BR2_riscv=y BR2_TOOLCHAIN_EXTERNAL=y BR2_TOOLCHAIN_EXTERNAL_DOWNLOAD=y BR2_TOOLCHAIN_EXTERNAL_URL="http://autobuild.buildroot.net/toolchains/tarballs/br-riscv64-glibc-2019.05.1.tar.bz2" BR2_TOOLCHAIN_EXTERNAL_GCC_7=y BR2_TOOLCHAIN_EXTERNAL_HEADERS_5_1=y BR2_TOOLCHAIN_EXTERNAL_CUSTOM_GLIBC=y BR2_TOOLCHAIN_EXTERNAL_CXX=y