115 lines
3.9 KiB
Groff
115 lines
3.9 KiB
Groff
.\"
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.\" Copyright (c) 2016-2019 Alexander Motin <mav@FreeBSD.org>
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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 November 9, 2019
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.Dt NTB_TRANSPORT 4
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.Os
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.Sh NAME
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.Nm ntb_transport
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.Nd Packet-oriented transport for Non-Transparent Bridges
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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_transport"
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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_transport_load="YES"
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.Ed
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.Pp
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The following tunables are settable from the
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.Xr loader 8 :
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.Bl -ohang
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.It Va hw.ntb_transport.debug_level
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Driver debug level.
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The default value is 0, higher means more verbose.
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.It Va hw.ntb_transport.max_mw_size
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Limits maximum memory window usage.
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Allocation of big physically contiguous memory buffer may be a problem,
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while too big buffers makes no much sense for low latency network interface.
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.It Va hint.ntb_transport. Ns Ar X Ns Va .config
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Configures a set of the transport consumers, separated by commas.
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Each consumer can be configured as: "[<name>][:<queues>]", where:
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.Va name
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is a name of the driver to attach (empty means any),
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.Va queues
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is a number of queues to allocate (empty means automatic).
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The default configuration is empty string, which means single consumer
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with one queue per memory window, allowing any driver to attach.
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.It Va hint.ntb_transport. Ns Ar X Ns Va .compact
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Non-zero value enables compact version of scratchpad protocol, using half
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as many registers.
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Enabled automatically if there is not enough registers to negotiate all
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available memory windows.
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The compact version does not support memory windows of 4GB and above.
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.El
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.Sh DESCRIPTION
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The
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.Nm
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driver attaches on top of the
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.Nm ntb
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driver to utilize its resources to create a set of bidirectional queues,
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delivering packets between the systems.
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The primary purpose of this driver is to be used by
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.Nm if_ntb
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network interface, but other consumers may also be developed using KPI.
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.Pp
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Each
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.Nm
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require from underlying
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.Nm ntb
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instance:
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.Bl -bullet -compact
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.It
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1 or more memory windows;
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.It
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6 scratchpads, plus 2 more for each additional memory window,
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or 3 plus 1 in case of compact protocol;
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.It
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1 doorbell for each memory window or configured queue.
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.El
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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_hw_amd 4 ,
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.Xr ntb_hw_intel 4 ,
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.Xr ntb_hw_plx 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 Intel and originally written by
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.An Carl Delsey Aq Mt carl@FreeBSD.org .
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Later improvements were done by
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.An Conrad E. Meyer Aq Mt cem@FreeBSD.org
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and
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.An Alexander Motin Aq Mt mav@FreeBSD.org .
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