Comment # 7 on bug 1227345 from Maxime Thirion

Before kernel 6.9, all processor cores were active despite the NOAPIC option.

On the server with the i7, updates are applied 1x a week with automatic reboot.
The server has therefore been through all kernels since it was installed, and
the problem only started with 6.9.

The two machines were installed in early 2022.

As I haven't touched the Xeon yet, here are a few parameters:

kutta:~ # uname -a
Linux kutta.r-virtuel.net 6.4.6-1-default #1 SMP PREEMPT_DYNAMIC Tue Jul 25
04:42:30 UTC 2023 (55520bc) x86_64 x86_64 x86_64 GNU/Linux

kutta:~ # lscpu
Architecture:            x86_64
  CPU op-mode(s):        32-bit, 64-bit
  Address sizes:         39 bits physical, 48 bits virtual
  Byte Order:            Little Endian
CPU(s):                  8
  On-line CPU(s) list:   0-7
Vendor ID:               GenuineIntel
  BIOS Vendor ID:        Intel(R) Corporation
  Model name:            Intel(R) Xeon(R) CPU E3-1275 v5 @ 3.60GHz
    BIOS Model name:     Intel(R) Xeon(R) CPU E3-1275 v5 @ 3.60GHz To Be Filled
By O.E.M. CPU @ 3.6GHz
    BIOS CPU family:     179
    CPU family:          6
    Model:               94
    Thread(s) per core:  2
    Core(s) per socket:  4
    Socket(s):           1
    Stepping:            3
    CPU(s) scaling MHz:  92%
    CPU max MHz:         4000.0000
    CPU min MHz:         800.0000
    BogoMIPS:            7202.00
[...]

kutta:~ # cat /proc/cmdline 
BOOT_IMAGE=/boot/vmlinuz-6.4.6-1-default
root=UUID=8a392962-8a90-4306-8d47-919298279afd noapic quiet security=apparmor
mitigations=auto

kutta:~ # cat /etc/default/grub
# If you change this file, run 'grub2-mkconfig -o /boot/grub2/grub.cfg'
afterwards to update
# /boot/grub2/grub.cfg.

# Uncomment to set your own custom distributor. If you leave it unset or empty,
the default
# policy is to determine the value from /etc/os-release
GRUB_DISTRIBUTOR=
GRUB_DEFAULT=saved
GRUB_HIDDEN_TIMEOUT=0
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_TIMEOUT=0
GRUB_CMDLINE_LINUX_DEFAULT="noapic quiet security=apparmor mitigations=auto"
GRUB_CMDLINE_LINUX=""

# Uncomment to automatically save last booted menu entry in GRUB2 environment

# variable `saved_entry'
# GRUB_SAVEDEFAULT="true"
#Uncomment to enable BadRAM filtering, modify to suit your needs

# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
# GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"
#Uncomment to disable graphical terminal (grub-pc only)

GRUB_TERMINAL="gfxterm"
# The resolution used on graphical terminal
#note that you can use only modes which your graphic card supports via VBE

# you can see them in real GRUB with the command `vbeinfo'
GRUB_GFXMODE="auto"
# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
# GRUB_DISABLE_LINUX_UUID=true
#Uncomment to disable generation of recovery mode menu entries

# GRUB_DISABLE_RECOVERY="true"
#Uncomment to get a beep at grub start

# GRUB_INIT_TUNE="480 440 1"
GRUB_BACKGROUND=
GRUB_THEME=/boot/grub2/themes/openSUSE/theme.txt
SUSE_BTRFS_SNAPSHOT_BOOTING="true"
GRUB_DISABLE_OS_PROBER="false"
GRUB_ENABLE_CRYPTODISK="n"