Re: [Qemu-devel] [bisected] VNC server can't get all sent chars correctly

[Gonglei (Arei)]

> From: Markus Armbruster [mailto:address@hidden
> Sent: Monday, August 25, 2014 3:30 PM
> To: Michael Tokarev
> Cc: qemu-devel; Gonglei (Arei); Gabriele Giacone; Gerd Hoffmann;
> address@hidden
> Subject: Re: [Qemu-devel] [bisected] VNC server can't get all sent chars
> correctly
> 
> Michael Tokarev <address@hidden> writes:
> 
> > There's a bug filed against debian qemu package, there:
> >
> >  http://bugs.debian.org/758881
> >
> > which says about problems sending keypress events over VNC to
> > a qemu guest, -- some keypresses gets lost, at least.
> >
> > The bisection between qemu 2.0 and 2.1 leads to this commit:
> >
> > commit 2858ab09e6f708e381fc1a1cc87e747a690c4884
> > Author: Gonglei <address@hidden>
> > Date:   Thu Apr 24 20:06:19 2014 +0800
> >
> >     ps2: set ps/2 output buffer size as the same as kernel
> >
> >     According to the PS/2 Mouse/Keyboard Protocol, the keyboard outupt
> buffer size
> >     is 16 bytes. And the PS2_QUEUE_SIZE 256 was introduced in Qemu from
> the very
> >     beginning.
> >
> >     When I started a  redhat5.6 32bit guest, meanwhile tapped the
> keyboard as quickly as
> >     possible, the screen would show me "i8042.c: No controller found". As a
> result,
> >     I couldn't use the keyboard in the VNC client.
> >
> >     Previous discussion about the issue in maillist:
> >
> http://thread.gmane.org/gmane.comp.emulators.qemu/43294/focus=47180
> >
> >     This patch has been tested on redhat5.6 32-bit/suse11sp3 64-bit
> guests.
> >     More easy meathod to reproduce:
> >     1.boot a guest with libvirt.
> >     2.connect to VNC client.
> >     3.as you see the BIOS, bootloader, Linux booting, run the follow simply
> shell script:
> >     for((i=0;i<10000000;i++)) do virsh send-key redhat5.6 KEY_A; done
> >
> >     Actual results:
> >     dmesg show "i8042.c: No controller found." And the keyboard is out of
> work.
> >
> >     Signed-off-by: Gonglei <address@hidden>
> >     Reviewed-by: Juan Quintela <address@hidden>
> >     Signed-off-by: Gerd Hoffmann <address@hidden>
> >
> >
> > So it looks like something else is not right here.  Before this patch,
> > it wasn't possible to use keyboard with VNC client with redhat 5 guest.
> > Now, it isn't possible to use keyboard with VNC in another scenario which
> > worked before (so it is a regression compared with 2.0 version).
> >
> > What do we do with this? :)
> 
> Suggest to add a tracepoint to the place that drops keystrokes due to
> buffer being full, to verify that's really what happens.  Quick glance
> at the code suggests ps2_queue().

+1  :)

Best regards,
-Gonglei