http://gcc.gnu.org/ml/gcc-patches/2008-10/msg00269.html On glibc the libc.so carries a copy of the math function copysignl() but on uClibc math functions like copysignl() live in libm. Since libgcc_s contains unresolved symbols, any attempt to link against libgcc_s without explicitely specifying -lm fails, resulting in a broken bootstrap of the compiler. Forward port to gcc 4.5.1 by Gustavo Zacarias diff -Nura gcc-4.5.1.orig/gcc/config/t-slibgcc-elf-ver gcc-4.5.1/gcc/config/t-slibgcc-elf-ver --- gcc-4.5.1.orig/gcc/config/t-slibgcc-elf-ver 2010-11-03 14:35:08.644904042 -0300 +++ gcc-4.5.1/gcc/config/t-slibgcc-elf-ver 2010-11-03 14:35:56.332904024 -0300 @@ -27,7 +27,7 @@ SHLIB_OBJS = @shlib_objs@ SHLIB_DIR = @multilib_dir@ SHLIB_SLIBDIR_QUAL = @shlib_slibdir_qual@ -SHLIB_LC = -lc +SHLIB_LC = @libgcc_libm@ -lc SHLIB_MAKE_SOLINK = $(LN_S) $(SHLIB_SONAME) $(SHLIB_DIR)/$(SHLIB_SOLINK) SHLIB_INSTALL_SOLINK = $(LN_S) $(SHLIB_SONAME) \ $$(DESTDIR)$$(slibdir)$(SHLIB_SLIBDIR_QUAL)/$(SHLIB_SOLINK) diff -Nura gcc-4.5.1.orig/libgcc/Makefile.in gcc-4.5.1/libgcc/Makefile.in --- gcc-4.5.1.orig/libgcc/Makefile.in 2010-11-03 14:32:44.272904042 -0300 +++ gcc-4.5.1/libgcc/Makefile.in 2010-11-03 14:37:03.893904042 -0300 @@ -39,6 +39,7 @@ decimal_float = @decimal_float@ enable_decimal_float = @enable_decimal_float@ fixed_point = @fixed_point@ +LIBGCC_LIBM = @LIBGCC_LIBM@ host_noncanonical = @host_noncanonical@ @@ -798,9 +799,10 @@ @multilib_dir@,$(MULTIDIR),$(subst \ @shlib_objs@,$(objects),$(subst \ @shlib_base_name@,libgcc_s,$(subst \ + @libgcc_libm@,$(LIBGCC_LIBM),$(subst \ @shlib_map_file@,$(mapfile),$(subst \ @shlib_slibdir_qual@,$(MULTIOSSUBDIR),$(subst \ - @shlib_slibdir@,$(shlib_slibdir),$(SHLIB_LINK)))))))) + @shlib_slibdir@,$(shlib_slibdir),$(SHLIB_LINK))))))))) libunwind$(SHLIB_EXT): $(libunwind-s-objects) $(extra-parts) # @multilib_flags@ is still needed because this may use diff -Nura gcc-4.5.1.orig/libgcc/configure gcc-4.5.1/libgcc/configure --- gcc-4.5.1.orig/libgcc/configure 2010-11-03 14:32:44.283904042 -0300 +++ gcc-4.5.1/libgcc/configure 2010-11-03 14:39:48.685904042 -0300 @@ -557,6 +557,7 @@ extra_parts tmake_file set_use_emutls +LIBGCC_LIBM set_have_cc_tls vis_hide fixed_point @@ -3847,6 +3848,37 @@ set_use_emutls="-DUSE_EMUTLS" fi +# On powerpc libgcc_s references copysignl which is a libm function but +# glibc apparently also provides it via libc as opposed to uClibc where +# it lives in libm. +echo "$as_me:$LINENO: checking for library containing copysignl" >&5 +echo $ECHO_N "checking for library containing copysignl... $ECHO_C" >&6 +if test "${libgcc_cv_copysignl_lib+set}" = set; then + echo $ECHO_N "(cached) $ECHO_C" >&6 +else + + echo '#include ' > conftest.c + echo 'int the_libc = __UCLIBC__ + __powerpc__;' >> conftest.c + libgcc_cv_copysignl_lib="-lc" + if { ac_try='${CC-cc} -S conftest.c -o conftest.s 1>&5' + { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5 + (eval $ac_try) 2>&5 + ac_status=$? + echo "$as_me:$LINENO: \$? = $ac_status" >&5 + (exit $ac_status); }; } + then + libgcc_cv_copysignl_lib="-lm" + fi + rm -f conftest.* + +fi +echo "$as_me:$LINENO: result: $libgcc_cv_copysignl_lib" >&5 +echo "${ECHO_T}$libgcc_cv_copysignl_lib" >&6 + +case /${libgcc_cv_copysignl_lib}/ in + /-lm/) LIBGCC_LIBM="$LIBGCC_LIBM -lm" ;; + *) LIBGCC_LIBM= ;; +esac # Conditionalize the makefile for this target machine. tmake_file_= diff -Nura gcc-4.5.1.orig/libgcc/configure.ac gcc-4.5.1/libgcc/configure.ac --- gcc-4.5.1.orig/libgcc/configure.ac 2010-11-03 14:32:44.735904042 -0300 +++ gcc-4.5.1/libgcc/configure.ac 2010-11-03 14:42:11.278904045 -0300 @@ -238,6 +238,27 @@ fi AC_SUBST(set_have_cc_tls) +# On powerpc libgcc_s references copysignl which is a libm function but +# glibc apparently also provides it via libc as opposed to uClibc where +# it lives in libm. +AC_CACHE_CHECK + libgcc_cv_copysignl_lib, + echo '#include ' > conftest.c + echo 'int the_libc = __UCLIBC__ + __powerpc__;' >> conftest.c + libgcc_cv_copysignl_lib="-lc" + if AC_TRY_COMMAND(${CC-cc} -S conftest.c -o conftest.s 1>&AS_MESSAGE_LOG_FD) + then + libgcc_cv_copysignl_lib="-lm" + fi + rm -f conftest.* + ]) + +case /${libgcc_cv_copysignl_lib}/ in + /-lm/) LIBGCC_LIBM="$LIBGCC_LIBM -lm" ;; + *) LIBGCC_LIBM= ;; +esac +AC_SUBST(LIBGCC_LIBM) + # See if we have emulated thread-local storage. GCC_CHECK_EMUTLS set_use_emutls=