tag namelibnvdimm-for-4.2 (dc238dde43b32a3681c2c4664cf61e0f8555126a)
tag date2015-06-26 10:21:21 -0700
tagged byDan Williams <>
tagged objectcommit 61031952f4...
The libnvdimm sub-system introduces, in addition to the libnvdimm-core,
4 drivers / enabling modules: NFIT: Instantiates an "nvdimm bus" with the core and registers memory devices (NVDIMMs) enumerated by the ACPI 6.0 NFIT (NVDIMM Firmware Interface table). After registering NVDIMMs the NFIT driver then registers "region" devices. A libnvdimm-region defines an access mode and the boundaries of persistent memory media. A region may span multiple NVDIMMs that are interleaved by the hardware memory controller. In turn, a libnvdimm-region can be carved into a "namespace" device and bound to the PMEM or BLK driver which will attach a Linux block device (disk) interface to the memory. PMEM: Initially merged in v4.1 this driver for contiguous spans of persistent memory address ranges is re-worked to drive PMEM-namespaces emitted by the libnvdimm-core. In this update the PMEM driver, on x86, gains the ability to assert that writes to persistent memory have been flushed all the way through the caches and buffers in the platform to persistent media. See memcpy_to_pmem() and wmb_pmem(). BLK: This new driver enables access to persistent memory media through "Block Data Windows" as defined by the NFIT. The primary difference of this driver to PMEM is that only a small window of persistent memory is mapped into system address space at any given point in time. Per-NVDIMM windows are reprogrammed at run time, per-I/O, to access different portions of the media. BLK-mode, by definition, does not support DAX. BTT: This is a library, optionally consumed by either PMEM or BLK, that converts a byte-accessible namespace into a disk with atomic sector update semantics (prevents sector tearing on crash or power loss). The sinister aspect of sector tearing is that most applications do not know they have a atomic sector dependency. At least today's disk's rarely ever tear sectors and if they do one almost certainly gets a CRC error on access. NVDIMMs will always tear and always silently. Until an application is audited to be robust in the presence of sector-tearing the usage of BTT is recommended. Thanks to: Ross Zwisler, Jeff Moyer, Vishal Verma, Christoph Hellwig, Ingo Molnar, Neil Brown, Boaz Harrosh, Robert Elliott, Matthew Wilcox, Andy Rudoff, Linda Knippers, Toshi Kani, Nicholas Moulin, Rafael Wysocki, and Bob Moore. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAABAgAGBQJVjZGBAAoJEB7SkWpmfYgC4fkP/j+k6HmSRNU/yRYPyo7CAWvj 3P5P1i6R6nMZZbjQrQArAXaIyLlFk4sEQDYsciR6dmslhhFZAkR2eFwVO5rBOyx3 QN0yxEpyjJbroRFUrV/BLaFK4cq2oyJAFFHs0u7/pLHBJ4MDMqfRKAMtlnBxEkTE LFcqXapSlvWitSbjMdIBWKFEvncaiJ2mdsFqT4aZqclBBTj00eWQvEG9WxleJLdv +tj7qR/vGcwOb12X5UrbQXgwtMYos7A6IzhHbqwQL8IrOcJ6YB8NopJUpLDd7ZVq KAzX6ZYMzNueN4uvv6aDfqDRLyVL7qoxM9XIjGF5R8SV9sF2LMspm1FBpfowo1GT h2QMr0ky1nHVT32yspBCpE9zW/mubRIDtXxEmZZ53DIc4N6Dy9jFaNVmhoWtTAqG b9pndFnjUzzieCjX5pCvo2M5U6N0AQwsnq76/CasiWyhSa9DNKOg8MVDRg0rbxb0 UvK0v8JwOCIRcfO3qiKcx+02nKPtjCtHSPqGkFKPySRvAdb+3g6YR26CxTb3VmnF etowLiKU7HHalLvqGFOlDoQG6viWes9Zl+ZeANBOCVa6rL2O7ZnXJtYgXf1wDQee fzgKB78BcDjXH4jHobbp/WBANQGN/GF34lse8yHa7Ym+28uEihDvSD1wyNLnefmo 7PJBbN5M5qP5tD0aO7SZ =VtWG -----END PGP SIGNATURE-----