[PATCH v3 0/3] Enable crash hotplug support on powerpc

[Sourabh Jain]

The primary goal of this patch series is to enable crash hotplug on
powerpc architecture for the `kexec_load` system call.

The first patch in the series introduces a new kexec flag added in the
kernel to generalize crash hotplug support. The second patch enables
crash hotplug support on PowerPC for `kexec_load` system call. The third
patch updates the documentation about crash hotplug support.

Changes log:

v4:
  - Do not remove the KEXEC_UPDATE_ELFCOREHDR kexec flag. It is needed to
    maintain backward compatibility on x86. 1/3
  - Send the KEXEC_UPDATE_ELFCOREHDR kexec flag for x86, and for the rest
    of the architectures, send KEXEC_CRASH_HOTPLUG_SUPPORT to enable
    crash hotplug support kexec_load system call. 1/3
  - Since there is a significant change in 1/3, hence Hari's Acked-by
    is removed form only first patch. 1/3
  - Rename and reorder the function arch_do_exclude_segment() parameters
    as suggested. 1/3
  - Keep the implementation of arch_do_exclude_segment() function same
    for x86_64 and i386. 1/3

v3:
  https://lists.infradead.org/pipermail/kexec/2024-July/030361.html
  - Updated --hotplug option description 3/3

v2:
  https://lists.infradead.org/pipermail/kexec/2024-June/030309.html
  - Find CPUs in the system using the /sys/devices/system/cpu/present sysfs
    instead of traversing all nodes under /proc/device-tree/cpus. 2/3
  - Added a new function to find present CPUs in the system. 2/3
  - Removed unnecessary NULL check on seg_ptr from arch_do_exclude_segment(). 2/3
  - Updated --hotplug option description 3/3

v1:
  https://lists.infradead.org/pipermail/kexec/2024-May/030051.html


Cc: Aditya Gupta <adityag at linux.ibm.com>
Cc: Baoquan He <bhe at redhat.com>
Cc: Coiby Xu <coxu at redhat.com>
Cc: Hari Bathini <hbathini at linux.ibm.com>
Cc: Mahesh Salgaonkar <mahesh at linux.ibm.com>
Cc: Simon Horman <horms at kernel.org>
Cc: Sourabh Jain <sourabhjain at linux.ibm.com>

Sourabh Jain (3):
  kexec_load: Use new kexec flag for hotplug support
  powerpc/kexec_load: add hotplug support
  doc/hotplug: update man and --help

 kexec/arch/arm/kexec-arm.c             |   5 +
 kexec/arch/arm64/kexec-arm64.c         |   5 +
 kexec/arch/cris/kexec-cris.c           |   4 +
 kexec/arch/hppa/kexec-hppa.c           |   5 +
 kexec/arch/i386/kexec-x86.c            |   8 +
 kexec/arch/ia64/kexec-ia64.c           |   4 +
 kexec/arch/loongarch/kexec-loongarch.c |   5 +
 kexec/arch/m68k/kexec-m68k.c           |   5 +
 kexec/arch/mips/kexec-mips.c           |   4 +
 kexec/arch/ppc/kexec-ppc.c             |   4 +
 kexec/arch/ppc64/crashdump-ppc64.c     |  16 +-
 kexec/arch/ppc64/fdt.c                 | 236 ++++++++++++++++++++++++-
 kexec/arch/ppc64/include/arch/fdt.h    |   2 +-
 kexec/arch/ppc64/kexec-elf-ppc64.c     |   2 +-
 kexec/arch/ppc64/kexec-ppc64.c         |  12 ++
 kexec/arch/s390/kexec-s390.c           |   5 +
 kexec/arch/sh/kexec-sh.c               |   5 +
 kexec/arch/x86_64/kexec-x86_64.c       |   8 +
 kexec/kexec-syscall.h                  |   1 +
 kexec/kexec.8                          |   8 +-
 kexec/kexec.c                          |  44 ++++-
 kexec/kexec.h                          |   2 +
 22 files changed, 373 insertions(+), 17 deletions(-)

-- 
2.45.1