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Software Developer’s Manual 209
Dual Port Characteristics
12.5.3 Multi-Function Advertisement
If one of the LAN devices is disabled, the Ethernet controller no longer is a multi-function device.
It normally reports a 01h in the PCI Configuration Header field Header Type, indicating multi-
function capability. However, if a LAN id disabled, it reports a 0h in this filed to signify single-
function capability.
12.5.4 Interrupt Use
When both LAN devices are enabled, the Ethernet controller uses both the INTA# and INTB# pins
for interrupt-reporting. The EEPROM Initialization Control Word 3 (bit 4) associated with each
LAN device controls which of these two pins is used for each LAN device. The specific interrupt
pin used is reported in the PCI Configuration Header
Interrupt Pin field associated with each LAN
device.
However, if either LAN device is disabled, then the INTA# be used for the remaining LAN device,
regardless of the EEPROM configuration. Under these circumstances, the
Interrupt Pin field of the
PCI Header always reports a value of 1h, indicating INTA# usage.
12.5.5 Power Reporting
When both LAN devices are enabled, the PCI Power Management Register Block has the
capability of reporting a Common Power value. The Common Power value is reflected in the data
field of the PCI Power Management registers. The value reported as Common Power is specified
via EEPROM, and is reflected in the data field each time the
Data_Select field has a value of 8h
(8h = Common Power Value Select).
When either LAN is disabled and the Ethernet controller appears as a single-function device, the
Common Power value, if selected, reports 0h (undefined value), as Common Power is undefined
for a single-function device.