[Buildroot] [PATCH] docs/manual: mention Config.in in LIBFOO_DEPENDENCIES

[Buildroot] [PATCH] docs/manual: mention Config.in in LIBFOO_DEPENDENCIES

[Łukasz Stelmach]

Mention the need for a parallel dependency specification
in both *_DEPENDENCIES variables in .mk files as well as
in Config.in files using select and/or depends on.

Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>
---
 docs/manual/adding-packages-generic.adoc | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

I am not sure this is actually true, but if it is, I figure it worth
mentioning.

diff --git a/docs/manual/adding-packages-generic.adoc b/docs/manual/adding-packages-generic.adoc
index f0b0508f53..9b91351138 100644
--- a/docs/manual/adding-packages-generic.adoc
+++ b/docs/manual/adding-packages-generic.adoc
@@ -371,7 +371,10 @@ not and can not work as people would expect it should:
   However, modifications to configuration of these dependencies will
   not force a rebuild of the current package. In a similar way,
   +HOST_LIBFOO_DEPENDENCIES+ lists the dependencies for the current
-  host package.
+  host package. In all cases (+LIBFOO_DEPENDENCIES+,
+  +HOST_LIBFOO_DEPENDENCIES+ as well as the variables below) the
+  dependencies need to be specified in parallel with +select+ or
+  +depends on+ in the +Config.in+ file.
 
 * +LIBFOO_EXTRACT_DEPENDENCIES+ lists the dependencies (in terms of
   package name) that are required for the current target package to be
-- 
2.39.5

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Re: [Buildroot] [PATCH] docs/manual: mention Config.in in LIBFOO_DEPENDENCIES

[Thomas Petazzoni via buildroot]

Hello Łukasz,

Thanks for your contribution!

On Wed, 14 May 2025 21:09:42 +0200
Łukasz Stelmach <l.stelmach@samsung.com> wrote:

> Mention the need for a parallel dependency specification
> in both *_DEPENDENCIES variables in .mk files as well as
> in Config.in files using select and/or depends on.
> 
> Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>
> ---
>  docs/manual/adding-packages-generic.adoc | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> I am not sure this is actually true, but if it is, I figure it worth
> mentioning.

Unfortunately, the reality is more complicated than that:

- For host packages, having a package in HOST_LIBFOO_DEPENDENCIES does
  *NOT* require having a select or depends on for this dependency.
  Indeed, most host packages don't even have a Config.in.host option.

- For target packages, having a "select BAR" does not necessarily imply
  that "bar" must be in LIBFOO_DEPENDENCIES. Indeed, perhaps "bar" is
  only a runtime dependency of libfoo.

Therefore, the story is more complicated than the update you're
proposing for the documentation.

> diff --git a/docs/manual/adding-packages-generic.adoc b/docs/manual/adding-packages-generic.adoc
> index f0b0508f53..9b91351138 100644
> --- a/docs/manual/adding-packages-generic.adoc
> +++ b/docs/manual/adding-packages-generic.adoc
> @@ -371,7 +371,10 @@ not and can not work as people would expect it should:
>    However, modifications to configuration of these dependencies will
>    not force a rebuild of the current package. In a similar way,
>    +HOST_LIBFOO_DEPENDENCIES+ lists the dependencies for the current
> -  host package.
> +  host package. In all cases (+LIBFOO_DEPENDENCIES+,
> +  +HOST_LIBFOO_DEPENDENCIES+ as well as the variables below) the
> +  dependencies need to be specified in parallel with +select+ or
> +  +depends on+ in the +Config.in+ file.

Perhaps:

"Note that for target packages, all packages listed in
+LIBFOO_DEPENDENCIES+ must be enabled from a Config.in point in view,
either using +select+ or +depends on+ dependencies" or something like this?

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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