Re: [PATCH 7/7] kbuild: doc: document subdir-y syntax

[Randy Dunlap <rdunlap@infradead.org>]

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 <masahiroy@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 <rdunlap@infradead.org>

thanks.

-- 
~Randy