man/man4/em.4

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.\" $FreeBSD: src/share/man/man4/em.4,v 1.30 2008/10/06 21:55:53 simon Exp $
.\"
.Dd September 4, 2013
.Dt EM 4
.Os
.Sh NAME
.Nm em ,
.Nm emx
.Nd "Intel(R) PRO/1000 Gigabit Ethernet adapter 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 ig_hal"
.Cd "device em  # for em(4)"
.Cd "device emx # for emx(4)"
.Ed
.Pp
Alternatively, to load the driver as a
module at boot time, place the following lines in
.Xr loader.conf 5 :
.Bd -literal -offset indent
ig_hal_load="YES"
if_em_load="YES"  # for em(4)
if_emx_load="YES" # for emx(4)
.Ed
.Sh DESCRIPTION
The
.Nm
driver provides support for PCI Gigabit Ethernet adapters based on
the Intel 82540, 82541ER, 82541PI, 82542, 82543, 82544, 82545, 82546,
82546EB, 82546GB, 82547, 82571, 81572, 82573, 82574, I217 and I218
Ethernet controller chips.
The driver supports Transmit/Receive checksum offload
and Jumbo Frames on all but 82542-based adapters.
Furthermore it supports TCP segmentation offload (TSO) on PCI-E adapters.
.Pp
The
.Nm emx
is a version of the
.Nm em
driver for 82571, 82572, 82573, 82574, I217 and I218 Ethernet controller chips
that additionally supports Receive Side Scaling (RSS, 2 reception queues).
By default,
the
.Nm emx
driver will try enabling 2 reception queues
if there are multiple CPUs on the system.
For 82571 and 82572,
the
.Nm emx
driver could be configured to enable 2 transmission queues.
By default,
the
.Nm emx
driver only enables 1 transmission queue,
since enabling 2 transmission queues will require setting up context
descriptor for every packets requiring hardware transmission offloading,
which hurts tiny packet transmission performance.
However,
if the workload is mainly bulk data
or hardware transmission offloading is rarely required,
extra transmission queue could be enabled to reduce contention on
transmission path.
2 transmission queues will only be used when
.Xr polling 4
is enabled on the device.
If multiple transmission queues are used,
the round-robin arbitration is performed among the transmission queues.
It should be noted that
if both TSO and multiple transmission queues are used,
the round-robin arbitration between transmission queues is done
at the TSO packet boundary.
.Pp
.\"For questions related to hardware requirements,
.\"refer to the documentation supplied with your Intel PRO/1000 adapter.
.\"All hardware requirements listed apply to use with
.\".Dx .
.\".Pp
Support for Jumbo Frames is provided 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.
The maximum MTU size for Jumbo Frames is 16114.
.Pp
This driver version supports VLANs.
The
.Nm
and
.Nm emx
drivers support the following media types:
.Bl -tag -width ".Cm 10baseT/UTP"
.It Cm autoselect
Enables auto-negotiation for speed and duplex.
.It Cm 10baseT/UTP
Sets 10Mbps operation.
Use the
.Cm mediaopt
option to select
.Cm full-duplex
mode.
.It Cm 100baseTX
Sets 100Mbps operation.
Use the
.Cm mediaopt
option to select
.Cm full-duplex
mode.
.It Cm 1000baseSX
Sets 1000Mbps operation.
Only
.Cm full-duplex
mode is supported at this speed.
.It Cm 1000baseT
Sets 1000Mbps operation.
Only
.Cm full-duplex
mode is supported at this speed.
.El
.Pp
The
.Nm
and
.Nm emx
drivers support the following media options:
.Bl -tag -width ".Cm full-duplex"
.It Cm full-duplex
Forces full-duplex operation
.It Cm half-duplex
Forces half-duplex operation.
.El
.Pp
Only use
.Cm mediaopt
to set the driver to
.Cm full-duplex .
If
.Cm mediaopt
is not specified, the driver defaults to
.Cm half-duplex .
.Pp
For more information on configuring this device, see
.Xr ifconfig 8 .
.Pp
The
.Nm
and
.Nm emx
drivers support
.Xr polling 4 .
