summaryrefslogtreecommitdiff
path: root/drivers/nvdimm
diff options
context:
space:
mode:
authorDan Williams <dan.j.williams@intel.com>2015-08-25 01:29:38 +0300
committerDan Williams <dan.j.williams@intel.com>2015-08-28 02:40:59 +0300
commit96601adb745186ccbcf5b078d4756f13381ec2af (patch)
tree1dff922da6a102e55978278c8ad078f30a7384b8 /drivers/nvdimm
parent41e94a851304f7acac840adec4004f8aeee53ad4 (diff)
downloadlinux-96601adb745186ccbcf5b078d4756f13381ec2af.tar.xz
x86, pmem: clarify that ARCH_HAS_PMEM_API implies PMEM mapped WB
Given that a write-back (WB) mapping plus non-temporal stores is expected to be the most efficient way to access PMEM, update the definition of ARCH_HAS_PMEM_API to imply arch support for WB-mapped-PMEM. This is needed as a pre-requisite for adding PMEM to the direct map and mapping it with struct page. The above clarification for X86_64 means that memcpy_to_pmem() is permitted to use the non-temporal arch_memcpy_to_pmem() rather than needlessly fall back to default_memcpy_to_pmem() when the pcommit instruction is not available. When arch_memcpy_to_pmem() is not guaranteed to flush writes out of cache, i.e. on older X86_32 implementations where non-temporal stores may just dirty cache, ARCH_HAS_PMEM_API is simply disabled. The default fall back for persistent memory handling remains. Namely, map it with the WT (write-through) cache-type and hope for the best. arch_has_pmem_api() is updated to only indicate whether the arch provides the proper helpers to meet the minimum "writes are visible outside the cache hierarchy after memcpy_to_pmem() + wmb_pmem()". Code that cares whether wmb_pmem() actually flushes writes to pmem must now call arch_has_wmb_pmem() directly. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> [hch: set ARCH_HAS_PMEM_API=n on x86_32] Reviewed-by: Christoph Hellwig <hch@lst.de> [toshi: x86_32 compile fixes] Signed-off-by: Toshi Kani <toshi.kani@hp.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/nvdimm')
-rw-r--r--drivers/nvdimm/pmem.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 3b5b9cb758b6..20bf122328da 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -125,7 +125,7 @@ static struct pmem_device *pmem_alloc(struct device *dev,
pmem->phys_addr = res->start;
pmem->size = resource_size(res);
- if (!arch_has_pmem_api())
+ if (!arch_has_wmb_pmem())
dev_warn(dev, "unable to guarantee persistence of writes\n");
if (!devm_request_mem_region(dev, pmem->phys_addr, pmem->size,