|author||Geert Uytterhoeven <firstname.lastname@example.org>||2020-12-08 16:28:57 +0100|
|committer||Masahiro Yamada <email@example.com>||2020-12-21 13:57:08 +0900|
Documentation/kbuild: Document platform dependency practises
Document best practises for using architecture and platform dependencies. Signed-off-by: Geert Uytterhoeven <firstname.lastname@example.org> Signed-off-by: Masahiro Yamada <email@example.com>
Diffstat (limited to 'Documentation/kbuild')
1 files changed, 24 insertions, 0 deletions
diff --git a/Documentation/kbuild/kconfig-language.rst b/Documentation/kbuild/kconfig-language.rst
index 1b4875f04e13..226ae072da7d 100644
@@ -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