pkg-kconfig: add missing -patch dependency for defconfig

Since the introduction of _KCONFIG_DEFCONFIG in 8ef62b99, the package's
.config file no longer depends on anything (unless a fragment is
defined). Therefore, there is no dependency anymore between .config
and <pkg>-patch. Thus, it is possible that the .config file is
attempted to be built before the package is extracted and patched.
Usually this works out OK because <pkg>-patch will always be done
before <pkg>-configure, but it will fail when the user calls
<pkg>-menuconfig explicitly. It will also fail when we enable
top-level parallel build.

To solve this, just add an explicit order-only dependency on
<pkg>-patch. It really is only necessary when _KCONFIG_DEFCONFIG is
defined and _KCONFIG_FRAGMENT_FILES is not, but it doesn't hurt to
add it unconditionally.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Reported-by: FrAnKenStEiN MC <chfakht@gmail.com>
---
 package/pkg-kconfig.mk | 5 +++++
 1 file changed, 5 insertions(+)

Arnout, All,

On 2016-01-24 23:58 +0100, Arnout Vandecappelle (Essensium/Mind) spake thusly:
> Since the introduction of _KCONFIG_DEFCONFIG in 8ef62b99, the package's
> .config file no longer depends on anything (unless a fragment is
> defined). Therefore, there is no dependency anymore between .config
> and <pkg>-patch. Thus, it is possible that the .config file is
> attempted to be built before the package is extracted and patched.
> Usually this works out OK because <pkg>-patch will always be done
> before <pkg>-configure, but it will fail when the user calls
> <pkg>-menuconfig explicitly. It will also fail when we enable
> top-level parallel build.
> 
> To solve this, just add an explicit order-only dependency on
> <pkg>-patch. It really is only necessary when _KCONFIG_DEFCONFIG is
> defined and _KCONFIG_FRAGMENT_FILES is not, but it doesn't hurt to
> add it unconditionally.
> 
> Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
> Reported-by: FrAnKenStEiN MC <chfakht@gmail.com>
> ---
>  package/pkg-kconfig.mk | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/package/pkg-kconfig.mk b/package/pkg-kconfig.mk
> index eaee572..90f3f9f 100644
> --- a/package/pkg-kconfig.mk
> +++ b/package/pkg-kconfig.mk
> @@ -72,6 +72,11 @@ $$($(2)_DIR)/.config: $$($(2)_KCONFIG_FILE) $$($(2)_KCONFIG_FRAGMENT_FILES)
>  	$$(Q)yes "" | $$($(2)_MAKE_ENV) $$(MAKE) -C $$($(2)_DIR) \
>  		$$($(2)_KCONFIG_OPTS) oldconfig
>  
> +# If _KCONFIG_FILE or _KCONFIG_FRAGMENT_FILES exists, this dependency is
> +# already implied, but if we only have a _KCONFIG_DEFCONFIG we have to add
> +# it explicitly. It doesn't hurt to always have it though.
> +$$($(2)_DIR)/.config: | $(1)-patch

I don't understand why this is needed.

On line 65, we have;
    $$($(2)_DIR)/.config: $$($(2)_KCONFIG_FILE) $$($(2)_KCONFIG_FRAGMENT_FILES)

and on line 52;
    $$($(2)_KCONFIG_FILE) $$($(2)_KCONFIG_FRAGMENT_FILES): | $(1)-patch

So, unless I'm missing something, $$($(2)_DIR)/.config already has a
dependency on $(1)-patch via $$($(2)_KCONFIG_FILE)

Oh, damn, I see it now... Grr...

OK, so what made me understand is the comment in the code:

   [...] if we only have a _KCONFIG_DEFCONFIG [...]

Ok, so it goes thusly:

  - if using a defconfig file, we do not have a $(2)_KCONFIG_FILE

  - if at the same time, we have no fragments, we have no rule from
    .config to $(1)-patch.

OK, fine by me. Thanks!

Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

Regards,
Yann E. MORIN.

>  # In order to get a usable, consistent configuration, some fixup may be needed.
>  # The exact rules are specified by the package .mk file.
>  define $(2)_FIXUP_DOT_CONFIG
> -- 
> 2.7.0
> 
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> buildroot mailing list
> buildroot@busybox.net
> http://lists.busybox.net/mailman/listinfo/buildroot

Dear Arnout Vandecappelle (Essensium/Mind),

On Sun, 24 Jan 2016 23:58:42 +0100, Arnout Vandecappelle
(Essensium/Mind) wrote:
> Since the introduction of _KCONFIG_DEFCONFIG in 8ef62b99, the package's
> .config file no longer depends on anything (unless a fragment is
> defined). Therefore, there is no dependency anymore between .config
> and <pkg>-patch. Thus, it is possible that the .config file is
> attempted to be built before the package is extracted and patched.
> Usually this works out OK because <pkg>-patch will always be done
> before <pkg>-configure, but it will fail when the user calls
> <pkg>-menuconfig explicitly. It will also fail when we enable
> top-level parallel build.
> 
> To solve this, just add an explicit order-only dependency on
> <pkg>-patch. It really is only necessary when _KCONFIG_DEFCONFIG is
> defined and _KCONFIG_FRAGMENT_FILES is not, but it doesn't hurt to
> add it unconditionally.
> 
> Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
> Reported-by: FrAnKenStEiN MC <chfakht@gmail.com>
> ---
>  package/pkg-kconfig.mk | 5 +++++
>  1 file changed, 5 insertions(+)

Applied, thanks.

Thomas