U-boot compile for DE10-NANO under Windows10 via Cygwin: unable to execute binary file?


On several post I read that the job cannot is not possible, other claim it is.
There is a document by OGUS METEER (Bitlog.IT) describing the job for Linux,
I am trying to follow this document but without success until now.
This post is a bit long, but i tried to describe my steps in much detail.

  1. Quartus + Qsys part = no problem.
  2. Compile the preloader : be sure to execute “export PATH=/bin:$PATH” otherwise tar gets confused in different versions (help by @JanKonecny)
  3. Compile U-Boot

untar compiler:
tar -xvf gcc-linaro-6.3.1-2017.05-x86_64_arm-linux-gnueabihf.tar.xz (ok)

define exported CROSS_COMPILE:
export CROSS_COMPILE=$PWD/gcc-linaro-6.3.1-2017.05-x86_64_arm-linux-gnueabihf/bin/arm-linux-gnueabihf-
double check:
$ cd /cygdrive/c/FpgaQsysProjects/DE10_NANO_SoC_GHRD/software/gcc-linaro-6.3.1-2017.05-x86_64_arm-linux-gnueabihf/bin/
$ dir
arm-linux-gnueabihf-addr2line arm-linux-gnueabihf-cpp arm-linux-gnueabihf-gcc-6.3.1 arm-linux-gnueabihf-gcov-dump arm-linux-gnueabihf-ld arm-linux-gnueabihf-objdump arm-linux-gnueabihf-strip
arm-linux-gnueabihf-ar arm-linux-gnueabihf-dwp arm-linux-gnueabihf-gcc-ar arm-linux-gnueabihf-gcov-tool arm-linux-gnueabihf-ld.bfd arm-linux-gnueabihf-ranlib gdbserver
arm-linux-gnueabihf-as arm-linux-gnueabihf-elfedit arm-linux-gnueabihf-gcc-nm arm-linux-gnueabihf-gdb arm-linux-gnueabihf-ld.gold arm-linux-gnueabihf-readelf runtest
arm-linux-gnueabihf-c++ arm-linux-gnueabihf-g++ arm-linux-gnueabihf-gcc-ranlib arm-linux-gnueabihf-gfortran arm-linux-gnueabihf-nm arm-linux-gnueabihf-size
arm-linux-gnueabihf-c++filt arm-linux-gnueabihf-gcc arm-linux-gnueabihf-gcov arm-linux-gnueabihf-gprof arm-linux-gnueabihf-objcopy arm-linux-gnueabihf-strings
=> so I am very sure that $CROSS_COMPILE points to the right directory containing gcc compiler.

get U-Boot:
$ git clone https://github.com/altera-opensource/u-boot-socfpga.git
=> this line fails “error certificate varify locations”
possible but bold solution: $ git config --system http.sslverify false
$ git clone https://github.com/altera-opensource/u-boot-socfpga.git (ok)
$ cd u-boot-socfpga (ok)
$ git tag -l rel_socfpga* (ok)
$ git checkout rel_socfpga_v2013.01.01_17.08.01_pr (ok)

$ make mrproper
/cygdrive/c/FpgaQsysProjects/DE10_NANO_SoC_GHRD/software/gcc-linaro-6.3.1-2017.05-x86_64_arm-linux-gnueabihf/bin/arm-linux-gnueabihf-gcc: /cygdrive/c/FpgaQsysProjects/DE10_NANO_SoC_GHRD/software/
gcc-linaro-6.3.1-2017.05-x86_64_arm-linux-gnueabihf/bin/arm-linux-gnueabihf-gcc: unable to execute binary file ??
unable to remove SPL, SPL is a directory.

!=> My question: why is cygwin unable to execute the binary file & why is make unable to remove SPL? Is this issue Cygwin related or did i forget someting (my experience in Linux is very limited).

make socfpga_cyclone5_config (ok)

!=> same error, unable to execute binary file, how can this be solved?

Best Regards,