linux.git/Documentation/kbuild, branch v6.17

docs: kconfig: add alldefconfig to the all*configs

2025-07-26T06:31:29+00:00

Add "alldefconfig" to the explanation of the KCONFIG_ALLCONFIG
environment variable usage so that all targets that use KCONFIG_ALLCONFIG
are listed.

Signed-off-by: Randy Dunlap 
Signed-off-by: Masahiro Yamada

Merge tag 'kbuild-v6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2025-06-07T17:05:35+00:00

Pull Kbuild updates from Masahiro Yamada:

 - Add support for the EXPORT_SYMBOL_GPL_FOR_MODULES() macro, which
   exports a symbol only to specified modules

 - Improve ABI handling in gendwarfksyms

 - Forcibly link lib-y objects to vmlinux even if CONFIG_MODULES=n

 - Add checkers for redundant or missing  inclusion

 - Deprecate the extra-y syntax

 - Fix a genksyms bug when including enum constants from *.symref files

* tag 'kbuild-v6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (28 commits)
  genksyms: Fix enum consts from a reference affecting new values
  arch: use always-$(KBUILD_BUILTIN) for vmlinux.lds
  kbuild: set y instead of 1 to KBUILD_{BUILTIN,MODULES}
  efi/libstub: use 'targets' instead of extra-y in Makefile
  module: make __mod_device_table__* symbols static
  scripts/misc-check: check unnecessary #include  when W=1
  scripts/misc-check: check missing #include  when W=1
  scripts/misc-check: add double-quotes to satisfy shellcheck
  kbuild: move W=1 check for scripts/misc-check to top-level Makefile
  scripts/tags.sh: allow to use alternative ctags implementation
  kconfig: introduce menu type enum
  docs: symbol-namespaces: fix reST warning with literal block
  kbuild: link lib-y objects to vmlinux forcibly even when CONFIG_MODULES=n
  tinyconfig: enable CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
  docs/core-api/symbol-namespaces: drop table of contents and section numbering
  modpost: check forbidden MODULE_IMPORT_NS("module:") at compile time
  kbuild: move kbuild syntax processing to scripts/Makefile.build
  Makefile: remove dependency on archscripts for header installation
  Documentation/kbuild: Add new gendwarfksyms kABI rules
  Documentation/kbuild: Drop section numbers
  ...

kbuild: set y instead of 1 to KBUILD_{BUILTIN,MODULES}

2025-06-07T05:37:50+00:00

KBUILD_BUILTIN is set to 1 unless you are building only modules.

KBUILD_MODULES is set to 1 when you are building only modules
(a typical use case is "make modules").

It is more useful to set them to 'y' instead, so we can do
something like:

    always-$(KBUILD_BUILTIN) += vmlinux.lds

This works equivalently to:

    extra-y                  += vmlinux.lds

This allows us to deprecate extra-y. extra-y and always-y are quite
similar, and we do not need both.

Signed-off-by: Masahiro Yamada 
Reviewed-by: Nathan Chancellor 
Reviewed-by: Nicolas Schier

Merge tag 'gcc-minimum-version-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic

2025-05-31T15:16:52+00:00

Pull compiler version requirement update from Arnd Bergmann:
 "Require gcc-8 and binutils-2.30

  x86 already uses gcc-8 as the minimum version, this changes all other
  architectures to the same version. gcc-8 is used is Debian 10 and Red
  Hat Enterprise Linux 8, both of which are still supported, and
  binutils 2.30 is the oldest corresponding version on those.

  Ubuntu Pro 18.04 and SUSE Linux Enterprise Server 15 both use gcc-7 as
  the system compiler but additionally include toolchains that remain
  supported.

  With the new minimum toolchain versions, a number of workarounds for
  older versions can be dropped, in particular on x86_64 and arm64.
  Importantly, the updated compiler version allows removing two of the
  five remaining gcc plugins, as support for sancov and structeak
  features is already included in modern compiler versions.

  I tried collecting the known changes that are possible based on the
  new toolchain version, but expect that more cleanups will be possible.

