linux-kernel - Re: [PATCH v2 1/1] cpuidle: sysfs: Display idle state enter function name

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Message-ID: <oifgpnkuupj4s7picyujw3jp2b22dcdrr7kqejho6uhxh3juam@7bqtbuxzjt5p>
Date: Thu, 20 Nov 2025 22:16:22 -0500
From: Aaron Tomlin <atomlin@...mlin.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: daniel.lezcano@...aro.org, gregkh@...uxfoundation.org, 
	nathan@...nel.org, linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/1] cpuidle: sysfs: Display idle state enter function
 name

On Thu, Nov 20, 2025 at 04:36:21PM +0100, Rafael J. Wysocki wrote:
> I'm not really sure how this helps.
> 
> For example, the intel_idle driver uses the same function for all idle
> states except for the polling one, which is already advertised as
> polling.
> 
> Besides, why do you want users to look into the kernel source code to
> figure things out?

Hi Rafael,

While intel_idle uses a single function for most states today, other
cpuidle drivers, different architectures, or future changes might implement
per-state variations.

The mapping from abstract C-state names and descriptions (e.g., "C1", "C3")
to the actual kernel implementation might not always be clear. Exposing the
enter function offers a direct, cheap and reliable way to easily identify
what is being executed for each state without using a kernel debugger
(e.g., crash(8). Finally user-space tools might benefit from introspecting
implementation details at runtime to validate configuration. This is
primarily for the advanced user.

Please let me know if this clarifies the motivation. 

Kind regards,
-- 
Aaron Tomlin