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

[Amit Shah]

On (Wed) Sep 23 2009 [14:30:39], Gerd Hoffmann wrote:
> 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.

Right; This is in place now.

> #2 VirtChanPortConsole, which links the port and the chardev.

OK; So based on the last mail the port functionality could be split in a
separate file.

> 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.

Right; this model looks good. It wasn't obvious to me the first time you
mentioned it (I didn't think adding something like a VirtConPortVnc and
some init functions in vnc.c would make any sense -- but actually looks
like it would be cleaner to do that).

> 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.

OK; that's what I have now, slightly different:

-device virtio-console-pci -device virtconport,port=0,chardev=$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.

ie -virtioconsole <chardev> ?

I'd suggest we just drop that in 0.12.

                Amit