Messages in this thread | | | Subject | Re: [PATCH 2/2] Enable 'make CONFIG_FOO=y oldconfig' | From | David Woodhouse <> | Date | Wed, 10 Aug 2011 14:07:36 +0100 |
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On Wed, 2011-08-10 at 14:59 +0200, Michal Marek wrote: > I wasn't talking about the env= syntax, but about > > make CONFIG_EXT2_FS=m all > which makes kbuild visit fs/ext2 even if CONFIG_EXT2_FS is disabled in > .config. With no update of the configuration or checking the dependencies. > > Hm, actually this would be a problem even if kconfig does read the > CONFIG_* variables from the environment, because it could result in a > mismatch if kconfig determines that the variable cannot be set, but make > still sees it in the environment. So we would have to use 'undefine > CONFIG_FOO' instead of '# CONFIG_FOO is not set' in > include/config/auto.conf, to be able to properly support make CONFIG_FOO=y.
That's always been true; it's *always* been broken like that.
But now we're actually *encouraging* people to start setting CONFIG_FOO=y in the environment or the make command line, so we should certainly make it more robust.
It should be simple enough to force a reconfig if CONFIG_* is specified in the environment.
Actually, while we're at it let's stop just picking it up from the environment and pick it up *only* if it's overridden in the make flags.
Something like this will list the variables which are overridden on the command line:
CONFIG_OVERRIDES := $(patsubst line:%,%,$(filter line:%,$(foreach var, $(filter CONFIG_%,$(.VARIABLES)), $(origin $(var)):$(var))))
Then we can make auto.conf.cmd trigger a reconfig if it's non-empty, and make the kconfig tool allow overrides *only* for those variables specified in $CONFIG_OVERRIDES... which avoids any worries about "stray" environment variables too.
I'll see if I can clean the above expression up and do that. -- David Woodhouse Open Source Technology Centre David.Woodhouse@intel.com Intel Corporation
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