[SeaBIOS] Intermittent USB keyboard freeze

[Gabriel L. Somlo]

Hi Kevin,

I'm running into an intermittent (roughly 50% of the time) USB
keyboard freeze, using the following command line:

bin/qemu-system-x86_64 -enable-kvm -m 2048 -cpu core2duo -M q35 \
  -usb -device usb-kbd -device usb-mouse \
  -device ide-drive,bus=ide.2,drive=HDD \
  -drive id=HDD,if=none,snapshot=on,file=./Fedora-Live-Desktop-x86_64-20-1.iso \
  -bios bios-test.bin

where both qemu and bios-test.bin are built from their latest currently
available git masters.

The symptom is that, roughly half the time I can't navigate the grub
splash screen to select an entry via the up/down arrow keys. After a
few keystrokes, I start getting console errors like this:

usb-kbd: warning: key event queue full
usb-kbd: warning: key event queue full
usb-kbd: warning: key event queue full
...

It's not specific to grub/Fedora either, I get the same behavior with
Chameleon when trying to boot OS X.

The other 50% of the time, things work just fine.


After a bisect on Seabios, I *think* the culprit is commit
4ea2fa9620ec4c0c6da53d534d6a69c8a0db27cd


I couldn't easily reverse that patch due to other churn in the code,
so I wasn't able to build a seabios with everything but that commit
to test for sure.

Also, one has to fire up qemu several (at least 10) times to
adequately make sure the problem isn't present, so take my bisect with
a grain of salt in case the content of the patch doesn't make sense
with respect to the error behavior :)

Thanks,
--Gabriel