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| author |   Masahiro Yamada <masahiroy@kernel.org> | 2022-09-25 03:19:15 +0900 |
|---|---|---|
| committer | Masahiro Yamada <masahiroy@kernel.org> | 2022-10-02 18:06:03 +0900 |
| commit | ce697ccee1a8661da4e23fbe5f3d45d8d6922c20 (patch) | |
| tree | 3e4a66982f38b33d4c17b13a04161eb764bf6220 /Documentation/kbuild | |
| parent | kbuild: use obj-y instead extra-y for objects placed at the head (diff) | |
| download | linux-dev-ce697ccee1a8661da4e23fbe5f3d45d8d6922c20.tar.xz linux-dev-ce697ccee1a8661da4e23fbe5f3d45d8d6922c20.zip | |
kbuild: remove head-y syntax
Kbuild puts the objects listed in head-y at the head of vmlinux.
Conventionally, we do this for head*.S, which contains the kernel entry
point.
A counter approach is to control the section order by the linker script.
Actually, the code marked as __HEAD goes into the ".head.text" section,
which is placed before the normal ".text" section.
I do not know if both of them are needed. From the build system
perspective, head-y is not mandatory. If you can achieve the proper code
placement by the linker script only, it would be cleaner.
I collected the current head-y objects into head-object-list.txt. It is
a whitelist. My hope is it will be reduced in the long run.
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 | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst index 5a6a8426cc97..60134ddf3db1 100644 --- a/Documentation/kbuild/makefiles.rst +++ b/Documentation/kbuild/makefiles.rst @@ -1070,8 +1070,7 @@ When kbuild executes, the following steps are followed (roughly): - The values of the above variables are expanded in arch/$(SRCARCH)/Makefile. 5) All object files are then linked and the resulting file vmlinux is located at the root of the obj tree. - The very first objects linked are listed in head-y, assigned by - arch/$(SRCARCH)/Makefile. + The very first objects linked are listed in scripts/head-object-list.txt. 6) Finally, the architecture-specific part does any required post processing and builds the final bootimage. - This includes building boot records @@ -1219,6 +1218,9 @@ When kbuild executes, the following steps are followed (roughly): All object files for vmlinux. They are linked to vmlinux in the same order as listed in KBUILD_VMLINUX_OBJS. + The objects listed in scripts/head-object-list.txt are exceptions; + they are placed before the other objects. + KBUILD_VMLINUX_LIBS All .a "lib" files for vmlinux. KBUILD_VMLINUX_OBJS and @@ -1262,8 +1264,7 @@ When kbuild executes, the following steps are followed (roughly): machinery is all architecture-independent. - head-y, core-y, libs-y, drivers-y - $(head-y) lists objects to be linked first in vmlinux. + core-y, libs-y, drivers-y $(libs-y) lists directories where a lib.a archive can be located. |