path: root/Documentation/kbuild
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authorMasahiro Yamada <>2019-12-19 17:33:29 +0900
committerMasahiro Yamada <>2020-01-07 02:18:39 +0900
commit8b41fc4454e36fbfdbb23f940d023d4dece2de29 (patch)
tree2ee0b61a2b149f4a9cb291d8721ce0b324803e8f /Documentation/kbuild
parent1664a377908ed6096680e9d7cfd28facef2194f2 (diff)
kbuild: create modules.builtin without Makefile.modbuiltin or tristate.conf
Commit bc081dd6e9f6 ("kbuild: generate modules.builtin") added infrastructure to generate modules.builtin, the list of all builtin modules. Basically, it works like this: - Kconfig generates include/config/tristate.conf, the list of tristate CONFIG options with a value in a capital letter. - scripts/Makefile.modbuiltin makes Kbuild descend into directories to collect the information of builtin modules. I am not a big fan of it because Kbuild ends up with traversing the source tree twice. I am not sure how perfectly it should work, but this approach cannot avoid false positives; even if the relevant CONFIG option is tristate, some Makefiles forces obj-m to obj-y. Some examples are: arch/powerpc/platforms/powermac/Makefile: obj-$(CONFIG_NVRAM:m=y) += nvram.o net/ipv6/Makefile: obj-$(subst m,y,$(CONFIG_IPV6)) += inet6_hashtables.o net/netlabel/Makefile: obj-$(subst m,y,$(CONFIG_IPV6)) += netlabel_calipso.o Nobody has complained about (or noticed) it, so it is probably fine to have false positives in modules.builtin. This commit simplifies the implementation. Let's exploit the fact that every module has MODULE_LICENSE(). (modpost shows a warning if MODULE_LICENSE is missing. If so, 0-day bot would already have blocked such a module.) I added MODULE_FILE to <linux/module.h>. When the code is being compiled as builtin, it will be filled with the file path of the module, and collected into Then, scripts/ extracts the list of builtin modules out of it. This new approach fixes the false-positives above, but adds another type of false-positives; non-modular code may have MODULE_LICENSE() by mistake. This is not a big deal, it is just the code is always orphan. We can clean it up if we like. You can see cleanup examples by: $ git log --grep='make.* explicitly non-modular' To sum up, this commits deletes lots of code, but still produces almost equivalent results. Please note it does not increase the vmlinux size at all. As you can see in include/asm-generic/, the .modinfo section is discarded in the link stage. Signed-off-by: Masahiro Yamada <>
Diffstat (limited to 'Documentation/kbuild')
1 files changed, 0 insertions, 5 deletions
diff --git a/Documentation/kbuild/kconfig.rst b/Documentation/kbuild/kconfig.rst
index a9a855f894b3..dce6801d66c9 100644
--- a/Documentation/kbuild/kconfig.rst
+++ b/Documentation/kbuild/kconfig.rst
@@ -154,11 +154,6 @@ KCONFIG_AUTOCONFIG
This environment variable can be set to specify the path & name of the
"auto.conf" file. Its default value is "include/config/auto.conf".
-This environment variable can be set to specify the path & name of the
-"tristate.conf" file. Its default value is "include/config/tristate.conf".
This environment variable can be set to specify the path & name of the