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.\" $FreeBSD$ 27.\" 28.Dd August 29, 2019 29.Dt NTB_HW_AMD 4 30.Os 31.Sh NAME 32.Nm ntb_hw_amd 33.Nd AMD Non-Transparent Bridge driver 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_hw_amd" 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_hw_amd_load="YES" 46.Ed 47.Pp 48The following sysctls are supported in this driver 49.Bl -ohang 50.It Va dev.ntb_hw.X.info 51Reading this sysctl will give the basic details like the number of memory 52windows, scratchpads and doorbells exposed by the NTB on the local host to 53access the devices beyond the bridge. 54It also provides details about the masked doorbells, translation address and 55size limit of each exposed memory window and link status information. 56.El 57.Sh DESCRIPTION 58The 59.Nm ntb_hw_amd 60driver provides support for the Non-Transparent Bridge (NTB) hardware in 61AMD EPYC processor family. 62The Non-Transparent Bridge does not look as a regular PCI bridge, but as PCI 63endpoint device, hiding the devices behind it. 64The driver hides details of hardware on the other side, but exposes memory windows, 65scratchpads and doorbells to access the other side via hardware independent 66KPI to 67.Xr ntb 4 68subsystem. 69.Pp 70The hardware provides 2 (both 64-bit) or 3 (one 32-bit and two 64-bit) memory 71windows to the other system's memory, up to 16 scratchpad registers and 16 72doorbells to communicate with and interrupt the other system respectively. 73.Sh CONFIGURATION 74The NTB configuration should be set by BIOS. 75This includes enabling NTB, choosing topology (only NTB-to-Root Port 76mode is supported now), role of the host in the topology. 77This needs to be done on both systems. 78.Pp 79The BAR size for memory windows is configured to 1 MiB by default. 80.Sh SEE ALSO 81.Xr if_ntb 4 , 82.Xr ntb 4 , 83.Xr ntb_transport 4 84.Sh AUTHORS 85.An -nosplit 86The 87.Nm 88driver was developed by AMD and originally written by 89.An Rajesh Kumar Aq Mt rajesh1.kumar@amd.com . 90Reviewed by 91.An Alexander Motin Aq Mt mav@FreeBSD.org , 92.An Conrad E. Meyer Aq Mt cem@FreeBSD.org 93and 94.An Warner Losh Aq Mt imp@FreeBSD.org . 95