Unikraft allows developers to build unikernels targeted at specific applications easily. Since Unikraft was announced, Arm has been actively involved to enable it on arm64 kvm platform. In this presentation I intend to share: 1) Features status on arm64, kvm platform(merged and under review) 2) Scalability: multi-thread, SMP support 3) Todo list I will also show some demos on Arm64 among them: 1) 2 veth NIC tx/rx using virtio-mmio bus 2) a lightweight web server

1. 1 Confidential Restricted to Arm Board and Executives © 2019 Arm
When Unikraft Meets Arm64
Jia He, Arm
2019 July
Xen summit 2019 Chicago

2. Agenda
• Introduction to Unikraft
• Status of Unikraft on arm64
• Scalability enhancement (arm64, kvm plat)
• Future plan
• Demo

3. What are Unikernels
• “Unikernels are specialized, single-address-space machine
images constructed by using library operating systems” – wiki
page
• Concepts
• Everything is a library
• One image: single application + minimalistic OS
• Non-preemptive scheduler
• One process
• One address space

4. What are Unikernels
• Pros
• No HEAVY Operating System
• Function call instead of system call
• High deterministic performance
• Contains only needed libraries
• Tiny footprint
• Small attack surface
• Fast boot
• Cons
• Unable to re-use existing device drivers in OS
• Debuggability
• Pros vs Cons • Use cases
• Cloud Computing
and NFV
• IoT / Embedded
• Edge computing

5. From Unikernel to Unikraft
Pictures form “Unikraft: The second revolution of Unikernels”
• Reduce the effort of converting existing applications to Unikernels
• Easy to configure
• Porting effort requires no rewriting
• Recompiling application code
• Small changes

6. Unikraft architecture
• Library pool(selectable)
• Architecture libraries
• Platform libraries
• OS functional libraries, runtime libraries
• Build tool
• Provides a Linux style kconfig menu
• Provides scripts to integrate/reuse library
• Generates binaries for multiple platforms
automatically
https://www.xenproject.org/developers/teams/unikraft.html

7. Status on arm64 – roadmap overview
Unikraft
Xen Qemu kvm Linuxu
arm32 arm32 arm32arm64 arm64 arm64
Solo5
arm64
Bare mental

8. Footprint and boot time
• helloworld_kvm-arm64, 27 Kbytes
• Boot time: ~50ms on Arm® Cortex®-A53 with QEMU
• Minimal memory usage, 132 Kbytes (not the runtime statistics)
Data form “Unikraft: The second revolution of Unikernels”

9. Status on arm64
• Kvm platform first support on arm64 in year 2018
• Enhancement support on arm64:
• Submitted upstream, but not yet merged
• Ofw (libfdt extended)
• gic v2 irq infrastructure,
• timer support
• multi-thread
• smp first step support
• Solo5 plat support
• Internal review
• virtio-mmio library porting
• backtrace dumping

10. Scalability enhancement
• Multi-thread
• Context switch
• Need to implement GIC interrupt controller libraries for interrupt
infrastructure.
• GICv2 for low cost Arm SoC(e.g. IoT devices)
• GICv3 and GICv4 for high performance Arm SoC (e.g. Arm Servers)
• Need to implement ARMv8 virtual timer library
• Current timer library only provides ticks for timestamp

11. Scalability enhancement
• Smp boot
• Cpu fdt scanning
• Psci boot
• Percpu
• New scheduler
Power
on
Boot
Processor
Scan cpu fdt
Secondary
Processors
WFE
Start up aps
Release APs
Spin until the Boot processor
releases the APs
SEV
AP init
ready
Scheduler Scheduler

12. Future plan
• More lightweight vmm/plat – rust-vmm, solo5, firecracker…
• More performance enhacenment (ECAM PCI controller)
• Integrate DPDK into Unikraft on arm64
• Enable CI/CD of Unikraft
• Add High-level language support (golang, c++, ruby, rust)
• More scalable(enhance smp support)
• Support enhanced debugging facility

13. Summary
• Unikraft reduces the barrier of converting an application to
Unikernel greatly.
• Unikraft is new, it still has some things TODO on arm64.

14. Demo
• A lightweight web server
• Unikraft as a qemu guest (kvm plat on arm64)
• Unikraft in runc (linuxu plat on arm64)

15. References
• Unikraft project wiki:
• https://wiki.xenproject.org/wiki/Category:Unikraft
• Unikraft: The second revolution of Unikernels
• Unikraft: Unikernels Made Easy

16. 16 Confidential Restricted to Arm Board and Executives © 2019 Arm