Booting Linux kernel under UEFI hangs immediately after download

[langlorx]

I am attempting to use iPXE to load the installers for various Linux Distributions onto UEFI enabled servers. The server's are able to boot correctly in BIOS mode, but fail when UEFI is enabled. When they fail, it is immediately after successfully downloading both the kernel and initrd. Nothing is printed after the ok message for the ftp download of the initrd and it hangs forever. This happens whether attempting to boot the installer for Ubuntu 16.04, Fedora 24, or CentOS 7.2.

This same setup works correctly when attempting to booth these same installers using the UEFI mode in a KVM/Qemu virtual machine.

Also, experiments with using PXE Grub on real hardware to boot the same kernels have been successful, but it relies on TFTP which is much slower.

Here's my script for installing Ubuntu 16.04:

#!ipxe
kernel ftp://server/pxeboot/ubuntu-installer/amd64/linux initrd=initramfs
initrd --name initramfs ftp://server/pxeboot/ubuntu-installer/amd64/initrd.gz
boot