[PATCH v1 4/8] selftests/nolibc: add extra config file customize support

[Zhangjin Wu]

The default DEFCONFIG_<ARCH> may not always work for all architectures,
some architectures require to add extra kernel config options, this adds
a new 'extconfig' target for this requirement.

It allows to customize extra kernel config options via the common
common.config and the architecture specific <ARCH>.config, at last
trigger 'allnoconfig' to let them take effect with missing config
options as disabled.

The scripts/kconfig/merge_config.sh tool is used to merge the extra
config files.

Suggested-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/lkml/67eb70d4-c9ff-4afc-bac7-7f36cc2c81bc@xxxxxxxx/
Signed-off-by: Zhangjin Wu <falcon@xxxxxxxxxxx>
---
 tools/testing/selftests/nolibc/Makefile | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/testing/selftests/nolibc/Makefile b/tools/testing/selftests/nolibc/Makefile
index f42adef87e12..08a5ca5f418b 100644
--- a/tools/testing/selftests/nolibc/Makefile
+++ b/tools/testing/selftests/nolibc/Makefile
@@ -39,6 +39,9 @@ DEFCONFIG_s390       = defconfig
 DEFCONFIG_loongarch  = defconfig
 DEFCONFIG            = $(DEFCONFIG_$(ARCH))
 
+# extra kernel config files under configs/, include common + architecture specific
+EXTCONFIG            = common.config $(ARCH).config
+
 # optional tests to run (default = all)
 TEST =
 
@@ -162,6 +165,10 @@ initramfs: nolibc-test
 defconfig:
 	$(Q)$(MAKE) -C $(srctree) ARCH=$(ARCH) CC=$(CC) CROSS_COMPILE=$(CROSS_COMPILE) mrproper $(DEFCONFIG) prepare
 
+extconfig:
+	$(Q)$(srctree)/scripts/kconfig/merge_config.sh -O "$(srctree)" -m "$(srctree)/.config" $(foreach c,$(EXTCONFIG),$(wildcard $(CURDIR)/configs/$c))
+	$(Q)$(MAKE) -C $(srctree) ARCH=$(ARCH) CC=$(CC) CROSS_COMPILE=$(CROSS_COMPILE) KCONFIG_ALLCONFIG="$(srctree)/.config" allnoconfig
+
 kernel: initramfs
 	$(Q)$(MAKE) -C $(srctree) ARCH=$(ARCH) CC=$(CC) CROSS_COMPILE=$(CROSS_COMPILE) $(IMAGE_NAME) CONFIG_INITRAMFS_SOURCE=$(CURDIR)/initramfs
 
-- 
2.25.1