Re: [Qemu-devel] NVDIMM live migration broken?

[Stefan Hajnoczi]

On Fri, Jun 23, 2017 at 08:13:13AM +0800, address@hidden wrote:
> On 06/22/17 15:08 +0100, Stefan Hajnoczi wrote:
> > I tried live migrating a guest with NVDIMM on qemu.git/master (edf8bc984):
> > 
> >   $ qemu -M accel=kvm,nvdimm=on -m 1G,slots=4,maxmem=8G -cpu host \
> >          -object 
> > memory-backend-file,id=mem1,share=on,mem-path=nvdimm.dat,size=1G \
> >      -device nvdimm,id=nvdimm1,memdev=mem1 \
> >      -drive if=virtio,file=test.img,format=raw
> > 
> >   $ qemu -M accel=kvm,nvdimm=on -m 1G,slots=4,maxmem=8G -cpu host \
> >          -object 
> > memory-backend-file,id=mem1,share=on,mem-path=nvdimm.dat,size=1G \
> >      -device nvdimm,id=nvdimm1,memdev=mem1 \
> >      -drive if=virtio,file=test.img,format=raw \
> >      -incoming tcp::1234
> > 
> >   (qemu) migrate tcp:127.0.0.1:1234
> > 
> > The guest kernel panics or hangs every time on the destination.  It
> > happens as long as the nvdimm device is present - I didn't even mount it
> > inside the guest.
> > 
> > Is migration expected to work?
> 
> Yes, I tested on QEMU 2.8.0 several months ago and it worked. I'll
> have a look at this issue.

Great, thanks!

David Gilbert suggested the following on IRC, it sounds like a good
starting point for debugging:

Launch the destination QEMU with -S (vcpus will be paused) and after
migration has completed, compare the NVDIMM contents on source and
destination.

Stefan

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