On Tue, Apr 28, 2015 at 3:30 PM, Dan Williams <dan.j.willi...@intel.com> wrote: > On Tue, Apr 28, 2015 at 2:10 PM, Andy Lutomirski <l...@amacapital.net> wrote: >> On Tue, Apr 28, 2015 at 11:26 AM, Dan Williams <dan.j.willi...@intel.com> >> wrote: >>> From: Ross Zwisler <ross.zwis...@linux.intel.com> >>> >>> The libnd implementation handles allocating dimm address space (DPA) >>> between PMEM and BLK mode interfaces. After DPA has been allocated from >>> a BLK-region to a BLK-namespace the nd_blk driver attaches to handle I/O >>> as a struct bio based block device. Unlike PMEM, BLK is required to >>> handle platform specific details like mmio register formats and memory >>> controller interleave. For this reason the libnd generic nd_blk driver >>> calls back into the bus provider to carry out the I/O. >>> >>> This initial implementation handles the BLK interface defined by the >>> ACPI 6 NFIT [1] and the NVDIMM DSM Interface Example [2] composed from >>> DCR (dimm control region), BDW (block data window), IDT (interleave >>> descriptor) NFIT structures and the hardware register format. >>> [1]: http://www.uefi.org/sites/default/files/resources/ACPI_6.0.pdf >>> [2]: http://pmem.io/documents/NVDIMM_DSM_Interface_Example.pdf >>> >>> Cc: Andy Lutomirski <l...@amacapital.net> >>> Cc: Boaz Harrosh <b...@plexistor.com> >>> Cc: H. Peter Anvin <h...@zytor.com> >>> Cc: Jens Axboe <ax...@fb.com> >>> Cc: Ingo Molnar <mi...@kernel.org> >>> Cc: Christoph Hellwig <h...@lst.de> >>> Signed-off-by: Ross Zwisler <ross.zwis...@linux.intel.com> >>> Signed-off-by: Dan Williams <dan.j.willi...@intel.com> >>> --- >>> drivers/block/nd/Kconfig | 12 + >>> drivers/block/nd/Makefile | 3 >>> drivers/block/nd/acpi.c | 422 >>> +++++++++++++++++++++++++++++++++++-- >>> drivers/block/nd/acpi_nfit.h | 47 ++++ >>> drivers/block/nd/blk.c | 264 +++++++++++++++++++++++ >>> drivers/block/nd/libnd.h | 11 + >>> drivers/block/nd/namespace_devs.c | 47 ++++ >>> drivers/block/nd/nd-private.h | 3 >>> drivers/block/nd/nd.h | 16 + >>> drivers/block/nd/region.c | 8 + >>> drivers/block/nd/region_devs.c | 65 +++++- >>> drivers/block/nd/test/nfit.c | 29 +++ >>> drivers/block/nd/test/nfit_test.h | 2 >>> 13 files changed, 891 insertions(+), 38 deletions(-) >>> create mode 100644 drivers/block/nd/blk.c >>> >>> diff --git a/drivers/block/nd/Kconfig b/drivers/block/nd/Kconfig >>> index 612bf2b14283..bac4290129fc 100644 >>> --- a/drivers/block/nd/Kconfig >>> +++ b/drivers/block/nd/Kconfig >>> @@ -95,6 +95,18 @@ config BLK_DEV_PMEM >>> >>> Say Y if you want to use a NVDIMM described by ACPI, E820, etc... >>> >>> +config ND_BLK >>> + tristate "BLK: Block data window (aperture) device support" >>> + depends on LIBND >>> + default ND_ACPI >>> + help >>> + This driver performs I/O using a set of mmio windows on a >>> + dimm. The set of apertures will all access the one DIMM. >>> + Multiple windows allow multiple threads to have a different >>> + portions of the dimm open at one time. >>> + >>> + Say Y if you want to use a NVDIMM with BLK-mode capability >>> + >> >> This describes how it works, not what it is. How about: >> >> This driver exposes NVDIMM BLK regions as block devices. BLK regions >> are regions of NVDIMM storage that are sector-addressable, not >> byte-addressible, and do not support DAX. > > They *are* byte-addressable albeit through an indirection window. The > indirection windows are too small for DAX to be a viable access mode.
Right, I was assuming incorrectly that the sector-atomic thing was a necessary part of BLK, or at least of this implementation. Anyway, I think my point stands: let's describe what these drivers do from a user's perspective, not how they work. --Andy -- Andy Lutomirski AMA Capital Management, LLC -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
