kbuild: use $(src) instead of $(srctree)/$(src) for source directory
Kbuild conventionally uses $(obj)/ for generated files, and $(src)/ for
checked-in source files. It is merely a convention without any functional
difference. In fact, $(obj) and $(src) are exactly the same, as defined
in scripts/Makefile.build:
src := $(obj)
When the kernel is built in a separate output directory, $(src) does
not accurately reflect the source directory location. While Kbuild
resolves this discrepancy by specifying VPATH=$(srctree) to search for
source files, it does not cover all cases. For example, when adding a
header search path for local headers, -I$(srctree)/$(src) is typically
passed to the compiler.
This introduces inconsistency between upstream and downstream Makefiles
because $(src) is used instead of $(srctree)/$(src) for the latter.
To address this inconsistency, this commit changes the semantics of
$(src) so that it always points to the directory in the source tree.
Going forward, the variables used in Makefiles will have the following
meanings:
$(obj) - directory in the object tree
$(src) - directory in the source tree (changed by this commit)
$(objtree) - the top of the kernel object tree
$(srctree) - the top of the kernel source tree
Consequently, $(srctree)/$(src) in upstream Makefiles need to be replaced
with $(src).
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
diff --git a/scripts/dtc/Makefile b/scripts/dtc/Makefile
index 4d32b94..a186570 100644
--- a/scripts/dtc/Makefile
+++ b/scripts/dtc/Makefile
@@ -16,12 +16,12 @@
fdtoverlay-objs := $(libfdt) fdtoverlay.o util.o
# Source files need to get at the userspace version of libfdt_env.h to compile
-HOST_EXTRACFLAGS += -I $(srctree)/$(src)/libfdt
+HOST_EXTRACFLAGS += -I $(src)/libfdt
HOST_EXTRACFLAGS += -DNO_YAML
# Generated files need one more search path to include headers in source tree
-HOSTCFLAGS_dtc-lexer.lex.o := -I $(srctree)/$(src)
-HOSTCFLAGS_dtc-parser.tab.o := -I $(srctree)/$(src)
+HOSTCFLAGS_dtc-lexer.lex.o := -I $(src)
+HOSTCFLAGS_dtc-parser.tab.o := -I $(src)
# dependencies on generated files need to be listed explicitly
$(obj)/dtc-lexer.lex.o: $(obj)/dtc-parser.tab.h
