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

[Amit Shah]

On (Wed) Aug 05 2009 [18:57:13], Jamie Lokier wrote:
> Anthony Liguori wrote:
> > Richard W.M. Jones wrote:
> > Have you considered using a usb serial device?  Something attractive 
> > about it is that a productid/vendorid can be specified which means that 
> > you can use that as a method of enumerating devices.
> > 
> > Hot add/remove is supported automagically.
> 
> The same applies to PCI: productid/vendorid (and subids);
> PCI hotplug is possible though not as native as USB.
> 
> Here's another idea: Many devices these days have a serial number or
> id string.  E.g. USB storage, ATA drives, media cards, etc.  Linux
> these days creates alias device nodes which include the id string in
> the device name.  E.g. /dev/disks/by-id/ata-FUJITSU_MHV2100BH_NWAQT662615H
> 
> So in addition to (or instead of) /dev/vmch0, /dev/vmch1 etc.,
> Linux guests could easily generate:
> 
>     /dev/vmchannel/by-role/clipboard-0
>     /dev/vmchannel/by-role/gueststats-0
>     /dev/vmchannel/by-role/vmmanager-0

That's interesting; worth a thought. When we actually have all the
parties together (libvirt, libguestfs, qemu) to decide which ports need
to act as which transports, we'll be able to add this.

> It's not necessary to do this at the beginning.  All that is needed is
> to provide enough id information that will appear in /sys/..., so that
> that a udev policy for naming devices can be created at some later date.

True.

                Amit