Intel PCI-X, Intel Gigabit Ethernet Controllers manual Bam, Bsize, Vfe, Cfien, Dpf

Register Descriptions

Field	Bit(s)	Initial	Description
		Value
			Broadcast Accept Mode.
			0 = ignore broadcast; 1 = accept broadcast packets.
BAM	15	0b	When set, passes and does not filter out all received broadcast
			packets. Otherwise, the Ethernet controller accepts, or rejects a
			broadcast packet only if it matches through perfect or imperfect
			filters.
			Receive Buffer Size
			Controls the size of the receive buffers, allowing the software to
			trade off between system performance and storage space. Small
			buffers maximize memory efficiency at the cost of multiple
			descriptors for bigger packets.
			RCTL.BSEX = 0b:
			00b = 2048 Bytes.
BSIZE	17:16	0b	01b = 1024 Bytes.
			10b = 512 Bytes.
			1b1 = 256 Bytes.
			RCTL.BSEX = 1b:
			00b = Reserved; software should not program this value.
			01b = 16384 Bytes.
			10b = 8192 Bytes.
			11b = 4096 Bytes.
			VLAN Filter Enable1
			0b = Disabled (filter table does not decide packet acceptance).
			1b = Enabled (filter table decides packet acceptance for 802.1Q
VFE	18	0b	packets).
			Three bits control the VLAN filter table. RCTL.VFE determines
			whether the VLAN filter table participates in the packet acceptance
			criteria. RCTL.CFIEN and RCTL.CFI are used to decide whether
			the CFI bit found in the 802.1Q packet’s tag should be used as part
			of the acceptance criteria.
			Canonical Form Indicator Enable
			0b = Disabled (CFI bit found in received 802.1Q packet’s tag is not
CFIEN	19	0b	compared to decide packet acceptance).
			1b = Enabled (CFI bit found in received 802.1Q packet’s tag must
			match RCTL.CFI to accept 802.1Q type packet.
CFI	20	0b	Canonical Form Indicator bit value
			If RCTL.CFIEN is set, then 802.1Q packets with CFI equal to this
			field is accepted; otherwise, the 802.1Q packet is discarded.
			Reserved
Reserved	21	0b	Should be written with 0b to ensure future compatibility.
			Reads as 0b.
			Discard Pause Frames
			0 = incoming pause frames subject to filter comparison.
			1 = incoming pause frames are filtered out even if they match filter
DPF	22	0b	registers.
			DPF controls the DMA function of flow control PAUSE packets
			addressed to the station address (RAH/L[0]). If a packet is a valid
			flow control packet and is addressed to the station’s address, it is
			not transferred to host memory if RCTL.DPF = 1b. However, it is
			transferred when DPF is set to 0b.

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