Re: raw disks no longer work in latest kvm (kvm-88 was fine)

[Antoine Martin <antoine@nagafix.co.uk>]

[snip]
>
> So there is something else at play. And just for the record:
> 1) kvm-88 works fine *with the exact same setup*
> 2) I've tried running as root
> 3) The raw disk mounts fine from the host.
> So I *know* the problem is with kvm. I wouldn't post to the list 
> without triple checking that.
>
> I have also just tested with another raw partition which is much 
> smaller (1GB) and the same thing still occurs: kvm-88 works and 
> qemu-kvm-0.12.3 does not.
> So I think that it is fair to assume that this new problem is 
> unrelated to the partition size.
I have narrowed it down to the "io-thread" option:
* rebuilding older versions of qemu without "--enable-io-thread" causes 
the bug (guest cannot open raw partition)
* qemu-kvm-0.12.3 cannot be built with "--enable-io-thread" over here:
   LINK  x86_64-softmmu/qemu-system-x86_64
kvm-all.o: In function `qemu_mutex_lock_iothread':
/usr/src/KVM/qemu-kvm-0.12.3/qemu-kvm.c:2532: multiple definition of 
`qemu_mutex_lock_iothread'
vl.o:/usr/src/KVM/qemu-kvm-0.12.3/vl.c:3772: first defined here
[..]
Which I have reported as part of another unsolved issue here:
http://www.mail-archive.com/kvm@vger.kernel.org/msg27663.html

Why not using the io-thread would prevent qemu from opening the raw 
partition is beyond me.

Antoine