From 3832d1fd84b6220842d92513239005b2c116633b Mon Sep 17 00:00:00 2001 From: Robert Elliott Date: Sat, 27 Aug 2022 14:38:36 -0500 Subject: 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 | ^~~~~~~ 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 Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20220827193836.2582079-1-elliott@hpe.com Signed-off-by: Jonathan Corbet --- Documentation/kbuild/gcc-plugins.rst | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) 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 -- cgit v1.2.3-59-g8ed1b