Intel PCI User Manual

169

CTRL.FRCSPD = CTRL.FRCDPLX = CTRL.SLU = 1b

For the 82546GB/EB and 82545GM/EM, the internal LOS signal allows for indication of physical 

link status to the Ethernet controller’s MAC.

For the 82544GC/EI, the LOS input is provided to allow for indication of physical link status to 
the Ethernet controller. When the 82544GC/EI is configured in TBI mode, the input is typically 

connected to the loss-of-signal connection from the optics while in internal PHY mode.

If the LSC (Link Status Change) interrupt is enabled, the hardware posts an interrupt to be serviced 

by the software driver when the link goes up or down. See 

 for more details.

When asserted, LOS indicates there is no activity on the fiber due to either an unplugged cable or a 
defective optical device. An assertion on LOS implies the link is not available and the hardware is 

disabled. This is true whether the link is forced by the Set Link Up bit (CTRL.SLU) or if the 

Ethernet controller is configured to perform Auto-Negotiation. When Auto-Negotiation is enabled, 
the Ethernet controller is forced to restart Auto-Negotiation but does not complete the negotiation 

process until the LOS is deasserted.

While in internal PHY mode, an internal signal provides status of the physical link as indicated by 

the PHY. Indication that the link is not up disables MAC operation. Upon determination of a valid 

link, the assertion of the internal link signal asserts the LSC interrupt (if enabled) to indicate to the 
software driver to check the link status.

CTRL.FD

Set by software.

CTRL.SLU

Set by software, and assumed PHY is also forced to assert link.

CTRL.RFCE

Set by software for the desired mode of operation.

CTRL.TFCE

Set by software for the desired mode of operation.

CTRL.SPEED 

Set by software.

STATUS.FD

Reflects the value of CTRL.FD.

STATUS.LU

Reflects CTRL.SLU set and internal link status.

STATUS.SPEED

Reflects CTRL.SPEED.

1.

TBI mode for the 82544GC/EI.