Subject: Qemu hang introduced between next-20141013 and next-20141017

From: Martin Kelly <[email-masked]>
Date: Mon, 20 Oct 2014 20:14:37 -0700

Hi,

I have a minimal qemu setup that I used for testing development kernels.
I have noticed that somewhere between next-20141013 and next-20141017,
qemu started to hang at boot time, with no messages displayed on the console
(previously, it would boot to a full userspace). I attempted to bisect
it, but the next tree has so many merges that git bisect takes a very
long time. I have attached the config I'm using and have pasted the qemu
command below. The image I'm using is a minimal Wheezy image created
with debootstrap.

qemu command-line:
qemu-system-x86_64 -kernel arch/x86_64/boot/bzImage \
                   -smp 1 \
                   -drive file=wheezy.img,if=virtio \
                   -append 'root=/dev/vda console=hvc0' \
                   -chardev stdio,id=stdio,mux=on,signal=off \
                   -device virtio-serial-pci \
                   -device virtconsole,chardev=stdio \
                   -mon chardev=stdio \
                   -display none

Any idea what may have caused this or suggestions for debugging it?

Thanks,
Martin