ACRN Arrives on the Scene as a Mini Hypervisor for IIoT

by Paul Rubens

It's not yet clear who the major users will be for the hypervisor pronounced "Acorn," but most likely it will be a case of "if you build it, they will come."

Hypervisors are pretty complex pieces of software, and that means new ones don't appear on the scene very often — although a few new hypervisors designed for container environments have hit the headlines in the last year or so.

But alongside containers, there is one other area of technology that has been touted to become huge in the next few years, and that's the Internet of Things (IoT), which includes the potentially mega-huge Industrial Internet of Things (IIoT). (To get some idea of scale, worldwide IIoT spending was estimated at about $20 billion in 2012, but it is forecast to reach $500 billion by 2020.) Virtually Speaking

With that in mind, the arrival on the scene of ACRN (pronounced "Acorn") should not come as a huge surprise. What is ACRN? Put simply, it is an open source reference hypervisor that has been built to meet the unique needs of embedded IoT development. It was announced by the Linux Foundation in late March.

This begs an obvious question or two: what exactly are the unique needs of embedded IoT development, and why are they so important that an existing data center hypervisor such as Xen, which is already hosted by the Linux Foundation, can't fulfill them?

The Need for a Smaller Hypervisor with Prioritization Capabilities

The first need is for something smaller. It won't come as a surprise that data center hypervisors tend to be large, while IoT devices have very limited resources. The good news is that ACRN comes in at just 25,000 lines of code, compared to about 160,000 for the average data center hypervisor — that's less than one sixth of the size.

The other main need is the ability to prioritize some workloads over others. That's needed because one of the expected uses for ACRN is in the automotive industry, where different workloads running on different modules will one day run on a single system isolated by a hypervisor like ACRN.

Since ACRN can prioritize, it can ensure that workloads running in a "safety/security critical domain" can seize control of resources when needed at the expense of workloads in the "non-safety critical domain."

And in fact, that capability is not just of interest to the automotive industry, as Jim Zemlin, the Linux Foundation's executive director, explains. "ACRN's optimization for resource-constrained devices and focus on isolating safety-critical workloads and giving them priority make the project applicable across many IoT use cases," he says.

Of course, some embedded hypervisors exist already, but the ACRN folks argue that they are highly dependent on closed-source proprietary solutions, they are expensive, and they have a hard partition with no ability to share resources.

So a final key feature of ACRN is the very fact that it is open source and available to all via GitHub, and using it will offer the potential for significant R&D and development costs savings.

"ACRN will have a Linux-based service OS and the ability to simultaneously run multiple types of guest operating systems providing a powerful solution for workload consolidation," says Imad Sousou, corporate vice president and general manager of the Open Source Technology Center at Intel Corporation, which has contributed a significant proportion of ACRN's code.

It's still early days for ACRN, and it's not yet clear who the major users will be. But most likely it will be a case of "if you build it, they will come." Don't be surprised if, a few years from now, many of the cars on the road have ACRN running at the heart of their control systems. But things change pretty fast in the virtualization and container space these days, so then again, don't be surprised if many cars are not.

Paul Rubens is a technology journalist and contributor to ServerWatch, EnterpriseNetworkingPlanet and EnterpriseMobileToday. He has also covered technology for international newspapers and magazines including The Economist and The Financial Times since 1991.

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This article was originally published on Wednesday Jun 27th 2018
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