Intel PCI-X, Intel Gigabit Ethernet Controllers manual Pmcf, Bsex, Secrc

			Register Descriptions
Field	Bit(s)	Initial	Description
		Value
			Pass MAC Control Frames
			0b = Do not (specially) pass MAC control frames.
			1b = Pass any MAC control frame (type field value of 8808h) that
			does not contain the pause opcode of 0001h.
PMCF	23	0b	PMCF controls the DMA function of MAC control frames (other than
			flow control). A MAC control frame in this context must be
			addressed to either the MAC control frame multicast address or the
			station address, match the type field and NOT match the PAUSE
			opcode of 0001h. If PMCF = 1b then frames meeting this criteria are
			transferred to host memory. Otherwise, they are filtered out.
			Reserved
Reserved	24	0b	Should be written with 0b to ensure future compatibility.
			Reads as 0b.
BSEX	25	0b	Buffer Size Extension
			When set to one, the original BSIZE values are multiplied by 16.
			Refer to the RCTL.BSIZE bit description.
			Strip Ethernet CRC from incoming packet
			0b = Do not strip CRC field.
SECRC	26	0b	1b = Strip CRC field.
			Controls whether the hardware strips the Ethernet CRC from the
			received packet. This stripping occurs prior to any checksum
			calculations. The stripped CRC is not transferred to host memory
			and is not included in the length reported in the descriptor.
			Reserved
Reserved	31:27	0b	Should be written with 0b to ensure future compatibility.
			Reads as 0b.

1.Not applicable to the 82541ER.

Software Developer’s Manual 299