Kernel Functions for Drivers                      drvgetparm(9F)



NAME
     drvgetparm - retrieve kernel state information

SYNOPSIS
     #include 



     int drvgetparm(unsigned int parm, void *valuep);


INTERFACE LEVEL
     Architecture independent level 1 (DI/DKI).

PARAMETERS
     parm    The kernel parameter to be obtained. Possible values
             are:


     LBOLT     Read the value of lbolt. lbolt is a  clockt  that
               is  unconditionally  incremented  by  one  at each
               clock tick. No special treatment is  applied  when
               this  value  overflows  the  maximum  value of the
               signed integral type clockt.  When  this  occurs,
               its value will be negative, and its magnitude will
               be decreasing until it again passes zero.  It  can
               therefore not be relied upon to provide an indica-
               tion of the amount of time that passes  since  the
               last  system reboot, nor should it be used to mark
               an absolute time in the system. Only  the  differ-
               ence between two measurements of lbolt is signifi-
               cant. It is used in this  way  inside  the  system
               kernel for timing purposes.


     PGRP     Read the process group identification number. This
               number determines which processes should receive a
               HANGUP or BREAK signal when detected by a driver.


     UPROCP    Read the process table token value.


     PID      Read process identification number.


     PSID      Read process session identification number.


     TIME      Read time in seconds.





SunOS 5.11          Last change: 16 Jan 2006                    1






Kernel Functions for Drivers                      drvgetparm(9F)



     UCRED     Return a pointer to the caller's credential struc-
               ture.


     valuep    A pointer to the data space in which the value of
                the parameter is to be copied.


DESCRIPTION
     Since the release of the Solaris 2.6 operating  environment,
     the    drvgetparm()   function   has   been   replaced   by
     ddigetlbolt(9F), ddigettime(9F), and ddigetpid(9F).


     The drvgetparm() function verifies that parm corresponds to
     a  kernel  parameter  that may be read. If the value of parm
     does not correspond to  a  parameter  or  corresponds  to  a
     parameter  that  may not be read, -1 is returned. Otherwise,
     the value of the parameter  is  stored  in  the  data  space
     pointed to by valuep.


     The drvgetparm() function does not explicitly check to  see
     whether  the  device  has  the  appropriate context when the
     function is called and  the  function  does  not  check  for
     correct  alignment  in the data space pointed to by valuep.
     It is the responsibility of the driver writer  to  use  this
     function  only  when  it  is  appropriate  to  do  so and to
     correctly declare the data space needed by the driver.

RETURN VALUES
     The drvgetparm() function returns 0 to indicate success, -1
     to  indicate  failure. The value stored in the space pointed
     to by valuep  is  the  value  of  the  parameter  if  0  is
     returned,  or undefined if -1 is returned. -1 is returned if
     you specify a value other than  LBOLT,  PGRP,  PID,  PSID,
     TIME,  UCRED,  or  UPROCP. Always check the return code when
     using this function.

CONTEXT
     The drvgetparm() function can be called from  user  context
     only  when using PGRP, PID, PSID, UCRED, or UPROCP. It can
     be called from user, interrupt, or kernel context when using
     the LBOLT or TIME argument.

SEE ALSO
     ddigetlbolt(9F),    ddigetpid(9F),     ddigettime(9F),
     buf(9S)


     Writing Device Drivers




SunOS 5.11          Last change: 16 Jan 2006                    2