Suspend-Safe/Suspend-Unsafe Devices - Sun Microsystems Sun Enterprise 10000 Dynamic Reconfiguration User Manual

A quiescent failure due to real-time processes or open suspend-unsafe devices is
known as a forcible condition. You have the option of performing either a retry or
forced retry. When you force the quiescence, you give the operating environment
permission to continue with the quiescence even if forcible conditions are still
present.
Caution – Exercise care when using the force option.
If a real-time process is running, determine if suspending the process would produce
an adverse effect on the functions performed by the process. If not, you can force the
operating environment to quiesce. (To force a quiescence, you can either click the
Force button within Hostview as described in "To Detach a Board With Hostview"
on page 32, or enter the complete_detach command with the force option within
the dr(1M) shell application. Otherwise, you can abort the operation and try again
later.
If any suspend-unsafe device is open and cannot be closed, you can manually
suspend the device, and then force the operating environment to quiesce. After the
operating environment resumes, you can manually resume the device (see
"Suspend-Safe/Suspend-Unsafe Devices" on page 12).
If the operating environment fails to quiesce, pay close attention to the reasons for
the failure. If the operating environment encountered a transient condition—a failure
to suspend a process—you can try the operation again. If, however, the condition(s)
requires your approval (for example, a real-time process is running) or intervention
(for example, a suspend-unsafe device is open), you can force the operating
environment to quiesce.

Suspend-Safe/Suspend-Unsafe Devices

A suspend-safe device is one that does not access the domain centerplane (for
example, it does not access memory or interrupt the system) while the operating
environment is quiesced. A driver is considered suspend-safe if it supports
operating environment quiescence (suspend/resume) and guarantees that when a
suspend request is successfully completed, the device that the driver manages will
not attempt to access the domain centerplane, even if the device is open when the
suspend request is made. All other I/O devices are suspend-unsafe when open.
Note – At the time of this printing, the drivers released by Sun Microsystems™ that
are known to be suspend-safe are st, sd, isp, esp, fas, sbus, pci, pei-pci, qfe,
hme (SunFastEthernet™), nf (NPI-FDDI), qe (Quad Ethernet), le (Lance Ethernet),
the SSA drivers (soc, pln, and ssd), and the Sun StorEdge™ A5000 drivers (sf,
socal, ses).
12 Sun Enterprise 10000 Dynamic Reconfiguration User Guide • February 2000