linux-kernel - Re: [RFC PATCH 20/56] x86/bugs: Move bugs.c logic out of .init section

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Message-ID: <DDJTJTL9GPRK.JPM92T0IHVTK@google.com>
Date: Thu, 16 Oct 2025 14:33:34 +0000
From: Brendan Jackman <jackmanb@...gle.com>
To: "Kaplan, David" <David.Kaplan@....com>, Brendan Jackman <jackmanb@...gle.com>, 
	Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...en8.de>, 
	Peter Zijlstra <peterz@...radead.org>, Josh Poimboeuf <jpoimboe@...nel.org>, 
	Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>, Ingo Molnar <mingo@...hat.com>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, "x86@...nel.org" <x86@...nel.org>, 
	"H . Peter Anvin" <hpa@...or.com>
Cc: Alexander Graf <graf@...zon.com>, Boris Ostrovsky <boris.ostrovsky@...cle.com>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 20/56] x86/bugs: Move bugs.c logic out of .init section

On Thu Oct 16, 2025 at 1:46 PM UTC, David Kaplan wrote:
> [AMD Official Use Only - AMD Internal Distribution Only]
>
>> -----Original Message-----
>> From: Brendan Jackman <jackmanb@...gle.com>
>> Sent: Thursday, October 16, 2025 7:32 AM
>> To: Kaplan, David <David.Kaplan@....com>; Thomas Gleixner
>> <tglx@...utronix.de>; Borislav Petkov <bp@...en8.de>; Peter Zijlstra
>> <peterz@...radead.org>; Josh Poimboeuf <jpoimboe@...nel.org>; Pawan Gupta
>> <pawan.kumar.gupta@...ux.intel.com>; Ingo Molnar <mingo@...hat.com>; Dave
>> Hansen <dave.hansen@...ux.intel.com>; x86@...nel.org; H . Peter Anvin
>> <hpa@...or.com>
>> Cc: Alexander Graf <graf@...zon.com>; Boris Ostrovsky
>> <boris.ostrovsky@...cle.com>; linux-kernel@...r.kernel.org
>> Subject: Re: [RFC PATCH 20/56] x86/bugs: Move bugs.c logic out of .init section
>>
>> Caution: This message originated from an External Source. Use proper caution
>> when opening attachments, clicking links, or responding.
>>
>>
>> On Mon Oct 13, 2025 at 2:34 PM UTC, David Kaplan wrote:
>> > If dynamic mitigations are supported, all the mitigation selection
>> > functions and mitigation choices may change at runtime.  Therefore, none of
>> > the functions may exist in .init and the data must not be read-only.
>>
>> I suppose we should have something akin to
>> __meminit/__init_or_module/__net_init here (like __init, but conditional
>> on Kconfig), so that users with CONFIG_DYNAMIC_MITIGATIONS=n can still
>> get the RAM back?
>
> Yeah, that's an option (maybe like __bugs_init).  Initial feedback I got was just to remove them from .init since they're now sometimes used later, but we could create a separate attribute tag.  Similar for the __ro_after_init ones.

OK, if you'd already thought of it and people didn't want the
maintenance burden, it's definitely not a big deal for me.