kstat_create(9F)

NAME

     kstat_create - create and initialize a new kstat

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)

PARAMETERS

     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  do  not  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 sig-
           nificant.

     class The general class that this kstat belongs to. The fol-
           lowing 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
                 Allows more than one data record per kstat.

           KSTAT_TYPE_INTR
                 Interrupt; only one data record per kstat.

           KSTAT_TYPE_IO
                 I/O; only one data record per kstat

     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 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  dor-
                 mant;  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_create() allocates and performs necessary system  ini-
     tialization  of  a kstat(9S) structure. kstat_create() allo-
     cates memory for the entire kstat (header plus  data),  ini-
     tializes  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.

CONTEXT

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

EXAMPLES

     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 */
             kstat_install(ksp);
          }

SEE ALSO

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

     Writing Device Drivers