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    SubjectRe: Please revert "debug: Make CONFIG_EXPERT select CONFIG_DEBUG_KERNEL to unhide debug options"
    On Mon, Oct 10, 2011 at 09:29:48AM +0200, Ingo Molnar wrote:
    > * Adrian Bunk <bunk@stusta.de> wrote:
    >...
    > I think you are wrong not just about that detail but about the whole
    > premise of your complaint as well:
    >
    > > 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.
    >
    > Not really - it's a debugging-only option and when i turn on
    > CONFIG_DEBUG_KERNEL I expect to have full config control over all
    > debug options - with sane defaults provided.

    Then you would have to remove the dependency on EXPERT from the prompt,
    and allow unsetting DEBUG_BUGVERBOSE with EXPERT=n, DEBUG_KERNEL=y.

    Note that this is completely unrelated to the commit we are discussing,
    since commit f505c553 has no effect in the EXPERT=n case you are
    discussing here.

    > I definitely don't want a debugging option to depend on
    > CONFIG_EXPERT.

    DEBUG_BUGVERBOSE does not depend on EXPERT.

    But EXPERT is currently required for disabling it.

    This part of our discussion boils down to the following options:
    1. DEBUG_KERNEL allows a user to enable additional debugging
    2. DEBUG_KERNEL gives a user full control over all debug options

    Traditionally it was 1., to tell a user reporting a bug that he should
    enable additional debugging in his kernel - without him accidentally
    disabling useful debugging.

    Again, this part of the discussion is unrelated to commit f505c553.

    > CONFIG_EXPERT is a superset to all that: it implies config control
    > over all debug options *and* over many other kernel components as
    > well.

    I don't see the advantage that EXPERT=y is now unconditionally enabling
    the DEBUG_KERNEL knob.

    When I am an "expert", why can't I still decide myself globally if I
    want to enable more debugging or not?

    Another problem is that we have code using "#ifdef CONFIG_DEBUG_KERNEL"
    so enabling EXPERT for making your kernel smaller can make your kernel
    bigger, but such usages should anyway get own config options.

    > This is a pretty easy model to think about.

    There are many options in the kernel that only enable seeing other
    config options.

    With that model, shouldn't EXPERT also have
    select MISC_FILESYSTEMS
    and many other similar select's?

    The point I am trying to make here is that there are many convenience
    config options that only exist to allow a user to hide a bunch of
    options he is not interested in, and DEBUG_KERNEL is one of them. [1]

    > > The crazy select added in commit f505c553 is wrong.
    >
    > Why? Your original message does not explain it.

    It is not needed for what it was claimed it was needed for,
    and it is a bad idea in general.

    If I didn't explain that properly that was my fault,
    I hope the explanation in this email is better.

    > Thanks,
    >
    > Ingo

    cu
    Adrian

    [1] ignoring the buggy code using "#ifdef CONFIG_DEBUG_KERNEL"

    --

    "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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