1.\" 2.\" Copyright (c) 2017 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 August 29, 2019 27.Dt NTB 4 28.Os 29.Sh NAME 30.Nm ntb 31.Nd Non-Transparent Bridge subsystem 32.Sh SYNOPSIS 33To compile it into your kernel, 34place the following lines in your kernel configuration file: 35.Bd -ragged -offset indent 36.Cd "device ntb" 37.Ed 38.Pp 39Or, to load it as a module at boot, place the following line in 40.Xr loader.conf 5 : 41.Bd -literal -offset indent 42ntb_load="YES" 43.Ed 44.Pp 45The following tunables are settable from the 46.Xr loader 8 : 47.Bl -ohang 48.It Va hw.ntb.debug_level 49Driver debug level. 50The default value is 0, higher means more verbose. 51.It Va hint.ntb_hw. Ns Ar X Ns Va .config 52Configures a set of NTB functions, separated by commas, 53and their resource allocation. 54Each function can be configured as: "[<name>][:<mw>[:<spad>[:<db>]]]", where: 55.Va name 56is a name of the driver to attach (empty means any), 57.Va mw 58is a number of memory windows to allocate (empty means all available), 59.Va spad 60is a number of scratchpad registers to allocate (empty means all available), 61.Va db 62is a number of doorbells to allocate (empty means all available). 63The default configuration is empty string, which means single function 64with all available resources, allowing any driver to attach. 65.El 66.Sh DESCRIPTION 67Non-Transparent Bridges connect two computer systems with PCIe 68link(s), providing each of them limited access to others memory space, 69scratchpad registers and interrupts. 70The 71.Nm 72subsystem uses those resources provided in generic way by hardware drivers 73and splits them between several functions, according to specified 74configuration. 75.Sh SEE ALSO 76.Xr if_ntb 4 , 77.Xr ntb_hw_amd 4 , 78.Xr ntb_hw_intel 4 , 79.Xr ntb_hw_plx 4 , 80.Xr ntb_transport 4 81.Sh AUTHORS 82.An -nosplit 83The 84.Nm 85subsystem was developed by Intel and originally written by 86.An Carl Delsey Aq Mt carl@FreeBSD.org . 87Later improvements were done by 88.An Conrad E. Meyer Aq Mt cem@FreeBSD.org 89and 90.An Alexander Motin Aq Mt mav@FreeBSD.org . 91