Intel Intel Gigabit Ethernet Controllers, PCI-X manual Mpe, Lpe, Lbm, Rdmts

				Register Descriptions
	Field	Bit(s)	Initial	Description
			Value
				Multicast Promiscuous Enabled
				0b = Disabled.
	MPE	4	0b	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.
				Long Packet Reception Enable
				0b = Disabled.
				1b = Enabled.
	LPE	5	0b	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.
				Loopback mode.
				Controls the loopback mode of the Ethernet controller.
				00b = No loopback.
				01b = Undefined.
				10b = Undefined.
	LBM	7:6	0b	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.
				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
	RDMTS	9:8	0b	buffer is set by RDLEN. See Section 13.4.27 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
	Reserved	11:10	0b	Should be written with 0b to ensure future compatibility.
				Reads as 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
	MO	13:12	0b	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
	Reserved	14	0b	Should be written with 0 to ensure future compatibility
				Reads as 0
Software Developer’s Manual				297