linux-kernel - Re: [PATCH v11 04/13] x86/cpufeatures: Add Bandwidth Monitoring Event Configuration feature flag

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Message-ID: <Y7yJq2lV262EPCQT@zn.tnic>
Date:   Mon, 9 Jan 2023 22:39:55 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Luck, Tony" <tony.luck@...el.com>
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Subject: Re: [PATCH v11 04/13] x86/cpufeatures: Add Bandwidth Monitoring
 Event Configuration feature flag

On Mon, Jan 09, 2023 at 09:25:32PM +0000, Luck, Tony wrote:
> It feels like the old "rule" was "make it visible in /proc/cpuid" unless there was some
> good reason NOT to do it.  But that has resulted in the "flags" line getting ridiculously
> long and hard for humans to read (141 fields with 926 bytes on my Skylake,
> more on more modern CPUs).

Yap, imagine every possible CPUID bit were in there...

> I don't know if we'd break anything if we dropped:
> 
>   cat_l3 cdp_l3 mba cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local
> 
> from /proc/cpuinfo.

I wouldn't mind if we remove them from cpuinfo, frankly.

> Perhaps the "rule" should be written in Documentation/{somewhere}?

This started documenting it:

Documentation/x86/cpuinfo.rst

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette