linux-stable/Documentation/admin-guide/kdump
Thomas Gleixner 5c5682b9f8 x86/cpu: Detect real BSP on crash kernels
When a kdump kernel is started from a crashing CPU then there is no
guarantee that this CPU is the real boot CPU (BSP). If the kdump kernel
tries to online the BSP then the INIT sequence will reset the machine.

There is a command line option to prevent this, but in case of nested kdump
kernels this is wrong.

But that command line option is not required at all because the real
BSP is enumerated as the first CPU by firmware. Support for the only
known system which was different (Voyager) got removed long ago.

Detect whether the boot CPU APIC ID is the first APIC ID enumerated by
the firmware. If the first APIC ID enumerated is not matching the boot
CPU APIC ID then skip registering it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Link: https://lore.kernel.org/r/20240213210252.348542071@linutronix.de
2024-02-15 22:07:43 +01:00
..
gdbmacros.txt docs: gdbmacros: print newest record 2023-01-03 10:44:14 +01:00
index.rst
kdump.rst x86/cpu: Detect real BSP on crash kernels 2024-02-15 22:07:43 +01:00
vmcoreinfo.rst mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER 2024-01-08 15:27:15 -08:00