On Thu, Aug 26, 2021 at 12:42 AM Boris Kolpackov boris@codesynthesis.com wrote:
Masahiro Yamada masahiroy@kernel.org writes:
Kconfig (syncconfig) generates include/generated/autoconf.h to make CONFIG options available to the pre-processor.
The macros are suffixed with '_MODULE' for symbols with the value 'm'.
Here is a conflict; CONFIG_FOO=m results in '#define CONFIG_FOO_MODULE 1', but CONFIG_FOO_MODULE=y also results in the same define.
fixdep always assumes CONFIG_FOO_MODULE comes from CONFIG_FOO=m, so the dependency is not properly tracked for symbols that end with '_MODULE'.
It seem to me the problem is in autoconf.h/fixdep, not in the Kconfig language.
Partly a Kconfig problem since autoconf.h is generated by Kconfig.
So, what is your suggestion for doing this correctly? (of course without breaking the compatibility because this is how the kernel is configured/built for more than 20 years)
This commit makes Kconfig error out if it finds a symbol suffixed with '_MODULE'.
I know you don't care, but I will voice my objection, for the record: Kconfig is used by projects other than the Linux kernel and some of them do not use the autoconf.h functionality. For such projects this restriction seems arbitrary and potentially backwards-incompatible.
I am not sure what your worry is, but this check resides in "if (modules_sym)" conditional, so projects using Kconfig but not module functionality (e.g. buildroot) will not be affected.