Virtualization
Virtual machines are of increasing importance not only in the enterprise domain, but also in embedded systems. The main reasons are their ability to support legacy re-use, and to provide a convenient environment in an otherwise bare-bones system. For example, a complete Linux system can be provided as a convenient high-level programming environment for application programs and sophisticated user interfaces. Virtualization supports such an environment while at the same time isolating the safety- or security-critical components or real-time subsystems from interference.
Furthermore, in multi- and many-core systems-on-chip, the indirection provided by virtualization is becoming be essential for effective management of global system resources, in particular energy.
Consequently, virtualization for us is a vehicle for building complete systems on top of the seL4 microkernel (acting as a hypervisor), and an instance of a security architecture. Virtualization is an essential mechanism for our work on safety-critical systems and multi-criticality real-time systems.
Current Activities
Present activities focus two issues:
- reducing the overheads for virtualising systems on top of seL4, both through design and implementation techniques and by improving the kernel API, and
- demonstrating dependability or performance benefits of seL4-based systems.
Much of this work is not virtualization research of its own right, but instead is research that his heavily dependent on virtualization as a mechanism, and drives performance improvements.
An example is leveraging the dependability guarantees of the formally-verified seL4 microkernel to improve the efficiency of database operations (by removing the overheads required to ensure durability on less dependable platforms).
Past activities
Wombat and Darbat
Wombat was our para-virtualized Linux server on L4. It was the first portable (across architectures) version of a virtualized Linux on L4 (possibly the first portable virtualized Linux at all). It is now commercially supported by our spinout company Open Kernel Labs under the name OK Linux. We have consequently discontinued support for Wombat.
Darbat is related project aiming at running a complete Mac OS X system on top of L4, possibly concurrently with a Linux (i.e. Wombat) system. Rather than straight para-virtualization of the Darwin kernel (consisting of Mach, a BSD kernel and IOkit), the Darbat project attempts to remove Mach completely, replace its functionality by plain L4 mechanisms plus some user-level libraries. The aim is to run Darwin and IOkit in different (unprivileged) address spaces.
Pre-virtualization
Pre-virtualization is a new virtualization technique, which dramatically reduces the engineering cost of para-virtualization while maintaining its performance advantage over pure virtualization. Pre-virtualization, like pure virtualization, retains the original host platform architecture. This is achieved by automating the process of virtualising the guest OS.
Itanium Hypervisors
Our pre-virtualization work supports several different hypervisors on the Itanium architecture. One of them (vNUMA) is our own research projects, others are developed elsewhere.
vNUMA
Virtual NUMA (vNUMA) is a virtual machine monitor that provides a virtual shared-memory multiprocessor system on a cluster. It supports a pre-virtualised Linux as a single-system-image operating system. vNUMA aims to provide easy and efficient migration of legacy SMP applications to a cluster.
Xen/ia64
Xen is a widely-used open-source hypervisor. We are targeting Xen for or pre-virtualised Linux and are achieving the same (or better) performance as para-virtualised XenoLinux, with a fraction of the engineering cost.
Linux
Linux itself, more commonly used as a guest OS, can serve as a hypervisor, user-mode Linux (UML) is an example of this. While UML is an example of para-virtualised Linux, our Linux-on-Linux achieves better performance with dramatically reduced engineering cost.
