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

[Jamie Lokier <jamie@shareable.org>]

Gleb Natapov wrote:
> On Wed, Jul 29, 2009 at 01:14:18PM +0530, Amit Shah wrote:
> > But why do we want to limit the device to only one port? It's not too
> > complex supporting additional ones.
> > 
> > As I see it qemu and the kernel should provide the basic abstraction for
> > the userspace to go do its job. Why create unnecessary barriers?
> > 
> I agree. If userspace wants it may use only one channel and demultiplex
> messages by itself, but we shouldn't force it to. Also one of the
> requirements for virtio-serial is to have connect disconnect
> notifications. It is not possible with demultiplexing in the userspace.

I agree too, for all those reasons.

However it would be useful if the devices provided a simpler way to be
found by guest applications than /dev/vmch0, vmch1, vmch2...

On Linux udev provides a sane way to find devices according to roles,
subtypes, serial numbers, whatever you want, if the appropriate id
codes are available from the devices and put into /sys/* by the kernel
driver.  That would make the devices much more useful to independent
applications, imho.

-- Jamie