Re: [PATCH] Futexes IV (Fast Lightweight Userspace Semaphores)

Linus Torvalds
2002-03-10T19:42:53Z

In article <E16jVSZ-0008FH-00@the-village.bc.nu>,
Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
>
>So if anything its just not worth the effort of breaking the 386 setup
>either 8). 386 SMP is a different issue but I don't see any lunatics doing
>a 386 based sequent port thankfully.

Since the only person that comes to mind that would be crazy enough to
even _try_ to use Linux on 386-SMP is you, Alan, I'm really relieved to
hear you say that ;)

And no, it's not worth discontinuing i386 support. It just isn't
painful enough to maintain.

Note that the i386 has _long_ been a "stepchild", though: because of the
lack of WP, the kernel simply doesn't do threaded MM correctly on a 386.
Never has, and never will.

However, the known "incorrect" case is so obscure that it's not even an
issue - although I suspect that it means that you should not let
untrusted users run on a i386 server machine that contains any sensitive
data. I could cerrtainly come up with exploits that would work at least
in theory (whether they are workable in practice I don't know).

Using i386's for network servers is fine, of course. Just don't use
them for cpu farms (not that I think anybody is - it takes quite a big
farm of i386 machines to equal even _one_ PII ;)

Linus