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144 Software Developer’s Manual
Power Management
The Ethernet controller generates a wakeup event after receiving any packet whose destination
address matches one of the 16 valid programmed Receive Addresses if the
Directed Exact Wakeup
Enable
bit is set in the Wakeup Filter Control Register (WUFC.EX).
6.4.3.1.2 Directed Multicast Packet
For multicast packets, the upper bits of the incoming packet’s destination address indexes a bit
vector (
Multicast Table Array) that indicates whether to accept the packet. If the Directed Multicast
Wakeup Enable
bit set in the Wakeup Filter Control Register (WUFC.MC) and the indexed bit in
the vector is one then the Ethernet controller generates a wakeup event. The exact bits used in the
comparison are programmed by software in the Multicast Offset field of the Receive Control
Register (RCTL.MO).
6.4.3.1.3 Broadcast
If the Broadcast Wakeup Enable bit in the Wakeup Filter Control Register (WUFC.BC) is set, the
Ethernet controller generates a wakeup event when it receives a broadcast packet.
6.4.3.1.4 Magic Packet*
1
Magic Packet* technology is defined at: http://www.amd.com/products/npd/overview/20212.html.
The Ethernet controller expects the destination address to:
1. Be the broadcast address (FF.FF.FF.FF.FF.FF)
2. Match the value in Receive Address Register 0 (RAH0, RAL0). This is initially loaded from
the EEPROM but can be changed by the software driver.
3. Match any other address filtering enabled by the software driver.
The Ethernet controller searches for the contents of Receive Address Register 0 (RAH0, RAL0) as
the embedded IEEE address. It considers any non FF byte after a series of at least 6 FFs to be the
start of the address for comparison purposes (for example, it catches the case of 7 FFs followed by
the address). As soon as one of the first 96 bytes after a string of FFs doesn’t match, it continues to
search for anther set of at least 6 FFs followed by the 16 copies of the IEEE address later in the
packet. Note that this definition precludes the first byte of the destination address from being FF.
Offset
# of
bytes
Field Value Action Comment
0 6 Destination Address Compare
Match any pre-
programmed address
Offset
# of
Bytes
Field Value Action Comment
0 6 Destination Address Compare See Section 6.4.3.1.2.
Offset
# of
bytes
Field Value Action Comment
0 6 Destination Address FF*6 Compare
1. Not applicable to the 82541ER.