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/dev/dax, pmem: direct access to persistent memory

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Device DAX is the device-centric analogue of Filesystem DAX
(CONFIG_FS_DAX).  It allows memory ranges to be allocated and mapped
without need of an intervening file system.  Device DAX is strict,
precise and predictable.  Specifically this interface:

1/ Guarantees fault granularity with respect to a given page size (pte,
pmd, or pud) set at configuration time.

2/ Enforces deterministic behavior by being strict about what fault
scenarios are supported.

For example, by forcing MADV_DONTFORK semantics and omitting MAP_PRIVATE
support device-dax guarantees that a mapping always behaves/performs the
same once established.  It is the "what you see is what you get" access
mechanism to differentiated memory vs filesystem DAX which has
filesystem specific implementation semantics.

Persistent memory is the first target, but the mechanism is also
targeted for exclusive allocations of performance differentiated memory
ranges.

This commit is limited to the base device driver infrastructure to
associate a dax device with pmem range.

Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams
2016-05-18 09:15:08 -07:00
parent 6cf9c5babd
commit ab68f26221
9 changed files with 478 additions and 0 deletions
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9
tools/testing/nvdimm/Kbuild
View File

@@ -16,6 +16,7 @@ ldflags-y += --wrap=phys_to_pfn_t
DRIVERS := ../../../drivers
NVDIMM_SRC := $(DRIVERS)/nvdimm
ACPI_SRC := $(DRIVERS)/acpi
DAX_SRC := $(DRIVERS)/dax
obj-$(CONFIG_LIBNVDIMM) += libnvdimm.o
obj-$(CONFIG_BLK_DEV_PMEM) += nd_pmem.o
@@ -23,6 +24,8 @@ obj-$(CONFIG_ND_BTT) += nd_btt.o
obj-$(CONFIG_ND_BLK) += nd_blk.o
obj-$(CONFIG_X86_PMEM_LEGACY) += nd_e820.o
obj-$(CONFIG_ACPI_NFIT) += nfit.o
obj-$(CONFIG_DEV_DAX) += dax.o
obj-$(CONFIG_DEV_DAX_PMEM) += dax_pmem.o
nfit-y := $(ACPI_SRC)/nfit.o
nfit-y += config_check.o
@@ -39,6 +42,12 @@ nd_blk-y += config_check.o
nd_e820-y := $(NVDIMM_SRC)/e820.o
nd_e820-y += config_check.o
dax-y := $(DAX_SRC)/dax.o
dax-y += config_check.o
dax_pmem-y := $(DAX_SRC)/pmem.o
dax_pmem-y += config_check.o
libnvdimm-y := $(NVDIMM_SRC)/core.o
libnvdimm-y += $(NVDIMM_SRC)/bus.o
libnvdimm-y += $(NVDIMM_SRC)/dimm_devs.o

2
tools/testing/nvdimm/config_check.c
View File

@@ -12,4 +12,6 @@ void check(void)
BUILD_BUG_ON(!IS_MODULE(CONFIG_ND_BTT));
BUILD_BUG_ON(!IS_MODULE(CONFIG_ND_BLK));
BUILD_BUG_ON(!IS_MODULE(CONFIG_ACPI_NFIT));
BUILD_BUG_ON(!IS_MODULE(CONFIG_DEV_DAX));
BUILD_BUG_ON(!IS_MODULE(CONFIG_DEV_DAX_PMEM));
}