Re: [Qemu-devel] Re: virtio-serial: An interface for host-guest communication

[Amit Shah]

On (Thu) Aug 20 2009 [15:25:09], Daniel P. Berrange wrote:
> On Thu, Aug 20, 2009 at 07:12:41PM +0530, Amit Shah wrote:
> > 
> > I've now seen some more code here and to me it looks like virtioconsole
> > is not used on any of the guests that qemu supports. The virtio_console
> > kernel module only works with lguest and s390 currently. There is one
> > feature and some config values supported by the kernel module but not in
> > qemu.
> > 
> > So it looks as if we have virtio-console merged but no one uses it. Is
> > this right?
> 
> Nope. Grab a Fedora 11 live CD, and boot with
> 
>   # qemu-kvm -virtioconsole stdio -cdrom Fedora-11-i686-Live.iso  -m 500
> 
> Once it completes booting & logs into gnome, open a terminal and run
> as root
> 
>    agetty /dev/hvc0 9600 vt100  
> 
> You'll get a login prompt on the host machine now.
> 
> What appears to not be working, is early kernel boot messages. eg, I
> ought to be able todo

Oh; ok. So the console device is exposed only in the userspace; it's not
used for the early boot messages and not registered early-on. That's
only done for lguest and s390.

>   # qemu-kvm -virtioconsole stdio -kernel vmlinuz -initrd initrd.img \
>       -append "console=hvc0"  -m 500
> 
> and see the kernel boot messages, but this doesn't work with Fedora
> kernels at least. Not tried upstream, or looked to see if this is just
> an oversight in the Kconfig use for Fedora kernels.

Thanks,

                Amit