82583V Datasheet, PDF (115/374 Pages) Intel Corporation – Intel® 82583V GbE Controller

Inline Functions—82583V GbE Controller
Note:
7.1.2
Note:
Note:
7.1.3
Good packets are defined as those packets with no:
• CRC error
• Symbol error
• Sequence error
• Length error
• Alignment error
• Where carrier extension or RX_ERR errors are detected.
However, if the Store-Bad-Packet bit is set in the Device Control register (RCTL.SBP),
then bad packets that pass the filter function are stored in host memory. Packet errors
are indicated by error bits in the receive descriptor (RDESC.ERRORS). It is possible to
receive all packets, regardless of whether they are bad, by setting the promiscuous
enables and the Store-Bad-Packet bit.
CRC errors before the SFD are ignored. Every packet must have a valid SFD (RX_DV
with no RX_ER in the GMII/MII interface) in order to be recognized by the device (even
bad packets).
Receive Data Storage
Memory buffers pointed to by descriptors store packet data. Hardware supports the
following receive buffer sizes:
• 256B 512B 1024B 2048B 4096B 8192B 16384B
• FLXBUF x 1024B while FLXBUF=1,2,3,…15
Buffer size is selected by bit settings in the Receive Control register (RCTL.BSIZE,
RCTL.BSEX, RCTL.DTYP and RCTL. FLXBUF).
The 82583V (in legacy mode) places no alignment restrictions on receive memory
buffer addresses. This is desirable in situations where the receive buffer was allocated
by higher layers in the networking software stack, as these higher layers might have no
knowledge of a specific device's buffer alignment requirements.
Although alignment is completely unrestricted, it is highly recommended that software
allocate receive buffers on at least cache-line boundaries whenever possible.
The larger buffer sizes are only offered to provide compatibility with other silicon types.
Jumbo frames are not supported with the 82583V.
Legacy Receive Descriptor Format
A receive descriptor is a data structure that contains the receive data buffer address
and fields for hardware to store packet information. If the RFCTL.EXSTEN bit is clear
and the RCTL.DTYP equals 00b, the 82583V uses the Legacy Rx Descriptor as shown in
the following figure.
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