299 lines
11 KiB
Groff
299 lines
11 KiB
Groff
.\"
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.\" Copyright (c) 2014 Thomas Skibo <thomasskibo@yahoo.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. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission.
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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 26, 2014
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.Dt CGEM 4
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.Os
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.Sh NAME
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.Nm cgem
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.Nd "Cadence GEM Gigabit Ethernet driver"
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.Sh SYNOPSIS
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To compile this driver into the kernel,
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place the following lines in your
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kernel configuration file:
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.Bd -ragged -offset indent
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.Cd "device ether"
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.Cd "device miibus"
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.Cd "device cgem"
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.Ed
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.Sh DESCRIPTION
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The
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.Nm
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driver provides support for the Cadence GEM (Gigabit Ethernet MAC).
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The Cadence GEM is used in some SoC (System on a Chip) devices such as
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the Xilinx Zynq-7000 and the Atmel SAMA5D3.
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.Pp
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The
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.Nm
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driver supports the following media types:
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.Bl -tag -width ".Cm 10baseT/UTP"
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.It Cm autoselect
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Enable autoselection of the media type and options.
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The user can manually override
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the autoselected mode using
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.Xr ifconfig 8
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or by adding media options to
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.Xr rc.conf 5 .
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.It Cm 10baseT/UTP
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Set 10Mbps operation.
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The
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.Xr ifconfig 8
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.Cm mediaopt
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option can also be used to select either
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.Cm full-duplex
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or
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.Cm half-duplex
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modes.
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.It Cm 100baseTX
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Set 100Mbps (Fast Ethernet) operation.
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The
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.Xr ifconfig 8
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.Cm mediaopt
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option can also be used to select either
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.Cm full-duplex
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or
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.Cm half-duplex
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modes.
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.It Cm 1000baseT
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Set 1000Mbps (Gigabit Ethernet) operation over twisted pair.
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The GEM supports 1000Mbps in
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.Cm full-duplex
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mode only.
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.El
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.Pp
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The
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.Nm
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driver supports the following media options:
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.Bl -tag -width ".Cm full-duplex"
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.It Cm full-duplex
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Force full-duplex operation.
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.It Cm half-duplex
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Force half-duplex operation.
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.El
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.Pp
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The driver provides support for TCP/UDP/IP checksum offloading (although
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disabled by default).
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The device and driver also support 1536-byte frames for VLANs (vlanmtu).
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.Sh SYSCTL VARIABLES
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The following variables are available as both
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.Xr sysctl 8
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variables and
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.Xr loader 8
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tunables:
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.Bl -tag -width "xxxxxxxx"
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.It Va dev.cgem.%d.rxbufs
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The number of receive buffers allocated to the hardware.
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The default value is 256.
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The maximum value is 511.
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If this number is increased while the interface is UP, it will not
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take effect until the next packet is received.
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If this number is decreased while the interface is UP, buffers will
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not be immediately removed from the receive buffer ring but the
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number of buffers will decrease as packets are received until it
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reaches the new value.
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.It Va dev.cgem.%d.rxhangwar
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This tunable enables a work-around to recover from receive hangs.
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The default value is 1.
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Set to 0 to disable the work-around.
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.El
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.Pp
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The following read-only variables are available as
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.Xr sysctl 8
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variables:
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.Bl -tag -width "xxxxxxxx"
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.It Va dev.cgem.%d._rxoverruns
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This variable counts the number of receive packet buffer overrun interrupts.
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.It Va dev.cgem.%d._rxnobufs
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This variable counts the number of interrupts due to the GEM buffer ring
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going empty.
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.It Va dev.cgem.%d._rxdmamapfails
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This variable is the number of times bus_dmamap_load_mbuf_sg(9) failed in
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the receive path.
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.It Va dev.cgem.%d._txfull
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The number of times the GEM's transmit ring was full.
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.It Va dev.cgem.%d._txdmamapfails
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This variable is the number of times bus_dmamap_load_mbuf_sg(9) failed in
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the transmit path.
