Intel 82550 Switch User Manual


 
78 Intel 8255x 10/100 Mbps Ethernet Controller Family Open Source Software Developer Manual
Host Software Interface
Default - 0 (disabled).
Recommended - 0.
Bit 1 - Broadcast Disable. When this bit is set, it disables the device from receiving any
frames with a broadcast address (address of all 1s). Promiscuous mode setting overrides
broadcast disable.
Default - 0 (off).
Recommended - 0.
Bit 0 - Promiscuous Mode. When this bit is set, it causes the device to receive all frames
regardless of their destination address.
Default - 0 (off).
Recommended - 0 (1 if promiscuous mode will be enabled).
BYTE 16.
Bits 7:0 - FC Delay Least Significant Byte. This byte is reserved on the 82557 and should be
set to 00h.
For the 82558 or 82559, this byte corresponds to the least significant byte of the flow control
delay field. This delay is used as the time parameter for the assembly of transmitted flow
control frames. The value is defined in slot time (512 bit time) resolution.
Default - 0 (82557 compatible).
Recommended - 0.
BYTE 17.
Bit 7:0 - FC Delay Most Significant Byte. This byte is reserved on the 82557 and should be set
to 40h.
For the 82558 or 82559, this byte corresponds to the most significant byte of the flow control
delay field. This delay is used as the time parameter for the assembly of transmitted flow
control frames.
Default: 01000000 (82557 compatible).
Recommended: 0.
BYTE 18.
Bit 3 - Long Receive OK. This bit is reserved on the 82557 and should be set to 0.
When this bit is set on the 82558 or 82559, the device considers received frames that have
a data field longer than 1500 bytes as good frames. The frames are still flagged as long in
the RFD status word but the OK bit is set. Software can pass the frame to the NOS if long
frames are supported.
Default - 0 (disabled).
Recommended - 0 (unless the device is used in a VLAN environment).
Bit 2 - Receive CRC Transfer. When this feature is enabled, the CSMA/CD block
transfers the CRC to host memory. If the CRC is not transferred to memory it is stripped.
The report of CRC and alignment error is reported immediately. Setting this bit disables
the stripping enable bit. Thus, if the frame is padded (the length is less than the byte
count), the frame will be transferred to memory as a whole, without stripping, even if
stripping is enabled.
Default - 0 (disabled).
Recommended - 0.
Bit 1 - Padding Enable. If this bit is set to 1, the device enables the padding mechanism. If
the byte count of a transmitted frame is less than the minimum frame length, a padding