"Non-volatile" OS ?

For the O.P's question I would suggest looking into a system that doesn't store everything back to non-volatile memory, but simply goes into a super low power hibernate mode, preserving RAM memory contents and CPU state at some small current usage.

A bit of power fail detect, power switching/charging circuitry, a decent battery should get you through a short interruption without trying to save all that state. Hopefully the OS could be minimally modified to deal with this.

A lot of this kind of circuitry has been put out for the laptop and low power embedded market (think PDA, cell phone processors and battery circuits) and can be adapted to embedded uses.

I do not know. It is used in cell phones and PDAs, so it should be more geared towards this sort of functionality than the more traditional OSes. For maximum power saving, these sort of devices have to be able to basically shut down completely - and are then woken up on some external signal or event.

Regards Anton Erasmus

Obviously you will need to augment any OS with suitable logic for save and resume. Given you earlier comment about recovering in milliseconds, I suggest a combination of

1. enough storage energy to ride out transient outages when millisecond-type response is needed, and
2. application-level save and restore functions for orderly shutdown and restoration for longer outages. I would not expect the longer outages to be restored in milliseconds.

Thad

Hmm, I know at least two RTOS which provide a resume to the state before power-down (my old employer ENEA and my new ones Sciopta).

But I am sure other provide similar features.

If you want a fully automatic "hibernation", a small PC is the solution.

Sciopta (and OSE :-) support a semi-automatic version. Means it is you responsibility to get the processes into a state for power-down and make some kind of checksum over the saved data. On power-up you may re-check and re-init certain peripheral (which is done by the BIOS in a PC) than tell the RTOS that you did a resume rather than a cold-boot. This is used e.g. in BlueTooth chips where the ARM inside is most of the time not powered.