[Buildroot] [Bug 8156] pkg-kconfig infra broken for *-update-{config, defconfig}

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=8156

--- Comment #3 from Yann E. MORIN <yann.morin.1998 at free.fr> 2015-06-04 17:12:53 UTC ---
Thomas,

> I'm a bit confused. On the bug report, you say that you cannot reproduce,
> but on IRC, you were apparently saying that you could reproduce and that
> it wasn't indeed a use case that hadn't been planned.

Well, I first did a quick review of the code, on which I reported on
IRC. That led me thinking it was indeed broken.

Then I actually tested your use-case, and was not able to reproduce.

Sorry for the confusion. I stand by the comment I made here on the
tracker: I can not reproduce, and I can't see why it is broken.

So, let's look at the code (after partially expanding variables in
package/pkg-kconfig.mk); we have this dependency chain:

    .PHONY: linux-update-config linux-savedefconfig

    linux-update-config: linux-savedefconfig

    linux-savedefconfig: $(LINUX_DIR)/.stamp_kconfig_fixup_done

    $(LINUX_DIR)/.stamp_kconfig_fixup_done: $(LINUX_DIR)/.config

    $(LINUX_DIR)/.config: $(LINUX_KCONFIG_FILE)

So in your case:

  - $(LINUX_KCONFIG_FILE) initially points to the bundled defconfig
    file, and the dependency chain is satisfied;

  - then you change it to point to an arbitrary filename, and the
    dependency chain is now broken, because that file does not yet
    exist;

  - but (because linux-update-config and linux-savedefconfig are .PHONY?)
    it is not a problem for make; at least it is not for my make-3.81.

What's your make version?

> Who should I trust? The y_morin on IRC, or the Yann E. Morin in the bug
> tracker ? :-)

Eh! ;-)

Regards,
Yann E. MORIN.

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