| Main index | Section 4 | Options |
Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):
if_em_load="YES"
The em driver also provides support for PCI Express Gigabit Ethernet adapters based on the Intel 82575, 82576, 82580, i21x and i35x.
The driver supports Transmit/Receive checksum offload and Jumbo Frames on all but 82542-based adapters.
Furthermore it supports TCP segmentation offload (TSO) on all adapters but those based on the 82543, 82544 and 82547 controller chips. The identification LEDs of the adapters supported by the em driver can be controlled via the led(4) API for localization purposes. For further hardware information, see the README included with the driver.
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 FreeBSD .
Support for Jumbo Frames is provided 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 maximum MTU size for Jumbo Frames is 16114.
This driver supports hardware assisted VLANs. The em driver supports the following media types:
| autoselect | Enables auto-negotiation for speed and duplex. |
| 10baseT/UTP | |
| Sets 10Mbps operation. Use the mediaopt option to select full-duplex mode. | |
| 100baseTX | Sets 100Mbps operation. Use the mediaopt option to select full-duplex mode. |
| 1000baseSX | Sets 1000Mbps operation. Only full-duplex mode is supported at this speed. |
| 1000baseTX | Sets 1000Mbps operation. Only full-duplex mode is supported at this speed. |
The em driver supports the following media options:
| full-duplex | |
| Forces full-duplex operation | |
| half-duplex | |
| Forces half-duplex operation. | |
Only use mediaopt to set the driver to full-duplex. If mediaopt is not specified, the driver defaults to half-duplex.
For more information on configuring this device, see ifconfig(8).
| hw.em.disable_crc_stripping | |
| Disable or enable hardware stripping of CRC field. This is mostly useful on BMC/IPMI shared interfaces where stripping the CRC causes remote access over IPMI to fail. Default 0 (enabled). | |
| hw.em.eee_setting | |
| Disable or enable Energy Efficient Ethernet. Default 1 (disabled). | |
| hw.em.msix | |
| Enable or disable MSI-X style interrupts. Default 1 (enabled). | |
| hw.em.smart_pwr_down | |
| Enable or disable smart power down features on newer adapters. Default 0 (disabled). | |
| hw.em.sbp | |
| Show bad packets when in promiscuous mode. Default 0 (off). | |
| hw.em.rxd | |
| Number of receive descriptors allocated by the driver. The default value is 1024 for adapters newer than 82547, and 256 for older ones. The 82542 and 82543-based adapters can handle up to 256 descriptors, while others can have up to 4096. | |
| hw.em.txd | |
| Number of transmit descriptors allocated by the driver. The default value is 1024 for adapters newer than 82547, and 256 for older ones. The 82542 and 82543-based adapters can handle up to 256 descriptors, while others can have up to 4096. | |
| hw.em.rx_int_delay | |
| This value delays the generation of receive interrupts in units of 1.024 microseconds. The default value is 0, since adapters may hang with this feature being enabled. | |
| hw.em.rx_abs_int_delay | |
| If hw.em.rx_int_delay is non-zero, this tunable limits the maximum delay in which a receive interrupt is generated. | |
| hw.em.tx_int_delay | |
| This value delays the generation of transmit interrupts in units of 1.024 microseconds. The default value is 64. | |
| hw.em.tx_abs_int_delay | |
| If hw.em.tx_int_delay is non-zero, this tunable limits the maximum delay in which a transmit interrupt is generated. | |
| /dev/led/em* | |
| identification LED device nodes | |
echo f2 > /dev/led/em0
Turn the identification LED of em0 off again:
echo 0 > /dev/led/em0
| em%d: Unable to allocate bus resource: memory | A fatal initialization error has occurred. |
| em%d: Unable to allocate bus resource: interrupt | A fatal initialization error has occurred. |
| em%d: watchdog timeout -- resetting | The device has stopped responding to the network, or there is a problem with the network connection (cable). |
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 <Mt freebsd@intel.com>.
| EM (4) | January 30, 2019 |
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