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
    Maximum amount of time to delay for Tx completion interrupt in units of 1us. The accepted range is 1 to 65535, the default is 100 (100us).

dev.jme.%d.tx_coal_pkt
    Maximum number of packets to fire Tx completion interrupt. The accepted range is 1 to 255, the default is 8.

dev.jme.%d.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 100 (100us).

dev.jme.%d.rx_coal_pkt
    Maximum number of packets to fire Rx completion interrupt. The accepted range is 1 to 255, the default is 2.

dev.jme.%d.process_limit
    Maximum amount of Rx events to be processed in the event loop before rescheduling 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 factory default station address once station address is reprogrammed via eFuse. It is highly recommended not to reprogram station address and it is responsibility of administrator to store original station address into a safe place when station address should be 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 link partner enabled IEEE 802.3az Energy Efficient Ethernet feature, the controller would not be able to establish a 1000baseT link. Also if the length of cable is longer than 120 meters, controller can not establish a 1000baseT link. The known workaround for the issue is to force manual link configuration with 100baseTX instead of relying on auto-negotiation. The full mask revision number of controller could be checked with verbose kernel boot option. Use lower nibble of chip revision number to get full mask revision of the controller.