Messages in this thread | | | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] Futexes IV (Fast Lightweight Userspace Semaphores) | Date | 8 Mar 2002 16:03:33 -0800 |
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Followup to: <Pine.LNX.4.33.0203081532550.4421-100000@penguin.transmeta.com> By author: Linus Torvalds <torvalds@transmeta.com> In newsgroup: linux.dev.kernel > > You don't understand. This has nothing to do with lock holders, or > anything else. > > I'm saying that we map in a page at a magic offset (just above the stack), > and that page contains the locking code. > > For 386 CPU's (where only UP matters), we can trivially come up with a > lock that doesn't use cmpxchg8b and that isn't SMP-safe. It might even go > into the kernel every time if it has to - ie it _works_, it just isn't > optimal. >
Okay, I'll say it and be impopular...
Perhaps it's time to drop i386 support?
It seems to me that the i386 support has been around mostly on a "until we have a reason to do otherwise" basis, but perhaps this is the reason?
There certainly are enough little, nagging reasons... CMPXCHG, BSWAP, and especially WP...
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