| Message ID | 1518106752-29228-6-git-send-email-yamada.masahiro@socionext.com |
|---|---|
| State | New |
| Headers | show |
| Series | Kconfig: add new special property shell= to test compiler options in Kconfig | expand |
2018-02-09 1:19 GMT+09:00 Masahiro Yamada <yamada.masahiro@socionext.com>: > 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@socionext.com> 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
On Thu, Feb 8, 2018 at 9:19 AM, Masahiro Yamada <yamada.masahiro@socionext.com> wrote: > > Should this be checked? > Or, is it just "Don't do it" thing? I think it's probably a "Don't do it". In fact, maybe we should just make it very explicit that you need to re-run "make *config" by hand if you have updated your compiler. So instead of your "run silentoldconfig" if the compiler version has changed, just literally error out and say "compiler has changed, re-run configuration". That way there are no subtle silent failures where you might end up - by mistake - building just modules with a new compiler and different options. Because people would be *aware* of the re-configuration. Anyway, I suspect this is a tiny detail that we don't have to set in stone right now. Maybe worry about it more when/if it actually becomes something that people notice? Linus
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/$ARCH/defconfig" +# CC_VERSION_TEXT is needed here to invoke Kconfig when compiler is updated +config CC_VERSION_TEXT + string + option env="CC_VERSION_TEXT" + help + This is used to detect if the compiler is changed. If the version + text does not match, silentoldconfig will be invoked because we need + to re-compute compiler capabilities and symbols that depends on them. + config CONSTRUCTORS bool depends on !UML
Moving compiler option tests to Kconfig means you need to re-run Kconfig when you update your compiler. All CC_HAS_... symbols and other symbols that depend on them must be re-calculated. It will be nice to detect the compiler update and automatically invoke silentoldconfig. This can be done by adding one environment. With this, silentoldconfig will add something like follows into include/config/auto.conf.cmd: ifneq "$(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@socionext.com> --- Makefile | 2 ++ init/Kconfig | 9 +++++++++ 2 files changed, 11 insertions(+) -- 2.7.4