ok, so for the sake of posterity, and anyone else searching... here's the answer.
it would appear that the EFI in the Mac Pro 1,1 that I have here, is as mentioned, 32bit.
None of the iso's of Ubuntu will boot from DVD or otherwise.
Except if you use that little bit of code hinted to above, and I have placed on my webserver in case anyone else ever wants it.
http://www.bienhaus.org/ubfix.zip
executable, on Ubuntu.
Pick whatever iso of the Ubuntu you want, place it next to this command, rename it to ub64.iso and run ubfix. (sudo ./ubfix) (rename; because the file name is hardcoded into the compiled command)
It will come back "done", and it has successfully modified the iso, and you can burn to a DVD and boot the Mac with it.
Next problem.
18, 19, and I presume 20, will install.
But they are silent about their work to put Grub on the boot disc, and from what I can find, it's actually Grub2 maybe?
At the very least, it's a 64bit Grub, and the system won't find it, load it, etc.
However!
16.04, 64bit, seems to have an older Grub, that if you recall installs right at the end of the purple screened install process.
THIS BOOTS BEAUTIFULLY!
My next challenge, was to see if I could put 19 (now for shits & giggles) on one of the other hard drives in this machine (it has 4), and get this 32bit Grub to boot it, without hurting 16.
The install went fine, and I picked the second hard drive and said don't touch the first one... sort of hoping it might update the Grub index on the first one.
No such luck.
So, anyhow -
The Mac now has 4 cores folding under 16, with success, and we're going to see if we can get the GPU running next.
But - if anyone has any expereince in editing the Grub records on the first hard drive, to allow it to let me select v19 that is installed on the second hard drive, I'd love to hear from you.
(just for fun)
