Device and Network Interfaces 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 reconfiguration or replacement.
In order for the resume operation to succeed, it is impor-
tant 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 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 dev-
ices 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 per-
forming critical or time-sensitive operations (such as
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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 opera-
tion 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 con-
nections will continue to operate transparently on a resume
operation; those applications that do not will likely fail.
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWcpr
Interface stability Unstable
SEE ALSO
dtpower(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 hardware platforms. Please see the book Using Power
Management for a complete list of platforms that support
system Power Management. See uname(2) to programatically
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Device and Network Interfaces cpr(7)
determine if the machine supports suspend-resume.
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