kbuild: add a flag to force absolute path for srctree (95fd3f87) · Commits · 戴 / test

In old days, Kbuild always used an absolute path for $(srctree). Since commit ("kbuild: Use relative path when building in the source tree"), $(srctree) is '.' when O= was not passed from the command line. Yet, using absolute paths is useful in some cases even without O=, for instance, to create a cscope file with absolute path tags. 'O=.' was known to work as a workaround to force Kbuild to use absolute paths even when you are building in the source tree. Since commit ("kbuild: allow Kbuild to start from any directory"), Kbuild is too clever to be tricked. Even if you pass 'O=.' Kbuild notices you are building in the source tree, then use '.' for $(srctree). So, 'make O=. cscope' is no help to create absolute path tags. We cannot force one or the other according to commit ("Revert "kbuild: specify absolute paths for cscope""). Both of relative path and absolute path have pros and cons. This commit adds a new flag KBUILD_ABS_SRCTREE to allow users to choose the absolute path for $(srctree). 'make KBUILD_ABS_SRCTREE=1 cscope' will work as a replacement of 'make O=. cscope'. Reported-by:

Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by:

Masahiro Yamada <yamada.masahiro@socionext.com>

Documentation/kbuild/kbuild.txt

+9 −0

Original line number	Diff line number	Diff line
		@@ -183,6 +183,15 @@ The output directory is often set using "O=..." on the commandline.

		The value can be overridden in which case the default value is ignored.

		KBUILD_ABS_SRCTREE
		--------------------------------------------------
		Kbuild uses a relative path to point to the tree when possible. For instance,
		when building in the source tree, the source tree path is '.'

		Setting this flag requests Kbuild to use absolute path to the source tree.
		There are some useful cases to do so, like when generating tag files with
		absolute path entries etc.

		KBUILD_SIGN_PIN
		--------------------------------------------------
		This variable allows a passphrase or PIN to be passed to the sign-file

Makefile

+4 −0

Original line number	Diff line number	Diff line
		@@ -244,6 +244,10 @@ else
		building_out_of_srctree := 1
		endif

		ifneq ($(KBUILD_ABS_SRCTREE),)
		srctree := $(abs_srctree)
		endif

		objtree := .
		VPATH := $(srctree)

scripts/tags.sh

+1 −2

Original line number	Diff line number	Diff line
		@@ -17,8 +17,7 @@ ignore="$(echo "$RCS_FIND_IGNORE" \| sed 's\|\\\|\|g' )"
		# tags and cscope files should also ignore MODVERSION *.mod.c files
		ignore="$ignore ( -name *.mod.c ) -prune -o"

		# Do not use full path if we do not use O=.. builds
		# Use make O=. {tags\|cscope}
		# Use make KBUILD_ABS_SRCTREE=1 {tags\|cscope}
		# to force full paths for a non-O= build
		if [ "${srctree}" = "." -o -z "${srctree}" ]; then
		tree=

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