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| author |   Masahiro Yamada <masahiroy@kernel.org> | 2022-09-25 03:19:14 +0900 |
|---|---|---|
| committer | Masahiro Yamada <masahiroy@kernel.org> | 2022-10-02 18:04:05 +0900 |
| commit | 3216484550610470013b7ce1c9ed272da0a74589 (patch) | |
| tree | e24e7df02e90b7e798ae5aa67a5e4468142978c8 /Documentation/kbuild | |
| parent | kbuild: hide error checker logs for V=1 builds (diff) | |
| download | linux-dev-3216484550610470013b7ce1c9ed272da0a74589.tar.xz linux-dev-3216484550610470013b7ce1c9ed272da0a74589.zip | |
kbuild: use obj-y instead extra-y for objects placed at the head
The objects placed at the head of vmlinux need special treatments:
- arch/$(SRCARCH)/Makefile adds them to head-y in order to place
them before other archives in the linker command line.
- arch/$(SRCARCH)/kernel/Makefile adds them to extra-y instead of
obj-y to avoid them going into built-in.a.
This commit gets rid of the latter.
Create vmlinux.a to collect all the objects that are unconditionally
linked to vmlinux. The objects listed in head-y are moved to the head
of vmlinux.a by using 'ar m'.
With this, arch/$(SRCARCH)/kernel/Makefile can consistently use obj-y
for builtin objects.
There is no *.o that is directly linked to vmlinux. Drop unneeded code
in scripts/clang-tools/gen_compile_commands.py.
$(AR) mPi needs 'T' to workaround the llvm-ar bug. The fix was suggested
by Nathan Chancellor [1].
[1]: https://lore.kernel.org/llvm/YyjjT5gQ2hGMH0ni@dev-arch.thelio-3990X/
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Diffstat (limited to 'Documentation/kbuild')
| -rw-r--r-- | Documentation/kbuild/makefiles.rst | 18 |
1 files changed, 1 insertions, 17 deletions
diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst index ee7e3ea1fbe1..5a6a8426cc97 100644 --- a/Documentation/kbuild/makefiles.rst +++ b/Documentation/kbuild/makefiles.rst @@ -340,19 +340,7 @@ more details, with real examples. Examples are: - 1) head objects - - Some objects must be placed at the head of vmlinux. They are - directly linked to vmlinux without going through built-in.a - A typical use-case is an object that contains the entry point. - - arch/$(SRCARCH)/Makefile should specify such objects as head-y. - - Discussion: - Given that we can control the section order in the linker script, - why do we need head-y? - - 2) vmlinux linker script + 1) vmlinux linker script The linker script for vmlinux is located at arch/$(SRCARCH)/kernel/vmlinux.lds @@ -360,10 +348,6 @@ more details, with real examples. Example:: # arch/x86/kernel/Makefile - extra-y := head_$(BITS).o - extra-y += head$(BITS).o - extra-y += ebda.o - extra-y += platform-quirks.o extra-y += vmlinux.lds $(extra-y) should only contain targets needed for vmlinux. |