linux.git/Documentation/kbuild, branch v6.15 Linux kernel source tree Revert "kbuild: make all file references relative to source root" 2025-05-12T06:04:13+00:00 Thomas Weißschuh linux@weissschuh.net 2025-05-11T06:02:27+00:00 020d7f14489b8bc38c6bd4c5b3c25262e8b6de63 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 <matttbe@kernel.org> Closes: https://lore.kernel.org/lkml/edc50aa7-0740-4942-8c15-96f12f2acc7e@kernel.org/ Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com> 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 <linux@weissschuh.net> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> 
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 <matttbe@kernel.org>
Closes: https://lore.kernel.org/lkml/edc50aa7-0740-4942-8c15-96f12f2acc7e@kernel.org/
Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
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 <linux@weissschuh.net>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
kbuild: make all file references relative to source root 2025-03-22T14:50:58+00:00 Thomas Weißschuh linux@weissschuh.net 2025-03-15T13:20:14+00:00 cacd22ce69585a91c386243cd662ada962431e63 -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 <ben@decadent.org.uk> Link: https://lore.kernel.org/lkml/c49cc967294f9a3a4a34f69b6a8727a6d3959ed8.camel@decadent.org.uk/ Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> 
-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 <ben@decadent.org.uk>
Link: https://lore.kernel.org/lkml/c49cc967294f9a3a4a34f69b6a8727a6d3959ed8.camel@decadent.org.uk/
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Documentation/kbuild: Fix indentation in modules.rst example 2025-03-16T15:29:51+00:00 Kefan Liu liukefan24s@ict.ac.cn 2025-03-11T15:45:35+00:00 82e7a5997170f105dc5452f83f349e6e625e61f5 Correct the indentation in an example within the `modules.rst` file to improve readability. Signed-off-by: Kefan Liu <liukefan24s@ict.ac.cn> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> 
Correct the indentation in an example within the `modules.rst` file
to improve readability.

Signed-off-by: Kefan Liu <liukefan24s@ict.ac.cn>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
kbuild: add Kbuild bash completion 2025-03-15T12:22:52+00:00 Masahiro Yamada masahiroy@kernel.org 2025-03-06T15:56:22+00:00 eb47ee018173f144f10eb38a3f7bd9f17ec6329e Kernel build commands can sometimes be long, particularly when cross-compiling, making them tedious to type and prone to mistypes. This commit introduces bash completion support for common variables and targets in Kbuild. For installation instructions, please refer to the documentation in Documentation/kbuild/bash-completion.rst. The following examples demonstrate how this saves typing. [Example 1] a long command line for cross-compiling $ make A<TAB> -> completes 'A' to 'ARCH=' $ make ARCH=<TAB> -> displays all supported architectures $ make ARCH=arm64 CR<TAB> -> completes 'CR' to 'CROSS_COMPILE=' $ make ARCH=arm64 CROSS_COMPILE=<TAB> -> displays installed toolchains $ make ARCH=arm64 CROSS_COMPILE=aa<TAB> -> completes 'CROSS_COMPILE=aa' to 'CROSS_COMPILE=aarch64-linux-gnu-' $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- def<TAB> -> completes 'def' to 'defconfig' [Example 2] a single build target $ make f<TAB> -> completes 'f' to 'fs/' $ make fs/<TAB> -> displays objects and sub-directories in fs/ $ make fs/xf<TAB> -> completes 'fs/xf' to 'fs/xfs/' $ make fs/xfs/l<TAB> -> completes 'fs/xfs/l' to 'fs/xfs/libxfs/xfs_' $ make fs/xfs/libxfs/xfs_g<TAB> -> completes 'fs/xfs/libxfs/xfs_g' to 'fs/xfs/libxfs/xfs_group.o' This does not aim to provide a complete list of variables and targets, as there are too many. However, it covers variables and targets used in common scenarios, and I hope this is useful enough. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nicolas Schier <n.schier@avm.de> Tested-by: Nicolas Schier <n.schier@avm.de> 
Kernel build commands can sometimes be long, particularly when
cross-compiling, making them tedious to type and prone to mistypes.

