Document best practises for using architecture and platform dependencies. Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx> --- Documentation/kbuild/kconfig-language.rst | 24 +++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/Documentation/kbuild/kconfig-language.rst b/Documentation/kbuild/kconfig-language.rst index 2b746332d8aa6bce..87e9bbe14a21ce83 100644 --- a/Documentation/kbuild/kconfig-language.rst +++ b/Documentation/kbuild/kconfig-language.rst @@ -564,6 +564,30 @@ common system, and detect bugs that way. Note that compile-tested code should avoid crashing when run on a system where the dependency is not met. +Architecture and platform dependencies +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Due to the presence of stubs, most drivers can now be compiled on most +architectures. However, this does not mean it makes sense to have all drivers +available everywhere, as the actual hardware may only exist on specific +architectures and platforms. This is especially true for on-SoC IP cores, +which may be limited to a specific vendor or SoC family. + +To prevent asking the user about drivers that cannot be used on the system(s) +the user is compiling a kernel for, and if it makes sense, config symbols +controlling the compilation of a driver should contain proper dependencies, +limiting the visibility of the symbol to (a superset of) the platform(s) the +driver can be used on. The dependency can be an architecture (e.g. ARM) or +platform (e.g. ARCH_OMAP4) dependency. This makes life simpler not only for +distro config owners, but also for every single developer or user who +configures a kernel. + +Such a dependency can be relaxed by combining it with the compile-testing rule +above, leading to: + + config FOO + bool "Support for foo hardware" + depends on ARCH_FOO_VENDOR || COMPILE_TEST + Kconfig recursive dependency limitations ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -- 2.25.1
