Re: [Qemu-devel] [PATCH v5 6/8] hmat acpi: Build Memory Subsystem Address Range Structure(s) in ACPI HMAT

[Tao Xu <tao3.xu@intel.com>]

On 7/1/2019 7:25 PM, Igor Mammedov wrote:
> On Fri, 14 Jun 2019 23:56:24 +0800
> Tao Xu <tao3.xu@intel.com> wrote:
> 
...
>> @@ -2710,6 +2711,8 @@ void acpi_build(AcpiBuildTables *tables, MachineState *machine)
>>               acpi_add_table(table_offsets, tables_blob);
>>               build_slit(tables_blob, tables->linker, machine);
>>           }
>> +        acpi_add_table(table_offsets, tables_blob);
>> +        build_hmat(tables_blob, tables->linker, machine);
> I'm not sure if we should add it unconditionally.
> Is this table used in any meaningful manner by guest when
> it's incomplete (i.e. populated only with SPA records)?
> 
Hi Igor,

In ACPI 6.2, the linux kernel use it to show the memory ranges' 
node-id(Proximity Domain). In ACPI 6.3, the linux kernel use it to show 
the numa node's closest initiator(Generic Initiator or Processor, directly
attached). It is useful for a memory only numa node, because with 
SPA(renamed as "Memory Proximity Domain Attributes Structure" in ACPI 
6.3) the user-space can know the topology of hardware heterogeneous 
memory. I think I should add a doc to describe the use case in QEMU.

Therefore, the numa CLI may be lack of a input which can indicate the 
Initiator of a memory only numa node. Dan suggested me to add a new 
parameter for that[1].

Maybe like:
-numa node,mem=4G,nodeid=2,initiator=0

[1] https://patchwork.kernel.org/cover/10934417/

Thanks

Tao