Getting system config option and using it as a compiler '-D' option

[voidtrance]

I want to add a -D<CACHLINE SIZE> to the compiler options used by Meson. The value of <CACHELINE_SIZE> will come from getconf LEVEL1_DCACHE_LINESIZE. However, I want that to be automatic as part of the build instead of as part of the meson configure.

Is there a way to do that?

[bonzini]

You can use run_command to execute getconf. Though the cache line size is a run-time parameter, so the code may not be optimal on other processors than the one you compiled on.

[voidtrance]

The run_command will get the value but how do I set the compiler option?

[bonzini]

With add_project_arguments or the c_args argument, just like any other compiler option.