.Sh HARDWARE
The
.Nm
driver supports Gigabit Ethernet adapters based on the Intel
82540, 82541ER, 82541PI, 82542, 82543, 82544, 82545, 82546, 82546EB,
82546GB, 82547, 82571, 82572, 82573, 82574, I217 and I218
controller chips:
.Pp
.Bl -bullet -compact
.It
Intel 82540EM Gigabit Ethernet Controller
.It
Intel 82540EP Gigabit Ethernet Controller
.It
Intel 82543GC Gigabit Ethernet Controller
.It
Intel 82544 Gigabit Ethernet Controller
.It
Intel 82544EI Gigabit Ethernet Controller
.It
Intel 82545GM Gigabit Ethernet Controller
.It
Intel 82546EB Gigabit Ethernet Controller
.It
Intel 82547EI Gigabit Ethernet Controller
.It
Intel 82547GI Gigabit Ethernet Controller
.It
Intel 82567 Gigabit Ethernet Controller
.It
Intel 82571EB Gigabit Ethernet Controller
.It
Intel 82572EI Gigabit Ethernet Controller
.It
Intel 82573E Gigabit Ethernet Controller
.It
Intel 82573L Gigabit Ethernet Controller
.It
Intel 82573V Gigabit Ethernet Controller
.It
Intel 82574 Gigabit Ethernet Controller
.It
Intel 82578 Gigabit Ethernet PHY
.It
Intel 82579 Gigabit Ethernet Controller
.It
Intel Ethernet Connection I217-LM
.It
Intel Ethernet Connection I217-V
.It
Intel Ethernet Connection I218-LM
.It
Intel Ethernet Connection I218-V
.It
Intel Gigabit CT Desktop Adapter
.It
Intel PRO/1000 F Server Adapter
.It
Intel PRO/1000 GT Quad Port Server Adapter
.It
Intel PRO/1000 MF Dual Port Server Adapter
.It
Intel PRO/1000 MF Server Adapter
.It
Intel PRO/1000 MF Server Adapter (LX)
.It
Intel PRO/1000 MT Dual Port Server Adapter
.It
Intel PRO/1000 MT Quad Port Server Adapter
.It
Intel PRO/1000 MT Server Adapter
.It
Intel PRO/1000 PF Dual Port Server Adapter
.It
Intel PRO/1000 PF Quad Port Server Adapter
.It
Intel PRO/1000 PF Server Adapter
.It
Intel PRO/1000 PT Dual Port Server Adapter
.It
Intel PRO/1000 PT Quad Port Low Profile Server Adapter
.It
Intel PRO/1000 PT Quad Port Server Adapter
.It
Intel PRO/1000 PT Server Adapter
.It
Intel PRO/1000 T Server Adapter
.It
Intel PRO/1000 XT Low Profile Server Adapter
.It
Intel PRO/1000 XT Server Adapter
.El
.Pp
The
.Nm emx
driver supports Gigabit Ethernet adapters based on the Intel
82571, 82572, 82573, 82574, I217 and I218 controller chips.
.Sh TUNABLES
Tunables can be set at the
.Xr loader 8
prompt before booting the kernel or stored in
.Xr loader.conf 5 .
.Em Y
is the device unit number.
.Bl -tag -width "hw.em.int_throttle_ceil"
.It Va hw.em.int_throttle_ceil
Hardware interrupt throttling rate.
The default value is 6000Hz.
This tunable also applies to
.Nm emx .
.Nm emx
has a per device tunable
.Va hw.emxY.int_throttle_ceil ,
which serves the same purpose.
.It Va hw.em.rxd
Number of receive descriptors allocated by the driver.
The default value is 512.
The 82542 and 82543-based adapters can handle up to 256 descriptors,
while others can have up to 4096.
This tunable also applies to
.Nm emx .
.Nm emx
has a per device tunable
.Va hw.emxY.rxd ,
which serves the same purpose.
.It Va hw.em.txd
Number of transmit descriptors allocated by the driver.
The default value is 512.
The 82542 and 82543-based adapters can handle up to 256 descriptors,
while others can have up to 4096.
This tunable also applies to
.Nm emx .
.Nm emx
has a per device tunable
.Va hw.emxY.txd ,
which serves the same purpose.
.It Va hw.em.msi.enable Va hw.emY.msi.enable
By default, the driver will use MSI if it is supported.
This behavior can be turned off by setting these tunable to 0.
These tunables also applies to
.Nm emx .
.It Va hw.emY.msi.cpu
If MSI is used,
it specifies the MSI's target CPU.
This tunable also applies to
.Nm emx .
.It Va hw.emY.irq.unshared
If legacy interrupt is used,
by default,
the driver assumes the interrupt could be shared.
