Kernel Properties for Drivers     no-involuntary-power-cycles(9P)



NAME
     no-involuntary-power-cycles -  device  property  to  prevent
     involuntary power cycles

DESCRIPTION
     A device that might be damaged by power cycles should export
     the  boolean  (zero  length)  property no-involuntary-power-
     cycles to notify the system that all power  cycles  for  the
     device must be under the control of the device driver.


     The presence of this  property  prevents  power  from  being
     removed  from  a  device or any ancestor of the device while
     the device driver is detached, unless the device was  volun-
     tarily  powered off as a result of the device driver calling
     pmlowerpower(9F).


     The  presence  of  no-involuntary-power-cycles  also  forces
     attachment  of the device driver during a CPR suspend opera-
     tion and prevents the suspend from taking place, unless  the
     device  driver returns DISUCES when its detach(9E) entry
     point is called with DISUSPEND.


     The presence of no-involuntary-power-cycles does not prevent
     the  system  from  being  powered  off  due to a halt(1M) or
     uadmin(1M) invocation, except for CPR suspend.


     This property can be exported by a device that is not  power
     manageable, in which case power is not removed from the dev-
     ice or from any of its ancestors, even when the  driver  for
     the device and the drivers for its ancestors are detached.

EXAMPLES
     Example 1 Use of Property in Driver's Configuration File


     The following is an example of a no-involuntary-power-cycles
     entry in a driver's .conf file:


       no-involuntary-power-cycles=1;
            ...


     Example 2 Use of Property in attach() Function


     The following is an example of how the preceding .conf  file
     entry  would  be implemented in the attach(9E) function of a



SunOS 5.11          Last change: 22 Mar 2001                    1






Kernel Properties for Drivers     no-involuntary-power-cycles(9P)



     driver:


       xxattach(devinfot *dip, ddiattachcmdt cmd)
         {
          ...
              if (ddipropcreate(DIDEVTNONE, dip, DIPROPCANSLEP,
                  "no-involuntary-power-cycles", NUL, 0) != DIPROPSUCES)
                   goto failed;
          ...
          }


ATRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:



     
           ATRIBUTE TYPE               ATRIBUTE VALUE       
    
     Interface stability          Committed                   
    


SEE ALSO
     attributes(5),     pm(7D),      attach(9E),      detach(9E),
     ddipropcreate(9F)


     Writing Device Drivers























SunOS 5.11          Last change: 22 Mar 2001                    2