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Date: Thu, 29 Dec 2011 19:56:58 +0530
From: Amit Shah <amit.shah@redhat.com>
Message-ID: <20111229142658.GD4576@amit.redhat.com>
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Subject: Re: [Qemu-devel] [PATCHv2] Fix virtio-console failure on
	unconnected pty
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To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, Alexander Graf <agraf@suse.de>

On (Thu) 29 Dec 2011 [15:16:55], Christian Borntraeger wrote:
> >> +++ b/hw/virtio-serial-bus.c
> >> @@ -163,7 +163,19 @@ static void do_flush_queued_data(VirtIOS
> >>                  abort();
> >>              }
> >>              if (ret == -EAGAIN || (ret >= 0 && ret < buf_size)) {
> >> -                virtio_serial_throttle_port(port, true);
> > 
> > I'm surprised: did you test this with upstream qemu?  That codebase
> > doesn't yet throttle writes, and this code path won't execute.  Does
> > it really not reproduce with this patch?
> 
> I think 
> static void handle_output(VirtIODevice *vdev, VirtQueue *vq)
> [....]
>     if (!port->throttled) {
>         do_flush_queued_data(port, vq, vdev);
>         return;
> 
> makes a difference here, since we will never return the buffer to the guest, no?

port->throttled never becomes true for qemu.  I'm just unsure how this
patch works for you :)

		Amit