Xen now available in CentOS 7 for ARM64 servers

A little more than a week ago at Linaro Connect SFO15 in Burlingame Jim Perrin of the CentOS project publicly announced the availability of the Xen hypervisor in CentOS 7 for ARM64 (also known as aarch64). Jim and I have been working closely with George Dunlap, maintainer of Xen in CentOS for the x86 architecture, to produce high quality Xen binaries for 64-bit ARM servers. As a result you can setup an ARM64 virtualization host with just a couple of yum commands.
CentOS 7 aarch64 is available here. Installation is trivial: download the live image, try it out, and write it to disk if you like it. You can easily extend the root partition and filesystem to match the size of your disk.
Once you have CentOS 7 up and running on your ARM64 server, you can install Xen and Libvirt with the following commands:

yum install centos-release-xen
yum update
yum install xen libvirt

If you are using AppliedMicro X-Gene, you need to add a Xen command line option to specify which serial to use. This is due to the firmware missing one piece of information. We are working with AppliedMicro to fix the issue as soon as possible. In the meantime you can edit /etc/default/grub and add the following to GRUB_CMDLINE_XEN_DEFAULT:

dtuart=/soc/serial@1c020000

recreate the grub config file:

grub2-mkconfig -o /boot/efi/EFI/centos/grub.cfg

Reboot and you’ll have Xen and Libvirt ready to use! Simple, right? 🙂
If you want to try running a CentOS guest, just download the CentOS 7 live image, unpack it, and write a basic VM config file, using the Dom0 kernel and initramfs. For example:

kernel="/boot/vmlinuz-4.2.0-0.1.centos.el7.aarch64"
ramdisk="/boot/initramfs-4.2.0-0.1.centos.el7.aarch64.img"
memory=512
root="/dev/xvda4"
disk=[ "file:/path/to/CentOS-7-aarch64-rolling.img,xvda,w" ] name = "centos7"
vcpus = 1
extra="console=hvc0"

Use xl to create the guest and connect to its console:

xl create -c config

Rinse and repeat as many times as you like, and you’ll have many little CentOS virtual machines keeping you company.
Xen 4.6 will be released shortly and you can count on us updating the Xen rpm in CentOS 7 shortly after. You’ll be able to install the latest and greatest Xen hypervisor release for ARM64 with a simple yum install.
At Linaro Connect I went further by showing ready to use OpenStack packages for CentOS 7 aarch64. Thanks to Anthony Perard, who produced those rpms, setting up Nova with Xen on ARM64 is just a matter of installing the packages and starting Nova services. Jim promised to have the OpenStack rpms online at centos.org in a couple of weeks. Stay tuned!