101 lines
4.0 KiB
Groff
101 lines
4.0 KiB
Groff
.\"
|
|
.\" Copyright (c) 2016-2017 Alexander Motin <mav@FreeBSD.org>
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd October 11, 2020
|
|
.Dt NTB_HW_INTEL 4
|
|
.Os
|
|
.Sh NAME
|
|
.Nm ntb_hw_intel
|
|
.Nd Intel(R) Non-Transparent Bridge driver
|
|
.Sh SYNOPSIS
|
|
To compile this driver into your kernel,
|
|
place the following lines in your kernel configuration file:
|
|
.Bd -ragged -offset indent
|
|
.Cd "device ntb"
|
|
.Cd "device ntb_hw_intel"
|
|
.Ed
|
|
.Pp
|
|
Or, to load the driver as a module at boot, place the following line in
|
|
.Xr loader.conf 5 :
|
|
.Bd -literal -offset indent
|
|
ntb_hw_intel_load="YES"
|
|
.Ed
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm ntb_hw_intel
|
|
driver provides support for the Non-Transparent Bridge (NTB) hardware in
|
|
Intel Xeon E3/E5 and S1200 processor families, which allow one of their PCIe
|
|
ports to be switched from transparent to non-transparent bridge mode.
|
|
In this mode the bridge looks not like a PCI bridge, but like a PCI endpoint
|
|
device.
|
|
The driver hides hardware details, exposing memory windows, scratchpads
|
|
and doorbells of the other side via a hardware independent KPI to the
|
|
.Xr ntb 4
|
|
subsystem.
|
|
.Pp
|
|
The hardware provides 2 or 3 memory windows to the other system's memory,
|
|
16 scratchpad registers and 14, 31 or 34 doorbells to interrupt the other
|
|
system, depending on the platform.
|
|
On Xeon processors one of the memory windows is typically consumed by the driver
|
|
itself to work around multiple hardware errata.
|
|
.Sh CONFIGURATION
|
|
The NTB configuration should be set by BIOS.
|
|
It includes enabling NTB, choosing between NTB-to-NTB (back-to-back) or
|
|
NTB-to-Root Port mode,
|
|
enabling split BAR mode (one of two 64-bit BARs can be split into two 32-bit
|
|
ones) and configuring BAR sizes in bits (from 12 to 29/39) for both NTB sides.
|
|
.Pp
|
|
The recommended configuration is NTB-to-NTB mode, split bar enabled and
|
|
all BAR sizes set to 20 (1 MiB).
|
|
This needs to be done on both systems.
|
|
Note, on Xeon SkyLake and newer platforms, split bar mode is not available.
|
|
.Sh SEE ALSO
|
|
.Xr if_ntb 4 ,
|
|
.Xr ntb 4 ,
|
|
.Xr ntb_transport 4
|
|
.Sh AUTHORS
|
|
.An -nosplit
|
|
The
|
|
.Nm
|
|
driver was developed by Intel and originally written by
|
|
.An Carl Delsey Aq Mt carl@FreeBSD.org .
|
|
Later improvements were done by
|
|
.An Conrad E. Meyer Aq Mt cem@FreeBSD.org
|
|
and
|
|
.An Alexander Motin Aq Mt mav@FreeBSD.org .
|
|
.Sh BUGS
|
|
NTB-to-Root Port mode is not yet supported, but it doesn't look very useful.
|
|
.Pp
|
|
On Xeon v2/v3/v4 processors split BAR mode should be enabled to allow
|
|
SB01BASE_LOCKUP errata workaround to be applied by the driver.
|
|
.Pp
|
|
There is no way to protect your system from malicious behavior on the other
|
|
system once the link is brought up.
|
|
Anyone with root or kernel access on the other system can read or write to
|
|
any location on your system.
|
|
In other words, only connect two systems that completely trust each other.
|