Abstract

We are now used to being roused out of bed by news of the latest serious Internet security alert or major data leak. The software services we now use are tremendously complex, and mash together a complex spectrum of policy and mechanisms. I’ll talk about MirageOS, a clean-slate operating system we’ve been building in the Computer Lab which unifies these services around the principles of functional programming and library operating systems.

Hypervisors such as Xen provide a flexible platform to host applications as a set of appliances, e.g., web servers or databases. Each appliance usually contains an OS kernel and userspace processes, within which applications access resources via APIs such as POSIX . The flexibility comes at a cost: the addition of another layer in the already complex software stack that reduces performance and increases the size of the trusted computing base.

MirageOS proposes a radically different way of building these appliances by breaking up conventional OS libraries into a set of structured, reusable modules. Mirage supports the progressive specialisation of functional language (OCaml) application source code, and gradually replaces traditional OS components with type-safe libraries. This ultimately results in small, sealed, fixed-purpose images that run directly on the hypervisor without an intervening guest OS such as Linux.

Developers no longer need to become sysadmins, expert in the configuration of all manner of system components, to use cloud resources. At the same time, they can develop their code using their usual compiler tools, and simply recompile into specialized kernels when ready. The deployed kernels are also highly compact: facilities that are not used are simply not included. For example, the self-hosting Mirage web server image is less than a megabyte in size!

MirageOS 1.0 is due for a first public release on Dec 9th, so this talk will be presented using MirageOS itself to host the slides.