linux-kernel - Re: [PATCH] x86/mm/pkeys: Do not enable them by default

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Date:	Fri, 19 Feb 2016 19:31:28 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Dave Hansen <dave@...1.net>
Cc:	Dave Hansen <dave.hansen@...ux.intel.com>,
	linux-kernel@...r.kernel.org, brgerst@...il.com,
	tglx@...utronix.de, torvalds@...ux-foundation.org, hpa@...or.com,
	akpm@...ux-foundation.org, peterz@...radead.org, mingo@...nel.org,
	luto@...capital.net, dvlasenk@...hat.com, riel@...hat.com
Subject: Re: [PATCH] x86/mm/pkeys: Do not enable them by default

On Fri, Feb 19, 2016 at 09:49:02AM -0800, Dave Hansen wrote:
> For gains that small, we should barely even allow this thing to be
> configurable, much less default it to off.

Well, it's not about size gains only - it is also about adding code to
the kernel which is never going to be executed and also building it each
time on !pkey machines.

> Yes, agreed.  Distros _can_ override things.  But, In general,
> *especially* with user-visible effects, I'd really like defconfig (or
> other build defaults) to be reasonably close to what distributions do.

You can always add it to arch/x86/configs/x86_64_defconfig.

> My view has always been that the folks that really care about binary
> size are the ones that will be the ones digging through their .configs
> turning things off.

Except when automating "make oldconfig" and then wondering why all of a
sudden new features are enabled.

In my experience, it has always been the case that new features are
default off. What you want to achieve can easily be done without the
"def_bool y" thing.

-- 
Regards/Gruss,
    Boris.

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