• Chris Metcalf's avatar
    lib/clz_tab.c: put in lib-y rather than obj-y · f5948701
    Chris Metcalf authored
    The clz table (__clz_tab) in lib/clz_tab.c is also provided as part of
    libgcc.a, and many architectures link against libgcc.  To allow the
    linker to avoid a multiple-definition link failure, clz_tab.o has to be
    in lib/lib.a rather than lib/builtin.o.  The specific issue is that
    libgcc.a comes before lib/builtin.o on vmlinux.o's link command line, so
    its _clz.o is pulled to satisfy __clz_tab, and then when the remainder
    of lib/builtin.o is pulled in to satisfy all the other dependencies, the
    __clz_tab symbols conflict.  By putting clz_tab.o in lib.a, the linker
    can simply avoid pulling it into vmlinux.o when this situation arises.
    
    The definitions of __clz_tab are the same in libgcc.a and in the kernel;
    arguably we could also simply rename the kernel version, but it's
    unlikely the libgcc version will ever change to become incompatible, so
    just using it seems reasonably safe.
    Signed-off-by: default avatarChris Metcalf <cmetcalf@ezchip.com>
    Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    f5948701
Makefile 6.62 KB