[Buildroot] [PATCH v8] core/pkg-kconfig: Use olddefconfig when available

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

Romain, All,

On 2016-05-02 10:36 +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>

Tested with:
  - linux 4.5.2        -> olddefconfig
  - linux 3.6.11       -> oldnoconfig
  - linux 2.6.31.14    -> oldconfig
  - busybox 1.24.2     -> oldconfig
  - basrebox 2016.04.0 -> olddefconfig

The test was done with and without libtirpc enabled, and the busybox
configuration went OK.

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

Thanks Romain! :-)

Note however that there is a spurious errior mesage on the console (but
it is not due to this patch):

    /bin/sh: /home/ymorin/dev/buildroot/O/host/usr/bin/pkg-config: No
    such file or directory

... which is repeated multiple times.

This is because, with libtirpc enabled, when we run "make busybox-menuconfig"
from a clean tree (ie.e right after "make menuconfig"), host-pkgconf is
not built.

We should probably redirect those error messages to /dev/null, no?

Regards,
Yann E. MORIN.

> ---
> 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
> v7: Shell-based conditons, does not work with backticks
> v8: Return to v6, with more comments
> 
>  package/pkg-kconfig.mk | 34 ++++++++++++++++++++++++++++++----
>  1 file changed, 30 insertions(+), 4 deletions(-)
> 
> diff --git a/package/pkg-kconfig.mk b/package/pkg-kconfig.mk
> index 4033915..f32a198 100644
> --- a/package/pkg-kconfig.mk
> +++ b/package/pkg-kconfig.mk
> @@ -60,18 +60,44 @@ $$($(2)_KCONFIG_FILE) $$($(2)_KCONFIG_FRAGMENT_FILES): | $(1)-patch
>  $(2)_KCONFIG_MAKE = \
>  	$$($(2)_MAKE_ENV) $$(MAKE) -C $$($(2)_DIR) $$($(2)_KCONFIG_OPTS)
>  
> +# $(2)_KCONFIG_MAKE may already rely on shell expansion. As the $() syntax
> +# of the shell conflicts with Make's own syntax, this means that backticks
> +# are used with those shell constructs. Unfortunately, the backtick syntax
> +# does not nest, and we need to use Make instead of the shell to handle
> +# conditions.
> +
> +# A recursively expanded variable is necessary, to be sure that the shell
> +# command is called when the rule is processed during the build and not
> +# when the rule is created when parsing all packages.
> +$(2)_KCONFIG_RULES = \
> +	$$(shell $$($(2)_KCONFIG_MAKE) -pn config 2>/dev/null | \
> +		sed 's/^\([_0-9a-zA-Z]*config\):.*/\1/ p; d')
> +
> +# 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
> +	$$($(2)_REGEN_DOT_CONFIG)
>  
>  # If _KCONFIG_FILE or _KCONFIG_FRAGMENT_FILES exists, this dependency is
>  # already implied, but if we only have a _KCONFIG_DEFCONFIG we have to add
> @@ -82,7 +108,7 @@ $$($(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
>  
> -- 
> 2.7.4
> 

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