Ubuntu on XServe G5, autostart after power failure

With OSX, one only needs go into System Prefs > Power Saving options.

WIth Ubuntu, this option isn't available on Apple hardware. Please don't start with "Why are you running Ubuntu....". It's an Xserve G5, and bigger companies like Apple and Microsoft tend to forget about their older creations. It's a server in an environment that needs support occasionally particularly in the form of updated software, and if we can't install modern OSX server variants on it, and cannot update Python, gcc and what not on the older installed OSX server version, go figure which OS automatically gets installed. So that is cleared up.

I'm primarily a software person, not a hardware person.

The problem here, I think, really comes down to the cloud of secrecy around Apple hardware back in the PowerPC days. With another server that isn't as old, and runs on intel architecture, I know enough low-level hardware science to find the right I/O controller manual from Intel and set the right registers.

With PowerPC architecture, the manuals for the controllers and what-nots in the XServe G5 have eluded me for 2 weeks, leading me to ask for help.

So, are there any of you hardware types, who have encountered this before? Or have good pointers where I should look?

Thank you.