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authorMasahiro Yamada <masahiroy@kernel.org>2023-12-16 01:06:37 +0900
committerMasahiro Yamada <masahiroy@kernel.org>2023-12-29 22:25:21 +0900
commit7beba04eb305393e3f8386390f25b4a9475f27f2 (patch)
tree8e35c7f8a4676e4468ebb7587e660ab0ddcadc61 /Makefile
parent8c88bc5b489e785c7ead94ce6fc3adb7f76e8715 (diff)
downloadlwn-7beba04eb305393e3f8386390f25b4a9475f27f2.tar.gz
lwn-7beba04eb305393e3f8386390f25b4a9475f27f2.zip
kbuild: resolve symlinks for O= properly
Currently, Kbuild follows the logical chain of directories for the O= option, just like 'cd' (or 'realpath --logical') does. Example: $ mkdir -p /tmp/a /tmp/x/y $ ln -s /tmp/x/y /tmp/a/b $ realpath /tmp/a/b/.. /tmp/x $ realpath --logical /tmp/a/b/.. /tmp/a $ make O=/tmp/a/b/.. defconfig make[1]: Entering directory '/tmp/a' [snip] make[1]: Leaving directory '/tmp/a' 'make O=/tmp/a/b/.. defconfig' creates the kernel configuration in /tmp/a instead of /tmp/x despite /tmp/a/b/.. resolves to /tmp/x. This is because Kbuild internally uses the 'cd ... && pwd' for the path resolution, but this behavior is not predictable for users. Additionally, it is not consistent with how the Kbuild handles the M= option or GNU Make works with 'make -C /tmp/a/b/..'. Using the physical directory structure for the O= option seems more reasonable. The comment says "expand a shell special character '~'", but it has already been expanded to the home directory in the command line. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nicolas Schier <n.schier@avm.de>
Diffstat (limited to 'Makefile')
-rw-r--r--Makefile11
1 files changed, 4 insertions, 7 deletions
diff --git a/Makefile b/Makefile
index 5a11804af640..6204a3803a90 100644
--- a/Makefile
+++ b/Makefile
@@ -190,14 +190,11 @@ ifeq ("$(origin O)", "command line")
endif
ifneq ($(KBUILD_OUTPUT),)
-# Make's built-in functions such as $(abspath ...), $(realpath ...) cannot
-# expand a shell special character '~'. We use a somewhat tedious way here.
-abs_objtree := $(shell mkdir -p $(KBUILD_OUTPUT) && cd $(KBUILD_OUTPUT) && pwd)
-$(if $(abs_objtree),, \
- $(error failed to create output directory "$(KBUILD_OUTPUT)"))
-
+# $(realpath ...) gets empty if the path does not exist. Run 'mkdir -p' first.
+$(shell mkdir -p "$(KBUILD_OUTPUT)")
# $(realpath ...) resolves symlinks
-abs_objtree := $(realpath $(abs_objtree))
+abs_objtree := $(realpath $(KBUILD_OUTPUT))
+$(if $(abs_objtree),,$(error failed to create output directory "$(KBUILD_OUTPUT)"))
endif # ifneq ($(KBUILD_OUTPUT),)
ifneq ($(words $(subst :, ,$(abs_srctree))), 1)