linux-kernel - Re: [PATCH v7 1/4] x86/smp: Allow calling mwait_play

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Message-ID: <2320a952-334d-4d52-a15a-669a5670df7d@linux.intel.com>
Date: Tue, 17 Dec 2024 21:09:27 +0100
From: Patryk Wlazlyn <patryk.wlazlyn@...ux.intel.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
 rafael.j.wysocki@...el.com, peterz@...radead.org,
 dave.hansen@...ux.intel.com, gautham.shenoy@....com, tglx@...utronix.de,
 len.brown@...el.com, artem.bityutskiy@...ux.intel.com
Subject: Re: [PATCH v7 1/4] x86/smp: Allow calling mwait_play_dead with an
 arbitrary hint

> And honestly I'm wondering why adding a parameter to mwait_play_dead()
> is better than introducing mwait_play_dead_with_hint(), in analogy
> with the existing mwait_idle_with_hints()?
>
> The latter option would allow you to avoid introducing a function that
> is deleted in the same patch series (in patch 4).

We need to be able to call part of the old mwait_play_dead() code,
but without the hint calculation.

mwait_idle_with_hints() doesn't have the "kexec hack" logic.

We also need to leave the old code working and on top of that introduce
the acpi_idle and intel_idle patches that use the new API.

Now the old code is there and the new one. The only thing left is remove
the old code. I did it that way because of the comments earlier indicating
that I should not be breaking code in between.

Let me know if I answered your question or if I misunderstood something
now or earlier.

I'll apply your changelog suggestions when we agree on the implementation.