[PATCHv10 0/3] enable nr_cpus for powerpc without re-ordering cpu number

Pingfan Liu kernelfans at gmail.com
Wed Dec 27 13:39:31 AEDT 2023

From: Pingfan Liu <piliu at redhat.com>

This series addresses the nr_cpus issue for PowerPC without re-ordering
cpu number. To save the memory used by percpu area, it also limits the
possible cpu numbers by allowing hole in cpu_possible_mask.

Because the last cpu number will bigger than nr_cpu_ids in this way,
some pointer arrays indexed by cpu should be extended to hold the
pointer, e.g. paca_ptrs.

Please notice that this series still has some issue (some cpu can not be
brought up), but before I resolve it. Please share your thoughts about


Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: Nicholas Piggin <npiggin at gmail.com>
Cc: Christophe Leroy <christophe.leroy at csgroup.eu>
Cc: Mahesh Salgaonkar <mahesh at linux.ibm.com>
Cc: Wen Xiong <wenxiong at us.ibm.com>
Cc: Baoquan He <bhe at redhat.com>
Cc: Ming Lei <ming.lei at redhat.com>
Cc: Sourabh Jain <sourabhjain at linux.ibm.com>
Cc: Hari Bathini <hbathini at linux.ibm.com>
Cc: kexec at lists.infradead.org
To: linuxppc-dev at lists.ozlabs.org

Pingfan Liu (3):
  powerpc/kernel: Remove check on paca_ptrs_size
  powerpc/kernel: Extend arrays' size to make room for a hole in
  powerpc/smp: Allow hole in paca_ptrs to accommodate boot_cpu

 arch/powerpc/include/asm/paca.h    |  2 ++
 arch/powerpc/include/asm/smp.h     |  1 +
 arch/powerpc/kernel/paca.c         | 24 +++++++-----------------
 arch/powerpc/kernel/prom.c         |  6 ++++++
 arch/powerpc/kernel/setup-common.c | 26 +++++++++++++++++++++-----
 arch/powerpc/kernel/smp.c          |  3 ++-
 6 files changed, 39 insertions(+), 23 deletions(-)


More information about the Linuxppc-dev mailing list