The code accessing the floating point control/status register, namely #define __cfc1(__fcsr) __asm __volatile("cfc1 %0, $31" : "=r" (__fcsr) does not compile with mips16. This changed the makefile to pass -mno-mips16 to avoid the following compiler error: mips-mti-elf fails with "Error: unrecognized opcode `cfc1 $3,$31'" --- newlib-4.1.0/newlib/libm/machine/mips/Makefile.in.orig 2021-11-12 11:49:11.691337941 +0100 +++ newlib-4.1.0/newlib/libm/machine/mips/Makefile.in 2021-11-12 11:48:21.181600000 +0100 @@ -349,7 +349,7 @@ lib_a-feupdateenv.obj: feupdateenv.c $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-feupdateenv.obj `if test -f 'feupdateenv.c'; then $(CYGPATH_W) 'feupdateenv.c'; else $(CYGPATH_W) '$(srcdir)/feupdateenv.c'; fi` lib_a-fenv.o: fenv.c - $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-fenv.o `test -f 'fenv.c' || echo '$(srcdir)/'`fenv.c + $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -mno-mips16 -c -o lib_a-fenv.o `test -f 'fenv.c' || echo '$(srcdir)/'`fenv.c lib_a-fenv.obj: fenv.c $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-fenv.obj `if test -f 'fenv.c'; then $(CYGPATH_W) 'fenv.c'; else $(CYGPATH_W) '$(srcdir)/fenv.c'; fi`