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

[Arnout Vandecappelle <arnout@mind.be>]

On 04/19/16 22:35, Yann E. MORIN wrote:
> Romain, All,
>
> On 2016-04-19 19:45 +0200, Yann E. MORIN spake thusly:
>> 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@gmail.com>
>>> Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@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).
>
> OK, so I withdraw that comment: it *does* work. And the second shell
> eval is only called when needed! :-)
>
> Still, I'm not too fond of it being written in Makefile. Especially the
> part below...
>
>> 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
>
> I am not usually one to argue against writting Makefile code in a
> Makefile. However, for this case, I think writting a shell rule is much
> more readable.

  +1 to that.

  And as Thomas said: my Rev-by no longer applies.

  Regards,
  Arnout

>
> And I don't see how your solution would be inherently different from
> mine: both use 'make -pqn' to get the list of targets and grep/sed the
> output to decide if the requested target exists...
>
> By the way, if your sed expression would have moved the colon ':'
> outside the ()-expression, you would not have had to repeqt the colon in
> the filter match. Also, using extended regexps would allow using
> character classes.
>
>      $(2)_KCONFIG_RULES = \
>          $$(shell $$($(2)_KCONFIG_MAKE) -pn config 2>/dev/null | \
>              sed -r '/^([[:alnum:]]*config):.*/!d; s//\1/;')
>
> Again, I think a shell construct is either to read.
>
> 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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-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
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