linux-kernel - Re: [PATCH v4] x86/bugs: Add a separate config for each mitigation

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Message-ID: <20231015150615.GAZSv/59aIrSnprCKg@fat_crate.local>
Date:   Sun, 15 Oct 2023 17:06:15 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Josh Poimboeuf <jpoimboe@...nel.org>
Cc:     Breno Leitao <leitao@...ian.org>, tglx@...utronix.de,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>, leit@...a.com,
        "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4] x86/bugs: Add a separate config for each mitigation

On Thu, Oct 12, 2023 at 09:48:14AM -0700, Josh Poimboeuf wrote:
> It adds clarity by making the options more self-documenting.

Why would you want to highlight mitigation-specific Kconfig options? You
grep for the symbol and you find what it is.

Why do the mitigation options need to self-document at all?

> For users who care about such things it makes it easier to identify
> which options they need to enable or disable.  And it makes it clearer
> what those options do without having to go read the docs.

Sorry, if I see CONFIG_MITIGATE_X and CONFIG_X, I still wanna go see
what X is.  And we enable the defaults for users - they don't really
need to read the docs.

> For developers it helps code readability: "ah, this nasty code is for a
> side channel mitigation".  Also it makes it easier to grep for.

It doesn't matter - Kconfig options are Kconfig options. We grep
regardless.

> Right, but we have a global option for that.  I was wondering if anybody
> actually uses the individual options (though I agree with Linus they
> should exist to help with code readability).

Read Linus' mail - there is some merit to having separate options.

-- 
Regards/Gruss,
    Boris.

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