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.\" $FreeBSD$ 27.\" 28.Dd August 29, 2019 29.Dt NTB 4 30.Os 31.Sh NAME 32.Nm ntb 33.Nd Non-Transparent Bridge subsystem 34.Sh SYNOPSIS 35To compile it into your kernel, 36place the following lines in your kernel configuration file: 37.Bd -ragged -offset indent 38.Cd "device ntb" 39.Ed 40.Pp 41Or, to load it as a module at boot, place the following line in 42.Xr loader.conf 5 : 43.Bd -literal -offset indent 44ntb_load="YES" 45.Ed 46.Pp 47The following tunables are settable from the 48.Xr loader 8 : 49.Bl -ohang 50.It Va hw.ntb.debug_level 51Driver debug level. 52The default value is 0, higher means more verbose. 53.It Va hint.ntb_hw. Ns Ar X Ns Va .config 54Configures a set of NTB functions, separated by commas, 55and their resource allocation. 56Each function can be configured as: "[<name>][:<mw>[:<spad>[:<db>]]]", where: 57.Va name 58is a name of the driver to attach (empty means any), 59.Va mw 60is a number of memory windows to allocate (empty means all available), 61.Va spad 62is a number of scratchpad registers to allocate (empty means all available), 63.Va db 64is a number of doorbells to allocate (empty means all available). 65The default configuration is empty string, which means single function 66with all available resources, allowing any driver to attach. 67.El 68.Sh DESCRIPTION 69Non-Transparent Bridges connect two computer systems with PCIe 70link(s), providing each of them limited access to others memory space, 71scratchpad registers and interrupts. 72The 73.Nm 74subsystem uses those resources provided in generic way by hardware drivers 75and splits them between several functions, according to specified 76configuration. 77.Sh SEE ALSO 78.Xr if_ntb 4 , 79.Xr ntb_hw_amd 4 , 80.Xr ntb_hw_intel 4 , 81.Xr ntb_hw_plx 4 , 82.Xr ntb_transport 4 83.Sh AUTHORS 84.An -nosplit 85The 86.Nm 87subsystem was developed by Intel and originally written by 88.An Carl Delsey Aq Mt carl@FreeBSD.org . 89Later improvements were done by 90.An Conrad E. Meyer Aq Mt cem@FreeBSD.org 91and 92.An Alexander Motin Aq Mt mav@FreeBSD.org . 93