2018-08-07 3:33 GMT+09:00 Michal Kubecek [off-list ref]:

On Mon, Jul 30, 2018 at 05:02:42PM +0900, Masahiro Yamada wrote:

quoted

For exmaple 'make ARCH=arm config' will create the config suitable
only for ARM architecture.
Then, you need to do 'make ARCH=arm' to build the kernel.

If it is tedious to give 'ARCH=arm' to every make command,
you can do 'export ARCH=arm' in your shell.

Again, this is the behavior we have for a long time.

Actually, this no longer works reliably. For example, when I run

  ARCH=powerpc make oldconfig

with our ppc64le config on x86_64 system, I get different result than
when I run it on an actual ppc64le system (or when using a ppc64le cross
compiler on x86_64).

This is because you used different compilers.

Since .config started to mix user configuration and build environment
capabilities, maintaining distribution configs became real pain. And
it's getting progressively worse.

This is improvement requested by Linus Torvalds.

Prior to the change, the user configuration in the .config
did not reflect what you get.
Even if you enable CONFIG_FOO=y,
it might be silently disabled by $(call cc-option, ...) in Makefile
if the feature is not supported by the compiler.


By moving the compiler evaluation to the Kconfig phase,
the .config matches to what you get.

Michal Kubecek

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-- 
Best Regards
Masahiro Yamada