cpr - Suspend and resume module


     /platform/'uname -m'/kernel/misc/cpr


     The cpr module is a loadable  module  used  to  suspend  and
     resume  the  entire system. You may wish to suspend a system
     to save power or to power off temporarily for transport. The
     cpr  module should not be used in place of a normal shutdown
     when performing any hardware reconfiguration or replacement.
     In  order  for the resume operation to succeed, it is impor-
     tant that the hardware configuration remain the  same.  When
     the   system  is  suspended,  the  entire  system  state  is
     preserved in non-volatile storage until a  resume  operation
     is conducted.

     dtpower(1M) or  power.conf(4)  are  used  to  configure  the
     suspend-resume feature.

     The speed of suspend  and resume operations can  range  from
     15  seconds  to  several  minutes,  depending  on the system
     speed, memory size, and load.

     During resume operation, the SIGTHAW signal is sent  to  all
     processes  to  allow  them  to  do any special processing in
     response to suspend-resume operation. Normally  applications
     are  not  required  to  do any special processing because of
     suspend-resume,  but  some  specialized  processes  can  use
     SIGTHAW  to restore the state prior to suspend. For example,
     X can refresh the screen in response to SIGTHAW.

     In some cases the cpr module may be unable  to  perform  the
     suspend  operation.  If a system contains additional devices
     outside the standard shipped configuration, it  is  possible
     that  device  drivers for these additional devices might not
     support  suspend-resume   operations.  In  this  case,   the
     suspend  fails and an error message is displayed. These dev-
     ices must be removed or their device  drivers  unloaded  for
     the   suspend  operation  to  succeed.   Contact  the device
     manufacturer to obtain a new version of device  driver  that
     supports suspend-resume.

     A  suspend  may also fail when devices or processes are per-
     forming critical or time-sensitive operations (such as real-
     time operations). The system will remain in its current run-
     ning state. Messages reporting the failure will be displayed
     on the console and status returned to the caller.  Once  the
     system  is  successfully suspended the resume operation will
     succeed, barring external  influences  such  as  a  hardware
     Some network-based applications may fail  across  a  suspend
     and resume
      cycle. This largely depends on the underlying network  pro-
     tocol  and  the applications involved.  In general, applica-
     tions that retry and automatically  reestablish  connections
     will  continue to operate  transparently on a resume  opera-
     tion; those applications that do not will likely fail.


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

    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    | Availability                | SUNWcpr                     |
    | Interface stability         | Unstable                    |


     dtpower(1M) (OpenWindows  Reference  Manual),  pmconfig(1M),
     uadmin(1M), uadmin(2), power.conf(4), attributes(5)

     Using Power Management

     Writing Device Drivers


     Certain device operations  such  as  tape  and  floppy  disk
     activities  are not resumable due to the nature of removable
     media.  These activities are detected at suspend  time,  and
     must  be stopped before the suspend  operation will complete

     Suspend-resume is currently  supported only on a limited set
     of  hardware  platforms.  Please  see   the book Using Power
     Management for a complete list  of  platforms  that  support
     system  Power  Management.  See  uname(2) to programatically
     determine if the machine supports suspend-resume.

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