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Message-ID: <alpine.LFD.0.999.0708112305170.30176@woody.linux-foundation.org>
Date: Sat, 11 Aug 2007 23:09:56 -0700 (PDT)
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Segher Boessenkool <segher@...nel.crashing.org>
cc: schwidefsky@...ibm.com, wjiang@...ilience.com,
wensong@...ux-vs.org, heiko.carstens@...ibm.com,
linux-kernel@...r.kernel.org, ak@...e.de, cfriesen@...tel.com,
netdev@...r.kernel.org, horms@...ge.net.au,
akpm@...ux-foundation.org, Chuck Ebbert <cebbert@...hat.com>,
davem@...emloft.net, zlynx@....org, Chris Snook <csnook@...hat.com>
Subject: Re: [PATCH] make atomic_t volatile on all architectures
On Sun, 12 Aug 2007, Segher Boessenkool wrote:
>
> Note that last line.
Segher, how about you just accept that Linux uses gcc as per reality, and
that sometimes the reality is different from your expectations?
"+m" works. We use it. It's better than the alternatives. Pointing to
stale documentation doesn't change anything.
The same is true of accesses through a volatile pointer. The kernel has
done that for a *loong* time (all MMIO IO is done that way), and it's
totally pointless to say that "volatile" isn't guaranteed to do what it
does. It works, and quite frankly, if it didn't work, it would be a gcc
BUG.
And again, this is not a "C standard" issue. It's a "sane implementation"
issue. Linux expects the compiler to be sane. If it isn't, that's not our
problem. gcc *is* sane, and I don't see why you constantly act as if it
wasn't.
Linus
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