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| author | Mark Brown <broonie@kernel.org> | 2026-05-29 18:08:24 +0100 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2026-05-29 18:08:24 +0100 |
| commit | 941509f96942e695a03a74ef27c383e4dcaa02d9 (patch) | |
| tree | e8112f512d9ba26b81bd169e316ce055c331639a /Documentation | |
| parent | abe9aea29db876486fe215636f1070487d00a483 (diff) | |
| parent | 2c31897a17e55a6da529b4e797e98c6febc60fd2 (diff) | |
| download | linux-next-history-941509f96942e695a03a74ef27c383e4dcaa02d9.tar.gz | |
Merge branch 'kbuild-for-next' of https://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux.git
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/kbuild/makefiles.rst | 41 |
1 files changed, 33 insertions, 8 deletions
diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst index 24a4708d26e8e..7521cae7d56f1 100644 --- a/Documentation/kbuild/makefiles.rst +++ b/Documentation/kbuild/makefiles.rst @@ -1285,8 +1285,39 @@ Example:: In this example, the file target maketools will be processed before descending down in the subdirectories. -See also chapter XXX-TODO that describes how kbuild supports -generating offset header files. +Generating offset header files +------------------------------ + +The ``include/generated/asm-offsets.h`` header exposes C structure +member offsets and other compile-time constants to assembly code. It +is generated from ``arch/$(SRCARCH)/kernel/asm-offsets.c``. + +The source file uses ``DEFINE()``, ``OFFSET()``, ``BLANK()`` and +``COMMENT()`` from ``<linux/kbuild.h>``. These emit marker strings +through inline asm that Kbuild extracts from the compiled assembly +output. + +Example:: + + #include <linux/kbuild.h> + #include <linux/sched.h> + + int main(void) + { + OFFSET(TSK_ACTIVE_MM, task_struct, active_mm); + DEFINE(THREAD_SIZE, THREAD_SIZE); + BLANK(); + return 0; + } + +The rules are defined in the top-level ``Kbuild`` and +``scripts/Makefile.lib``. The header is built during Kbuild's +``prepare`` phase, after ``archprepare`` and before descending into +subdirectories. + +The same mechanism generates ``include/generated/bounds.h`` from +``kernel/bounds.c`` and ``include/generated/rq-offsets.h`` from +``kernel/sched/rq-offsets.c``. List directories to visit when descending ----------------------------------------- @@ -1690,9 +1721,3 @@ Credits - Updates by Kai Germaschewski <kai@tp1.ruhr-uni-bochum.de> - Updates by Sam Ravnborg <sam@ravnborg.org> - Language QA by Jan Engelhardt <jengelh@gmx.de> - -TODO -==== - -- Generating offset header files. -- Add more variables to chapters 7 or 9? |