[lkml]   [2007]   [Nov]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    Patch in this message
    Subject[RFC: 2.6 patch] add -fno-tree-scev-cprop to KBUILD_CFLAGS
    The gcc from svn that will become gcc 4.3 generates libgcc calls in 
    cases like the following (on 32bit architectures):

    <-- snip -->

    static inline void timespec_add_ns(struct timespec *a, u64 ns)
    while(ns >= NSEC_PER_SEC) {
    ns -= NSEC_PER_SEC;

    <-- snip -->

    It can make sense to emit assembler code doing division for such C code -
    that doesn't seem to be something that would generally be wrong.

    But the kernel does (at least on some architectures) not link with
    libgcc or ship other code providing the required libgcc functions.

    Richard Guenther suggested in gcc bug #32044 to use -fno-tree-scev-cprop
    (new option in gcc 4.3) as a workaround and I confirmed that it fixes
    the compilation.

    Signed-off-by: Adrian Bunk <>

    diff --git a/Makefile b/Makefile
    index e28dde8..9d8a831 100644
    --- a/Makefile
    +++ b/Makefile
    @@ -527,6 +527,9 @@ KBUILD_CFLAGS += $(call cc-option,-Wdeclaration-after-statement,)
    # disable pointer signed / unsigned warnings in gcc 4.0
    KBUILD_CFLAGS += $(call cc-option,-Wno-pointer-sign,)

    +# workaround to avoid gcc 4.3 emitting libgcc calls (see gcc bug #32044)
    +KBUILD_CFLAGS += $(call cc-option,-fno-tree-scev-cprop,)
    # Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments
    # But warn user when we do so
    warn-assign = \
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2007-11-11 07:53    [W:0.022 / U:78.516 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site