Re: GCC-4 problems

[Manuel L. <ma...@ro...>]

Hi Paul,

On Mon, Mar 19, 2007 at 05:33:30PM +0900, Paul Mundt wrote:
> On Mon, Mar 19, 2007 at 09:27:57AM +0100, Manuel Lauss wrote:
> > When I build linux with GCC-4.x and enable CONFIG_CC_OPTIMIZE_FOR_SIZE
> > linking fails with this error:
> > 
> >   LD      .tmp_vmlinux1
> > kernel/built-in.o: In function '__cmpxchg_called_with_bad_pointer'
> > make[1]: *** [.tmp_vmlinux1] Error 1
> > make: *** [_all] Error 2
> > 
> > I tracked it to kernel/rtmutex.c, line 88:
> > 
> > #define rt_mutex_cmpxchg(l,c,n)	(cmpxchg(&l->owner, c, n) == c)
> > 
> > Apparently the "size" input value passed to cmpxchg is 
> > neither 4, 2 or 1 (tried a few others too but not sizeof(struct task_struct)).
> > Probably a compiler bug? (gcc-4.1.2, Gentoo)
> > 
> Have you tried 8? This was a problem before in another path..

no change. I'll see if I can find out the exact number somehow...
 
> Is CC_OPTIMIZE_FOR_SIZE the only thing you've set? You can try and avoid
> the __HAVE_ARCH_CMPXCHG in the gcc4 case if you want to fix it up, but I
> haven't hit this directly yet, so I'm hesitant to pull it in general for
> something that looks like a single compiler issue.

Yes; no funky debug options. Simply removing CC_OPTIMIZE_FOR_SIZE creates
a booting kernel.

> > Also, these exports need to be removed from sh_ksyms.c, they give
> > "undefined reference" errors:
> > __sdivsi3_i4i __udiv_qrnnd_16 __udivsi3_i4i
> > 
> Interesting. We'll kill those then. I'd also like to be rid of
> __udivdi3_* while we're at it, can you verify whether that causes you
> problems or not?

I removed all from __udivsi3 to __movstrSI16, no problems with GCC3 and 4.

Thanks,

-- 
 Manuel Lauss