135 lines
3.7 KiB
Groff
135 lines
3.7 KiB
Groff
.\" Copyright (c) 2019 The FreeBSD Foundation, Inc.
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.\"
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.\" This documentation was written by
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.\" Konstantin Belousov <kib@FreeBSD.org> under sponsorship
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.\" from the FreeBSD Foundation.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd September 5, 2019
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.Dt NVDIMM 4
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.Os
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.Sh NAME
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.Nm nvdimm
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.Nd ACPI NVDIMM driver
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.Sh SYNOPSIS
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To load the driver as a module at boot, place the following line in
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.Xr loader.conf 5 :
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.Bd -literal -offset indent
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nvdimm_load="YES"
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.Ed
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.Sh DESCRIPTION
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.Bf -symbolic
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Note:
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The
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.Nm
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driver is under development and has some important limitations
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described below.
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.Ef
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.Pp
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The
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.Nm
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driver provides access to Non-Volatile DIMM (NVDIMM) persistent memory
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devices, which are ACPI-enumerated under the root NVDIMM device
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with a
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.Va _HID
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of
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.Dv ACPI0012
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and in the
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.Dv NFIT
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table.
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.Pp
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For each System Physical Address (SPA) Range described by NFIT, a
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device node
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.Pa /dev/nvdimm_spaNNN
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is created, where
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.Dv NNN
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is the SPA position in the table.
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The node can be used to
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.Xr read 2 ,
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.Xr write 2 ,
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or
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.Xr mmap 2
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the device.
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.Pp
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Also, for each SPA, the geom provider
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.Pa spaNNN
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is created, which can be used to create a conventional filesystem (e.g.,
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by
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.Xr newfs 8 )
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and
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.Xr mount 8
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it as any storage volume.
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Content accessible by
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.Pa /dev/nvdimm_spaNNN
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and
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.Pa /dev/spaNNN
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is coherent.
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.Pp
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The
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.Nm
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driver has support for reading NVDIMM namespaces (if supported by your
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hardware and already configured by some other mechanism, e.g., a BIOS
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configuration screen).
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The driver will provide a
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.Pa /dev/nvdimm_spaNNNnsMMM
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device node and
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.Pa spaNNNnsMMM
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geom provider for each namespace in a SPA, which behave analogously to their
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full-SPA cousins described above.
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.Sh SEE ALSO
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.Xr acpi 4 ,
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.Xr GEOM 4 ,
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.Xr geom 8 ,
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.Xr mount 8 ,
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.Xr newfs 8 ,
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.Xr disk 9
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.Sh HISTORY
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The
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.Nm
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driver first appeared in
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.Fx 12.0 .
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.Sh AUTHORS
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.An -nosplit
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The
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.Nm
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driver was originally written by
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.An Konstantin Belousov Aq Mt kib@FreeBSD.org ,
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and then updated by
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.An D. Scott Phillips Aq Mt scottph@FreeBSD.org .
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.Sh BUGS
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The
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.Nm
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driver does not utilize the Block Window interface, so if a write to an
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NVDIMM is interrupted due to a system crash or power outage,
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the corresponding page might be left in a partially updated state.
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.Pp
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There is no support for Device-Specific Methods (DSM), used to report and
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control device health and wearing.
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.Pp
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The driver depends on the
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.Xr pmap_largemap 9
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pmap interface, which is currently only implemented on amd64.
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The interface can be only reasonable implemented on 64bit architectures.
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