Hi Arnd,
On Wed, Jul 12, 2017 at 9:22 AM, Arnd Bergmann <a...@arndb.de> wrote:
> On Wed, Jul 12, 2017 at 8:57 AM, Geert Uytterhoeven
> <ge...@linux-m68k.org> wrote:
>> With gcc 4.1.2:
>>
>> mm/memory.o: In function `create_huge_pmd':
>> memory.c:(.text+0x93e): undefined reference to
>> `do_huge_pmd_anonymous_page'
>>
>> Converting transparent_hugepage_enabled() from a macro to a static
>> inline function reduced the ability of the compiler to remove unused
>> code.
>>
>> Fix this by marking create_huge_pmd() inline.
>>
>> Fixes: 16981d763501c0e0 ("mm: improve readability of
>> transparent_hugepage_enabled()")
>> Signed-off-by: Geert Uytterhoeven <ge...@linux-m68k.org>
>
> Acked-by: Arnd Bergmann <a...@arndb.de>
Thanks!
>> ---
>> Interestingly, create_huge_pmd() is emitted in the assembler output, but
>> never called.
>
> I've never seen this before either. I know that early gcc-4 compilers
> would do this
> when a function is referenced from an unused function pointer, but not with
> a compile-time constant evaluation. I guess that transparent_hugepage_enabled
> is just slightly more complex than it gcc-4.1 can handle here.
You did mention seeing it with mips-gcc-4.1 in the thread "[RFC] minimum gcc
version for kernel: raise to gcc-4.3 or 4.6?", but didn't provide any further
details. Finally I started seeing it myself for m68k ;-)
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
