Re: [PATCH v4] panic: add panic_force_cpu= parameter to redirect panic to a specific CPU

Steven Rostedt
2026-01-08T16:36:17Z

On Thu, 8 Jan 2026 08:48:57 +0100
Peter Zijlstra <peterz@infradead.org> wrote:

> > + panic_force_cpu=
> > + [KNL,SMP] Force panic handling to execute on a specific CPU.
> > + Format: <cpu number>
> > + Some platforms require panic handling to occur on a
> > + specific CPU for the crash kernel to function correctly.
> > + This can be due to firmware limitations, interrupt routing
> > + constraints, or platform-specific requirements where only
> > + a particular CPU can safely enter the crash kernel.
> > + When set, panic() will redirect execution to the specified
> > + CPU before proceeding with the normal panic and kexec flow.
> > + If the target CPU is offline or unavailable, panic proceeds
> > + on the current CPU.
>
> It this stays; it should have a warning that it makes the panic less reliable.

Agreed. It should probably end with:

This option should only be used for systems with the above
constraints as it will cause the panic operation to be less
reliable.

-- Steve