I think it's impossible to write an operating system in Perl because Perl does not contain any syntax to manage privilege levels. If the applications of this hypothetical operating system would be written in Perl too it could be possible to dispense with privilege by using lexicals. But there are no constructs in the language to deal with interrupts. And that is fatal even to a pure Perl operating system. BTW I think someone had (for a laugh) compiled perl as a linux kernel module. Has anyone URLs?