CPR(7)CPR(7)NAME
cpr - Suspend and resume module
SYNOPSIS
/platform/'uname -m'/kernel/misc/cpr
DESCRIPTION
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 reconfigura‐
tion or replacement. In order for the resume operation to succeed, it
is important 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 oper‐
ation. 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
devices must be removed or their device drivers unloaded for the sus‐
pend 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 performing
critical or time-sensitive operations (such as realtime operations).
The system will remain in its current running 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 reconfigu‐
ration.
Some network-based applications may fail across a suspend and resume
cycle. This largely depends on the underlying network protocol and the
applications involved. In general, applications that retry and auto‐
matically reestablish connections will continue to operate transpar‐
ently on a resume operation; those applications that do not will
likely fail.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────┬─────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────┼─────────────────┤
│Interface stability │ Unstable │
└─────────────────────┴─────────────────┘
SEE ALSOdtpower(1M) (OpenWindows Reference Manual), pmconfig(1M), uadmin(1M),
uadmin(2), power.conf(4), attributes(5)
Using Power Management
Writing Device Drivers
NOTES
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 successfully.
Suspend-resume is currently supported only on a limited set of hard‐
ware platforms. Please see the book Using Power Management for a com‐
plete list of platforms that support system Power Management. See
uname(2) to programatically determine if the machine supports suspend-
resume.
May 7, 2001 CPR(7)
