Intel PCI User Manual

297

MPE

4

0b

Multicast Promiscuous Enabled
0b = Disabled.
1b = Enabled.
When set, passes without filtering out all received multicast packets. 
Otherwise, the Ethernet controller accepts or rejects a multicast 
packet based on its 4096-bit vector multicast filtering table.

LPE

5

0b

Long Packet Reception Enable
0b = Disabled.
1b = Enabled.
LPE controls whether long packet reception is permitted. When LPE 
is cleared, the Ethernet controller discards packets longer than 
1522 bytes. When LPE is set, the Ethernet controller discards 
packets that are longer than 16384 bytes.
For the 82541xx and 82547GI/EI, packets larger than 2 KB require 
full duplex operation.

LBM

7:6

0b

Loopback mode.
Controls the loopback mode of the Ethernet controller.
00b = No loopback.
01b = Undefined.
10b = Undefined.
11b = PHY or external SerDes loopback.
All loopback modes are only allowed when the Ethernet controller is 
configured for full-duplex operation. Receive data from transmit 
data looped back internally to the SerDes or internal PHY. In TBI 
mode (82544GC/EI), the EWRAP signal is asserted.
Note: The 82540EP/EM, 82541xx, and 82547GI/EI do not support 
SerDes functionality.

RDMTS

9:8

0b

Receive Descriptor Minimum Threshold Size
The corresponding interrupt ICR.RXDMT0 is set each time the 
fractional number of free descriptors becomes equal to RDMTS. 
The following table lists which fractional values correspond to 
RDMTS values. The size of the total receiver circular descriptor 
buffer is set by RDLEN. See 

 for details regarding 

RDLEN.
00b = Free Buffer threshold is set to 1/2 of RDLEN.
01b = Free Buffer threshold is set to 1/4 of RDLEN.
10b = Free Buffer threshold is set to 1/8 of RDLEN.
11b = Reserved.

Reserved

11:10

0b

Reserved
Should be written with 0b to ensure future compatibility.
Reads as 0b.

MO

13:12

0b

Multicast Offset
The Ethernet controller is capable of filtering multicast packets 
based on 4096-bit vector multicast filtering table. The MO 
determines which bits of the incoming multicast address are used in 
looking up the 4096-bit vector.
00b = bits [47:36] of received destination multicast address.
01b = bits [46:35] of received destination multicast address.
10b = bits [45:34] of received destination multicast address.
11b = bits [43:32] of received destination multicast address.

Reserved 14

0b

Reserved
Should be written with 0 to ensure future compatibility
Reads as 0