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Software Developer’s Manual 145
Power Management
After receiving a wakeup packet, the Ethernet controller ignores any subsequent wakeup packets
until the driver clears all of the “Received” bits in the Wakeup Status Register (WUS). It also
ignores link change events until the driver clears the Link Status Changed (LNKC) bit in the
Wakeup Status Register (WUSR).
6.4.3 Wakeup Packets
The Ethernet controller supports various wakeup packets using two types of filters:
• Pre-defined Filters
• Flexible Filters
Each of these filters are enabled if the corresponding bit in the Wakeup Filter Control Register
(WUFC) is set to 1b.
6.4.3.1 Pre-Defined Filters
The following packets are supported by the Ethernet controller’s pre-defined filters:
• Directed Packet (including exact, multicast indexed, and broadcast)
• Magic Packet* (not applicable to the 82541ER)
• ARP/IPv4 Request Packet (ARP Request Packet for the 82544GC/EI)
• Directed IPv4 Packet (Directed IP Packet for the 82544GC/EI)
• Directed IPv6 Packet
1
Each of these filters are enabled if the corresponding bit in the Wakeup Filter Control Register
(WUFC) is set to 1b.
The following explanation of each filter includes a table listing which bytes at which offsets are
compared to determine if the packet passes the filter. Note that both VLAN
2
frames and LLC/Snap
can increase the given offsets if they are present (see Section 9.3 for details).
For the
82541PI/GI/EI and 82547GI/EI, various tables can also include a reference to a possible
VLAN Tag and LLC/SNAP Header. These Ethernet controllers detect VLAN and LLC/Snap
frames by checking the initial size/type field. They first check for a VLAN header by comparing
the size/type field to the value programmed in the VLAN EtherType register. If the field matches,
the Ethernet controllers consider the frame a VLAN frame. They then check the VLAN ID against
the values programmed in the VLAN Filter Table Array. If the ID matches the packet, processing
continues. If the ID doesn’t match, or the CTRL.VME bit is 0b, and the VLAN Tag is listed as
compare in the table, the packet is not considered a wakeup packet.
After processing a possible VLAN Tag, the
82541PI/GI/EI and 82547GI/EI Ethernet controllers
check for an LLC/SNAP Header. If the size/type field is less than or equal to 1500 bytes, they
check the following 6 bytes for the pattern of AAAA03000000h. If the pattern matches, then the
packet processing continues. If the pattern doesn’t match, and the LLC/SNAP Header is listed as
compare or check in the table, the packet is not considered a wakeup packet.
6.4.3.1.1 Directed Exact Packet
1. Not applicable to the 82544GC/EI.
2. Not applicable to the 82541ER.