This commit introduces bash completion support for common variables
and targets in Kbuild.

For installation instructions, please refer to the documentation in
Documentation/kbuild/bash-completion.rst.

The following examples demonstrate how this saves typing.

[Example 1] a long command line for cross-compiling

  $ make A<TAB>
   -> completes 'A' to 'ARCH='

  $ make ARCH=<TAB>
   -> displays all supported architectures

  $ make ARCH=arm64 CR<TAB>
   -> completes 'CR' to 'CROSS_COMPILE='

  $ make ARCH=arm64 CROSS_COMPILE=<TAB>
   -> displays installed toolchains

  $ make ARCH=arm64 CROSS_COMPILE=aa<TAB>
   -> completes 'CROSS_COMPILE=aa' to 'CROSS_COMPILE=aarch64-linux-gnu-'

  $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- def<TAB>
   -> completes 'def' to 'defconfig'

[Example 2] a single build target

  $ make f<TAB>
   -> completes 'f' to 'fs/'

  $ make fs/<TAB>
   -> displays objects and sub-directories in fs/

  $ make fs/xf<TAB>
   -> completes 'fs/xf' to 'fs/xfs/'

  $ make fs/xfs/l<TAB>
   -> completes 'fs/xfs/l' to 'fs/xfs/libxfs/xfs_'

  $ make fs/xfs/libxfs/xfs_g<TAB>
   -> completes 'fs/xfs/libxfs/xfs_g' to 'fs/xfs/libxfs/xfs_group.o'

This does not aim to provide a complete list of variables and targets,
as there are too many. However, it covers variables and targets used
in common scenarios, and I hope this is useful enough.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <n.schier@avm.de>
Tested-by: Nicolas Schier <n.schier@avm.de>
docs: kconfig: Mention IS_REACHABLE as way for optional dependency 2025-03-15T12:19:44+00:00 Krzysztof Kozlowski krzysztof.kozlowski@linaro.org 2025-02-17T11:31:53+00:00 700bd25bd4f47a0f4e02e0a25dde05f1a6b16eea Several drivers express optional Kconfig dependency with FOO || !FOO, but for many choices this is not suitable: lack of stubs for !FOO like in HWMON. Describe the second, less favorable way of optional dependency with IS_REACHABLE by moving the code from "imply" chapter to "Optional dependencies". Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> 
Several drivers express optional Kconfig dependency with FOO || !FOO,
but for many choices this is not suitable: lack of stubs for !FOO
like in HWMON.  Describe the second, less favorable way of optional
dependency with IS_REACHABLE by moving the code from "imply" chapter to
"Optional dependencies".

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
kbuild: rust: add rustc-min-version support function 2025-03-15T12:19:32+00:00 Miguel Ojeda ojeda@kernel.org 2025-02-10T16:42:45+00:00 ac954145e1ee3f72033161cbe4ac0b16b5354ae7 Introduce `rustc-min-version` support function that mimics `{gcc,clang}-min-version` ones, following commit 88b61e3bff93 ("Makefile.compiler: replace cc-ifversion with compiler-specific macros"). In addition, use it in the first use case we have in the kernel (which was done independently to minimize the changes needed for the fix). Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Reviewed-by: Fiona Behrens <me@Kloenk.dev> Reviewed-by: Nicolas Schier <n.schier@avm.de> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> 
Introduce `rustc-min-version` support function that mimics
`{gcc,clang}-min-version` ones, following commit 88b61e3bff93
("Makefile.compiler: replace cc-ifversion with compiler-specific macros").

In addition, use it in the first use case we have in the kernel (which
was done independently to minimize the changes needed for the fix).

