Sleeping Beauty - NetBSD on Modern Laptops, Jörg Sonnenberger

Modern laptops don't have APM support, just ACPI.  One way to handle suspending is to suspend-to-RAM of the live system.  The more long term suspend requires suspending to disk.

PMF is the new power management system for NetBSD.  It does device power management in layers.   This allows the system and hardware devices to be shutdown in a logical order and properly bail out if a problem is encountered.

It also powers down optional hardware that supports power save or turning off.

It polls devices like audio devices, network devices, etc to capture their state and restore the state on resume.

It implements an event interface that allows you to send event notifications to specific devices or the whole system.  Events that are already implemented include things like lid close/open, etc.

Much of the ACPI code in NetBSD was rewritten to support PMF.  The ACPI Embedded Controller code was rewritten to use a dedicated kernel thread for handling SCIs.

You can see all the slides here:
http://www.netbsd.org/gallery/presentations/joerg/asiabsdcon2008/powermanagement.html