1.\"- 2.\" SPDX-License-Identifier: BSD-2-Clause 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.Dd October 6, 2022 29.Dt VMD 4 30.Os 31.Sh NAME 32.Nm vmd 33.Nd Intel Volume Management Device driver 34.Sh SYNOPSIS 35To compile this driver into the kernel, place the following lines in your 36kernel configuration file: 37.Bd -ragged -offset indent 38.Cd "device vmd" 39.Ed 40.Pp 41Alternatively, to load the driver as a module at boot time, place the following 42line in 43.Xr loader.conf 5 : 44.Bd -literal -offset indent 45vmd_load="YES" 46.Ed 47.Sh DESCRIPTION 48This driver attaches to Intel VMD devices, representing them as PCI-to-PCI 49bridges and providing access to children PCI devices via new PCI domains. 50Intel VMD is used by Intel's VROC (Virtual RAID on chip) to manage NVMe 51drives. 52.Sh LOADER TUNABLES 53The following tunables are settable via 54.Xr loader 8 55or 56.Xr sysctl 8 : 57.Bl -tag -width indent 58.It Va hw.vmd.bypass_msi 59By default all VMD devices remap children MSI/MSI-X interrupts into their 60own. It creates additional isolation, but also complicates things due to 61sharing, etc. Fortunately some VMD devices can bypass the remapping. 62Defaults to 1. 63.It Va hw.vmd.max_msi 64Limits number of Message Signaled Interrupt (MSI) vectors allowed to each 65child device. 66VMD can't distinguish MSI vectors of the same device, so there are no 67benefits to have more than one, unless it is required by specific device 68driver. 69Defaults to 1. 70.It Va hw.vmd.max_msix 71Limits number of Extended Message Signaled Interrupt (MSI-X) vectors 72allowed to each child device. 73VMD has limited number of interrupt vectors to map children interrupts into, 74so to avoid/reduce sharing children devices/drivers need to be constrained. 75Defaults to 3. 76.El 77.Sh SEE ALSO 78.Xr graid 8 79.Sh HISTORY 80The 81.Nm 82driver first appeared in 83.Fx 13.0 . 84