[Qemu-devel] Re: Extending virtio_console to support multiple ports

[Anthony Liguori]

Amit Shah wrote:
> I did think about that as well, but there are problems:
>
> - vnc clients (at least tigervnc) wants to receive the entire clipboard
>   in a single flush command. So in the pre-allocated buffers scenario we
>   could run short of the available buffers in some cases. So there will
>   have to be a flag with each buffer that says 'there's more data
>   pending for this particular write' which will have to be passed on to
>   qemu and qemu will then flush it once it receives all the data
>   

No flags, assume it's a streaming protocol and don't assume anything 
about message sizes.  IOW, when you send clipboard data, send size and 
then the data.  QEMU consumes bytes until it reaches size.

> - A lock has to be introduced to fetch one unused buffer from the list
>   and pass it on to the host. And this lock has to be a spinlock, just
>   because writes can be called from irq context.
>   

I don't see a problem here.

Regards,

Anthony Liguori

>                 Amit
>