Re: [Qemu-devel] [PATCH] Support logging xen-guest console

[Ian Campbell]

On Mon, 2011-06-20 at 19:42 +0100, Stefano Stabellini wrote:
> > @@ -198,6 +248,10 @@ static int con_init(struct XenDevice *xendev)
> >      else
> >          con->chr = serial_hds[con->xendev.dev];
> >  
> > +    logenv = getenv("XENCONSOLED_TRACE");
> > +    if (logenv != NULL && !strcmp(logenv, "guest")) {
> > +        log_guest = 1;
> > +    }
> >      return 0;
> >  }
> 
> please check the length of logenv before using strcmp on it

surely getenv() isn't the correct interface anyway?

What guarantees that the environment running qemu will have
the /etc/sysconfig/xencommons derived settings in it? It's not usually
the case under xl unless the user happens to have sources the file
(which would be strange).

Also XENCONSOLED_TRACE is clearly a setting aimed at xenconsoled -- not
qemu. In fact it is really a setting for the xencommons initscript which
turns it into the appropriate xenconsoled command line option.

Perhaps we should be plumbing the console to xenconsoled (like we do for
serial = pty), that'll get us this logging for free and be consistent to
Xen users compared with PV guests, HVM serial=pty and similar...

The other option would be to properly plumb this stuff through the qemu
command line and make use of it from the Xen toolstack as necessary.

Ian.