Scripts to build binutils, gcc (w/o libc) and gdb for xtensa.
$ # check config file (vars BINUTILS, GCC, GDB, PARALLEL)
$ ./prepare.sh target-variant
$ ./fixup-gdb.sh # optional, for compatibility with QEMU
$ ./build.sh target-variant

You either need unpacked/overlayed binutils, gcc and gdb in the
current directory, or archives thereof (unpacked and overlayed
by prepare.sh).

Further steps to build uClibc, binutils, and gcc for linux.
$ # check config file (vars LINUX and UCLIBC) and config.uClibc
$ ./build-linux.sh target-variant

You need unpacked linux and uClibc sources in the current
directory.