linux-kernel - Re: [PATCH v3] x86/boot: Avoid writing to cr4 twice in startup

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Message-ID: <20250716132735.GAaHeox8nvd00imsIV@renoirsky.local>
Date: Wed, 16 Jul 2025 15:27:35 +0200
From: Borislav Petkov <bp@...en8.de>
To: Khalid Ali <khaliidcaliy@...il.com>
Cc: andrew.cooper3@...rix.com, ardb@...nel.org, brgerst@...il.com,
	dave.hansen@...ux.intel.com, hpa@...or.com,
	linux-kernel@...r.kernel.org, mingo@...hat.com, tglx@...utronix.de,
	ubizjak@...il.com, x86@...nel.org
Subject: Re: [PATCH v3] x86/boot: Avoid writing to cr4 twice in startup_64()

On Wed, Jul 16, 2025 at 09:07:20AM +0000, Khalid Ali wrote:
> I think the comment is misplaced. It is better if we move starting from "from the SDM"
> to below the endif. The second move the comment above it isn't useful also everyone knows 
> what PGE bit does, so it is better if we replace with the above misplaced comment.

The comment's fine. The %cr4 writes need a comment explaining what
they do because their sequence is special.

I don't mind documenting non-obvious asm in a more detailed fashion.

-- 
Regards/Gruss,
    Boris.

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