Re: [PATCH v2 2/2] kbuild: move KALLSYMS_EXTRA_PASS from Kconfig to Makefile

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On 5.4.2011 12:24, Artem Bityutskiy wrote:
From: Artem Bityutskiy<Artem.Bityutskiy@xxxxxxxxx>

At the moment we have the CONFIG_KALLSYMS_EXTRA_PASS Kconfig switch,
which users can enable or disable while configuring the kernel. This
option is then used by 'make' to determine whether an extra kallsyms
pass is needed or not.

However, this approach is not nice and confusing, and this patch moves
CONFIG_KALLSYMS_EXTRA_PASS from Kconfig to Makefile instead. The
rationale is below.

1. CONFIG_KALLSYMS_EXTRA_PASS is really about the build time, not
    run-time. There is no real need for it to be in Kconfig. It is
    just an additional work-around which should be used only in rare
    cases, when someone breaks kallsyms, so Kbuild/Makefile is much
    better place for this option.
2. Grepping CONFIG_KALLSYMS_EXTRA_PASS shows that many defconfigs have
    it enabled, probably not because they try to work-around a kallsyms
    bug, but just because the Kconfig help text is confusing and does
    not really make it clear that this option should not be used unless
    except when kallsyms is broken.
3. And since many people have CONFIG_KALLSYMS_EXTRA_PASS enabled in
    their Kconfig, we do might fail to notice kallsyms bugs in time. E.g.,
    many testers use "make allyesconfig" to test builds, which will enable
    CONFIG_KALLSYMS_EXTRA_PASS and kallsyms breakage will not be noticed.

To address that, this patch:

1. Kills CONFIG_KALLSYMS_EXTRA_PASS
2. Changes Makefile so that people can use "make KALLSYMS_EXTRA_PASS=1"
    to enable the extra pass if needed. Additionally, they may define
    KALLSYMS_EXTRA_PASS as an environment variable.
3. By default KALLSYMS_EXTRA_PASS is disabled and if kallsyms has issues,
    "make" should print a warning and suggest using KALLSYMS_EXTRA_PASS
4. Add "make help" entry for KALLSYMS_EXTRA_PASS

I merged the patches, but removed the make help text. Rationale: People who don't need it don't need the help text, for those that need it the help text wouldn't provide more information than the error message. Is this OK with you?

Michal
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