1 CPR(7)                   Device and Network Interfaces                  CPR(7)
   2 
   3 NAME
   4      cpr - Suspend and resume module
   5 
   6 SYNOPSIS
   7      /platform/i86pc/kernel/misc/amd64/cpr
   8      /platform/sun4u/kernel/misc/sparcv9/cpr
   9 
  10 DESCRIPTION
  11      The cpr module is a loadable module used to suspend and resume the entire
  12      system.  You may wish to suspend a system to save power or to power off
  13      temporarily for transport.  The cpr module should not be used in place of
  14      a normal shutdown when performing any hardware reconfiguration or
  15      replacement.  In order for the resume operation to succeed, it is
  16      important that the hardware configuration remain the same.  When the
  17      system is suspended, the entire system state is preserved in non-volatile
  18      storage until a resume operation is conducted.
  19 
  20      pmconfig(1M) and power.conf(4) are used to configure the suspend-resume
  21      feature.
  22 
  23      The speed of suspend and resume operations can range from 15 seconds to
  24      several minutes, depending on the system speed, memory size, and load.
  25 
  26      During resume operation, the SIGTHAW signal is sent to all processes to
  27      allow them to do any special processing in response to suspend-resume
  28      operation.  Normally applications are not required to do any special
  29      processing because of suspend-resume, but some specialized processes can
  30      use SIGTHAW to restore the state prior to suspend.  For example, X can
  31      refresh the screen in response to SIGTHAW.
  32 
  33      In some cases the cpr module may be unable to perform the suspend
  34      operation.  If a system contains additional devices outside the standard
  35      shipped configuration, it is possible that device drivers for these
  36      additional devices might not support suspend-resume operations.  In this
  37      case, the suspend fails and an error message is displayed.  These devices
  38      must be removed or their device drivers unloaded for the suspend
  39      operation to succeed.  Contact the device manufacturer to obtain a new
  40      version of device driver that supports suspend-resume.
  41 
  42      A suspend may also fail when devices or processes are performing critical
  43      or time-sensitive operations (such as realtime operations).  The system
  44      will remain in its current running state.  Messages reporting the failure
  45      will be displayed on the console and status returned to the caller.  Once
  46      the system is successfully suspended the resume operation will succeed,
  47      barring external influences such as a hardware reconfiguration.
  48 
  49      Some network-based applications may fail across a suspend and resume
  50      cycle.  This largely depends on the underlying network protocol and the
  51      applications involved.  In general, applications that retry and
  52      automatically reestablish connections will continue to operate
  53      transparently on a resume operation; those applications that do not will
  54      likely fail.
  55 
  56 INTERFACE STABILITY
  57      Unstable
  58 
  59 SEE ALSO
  60      pmconfig(1M), uadmin(1M), uadmin(2), power.conf(4), attributes(5)
  61 
  62      Writing Device Drivers
  63 
  64 NOTES
  65      Certain device operations such as tape and floppy disk activities are not
  66      resumable due to the nature of removable media.  These activities are
  67      detected at suspend time, and must be stopped before the suspend
  68      operation will complete successfully.
  69 
  70      Suspend-resume is currently supported only on a limited set of hardware
  71      platforms.
  72 
  73 illumos                        January 12, 2020                        illumos