linkblk(D4)

NAME
     linkblk - STREAMS multiplexor link structure

SYNOPSIS
     #include <sys/stream.h>
     #include <sys/ddi.h>

DESCRIPTION
     The linkblk structure contains the information needed by a multiplexing
     driver to set up or take down a multiplexor link.

USAGE
     The linkblk structure is embedded in the M_DATA portion of the M_IOCTL
     messages generated from the following ioctl(2) calls: I_LINK, I_UNLINK,
     I_PLINK, and I_PUNLINK [see streamio(7)].

   Structure Definitions
     The linkblk structure contains the following members:

     queue_t  *l_qtop;  /* lower queue of top stream */
     queue_t  *l_qbot;  /* upper queue of bottom stream */
     int      l_index;  /* unique ID */
     The l_qtop field is a pointer to the lowest write queue in the upper
     stream.  In other words, it is the write queue of the multiplexing
     driver.  If the link is persistent across closes of the driver, then this
     field is set to NULL.

     The l_qbot field is a pointer to the upper write queue in the lower
     stream.  The lower stream is the stream being linked under the
     multiplexor.  The topmost read and write queues in the lower stream are
     given to the multiplexing driver to use for the lower half of its
     multiplexor processing.  The qinit(D4) structures associated with these
     queues are those specified for the lower processing in the multiplexing
     driver's streamtab(D4) structure.

     The l_index field is a unique ID that identifies the multiplexing link in
     the system.  The driver can use this as a key on which it can multiplex
     or de-multiplex.

REFERENCES
     datab(D4), iocblk(D4), ioctl(2), messages(D5), msgb(D4), qinit(D4),
     streamio(7), streamtab(D4)