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

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Message-ID: <20260112074910.GC830755@noisy.programming.kicks-ass.net>
Date: Mon, 12 Jan 2026 08:49:10 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Pnina Feder <PNINA.FEDER@...ileye.com>
Cc: "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"pmladek@...e.com" <pmladek@...e.com>,
	"bhe@...hat.com" <bhe@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"lkp@...el.com" <lkp@...el.com>,
	"mgorman@...e.de" <mgorman@...e.de>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"rostedt@...dmis.org" <rostedt@...dmis.org>,
	"senozhatsky@...omium.org" <senozhatsky@...omium.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	Vladimir Kondratiev <Vladimir.Kondratiev@...ileye.com>
Subject: Re: [PATCH v4] panic: add panic_force_cpu= parameter to redirect
 panic to a specific CPU

On Thu, Jan 08, 2026 at 08:09:33PM +0000, Pnina Feder wrote:

> > Also, if this is a 'requirement' for kexec or the like, this
> > shouldn't be a command line argument, but something that's set-up by
> > kexec itself for functional reasons.
> 
> Since the redirection needs to happen before other CPUs are stopped,
> would a sysctl be preferable? The user could set it when loading the
> crash kernel.

I was more thinking about platform setup, it would set this on boot, and
equally dis-allow hot-unplug of the magical CPU.