1.\" 2.\" Copyright (c) 2019 Rajesh Kumar <rajesh1.kumar@amd.com> 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_HW_AMD 4 28.Os 29.Sh NAME 30.Nm ntb_hw_amd 31.Nd AMD Non-Transparent Bridge driver 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_hw_amd" 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_hw_amd_load="YES" 44.Ed 45.Pp 46The following sysctls are supported in this driver 47.Bl -ohang 48.It Va dev.ntb_hw.X.info 49Reading this sysctl will give the basic details like the number of memory 50windows, scratchpads and doorbells exposed by the NTB on the local host to 51access the devices beyond the bridge. 52It also provides details about the masked doorbells, translation address and 53size limit of each exposed memory window and link status information. 54.El 55.Sh DESCRIPTION 56The 57.Nm ntb_hw_amd 58driver provides support for the Non-Transparent Bridge (NTB) hardware in 59AMD EPYC processor family. 60The Non-Transparent Bridge does not look as a regular PCI bridge, but as PCI 61endpoint device, hiding the devices behind it. 62The driver hides details of hardware on the other side, but exposes memory windows, 63scratchpads and doorbells to access the other side via hardware independent 64KPI to 65.Xr ntb 4 66subsystem. 67.Pp 68The hardware provides 2 (both 64-bit) or 3 (one 32-bit and two 64-bit) memory 69windows to the other system's memory, up to 16 scratchpad registers and 16 70doorbells to communicate with and interrupt the other system respectively. 71.Sh CONFIGURATION 72The NTB configuration should be set by BIOS. 73This includes enabling NTB, choosing topology (only NTB-to-Root Port 74mode is supported now), role of the host in the topology. 75This needs to be done on both systems. 76.Pp 77The BAR size for memory windows is configured to 1 MiB by default. 78.Sh SEE ALSO 79.Xr if_ntb 4 , 80.Xr ntb 4 , 81.Xr ntb_transport 4 82.Sh AUTHORS 83.An -nosplit 84The 85.Nm 86driver was developed by AMD and originally written by 87.An Rajesh Kumar Aq Mt rajesh1.kumar@amd.com . 88Reviewed by 89.An Alexander Motin Aq Mt mav@FreeBSD.org , 90.An Conrad E. Meyer Aq Mt cem@FreeBSD.org 91and 92.An Warner Losh Aq Mt imp@FreeBSD.org . 93