On 2025/4/23 20:41, Michael S. Tsirkin wrote:
> On Wed, Apr 23, 2025 at 12:41:28PM +0100, Alireza Sanaee wrote:
>> From: Yicong Yang <yangyic...@hisilicon.com>
>>
>> Currently we build the PPTT starting from the socket node and each
>> socket will be a separate tree. For a multi-socket system it'll
>> be hard for the OS to know the whole system is homogeneous or not
>> (actually we're in the current implementation) since no parent node
>> to telling the identical implementation informentation. Add a
>> root node for indicating this.
>>
>> Signed-off-by: Yicong Yang <yangyic...@hisilicon.com>
>> Reviewed-by: Jonathan Cameron <jonathan.came...@huawei.com>
>> Signed-off-by: Alireza Sanaee <alireza.san...@huawei.com>
>
> so how does the topology look before and after this change?
>
for a 2 socket system, the PPTT processor hierarchy tree before this change
will be like:
[Socket 0] [Socket 1]
^ ^
|-----------\ |-----------\
[CPU 0] ... [CPU 1] [CPU 0] ... [CPU 1]
after this change there will be a root node in the tree:
[Root Node]
^
|-------------------\
[Socket 0] [Socket 1]
^ ^
|-----------\ |-----------\
[CPU 0] ... [CPU 1] [CPU 0] ... [CPU 1]
>
>> ---
>> hw/acpi/aml-build.c | 15 ++++++++++++++-
>> 1 file changed, 14 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
>> index 560cee12a24b..3010325ca423 100644
>> --- a/hw/acpi/aml-build.c
>> +++ b/hw/acpi/aml-build.c
>> @@ -2153,12 +2153,25 @@ void build_pptt(GArray *table_data, BIOSLinker
>> *linker, MachineState *ms,
>> int64_t socket_id = -1, cluster_id = -1, core_id = -1;
>> uint32_t socket_offset = 0, cluster_offset = 0, core_offset = 0;
>> uint32_t pptt_start = table_data->len;
>> + uint32_t root_offset;
>> int n;
>> AcpiTable table = { .sig = "PPTT", .rev = 2,
>> .oem_id = oem_id, .oem_table_id = oem_table_id };
>>
>> acpi_table_begin(&table, table_data);
>>
>> + /*
>> + * Build a root node for all the processor nodes. Otherwise when
>> + * building a multi-socket system each socket tree are separated
>
> is separated?
>
>> + * and will be hard for the OS like Linux to know whether the
>> + * system is homogeneous.
>> + */
>> + root_offset = table_data->len - pptt_start;
>> + build_processor_hierarchy_node(table_data,
>> + (1 << 0) | /* Physical package */
>> + (1 << 4), /* Identical Implementation */
>> + 0, 0, NULL, 0);
>> +
>> /*
>> * This works with the assumption that cpus[n].props.*_id has been
>> * sorted from top to down levels in mc->possible_cpu_arch_ids().
>> @@ -2175,7 +2188,7 @@ void build_pptt(GArray *table_data, BIOSLinker
>> *linker, MachineState *ms,
>> build_processor_hierarchy_node(table_data,
>> (1 << 0) | /* Physical package */
>> (1 << 4), /* Identical Implementation */
>> - 0, socket_id, NULL, 0);
>> + root_offset, socket_id, NULL, 0);
>> }
>>
>> if (mc->smp_props.clusters_supported && mc->smp_props.has_clusters)
>> {
>> --
>> 2.34.1
>
>
> .
>
