Re: [Qemu-devel] [PATCH 3/4] virtio-console: Add support for multiple ports for generic guest-host communication

[Gerd Hoffmann <kraxel@redhat.com>]

On 09/23/09 13:50, Amit Shah wrote:
>> VirtConPortConsole (doesn't exist right now it seems ...).
>
> You're actually suggesting to split everything -- a console (in the
> current sense) is a different device and a port (the new vmchannels) are
> different devices. Right?

Yes, you'll have two devices.

#1 virtio-console which handles all virtio and is the master of
    the portbus.
#2 VirtChanPortConsole, which links the port and the chardev.

With this in place you'll have the current virtio-console functionality. 
  And on top you can create multiple console ports.

Then we can go enhance things and add more port drivers:

#3: One driver which allows external users (i.e. libguestfs) by linking
     a chardev too and attach a name tag.  That one can probably share
     all code except the init function with the console port driver.
#4: the watchdog.
#5: the vnc clipboard bits.
#6: whatever else we might find useful.

Ignoring backward-compatibility for now things should go like this:

-device virtio-console
    Creates the portbus master.  No ports (yet).

-device vmport-console,chardev=$dev
    Creates a port named 'org.qemu.console' and links it to $dev.

-device vmport-channel,chardev=$dev,name=$name
    Creates a port named $name, links it to $dev, for libguestfs and
    other external users.

-device vmport-watchdog
    Creates a port named 'org.qemu.watchdog', start timer when the guest
    openes the device, restart the watchdog timer each time the guest
    writes something, trigger watchdog action when the timer expires.
    Note: No chardev needed here.

-device vmport-clipboard
    vnc clipboard stuff goes here.  Probably needs no chardev too.


For backward-compatibility we'll allways have to create a vmport-console 
at port 0, so there will never be a virtio-console without a port.  That 
is a minor bit we can fixup once the above works fine.


cheers,
   Gerd