linux-kernel - Re: [PATCH 1/2] x86/mm: Kill a 32-bit #ifdef for shared PMD handling

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Message-ID: <c620decfd3eb00df2aef3be5bdd98cae69916da4.camel@intel.com>
Date: Fri, 18 Apr 2025 20:07:28 +0000
From: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
To: "Hansen, Dave" <dave.hansen@...el.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "dave.hansen@...ux.intel.com"
	<dave.hansen@...ux.intel.com>
CC: "luto@...nel.org" <luto@...nel.org>, "jgross@...e.com" <jgross@...e.com>,
	"x86@...nel.org" <x86@...nel.org>, "joro@...tes.org" <joro@...tes.org>,
	"peterz@...radead.org" <peterz@...radead.org>, "bp@...en8.de" <bp@...en8.de>,
	"tglx@...utronix.de" <tglx@...utronix.de>, "kirill.shutemov@...ux.intel.com"
	<kirill.shutemov@...ux.intel.com>
Subject: Re: [PATCH 1/2] x86/mm: Kill a 32-bit #ifdef for shared PMD handling

On Fri, 2025-04-18 at 11:49 -0700, Dave Hansen wrote:
> I like the suggestion. I think I even wrote it that way originally.
> 
> I eventually decided to try and optimize for the lucky guy who comes
> through some day and is removing all the non-64-bit code. It would be
> easier for them to intuit that the cruft can go away here:
> 
> 	if (IS_ENABLED(CONFIG_X86_64))
> 		return;
> 	// cruft
> 
> Does that make sense, or am I optimizing for the wrong thing?

Hmm, we might expect such a person to be in a gleeful, tolerant mood. Also well
practiced in reasoning about similar conditionals. I see your point though.