Messages in this thread | | | Date | Thu, 14 May 2015 14:52:18 -0700 | Subject | Re: [PATCH v9 10/10] drivers/block/pmem: Map NVDIMM with ioremap_wt() | From | Dan Williams <> |
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On Wed, May 13, 2015 at 2:05 PM, Toshi Kani <toshi.kani@hp.com> wrote: > The pmem driver maps NVDIMM with ioremap_nocache() as we cannot > write back the contents of the CPU caches in case of a crash. > > This patch changes to use ioremap_wt(), which provides uncached > writes but cached reads, for improving read performance.
I'm thinking that for the libnd integration we don't want the pmem driver hard coding the cache-policy decision. This is something that should be specified to nd_pmem_region_create(). Especially considering that platform firmware tables (NFIT) may specify the cache policy for the range. As Matthew Wilcox mentioned offline we also must match the DAX-to-mmap cache policy with the policy for the driver mapping for architectures that are not capable of multiple mappings of the same physical address with different policies.
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