People
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Publications
2011
 
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Prashant Varanasi and Gernot Heiser Hardware-supported virtualization on ARM Proceedings of the 2nd Asia-Pacific Workshop on Systems, Shanghai, China, July, 2011 |
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Gernot Heiser Virtualizing embedded systems – why bother? Proceedings of the 48th Design Automation Conference, San Diego, CA, USA, June, 2011 Special session invited paper |
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Gernot Heiser, Leonid Ryzhyk, Michael von Tessin and Aleksander Budzynowski What if you could actually Trust your kernel? Proceedings of the 13th Workshop on Hot Topics in Operating Systems, Napa, CA, USA, May, 2011 |
2010
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Gernot Heiser and Ben Leslie The OKL4 Microvisor: Convergence point of microkernels and hypervisors Proceedings of the 1st Asia-Pacific Workshop on Systems, New Delhi, India, August, 2010 |
2009
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Matthew Chapman and Gernot Heiser vNUMA: A virtual shared-memory multiprocessor Proceedings of the 2009 USENIX Annual Technical Conference, San Diego, CA, USA, June, 2009 |
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Joshua LeVasseur Device-driver reuse via virtual machines, PhD Thesis, School of Computer Science and Engineering, University of NSW, Sydney 2052, Australia, 2009 |
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Matthew Chapman vNUMA: Virtual shared-memory multiprocessors, PhD Thesis, School of Computer Science and Engineering, University of NSW, Sydney 2052, Australia, 2009 |
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Gernot Heiser Many-core chips — a case for virtual shared memory Proceedings of the 2nd Workshop on Managed Many-Core Systems, Washington, DC, USA, March, 2009 |
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Gernot Heiser Hypervisors for consumer electronics Proceedings of the 6th IEEE Consumer Communications and Networking Conference, Las Vegas, NV, USA, January, 2009 |
2008
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André Hergenhan and Gernot Heiser Operating systems technology for converged ECUs 6th Embedded Security in Cars Conference (escar), Hamburg, Germany, November, 2008 |
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Joshua LeVasseur, Volkmar Uhlig, Yaowei Yang, Matthew Chapman, Peter Chubb, Ben Leslie and Gernot Heiser Pre-virtualization: Soft layering for virtual machines Proceedings of the 13th IEEE Asia-Pacific Computer Systems Architecture Conference, Hsinchu, Taiwan, August, 2008 Best Paper Award! |
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Dhammika Elkaduwe, Philip Derrin and Kevin Elphinstone Kernel design for isolation and assurance of physical memory 1st Workshop on Isolation and Integration in Embedded Systems, Glasgow, UK, April, 2008 |
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Gernot Heiser The role of virtualization in embedded systems 1st Workshop on Isolation and Integration in Embedded Systems, Glasgow, UK, April, 2008 |
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Gernot Heiser Do microkernels suck? , January, 2008 |
2007
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Timothy Roscoe, Kevin Elphinstone and Gernot Heiser Hype and virtue Proceedings of the 11th Workshop on Hot Topics in Operating Systems, San Diego, CA, USA, May, 2007 |
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Peter Chubb, Matthew Chapman and Myrto Zehnder [para]virtualisation without pain 8th Linux.conf.au, Sydney, NSW, January, 2007 |
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Carl van Schaik and Gernot Heiser High-performance microkernels and virtualisation on ARM and segmented architectures Proceedings of the 1st International Workshop on Microkernels for Embedded Systems, Sydney, Australia, January, 2007 |
2006
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Geoffrey Lee and Charles Gray L4/Darwin: Evolving UNIX Conference for Unix, Linux and Open Source Professionals, Melbourne, Vic, Australia, October, 2006 Slides |
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Myrto Zehnder and Peter Chubb Virtualising PCI Gelato ICE, Singapore, October, 2006 |
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Gernot Heiser, Volkmar Uhlig and Joshua LeVasseur Are virtual-machine monitors microkernels done right? ACM Operating Systems Review, 40(1), 95–99, (January, 2006) |
2005
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Gernot Heiser, Volkmar Uhlig and Joshua LeVasseur Are virtual-machine monitors microkernels done right? Technical Report PA005103, NICTA, October, 2005 |
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Joshua LeVasseur, Volkmar Uhlig, Matthew Chapman, Peter Chubb, Ben Leslie and Gernot Heiser Pre-virtualization: Slashing the cost of virtualization Technical Report PA005520, NICTA, October, 2005 |
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Matthew Chapman and Gernot Heiser Implementing transparent shared memory on clusters using virtual machines Proceedings of the 2005 USENIX Annual Technical Conference, Anaheim, CA, USA, April, 2005 |
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Charles Gray, Matthew Chapman, Peter Chubb, David Mosberger-Tang and Gernot Heiser Itanium — a system implementor's tale Proceedings of the 2005 USENIX Annual Technical Conference, Anaheim, CA, USA, April, 2005 Best Student Paper Award! |
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Ben Leslie, Carl van Schaik and Gernot Heiser Wombat: A portable user-mode Linux for embedded systems 6th Linux.conf.au, Canberra, April, 2005 |
2002
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Volkmar Uhlig, Uwe Dannowski, Espen Skoglund, Andreas Haeberlen and Gernot Heiser Performance of address-space multiplexing on the Pentium Technical Report 2002-1, Computer Science Department, University of Karlsruhe, 2002 |