  Since this touches multiple architectures, I merged the patches
  through the asm-generic tree."

* tag 'gcc-minimum-version-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
  Makefile.kcov: apply needed compiler option unconditionally in CFLAGS_KCOV
  Documentation: update binutils-2.30 version reference
  gcc-plugins: remove SANCOV gcc plugin
  Kbuild: remove structleak gcc plugin
  arm64: drop binutils version checks
  raid6: skip avx512 checks
  kbuild: require gcc-8 and binutils-2.30

Documentation/kbuild: Add new gendwarfksyms kABI rules

2025-05-25T09:12:23+00:00

Document the "byte_size" and "type_string" kABI stability rules.

Signed-off-by: Sami Tolvanen 
Signed-off-by: Masahiro Yamada

Documentation/kbuild: Drop section numbers

2025-05-25T09:12:23+00:00

Change the gendwarfksyms documentation to use proper chapter,
section, and subsection adornments instead of fragile section
numbers.

Suggested-by: Masahiro Yamada 
Signed-off-by: Sami Tolvanen 
Signed-off-by: Masahiro Yamada

Revert "kbuild: make all file references relative to source root"

2025-05-12T06:04:13+00:00

This reverts commit cacd22ce69585a91c386243cd662ada962431e63.

-ffile-prefix-map breaks the ability of debuggers to find the source
file corresponding to object files. As there is no simple or uniform
way to specify the source directory explicitly, this breaks developers
workflows.

Revert the unconditional usage of -ffile-prefix-map.

Reported-by: Matthieu Baerts 
Closes: https://lore.kernel.org/lkml/edc50aa7-0740-4942-8c15-96f12f2acc7e@kernel.org/
Reported-by: Ville Syrjälä 
Closes: https://lore.kernel.org/lkml/aBEttQH4kimHFScx@intel.com/
Fixes: cacd22ce6958 ("kbuild: make all file references relative to source root")
Signed-off-by: Thomas Weißschuh 
Signed-off-by: Masahiro Yamada

kbuild: require gcc-8 and binutils-2.30

2025-04-30T19:53:35+00:00

Commit a3e8fe814ad1 ("x86/build: Raise the minimum GCC version to 8.1")
raised the minimum compiler version as enforced by Kbuild to gcc-8.1
and clang-15 for x86.

This is actually the same gcc version that has been discussed as the
minimum for all architectures several times in the past, with little
objection. A previous concern was the kernel for SLE15-SP7 needing to
be built with gcc-7. As this ended up still using linux-6.4 and there
is no plan for an SP8, this is no longer a problem.

Change it for all architectures and adjust the documentation accordingly.
A few version checks can be removed in the process.  The binutils
version 2.30 is the lowest version used in combination with gcc-8 on
common distros, so use that as the corresponding minimum.

Link: https://lore.kernel.org/lkml/20240925150059.3955569-32-ardb+git@google.com/
Link: https://lore.kernel.org/lkml/871q7yxrgv.wl-tiwai@suse.de/
Acked-by: Mark Rutland 
Signed-off-by: Arnd Bergmann

kbuild: make all file references relative to source root

2025-03-22T14:50:58+00:00

-fmacro-prefix-map only affects __FILE__ and __BASE_FILE__.
Other references, for example in debug information, are not affected.
This makes handling of file references in the compiler outputs harder to
use and creates problems for reproducible builds.

Switch to -ffile-prefix map which affects all references.

Also drop the documentation section advising manual specification of
-fdebug-prefix-map for reproducible builds, as it is not necessary
anymore.

Suggested-by: Ben Hutchings 
Link: https://lore.kernel.org/lkml/c49cc967294f9a3a4a34f69b6a8727a6d3959ed8.camel@decadent.org.uk/
Signed-off-by: Thomas Weißschuh 
Signed-off-by: Masahiro Yamada

Documentation/kbuild: Fix indentation in modules.rst example

2025-03-16T15:29:51+00:00

Correct the indentation in an example within the `modules.rst` file
to improve readability.

Signed-off-by: Kefan Liu 
Signed-off-by: Masahiro Yamada