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.It Va dev.cgem.%d._txdefrags
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This variable is the number of times the driver needed to call m_defrag(9)
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because a packet queued for transmit had too many DMA segments.
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.It Va dev.cgem.%d._txdefragfails
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This variable is the number of times
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.Xr m_defrag 9
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failed.
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.It Va dev.cgem.%d.stats.*
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The following variables are useful MAC counters supplied by the hardware:
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.It Va dev.cgem.%d.stats.tx_bytes
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A 64-bit counter of the number of bytes transmitted in frames without error.
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.It Va dev.cgem.%d.stats.tx_frames
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Counter of frames transmitted without error excluding pause frames.
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.It Va dev.cgem.%d.stats.tx_frames_bcast
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Counter of broadcast frames transmitted without error excluding
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pause frames.
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.It Va dev.cgem.%d.stats.tx_frames_multi
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Counter of multicast frames transmitted without error excluding
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pause frames.
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.It Va dev.cgem.%d.stats.tx_frames_pause
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Counter of pause frames transmitted without error.
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.It Va dev.cgem.%d.stats.tx_frames_64b
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Counter of 64 byte frames transmitted without error.
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.It Va dev.cgem.%d.stats.tx_frames_65to127b
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Counter of 65 to 127 byte frames transmitted without error.
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.It Va dev.cgem.%d.stats.tx_frames_128to255b
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Counter of 128 to 255 byte frames transmitted without error.
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.It Va dev.cgem.%d.stats.tx_frames_256to511b
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Counter of 256 to 511 byte frames transmitted without error.
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.It Va dev.cgem.%d.stats.tx_frames_512to1023b
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Counter of 512 to 1023 byte frames transmitted without error.
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.It Va dev.cgem.%d.stats.tx_frames_1024to1536b
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Counter of 1024 to 1536 byte frames transmitted without error.
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.It Va dev.cgem.%d.stats.tx_under_runs
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Counter of frames not transmitted due to a transmit underrun.
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.It Va dev.cgem.%d.stats.tx_single_collisn
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Counter of frames experiencing a single collision before being successfully
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transmitted.
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.It Va dev.cgem.%d.stats.tx_multi_collisn
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Counter of frames experiencing between 2 and 15 collisions before
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being successfully transmitted.
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.It Va dev.cgem.%d.stats.tx_excsv_collisn
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Counter of frames that failed to transmit because they experienced 16
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collisions.
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.It Va dev.cgem.%d.stats.tx_late_collisn
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Counter of frames that experienced a late collision.
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.It Va dev.cgem.%d.stats.tx_deferred_frames
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Counter of frames experiencing deferral due to carrier sense being
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active on their first attempt at transmission.
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.It Va dev.cgem.%d.stats.tx_carrier_sense_errs
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Counter of frames transmitted where carrier sense was not seen during
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transmission or where carrier sense was deasserted after being asserted
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in a transmit frame without collision.
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.It Va dev.cgem.%d.stats.rx_bytes
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A 64-bit counter of bytes received without error excluding pause
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frames.
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.It Va dev.cgem.%d.stats.rx_frames
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Counter of frames received without error excluding pause frames.
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.It Va dev.cgem.%d.stats.rx_frames_bcast
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Counter of broadcast frames receive without error excluding pause frames.
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.It Va dev.cgem.%d.stats.rx_frames_multi
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Counter of multicast frames receive without error excluding pause frames.
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.It Va dev.cgem.%d.stats.rx_frames_pause
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Counter of pause frames recevied without error.
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.It Va dev.cgem.%d.stats.rx_frames_64b
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Counter of 64-byte frames received without error.
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.It Va dev.cgem.%d.stats.rx_frames_65to127b
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Counter of 65 to 127 byte frames received without error.
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.It Va dev.cgem.%d.stats.rx_frames_128to255b
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Counter of 128 to 255 byte frames received without error.
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.It Va dev.cgem.%d.stats.rx_frames_256to511b
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Counter of 256 to 511 byte frames received without error.
