JME(4)                 FreeBSD Kernel Interfaces Manual                 JME(4)

NAME
     jme - JMicron Gigabit/Fast Ethernet driver

SYNOPSIS
     To compile this driver into the kernel, place the following lines in your
     kernel configuration file:

           device miibus
           device jme

     Alternatively, to load the driver as a module at boot time, place the
     following line in loader.conf(5):

           if_jme_load="YES"

DESCRIPTION
     The jme device driver provides support for JMicron JMC25x PCI Express
     Gigabit Ethernet controllers and JMicron JMC26x PCI Express Fast Ethernet
     controllers.

     All LOMs supported by the jme driver have TCP/UDP/IP checksum offload for
     both transmit and receive, TCP segmentation offload (TSO), hardware VLAN
     tag stripping/insertion features, Wake On Lan (WOL) and an interrupt
     coalescing/moderation mechanism as well as a 64-bit multicast hash
     filter.

     The JMC25x 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 ifconfig(8) utility configures the adapter to receive
     and transmit Jumbo Frames.

     The jme driver supports the following media types:

     autoselect       Enable autoselection of the media type and options.  The
                      user can manually override the autoselected mode by
                      adding media options to rc.conf(5).

     10baseT/UTP      Set 10Mbps operation.

     100baseTX        Set 100Mbps (Fast Ethernet) operation.

     1000baseTX       Set 1000baseTX operation over twisted pair.

     The jme driver supports the following media options:

     full-duplex      Force full duplex operation.

     half-duplex      Force half duplex operation.

     For more information on configuring this device, see ifconfig(8).

HARDWARE
     The jme device driver provides support for the following Ethernet
     controllers:

     •   JMicron JMC250 PCI Express Gigabit Ethernet controller
     •   JMicron JMC251 PCI Express Gigabit Ethernet with Card Read Host
         controller
     •   JMicron JMC260 PCI Express Fast Ethernet controller
     •   JMicron JMC261 PCI Express Gigabit Ethernet with Card Read Host
         controller

LOADER TUNABLES
     Tunables can be set at the loader(8) prompt before booting the kernel or
     stored in loader.conf(5).

     hw.jme.msi_disable
             This tunable disables MSI support on the Ethernet hardware.  The
             default value is 0.

     hw.jme.msix_disable
             This tunable disables MSI-X support on the Ethernet hardware.
             The default value is 0.

SYSCTL VARIABLES
     The following variables are available as both sysctl(8) variables and
     loader(8) tunables:

     dev.jme.%d.tx_coal_to
             This variable sets the maximum amount of time to delay before
             sending a Tx completion interrupt, in microseconds.  The accepted
             range is 1 to 65535; the default is 100 (100us).

     dev.jme.%d.tx_coal_pkt
             This variable sets the maximum number of outgoing packets which
             may be coalesced together into a single Tx completion interrupt.
             The accepted range is 1 to 255; the default is 8.

     dev.jme.%d.rx_coal_to
             This variable sets the maximum amount of time to wait for
             additional packets to arrive (for possible packet coalescing)
             before firing an Rx completion interrupt, in microseconds.  The
             accepted range is 1 to 65535; the default is 100 (100us).

     dev.jme.%d.rx_coal_pkt
             This variable sets the maximum number of incoming packets which
             may be coalesced into a single Rx completion interrupt.  The
             accepted range is 1 to 255; the default is 2.

     dev.jme.%d.process_limit
             This variable sets the maximum number of events that will be
             processed in a single batch before the handler is requeued into a
             taskqueue.  The accepted range is 10 to 255; the default value is
             128 events.  The interface does not need to be brought down and
             up again before a change takes effect.

SEE ALSO
     altq(4), arp(4), miibus(4), netintro(4), ng_ether(4), vlan(4),
     ifconfig(8)

HISTORY
     The jme driver was written by Pyun YongHyeon <yongari@FreeBSD.org>.  It
     first appeared in FreeBSD 7.1.

CAVEATS
     The jme driver tries to avoid unnecessary station address reprogramming
     for controllers that use eFuse to store station address.  The number of
     times that eFuse can be safely reprogrammed is 16 at most.  In addition,
     there is no way to restore the factory default station address once the
     station address has been reprogrammed via eFuse.  It is highly
     recommended not to reprogram the station address and it is the
     responsibility of the administrator to store the original station address
     in a safe place when station address is changed.

     There are two known 1000baseT link establishment issues with JMC25x.  If
     the full mask revision number of JMC25x controller is less than or equal
     to 4 and the link partner enabled the IEEE 802.3az Energy Efficient
     Ethernet feature,  the controller will not be able to establish a
     1000baseT link.  Also, if the length of the cable is longer than 120
     meters, the controller can not establish a 1000baseT link.  The known
     workaround for these issues is to force manual link configuration with
     100baseTX instead of relying on auto-negotiation.  The full mask revision
     number of controller can be checked with the verbose kernel boot option.
     Use the lower nibble of the chip revision number to get the full mask
     revision of the controller.

FreeBSD 13.1-RELEASE-p6          March 4, 2012         FreeBSD 13.1-RELEASE-p6