linux-kernel - Re: [RFC PATCH] x86/cpufeatures: Flip the /proc/cpuinfo appearance logic

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Date: Tue, 18 Jun 2024 20:36:41 +0200
From: Borislav Petkov <bp@...en8.de>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Borislav Petkov <bp@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
	X86 ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] x86/cpufeatures: Flip the /proc/cpuinfo appearance
 logic

On Tue, Jun 18, 2024 at 07:06:13AM -0700, Sean Christopherson wrote:
> If we're going to churn the whole file, why not take the opportunity make it more
> structured?  E.g. use a variadic macro so the name doesn't need to be buried in a
> string inside a comment, and so that each feature doesn't have to open code the
> math.  Lack of third input omits the flag from /proc/cpuinfo, and a magic keyword,
> e.g. AUTO, uses the feature name.
> 
> There are quite a few games that could be played with macros, and IMO pretty much
> all of them would be better than comment+string shenanigans.
> 
> #define X86F(word, bit, abi_name...) ((word) * 32 + bit)
> 
> #define X86_FEATURE_FPU           X86F(0,  0, AUTO)
> 
> #define X86_FEATURE_XMM		  X86F(0, 25, SSE2)
> 
> #define X86_FEATURE_K8		  X86F(3,  4)

I'm always open to those things, sure. But it'll have to go ontop ofc.

"X86F(3, 4)" is not very readable but we'll get used to it. I like the aspect of
not having to open code the word math. But then having it opencoded is
maximally readable...

Yeah, we'll see what the others say too.

Thx.

-- 
Regards/Gruss,
    Boris.

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