On Sun, 2006-12-17 at 09:58 +0100, Ingo Molnar wrote:
> * Catalin Marinas <[EMAIL PROTECTED]> wrote:
>
> > Hi Ingo,
> >
> > On 16/12/06, Ingo Molnar <[EMAIL PROTECTED]> wrote:
> > >FYI, i'm working on integrating kmemleak into -rt. Firstly, i needed the
> > >fixes below when applying it ontop of 2.6.19-rt15.
> >
> > Do you need these fixes to avoid a compiler error? If yes, this is
> > caused by a bug in gcc-4.x. The kmemleak container_of macro has
> > protection for non-constant offsets passed to container_of but the
> > faulty gcc always returns true for builtin_contant_p, even when this
> > is not the case. Previous versions (3.4) or one of the latest 4.x gcc
> > don't have this bug.
> >
> > I wouldn't extend kmemleak to work around a gcc bug which was already
> > fixed.
>
> correct, i needed it for gcc 4.0.2. If you want this feature upstream,
> this has to be solved - no way are we going to phase out portions of
> gcc4. It's not hard as you can see it from my patch, non-static
> container_of is very rare. We do alot of other hackery to keep older
> compilers alive, and we only drop compiler support if some important
> feature really, really needs new gcc and a sane workaround is not
> possible.
If that's because of things like the dinky testcase below,
int main (int argc, char *argv[])
{
static int a[] = { __builtin_constant_p (argc) ? 1 : 0 };
return a[0];
}
AFAIK, no SuSE compiler can handle it. I just build/tested their latest
version,
gcc version 4.1.2 20061129 (prerelease) (SUSE Linux)
and it still can't deal with that without gcc41-rh198849.patch being
applied.
-Mike
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