GRUB2 currently uses [[http://wiki.osdev.org/Programmable_Interval_Timer|PIT]] to calculate time. This fails on Generation 2 Hyper-V virtual machines and any request for a file on a tftp server made by grubnetx64.efi will fail instantly due to timeout.

For your convenience you can {{:grubnetx64.efi.gz|download an already patched version here}}

====== Compile grub with EFI SetTimer() ======

Install grub2-efi dependencies and build the package:

  sudo apt-get build-dep grub-efi-amd64
  sudo apt-get install unzip
  mkdir -p $HOME/build-grub && pushd $HOME/build-grub
  apt-get source grub-efi-amd64
  cd grub2-*
  wget "http://savannah.gnu.org/bugs/download.php?file_id=32245" -O grub2.zip
  unzip grub2.zip
  patch -p2 < grub_hyperv_gen2.patch
  dpkg-buildpackage -b


Your grubnetx.efi will be in:

  debian/grub2-images/*/grubnetx64.efi