Re: [Qemu-devel] virtio-blk broken after system reset

[Stefan Hajnoczi <stefanha@gmail.com>]

On Fri, Nov 12, 2010 at 10:02 PM, Jan Kiszka <jan.kiszka@web.de> wrote:
> Hi,
>
> both after hard and guest-initiated reset, something is seriously broken
> with virtio block devices. If I reset my Linux guest while still in
> grub, the bios will simply fail to read from the disk after the reboot. If I
> reset after Linux touched the device, qemu terminates:
>
> Breakpoint 1, 0x00007ffff4b945b0 in _exit () from /lib64/libc.so.6
> (gdb) bt
> #0  0x00007ffff4b945b0 in _exit () from /lib64/libc.so.6
> #1  0x00007ffff4b2948d in __run_exit_handlers () from /lib64/libc.so.6
> #2  0x00007ffff4b29535 in exit () from /lib64/libc.so.6
> #3  0x0000000000568da3 in virtqueue_num_heads (vq=0x17040e0, idx=0) at /data/qemu/hw/virtio.c:258
> #4  0x0000000000569511 in virtqueue_pop (vq=0x17040e0, elem=0x17cea58) at /data/qemu/hw/virtio.c:388
> #5  0x0000000000419e31 in virtio_blk_get_request (s=0x1704010) at /data/qemu/hw/virtio-blk.c:132
> #6  virtio_blk_handle_output (vdev=0x1704010, vq=<value optimized out>) at /data/qemu/hw/virtio-blk.c:369
>
> This is with current qemu.git head, haven't tried older versions. Known bug?

This is a known issue.  Gleb has posted a SeaBIOS fix:

http://www.mail-archive.com/qemu-devel@nongnu.org/msg45849.html

Currently the patch only appears in SeaBIOS master.  Gleb and Kevin
have discussed putting it into 0.6.1.2 stable (see linked thread).
QEMU should then pick that release up.

Stefan