linux-kernel - Re: [PATCH v12 23/31] x86/resctrl: Add energy/perf choices to rdt boot option

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Message-ID: <1d9b83e6-48b3-4e62-a9aa-09947013c907@intel.com>
Date: Thu, 23 Oct 2025 10:45:57 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Tony Luck <tony.luck@...el.com>, Fenghua Yu <fenghuay@...dia.com>, "Maciej
 Wieczor-Retman" <maciej.wieczor-retman@...el.com>, Peter Newman
	<peternewman@...gle.com>, James Morse <james.morse@....com>, Babu Moger
	<babu.moger@....com>, Drew Fustini <dfustini@...libre.com>, Dave Martin
	<Dave.Martin@....com>, Chen Yu <yu.c.chen@...el.com>
CC: <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
	<patches@...ts.linux.dev>
Subject: Re: [PATCH v12 23/31] x86/resctrl: Add energy/perf choices to rdt
 boot option

Hi Tony,

On 10/13/25 3:33 PM, Tony Luck wrote:
> Legacy resctrl features are enumerated by X86_FEATURE_* flags. These
> may be overridden by quirks to disable features in the case of errata.
> Users can use kernel command line options to either disable a feature,
> or to force enable a feature that was disabled by a quirk.
> 
> Provide similar functionality for hardware features that do not have an
> X86_FEATURE_* flag.  Unlike other features that are tied to X86_FEATURE_*
> flags, these must be queried by name. Add rdt_is_feature_enabled()
> to check whether quirks or kernel command line have disabled a feature.
> 
> Users may force a feature to be disabled. E.g. "rdt=!perf" will ensure
> that none of the perf telemetry events are enabled.
> 
> Resctrl architecture code may disable a feature that does not provide
> full functionality. Users may override that decision.  E.g. "rdt=energy"
> will enable any available energy telemetry events even if they do not
> provide full functionality.
> 
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---

Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>

Reinette