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    Subject[PATCH 0/5] RFC: strip 15,000 lines from a typical autoconf.h
    Some linux-next builds were showing thousands of repeated warnings like:

    linux/netdevice.h:964:1: warning: "__enabled_CONFIG_FCOE" is not defined [-Wundef]

    An example is at:

    TonyB proposed a fix, and DaveM indicated IS_ENABLED should be fixed
    instead. [ ]

    This got me looking at IS_ENABLED, and I realized that to support using
    this thing in C code, it was bloating our autoconf.h header file by
    about 15,000 lines. Ouch. And it still doesn't have all the possible
    lines in it, otherwise we'd not see warnings like the above.

    If we limit its use to just CPP #if ... directives, we can unwind the
    bloat and get down to less than ~1k of lines.

    Fortunately IS_ENABLED is fairly new, and of the ~300 instances, only
    a handful are actually in C code, so it is easy to unwind those.

    The other downside of C users, I thought while unwinding the above users,
    is that the use of IS_ENABLED on Kconfig bools in C if (...) conditionals
    can give the misleading impression that the two code paths will exist in
    the binary, and that the path is chosen at runtime (which it is not).

    Commits 1 --> 4 are just largely unwind, so if you are going to just
    look at one, please skip to commit #5 and read the commit log there,
    as it has more details on how this bloat all came about.

    I want to test this more, but I also wanted to get some initial
    feedback in case I'm completely barking up the wrong tree here.

    Commit ce1744f4ed20ca8 seems to endorse C users of IS_ENABLED, and
    it went through Linus and Andrew, so I'm not sure scrapping C users
    as a solution will be universally agreeable...


    Paul Gortmaker (5):
    ARM: remove C users of IS_ENABLED on THUMB2_KERNEL
    drivers/net: remove IS_ENABLED usage from wiznet drivers
    Revert "kconfig: fix __enabled_ macros definition for invisible and
    un-selected symbols"
    kconfig: limit IS_ENABLED & similar to CPP usage

    arch/arm/include/asm/opcodes.h | 6 ++++
    arch/arm/kernel/ftrace.c | 9 +-----
    arch/arm/kernel/insn.c | 9 +++---
    arch/arm/kernel/kprobes.c | 34 ++++++++++++------------
    arch/arm/kernel/patch.c | 28 ++++++++++---------
    drivers/net/ethernet/wiznet/w5100.c | 9 ++++--
    drivers/net/ethernet/wiznet/w5300.c | 18 ++++++++----
    include/linux/kconfig.h | 8 +++---
    include/linux/migrate.h | 2 +
    mm/mprotect.c | 2 +-
    mm/rmap.c | 7 ++---
    scripts/kconfig/confdata.c | 49 +++++++++-------------------------
    12 files changed, 86 insertions(+), 95 deletions(-)


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