[Qemu-devel] Re: [PATCH 2/2] virtio-console: Notify resize to the guest.

[Amit Shah <amit.shah@redhat.com>]

On (Mon) May 03 2010 [12:06:33], Amit Shah wrote:
> From: Kusanagi Kouichi <slash@ac.auone-net.jp>
> 
> I tested this patch as follows: I put printf()s into involved
> functions. Then ran qemu on a terminal emulator, and resized it. The
> guest kernel gets initial size, and follows host resize. Both singleport
> and multiport work.
> 
> Signed-off-by: Kusanagi Kouichi <slash@ac.auone-net.jp>
> Signed-off-by: Amit Shah <amit.shah@redhat.com>
> ---
>  hw/virtio-console.c    |    3 +++
>  hw/virtio-serial-bus.c |   15 +++++++++++++++
>  hw/virtio-serial.h     |   11 +++++++++--
>  3 files changed, 27 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/virtio-console.c b/hw/virtio-console.c
> index caea11f..58246d1 100644
> --- a/hw/virtio-console.c
> +++ b/hw/virtio-console.c
> @@ -55,6 +55,9 @@ static void chr_event(void *opaque, int event)
>      case CHR_EVENT_CLOSED:
>          virtio_serial_close(&vcon->port);
>          break;
> +    case CHR_EVENT_RESIZE:
> +        virtio_serial_resize_console(&vcon->port, vcon->chr->rows, vcon->chr->cols);
> +        break;
>      }
>  }
>  
> diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c
> index 97694d5..8766f1d 100644
> --- a/hw/virtio-serial-bus.c
> +++ b/hw/virtio-serial-bus.c
> @@ -205,6 +205,20 @@ int virtio_serial_close(VirtIOSerialPort *port)
>      return 0;
>  }
>  
> +void virtio_serial_resize_console(VirtIOSerialPort *port, int rows, int cols)
> +{
> +    VirtIOSerial *vser = port->vser;
> +
> +    vser->config.rows = rows;
> +    vser->config.cols = cols;
> +
> +    if (use_multiport(vser)) {
> +        send_control_event(port, VIRTIO_CONSOLE_RESIZE, 0);

Thinking about this, this isn't the right way of sending console resize
updates: we write in the config space and send an update event via
control messages. The control message could be processed after another
config-space update for another port, leading to races.

I think it's better to send the row and column sizes along with the
resize message. We do something similar for sending the 'name'; we could
also imbed a struct within the VIRTIO_CONSOLE_RESIZE message similarly.
This would need some guest kernel changes too.

Kusanagi, can you do it? For guest kernel changes, please work off
linux-next.git for your changes.

If not, I'll get to this in a couple of weeks' time.

Thanks,

		Amit