Re: [Qemu-devel] Unable to add ram object with same ID after addition, migration and removal at the target

[David Gibson]

On Mon, Dec 05, 2016 at 12:44:53AM -0600, Michael Roth wrote:
> Quoting Bharata B Rao (2016-12-04 21:51:32)
> > On Fri, Dec 2, 2016 at 11:46 PM, Dr. David Alan Gilbert <address@hidden>
> > wrote:
> > 
> >     * Bharata B Rao (address@hidden) wrote:
> >     > Hi,
> >     >
> >     > - Add ram object and dimm device at the source
> >     >
> >     > (qemu) object_add memory-backend-ram,id=ram0,size=128M
> >     > (qemu) device_add pc-dimm,id=dimm0,memdev=ram0
> >     >
> >     > - Migrate the VM and remove the dimm device and ram object at the 
> > target
> >     >
> >     > (qemu) device_del dimm0
> >     > (qemu) object_del ram0
> >     >
> >     > - Adding the ram object with same id now at the target fails like 
> > this:
> >     >
> >     > (qemu) info memdev
> >     >
> >     > (qemu) object_add memory-backend-ram,id=ram0,size=128M
> >     > Duplicate ID 'ram0' for object
> >     >
> >     > Same behaviour is seen on x86 and Power. The problem isn't seen if
> >     > migration isn't involved (add, remove, add at the source itself).
> > 
> >     Is this the same as the one Michael Roth posted a fix for a few days
> >     back; 'monitor: fix object_del for command-line-created objects'
> > 
> >     https://lists.gnu.org/archive/html/qemu-devel/2016-11/msg05479.html
> > 
> > 
> > Yes, this is same as above, I hadn't noticed Michael's fix.
> > 
> > Will be good to have this fix in 2.8.
> 
> I considered shooting for 2.8, but since it's only triggerable with HMP
> (QMP doesn't use the QemuOpts-based parsing so it doesn't hit the
> duplicate ID error, so libvirt in turn would be uneffected), and doesn't
> seem to be a regression (AFAICT it's been an issue since object_del was
> introduced), I figured it could wait till 2.9/2.8.1.
> 
> Definitely a pain for testing though...

How complex is the fix?  If it's simple, then AIUI we can still put
real bugfixes like this into 2.8.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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