Originally Posted by wawa
i think being able to compile on itself should be a feature or at least aim of a regular operating system. but im not sure amiga operating system components have all fulfilled this demand ever, especially as we hear that the build process is so complicated.
I has been possible since 1998 for the Amiga V40 operating system (Kickstart and Workbench) to compile itself on an Amiga.
After the build has finished, you can literally copy the disk images to floppy disks and install a blank hard drive using them (well, just creating a blank partition suits the same purpose). Don't forget to copy the AmigaOS source code to that blank partition, while you're at it.
You can then load the Kickstart ROM image appropriate for your machine, reboot it and boot from the recently installed natively-compiled Workbench. You can now restart the AmigaOS build again from scratch.
Some small portions are, however, not built natively. These concern printer drivers, aux-handler, mathieeedoubtrans.library and mathieeesingtrans.library. These require a cross-compiler (aux-handler is written in BCPL and needs the BCPL compiler, the math libraries need the math runtime library of the Green Hills 'C' compiler) or are so old that porting them to a modern compiler makes little sense (Alphacom, Diablo 630, Howtek Pixelmaster, Seiko 5300, Sharp JX-730, Tektronix 4693d, Toshiba P351SX, Xerox 4020, etc.). Replacements for aux-handler and the math libraries exist, and in this case work better than the originals
Even with these small omissions, it has been possible for some 18 years for the Amiga operating system to fully build itself on an Amiga. Well, that was mostly my
Amiga 3000UX with a 50 MHz 68060 CPU, but you get the general idea