[RFC XEN PATCH] build: Require explicit .config update

[Anthony PERARD <anthony@xxxxxxxxxxxxxx>]

From: Anthony PERARD <anthony.perard@xxxxxxxxxx>

It is sometime unwelcome for the config of the hypervisor to change.

Make output will be something like that:
  tools/kconfig/conf  --syncconfig Kconfig

  *** The configuration requires explicit update.

  make[2]: *** [/xen.git/xen/tools/kconfig/Makefile:73: syncconfig] Error 1
    GEN     Makefile
  /xen.git/xen/Rules.mk:19: include/config/auto.conf: No such file or directory
  make[2]: *** No rule to make target 'include/config/auto.conf'.  Stop.
  make[1]: *** [/xen.git/xen/Makefile:620: xen] Error 2
  make: *** [/xen.git/xen/Makefile:179: __sub-make] Error 2

This also prevent update when the toolchain change and change CONFIG_*
values like CONFIG_GCC_VERSION.

Proposed-by: during design session
Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---

During the design session, the proposal was to compare .config before
and after syncconfig. But maybe KCONFIG_NOSILENTUPDATE is enough?

---
 xen/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/Makefile b/xen/Makefile
index 49da79e10f..efeaaa557c 100644
--- a/xen/Makefile
+++ b/xen/Makefile
@@ -379,7 +379,7 @@ $(KCONFIG_CONFIG): tools_fixdep
 # The syncconfig should be executed only once to make all the targets.
 include/config/%.conf include/config/%.conf.cmd: $(KCONFIG_CONFIG)
        $(Q)rm -f include/config/auto.conf
-       $(Q)$(MAKE) $(build)=tools/kconfig syncconfig
+       $(Q)$(MAKE) $(build)=tools/kconfig syncconfig KCONFIG_NOSILENTUPDATE=1
 
 ifeq ($(CONFIG_DEBUG),y)
 CFLAGS += -O1
-- 
Anthony PERARD