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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20241211142517.fhnOz46I@linutronix.de>
Date: Wed, 11 Dec 2024 15:25:17 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
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>,
	Linus Walleij <linus.walleij@...aro.org>,
	Mark Rutland <mark.rutland@....com>,
	Matthew Wilcox <willy@...radead.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Russell King <linux@...linux.org.uk>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH 3/4] ARM: drop CONFIG_HIGHPTE support

On 2024-12-10 17:05:55 [+0100], Arnd Bergmann 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 sent a patch to drop HIGHPTE support on x86 today, see
> https://lore.kernel.org/lkml/20241210144945.2325330-9-arnd@kernel.org/T/#u
> 
> If that one gets merged, we can merge this one instead of the one
> that makes HIGHPTE depend on !PREEMPT_RT, but if we decide against
> the x86 change, then we probably don't want this one either.

Based on what I have written in 20241211140402.yf7gMExr@...utronix.de it
makes sense.

Acked-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>

Sebastian