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.Dd November 9, 2019 27.Dt NTB_TRANSPORT 4 28.Os 29.Sh NAME 30.Nm ntb_transport 31.Nd Packet-oriented transport for Non-Transparent Bridges 32.Sh SYNOPSIS 33To compile this driver into your kernel, 34place the following lines in your kernel configuration file: 35.Bd -ragged -offset indent 36.Cd "device ntb" 37.Cd "device ntb_transport" 38.Ed 39.Pp 40Or, to load the driver as a module at boot, place the following line in 41.Xr loader.conf 5 : 42.Bd -literal -offset indent 43ntb_transport_load="YES" 44.Ed 45.Pp 46The following tunables are settable from the 47.Xr loader 8 : 48.Bl -ohang 49.It Va hw.ntb_transport.debug_level 50Driver debug level. 51The default value is 0, higher means more verbose. 52.It Va hw.ntb_transport.max_mw_size 53Limits maximum memory window usage. 54Allocation of big physically contiguous memory buffer may be a problem, 55while too big buffers makes no much sense for low latency network interface. 56.It Va hint.ntb_transport. Ns Ar X Ns Va .config 57Configures a set of the transport consumers, separated by commas. 58Each consumer can be configured as: "[<name>][:<queues>]", where: 59.Va name 60is a name of the driver to attach (empty means any), 61.Va queues 62is a number of queues to allocate (empty means automatic). 63The default configuration is empty string, which means single consumer 64with one queue per memory window, allowing any driver to attach. 65.It Va hint.ntb_transport. Ns Ar X Ns Va .compact 66Non-zero value enables compact version of scratchpad protocol, using half 67as many registers. 68Enabled automatically if there is not enough registers to negotiate all 69available memory windows. 70The compact version does not support memory windows of 4GB and above. 71.El 72.Sh DESCRIPTION 73The 74.Nm 75driver attaches on top of the 76.Nm ntb 77driver to utilize its resources to create a set of bidirectional queues, 78delivering packets between the systems. 79The primary purpose of this driver is to be used by 80.Nm if_ntb 81network interface, but other consumers may also be developed using KPI. 82.Pp 83Each 84.Nm 85require from underlying 86.Nm ntb 87instance: 88.Bl -bullet -compact 89.It 901 or more memory windows; 91.It 926 scratchpads, plus 2 more for each additional memory window, 93or 3 plus 1 in case of compact protocol; 94.It 951 doorbell for each memory window or configured queue. 96.El 97.Sh SEE ALSO 98.Xr if_ntb 4 , 99.Xr ntb 4 , 100.Xr ntb_hw_amd 4 , 101.Xr ntb_hw_intel 4 , 102.Xr ntb_hw_plx 4 103.Sh AUTHORS 104.An -nosplit 105The 106.Nm 107driver was developed by Intel and originally written by 108.An Carl Delsey Aq Mt carl@FreeBSD.org . 109Later improvements were done by 110.An Conrad E. Meyer Aq Mt cem@FreeBSD.org 111and 112.An Alexander Motin Aq Mt mav@FreeBSD.org . 113