comp.os.minix | Google Groups

What would you like to see most in minix?

Linus Benedict Torvalds <torva...@klaava.helsinki.fi>

In article <1991Aug25.234450.22...@nntp.hut.fi> j...@cs.HUT.FI (Jyrki Kuoppala) writes:
>> [re: my post about my new OS]

>Tell us more! Does it need a MMU?

Yes, it needs a MMU (sorry everybody), and it specifically needs a
386/486 MMU (see later).

>>PS. Yes - it's free of any minix code, and it has a multi-threaded fs.
>>It is NOT protable (uses 386 task switching etc)

>How much of it is in C? What difficulties will there be in porting?
>Nobody will believe you about non-portability ;-), and I for one would
>like to port it to my Amiga (Mach needs a MMU and Minix is not free).

Simply, I'd say that porting is impossible. It's mostly in C, but most
people wouldn't call what I write C. It uses every conceivable feature
of the 386 I could find, as it was also a project to teach me about the
386. As already mentioned, it uses a MMU, for both paging (not to disk
yet) and segmentation. It's the segmentation that makes it REALLY 386
dependent (every task has a 64Mb segment for code & data - max 64 tasks
in 4Gb. Anybody who needs more than 64Mb/task - tough cookies).

It also uses every feature of gcc I could find, specifically the __asm__
directive, so that I wouldn't need so much assembly language objects.
Some of my "C"-files (specifically mm.c) are almost as much assembler as
C. It would be "interesting" even to port it to another compiler (though
why anybody would want to use anything other than gcc is a mystery).

Unlike minix, I also happen to LIKE interrupts, so interrupts are
handled without trying to hide the reason behind them (I especially like
my hard-disk-driver. Anybody else make interrupts drive a state-
machine?). All in all it's a porters nightmare.

>As for the features; well, pseudo ttys, BSD sockets, user-mode
>filesystems (so I can say cat /dev/tcp/kruuna.helsinki.fi/finger),
>window size in the tty structure, system calls capable of supporting
>POSIX.1. Oh, and bsd-style long file names.

Most of these seem possible (the tty structure already has stubs for
window size), except maybe for the user-mode filesystems. As to POSIX,
I'd be delighted to have it, but posix wants money for their papers, so
that's not currently an option. In any case these are things that won't
be supported for some time yet (first I'll make it a simple minix-
lookalike, keyword SIMPLE).

Linus (torva...@kruuna.helsinki.fi)

PS. To make things really clear - yes I can run gcc on it, and bash, and
most of the gnu [bin/file]utilities, but it's not very debugged, and the
library is really minimal. It doesn't even support floppy-disks yet. It
won't be ready for distribution for a couple of months. Even then it
probably won't be able to do much more than minix, and much less in some
respects. It will be free though (probably under gnu-license or similar).