Re: [PATCH 3/4] ARM: drop CONFIG_HIGHPTE support

Russell King (Oracle)
2024-12-11T13:51:03Z

On Wed, Dec 11, 2024 at 02:32:51PM +0100, Linus Walleij wrote:
> On Tue, Dec 10, 2024 at 5:06 PM Arnd Bergmann <arnd@kernel.org> wrote:
>
> > From: Arnd Bergmann <arnd@arndb.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@arndb.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.

Well... I use highmem routinely.

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