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Name

Synopsis

#include <sys/types.h>
#include <sys/kstat.h>

kstat_t *kstat_create(char *module, int instance, char *name, char *class, uchar_t type, ulong_t ndata, uchar_t ks_flag);

Interface Level

Solaris DDI specific (Solaris DDI)

Arguments

module

The name of the provider’s module (such as "sd", "esp", ...). The "core" kernel uses the name "unix".

instance

The provider’s instance number, as from ddi_get_instance(9F) . Modules which don’t have a meaningful instance number should use 0.

name

A pointer to a string that uniquely identifies this structure. Only KSTAT_STRLEN - 1 characters are significant.

class

The general class that this kstat belongs to. The following classes are currently in use: disk, tape, net, controller, vm, kvm, hat, streams, kstat, and misc.

type

The type of kstat to allocate. Valid types are:

KSTAT_TYPE_NAMED

named - allows more than one data record per kstat

KSTAT_TYPE_INTR

interrupt - only one data record per kstat

KSTAT_TYPE_IO

I/O -

ndata

The number of type-specific data records to allocate.

flag

A bit-field of various flags for this kstat. flag is some combination of:

KSTAT_FLAG_VIRTUAL

Tells kstat_create() not to allocate memory for the kstat data section; instead, the driver will set the ks_data field to point to the data it wishes to export. This provides a convenient way to export existing data structures.

KSTAT_FLAG_WRITABLE

Makes the kstat’s data section writable by root.

KSTAT_FLAG_PERSISTENT

Indicates that this kstat is to be persistent over time. For persistent kstats, kstat_delete(9F) simply marks the kstat as dormant; a subsequent kstat_create() reactivates the kstat. This feature is provided so that statistics are not lost across driver close/open (such as raw disk I/O on a disk with no mounted partitions.)

Note: Persistent kstats cannot be virtual, since ks_data points to garbage as soon as the driver goes away.

Description

kstat_create() is used in conjunction with kstat_install(9F) to allocate and initialize a kstat(9S) structure. The method is generally as follows:

    kstat_t    *ksp;

    ksp = kstat_create(module, instance, name, class, type, ndata, flags);
    if (ksp) {
        /* ... provider initialization, if necessary */
        kstat_install(ksp);
    }

kstat_create() allocates and performs necessary system initialization of a kstat(9S) structure. kstat_create() allocates memory for the entire kstat (header plus data), initializes all header fields, initializes the data section to all zeroes, assigns a unique kstat ID (KID), and puts the kstat onto the system’s kstat chain. The returned kstat is marked invalid because the provider (caller) has not yet had a chance to initialize the data section.

After a successful call to kstat_create() the driver must perform any necessary initialization of the data section (such as setting the name fields in a kstat of type KSTAT_TYPE_NAMED ). Virtual kstats must have the ks_data field set at this time. The provider may also set the ks_update, ks_private, and ks_lock fields if necessary.

Once the kstat is completely initialized, kstat_install(9F) is used to make the kstat accessible to the outside world.

Return Values

Context

kstat_create() can be called from user or kernel context.

See Also

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