95 lines
3.5 KiB
Groff
95 lines
3.5 KiB
Groff
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.\"
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.\" Copyright (c) 2019 Rajesh Kumar <rajesh1.kumar@amd.com>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd August 29, 2019
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.Dt NTB_HW_AMD 4
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.Os
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.Sh NAME
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.Nm ntb_hw_amd
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.Nd AMD Non-Transparent Bridge driver
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.Sh SYNOPSIS
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To compile this driver into your kernel,
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place the following lines in your kernel configuration file:
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.Bd -ragged -offset indent
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.Cd "device ntb"
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.Cd "device ntb_hw_amd"
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.Ed
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.Pp
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Or, to load the driver as a module at boot, place the following line in
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.Xr loader.conf 5 :
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.Bd -literal -offset indent
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ntb_hw_amd_load="YES"
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.Ed
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.Pp
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The following sysctls are supported in this driver
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.Bl -ohang
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.It Va dev.ntb_hw.X.info
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Reading this sysctl will give the basic details like the number of memory
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windows, scratchpads and doorbells exposed by the NTB on the local host to
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access the devices beyond the bridge.
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It also provides details about the masked doorbells, translation address and
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size limit of each exposed memory window and link status information.
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.El
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.Sh DESCRIPTION
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The
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.Nm ntb_hw_amd
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driver provides support for the Non-Transparent Bridge (NTB) hardware in
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AMD EPYC processor family.
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The Non-Transparent Bridge does not look as a regular PCI bridge, but as PCI
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endpoint device, hiding the devices behind it.
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The driver hides details of hardware on the other side, but exposes memory windows,
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scratchpads and doorbells to access the other side via hardware independent
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KPI to
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.Xr ntb 4
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subsystem.
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.Pp
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The hardware provides 2 (both 64-bit) or 3 (one 32-bit and two 64-bit) memory
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windows to the other system's memory, up to 16 scratchpad registers and 16
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doorbells to communicate with and interrupt the other system respectively.
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.Sh CONFIGURATION
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The NTB configuration should be set by BIOS.
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This includes enabling NTB, choosing topology (only NTB-to-Root Port
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mode is supported now), role of the host in the topology.
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This needs to be done on both systems.
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.Pp
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The BAR size for memory windows is configured to 1 MiB by default.
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.Sh SEE ALSO
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.Xr if_ntb 4 ,
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.Xr ntb 4 ,
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.Xr ntb_transport 4
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.Sh AUTHORS
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.An -nosplit
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The
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.Nm
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driver was developed by AMD and originally written by
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.An Rajesh Kumar Aq Mt rajesh1.kumar@amd.com .
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Reviewed by
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.An Alexander Motin Aq Mt mav@FreeBSD.org ,
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.An Conrad E. Meyer Aq Mt cem@FreeBSD.org
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and
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.An Warner Losh Aq Mt imp@FreeBSD.org .
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