SVR5 and SCO OpenServer

uwput(D2mdi)

uwput -- receive messages from the upper STREAMS queue

Syntax

See put(D2str) for syntax, context, and general usage information about this entry point routine.

Usage

This function is the STREAMS upper write put(D2str) routine, called by the STREAMS module that is above the MDI driver to pass down one of the following:

MDI primitive; see Section D7mdi manual pages in Section D7mdi manual pages.
MDI data; see Section D4mdi manual pages in Section D4mdi manual pages
MDI ioctl; see Section 7mdi manual pages in Section 7mdi manual pages

MDI primitives and MDI ioctls should be processed immediately by the MDI driver, or the DLPI in HDK Technical Reference module will assume that the hardware is inactive.

MDI data should be queued on the MDI driver's STREAMS queue if the adapter is not immediately ready to transmit it. This data will be de-queued at interrupt time when the adapter is ready to send more frames. Queuing transmit data in this manner instead of dropping outgoing frames when the hardware is busy reduces the number of dropped frames. De-queuing the data from the interrupt routine means that no STREAMS write queue service routine is needed.

Do not put messages back on the queue with putbq(D3str).

NOTE: Do not delay processing of messages for too long, or txmon assumes that the hardware is inactive. Also, do not put messages back on a queue using putbq( ).

Frame loop back

If the network adapter hardware does not loop back messages that are bound for the following addresses then the MDI driver must loop the frame back to the MDI user:

The broadcast MAC address.
A multicast address in the multicast table, or any multicast address if all MCAs are set.
The adapter's MAC address.
All transmit frames if the adapter is in promiscuous mode.

Use the mdi_do_loopback(D3mdi) function to make the data looped back to the MAC user be indistinguishable from data received from the network.

Version applicability

mdi: 1, 2, 2.1 running with ddi: 7, 7mp, 8, 8mp.

References

mdi_do_loopback(D3mdi), mdi_valid_mca(D3mdi), Intro(MDI) (on OpenServer 6), Intro(7mdi) (on UnixWare 7.1.4), put(D2str)