linkblk(D4)linkblk(D4)NAMElinkblk - 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.
REFERENCESdatab(D4), iocblk(D4), ioctl(2), messages(D5), msgb(D4), qinit(D4),
streamio(7), streamtab(D4)
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