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   7 .TH CPR 7 "May 13, 2017"
   8 .SH NAME
   9 cpr \- Suspend and resume module
  10 .SH SYNOPSIS
  11 .LP
  12 .nf
  13 \fB/platform/'uname -m'/kernel/misc/cpr\fR
  14 .fi
  15 
  16 .SH DESCRIPTION
  17 .LP
  18 The \fBcpr\fR module is a loadable module used to suspend and resume the entire
  19 system. You may wish to suspend a system to save power or to power off
  20 temporarily for transport. The \fBcpr\fR module should not be used in place of
  21 a normal shutdown when performing any hardware reconfiguration or replacement.
  22 In order for the resume operation to succeed, it is important that the hardware
  23 configuration remain the same. When the system is suspended, the entire system
  24 state is preserved in non-volatile storage until a resume operation is
  25 conducted.
  26 .sp
  27 .LP
  28 \fBpmconfig\fR(1M) and \fBpower.conf\fR(4) are used to configure the
  29 suspend-resume feature.
  30 .sp
  31 .LP
  32 The speed of suspend and resume operations can range from 15 seconds to
  33 several minutes, depending on the system speed, memory size, and load.
  34 .sp
  35 .LP
  36 During resume operation, the \fBSIGTHAW\fR signal is sent to all processes to
  37 allow them to do any special processing in response to suspend-resume
  38 operation. Normally applications are not required to do any special processing
  39 because of suspend-resume, but some specialized processes can use
  40 \fBSIGTHAW\fR to restore the state prior to suspend. For example, \fBX\fR can
  41 refresh the screen in response to \fBSIGTHAW\fR.
  42 .sp
  43 .LP
  44 In some cases the \fBcpr\fR module may be unable to perform the suspend
  45 operation. If a system contains additional devices outside the standard shipped
  46 configuration, it is possible that device drivers for these additional devices
  47 might not support suspend-resume operations. In this case, the suspend fails
  48 and an error message is displayed. These devices must be removed or their
  49 device drivers unloaded for the suspend operation to succeed. Contact the
  50 device manufacturer to obtain a new version of device driver that supports
  51 suspend-resume.
  52 .sp
  53 .LP
  54 A suspend may also fail when devices or processes are performing critical or
  55 time-sensitive operations (such as realtime operations). The system will remain
  56 in its current running state. Messages reporting the failure will be displayed
  57 on the console and status returned to the caller. Once the system is
  58 successfully suspended the resume operation will succeed, barring external
  59 influences such as a hardware reconfiguration.
  60 .sp
  61 .LP
  62 Some network-based applications may fail across a suspend and resume cycle.
  63 This largely depends on the underlying network protocol and the applications
  64 involved.  In general, applications that retry and automatically reestablish
  65 connections will continue to operate transparently on a resume operation;
  66 those applications that do not will likely fail.
  67 .SH ATTRIBUTES
  68 .LP
  69 See \fBattributes\fR(5) for descriptions of the following attributes:
  70 .sp
  71 
  72 .sp
  73 .TS
  74 box;
  75 c | c
  76 l | l .
  77 ATTRIBUTE TYPE  ATTRIBUTE VALUE
  78 _
  79 Interface stability     Unstable
  80 .TE
  81 
  82 .SH SEE ALSO
  83 .LP
  84 \fBpmconfig\fR(1M),
  85 \fBuadmin\fR(1M), \fBuadmin\fR(2), \fBpower.conf\fR(4), \fBattributes\fR(5)
  86 .sp
  87 .LP
  88 \fIWriting Device Drivers\fR
  89 .SH NOTES
  90 .LP
  91 Certain device operations such as tape and floppy disk activities are not
  92 resumable due to the nature of removable media.  These activities are detected
  93 at suspend time, and must be stopped before the suspend operation will
  94 complete successfully.
  95 .sp
  96 .LP
  97 Suspend-resume is currently supported only on a limited set of hardware
  98 platforms.