Comment 12 for bug 1659618

I was able to apply this patch and build kexec-tools on Xenial. Please see this link for details: https://pastebin.ubuntu.com/23950298/

[TESTING]

== Y kernel for X series with kexec support ==
I had to build a Yakkety kernel for Xenial series with KEXEC enabled.
ubuntu@test:~$ uname -a
Linux test 4.8.0-38-generic #40ubuntu1 SMP Tue Feb 7 21:26:52 UTC 2017 aarch64 aarch64 aarch64 GNU/Linux

== kexec-tools with patches to enable ARM64 support ==

ubuntu@test:~$ dpkg -l | grep kexec-tools
ii kexec-tools 1:2.0.10-1ubuntu2.1 arm64 tools to support fast kexec reboots
ubuntu@test:~$

== Load kexec kernel and initiate kexec ==
ubuntu@test:~$ sudo kexec -l /boot/vmlinuz-4.8.0-38-generic --initrd=/boot/initrd.img-4.8.0-38-generic --append="root=UUID=6ef62239-dad9-409b-a3ab-1847e44aa779 ro vt.handoff=7"
ubuntu@test:~$ sudo kexec -e

== Successful live boot of kexec kernel ==
Ubuntu 16.04.1 LTS test ttyAMA0

test login: [ 85.371808] kexec_core: Starting new kernel
[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Linux version 4.8.0-38-generic (manjo@tangerine) (gcc version 5.3.1 20160413 (Ubuntu/Linaro 5.3.1-14ubuntu2) ) #40ubuntu1 SMP Tue Feb 7 21:26:52 UTC 2017 (Ubuntu 4.8.0-38.40ubuntu1-generic 4.8.17)
[ 0.000000] Boot CPU: AArch64 Processor [510f8000]
[ 0.000000] efi: Getting EFI parameters from FDT:
[ 0.000000] efi: EFI v2.50 by EDK II
[ 0.000000] efi: SMBIOS=0x5bdb0000 SMBIOS 3.0=0x58660000 PROP=0x5f714518 ACPI=0x58690000 ACPI 2.0=0x58690014
[ 0.000000] No NUMA configuration found