Comment 24 for bug 818673

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Rick Vernam (rickv-hobi) wrote : Re: [Qemu-devel] [Bug 818673] Re: virtio: trying to map MMIO memory

On Thursday 15 September 2011 11:23:53 Rick Vernam wrote:
> On Wednesday 14 September 2011 16:30:11 Rick Vernam wrote:
> > On Wednesday 14 September 2011 14:42:09 vrozenfe wrote:
> > > Thank you, Rick.
> > >
> > > Could you help me to narrow this problem down?
> >
> > Absolutely.
> >
> > > As I see, you have three virtio drivers installed on your system -
> > > block, net, and virtio serial. Technically, anyone of them can create
> > > "trying to map MMIO memory" problem. The best way to find a buggy
> > > driver ( or drivers) will be to isolate one from the other. If you
> > > can, please try running only one virtio device every time to see which
> > > driver sends incorrect scatter/gather list element to QEMU.
> >
> > Sure, no problem. I'll have that in the next few days.
>
> I started qemu without any of the virt-serial stuff, specfically:
> qemu-system-x86_64 -cpu host -enable-kvm -pidfile
> /home/rick/qemu/hds/wxp.pid - drive
> file=/home/rick/qemu/hds/wxp.raw,if=virtio,aio=native -m 1536 -name WinXP
> -net nic,model=virtio -net user -localtime -usb -vga qxl -spice
> port=1234,disable-ticketing -monitor stdio
>
> It's been running for around 2 hours and no crash yet.
So without virt-serial, the machine ran until I rebooted the guest OS, then
crashed with the same error message. Without virt-serial it seemed to be
stable so long as it was just left running.

Now I'll run it without virt-net, and let you know how that goes.

>
> Thanks,
> -Rick
>
> > > Another question. You said, the problem happens after every second or
> > > third restart. Do you shutdown your VM, or just restart it?
> >
> > Have to shut down the VM guest so that the qemu process exits.
> >
> > > How does it work
> > > after going through several hibernate/resume, and/or suspend/resume
> > > cycles.
> >
> > I often will suspend with or without pausing qemu (via monitor commands
> > 'stop' and 'cont'). I have never experienced any problem with the qemu
> > process that was running prior to the suspend.
> >
> > > Best regards,
> > > Vadim.
> >
> > Thanks,
> > -Rik