linux/Documentation/kbuild
Masahiro Yamada b1992c3772 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>
2024-05-10 04:34:52 +09:00
..
gcc-plugins.rst docs/core-api: expand Fedora instructions for GCC plugins 2022-09-27 13:21:44 -06:00
headers_install.rst Kbuild updates for v5.3 2019-07-12 16:03:16 -07:00
index.rst Kbuild updates for v5.7 2020-03-31 16:03:39 -07:00
issues.rst docs: kbuild: fix build with pdf and fix some minor issues 2019-07-15 11:03:04 -03:00
kbuild.rst docs: kbuild: add INSTALL_DTBS_PATH 2023-10-18 17:16:09 +09:00
kconfig-language.rst kconfig: remove 'optional' property support 2024-05-02 19:48:26 +09:00
kconfig-macro-language.rst kconfig: doc: fix $(fileno) to $(filename) 2020-12-21 16:01:44 +09:00
Kconfig.recursion-issue-01 docs: kconfig: Fix grammar and formatting 2024-02-15 06:55:47 +09:00
Kconfig.recursion-issue-02 docs: use the lore redirector everywhere 2021-10-12 13:58:19 -06:00
kconfig.rst docs: kbuild/kconfig: reformat/cleanup 2024-02-19 18:20:39 +09:00
Kconfig.select-break kbuild: document recursive dependency limitation / resolution 2015-10-08 15:36:16 +02:00
llvm.rst Documentation/llvm: Note s390 LLVM=1 support with LLVM 18.1.0 and newer 2024-03-31 21:09:50 +09:00
makefiles.rst kbuild: use $(src) instead of $(srctree)/$(src) for source directory 2024-05-10 04:34:52 +09:00
modules.rst kbuild: doc: replace arch/$(ARCH)/ with arch/$(SRCARCH)/ 2020-12-21 13:56:58 +09:00
reproducible-builds.rst Documentation: kbuild: Add description of git for reproducible builds 2022-10-28 00:16:29 +09:00