linkblk(D4)                                              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)





                           Copyright 1994 Novell, Inc.               Page 1

      linkblk(D4)                                              linkblk(D4)


      NOTICES
         Portability
            All processors













































                          Copyright 1994 Novell, Inc.               Page 2