[Buildroot] [PATCH v6] core/pkg-kconfig: Use olddefconfig when available

[Yann E. MORIN <yann.morin.1998@free.fr>]

Romain, All,

On 2016-04-20 11:54 +0200, Romain Izard spake thusly:
> Using 'yes "" | make oldconfig' to regenerate a .config file from an
> existing defconfig does not work reliably in all cases. Specifically, it
> does not work well with tristate choice entries.
> 
> The correct way to do it is to use 'make olddefconfig', but this target
> is not supported in projects that use an old version of kconfig. As
> most projects do not use tristate entries, there is no need for them to
> upgrade.
> 
> 'oldnoconfig' is an alias for 'olddefconfig', but it also is the only
> name for this target between Linux versions 2.6.36 and 3.6.
> 
> Check which targets are supported by the current project, and use the
> appropriate method to regenerate the .config file.
> 
> Signed-off-by: Romain Izard <romain.izard.pro@gmail.com>
> Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
> ---
> Changelog:
> v1: New patch
> v2: Use oldnoconfig instead of olddefconfig
>     Fix silent mode
>     Change the pattern in both places where it is used
>     Use a macro to avoid redundancy
> v3: Do not use $(call ...)
>     Use the $(2)_KCONFIG_MAKE variable
> v4: No change
> v5: Detect available methods and use the most recent one
> v6: Remove colon from matched rule names
> 
>  package/pkg-kconfig.mk | 25 +++++++++++++++++++++----
>  1 file changed, 21 insertions(+), 4 deletions(-)
> 
> diff --git a/package/pkg-kconfig.mk b/package/pkg-kconfig.mk
> index 4033915..478f5bb 100644
> --- a/package/pkg-kconfig.mk
> +++ b/package/pkg-kconfig.mk
> @@ -60,18 +60,35 @@ $$($(2)_KCONFIG_FILE) $$($(2)_KCONFIG_FRAGMENT_FILES): | $(1)-patch
>  $(2)_KCONFIG_MAKE = \
>  	$$($(2)_MAKE_ENV) $$(MAKE) -C $$($(2)_DIR) $$($(2)_KCONFIG_OPTS)
>  
> +$(2)_KCONFIG_RULES = \
> +	$$(shell $$($(2)_KCONFIG_MAKE) -pn config 2>/dev/null | \
> +		sed 's/^\([_0-9a-zA-Z]*config\):.*/\1/ p; d')

Ok, so... Well... Err...

Could you respin v4 of the patch, the one that used something like:

    make oldnoconfig || (yes "" |make oldconfig)

please? ;-)

OK, what's wrong with my proposal? It works in an unconfigured tree.
But as soon as the tree is configured, it breaks, notably with older
kernels, like 3.0.

    $ cd linux-3.0
    $ make -qpn oldefconfig 2>/dev/null |grep olddefconfig
    [nothing]
    $ touch .config
    $ make -qpn oldefconfig 2>/dev/null |grep olddefconfig
    olddefconfig: scripts_basic outputmakefile FORCE

But 3.0 does not have olddefconfig. It's jsut the %config generic rule
kicking in. So we'd believe there would be support for olddefconfig (or
oldnoconfig) when there isn't.

So, I have to apologise for the delusion. Your v4 is the best we can do.

Thank you! :-)

Regards,
Yann E. MORIN.

> +# The correct way to regenerate a .config file is to use 'make olddefconfig'.
> +# For historical reasons, the target name is 'oldnoconfig' between Linux kernel
> +# versions 2.6.36 and 3.6, and remains as an alias in later versions.
> +# In older versions, and in some other projects that use kconfig, the target is
> +# not supported at all, and we use 'yes "" | make oldconfig' as a fallback
> +# only, as this can fail in complex cases.
> +define $(2)_REGEN_DOT_CONFIG
> +	$$(if $$(filter olddefconfig,$$($(2)_KCONFIG_RULES)),
> +		$$(Q)$$($(2)_KCONFIG_MAKE) olddefconfig,
> +		$$(if $$(filter oldnoconfig,$$($(2)_KCONFIG_RULES)),
> +			$$(Q)$$($(2)_KCONFIG_MAKE) oldnoconfig,
> +			$$(Q)(yes "" | $$($(2)_KCONFIG_MAKE) oldconfig)))
> +endef
> +
>  # The specified source configuration file and any additional configuration file
>  # fragments are merged together to .config, after the package has been patched.
>  # Since the file could be a defconfig file it needs to be expanded to a
> -# full .config first. We use 'make oldconfig' because this can be safely
> -# done even when the package does not support defconfigs.
> +# full .config first.
>  $$($(2)_DIR)/.config: $$($(2)_KCONFIG_FILE) $$($(2)_KCONFIG_FRAGMENT_FILES)
>  	$$(Q)$$(if $$($(2)_KCONFIG_DEFCONFIG), \
>  		$$($(2)_KCONFIG_MAKE) $$($(2)_KCONFIG_DEFCONFIG), \
>  		cp $$($(2)_KCONFIG_FILE) $$(@))
>  	$$(Q)support/kconfig/merge_config.sh -m -O $$(@D) \
>  		$$(@) $$($(2)_KCONFIG_FRAGMENT_FILES)
> -	$$(Q)yes "" | $$($(2)_KCONFIG_MAKE) oldconfig
> +	$$($(2)_REGEN_DOT_CONFIG)
>  
>  # If _KCONFIG_FILE or _KCONFIG_FRAGMENT_FILES exists, this dependency is
>  # already implied, but if we only have a _KCONFIG_DEFCONFIG we have to add
> @@ -82,7 +99,7 @@ $$($(2)_DIR)/.config: | $(1)-patch
>  # The exact rules are specified by the package .mk file.
>  define $(2)_FIXUP_DOT_CONFIG
>  	$$($(2)_KCONFIG_FIXUP_CMDS)
> -	$$(Q)yes "" | $$($(2)_KCONFIG_MAKE) oldconfig
> +	$$($(2)_REGEN_DOT_CONFIG)
>  	$$(Q)touch $$($(2)_DIR)/.stamp_kconfig_fixup_done
>  endef
>  
> -- 
> 2.5.0
> 

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