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.It Va dev.cgem.%d.stats.rx_frames_512to1023b
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Counter of 512 to 1023 byte frames received without error.
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.It Va dev.cgem.%d.stats.rx_frames_1024to1536b
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Counter of 1024 to 1536 byte frames received without error.
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.It Va dev.cgem.%d.stats.rx_frames_undersize
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Counter of frames received less than 64 bytes in length that
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do not also have either a CRC error or an alignment error.
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.It Va dev.cgem.%d.stats.rx_frames_oversize
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Counter of frames received exceeding 1536 bytes and do not also have either
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a CRC error or an alignment error.
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.It Va dev.cgem.%d.stats.rx_frames_jabber
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Counter of frames received exceeding 1536 bytes and also have either a CRC
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error, an alignment error, or a receive symbol error.
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.It Va dev.cgem.%d.stats.rx_frames_fcs_errs
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Counter of frames received with a bad CRC and are between 64
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and 1536 bytes.
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.It Va dev.cgem.%d.stats.rx_frames_length_errs
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Counter of frames received that are shorter than that extracted
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from the length field.
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.It Va dev.cgem.%d.stats.rx_symbol_errs
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Counter of receive symbol errors.
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.It Va dev.cgem.%d.stats.rx_align_errs
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Counter of received frames that are not an integral number of bytes.
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.It Va dev.cgem.%d.stats.rx_resource_errs
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Counter of frames successfully receive by the MAC but could not be
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copied to memory because no receive buffer was available.
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.It Va dev.cgem.%d.stats.rx_overrun_errs
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Counter of frames that are address recognized but were not copied
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to memory due to a receive overrun.
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.It Va dev.cgem.%d.stats.rx_frames_ip_hdr_csum_errs
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Counter of frames discarded due to an incorrect IP header checksum when
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checksum offloading is enabled.
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.It Va dev.cgem.%d.stats.rx_frames_tcp_csum_errs
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Counter of frames discarded due to an incorrect TCP checksum when
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checksum offloading is enabled.
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.It Va dev.cgem.%d.stats.rx_frames_udp_csum_errs
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Counter of frames discarded due to an incorrect UDP checksum when
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checksum offloading is enabled.
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.El
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.Sh SEE ALSO
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.Xr miibus 4 ,
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.Xr ifconfig 8
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.Rs
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.%T "Zynq-7000 SoC Technical Reference Manual (Xilinx doc UG585)"
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.%U http://www.xilinx.com/support/documentation/user_guides/\:ug585-Zynq-7000-TRM.pdf
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.Re
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.Sh HISTORY
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The
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.Nm
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device driver first appeared in
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.Fx 10.0 .
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.Sh AUTHORS
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The
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.Nm
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driver and this manual page was written by
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.An Thomas Skibo Aq Mt thomasskibo@yahoo.com .
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.Sh BUGS
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The GEM can perform TCP/UDP/IP checksum offloading.
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However, when transmit checksum offloading is enabled, the GEM generates and
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replaces checksums for all packets it transmits.
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In a system that is forwarding packets, the device could potentially correct
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the checksum of packet that was corrupted in transit.
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For this reason, checksum offloading is disabled by default but can be
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enabled using ifconfig(8).
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.Pp
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When receive checksum offloading is enabled, the device will discard packets
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with bad TCP/UDP/IP checksums.
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The bad packets will not be counted in any
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.Xr netstat 1
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statistics.
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There are
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.Xr sysctl 8
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variables that count
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packets discarded by the hardware (see below).
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.Pp
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The GEM used in the Zynq-7000 has a bug such that the receiver can
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potentially freeze up under a high load.
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The issue is described in sec. 16.7
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"Known Issues" of the Zynq-7000 SoC Technical Reference Manual (Xilinx
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UG585 v1.7).
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The
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.Nm
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driver implements the work-around suggested in the manual.
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If the bug does not exist in other versions of this device, the
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work-around can be disabled by setting the dev.cgem.%d.rxhangwar
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.Xr sysctl 8
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variable to 0.
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