linux-kernel - Re: [PATCH 3/4] ARM: drop CONFIG

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Message-ID: <CACRpkdZoRbJ4DwRpZQMKbEAvzg4AAdp4B+94SFLm1ssiQmjUwQ@mail.gmail.com>
Date: Wed, 11 Dec 2024 14:32:51 +0100
From: Linus Walleij <linus.walleij@...aro.org>
To: Arnd Bergmann <arnd@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	Arnd Bergmann <arnd@...db.de>, linux-mm@...ck.org, linux-rt-devel@...ts.linux.dev, 
	Ard Biesheuvel <ardb@...nel.org>, Clark Williams <clrkwllms@...nel.org>, Jason Baron <jbaron@...mai.com>, 
	Josh Poimboeuf <jpoimboe@...nel.org>, Mark Rutland <mark.rutland@....com>, 
	Matthew Wilcox <willy@...radead.org>, Peter Zijlstra <peterz@...radead.org>, 
	Russell King <linux@...linux.org.uk>, Sebastian Andrzej Siewior <bigeasy@...utronix.de>, 
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH 3/4] ARM: drop CONFIG_HIGHPTE support

On Tue, Dec 10, 2024 at 5:06 PM Arnd Bergmann <arnd@...nel.org> wrote:

> From: Arnd Bergmann <arnd@...db.de>
>
> CONFIG_HIGHPTE was added in linux-2.6.32, a few years before 64-bit
> support. At the time it made sense, as the CONFIG_ARM_LPAE option allowed
> systems with 16GB of memory that made lowmem a particularly scarce
> resource, and the HIGHPTE implementation gave feature parity with 32-bit
> x86 and frv machines.
>
> Since Arm is the last architecture remaining that uses this, and almost
> no 32-bit machines support more than 4GB of RAM, the cost of continuing
> to maintain HIGHPTE seems unjustified, so remove it here to allow
> simplifying the generic page table handling.
>
> Link: https://lore.kernel.org/lkml/20241204103042.1904639-8-arnd@kernel.org/T/#u
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

I'm in favor of this if the x86 patch goes in. We need to get rid
of highmem anyway and this will need to happen sooner or later
either way.
Acked-by: Linus Walleij <linus.walleij@...aro.org>

Yours,
Linus Walleij