def do_configure(d):
    import json
    import configparser

    # toml is rather similar to standard ini like format except it likes values
    # that look more JSON like. So for our purposes simply escaping all values
    # as JSON seem to work fine.

    e = lambda s: json.dumps(s)

    config = configparser.RawConfigParser()

    # [target.ARCH-poky-linux]
    host_section = "target.{}".format(d.getVar('RUST_HOST_SYS'))
    config.add_section(host_section)

    llvm_config_target = d.expand("${RUST_ALTERNATE_EXE_PATH}")
    llvm_config_build = d.expand("${RUST_ALTERNATE_EXE_PATH_NATIVE}")
    config.set(host_section, "llvm-config", e(llvm_config_target))

    config.set(host_section, "cxx", e(d.expand("${RUST_TARGET_CXX}")))
    config.set(host_section, "cc", e(d.expand("${RUST_TARGET_CC}")))
    config.set(host_section, "linker", e(d.expand("${RUST_TARGET_CCLD}")))
    if "musl" in host_section:
        config.set(host_section, "musl-root", e(d.expand("${STAGING_DIR_HOST}${exec_prefix}")))

    # If we don't do this rust-native will compile it's own llvm for BUILD.
    # [target.${BUILD_ARCH}-unknown-linux-gnu]
    build_section = "target.{}".format(d.getVar('RUST_BUILD_SYS'))
    if build_section != host_section:
        config.add_section(build_section)

        config.set(build_section, "llvm-config", e(llvm_config_build))

        config.set(build_section, "cxx", e(d.expand("${RUST_BUILD_CXX}")))
        config.set(build_section, "cc", e(d.expand("${RUST_BUILD_CC}")))
        config.set(build_section, "linker", e(d.expand("${RUST_BUILD_CCLD}")))

    target_section = "target.{}".format(d.getVar('RUST_TARGET_SYS'))
    if target_section != host_section and target_section != build_section:
        config.add_section(target_section)

        config.set(target_section, "llvm-config", e(llvm_config_target))

        config.set(target_section, "cxx", e(d.expand("${RUST_TARGET_CXX}")))
        config.set(target_section, "cc", e(d.expand("${RUST_TARGET_CC}")))
        config.set(target_section, "linker", e(d.expand("${RUST_TARGET_CCLD}")))

    # [llvm]
    config.add_section("llvm")
    config.set("llvm", "static-libstdcpp", e(False))
    if "llvm" in (d.getVar('TC_CXX_RUNTIME') or ""):
        config.set("llvm", "use-libcxx", e(True))

    # [rust]
    config.add_section("rust")
    config.set("rust", "rpath", e(True))
    config.set("rust", "remap-debuginfo", e(True))
    config.set("rust", "channel", e(d.expand("${RUST_CHANNEL}")))

    # Whether or not to optimize the compiler and standard library
    config.set("rust", "optimize", e(True))

    # Emits extraneous output from tests to ensure that failures of the test
    # harness are debuggable just from logfiles
    config.set("rust", "verbose-tests", e(True))

    # [build]
    config.add_section("build")
    config.set("build", "submodules", e(False))
    config.set("build", "docs", e(False))

    rustc = d.getVar('RUSTC_BOOTSTRAP')
    config.set("build", "rustc", e(rustc))

    cargo = d.getVar('CARGO_BOOTSTRAP')
    config.set("build", "cargo", e(cargo))

    config.set("build", "vendor", e(True))

    config.set("build", "target", e([d.getVar("RUST_TARGET_SYS")]))

    config.set("build", "host", e([d.getVar("RUST_HOST_SYS")]))

    # We can't use BUILD_SYS since that is something the rust snapshot knows
    # nothing about when trying to build some stage0 tools (like fabricate)
    config.set("build", "build", e(d.getVar("RUST_BUILD_SYS")))

    # [install]
    config.add_section("install")
    # ./x.py install doesn't have any notion of "destdir"
    # but we can prepend ${D} to all the directories instead
    config.set("install", "prefix",  e(d.getVar("D") + d.getVar("prefix")))
    config.set("install", "bindir",  e(d.getVar("D") + d.getVar("bindir")))
    config.set("install", "libdir",  e(d.getVar("D") + d.getVar("libdir")))
    config.set("install", "datadir", e(d.getVar("D") + d.getVar("datadir")))
    config.set("install", "mandir",  e(d.getVar("D") + d.getVar("mandir")))
    config.set("install", "sysconfdir",  e(d.getVar("D") + d.getVar("sysconfdir")))

    with open("config.toml", "w") as f:
        f.write('change-id = 116881\n\n')
        config.write(f)

    # set up ${WORKDIR}/cargo_home
    bb.build.exec_func("setup_cargo_environment", d)

do_configure(d)