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drv_getparm(9f)

drv_getparm(9F)                Kernel Functions                drv_getparm(9F)



NAME
       drv_getparm - retrieve kernel state information

SYNOPSIS
       #include <sys/ddi.h>

       int drv_getparm(unsigned int parm, void *value_p);

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

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


       LBOLT      Read  the value of lbolt. lbolt is a clock_t that represents
                  the number of clock ticks  since  system  boot.  No  special
                  treatment  is  applied when this value overflows the maximum
                  value of the signed integral type clock_t. 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 indication 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
                  difference between two measurements of lbolt is significant.
                  It  is  used in this way inside the system kernel for timing
                  purposes.


       PPGRP      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.


       PPID       Read process identification number.


       PSID       Read process session identification number.


       TIME       Read time in seconds.


       UCRED      Return a pointer to the caller's credential structure.


       value_p    A pointer to the data space in which the value of the param‐
                  eter is to be copied.


DESCRIPTION
       Since  Solaris  2.6,  the  drv_getparm()  function has been replaced by
       ddi_get_lbolt(9F), ddi_get_time(9F), and ddi_get_pid(9F).


       The drv_getparm() 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 value_p.


       The drv_getparm() 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  value_p.  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  drv_getparm()  function returns 0 to indicate success, −1 to indi‐
       cate failure. The value stored in the space pointed to  by  value_p  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,
       PPGRP, PPID, PSID, TIME, UCRED, or UPROCP. Always check the return code
       when using this function.

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

SEE ALSO
       ddi_get_lbolt(9F), ddi_get_pid(9F), ddi_get_time(9F), buf(9S)


       Writing Device Drivers in Oracle Solaris 11.4



Oracle Solaris 11.4               11 Dec 2020                  drv_getparm(9F)
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