From: Geert Uytterhoeven <geert+renesas@glider.be>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Masahiro Yamada <masahiroy@kernel.org>,
Michal Marek <michal.lkml@markovi.net>,
Jonathan Corbet <corbet@lwn.net>, Arnd Bergmann <arnd@arndb.de>
Cc: linux-kbuild@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Geert Uytterhoeven <geert+renesas@glider.be>
Subject: [PATCH 2/2] Documentation/kbuild: Document platform dependency practises
Date: Tue, 8 Dec 2020 16:28:57 +0100 [thread overview]
Message-ID: <20201208152857.2162093-3-geert+renesas@glider.be> (raw)
In-Reply-To: <20201208152857.2162093-1-geert+renesas@glider.be>
Document best practises for using architecture and platform dependencies.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
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
next prev parent reply other threads:[~2020-12-08 15:30 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-08 15:28 [PATCH 0/2] Documentation/kbuild: Document COMPILE_TEST and platform dependencies Geert Uytterhoeven
2020-12-08 15:28 ` [PATCH 1/2] Documentation/kbuild: Document COMPILE_TEST dependencies Geert Uytterhoeven
2020-12-08 15:44 ` Arnd Bergmann
2020-12-19 16:10 ` Masahiro Yamada
2020-12-08 15:28 ` Geert Uytterhoeven [this message]
2020-12-08 15:43 ` [PATCH 2/2] Documentation/kbuild: Document platform dependency practises Arnd Bergmann
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