power management on embedded linux?

Does anyone have experience with power management on embedded linux systems?
Is it mature and working? I specifically need my platform to do a hibernate
where the system state is saved to a ram disk and then restored very quickly
to wake up.

I know there are alot of issues with getting various devices to sleep and
wake but I think we can handle that. I'm mostly interested in the kernel
itself.

Any tips are appreciated.

Thanks,
Clark


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