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@xxxxxxx>
---
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
--
2.37.1
