Hi, Paolo && Stefan: When I test the dataplane feature with git master, I find that VM will hang if dataplane is enabled. But if I use qemu-1.4.0, VM can start normally.
The command I boot QEMU is: x86_64-softmmu/qemu-system-x86_64 -enable-kvm -m 1024 -smp 2 -drive file=centos-6.4.raw,if=none,id=drive-virtio-disk,format=raw,cache=none,aio=native -device virtio-blk-pci,config-wce=off,scsi=off,x-data-plane=on,drive=drive-virtio-disk,id=virtio-disk git bisect implicates this bug was introduced by following commit: commit 82959e8262df7da882d715f8a0cb4e8c7cd6e94b Author: Paolo Bonzini <pbonz...@redhat.com> Date: Fri Feb 22 10:40:34 2013 +0100 dataplane: remove EventPoll in favor of AioContext During the review of the dataplane code, the EventPoll API morphed itself (not concidentially) into something very very similar to an AioContext. Thus, it is trivial to convert virtio-blk-dataplane to use AioContext, and a first baby step towards letting dataplane talk directly to the QEMU block layer. The only interesting note is the value-copy of EventNotifiers. At least in my opinion this is part of the EventNotifier API and is even portable to Windows. Of course, in this case you should not close the notifier's underlying file descriptors or handle with event_notifier_cleanup. Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com> I can provide more information if need. -- Best Regards, Dunrong Huang