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

[Vladimir Murzin]

On 3/9/22 4:17 PM, Arnd Bergmann wrote:
> 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.
> 

I'd appreciate if you keep them since I run Cortex-R52...

Cheers
Vladimir

>         Arnd
>