Migration issue with hot-added dimm

[xdel]

Seems that after dimm hot-add migration is impossible:

Initial configuration follows

  <qemu:commandline>
    <qemu:arg value='-device'/>
    <qemu:arg value='dimm,id=dimm0,size=256M,node=0,populated=on,bus=membus.0'/>
    <qemu:arg value='-device'/>
    <qemu:arg value='dimm,id=dimm1,size=256M,node=0,populated=off,bus=membus.0'/>
    <qemu:arg value='-device'/>
    <qemu:arg value='dimm,id=dimm2,size=256M,node=0,populated=off,bus=membus.0'/>
    <qemu:arg value='-device'/>
    <qemu:arg value='dimm,id=dimm3,size=256M,node=0,populated=off,bus=membus.0'/>
    <qemu:arg value='-device'/>
    <qemu:arg value='dimm,id=dimm4,size=256M,node=0,populated=off,bus=membus.0'/>
    <qemu:arg value='-device'/>
    <qemu:arg value='dimm,id=dimm5,size=256M,node=0,populated=off,bus=membus.0'/>
    <qemu:arg value='-device'/>
    <qemu:arg value='dimm,id=dimm6,size=256M,node=0,populated=off,bus=membus.0'/>
  </qemu:commandline>

and migration works just fine. After executing

qemu-monitor-command --hmp vm010-000-001-005 device_add dimm,id=dimm1,populated=on,bus=membus.0

migration doesn`t work anymore:

Unknown ramblock "dimm1", cannot accept migration
qemu: warning: error while loading state for instance 0x0 of device 'ram'
load of migration failed

This happens on memhpv4 4a80517

[vliaskov]

thanks for testing. This issue is known and there was a patch in memhp-v3 to solve it. But it's a bit of a hack and was removed temporarily from v4.

Please try to apply commit 55833af (HEAD of memhp-v4-fixes branch called "fix live-migration when "populated=on" is missing") and let me know if it fixes the problem for you.

[vliaskov]

Note 55833af may not apply cleanly to memhpv4 (memhp-v4-fixes has a slightly different header file because it updated "piix_pci and pc_piix: refactor " slightly). But it should be easy to solve. Or you could checkout memhp-v4-fixes

[xdel]

Unfortunately this fix does not help me, problem still persists with same error message.

[xdel]

By the way, piix_pci.h still missing from the current tree, which prevents proper testing by most of people, can you please add it?

[vliaskov]

ok, the header file was added with a separate commit on memhpv-4 HEAD.

I haven't fixed the migration issue yet, I 'll update when I have something.I assume the dimm configuration (command line) you are using on source and destination side is the same.