82583V Datasheet, PDF (139/374 Pages) Intel Corporation – Intel® 82583V GbE Controller

Inline Functions—82583V GbE Controller
7.2.4.3
Determining Completed Frames as Done
Software can determine if a packet has been sent by the following method:
• Setting the RS bit in the transmit descriptor command field and checking the DD bit
of the relevant descriptors in host memory.
The process of checking for completed descriptors consists of the following:
• The software device driver scans the host memory for the value of the DD status
bit. When the DD bit =1b, indicates a completed packet, and also indicates that all
packets preceding that packet have been put in the output FIFO.
7.2.5
Overview of On-Chip Transmit Modes
Transmit mode is used to refer to a set of configurations that support some of the
transmit path offloads. These modes are updated and controlled with the transmit
descriptors.
There are three types of transmit modes:
• Legacy mode
• Extended mode
• Segmentation mode
The first mode (legacy) is an implied mode as it is not explicitly specified with a context
descriptor. This mode is constructed by the device from the first and last descriptors of
a legacy transmit and from some internal constants. The legacy mode enables insertion
of one checksum.
The other two modes are indicated explicitly by a transmit context descriptor. The
extended mode is used to control the checksum offloading feature for packet
transmission. The segmentation mode is used to control the packet segmentation
capabilities of the device. The TSE bit, in the context descriptor, selects which mode is
updated, that is, extended mode or segmentation mode. The extended and
segmentation modes enable insertion of two checksums. In addition, the segmentation
mode adds information specific to the segmentation capability.
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