Re: [PATCH v1 05/10] powerpc/mm: Do early ioremaps from top to bottom on PPC64 too.

From: Christophe Leroy
Date: Tue Aug 20 2019 - 01:10:08 EST

Le 20/08/2019 Ã 02:20, Michael Ellerman a ÃcritÂ:
Nicholas Piggin <npiggin@xxxxxxxxx> writes:
Christophe Leroy's on August 14, 2019 6:11 am:
Until vmalloc system is up and running, ioremap basically
allocates addresses at the border of the IOREMAP area.

On PPC32, addresses are allocated down from the top of the area
while on PPC64, addresses are allocated up from the base of the
This series looks pretty good to me, but I'm not sure about this patch.

It seems like quite a small divergence in terms of code, and it looks
like the final result still has some ifdefs in these functions. Maybe
you could just keep existing behaviour for this cleanup series so it
does not risk triggering some obscure regression?

Yeah that is also my feeling. Changing it *should* work, and I haven't
found anything that breaks yet, but it's one of those things that's
bound to break something for some obscure reason.

Christophe do you think you can rework it to retain the different
allocation directions at least for now?

Yes I have started addressing the comments I received, and I think for now I'll keep all the machinery aside from the merge. Not sure yet if I'll leave it in pgtables_32/64.c or if I'll add ioremap_32/64.c