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: Fiona Behrens <me@Kloenk.dev>
Reviewed-by: Nicolas Schier <n.schier@avm.de>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
kbuild: remove EXTRA_*FLAGS support 2025-03-15T12:16:21+00:00 Masahiro Yamada masahiroy@kernel.org 2025-02-05T16:39:38+00:00 e966ad0edd0056c7491b8f23992c11734ab61ddf Commit f77bf01425b1 ("kbuild: introduce ccflags-y, asflags-y and ldflags-y") deprecated these in 2007. The migration should have been completed by now. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Kees Cook <kees@kernel.org> Reviewed-by: Nathan Chancellor <nathan@kernel.org> 
Commit f77bf01425b1 ("kbuild: introduce ccflags-y, asflags-y and
ldflags-y") deprecated these in 2007. The migration should have been
completed by now.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Merge tag 'kbuild-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild 2025-01-31T20:07:07+00:00 Linus Torvalds torvalds@linux-foundation.org 2025-01-31T20:07:07+00:00 fd8c09ad0d87783b9b6a27900d66293be45b7bad Pull Kbuild updates from Masahiro Yamada: - Support multiple hook locations for maint scripts of Debian package - Remove 'cpio' from the build tool requirement - Introduce gendwarfksyms tool, which computes CRCs for export symbols based on the DWARF information - Support CONFIG_MODVERSIONS for Rust - Resolve all conflicts in the genksyms parser - Fix several syntax errors in genksyms * tag 'kbuild-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (64 commits) kbuild: fix Clang LTO with CONFIG_OBJTOOL=n kbuild: Strip runtime const RELA sections correctly kconfig: fix memory leak in sym_warn_unmet_dep() kconfig: fix file name in warnings when loading KCONFIG_DEFCONFIG_LIST genksyms: fix syntax error for attribute before init-declarator genksyms: fix syntax error for builtin (u)int*x*_t types genksyms: fix syntax error for attribute after 'union' genksyms: fix syntax error for attribute after 'struct' genksyms: fix syntax error for attribute after abstact_declarator genksyms: fix syntax error for attribute before nested_declarator genksyms: fix syntax error for attribute before abstract_declarator genksyms: decouple ATTRIBUTE_PHRASE from type-qualifier genksyms: record attributes consistently for init-declarator genksyms: restrict direct-declarator to take one parameter-type-list genksyms: restrict direct-abstract-declarator to take one parameter-type-list genksyms: remove Makefile hack genksyms: fix last 3 shift/reduce conflicts genksyms: fix 6 shift/reduce conflicts and 5 reduce/reduce conflicts genksyms: reduce type_qualifier directly to decl_specifier genksyms: rename cvar_qualifier to type_qualifier ... 
Pull Kbuild updates from Masahiro Yamada:

 - Support multiple hook locations for maint scripts of Debian package

 - Remove 'cpio' from the build tool requirement

 - Introduce gendwarfksyms tool, which computes CRCs for export symbols
   based on the DWARF information

