if 'RISCV' not in config.root.targets:
config.unsupported = True
flags = '--target=riscv64 -nostdlib -ffreestanding -Wl,--emit-relocs'
config.substitutions.insert(0, ('%cflags', f'%cflags {flags}'))
config.substitutions.insert(0, ('%cxxflags', f'%cxxflags {flags}'))