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 July 29, 2016 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 if_ntb" 39.Ed 40.Pp 41Or, to load the driver as a module at boot, place the following line in 42.Xr loader.conf 5 : 43.Bd -literal -offset indent 44if_ntb_load="YES" 45.Ed 46.Pp 47The following tunables are settable from the 48.Xr loader 8 : 49.Bl -ohang 50.It Va hw.if_ntb.num_queues 51Number of transport queues to use per interface. 52Default is unlimited. 53.El 54.Sh DESCRIPTION 55The 56.Nm 57driver attaches on top of the 58.Xr ntb_transport 4 59driver to utilize its resources to create virtual Ethernet interface between 60the systems. 61Interface capabilities depend on the underlying transport. 62Typical MTU is about 64KB to reduce overhead. 63By default one queue is used, but more may be configured. 64The MAC address for 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