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

Dan Williams
2015-07-29T18:33:27Z

On Wed, Jul 29, 2015 at 11:27 AM, Luis R. Rodriguez <mcgrof@suse.com> wrote:
> 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.
>

Yup, consider it dropped. Drivers that want fallback behavior can do
it explicitly.