I configured and built rust with the extra target: arm-unknown-linux-gnueabihf. The build process used the correct compiler/linker (arm-linux-gnueabihf-g++) but when trying to build a rust program (with --target arm-unknown-linux-gnueabihf) rustc tries to link by passing -marm to cc and fails because cc is the host compiler and does not know how to link arm objects. Since the configure script has already figured out the correct compiler/linker, it would be nice if the built rustc could also use them.