summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorGeert Uytterhoeven <geert+renesas@glider.be>2020-12-08 16:28:57 +0100
committerMasahiro Yamada <masahiroy@kernel.org>2020-12-21 13:57:08 +0900
commit18084e435ff6e47197542db6bab98bafaa4c7b68 (patch)
tree1744ea0a5f727b2940bc82dc8814ce7eb12186c0
parentc613583b6a87434123fc6714acbec6522859185e (diff)
Documentation/kbuild: Document platform dependency practises
Document best practises for using architecture and platform dependencies. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
-rw-r--r--Documentation/kbuild/kconfig-language.rst24
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
--- 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
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~