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authorRobert Elliott <elliott@hpe.com>2022-08-27 14:38:36 -0500
committerJonathan Corbet <corbet@lwn.net>2022-09-27 13:21:44 -0600
commit3832d1fd84b6220842d92513239005b2c116633b (patch)
tree9945bae34f699f8f992fa17743d31cdb3c71e665 /Documentation/kbuild
parente2815b71cc48c988474dc2f2fc4725c5913f7155 (diff)
docs/core-api: expand Fedora instructions for GCC plugins
In Fedora 36, cross-compiling an allmodconfig configuration for other architectures on x86 fails with this problem: In file included from ../scripts/gcc-plugins/gcc-common.h:95, from ../scripts/gcc-plugins/latent_entropy_plugin.c:78: /usr/lib/gcc/aarch64-linux-gnu/12/plugin/include/builtins.h:23:10: fatal error: mpc.h: No such file or directory 23 | #include <mpc.h> | ^~~~~~~ compilation terminated. In that distro, that header file is available in the separate libmpc-devel package. Although future versions of Fedora might correctly mark that dependency, mention this additional package. To help detect such problems ahead of time, describe the gcc -print-file-name=plugin command that is used by scripts/gcc-plugins/Kconfig to detect plugins [1]. [1] https://lore.kernel.org/lkml/CAHk-=wjjiYjCp61gdAMpDOsUBU-A2hFFKJoVx5VAC7yV4K6WYg@xxxxxxxxxxxxxx/ Fixes: 43e96ef8b70c50f ("docs/core-api: Add Fedora instructions for GCC plugins"); Signed-off-by: Robert Elliott <elliott@hpe.com> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20220827193836.2582079-1-elliott@hpe.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'Documentation/kbuild')
-rw-r--r--Documentation/kbuild/gcc-plugins.rst19
1 files changed, 18 insertions, 1 deletions
diff --git a/Documentation/kbuild/gcc-plugins.rst b/Documentation/kbuild/gcc-plugins.rst
index 0ba76719f1b9..c578c6ba3eb6 100644
--- a/Documentation/kbuild/gcc-plugins.rst
+++ b/Documentation/kbuild/gcc-plugins.rst
@@ -90,7 +90,11 @@ e.g., on Ubuntu for gcc-10::
Or on Fedora::
- dnf install gcc-plugin-devel
+ dnf install gcc-plugin-devel libmpc-devel
+
+Or on Fedora when using cross-compilers that include plugins::
+
+ dnf install libmpc-devel
Enable the GCC plugin infrastructure and some plugin(s) you want to use
in the kernel config::
@@ -99,6 +103,19 @@ in the kernel config::
CONFIG_GCC_PLUGIN_LATENT_ENTROPY=y
...
+Run gcc (native or cross-compiler) to ensure plugin headers are detected::
+
+ gcc -print-file-name=plugin
+ CROSS_COMPILE=arm-linux-gnu- ${CROSS_COMPILE}gcc -print-file-name=plugin
+
+The word "plugin" means they are not detected::
+
+ plugin
+
+A full path means they are detected::
+
+ /usr/lib/gcc/x86_64-redhat-linux/12/plugin
+
To compile the minimum tool set including the plugin(s)::
make scripts