1.\" 2.\" Copyright (c) 2016-2019 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 November 9, 2019 29.Dt NTB_TRANSPORT 4 30.Os 31.Sh NAME 32.Nm ntb_transport 33.Nd Packet-oriented transport 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.Ed 41.Pp 42Or, to load the driver as a module at boot, place the following line in 43.Xr loader.conf 5 : 44.Bd -literal -offset indent 45ntb_transport_load="YES" 46.Ed 47.Pp 48The following tunables are settable from the 49.Xr loader 8 : 50.Bl -ohang 51.It Va hw.ntb_transport.debug_level 52Driver debug level. 53The default value is 0, higher means more verbose. 54.It Va hw.ntb_transport.max_mw_size 55Limits maximum memory window usage. 56Allocation of big physically contiguous memory buffer may be a problem, 57while too big buffers makes no much sense for low latency network interface. 58.It Va hint.ntb_transport. Ns Ar X Ns Va .config 59Configures a set of the transport consumers, separated by commas. 60Each consumer can be configured as: "[<name>][:<queues>]", where: 61.Va name 62is a name of the driver to attach (empty means any), 63.Va queues 64is a number of queues to allocate (empty means automatic). 65The default configuration is empty string, which means single consumer 66with one queue per memory window, allowing any driver to attach. 67.It Va hint.ntb_transport. Ns Ar X Ns Va .compact 68Non-zero value enables compact version of scratchpad protocol, using half 69as many registers. 70Enabled automatically if there is not enough registers to negotiate all 71available memory windows. 72The compact version does not support memory windows of 4GB and above. 73.El 74.Sh DESCRIPTION 75The 76.Nm 77driver attaches on top of the 78.Nm ntb 79driver to utilize its resources to create a set of bidirectional queues, 80delivering packets between the systems. 81The primary purpose of this driver is to be used by 82.Nm if_ntb 83network interface, but other consumers may also be developed using KPI. 84.Pp 85Each 86.Nm 87require from underlying 88.Nm ntb 89instance: 90.Bl -bullet -compact 91.It 921 or more memory windows; 93.It 946 scratchpads, plus 2 more for each additional memory window, 95or 3 plus 1 in case of compact protocol; 96.It 971 doorbell for each memory window or configured queue. 98.El 99.Sh SEE ALSO 100.Xr if_ntb 4 , 101.Xr ntb 4 , 102.Xr ntb_hw_amd 4 , 103.Xr ntb_hw_intel 4 , 104.Xr ntb_hw_plx 4 105.Sh AUTHORS 106.An -nosplit 107The 108.Nm 109driver was developed by Intel and originally written by 110.An Carl Delsey Aq Mt carl@FreeBSD.org . 111Later improvements were done by 112.An Conrad E. Meyer Aq Mt cem@FreeBSD.org 113and 114.An Alexander Motin Aq Mt mav@FreeBSD.org . 115