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[PATCHv5,0/3] enable nr_cpus for powerpc

Message ID 20230908141941.13660-1-piliu@redhat.com (mailing list archive)
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Series enable nr_cpus for powerpc | expand

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Pingfan Liu Sept. 8, 2023, 2:19 p.m. UTC 
It is a long time 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@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Cc: Wen Xiong <wenxiong@linux.ibm.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: kexec@lists.infradead.org
To: linuxppc-dev@lists.ozlabs.org

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         |  26 ++++---
 arch/powerpc/kernel/setup-common.c | 106 ++++++++++++++++++++++++-----
 3 files changed, 111 insertions(+), 31 deletions(-)