Chelsio Advanced Configuration

  • I am trying to load the t4_tom module, as stated in the userguide, and properly enable TOE for this Chelsio t422-CR adapter, is this possible?

    The Chelsio-UnifiedWire-FreeBSD-UserGuide.pdf has steps on how to do this however I'm receiving some errors.

    Enable TCP offload on a T4 interface using ifconfig. An error usually indicates that t4_tom is not
    [root@host~]# ifconfig cxgbeX toe
    If successful, TOE4 and TOE6 will be displayed on the list of the enabled options.

    "ifconfig cxgbe0 toe" unfortunately results in the following error:
    ifconfig: toe: Resource temporarily unavailable

    "ifconfig cxgbe0" does NOT show TOE3 and TOE6 present in the listed options

    Sub-Section 3.4 "Connection Offload Policies (COP)" step 1 explains how to load t4_tom:

    If not completed already, load NIC and TOE drivers:
    [root@host~]# kldload if_cxgbe
    [root@host~]# kldload t4_tom

    Which also results in the following errors:
    kldload: can't load if_cxgbe: No such file or directory
    kldload: can't load t4_tom: No such file or directory

    How can I load t4_tom and enable some of the advanced features of my Chelsio card?
    Specifically I'm trying to ensure the full TCP/UDP offload engine is enabled.

    Thank you very much for your time and have a wonderful day!

  • Netgate Administrator

    cxgbe is already in kernel. t4_tom is not included, you would need to move it across from a FreeBSD source.

    However TCP offload is unlikely to make much difference on a firewall which is mostly only forwarding packets. Even if you did get it working.


  • Thank you for the reply. Our use case is latency sensitive and any improvement, no matter how small, is time well spent. I do however understand that PfSense is mostly only forwarding packets so at the very least it would be interesting to benchmark the results after enabling these features.
    These cards are quite expensive and even sold on the netgate store, that being said they are essentially being endorsed by the company as a preferred adapter. I see no reason why all the available features should not be readily accessible within PfSense by default? Is this a feature request that can be made somewhere?

  • Netgate Administrator

    Sure you can open a feature request here:


  • For anyone interested, a feature request has been added to the bug tracker here:

    More information on offloads from

    " When a TOE capable interface is the outbound path to a destination to which a
    new connection is being established, the connection should be offloaded

    It would stand to reason that if your system was setup to use one or more Chelsio adapters, either exclusively or as an adapter that saw heavy traffic (WAN facing adapter), then every packet PfSense routed/forwarded over one such adapter would benefit from offloading.