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Software Developer’s Manual 147
Power Management
A Magic Packet’s destination address must match the address filtering enabled in the configuration
registers with the exception that broadcast packets are considered to match even if the
Broadcast
Accept
bit of the Receive Control Register (RCTL.BAM) is 0b. If APM Wakeup is enabled in the
EEPROM, Ethernet controller starts up with the Receive Address Register 0 (RAH0, RAL0)
loaded from the EEPROM. This is enables it to accept packets with the matching IEEE address
before the driver comes up.
Note: Accepting broadcast magic packets for wakeup purposes when the Broadcast Accept bit of the
Receive Control Register (RCTL.BAM) is 0b is a change from the
82544GC/EI Ethernet
controller, which initialized RCTL.BAM to 1b if APM was enabled in the EEPROM, but then
required that bit to be 1b to accept broadcast Magic Packets, unless broadcast packets passed
another perfect or multicast filter.
Offset
# of
bytes
Field Value Action Comment
0 6 Destination Address Compare MAC Header –
processed by main
address filter
6 6 Source Address Skip
12
a
8 Possible LLC/SNAP Header Skip
12
a
4 Possible VLAN Tag Skip
12
a
4 Type Skip
any 6 Synchronizing Stream FF*6+ Compare
any+6 96 16 copies of Node Address A*16 Compare
Compared to Receive
Address Register 0
(RAH0, RAL0)
a. Not applicable to the 82541PI/GI/EI and 82547GI/EI.