kbuild: fix interaction of CONFIG_IKCONFIG and KCONFIG_CONFIG

If you try to build a kernel with KCONFIG_CONFIG set (to a value
not equal to .config) and that 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.

because the kernel/Makefile contains a direct reference to .config.

This issue 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>
Reviewed-by: Michal Marek <mmarek@suse.cz>
Signed-off-by: Michal Marek <mmarek@suse.cz>

1 files changed, 1 insertions, 0 deletions

diff --git a/Makefile b/Makefile
index 6619720f50dd..ee77a3d88e0a 100644
--- a/Makefile
+++ b/Makefile
@@ -224,6 +224,7 @@ ifeq ($(ARCH),m68knommu)
 endif
 
 KCONFIG_CONFIG  ?= .config
+export KCONFIG_CONFIG
 
 # SHELL used by kbuild
 CONFIG_SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \