.\" Copyright (c) 2008 Pyun YongHyeon
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.\" $FreeBSD: src/share/man/man4/jme.4,v 1.1 2008/05/27 01:59:17 yongari Exp $
.\"
.Dd November 28, 2014
.Dt JME 4
.Os
.Sh NAME
.Nm jme
.Nd JMicron Gigabit/Fast Ethernet driver
.Sh SYNOPSIS
To compile this driver into the kernel,
place the following lines in your
kernel configuration file:
.Bd -ragged -offset indent
.Cd "device miibus"
.Cd "device jme"
.Ed
.Pp
Alternatively, to load the driver as a
module at boot time, place the following line in
.Xr loader.conf 5 :
.Bd -literal -offset indent
if_jme_load="YES"
.Ed
.Sh DESCRIPTION
The
.Nm
device driver provides support for JMicron JMC250 PCI Express
Gigabit Ethernet controllers and JMicron JMC260 PCI Express Fast
Ethernet controllers.
.Pp
All LOMs supported by the
.Nm
driver have TCP/UDP/IP checksum offload for both transmit and receive,
TCP segmentation offload (TSO),
receive side scaling (RSS),
multiple vector MSI-X,
hardware VLAN tag stripping/insertion features,
.\" Wake On Lan (WOL)
an interrupt coalescing/moderation mechanism as well as
a 64-bit multicast hash filter.
Up to 4 reception queues can be enabled.
By default, the
.Nm
driver will try enabling as many reception queues as allowed by
the number of CPUs in the system.
.Pp
The JMC250 also supports Jumbo Frames (up to 9216 bytes), which can be
configured via the interface MTU setting.
Selecting an MTU larger than 1500 bytes with the
.Xr ifconfig 8
utility configures the adapter to receive and transmit Jumbo Frames.
.Pp
The
.Nm
driver supports the following media types:
.Bl -tag -width ".Cm 10baseT/UTP"
.It Cm autoselect
Enable autoselection of the media type and options.
The user can manually override
the autoselected mode by adding media options to
.Xr rc.conf 5 .
.It Cm 10baseT/UTP
Set 10Mbps operation.
.It Cm 100baseTX
Set 100Mbps (Fast Ethernet) operation.
.It Cm 1000baseT
Set 1000baseT operation over twisted pair.
.El
.Pp
The
.Nm
driver supports the following media options:
.Bl -tag -width ".Cm full-duplex"
.It Cm full-duplex
Force full duplex operation.
.It Cm half-duplex
Force half duplex operation.
.El
.Pp
For more information on configuring this device, see
.Xr ifconfig 8 .
The
.Nm
driver supports
.Xr polling 4 .
.Ss Loader Tunables
By default, the driver will use MSI-X if it is supported.
This behavior can be turned off by setting the following tunable:
.Em ( X
is the device unit number):
.Bd -literal -offset indent
hw.jme.msix.enable=0
hw.jmeX.msix.enable=0
.Ed
.Pp
If MSI-X is used,
the transmission queue MSI-X's target CPU
can be specified using the following tunable:
.Bd -literal -offset indent
hw.jmeX.msix.txoff
.Ed
.Pp
The maximum allowed value for this tunable is
the power of 2 number of CPUs minus one.
.Pp
If MSI-X is used,
the reception queue MSI-Xs' leading target CPU
can be specified using the following tunable:
.Bd -literal -offset indent
hw.jmeX.msix.rxoff
.Ed
.Pp
The value specificed must be aligned to the number of reception queues enabled
and must be less than the power of 2 number of CPUs.
.Pp
If MSI-X is disabled,
the driver will use MSI if it is supported.
This behavior can be turned off by setting the following tunable:
.Bd -literal -offset indent
hw.jme.msi.enable=0
hw.jmeX.msi.enable=0
.Ed
.Pp
If MSI is used,
MSI's target CPU can be changed by the following tunable:
.Bd -literal -offset indent
hw.jmeX.msi.cpu
.Ed
.Pp
The maximum allowed value for this tunable is the number of CPUs minus one.
