On Wed, May 26, 2010 at 10:54:41AM +0100, David Howells wrote:

K.Prasad [off-list ref] wrote:

quoted

quoted

My understanding is weak function definitions must appear in a different C
file than their call sites to work on some toolchains.

Atleast, there are quite a few precedents inside the Linux kernel for
__weak functions being invoked from the file in which they are defined
(arch_hwblk_init, arch_enable_nonboot_cpus_begin and hw_perf_disable to
name a few).
Moreover the online GCC docs haven't any such constraints mentioned.

I've seen problems in this area.  gcc sometimes inlines a weak function that's
in the same file as the call point.

We've seen such behaviour even otherwise....even with noinline attribute
in place. I'm not sure if this gcc fix
(http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16922) helped correct the
behaviour, but the lesson has been to not trust a function to be
inlined/remain non-inline consistently.

David

Thanks,
K.Prasad