On 11/22/20 8:54 PM, Masahiro Yamada wrote: > There is no explanation about subdir-y. > > Let's document it. > > Signed-off-by: Masahiro Yamada <masahi...@kernel.org> > --- > > Documentation/kbuild/makefiles.rst | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/Documentation/kbuild/makefiles.rst > b/Documentation/kbuild/makefiles.rst > index 159e470f2616..6332b9ca7942 100644 > --- a/Documentation/kbuild/makefiles.rst > +++ b/Documentation/kbuild/makefiles.rst > @@ -319,6 +319,20 @@ more details, with real examples. > that directory specifies obj-y, those objects will be left orphan. > It is very likely a bug of the Makefile or of dependencies in Kconfig. > > + Kbuild also supports dedicated syntax, subdir-y and subdir-m, for > + descending into subdirectories. It is a good fit when you know they > + do not contain kernel-space objects at all. A typical usage is to let > + Kbuild descend into subdirectories to build tools. > + > + Examples:: > + > + subdir-$(CONFIG_GCC_PLUGINS) += gcc-plugins > + subdir-$(CONFIG_MODVERSIONS) += genksyms > + subdir-$(CONFIG_SECURITY_SELINUX) += selinux > + > + Unlike obj-y/m, subdir-y/m does not need the trailing slash since this > + syntax is always used for directories. > +
Just curious: Is a trailing slash allowed here? say for consistency? > It is good practice to use a `CONFIG_` variable when assigning directory > names. This allows kbuild to totally skip the directory if the > corresponding `CONFIG_` option is neither 'y' nor 'm'. > Reviewed-by: Randy Dunlap <rdun...@infradead.org> thanks. -- ~Randy
