Re: [PATCH v3 3/3] powerpc/numa: Support coregroup on PowerNV
From: Srikar Dronamraju <hidden>
Date: 2026-09-04 11:34:49
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* Shrikanth Hegde [off-list ref] [2026-09-04 15:34:50]: Thanks Shrikanth for taking a look.
On 9/2/26 6:05 PM, Srikar Dronamraju wrote:quoted
Coregroup support on powerpc has so far been limited to PowerVM LPARs. However, PowerNV can also support coregroups when firmware exposes the required coregroup information through the associativity hierarchy.Existing firmware does expose this info already?
The corresponding skiboot changes were sent to the skiboot mailing list.
quoted
Detect coregroup support by checking whether primary_domain_index is the penultimate domain in the CPU node's ibm,associativity property. On PowerNV, a non-penultimate primary_domain_index indicates that firmware provides an additional level for coregroup information. This keeps the logic compatible with PowerVM systems, where primary_domain_index is likewise not the penultimate associativity domain.Could you please put the ibm,associativity on this powernv? as well PowerVM's so that one understands it better?
With this patch and the skiboot change, the ibm,associativity will look similar. For example on a Power10 Baremetal box with skiboot changes. $ lsprop /proc/device-tree/cpus/PowerPC,POWER10@*/ibm,associativity |& head -n 20 PowerPC,POWER10@0/ibm,associativity 00000005 00000000 00000000 00000000 00000000 00000000 PowerPC,POWER10@100/ibm,associativity 00000005 00000000 00000001 00000001 00000002 00000000 PowerPC,POWER10@108/ibm,associativity 00000005 00000000 00000001 00000001 00000002 00000002 PowerPC,POWER10@10/ibm,associativity 00000005 00000000 00000000 00000000 00000001 00000004 PowerPC,POWER10@110/ibm,associativity 00000005 00000000 00000001 00000001 00000003 00000004 PowerPC,POWER10@118/ibm,associativity 00000005 00000000 00000001 00000001 00000003 00000006 PowerPC,POWER10@120/ibm,associativity 00000005 00000000 00000001 00000001 00000002 00000008 PowerPC,POWER10@128/ibm,associativity 00000005 00000000 00000001 00000001 00000002 0000000a PowerPC,POWER10@130/ibm,associativity 00000005 00000000 00000001 00000001 00000003 0000000c PowerPC,POWER10@138/ibm,associativity 00000005 00000000 00000001 00000001 00000003 0000000e
quoted
Signed-off-by: Srikar Dronamraju <redacted> --- Changelog from v2: - Handle comments from Ritesh (one hunk needed to be moved from patch 2 to patch 3 to build correctly) Changelog from v1: https://lkml.kernel.org/r/20260524010017.140408-1-srikar@linux.ibm.com - Handle comments from Christophe Leroy; make code more flat arch/powerpc/mm/numa.c | 58 ++++++++++++++++++++++++++++++++++-------- 1 file changed, 48 insertions(+), 10 deletions(-)
-- Thanks and Regards Srikar Dronamraju