The procedure that follows describes how to set forced mode (not capable of auto-negotiation).
Select one of the following capabilities: adv_100fdx_cap, adv_100hdx_cap, adv_10fdx_cap, or adv_10hdx_cap, and set its value to 1.
If you select more than one of the local transceiver capabilities, the driver selects the one that is highest in the priority order.
Set the local transceiver capabilities advertised by the hardware to forced mode = 0, which is not capable of auto-negotiation: adv_autoneg_cap 0
Use the ndd utility as described in "Using the ndd Utility in Interactive Mode" in this chapter.