linux-kernel - Re: [PATCH v2 2/3] x86/smp: Allow forcing the mwait hint for play dead loop

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Message-ID: <b01cc6de-8440-477a-9844-d921da9dceb7@intel.com>
Date: Wed, 30 Oct 2024 13:11:05 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>,
 Patryk Wlazlyn <patryk.wlazlyn@...ux.intel.com>, x86@...nel.org,
 linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
 rafael.j.wysocki@...el.com, len.brown@...el.com, dave.hansen@...ux.intel.com
Subject: Re: [PATCH v2 2/3] x86/smp: Allow forcing the mwait hint for play
 dead loop

On 10/30/24 12:53, Rafael J. Wysocki wrote:
> clearly referred to as a kexec() hack, which cannot be done in
> cpuidle_play_dead() because the cpuidle driver doesn't know how to get
> to md->control.

What if we have an mwait_play_dead() _helper_?  It takes the hint as an
argument and retains all the kexec hacks.  All the cpuidle driver has to
do is call the helper with the hint that the cpuidle driver determines.