drv_getparm(9F) Kernel Functions for Drivers drv_getparm(9F)NAMEdrv_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 decreas‐
ing 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 differ‐
ence between two measurements of lbolt is significant. It is
used in this way inside the system kernel for timing pur‐
poses.
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 the release of the Solaris 2.6 operating environment, 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drv_getparm() function has been replaced by ddi_get_lbolt(9F),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 ALSOddi_get_lbolt(9F), ddi_get_pid(9F), ddi_get_time(9F), buf(9S)
Writing Device Drivers
SunOS 5.11 4 Sep 2009 drv_getparm(9F)
