unable to cross compile for target avr

[Klaus Rudolph <lts-rudolph@xxxxxx>]

I try to get a avr toolchain up and running.

I have the following Makefile

GCC_VER=8.3.0
PRE_PREFIX=/opt
LINUX=linux-gnu
AVR=avr

unpack:
    mkdir unpack
    ( cd unpack; \
        tar xf ../mpc* ;\
        tar xf ../mpfr* ; \
        tar xf ../gmp* ; \
        tar xf ../gcc* ; \
        tar xf ../binutils* ; \
        cd gcc* ;\
        mv ../mpc* ./mpc ;\
        mv ../mpfr* ./mpfr ; \
        mv ../gmp* ./gmp ; \
        )



avrbinutils:
    ( cd unpack/binutils* ; \
        mkdir build_binutils_avr ; \
        cd build_binutils_avr ; \
        ../configure --prefix=$(PRE_PREFIX)/$(AVR)_$(GCC_VER) 
--target=avr --disable-nls --enable-gold --enable-plugins; \
        make -j8 ; \
        sudo make install \
        )

avrgcc:
    ( cd unpack/gcc* ; \
        mkdir build_gccavr; \
        cd build_gccavr ; \
        ../configure --prefix=$(PRE_PREFIX)/$(AVR)_$(GCC_VER) 
--target=avr --enable-languages=c,c++ --enable-lto --disable-nls 
--disable-libssp; \
        make  ; \
        )

So I do:
make unpack
make avrbinutils
make avrgcc

During compiling gcc for target avr I got:

make[3]: Entering directory 
'/home/krud/git_my_checkout/first/own_components/gcc_install/unpack/gcc-8.3.0/build_gccavr/gcc'
TARGET_CPU_DEFAULT="" \
HEADERS="auto-host.h ansidecl.h" DEFINES="" \
/bin/sh ../../gcc/mkconfig.sh config.h
TARGET_CPU_DEFAULT="" \
HEADERS="options.h insn-constants.h config/elfos.h config/avr/elf.h 
config/avr/avr-arch.h config/avr/avr.h config/avr/specs.h 
config/dbxelf.h config/avr/avr-stdint.h config/avr/avrlibc.h 
config/initfini-array.h defaults.h" DEFINES="LIBC_GLIBC=1 LIBC_UCLIBC=2 
LIBC_BIONIC=3 LIBC_MUSL=4 WITH_AVRLIBC" \
/bin/sh ../../gcc/mkconfig.sh tm.h
TARGET_CPU_DEFAULT="" \
HEADERS="config/avr/avr-protos.h tm-preds.h" DEFINES="" \
/bin/sh ../../gcc/mkconfig.sh tm_p.h
TARGET_CPU_DEFAULT="" \
HEADERS="auto-host.h ansidecl.h" DEFINES="" \
/bin/sh ../../gcc/mkconfig.sh bconfig.h
g++ -c   -g -O2 -DIN_GCC  -DCROSS_DIRECTORY_STRUCTURE   -fno-exceptions 
-fno-rtti -fasynchronous-unwind-tables -W -Wall -Wno-narrowing 
-Wwrite-strings -Wcast-qual -Wmissing-format-attribute 
-Woverloaded-virtual -pedantic -Wno-long-long -Wno-variadic-macros 
-Wno-overlength-strings   -DHAVE_CONFIG_H -DGENERATOR_FILE -fno-PIE -I. 
-Ibuild -I../../gcc -I../../gcc/build -I../../gcc/../include 
-I../../gcc/../libcpp/include  \
	-o build/genmodes.o ../../gcc/genmodes.c
/opt/avr_8.3.0/avr/bin/as: unrecognized option '--64'
make[3]: *** [Makefile:2669: build/genmodes.o] Error 1
make[3]: Leaving directory 
'/home/krud/git_my_checkout/first/own_components/gcc_install/unpack/gcc-8.3.0/build_gccavr/gcc'
make[2]: *** [Makefile:4254: all-gcc] Error 2
make[2]: Leaving directory 
'/home/krud/git_my_checkout/first/own_components/gcc_install/unpack/gcc-8.3.0/build_gccavr'
make[1]: *** [Makefile:889: all] Error 2
make[1]: Leaving directory 
'/home/krud/git_my_checkout/first/own_components/gcc_install/unpack/gcc-8.3.0/build_gccavr'
make: *** [Makefile.gcc8.3.0:65: avrgcc] Error 2

Looks very crazy, because it calls g++ from host and got an error from 
avr-as if I did not interpret the things wrong here.

System is Fedora 28
gcc (GCC) 8.3.1 20190223 (Red Hat 8.3.1-2)


Can anyone help to get avr toolchain compiled?


Thanks
 Klaus