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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.