CPR(4) Device and Network Interfaces CPR(4)

NAME

cpr - Suspend and resume module

SYNOPSIS

/platform/i86pc/kernel/misc/amd64/cpr
/platform/sun4u/kernel/misc/sparcv9/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
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.

pmconfig(8) and power.conf(5) 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 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.

INTERFACE STABILITY

Unstable

SEE ALSO

uadmin(2), power.conf(5), attributes(7), pmconfig(8), uadmin(8)

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 hardware
platforms.

illumos January 12, 2020 illumos