.Pp
Number of reception queues that can be enabled:
.Bd -literal -offset indent
hw.jme.rx_ring_count
hw.jmeX.rx_ring_count
.Ed
.Pp
Maximum allowed value for these tunables is 4
and it must be power of 2 aligned.
Setting these tunables to 0 allows driver to enable as many reception queues
as allowed by the number of CPUs.
.Pp
Number of reception descriptors that can be used:
.Bd -literal -offset indent
hw.jme.rx_desc_count
hw.jmeX.rx_desc_count
.Ed
.Pp
Maximum allowed value for these tunables is 1024.
.Pp
Number of transmission descriptors that can be used:
.Bd -literal -offset indent
hw.jme.tx_desc_count
hw.jmeX.tx_desc_count
.Ed
.Pp
Maximum allowed value for these tunables is 1024.
.Pp
.Xr polling 4
reception queues' leading target CPU can be specified by the following tunable:
.Bd -literal -offset indent
hw.jmeX.npoll.rxoff
.Ed
.Pp
The value specificed must be aligned to the number of reception queues enabled
and must be less than the power of 2 number of CPUs.
.Pp
.Xr polling 4
transmission queue's target CPU can be specified by the following tunable:
.Bd -literal -offset indent
hw.jmeX.npoll.txoff
.Ed
.Pp
The maximum allowed value for this tunable is
the power of 2 number of CPUs minus one.
.Ss MIB Variables
A number of per-interface variables are implemented in the
.Va dev.jme. Ns Em X
branch of the
.Xr sysctl 3
MIB.
.Bl -tag -width "rx_ring_count"
.It Va tx_coal_to
Maximum amount of time to delay for TX completion interrupt in
units of 1us.
The accepted range is 1 to 65535, the default is 250 (250us).
.It Va tx_coal_pkt
Maximum number of packets to fire TX completion interrupt.
The accepted range is 0 to 255, the default is 128.
Packet count based TX interrupt coalescing could be disabled
by setting this variable to 0.
.It Va rx_coal_to
Maximum amount of time to delay for RX completion interrupt in
units of 1us.
The accepted range is 1 to 65535, the default is 150 (150us).
.It Va rx_coal_pkt
Maximum number of packets to fire RX completion interrupt.
The accepted range is 0 to 255, the default is 64.
Packet count based RX interrupt coalescing could be disabled
by setting this variable to 0.
.It Va rx_desc_count
Number of RX descriptors per-ring (read-only).
Use the tunable
.Va hw.jme.rx_desc_count
to configure it.
.It Va tx_desc_count
Number of TX descriptors (read-only).
Use the tunable
.Va hw.jme.tx_desc_count
to configure it.
.It Va rx_ring_count
Number of RX rings (read-only).
Use the tunable
.Va hw.jme.rx_ring_count
to configure it.
.It Va tx_wreg
The number of transmission descriptors should be setup
before the hardware register is written.
Setting this value too high will have negative effect on
transmission timeliness.
Setting this value too low will hurt overall transmission
due to the frequent hardware register writing.
.It Va npoll_rxoff
.Xr polling 4
reception queues' leading target CPU.
It has the same constraints as the tunable
.Va hw.jmeX.npoll.rxoff .
The set value will take effect the next time
.Xr polling 4
is enabled on the device.
.It Va npoll_txoff
.Xr polling 4
transmission queue's target CPU.
It has the same constraints as the tunable
.Va hw.jmeX.npoll.txoff .
The set value will take effect the next time
.Xr polling 4
is enabled on the device.
.El
.Sh SEE ALSO
.Xr altq 4 ,
.Xr arp 4 ,
.Xr ifmedia 4 ,
.Xr miibus 4 ,
.Xr netintro 4 ,
.Xr ng_ether 4 ,
.Xr polling 4 ,
.Xr vlan 4 ,
.Xr ifconfig 8
.Sh HISTORY
The
.Nm
driver was written by
.An Pyun YongHyeon Aq Mt yongari@FreeBSD.org .
It first appeared in
.Fx 7.1
and was imported into
.Dx 2.1 .
.An Sepherosa Ziehau
added the receive side scaling and
multiple vector MSI-X support to
.Dx .