These tarballs are temporary. They are being used to bootstrap openjdk8 for the RC3 release. In the future, we will be using GCC 6.5.0 to bootstrap openjdk7 for supported architectures, and may use alternate means to bootstrap for unsupported architectures. They were produced using the 'user/openjdk8/maintain' script on an RC2 installation with 'curl', 'libarchive-tools', and 'xz'.