JME(4) | Device Drivers Manual | JME(4)

# NAME

`jme` — JMicron Technologies JMC250 Gigabit Ethernet and JMC260 Fast Ethernet controller driver

# SYNOPSIS

`jme* at pci? dev ? function ?`

Configuration of PHYs is necessary. See mii(4).

# DESCRIPTION

The `jme` device driver supports network adapters based on the JMicron Technologies JMC250 Gigabit Ethernet and JMC260 Fast Ethernet chips. The following features are supported:

    IPv4 transmit/receive IP/TCP/UDP checksum offload
    IPv6 transmit TCP/UDP checksum offload
    IPv4 and IPv6 TCP segmentation offload
    VLAN tag insertion/removal
    Interrupt coalescing
    10/100/1000Mbps operation in full-duplex mode
    10/100Mbps operation in half-duplex mode
    Jumbo frames (up to 9022 bytes)

Due to hardware limitation checksums and TCP segmentation offload can't be enabled if the configured MTU is larger than 4000 bytes.

Interrupt coalescing can be controlled on a per-adapter basis through the following sysctls:

`hw.jme.jme<x>.int_rxtos`
  jme receive interrupt moderation timer, in microseconds (defaults to 100)
`hw.jme.jme<x>.int_rxct`
  jme receive interrupt moderation packet counter (defaults to 128)
`hw.jme.jme<x>.int_txto`
  jme transmit interrupt moderation timer, in microseconds (defaults to 100)
`hw.jme.jme<x>.int_txct`
  jme transmit interrupt moderation packet counter (defaults to 128)

# SEE ALSO

ifmedia(4), jmphy(4), mii(4), netintro(4), pci(4), ifconfig(8)

# HISTORY

The `jme` device driver first appeared in NetBSD 5.0.

# BUGS

Hardware bugs prevent support of IPv6 receive TCP/UDP checksum offload in the JMC250 rev A2, and is disabled in the driver. This should be revisited when a newer hardware revision is available.

October 30, 2019 | NetBSD 10.99