[Buildroot] [PATCH v5] core/pkg-kconfig: Use olddefconfig when available

Yann E. MORIN yann.morin.1998 at free.fr
Tue Apr 19 17:45:55 UTC 2016


Romain, All,

On 2016-04-19 17:07 +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 at gmail.com>
> Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout at mind.be>
> ---
> 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
> 
>  package/pkg-kconfig.mk | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/package/pkg-kconfig.mk b/package/pkg-kconfig.mk
> index 4033915..e14b33f 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')

NAK, because this will be executed at the time the package rules are
exapnded (i.e. during the call to $(eval $(kconfig-package)), so would
not work for a build from scratch...

(but double-dollar make that assertion difficult to asses... I'd have to
double-check).

Besides...

> +# 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

... this would get expand twice, so the shell construct would be run
twice, whereas doing it all in shell as I suggested would only run the
needed checks: if olddefconfig is supported, the check for oldnoconfig
would no even run; in your case, both tests would be run, always.

But yeah, my proposal had a flaw; even my fix on that proposal had a
flaw: the output of the grep should not be >/dev/null, since we want to
check whether it isempty or not...

Regards,
Yann E. MORIN.

>  # 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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