[PATCH v2 04/14] selftests/nolibc: fix up O= option support

[Zhangjin Wu]

To avoid pollute the source code tree and avoid mrproper for every
architecture switch, the O= argument must be supported.

Both IMAGE and .config are from the building directory, let's use
objtree instead of srctree for them.

If no O= option specified, means building kernel in source code tree,
objtree should be srctree in such case.

Suggested-by: Willy Tarreau <w@xxxxxx>
Link: https://lore.kernel.org/lkml/ZK0AB1OXH1s2xYsh@xxxxxx/
Signed-off-by: Zhangjin Wu <falcon@xxxxxxxxxxx>
---
 tools/testing/selftests/nolibc/Makefile | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/nolibc/Makefile b/tools/testing/selftests/nolibc/Makefile
index f1c8e4a0f1b2..058e7be070ea 100644
--- a/tools/testing/selftests/nolibc/Makefile
+++ b/tools/testing/selftests/nolibc/Makefile
@@ -9,6 +9,9 @@ ifeq ($(srctree),)
 srctree := $(patsubst %/tools/testing/selftests/,%,$(dir $(CURDIR)))
 endif
 
+# add objtree for O= argument, required by IMAGE and .config
+objtree ?= $(srctree)
+
 ifeq ($(ARCH),)
 include $(srctree)/scripts/subarch.include
 ARCH = $(SUBARCH)
@@ -193,14 +196,14 @@ initramfs: nolibc-test
 
 # common macros for kernel targets
 MAKE_KERNEL   = $(MAKE) -C $(srctree) ARCH=$(ARCH) CC=$(CC) CROSS_COMPILE=$(CROSS_COMPILE)
-KERNEL_CONFIG = $(srctree)/.config
-KERNEL_IMAGE  = $(srctree)/$(IMAGE)
+KERNEL_CONFIG = $(objtree)/.config
+KERNEL_IMAGE  = $(objtree)/$(IMAGE)
 
 defconfig:
 	$(Q)$(MAKE_KERNEL) mrproper $(DEFCONFIG) prepare
 
 extconfig:
-	$(Q)$(srctree)/scripts/kconfig/merge_config.sh -O "$(srctree)" -m "$(KERNEL_CONFIG)" $(foreach c,$(EXTCONFIG),$(wildcard $(CURDIR)/configs/$c))
+	$(Q)$(srctree)/scripts/kconfig/merge_config.sh -O "$(objtree)" -m "$(KERNEL_CONFIG)" $(foreach c,$(EXTCONFIG),$(wildcard $(CURDIR)/configs/$c))
 	$(Q)$(MAKE_KERNEL) KCONFIG_ALLCONFIG="$(KERNEL_CONFIG)" allnoconfig
 
 kernel: initramfs
-- 
2.25.1