On Sat, 17 Dec 2005, David Howells wrote:
>
> Linux supports a number of those archs. Amongst them are 68000 (TAS), arm (SWP
> I think), i386 (XCHG), and FRV (SWAP). I'm also looking at another that only
> has BSET/BCLR.
Don't bother putting i386 in that list.
Quite frankly, you've done it before, and I think it's intellectually
totally dishonest.
i386 does semaphores with a "lock decl". You CANNOT DO IT FASTER. I dare
you. Why the hell do you try to make it sound as if x86 would need this
new thing, when it absolutely does NOT need it.
Yes, x86 _also_ has an xchg instruction, but hey, that's a total
non-argument. We don't actually use that.
Of the other architectures you list, only ARM is really important. And no,
arm doesn't do swap. It does LL/SC (except they call it "ldrex/strex",
which I assume stands for "load/store with reservation and X just because
X is cool. Yeah, we're cool" (*)).
68k is dead. Nobody cares. So just say it outright: this is totally just a
FRV feature, and NOBODY ELSE IS IN THE LEAST INTERESTED.
Ok? Just to inject a little honesty here.
Linus
(*) Actually, some arm docs I found implies that "ex" stands for
"exclusive", but that leaves me wondering what the "r" stands for?
