Re: [Qemu-devel] [PATCH] x86/acpi: build SRAT when memory hotplug is enabled

[Igor Mammedov <imammedo@redhat.com>]

On Tue, 5 Sep 2017 09:17:06 +0800
Dou Liyang <douly.fnst@cn.fujitsu.com> wrote:

> Hi Eduardo,
> 
> At 09/04/2017 09:08 PM, Eduardo Habkost wrote:
> [...]
> >> In my opinion, this may also add the hotpluggable memory, and see the
> >> following commemts.
> >>
> >>     /*
> >>      * Entry is required for Windows to enable memory hotplug in OS
> >>      * and for Linux to enable SWIOTLB when booted with less than
> >>            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >>      * 4G of RAM. Windows works better if the entry sets proximity
> >>      * to the highest NUMA node in the machine.
> >>      * Memory devices may override proximity set by this entry,
> >>      * providing _PXM method if necessary.
> >>      */
> >>     if (hotplugabble_address_space_size) {
> >>         numamem = acpi_data_push(table_data, sizeof *numamem);
> >>         build_srat_memory(numamem, pcms->hotplug_memory.base,
> >>                           hotplugabble_address_space_size, pcms->numa_nodes
> >> - 1,
> >>                           MEM_AFFINITY_HOTPLUGGABLE | MEM_AFFINITY_ENABLED);
> >>     }  
> >
> > You are correct, I didn't see that part of the code.  If that's
> > the entry that's missing, the patch makes sense.  Thanks!
> >
> > However, the resulting tables still don't look correct: it will
> > generate an entry assigned to NUMA node (uint32_t)-1 if no NUMA
> > nodes are configured elsewhere, some APIC entries, but no entries
> > for the rest of the memory.  
> 
> Yes, indeed.
> 
> >
> > Igor's suggestion to enable NUMA implicitly sounds safer to me.
> >  
> 
> I agree with Igor too.
> 
> Is anybody doing this? If not, may I make a patch to enable adding NUMA
> node implicitly first. let's see what it looks like.
As far as I'm aware nobody is doing it, so fill free to look into it.

> 
> Thanks,
> 	dou.
> 
>