WG82574L S LBA8 Intel, WG82574L S LBA8 Datasheet - Page 152

• Manufacturer Part Number: WG82574L S LBA8
• Manufacturer: Intel

Specifications of WG82574L S LBA8

• Operating Supply Voltage (typ): 3.3V
• Operating Temp Range: 0C to 85C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 64
• Lead Free Status / RoHS Status: Compliant

7.2.10
7.2.10.1
Figure 31.
7.2.10.1.1
152
15
Transmit Descriptor Formats
The original descriptor is referred to as the legacy descriptor and is described in
section
descriptors. One of the new descriptor types is quite similar to the legacy descriptor in
that it points to a block of packet data. This descriptor type is called the extended data
descriptor. The other new descriptor type is fundamentally different as it does not point
to packet data. This descriptor type is called the context descriptor. It only contains
control information, which is loaded into registers of the 82574, and affects the
processing of future packets. The following paragraphs describe the three descriptor
formats.
The new descriptor types are specified by setting the TDESC.DEXT bit to 1b. If this bit
is set, the TDESC.DTYP field is examined to determine the descriptor type (extended
data or context).
shows the data descriptor generic layout.
Legacy Transmit Descriptor Format
Legacy Transmit Descriptor Format
The legacy Tx descriptor is defined by setting the DEXT bit in the command field to 0b.
The legacy Tx descriptor format is shown in
Buffer Address
The buffer address (TDESC.Buffer Address) specifies the location (address) in main
memory of the data to be fetched.
PRI
13 12 11
CFI
VLAN
7.2.10.1. The two new descriptor types are collectively referred to as extended
VLAN
0
0
8
8
Figure 32
63
CSS
Checksum
Start
VLAN
0
ExtCMD
3
48
shows the context descriptor generic layout.
47
1
CSS
TS
0
Rsv
40
3
39
Buffer Address [63:0]
ExtCMD
Res
2
36
Status
35
Res
STA
1
32
DD
31
CMD
0
Figure
IDE VLE DEXT RSV RS
7
24
23
CSO
6
31.
82574 GbE Controller—Inline Functions
5
16
Command
15
4
Length
0
3
IC
2
IFCS EOP
1
Checksum
Offset
0
Figure 34
8
CSO
0
Length
15
LENGTH