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. diff -rdup gcc-4.4.0.old/gcc/config/t-slibgcc-elf-ver gcc-4.4.0/gcc/config/t-slibgcc-elf-ver --- gcc-4.4.0.old/gcc/config/t-slibgcc-elf-ver 2005-10-31 18:03:08.000000000 +0100 +++ gcc-4.4.0/gcc/config/t-slibgcc-elf-ver 2008-10-07 19:28:13.000000000 +0200 @@ -9,7 +9,7 @@ SHLIB_MAP = @shlib_map_file@ 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 -rdup gcc-4.4.0.old/libgcc/configure gcc-4.4.0/libgcc/configure --- gcc-4.4.0.old/libgcc/configure 2008-07-17 10:40:53.000000000 +0200 +++ gcc-4.4.0/libgcc/configure 2008-10-07 19:40:48.000000000 +0200 @@ -272,7 +272,7 @@ PACKAGE_STRING='GNU C Runtime Library 1. PACKAGE_BUGREPORT='' ac_unique_file="static-object.mk" -ac_subst_vars='SHELL PATH_SEPARATOR PACKAGE_NAME PACKAGE_TARNAME PACKAGE_VERSION PACKAGE_STRING PACKAGE_BUGREPORT exec_prefix prefix program_transform_name bindir sbindir libexecdir datadir sysconfdir sharedstatedir localstatedir libdir includedir oldincludedir infodir mandir build_alias host_alias target_alias DEFS ECHO_C ECHO_N ECHO_T LIBS libgcc_topdir enable_shared slibdir INSTALL_PROGRAM INSTALL_SCRIPT INSTALL_DATA AWK build build_cpu build_vendor build_os host host_cpu host_vendor host_os host_noncanonical build_libsubdir build_subdir host_subdir target_subdir AR ac_ct_AR LIPO ac_ct_LIPO NM ac_ct_NM RANLIB ac_ct_RANLIB STRIP ac_ct_STRIP LN_S CC CFLAGS LDFLAGS CPPFLAGS ac_ct_CC EXEEXT OBJEXT CPP decimal_float enable_decimal_float fixed_point vis_hide set_have_cc_tls tmake_file extra_parts asm_hidden_op LIBOBJS LTLIBOBJS' +ac_subst_vars='SHELL PATH_SEPARATOR PACKAGE_NAME PACKAGE_TARNAME PACKAGE_VERSION PACKAGE_STRING PACKAGE_BUGREPORT exec_prefix prefix program_transform_name bindir sbindir libexecdir datadir sysconfdir sharedstatedir localstatedir libdir includedir oldincludedir infodir mandir build_alias host_alias target_alias DEFS ECHO_C ECHO_N ECHO_T LIBS libgcc_topdir enable_shared slibdir INSTALL_PROGRAM INSTALL_SCRIPT INSTALL_DATA AWK build build_cpu build_vendor build_os host host_cpu host_vendor host_os host_noncanonical build_libsubdir build_subdir host_subdir target_subdir AR ac_ct_AR LIPO ac_ct_LIPO NM ac_ct_NM RANLIB ac_ct_RANLIB STRIP ac_ct_STRIP LN_S CC CFLAGS LDFLAGS CPPFLAGS ac_ct_CC EXEEXT OBJEXT CPP decimal_float enable_decimal_float fixed_point vis_hide set_have_cc_tls LIBGCC_LIBM tmake_file extra_parts asm_hidden_op LIBOBJS LTLIBOBJS' ac_subst_files='' ac_pwd=`pwd` @@ -3522,6 +3522,39 @@ if test "$enable_tls $gcc_cv_have_cc_tls fi +# On powerpc libgcc_s references copysignl which is a libm function but +# glibc apparently also provides it via libc as opposed to uClibc where +# it lives in libm. +echo "$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_= for f in ${tmake_file} @@ -4242,6 +4275,7 @@ s,@enable_decimal_float@,$enable_decimal s,@fixed_point@,$fixed_point,;t t s,@vis_hide@,$vis_hide,;t t s,@set_have_cc_tls@,$set_have_cc_tls,;t t +s,@LIBGCC_LIBM@,$LIBGCC_LIBM,;t t s,@tmake_file@,$tmake_file,;t t s,@extra_parts@,$extra_parts,;t t s,@asm_hidden_op@,$asm_hidden_op,;t t diff -rdup gcc-4.4.0.old/libgcc/configure.ac gcc-4.4.0/libgcc/configure.ac --- gcc-4.4.0.old/libgcc/configure.ac 2008-07-17 10:40:53.000000000 +0200 +++ gcc-4.4.0/libgcc/configure.ac 2008-10-07 19:34:48.000000000 +0200 @@ -203,6 +203,27 @@ if test "$enable_tls $gcc_cv_have_cc_tls fi AC_SUBST(set_have_cc_tls) +# On powerpc libgcc_s references copysignl which is a libm function but +# glibc apparently also provides it via libc as opposed to uClibc where +# it lives in libm. +AC_CACHE_CHECK + libgcc_cv_copysignl_lib, + echo '#include ' > conftest.c + echo 'int the_libc = __UCLIBC__ + __powerpc__;' >> conftest.c + libgcc_cv_copysignl_lib="-lc" + if AC_TRY_COMMAND(${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) + # Conditionalize the makefile for this target machine. tmake_file_= for f in ${tmake_file} diff -rdup gcc-4.4.0.old/libgcc/Makefile.in gcc-4.4.0/libgcc/Makefile.in --- gcc-4.4.0.old/libgcc/Makefile.in 2008-07-17 10:40:53.000000000 +0200 +++ gcc-4.4.0/libgcc/Makefile.in 2008-10-07 19:28:13.000000000 +0200 @@ -40,6 +40,7 @@ enable_shared = @enable_shared@ decimal_float = @decimal_float@ enable_decimal_float = @enable_decimal_float@ fixed_point = @fixed_point@ +LIBGCC_LIBM = @LIBGCC_LIBM@ host_noncanonical = @host_noncanonical@ @@ -786,9 +787,10 @@ libgcc_s$(SHLIB_EXT): $(libgcc-s-objects @multilib_dir@,$(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