On 25/12/2015 02:34, Josh Triplett wrote:
> On Thu, Dec 24, 2015 at 01:12:11PM +0100, Mickaël Salaün wrote:
>> Fix build error by generating elfcore.o only when ELF_CORE (depending on
>> COREDUMP) is selected:
>>
>> arch/x86/um/built-in.o: In function `elf_core_write_extra_phdrs':
>> (.text+0x3e62): undefined reference to `dump_emit'
>> arch/x86/um/built-in.o: In function `elf_core_write_extra_data':
>> (.text+0x3eef): undefined reference to `dump_emit'
>>
>> Fixes: 5d2acfc7b974 ("kconfig: make allnoconfig disable options behind EMBEDDED and EXPERT")
>> Signed-off-by: Mickaël Salaün <mic@digikod.net>
>> Cc: Jeff Dike <jdike@addtoit.com>
>> Cc: Richard Weinberger <richard@nod.at>
>> Cc: Josh Triplett <josh@joshtriplett.org>
>> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
>> Cc: Michal Marek <mmarek@suse.cz>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> 
> It looks like ELF_CORE depends on COREDUMP, but not on BINFMT_ELF.
> Should it?  What happens if you build this with ELF_CORE=y and
> BINFMT_ELF=n?  Does that configuration even make sense?

It build fine with ELF_CORE=y and BINFMT_ELF=n but does not seem useful. Nevertheless, it's the same for all architectures (cf. init/Kconfig): ELF_CORE only depends on COREDUMP.

 Mickaël