I did it: [https://github.com/ponyatov/nims/blob/260926-884b/mips/src/nim.cfg](https://github.com/ponyatov/nims/blob/260926-884b/mips/src/nim.cfg)
The magic with C++ compiling was the use of gcc _as a linker_ : --os:linux --cpu:mipsel --cc:gcc gcc.exe:"mipsel-openwrt-linux-musl-gcc" gcc.linkerexe:"mipsel-openwrt-linux-musl-gcc" gcc.cpp.exe:"mipsel-openwrt-linux-musl-g++" gcc.cpp.linkerexe:"mipsel-openwrt-linux-musl-gcc" --listCmd passL:"-L/home/dpon/ICBLINK/openwrt-18.06.4/staging_dir/target-mipsel_24kc_musl/usr/lib" passL:"-L/home/dpon/ICBLINK/openwrt-18.06.4/staging_dir/toolchain-mipsel_24kc_gcc-7.3.0_musl/lib/gcc/mipsel-openwrt-linux-musl/7.3.0" passL:"-luClibc++" --debugger:native Run PS: and don't forget to enable CONFIG_PACKAGE_uclibcxx=y in OpenWrt .config