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    SubjectRe: Please revert "debug: Make CONFIG_EXPERT select CONFIG_DEBUG_KERNEL to unhide debug options"
    On Fri, Sep 30, 2011 at 08:05:19AM -0700, Josh Triplett wrote:
    > On Fri, Sep 30, 2011 at 04:42:45PM +0300, Adrian Bunk wrote:
    >...
    > > Let me point at the obvious fact that both CONFIG_DEBUG_BUGVERBOSE and
    > > CONFIG_DEBUG_RODATA do depend on DEBUG_KERNEL, and are contrary to the
    > > claim of the author of this patch never enabled with
    > > CONFIG_DEBUG_KERNEL=n. [1]
    >
    > Not true:
    >
    > ~/src/linux-2.6$ rm .config
    > ~/src/linux-2.6$ make allnoconfig
    > HOSTCC scripts/basic/fixdep
    > HOSTCC scripts/kconfig/conf.o
    > HOSTCC scripts/kconfig/zconf.tab.o
    > HOSTLD scripts/kconfig/conf
    > scripts/kconfig/conf --allnoconfig Kconfig
    > #
    > # configuration written to .config
    > #
    > ~/src/linux-2.6$ grep BUGVERBOSE .config
    > CONFIG_DEBUG_BUGVERBOSE=y
    > ~/src/linux-2.6$ grep DEBUG_KERNEL .config
    > # CONFIG_DEBUG_KERNEL is not set
    >
    > DEBUG_BUGVERBOSE does not depend on DEBUG_KERNEL; it just only shows up
    > with DEBUG_KERNEL (and EXPERT) set. The *description* has a conditional
    > on DEBUG_KERNEL and EXPERT:
    >
    > config DEBUG_BUGVERBOSE
    > bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
    >...

    Apologies, I was wrong on DEBUG_BUGVERBOSE
    (but for DEBUG_RODATA I was right).

    >...
    > Also see Ingo Molnar's mail with Message-Id
    > <20110605093445.GA19927@elte.hu>, which explicitly recommended this
    > approach.

    Ingo is an expert in a gazillion areas of the kernel and knows more
    about these than mere mortals like me will ever know.

    Kconfig is (the?) one thing where he in not a good advisor.

    Looking at the patch Frederic points at [1]:

    config DEBUG_BUGVERBOSE
    - bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
    + bool "Verbose BUG() reporting (adds 70K)" if EXPERT

    This part of the patch would have been the correct and complete
    solution for DEBUG_BUGVERBOSE.

    The crazy select added in commit f505c553 is wrong.

    > - Josh Triplett

    cu
    Adrian

    [1] http://lkml.org/lkml/2011/6/6/641

    --

    "Is there not promise of rain?" Ling Tan asked suddenly out
    of the darkness. There had been need of rain for many days.
    "Only a promise," Lao Er said.
    Pearl S. Buck - Dragon Seed



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