On Sun, Jul 26, 2015 at 10:12 PM, Christoph Hellwig <hch@xxxxxx> wrote: > On Sun, Jul 26, 2015 at 10:49:39AM -0700, Dan Williams wrote: >> On Sun, Jul 26, 2015 at 10:25 AM, Christoph Hellwig <hch@xxxxxx> wrote: >> > On Fri, Jul 24, 2015 at 10:38:42PM -0400, Dan Williams wrote: >> >> The behavior change to return NULL on an unsupported request is reserved >> >> for a later patch. >> > >> > Why? >> >> This is for drivers like pmem that care about the mapping type. For >> example, if pmem can't get a cache-enabled mapping it is potentially >> putting the write durability of the persistent media at risk. > > I understand that part, but the question is why the old behavior > is retained for now and only changed later. 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. 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. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
