|CPR(4)||Device and Network Interfaces||CPR(4)|
cprmodule 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
cprmodule 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 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.
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
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
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 devices 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 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 reconfiguration.
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 automatically reestablish connections will continue to operate transparently on a resume operation; those applications that do not will likely fail.
Writing Device Drivers
Suspend-resume is currently supported only on a limited set of hardware platforms.
|January 12, 2020||OmniOS|