[PATCH 2/2] ARM: remove support for NOMMU ARMv4/v5

[Arnd Bergmann]

On Wed, Mar 9, 2022 at 4:48 PM Robin Murphy <robin.murphy at arm.com> wrote:
>
> On 2022-03-09 14:40, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd at arndb.de>
> >
> > It is possible to build MMU-less kernels for Cortex-M base
> > microcrontrollers as well as a couple of older platforms that
> > have not been converted to CONFIG_ARCH_MULTIPLATFORM,
> > specifically ep93xx, footbridge, dove, sa1100 and s3c24xx.
> >
> > It seems unlikely that anybody has tested those configurations
> > in recent years, as even building them is frequently broken.
> > A patch I submitted caused another build time regression
> > in this configuration. I sent a patch for that, but it seems
> > better to also remove the option entirely, leaving ARMv7-M
> > as the only supported Arm NOMMU target for simplicity.
>
> In that case, it would probably make sense to garbage-collect all the
> configs, setup code and other stuff relating to older MMU-less CPU cores
> like ARM1156, ARM940, etc. at the same time.

Right, good idea. These are only selected by CONFIG_ARCH_INTEGRATOR,
but that in turn doesn't build for CONFIG_MMU=n because it depends on
ARCH_MULTIPLATFORM. I'll send a patch for these.

I also went back and forth between removing the #ifdefs in
arch/arm/mm/proc-*.S for this patch, though I did not do that in the end.
We may still want them at least for proc-v7.S because that is a small
chance that someone will want to support Cortex-R.

        Arnd