[PATCHv6 0/3] enable nr_cpus for powerpc

Pingfan Liu piliu at redhat.com
Mon Sep 11 23:18:52 AEST 2023

Since my last v4 [1], the code has undergone great changes. The paca[]
array has been reorganized and indexed by paca_ptrs[], which
dramatically decreases the memory consumption even if there are many
unpresent cpus in the middle.

However, reordering the logical cpu numbers can further decrease the
size of paca_ptrs[] in the kdump case. So I keep [1/3], which
rotate-shifts the cpu's sequence number in the device tree to obtain the
logical cpu id.

Patch [2-3/3] make efforts to decrease the nr_cpus to be less than or
equal to two.

[1]: https://lore.kernel.org/linuxppc-dev/1520829790-14029-1-git-send-email-kernelfans@gmail.com/

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 linux.ibm.com>
Cc: Baoquan He <bhe at redhat.com>
Cc: Ming Lei <ming.lei at redhat.com>
Cc: kexec at lists.infradead.org
To: linuxppc-dev at lists.ozlabs.org

v5 -> v6:
  assign nr_cpu_ids by set_nr_cpu_ids() to tackle with the issue if nr_cpu_ids is
configured as a constant

Pingfan Liu (3):
  powerpc/setup: Loosen the mapping between cpu logical id and its seq
    in dt
  powerpc/setup: Handle the case when boot_cpuid greater than nr_cpus
  powerpc/setup: alloc extra paca_ptrs to hold boot_cpuid

 arch/powerpc/kernel/paca.c         |  10 +--
 arch/powerpc/kernel/prom.c         |  28 +++++---
 arch/powerpc/kernel/setup-common.c | 106 ++++++++++++++++++++++++-----
 3 files changed, 113 insertions(+), 31 deletions(-)


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