Linus Torvalds wrote:
>
>
> On Wed, 11 Apr 2001, Bernd Schmidt wrote:
> See? Do you see why a "memory" clobber is _not_ comparable to a "ax"
> clobber? And why that non-comparability makes a memory clobber equivalent
> to a read-modify-write cycle?
I had to think about this, so I'll explain it
Linus Torvalds wrote:
On Wed, 11 Apr 2001, Bernd Schmidt wrote:
See? Do you see why a "memory" clobber is _not_ comparable to a "ax"
clobber? And why that non-comparability makes a memory clobber equivalent
to a read-modify-write cycle?
I had to think about this, so I'll explain it a
On Wed, 11 Apr 2001, Bernd Schmidt wrote:
> >
> > The example in there compiles out-of-the box and is much easier to
> > experiment on than the whole kernel :-)
>
> That example seems to fail because a "memory" clobber only tells the compiler
> that memory is written, not that it is read.
The
On Wed, 11 Apr 2001, Andreas Franck wrote:
> Hello David,
>
> > I've been discussing it with some other kernel and GCC people, and they
> > think
> > that only "memory" is required.
>
> Hmm.. I just looked at my GCC problem report from December, perhaps you're
> interested, too:
>
>
Hello David,
> I've been discussing it with some other kernel and GCC people, and they
> think
> that only "memory" is required.
Hmm.. I just looked at my GCC problem report from December, perhaps you're
interested, too:
http://gcc.gnu.org/ml/gcc-bugs/2000-12/msg00554.html
The example in
I've been discussing it with some other kernel and GCC people, and they think
that only "memory" is required.
> What are the reasons against mentioning sem->count directly as a "=m"
> reference? This makes the whole thing less fragile and no more dependent
> on the memory layout of the
Hello David and people,
> I've just consulted with one of the gcc people we have here, and he says
> that
> the '"memory"' constraint should do the trick.
>
> Do I take it that that is actually insufficient?
I don't remember exactly, it's been a while, but I think it was not
sufficient when I
> I'd like you to look over it. It seems newer GCC's (snapshots and the
> upcoming 3.0) will be more strict when modifying some values through
> assembler-passed pointers - in this case, the passed semaphore structure got
> freed too early, causing massive stack corruption on early bootup.
>
>
Here's the RW semaphore patch again (rwsem2.diff) with a fallback to spinlocks
if XADD/CMPXCHG aren't available.
I've put the two implementations in separate headers as suggested.
David
diff -uNr linux-2.4.3/arch/i386/config.in linux/arch/i386/config.in
--- linux-2.4.3/arch/i386/config.in
Here's the RW semaphore patch again (rwsem2.diff) with a fallback to spinlocks
if XADD/CMPXCHG aren't available.
I've put the two implementations in separate headers as suggested.
David
diff -uNr linux-2.4.3/arch/i386/config.in linux/arch/i386/config.in
--- linux-2.4.3/arch/i386/config.in
I'd like you to look over it. It seems newer GCC's (snapshots and the
upcoming 3.0) will be more strict when modifying some values through
assembler-passed pointers - in this case, the passed semaphore structure got
freed too early, causing massive stack corruption on early bootup.
The
Hello David and people,
I've just consulted with one of the gcc people we have here, and he says
that
the '"memory"' constraint should do the trick.
Do I take it that that is actually insufficient?
I don't remember exactly, it's been a while, but I think it was not
sufficient when I came
I've been discussing it with some other kernel and GCC people, and they think
that only "memory" is required.
What are the reasons against mentioning sem-count directly as a "=m"
reference? This makes the whole thing less fragile and no more dependent
on the memory layout of the structure.
Hello David,
I've been discussing it with some other kernel and GCC people, and they
think
that only "memory" is required.
Hmm.. I just looked at my GCC problem report from December, perhaps you're
interested, too:
http://gcc.gnu.org/ml/gcc-bugs/2000-12/msg00554.html
The example in there
On Wed, 11 Apr 2001, Andreas Franck wrote:
Hello David,
I've been discussing it with some other kernel and GCC people, and they
think
that only "memory" is required.
Hmm.. I just looked at my GCC problem report from December, perhaps you're
interested, too:
On Wed, 11 Apr 2001, Bernd Schmidt wrote:
The example in there compiles out-of-the box and is much easier to
experiment on than the whole kernel :-)
That example seems to fail because a "memory" clobber only tells the compiler
that memory is written, not that it is read.
The above
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