1.\" 2.\" Copyright (c) 2016 Alexander Motin <mav@FreeBSD.org> 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.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD$ 27.\" 28.Dd September 2, 2017 29.Dt IF_NTB 4 30.Os 31.Sh NAME 32.Nm if_ntb 33.Nd Virtual Ethernet interface for Non-Transparent Bridges 34.Sh SYNOPSIS 35To compile this driver into your kernel, 36place the following lines in your kernel configuration file: 37.Bd -ragged -offset indent 38.Cd "device ntb" 39.Cd "device ntb_transport" 40.Cd "device if_ntb" 41.Ed 42.Pp 43Or, to load the driver as a module at boot, place the following line in 44.Xr loader.conf 5 : 45.Bd -literal -offset indent 46if_ntb_load="YES" 47.Ed 48.Pp 49The following tunables are settable from the 50.Xr loader 8 : 51.Bl -ohang 52.It Va hw.if_ntb.num_queues 53Limits maximal number of queues per interface. 54Default is unlimited. 55.El 56.Sh DESCRIPTION 57The 58.Nm 59driver attaches on top of the 60.Xr ntb_transport 4 61driver to utilize one or more of its packet queues to create virtual 62Ethernet network interface between the systems. 63Typical MTU for the interface is about 64KB to reduce overhead. 64Default MAC address for the interface is randomly generated. 65.Pp 66The 67.Nm 68driver does not implement any real hardware offload, but since PCIe link is 69protected by CRC32, in some situations it may be possible to save some CPU 70cycles by enabling fake checksum offload on both link sides via setting 71.Cm rxcsum 72and 73.Cm txcsum 74interface options. 75.Sh SEE ALSO 76.Xr ntb_transport 4 77.Sh AUTHORS 78.An -nosplit 79The 80.Nm 81driver was developed by Intel and originally written by 82.An Carl Delsey Aq Mt carl@FreeBSD.org . 83Later improvements were done by 84.An Conrad E. Meyer Aq Mt cem@FreeBSD.org 85and 86.An Alexander Motin Aq Mt mav@FreeBSD.org . 87.Sh BUGS 88Linux supports only one queue per interface, so manual configuration 89may be required for compatibility. 90