Setting this tunable to 1 allows the driver to
perform certain optimization based on the knowledge
that the interrupt is not shared.
These tunables also applies to
.Nm emx .
.It Va hw.emx.rxr Va hw.emxY.rxr
This tunable specifies the number of reception queues could be enabled.
Maximum allowed value for these tunables is 2.
Setting these tunables to 0 allows the driver to enable reception
queues based on the number of CPUs.
The default value is 0.
.It Va hw.emx.txr Va hw.emxY.txr
These tunables only take effect on 82571 and 82572.
This tunable specifies the number of transmission queues could be enabled.
Maximum allowed value for these tunables is 2.
Setting these tunables to 0 allows the driver to enable transmission
queues based on the number of CPUs.
The default value is 1.
.It Va hw.emxY.npoll.rxoff
This tunable specifies the leading target CPU for reception queues
.Xr polling 4
processing.
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.
.It Va hw.emxY.npoll.rxoff
This tunable specifies the leading target CPU for transmission queues
.Xr polling 4
processing.
The value specificed must be aligned to the number of transmission queues
enabled
and must be less than the power of 2 number of CPUs.
.El
.Sh MIB Variables
A number of per-interface variables are implemented in the
.Va hw.emx Ns Em Y
or
.Va hw.em Ns Em Y
branch of the
.Xr sysctl 3
MIB.
.Bl -tag -width "int_throttle_ceil"
.It Va rxd
Number of reception descriptors enabled (read-only).
Use the tunable
.Va hw.em.rxd
or
.Va hw.emY.rxd
to configure it.
.It Va txd
Number of transmission descriptors enabled (read-only).
Use the tunable
.Va hw.em.txd
or
.Va hw.emY.txd
to configure it.
.It Va int_throttle_ceil
See the tunable
.Va hw.em.int_throttle_ceil .
.It Va int_tx_nsegs
This value controls how many transmit descriptors should be consumed
by the hardware before the hardware generates a transmit interrupt.
The default value is 1/16 of the number of transmit descriptors.
If
.Xr polling 4
is not used on the hardware and
the major part of the transmitted data are bulk data,
this value could safely be set to 1/2 of the number of transmit descriptors.
.It Va tx_wreg_nsegs
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.
Default value is 8.
.It Va rx_ring_cnt
Number of reception queues enabled (read-only).
This sysctl only applies to
.Nm emx .
Use the tunable
.Va hw.emx.rxr
or
.Va hw.emxY.rxr
to configure it.
.It Va tx_ring_cnt
Number of transmission queues that can be enabled (read-only).
This sysctl only applies to
.Nm emx .
Use the tunable
.Va hw.emx.txr
or
.Va hw.emxY.txr
to configure it.
.It Va tx_ring_inuse
Number of transmission queues being used (read-only).
This sysctl only applies to
.Nm emx .
.It Va npoll_rxoff
See the tunable
.Va hw.emxY.npoll.rxoff .
The set value will take effect the next time
.Xr polling 4
is enabled on the device.
This sysctl only applies to
.Nm emx .
.It Va npoll_txoff
See the tunable
.Va hw.emxY.npoll.txoff .
The set value will take effect the next time
.Xr polling 4
is enabled on the device.
This sysctl only applies to
.Nm emx .
.El
.\".Sh SUPPORT
.\"For general information and support,
.\"go to the Intel support website at:
.\".Pa http://support.intel.com .
.\".Pp
.\"If an issue is identified with the released source code on the supported kernel
.\"with a supported adapter, email the specific information related to the
.\"issue to
.\".Aq Mt freebsdnic@mailbox.intel.com .
.Sh SEE ALSO
.Xr arp 4 ,
.Xr ifmedia 4 ,
.Xr netintro 4 ,
.Xr ng_ether 4 ,
.Xr polling 4 ,
.Xr vlan 4 ,
.Xr ifconfig 8
.Sh HISTORY
The
.Nm
device driver first appeared in
.Fx 4.4
and the
.Nm emx
driver first appeared in
.Dx 2.3 .
.Sh AUTHORS
.An -nosplit
The
.Nm
driver was written by
.An Intel Corporation Aq Mt freebsdnic@mailbox.intel.com .
.Pp
The
.Nm emx
driver was written by
.An Sepherosa Ziehau
(in parts based on
.Tn Intel Ap s ) .