[Spice-devel] Read data out of the Virtqueue

[Alon Levy]

On Thu, Mar 29, 2012 at 09:42:32AM +0000, Charles.Tsai-蔡清海-研究發展部 wrote:
> Alon,
> 
> Forget my previous mail. When I dig into the vdservice, I found there was one bug to check the overlay I/O status after calling the VirtIO write function.
> After I fixed the bug, I can see more printing raw data inside the Qemu now. Although I still find some issues, hopefully I can fix it as I debug more codes in both spice client and spice server. Thank you for your time.

Great that you managed to progress. Can you send a patch for the
vdservice issue? Is it a bug in the original or just in the one you
modified for printer channel?

> 
> -----Original Message-----
> From: Charles.Tsai-蔡清海-研究發展部 
> Sent: Wednesday, March 28, 2012 6:07 PM
> To: 'Alon Levy'
> Cc: spice-devel at lists.freedesktop.org
> Subject: Read data out of the Virtqueue
> 
> Alon,
> 
> My printer driver can write the printing raw data into virtIO driver. But I cannot see the found the printing raw data in the spice server. For the vdagent, I found the following code segment which is a callback to read the data from the vdi_port. Do I need to add a similar code to read the data from the Virtio?
> 
> In Qemu, I do see vmc_write is called when the printer driver writes the printing raw data into the  virtIOdevice.
> Consequently, function "spicevmc_red_channel_send_item" should be called to send the payload to the spice client. But I did not see function "spicevmc_red_channel_send_item" is called either. It looks like the printing rawa data is still inside the VirtIO queue. What function I need to add so as to pull the data out of the VirtIO queue?
> 
> =======================================================================================
> struct SpiceCharDeviceState vdagent_char_device_state = {
>     .wakeup = &vdagent_char_device_wakeup, };
> 
> 
> void vdagent_char_device_wakeup(SpiceCharDeviceInstance *sin) {
>     while (read_from_vdi_port());
> }