[PATCH v3 3/7] selftests/nolibc: add extra configs customize support

[Zhangjin Wu <falcon@tinylab.org>]

The default DEFCONFIG_<ARCH> may not always work for all architectures,
some architectures require to add extra kernel config options, this
allows to add extra options in the defconfig target.

Based on the .config generated from DEFCONFIG_<ARCH>, It allows to
customize extra kernel config options via both 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@weissschuh.net>
Link: https://lore.kernel.org/lkml/67eb70d4-c9ff-4afc-bac7-7f36cc2c81bc@t-8ch.de/
Reviewed-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Zhangjin Wu <falcon@tinylab.org>
---
 tools/testing/selftests/nolibc/Makefile | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/testing/selftests/nolibc/Makefile b/tools/testing/selftests/nolibc/Makefile
index f42adef87e12..9576f1a0a98d 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 =
 
@@ -161,6 +164,8 @@ initramfs: nolibc-test
 
 defconfig:
 	$(Q)$(MAKE) -C $(srctree) ARCH=$(ARCH) CC=$(CC) CROSS_COMPILE=$(CROSS_COMPILE) mrproper $(DEFCONFIG) prepare
+	$(Q)$(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