CAS(4) FreeBSD Kernel Interfaces Manual CAS(4)


casSun Cassini/Cassini+ and National Semiconductor DP83065 Saturn Gigabit Ethernet driver


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

device miibus
device cas

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



The cas driver provides support for the Sun Cassini/Cassini+ and National Semiconductor DP83065 Saturn Gigabit Ethernet controllers found on-board in Sun UltraSPARC machines and as add-on cards.

All controllers supported by the cas driver have TCP/UDP checksum offload capability for both receive and transmit, support for the reception and transmission of extended frames for vlan(4) and an interrupt coalescing/moderation mechanism as well as a 512-bit multicast hash filter.

The cas driver also supports Jumbo Frames (up to 9022 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 chips supported by the cas driver are:

  • National Semiconductor DP83065 Saturn Gigabit Ethernet
  • Sun Cassini Gigabit Ethernet
  • Sun Cassini+ Gigabit Ethernet

The following add-on cards are known to work with the cas driver at this time:

  • Sun GigaSwift Ethernet 1.0 MMF (Cassini Kuheen) (part no. 501-5524)
  • Sun GigaSwift Ethernet 1.0 UTP (Cassini) (part no. 501-5902)
  • Sun GigaSwift Ethernet UTP (GCS) (part no. 501-6719)
  • Sun Quad GigaSwift Ethernet UTP (QGE) (part no. 501-6522)
  • Sun Quad GigaSwift Ethernet PCI-X (QGE-X) (part no. 501-6738)


On sparc64 the cas driver respects the local-mac-address? system configuration variable which can be set in the Open Firmware boot monitor using the setenv command or by eeprom(8). If set to “ false” (the default), the cas driver will use the system's default MAC address for all of its devices. If set to “ true”, the unique MAC address of each interface is used if present rather than the system's default MAC address.

Supported interfaces having their own MAC address include on-board versions on boards equipped with more than one Ethernet interface and all add-on cards.


The cas device driver appeared in FreeBSD 8.0 and FreeBSD 7.3. It is named after the cas driver which first appeared in OpenBSD 4.1 and supports the same set of controllers but is otherwise unrelated.


The cas driver was written by Marius Strobl <marius@FreeBSD.org> based on the gem(4) driver.
March 24, 2012 FreeBSD