2018-02-09 1:19 GMT+09:00 Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>: > Moving compiler option tests to Kconfig means you need to re-run > Kconfig when you update your compiler. All CC_HAS_... symbols > and other symbols that depend on them must be re-calculated. > > It will be nice to detect the compiler update and automatically > invoke silentoldconfig. > > This can be done by adding one environment. With this, silentoldconfig > will add something like follows into include/config/auto.conf.cmd: > > ifneq "$(CC_VERSION_TEXT)" "gcc (Ubuntu 5.4.0-6ubuntu1~16.04.6) 5.4.0 20160609" > include/config/auto.conf: FORCE > endif > > CC_VERSION_TEXT contains the first line of "$(CC) --version". If this text > is changed, silentoldconfig will be invoked. > > Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> Currently, the updated compiler is detected only when building the kernel. External modules should be built by the same compiler as used for building the kernel. If a different compiler is used, different options will be specified by CONFIG_CC_HAS_... options from the .config Should this be checked? Or, is it just "Don't do it" thing? If desired, CONFIG_CC_VERSION_TEXT is cached in .config then it will be possible to compare it with $(shell $(CC) --version) when building external modules. > > Makefile | 2 ++ > init/Kconfig | 9 +++++++++ > 2 files changed, 11 insertions(+) > > diff --git a/Makefile b/Makefile > index 2ee49c9..9afd617 100644 > --- a/Makefile > +++ b/Makefile > @@ -441,6 +441,8 @@ export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE > export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL > export KBUILD_ARFLAGS > > +export CC_VERSION_TEXT := $(shell $(CC) --version | head -n 1) > + > # When compiling out-of-tree modules, put MODVERDIR in the module > # tree rather than in the kernel tree. The kernel tree might > # even be read-only. > diff --git a/init/Kconfig b/init/Kconfig > index e37f4b2..64f9dd2 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -16,6 +16,15 @@ config DEFCONFIG_LIST > default "$ARCH_DEFCONFIG" > default "arch/$ARCH/defconfig" > > +# CC_VERSION_TEXT is needed here to invoke Kconfig when compiler is updated > +config CC_VERSION_TEXT > + string > + option env="CC_VERSION_TEXT" > + help > + This is used to detect if the compiler is changed. If the version > + text does not match, silentoldconfig will be invoked because we need > + to re-compute compiler capabilities and symbols that depends on them. > + > config CONSTRUCTORS > bool > depends on !UML > -- > 2.7.4 > -- Best Regards Masahiro Yamada -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
