There is a buildroot-demos in the GIT repository, which is very cool and can compile the kernel, bootloader, root filesystem, cross-compile tool chain all at once, but the buildroot-demos only supports ARCHs like ARC 750D, ARC 770D, ARC HS38.
It's hoped that the support for the arch of HS48FS would also be added into the builderoot-demos repository.
Thanks!