.
But sorry, I don't know about python well. Could anyone develope it?

Thanks.

--
Yuji Shimada

On Fri, 27 Jun 2008 14:40:58 +0100
Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx> wrote:

> Kevin Wolf writes ("Re: [Xen-devel] [PATCH] Log qemu-dm's message with date, 
> time and pid"):
> > Or maybe as another option, introduce proper logging functions instead
> > of fprintf on stderr into (upstream) qemu. This would be the most work,
> > of course, but IMHO also the cleanest solution.
> 
> Quite so.
> 
> > > I think that my implementation is more safety way because of the
> > > following reason.
> > > 
> > >   qemu-dm can easily restart ioemu-logger when ioemu-logger die.
> > >   And ioemu-logger death doesn't affected to guest software.
> > 
> > ioemu-logger is so simple that it would be a shame to see it crash anyway.
> 
> I don't think there is any significant risk of xend dying because it
> can't write one of these logs.  xend does lots of logging already of
> course.
> 
> Ian.


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