We most associate hypervisors and virtualization with servers from their beginnings as tools for development and testing, through their widespread adoption as a means to reduce the number of physical servers needed, to their current stage as a foundation for dynamic IT architectures. Virtualization on the client side has been more of a niche although application virtualization continues to grow in importance and some specific uses, such as running Windows applications on Macs, have proven quite popular.
As for embedded devices, special-purpose computers, virtualization has had essentially no impact.
That's beginning to change. Wind River, one of the major players in embedded operating systems and recently purchased by Intel, today announced the availability of Wind River Hypervisor. From the press release:
Wind River Hypervisor enables virtualization for devices across a broad range of market segments, including aerospace and defense, automotive, consumer devices, industrial, and networking. Within these markets, embedded developers are adopting hypervisors to enable the replacement of multiple boards or CPUs with a single board and/or a single CPU, create innovative new devices that leverage multiple operating systems, and reduce complexity when integrating multicore processors. The benefits of using the Wind River Hypervisor include reduced hardware costs and power consumption, opportunity for innovation, and accelerated time-to-market.
This hypervisor can be employed in a number of different ways on a multicore processor. For example, it can be used to run multiple operating system (OS) and application instances on a single processor as a way of enabling single-threaded applications to access multicore performance.
However, what's probably the most interesting use case is consolidating different operating systems on a single processor--and thereby potentially reducing the otherwise need for separate chips or devices. This hypervisor targets two primary operating systems: Wind River's VxWorks and Wind River Linux. To understand why mixing these two might be interesting and useful, consider the differences between them.
VxWorks is Wind River's proprietary "hard real-time" operating system. It's widely used in places like aerospace and defense (think radar, avionics, and so forth) and the data processing of network gear.
Real-time, in general, refers to operating systems and software that have a very predictable response time to events. Predictability runs in opposition to overall throughput so commercial operating systems have historically not been real-time operating systems. Hard real-time typically refers to the need to have truly guaranteed response with the possibility of failure or damage if a response is not made in time.
Wind River Linux is the company's version of Linux optimized for embedded devices. In 2007, Wind River acquired FSMLabs, a real-time Linux vendor, to augment its Linux efforts. Wind River had earlier had a partnership with Red Hat, now discontinued.
Without going into all the gory details of schedulers and so forth, suffice it to say that the real-time characteristics of Linux have improved considerably over the years. Furthermore, various patches can further optimize Linux for real-time uses. Today, we see Linux in applications (such as this IBM/Raytheon deployment) that would have historically been well outside the realm of even customized general-purpose software.
That said, an operating system like VxWorks retains a specialized focus on real-time and comes in versions that carry stringent certifications. Thus, there are many situations where it may make sense to use VxWorks for those parts of an application that require those certifications or are otherwise better served by the specialized real-time OS. At the same time, Linux may be a better fit for other parts of the application that can leverage the Linux ecosystem for components such as user interfaces.
In addition to having different technical requirements, embedded systems make for a somewhat different virtualization use case than in enterprise IT. In embedded, operating systems remain far more specialized and bespoke and this makes the ability to mix and match them on increasingly powerful and multicore processors very useful. This is another face of increasingly pervasive virtualization.