 - Support CONFIG_MODVERSIONS for Rust

 - Resolve all conflicts in the genksyms parser

 - Fix several syntax errors in genksyms

* tag 'kbuild-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (64 commits)
  kbuild: fix Clang LTO with CONFIG_OBJTOOL=n
  kbuild: Strip runtime const RELA sections correctly
  kconfig: fix memory leak in sym_warn_unmet_dep()
  kconfig: fix file name in warnings when loading KCONFIG_DEFCONFIG_LIST
  genksyms: fix syntax error for attribute before init-declarator
  genksyms: fix syntax error for builtin (u)int*x*_t types
  genksyms: fix syntax error for attribute after 'union'
  genksyms: fix syntax error for attribute after 'struct'
  genksyms: fix syntax error for attribute after abstact_declarator
  genksyms: fix syntax error for attribute before nested_declarator
  genksyms: fix syntax error for attribute before abstract_declarator
  genksyms: decouple ATTRIBUTE_PHRASE from type-qualifier
  genksyms: record attributes consistently for init-declarator
  genksyms: restrict direct-declarator to take one parameter-type-list
  genksyms: restrict direct-abstract-declarator to take one parameter-type-list
  genksyms: remove Makefile hack
  genksyms: fix last 3 shift/reduce conflicts
  genksyms: fix 6 shift/reduce conflicts and 5 reduce/reduce conflicts
  genksyms: reduce type_qualifier directly to decl_specifier
  genksyms: rename cvar_qualifier to type_qualifier
  ...
kbuild: rust: add PROCMACROLDFLAGS 2025-01-15T08:53:54+00:00 HONG Yifan elsk@google.com 2024-11-12T18:44:55+00:00 ceff0757f5dafb5be5205988171809c877b1d3e3 These are flags to be passed when linking proc macros for the Rust toolchain. If unset, it defaults to $(KBUILD_HOSTLDFLAGS). This is needed because the list of flags to link hostprogs is not necessarily the same as the list of flags used to link libmacros.so. When we build proc macros, we need the latter, not the former (e.g. when using a Rust compiler binary linked to a different C library than host programs). To distinguish between the two, introduce this new variable to stand out from KBUILD_HOSTLDFLAGS used to link other host progs. Signed-off-by: HONG Yifan <elsk@google.com> Link: https://lore.kernel.org/r/20241017210430.2401398-2-elsk@google.com [ v3: - `export`ed the variable. Otherwise it would not be visible in `rust/Makefile`. - Removed "additional" from the documentation and commit message, since this actually replaces the other flags, unlike other cases. - Added example of use case to documentation and commit message. Thanks Alice for the details on what Google needs! - Instead of `HOSTLDFLAGS`, used `KBUILD_HOSTLDFLAGS` as the fallback to preserve the previous behavior as much as possible, as discussed with Alice/Yifan. Thus moved the variable down too (currently we do not modify `KBUILD_HOSTLDFLAGS` elsewhere) and avoided mentioning `HOSTLDFLAGS` directly in the documentation. - Fixed documentation header formatting. - Reworded slightly. - Miguel ] Tested-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: HONG Yifan <elsk@google.com> Acked-by: Masahiro Yamada <masahiroy@kernel.org> Link: https://lore.kernel.org/r/20241112184455.855133-1-ojeda@kernel.org Signed-off-by: Miguel Ojeda <ojeda@kernel.org> 
These are flags to be passed when linking proc macros for the Rust
toolchain. If unset, it defaults to $(KBUILD_HOSTLDFLAGS).

This is needed because the list of flags to link hostprogs is not
necessarily the same as the list of flags used to link libmacros.so.
When we build proc macros, we need the latter, not the former (e.g. when
using a Rust compiler binary linked to a different C library than host
programs).

To distinguish between the two, introduce this new variable to stand
out from KBUILD_HOSTLDFLAGS used to link other host progs.

Signed-off-by: HONG Yifan <elsk@google.com>
Link: https://lore.kernel.org/r/20241017210430.2401398-2-elsk@google.com
[ v3:

  - `export`ed the variable. Otherwise it would not be visible in
    `rust/Makefile`.

  - Removed "additional" from the documentation and commit message,
    since this actually replaces the other flags, unlike other cases.

  - Added example of use case to documentation and commit message.
    Thanks Alice for the details on what Google needs!

  - Instead of `HOSTLDFLAGS`, used `KBUILD_HOSTLDFLAGS` as the fallback
    to preserve the previous behavior as much as possible, as discussed
    with Alice/Yifan. Thus moved the variable down too (currently we
    do not modify `KBUILD_HOSTLDFLAGS` elsewhere) and avoided
    mentioning `HOSTLDFLAGS` directly in the documentation.

  - Fixed documentation header formatting.

  - Reworded slightly.

         - Miguel ]
Tested-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: HONG Yifan <elsk@google.com>
Acked-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20241112184455.855133-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Documentation/kbuild: Document storage of symbol information 2025-01-10T17:36:36+00:00 Matthew Maurer mmaurer@google.com 2025-01-03T17:37:04+00:00 272f8a6d625a0cf7fba9c5af5202edc84dee326c Document where exported and imported symbols are kept, format options, and limitations. Signed-off-by: Matthew Maurer <mmaurer@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> 
Document where exported and imported symbols are kept, format options,
and limitations.

Signed-off-by: Matthew Maurer <mmaurer@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>