Re: [PATCH] kbuild: fix interaction of CONFIG_IKCONFIG and KCONFIG_CONFIG

[Michal Marek <mmarek@suse.cz>]

On 26.11.2010 19:56, Ben Gardiner wrote:
> Change the use of .config in kernel/Makefile to $(KCONFIG_CONFIG).
>
> Currently, if you try to build a kernel with KCONFIG_CONFIG set (to a value
> not equal to .config) and the config file pointed to by KCONFIG_CONFIG sets
> CONFIG_IKCONFIG then the build will fail with:
>
> make[1]: *** No rule to make target `.config', needed by `kernel/config_data.gz'.  Stop.
>
> I think this has been present since the introduction of KCONFIG_CONFIG
> in 14cdd3c402bf7c66f0bcd76e290f0770a54a4b21.
>
> Signed-off-by: Ben Gardiner<bengardiner@nanometrics.ca>
> CC: Roman Zippel<zippel@linux-m68k.org>
> CC: Michal Marek<mmarek@suse.cz>
>
> ---
> based on 698fd6a2c3ca05ec796072defb5c415289a86cdc of
> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
>
>   kernel/Makefile |    2 +-
>   1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/Makefile b/kernel/Makefile
> index 0b5ff08..33e0a39 100644
> --- a/kernel/Makefile
> +++ b/kernel/Makefile
> @@ -121,7 +121,7 @@ $(obj)/configs.o: $(obj)/config_data.h
>   # config_data.h contains the same information as ikconfig.h but gzipped.
>   # Info from config_data can be extracted from /proc/config*
>   targets += config_data.gz
> -$(obj)/config_data.gz: .config FORCE
> +$(obj)/config_data.gz: $(KCONFIG_CONFIG) FORCE
>   	$(call if_changed,gzip)
>
>   quiet_cmd_ikconfiggz = IKCFG   $@

The problem is that KCONFIG_CONFIG is not exported in the top-level 
Makefile. If you want to use it in other Makefiles, you need to add the 
export.

Michal