module_info(D4)module_info(D4)NAMEmodule_info - STREAMS driver and module information structure
SYNOPSIS
#include <sys/types.h>
#include <sys/conf.h>
#include <sys/stream.h>
#include <sys/ddi.h>
DESCRIPTION
When a module or driver is declared, several identification and limit
values can be set. These values are stored in the module_info structure.
These values are used to initialize the module's or driver's queues when
they are created.
USAGE
After the initial declaration, the module_info structure is intended to
be read-only. However, the flow control limits (mi_hiwat and mi_lowat)
and the packet size limits (mi_minpsz and mi_maxpsz) are copied to the
queue(D4) structure, where they may be modified.
There may be one module_info structure per read and write queue, or the
driver or module may use the same module_info structure for both the read
and write queues.
Structure Definitions
The module_info structure contains the following members:
ushort_t mi_idnum; /* module ID number */
char *mi_idname; /* module name */
long mi_minpsz; /* minimum packet size */
long mi_maxpsz; /* maximum packet size */
ulong_t mi_hiwat; /* high water mark */
ulong_t mi_lowat; /* low water mark */
The mi_idnum field is a unique identifier for the driver or module that
distinguishes the driver or module from the other drivers and modules in
the system.
The mi_idname field points to the driver or module name. The constant
FMNAMESZ limits the length of the name, not including the terminating
NULL. It is currently set to eight characters.
The mi_minpsz field is the default minimum packet size for the driver or
module queues. This is an advisory limit specifying the smallest message
that can be accepted by the driver or module.
The mi_maxpsz field is the default maximum packet size for the driver or
module queues. This is an advisory limit specifying the largest message
that can be accepted by the driver or module.
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module_info(D4)module_info(D4)
The mi_hiwat field is the default high water mark for the driver or
module queues. This specifies the number of bytes of data contained in
messages on the queue such that the queue is considered full and hence
flow-controlled.
The mi_lowat field is the default low water mark for the driver or module
queues. This specifies the number of bytes of data contained in messages
on the queue such that the queue is no longer flow-controlled.
REFERENCESqueue(D4)
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