Xen is being used in production by many folks, but are they really using the upstream code? If not what are they using? At least SUSE's supported delta for the Linux kernel consists of 116 patches totaling 353,770 lines of code. Debian has 43 patches for a delta of about 1693 lines of code. What is this delta and how do we shrink it? I will give an overview of the supported Linux kernel delta for Xen at SUSE and Debian with upstream but also layout a proposed roadmap of addressing the delta in collaboration with different teams in the Xen community.