Version 4.17 of the Xen project’s eponymous hypervisor has debuted, bringing with it the first look at Hyperlaunch capabilities that allow the creation of multipole VMs on startup.
When Xen goes to work today, it creates Dom0 – a privileged domain that has to run before the DomU unprivileged domains that contain virtual machines can get to work.
In 2018, Xen developers started work to change that – in part because Dom0 takes a while to get going on small devices, leading some developers to look at alternative hypervisors. Makers of small devices like virtualization because the isolation it affords improves the security of their machines.
In fields like automotive, hypervisors are also appreciated as they allow manufacturers to reduce the number of devices in a vehicle. If one computer can offer sufficient power, and the isolation required to stop an entertainment system interfering with self-driving software, the weight and cost of cars goes down.
Hyperlaunch makes that sort of scenario possible by allowing the definition of VM fleets that boot when a computer powers up. You can even pin hardware resources to different VMs.
Hyperlaunch gets Xen closer to the functionality of some niche hypervisors and makes it friendlier to unikernels. It also allows developers to choose different modes of operation: it’s possible to work much as Dom0 does today, or to configure systems to boot multiple VMs all at once with known privileges and resources, or to boot and let VMs hunt for resources their images may not have pre-defined.
Other additions to this cut of the project that Xen’s developers feel are noteworthy include:
- Integration with the MISRA-C guidelines for coding safely in C on embedded systems;
- Static configuration options for Arm that mean VMs are allocated only the resources they’ve requested at boot time;
- A tech preview implementation of VirtIO on Arm CPU;
- Support for x86 VMs with 12 terabytes of memory.
Much of the above reflects the Project’s decision to emphasize the embedded market rather than server virtualization. Citrix dropped the ball in the latter market. Xen was for a time Amazon Web Services’ hypervisor of choice, but the cloud giant revealed a move to a custom cut of KVM in 2017.
Xen 4.17 is yours for the downloading here. ®