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: Chris Metcalf <[email protected]> --- I have this in the tile tree for linux-next since it broke tilepro, but perhaps it makes more sense for it to get pushed through Andrew's tree or somewhere else? lib/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/Makefile b/lib/Makefile index 7f1de26613d2..8487893b4deb 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -153,7 +153,7 @@ obj-$(CONFIG_GLOB) += glob.o obj-$(CONFIG_MPILIB) += mpi/ obj-$(CONFIG_SIGNATURE) += digsig.o -obj-$(CONFIG_CLZ_TAB) += clz_tab.o +lib-$(CONFIG_CLZ_TAB) += clz_tab.o obj-$(CONFIG_DDR) += jedec_ddr_data.o -- 2.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
