man pages section 9: DDI and DKI Kernel Functions

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Updated: July 2014



kstat_create - create and initialize a new kstat


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

kstat_t *kstat_create(const char *ks_module, int ks_instance, 
     const char *ks_name, const char *ks_class, uchar_t ks_type, 
     ulong_t ks_ndata, uchar_t ks_flag);

Interface Level

Solaris DDI specific (Solaris DDI)



The name of the provider's module (such as “sd”, “esp”, ...). The “core” kernel uses the name “unix”.


The provider's instance number, as from ddi_get_instance(9F). Modules which do not have a meaningful instance number should use 0 .


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


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.


The type of kstat to allocate. Valid types are:


Allows more than one data record per kstat.


Interrupt; only one data record per kstat.


I/O; only one data record per kstat


The number of type-specific data records to allocate.


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


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.


Makes the kstat data section writable by root.


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.


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_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

If successful, kstat_create() returns a pointer to the allocated kstat. NULL is returned upon failure.


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


Example 1 Allocating and Initializing a kstat Structure

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

See also

kstat(3KSTAT), ddi_get_instance(9F), kstat_delete(9F), kstat_install(9F), kstat_named_init(9F), kstat (9S), kstat_named(9S)

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