Referencing the expanding the thread I started several months ago
      entitled
      "Xen 4.12.0-rc Hangs Around masked ExtINT on CPU#", I installed a
      fresh hard
      drive on my Supermicro Atom server class unit and did the
      following:
    per:
https://wiki.xen.org/wiki/Xen_Project_Beginners_Guide#Download_and_Burn_the_Debian_Installer_CD
      
      downloaded:
http://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-9.9.0-amd64-netinst.iso
      burned CD
      
      on boot had to select UEFI ASUS install, the regular ASUS did not
      work.
      console was blank,
      screen attached has graphical image light blue, selected graphical
      install
      proceeded with install.
      Reboot.
      did NOT perform the suggested: apt-get install
      firmware-linux-nonfree
      
      performed:
          apt-get install xen-system-amd64
      restart.
      startup hangs.
    So, I had in November of 2016 installed Debian on this then-new
      server
      using:
    
         debian-8.6.0-amd64-netinst.iso
    and then installed Xen using the above instructions.
    What I propose to do now is duplicate my steps of November 2016.
    If I succeed in launching DOM0 as I did in November/December
      2016,
      then we'll know this is a software issue.  If I fail, then I'd
      conclude
      there is a hardware problem.  Recall, though I can install a
      standard
      build of Debian 9.9 and Gentoo and the kernels load, it's only
      when
      I have a Xen modified kernel that the boot-up hangs.
    I'm not familiar with Debian other than I have easily installed
      it
      before.  What would help me are some pointers to make sure
      the Debian 8.6.0 does not go into auto-update mode and to identify
      and select
      the Xen packages which were the high watermark in November 2016.