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

Yann E. MORIN yann.morin.1998 at free.fr
Tue May 3 21:39:50 UTC 2016


Arnout, All,

On 2016-05-03 23:20 +0200, Arnout Vandecappelle spake thusly:
> On 05/02/16 10:36, Romain Izard wrote:
> >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: "Yann E. MORIN" <yann.morin.1998 at free.fr>
> 
> Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout at mind.be>
> 
>  We definitely want this in 2016.05.

Indeed.

> >---
> >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
> 
>  I have been thinking about how to do more in shell after all. It could be
> done by moving most of it to a support shell script:
> 
> 
> define $(2)_REGEN_DOT_CONFIG
> 	$(Q)$$($(2)_MAKE_ENV) support/scripts/makeolddefconfig \
> 		$$(MAKE) -C $$($(2)_DIR) $$($(2)_KCONFIG_OPTS)
> endef
> 
> 
> and support/scripts/makeolddefconfig:
> 
> kconfig_rules=$("$@"  -pn config 2>/dev/null | sed ...)
> 
> if echo "$kconfig_rules" | grep -q olddefconfig; then
> 	"$@" olddefconfig
> elif echo "$kconfig_rules" | grep -q oldnoconfig; then
> 	"$@" oldnoconfig
> else
> 	yes "" | "$@" oldconfig
> fi
> 
> 
>  However, bottom line I don't think this improves the situation sufficiently

No, I don't think it does. I'm not opposed to using support scripts, but
in this case I don't think it is really needed.

I did prefer the shell construct in the Makefile, because it is a bit
easier to read than the make construct, but it does not work and it's
not like the make construct is totally unreadable.

Regards,
Yann E. MORIN.

>  Regards,
>  Arnout
> 
> 
> >+
> > # 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
> >
> >
> 
> 
> -- 
> 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
> GPG fingerprint:  7493 020B C7E3 8618 8DEC 222C 82EB F404 F9AC 0DDF

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