[PATCH v2 08/25] arch: introduce memremap()

[Luis R. Rodriguez]

On Wed, Jul 29, 2015 at 08:50:04AM +0200, Christoph Hellwig wrote:
> On Mon, Jul 27, 2015 at 04:26:03PM -0700, Dan Williams wrote:
> > Oh, because all we have at this point is ioremap_cache() which
> > silently falls back.  It's not until the introduction of
> > arch_memremp() where we update the arch code to break that behavior.
> 
> Ok, makes sense.  Might be worth to document in the changelog.
> 
> > That said, I think it may be beneficial to allow a fallback if the
> > user cares.  So maybe memremap() can call plain ioremap() if
> > MEMREMAP_STRICT is not set and none of the other mapping types are
> > satisfied.
> 
> Is there a real use case for it?  Fallback APIs always seem confusing
> and it might make more sense to do this in the caller(s) that actually
> need it.

It seems semantics-wise we are trying to separate these two really, so I agree
with this. Having a fallback would onloy make things more complicated for any
sanitizer / checker / etc, and I don't think the practical gains of having a
fallback outweight the gains of having a clear semantic separation on intended
memory type and interactions with it.

  Luis