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Software Developer’s Manual 149

Power Management

6.4.3.3 Flexible Filter

The Ethernet controller supports a total of four flexible filters. Each filter is configured to

recognize any arbitrary pattern within the first 128 bytes of the packet. To configure the flexible

filter, the software driver must mask values into the Flexible Filter Mask Table (FFMT), the

required values into the Flexible Filter Value Table (FFVT), and the minimum packet length into

the Flexible Filter Length Table (FFLT). These contain separate values for each filter. The software

driver must also enable the filter in the Wakeup Filter Control Register (WUFC) as well as the

overall wakeup functionality by setting

PME_En in the Power Management Control Status

Once enabled, the flexible filters scan incoming packets for a match. If the filter encounters any

byte in the packet where the mask bit is 1b and the byte doesn’t match the byte programmed in the

Flexible Filter Value Table (FFVT), then the filter failed that packet. If the filter reaches the

required length without failing the packet, it passes the packet and generates a wakeup event. It

ignores any mask bits set to 1b beyond the required length. (the wakeup packet is stored, see

Section 6.4.3.5).

For the

82541xx and 82547GI/EI, the flexible filter does not have any way to automatically skip

VLAN or LLC/SNAP headers. If such headers are included, the offsets of the subsequent fields

must be adjusted accordingly.

Note: This following flexible packet filters are listed for reference only.

6.4.3.3.1 IPX Diagnostic Responder Request Packet Example

1. 82541xx and 82547GI/EI only.

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 S = (0/4) Possible VLAN Tag

Compare or

Skip

12 + S D = (0/8) Possible LLC/SNAP Header

Compare or

Skip

12 + D + S 2 Type 8137h Compare IPX

14 + D + S 16 Some IPX Stuff - Ignore

30 + D + S 2 IPX Diagnostic Socket 0456h Compare