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Kernel Functions for Driversdrv_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 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 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 parameter 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Since the release of the Solaris 2.6 operating environment, the drv_getparm() function has been replaced by ddi_get_lbolt(9F), ddi_get_time(9F), and ddi_get_pid(9F).

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.

drv_getparm() 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

 

drv_getparm() returns 0 to indicate success, -1 to indicate 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

 

drv_getparm() can be called from user context only when using PPGRP, PPID, PSID, UCRED, or UPROCP. It can be called from user or interrupt 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


SunOS 5.9Go To TopLast Changed 24 Jun 1997

 
      
      
Copyright 2002 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms.