1.\" 2.\" Copyright (c) 2012-2013 Intel Corporation 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 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. 16.\" 17.\" NO WARRANTY 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 21.\" A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 22.\" HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 26.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 27.\" IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGES. 29.\" 30.\" nvme driver man page. 31.\" 32.\" Author: Jim Harris <jimharris@FreeBSD.org> 33.\" 34.\" $FreeBSD$ 35.\" 36.Dd July 9, 2013 37.Dt NVME 4 38.Os 39.Sh NAME 40.Nm nvme 41.Nd NVM Express core driver 42.Sh SYNOPSIS 43To compile this driver into your kernel, 44place the following line in your kernel configuration file: 45.Bd -ragged -offset indent 46.Cd "device nvme" 47.Ed 48.Pp 49Or, to load the driver as a module at boot, place the following line in 50.Xr loader.conf 5 : 51.Bd -literal -offset indent 52nvme_load="YES" 53.Ed 54.Pp 55Most users will also want to enable 56.Xr nvd 4 57to surface NVM Express namespaces as disk devices. 58Note that in NVM Express terms, a namespace is roughly equivalent to a 59SCSI LUN. 60.Sh DESCRIPTION 61The 62.Nm 63driver provides support for NVM Express (NVMe) controllers, such as: 64.Bl -bullet 65.It 66Hardware initialization 67.It 68Per-CPU IO queue pairs 69.It 70API for registering NVMe namespace consumers such as 71.Xr nvd 4 72.It 73API for submitting NVM commands to namespaces 74.It 75Ioctls for controller and namespace configuration and management 76.Nm 77creates controller devices in the format /dev/nvmeX and namespace devices in 78the format /dev/nvmeXnsY. 79Note that the NVM Express specification starts numbering namespaces at 1, 80not 0, and this driver follows that convention. 81.El 82.Sh CONFIGURATION 83By default, 84.Nm 85will create an I/O queue pair for each CPU, provided enough MSI-X vectors 86can be allocated. 87To force a single I/O queue pair shared by all CPUs, set the following 88tunable value in 89.Xr loader.conf 5 : 90.Bd -literal -offset indent 91hw.nvme.per_cpu_io_queues=0 92.Ed 93.Pp 94To force legacy interrupts for all 95.Nm 96driver instances, set the following tunable value in 97.Xr loader.conf 5 : 98.Bd -literal -offset indent 99hw.nvme.force_intx=1 100.Ed 101.Pp 102Note that use of INTx implies disabling of per-CPU I/O queue pairs. 103.Sh SYSCTL VARIABLES 104The following controller-level sysctls are currently implemented: 105.Bl -tag -width indent 106.It Va dev.nvme.0.int_coal_time 107(R/W) Interrupt coalescing timer period in microseconds. Set to 0 to disable. 108.It Va dev.nvme.0.int_coal_threshold 109(R/W) Interrupt coalescing threshold in number of command completions. 110Set to 0 to disable. 111.El 112.Pp 113The following queue pair-level sysctls are currently implemented. 114Admin queue sysctls take the format of dev.nvme.0.adminq and I/O queue sysctls 115take the format of dev.nvme.0.ioq0. 116.Bl -tag -width indent 117.It Va dev.nvme.0.ioq0.num_entries 118(R) Number of entries in this queue pair's command and completion queue. 119.It Va dev.nvme.0.ioq0.num_tr 120(R) Number of nvme_tracker structures currently allocated for this queue pair. 121.It Va dev.nvme.0.ioq0.num_prp_list 122(R) Number of nvme_prp_list structures currently allocated for this queue pair. 123.It Va dev.nvme.0.ioq0.sq_head 124(R) Current location of the submission queue head pointer as observed by 125the driver. 126The head pointer is incremented by the controller as it takes commands off 127of the submission queue. 128.It Va dev.nvme.0.ioq0.sq_tail 129(R) Current location of the submission queue tail pointer as observed by 130the driver. 131The driver increments the tail pointer after writing a command 132into the submission queue to signal that a new command is ready to be 133processed. 134.It Va dev.nvme.0.ioq0.cq_head 135(R) Current location of the completion queue head pointer as observed by 136the driver. 137The driver increments the head pointer after finishing 138with a completion entry that was posted by the controller. 139.It Va dev.nvme.0.ioq0.num_cmds 140(R) Number of commands that have been submitted on this queue pair. 141.It Va dev.nvme.0.ioq0.dump_debug 142(W) Writing 1 to this sysctl will dump the full contents of the submission 143and completion queues to the console. 144.El 145.Sh SEE ALSO 146.Xr nvd 4 , 147.Xr pci 4 , 148.Xr nvmecontrol 8 , 149.Xr disk 9 . 150.Sh HISTORY 151The 152.Nm 153driver first appeared in 154.Fx 9.2. 155.Sh AUTHORS 156.An -nosplit 157The 158.Nm 159driver was developed by Intel and originally written by 160.An Jim Harris Aq jimharris@FreeBSD.org , 161with contributions from Joe Golio at EMC. 162.Pp 163This man page was written by 164.An Jim Harris Aq jimharris@FreeBSD.org . 165