Re: GCC-4 problems

[Paul M. <le...@li...>]

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..

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.

You may also want to check with gcc-4.2.x.

> 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?