[libvirt] [PATCH] conf: Allow omitting of numa node memory size

[Peter Krempa]

On Tue, Feb 21, 2017 at 15:36:23 +0000, Daniel Berrange wrote:
> On Tue, Feb 21, 2017 at 04:22:05PM +0100, Peter Krempa wrote:
> > Memory-less numa nodes could be specified by setting the memory size to
> > 0. Allow ommiting of the parameter completely to specify the same.
> > 
> > Partially resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1217144
> 
> Does this correctly plumb through to the guest OS ?
> 
> Last time we tried fixing this bug we found some problems - I can't remember
> whether the problem was with 0 CPUs or 0 memory, but with one of them, QEMU
> would totally mangle the NUMA topology, merging nodes together.

I tried it and indeed the NUMA topology for a memory-less node shows up
totally broken in the guest. From your comments on the linked bugzilla
I thought that it worked properly if you specify memory='0' explicitly.

Since cpu-less nodes are possible for a long time and with the new
cpu-hotplug API you can select individual vcpus to hotplug according to
the id I was under the impression that only the syntax-sugar stuff was
necessary to cover everyting.

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