2 .\" Copyright (c) 2012-2014 Intel Corporation
3 .\" All rights reserved.
5 .\" Redistribution and use in source and binary forms, with or without
6 .\" modification, are permitted provided that the following conditions
8 .\" 1. Redistributions of source code must retain the above copyright
9 .\" notice, this list of conditions, and the following disclaimer,
10 .\" without modification.
11 .\" 2. Redistributions in binary form must reproduce at minimum a disclaimer
12 .\" substantially similar to the "NO WARRANTY" disclaimer below
13 .\" ("Disclaimer") and any redistribution must be conditioned upon
14 .\" including a substantially similar Disclaimer requirement for further
15 .\" binary redistribution.
18 .\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 .\" "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 .\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
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30 .\" nvme driver man page.
32 .\" Author: Jim Harris <jimharris@FreeBSD.org>
41 .Nd NVM Express core driver
43 To compile this driver into your kernel,
44 place the following line in your kernel configuration file:
45 .Bd -ragged -offset indent
49 Or, to load the driver as a module at boot, place the following line in
51 .Bd -literal -offset indent
55 Most users will also want to enable
57 to surface NVM Express namespaces as disk devices which can be
59 Note that in NVM Express terms, a namespace is roughly equivalent to a
64 driver provides support for NVM Express (NVMe) controllers, such as:
67 Hardware initialization
69 Per-CPU IO queue pairs
71 API for registering NVMe namespace consumers such as
74 API for submitting NVM commands to namespaces
76 Ioctls for controller and namespace configuration and management
81 driver creates controller device nodes in the format
83 and namespace device nodes in
86 Note that the NVM Express specification starts numbering namespaces at 1,
87 not 0, and this driver follows that convention.
92 will create an I/O queue pair for each CPU, provided enough MSI-X vectors
94 To force a single I/O queue pair shared by all CPUs, set the following
97 .Bd -literal -offset indent
98 hw.nvme.per_cpu_io_queues=0
101 To force legacy interrupts for all
103 driver instances, set the following tunable value in
105 .Bd -literal -offset indent
109 Note that use of INTx implies disabling of per-CPU I/O queue pairs.
111 The following controller-level sysctls are currently implemented:
112 .Bl -tag -width indent
113 .It Va dev.nvme.0.int_coal_time
114 (R/W) Interrupt coalescing timer period in microseconds.
116 .It Va dev.nvme.0.int_coal_threshold
117 (R/W) Interrupt coalescing threshold in number of command completions.
121 The following queue pair-level sysctls are currently implemented.
122 Admin queue sysctls take the format of dev.nvme.0.adminq and I/O queue sysctls
123 take the format of dev.nvme.0.ioq0.
124 .Bl -tag -width indent
125 .It Va dev.nvme.0.ioq0.num_entries
126 (R) Number of entries in this queue pair's command and completion queue.
127 .It Va dev.nvme.0.ioq0.num_tr
128 (R) Number of nvme_tracker structures currently allocated for this queue pair.
129 .It Va dev.nvme.0.ioq0.num_prp_list
130 (R) Number of nvme_prp_list structures currently allocated for this queue pair.
131 .It Va dev.nvme.0.ioq0.sq_head
132 (R) Current location of the submission queue head pointer as observed by
134 The head pointer is incremented by the controller as it takes commands off
135 of the submission queue.
136 .It Va dev.nvme.0.ioq0.sq_tail
137 (R) Current location of the submission queue tail pointer as observed by
139 The driver increments the tail pointer after writing a command
140 into the submission queue to signal that a new command is ready to be
142 .It Va dev.nvme.0.ioq0.cq_head
143 (R) Current location of the completion queue head pointer as observed by
145 The driver increments the head pointer after finishing
146 with a completion entry that was posted by the controller.
147 .It Va dev.nvme.0.ioq0.num_cmds
148 (R) Number of commands that have been submitted on this queue pair.
149 .It Va dev.nvme.0.ioq0.dump_debug
150 (W) Writing 1 to this sysctl will dump the full contents of the submission
151 and completion queues to the console.
161 driver first appeared in
167 driver was developed by Intel and originally written by
168 .An Jim Harris Aq jimharris@FreeBSD.org ,
169 with contributions from Joe Golio at EMC.
171 This man page was written by
172 .An Jim Harris Aq jimharris@FreeBSD.org .