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+instruction: 0.768
+device: 0.764
+other: 0.737
+graphic: 0.723
+semantic: 0.669
+vnc: 0.656
+socket: 0.652
+mistranslation: 0.652
+boot: 0.637
+assembly: 0.623
+network: 0.606
+KVM: 0.601
+
+[Qemu-devel] Can I have someone's feedback on [bug 1809075] Concurrency bug on keyboard events: capslock LED messing up keycode streams causes character misses at guest kernel
+
+Hi everyone.
+Can I please have someone's feedback on this bug?
+https://bugs.launchpad.net/qemu/+bug/1809075
+Briefly, guest OS loses characters sent to it via vnc. And I spot the
+bug in relation to ps2 driver.
+I'm thinking of possible fixes and I might want to use a memory barrier.
+But I would really like to have some suggestion from a qemu developer
+first. For example, can we brutally drop capslock LED key events in ps2
+queue?
+It is actually relevant to openQA, an automated QA tool for openSUSE.
+And this bug blocks a few test cases for us.
+Thank you in advance!
+
+Kind regards,
+Gao Zhiyuan
+
+Cc'ing Marc-André & Gerd.
+
+On 12/19/18 10:31 AM, Gao Zhiyuan wrote:
+>
+Hi everyone.
+>
+>
+Can I please have someone's feedback on this bug?
+>
+https://bugs.launchpad.net/qemu/+bug/1809075
+>
+Briefly, guest OS loses characters sent to it via vnc. And I spot the
+>
+bug in relation to ps2 driver.
+>
+>
+I'm thinking of possible fixes and I might want to use a memory barrier.
+>
+But I would really like to have some suggestion from a qemu developer
+>
+first. For example, can we brutally drop capslock LED key events in ps2
+>
+queue?
+>
+>
+It is actually relevant to openQA, an automated QA tool for openSUSE.
+>
+And this bug blocks a few test cases for us.
+>
+>
+Thank you in advance!
+>
+>
+Kind regards,
+>
+Gao Zhiyuan
+>
+
+On Thu, Jan 03, 2019 at 12:05:54PM +0100, Philippe Mathieu-Daudé wrote:
+>
+Cc'ing Marc-André & Gerd.
+>
+>
+On 12/19/18 10:31 AM, Gao Zhiyuan wrote:
+>
+> Hi everyone.
+>
+>
+>
+> Can I please have someone's feedback on this bug?
+>
+>
+https://bugs.launchpad.net/qemu/+bug/1809075
+>
+> Briefly, guest OS loses characters sent to it via vnc. And I spot the
+>
+> bug in relation to ps2 driver.
+>
+>
+>
+> I'm thinking of possible fixes and I might want to use a memory barrier.
+>
+> But I would really like to have some suggestion from a qemu developer
+>
+> first. For example, can we brutally drop capslock LED key events in ps2
+>
+> queue?
+There is no "capslock LED key event".  0xfa is KBD_REPLY_ACK, and the
+device queues it in response to guest port writes.  Yes, the ack can
+race with actual key events.  But IMO that isn't a bug in qemu.
+
+Probably the linux kernel just throws away everything until it got the
+ack for the port write, and that way the key event gets lost.  On
+physical hardware you will not notice because it is next to impossible
+to type fast enough to hit the race window.
+
+So, go fix the kernel.
+
+Alternatively fix vncdotool to send uppercase letters properly with
+shift key pressed.  Then qemu wouldn't generate capslock key events
+(that happens because qemu thinks guest and host capslock state is out
+of sync) and the guests's capslock led update request wouldn't get into
+the way.
+
+cheers,
+  Gerd
+