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Intel
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82575EB Gigabit Ethernet Controller — Wake-Up Packets
Intel
®
82575EB Gigabit Ethernet Controller 324632-003
Software Developer’s Manual and EEPROM Guide Revision: 2.1
234 January 2011
For multicast packets, the upper bits of the destination address in the incoming packet index a bit
vector. This is the Multicast Table Array that indicates whether to accept the packet. If the Directed
Multicast Wake Up Enable bit is set in the Wake Up Filter Control Register (WUFC.MC) and the indexed
bit in the vector is 1b, then the 82575 generates a wake-up event. The exact bits used in the
comparison are programmed by software in the Multicast Offset field of the Receive Control Register
(RCTL.MO).
7.5.3.1.3 Broadcast
If the Broadcast Wake Up Enable bit in the Wake Up Filter Control Register (WUFC.BC) is set, the 82575
generates a wake-up event when it receives a broadcast packet.
7.5.3.1.4 Magic Packet*
The definition for a Magic Packet* can be located at:
http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/20213.pdf.
The 82575 expects the destination address to either:
• Be the broadcast address (FF.FF.FF.FF.FF.FF).
• Match the value in the Receive Address Register 0 (RAH0, RAL0). This is initially loaded from the
EEPROM but might be changed by the software device driver.
• Match any other address filtering enabled by the software device driver.
The 82575 looks for the contents of Receive Address Register 0 (RAH0, RAL0) as the embedded IEEE
address. It will consider any non-FFh byte after a series of at least 6 FFs to be the start of the IEEE
address for comparison purposes. For example, it catches the case of 7 FFs followed by the IEEE
address. As soon as one of the first 96 bytes after a string of FFs does not 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. It
should be noted that this definition precludes the first byte of the destination address from equaling FF.
A Magic Packet destination address must match the address filtering enabled in the configuration
registers with the exception that broadcast packets will be considered to match even if the Broadcast
Accept bit of the Receive Control Register (RCTL.BAM) is 0b. If APM Wake Up is enabled in the EEPROM,
the 82575 starts with the Receive Address Register 0 (RAH0, RAL0) loaded from the EEPROM. This
allows the 82575 to accept packets with the matching IEEE address before the driver comes up.
Offset
Number of
Bytes
Field Value Action Comment
0 6 Destination Address Compare See above paragraph.
Offset
Number of
Bytes
Field Value Action Comment
0 6 Destination Address ff*6 Compare
Offset
Number of
Bytes
Field Value Action Comment