Re: "do section mismatch check on full vmlinux" breaks powerpc build

On Wed, Jul 25, 2007 at 04:16:10PM -0500, Nathan Lynch wrote:

Hi Sam-

Sam Ravnborg wrote:

quoted

On Tue, Jul 24, 2007 at 05:41:05PM -0500, Nathan Lynch wrote:

quoted

2.6.23-rc1 breaks the build for 64-bit powerpc for me (using
maple_defconfig):

  LD      vmlinux.o
powerpc64-unknown-linux-gnu-ld: dynreloc miscount for
kernel/built-in.o, section .opd
powerpc64-unknown-linux-gnu-ld: can not edit opd Bad value
make: *** [vmlinux.o] Error 1

I narrowed it down to the following change to avoid the breakage:

diff --git a/include/linux/mm.h b/include/linux/mm.h
index c456c3a..2ea222f 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h

@@ -1246,7 +1246,7 @@ void drop_slab(void);
 extern int randomize_va_space;
 #endif
 
-__attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma);
+//__attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma);
 
 #endif /* __KERNEL__ */
 #endif /* _LINUX_MM_H */

So seems that something goes a bit fishy when using weak symbols and this trigges 
a binutils bug.

The above line was introdused in the following commit:

commit f269fdd1829acc5e53bf57b145003e5733133f2b
Author: David Howells [off-list ref]
Date:   Wed Sep 27 01:50:23 2006 -0700

    [PATCH] NOMMU: move the fallback arch_vma_name() to a sensible place

Thanks for looking into this.  Removing the "__attribute__((weak))"
from arch_vma_name's declaration in linux/mm.h unbreaks the build for
me.

Maybe it shouldn't matter, but it seems unusual to have the weak
attribute specified at the function's declaration.  I wasn't able to
find any examples of that for other weak functions in the kernel
(e.g. sched_clock).

Unfortunately removing the weak attribute uncovered that x86_64 has
two functions with the same name => link error.
Needs to have that sorted first out but ball is rolling.
(Se lkml for details)

	Sam