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.

 

 

 

 

298

Software Developer’s Manual

Page 312
Image 312
Intel PCI-X, Intel Gigabit Ethernet Controllers manual Bam, Bsize, Vfe, Cfien, Dpf