Re: [RFC PATCH] powerpc/64s: CONFIG_PPC_HASH_MMU

[Nicholas Piggin <npiggin@gmail.com>]

Michael Ellerman's on March 19, 2020 2:15 pm:
> Nicholas Piggin <npiggin@gmail.com> writes:
>> This allows the 64s hash MMU code to be compiled out if radix is
>> selected. This saves about 128kB kernel image size (90kB text) on
>> powernv_defconfig minus KVM, 40kB on a tiny config.
> 
> TBH my feelings are:
>  - the size savings don't excite me much, given our kernels can be ~32MB
>    in size.
>  - it's unlikely a major (or any) distro would ever enable this, so it
>    would not be well tested.

Yeah, it would only really be used for firmware or certain embedded 
things. We'd want some actual user before it's merged.

>  - it adds a *lot* of #ifdefs.

Yeah I started to get lazy, we can improve those quite a bit I think.

> So if we want to get this merged I'd want a good amount of refactoring
> done to avoid the bulk of the #ifdefs in the code. ie. lots of wrapper
> inlines etc. to hide the #ifdefs.
> 
> And someone to put up their hand to maintain it, ie. ensure it keeps
> building and fix any issues that come up when it breaks.

Yeah, I'll keep tinkering on it, it might come in useful.

Thanks,
Nick