Re: [Qemu-devel] [RFC PATCH v0] numa: API to lookup NUMA node by address

[Bharata B Rao <bharata@linux.vnet.ibm.com>]

On Thu, Jun 11, 2015 at 08:56:03AM +0200, Igor Mammedov wrote:
<snip>
> > > > And to make this work, it needs to be aware of NUMA information for
> > > > hotplugged memory too.
> > > I've checked spapr_populate_drconf_memory() from original series,
> > > it needs to be aware at startup about address ranges -> node mapping
> > > including mapping partitioning of whole hotplug memory range
> > > (i.e. not actual hotplugged memory).
> > > -numa node_mem  & numa_set_mem_node_id() are sufficient for this purpose 
> > 
> > spapr_populate_drconf_memory() needs to know about node information for
> > boot time memory as well as the hotplugged pc-dimm memory. Since chunks
> > of hotplug memory range could be plugged into any node, we need to
> > be able to locate the node id for such memory range. This is where
> > numa_set_mem_node_id() call for each realized dimm will help.
> So you are saying that spapr_populate_drconf_memory() doesn't need to know
> in advance about unplugged memory ranges and could be updated at runtime.
> (I've thought that device tree is build only at boot and guest can't
> accept dynamic updates to it, therefore you'd need provide addr -> node_id
> mapping at boot time including for not yet plugged memory).

Here are we dynamically adding a device tree node at runtime when guest
issues ibm,architecture-client-support call during early boot. Guest firmware
(SLOF) has already been updated to support such dynamic update.

During hotplug the node id information is also updated in
ibm,dynamic-memory property that is present under this device tree node.

Regards,
Bharata.