1.\"- 2.\" SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3.\" 4.\" Copyright (c) 2021 Alexander Motin <mav@FreeBSD.org> 5.\" Copyright 2019 Cisco Systems, Inc. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" $FreeBSD$ 29.\" 30.Dd October 6, 2022 31.Dt VMD 4 32.Os 33.Sh NAME 34.Nm vmd 35.Nd Intel Volume Management Device driver 36.Sh SYNOPSIS 37To compile this driver into the kernel, place the following lines in your 38kernel configuration file: 39.Bd -ragged -offset -indent 40.Cd "device vmd" 41.Ed 42.Pp 43Alternatively, to load the driver as a module at boot time, place the following 44line in 45.Xr loader.conf 5 : 46.Bd -literal -offset indent 47vmd_load="YES" 48.Ed 49.Sh DESCRIPTION 50This driver attaches to Intel VMD devices, representing them as PCI-to-PCI 51bridges and providing access to children PCI devices via new PCI domains. 52Intel VMD is used by Intel's VROC (Virtual RAID on chip) to manage NVMe 53drives. 54.Sh LOADER TUNABLES 55The following tunables are settable via 56.Xr loader 8 57or 58.Xr sysctl 8 : 59.Bl -tag -width indent 60.It Va hw.vmd.bypass_msi 61By default all VMD devices remap children MSI/MSI-X interrupts into their 62own. It creates additional isolation, but also complicates things due to 63sharing, etc. Fortunately some VMD devices can bypass the remapping. 64Defaults to 1. 65.It Va hw.vmd.max_msi 66Limits number of Message Signaled Interrupt (MSI) vectors allowed to each 67child device. 68VMD can't distinguish MSI vectors of the same device, so there are no 69benefits to have more than one, unless it is required by specific device 70driver. 71Defaults to 1. 72.It Va hw.vmd.max_msix 73Limits number of Extended Message Signaled Interrupt (MSI-X) vectors 74allowed to each child device. 75VMD has limited number of interrupt vectors to map children interrupts into, 76so to avoid/reduce sharing children devices/drivers need to be constrained. 77Defaults to 3. 78.El 79.Sh SEE ALSO 80.Xr graid 8 81.Sh HISTORY 82The 83.Nm 84driver first appeared in 85.Fx 13.0 . 86