We propose a method to reuse unmodified device drivers and to improve system dependability using virtual machines. We run the unmodified device driver, with its original operating system, in a virtual machine. This approach enables extensive reuse of existing and unmodified drivers, independent of the OS or device vendor, significantly reducing the barrier to building new OS endeavors. By allowing distinct device drivers to reside in separate virtual machines, this technique isolates faults caused by defective or malicious drivers, thus improving a system’s dependability. We show that our technique requires minimal support infrastructure and provides strong fault isolation. Our prototype’s network performance is within 3–8 % of a native Linux system. Each additional virtual machine increases the CPU utilization by about 0.12%. We have successfully reused a wide variety of unmodified Linux network, disk, and PCI device drivers. 1

Hardware virtualization allows physical hardware of a single computer to be shared between multiple operating systems in a nearly transparent manner. A virtual machine monitor provides each operating system virtual resources which are backed by physical resources of the hardware. Though increasing system complexity somewhat, hardware virtualization saves costs and has a number of other benefits. As the deployment of virtualization increases, dependence on the technology increases accordingly, thus emphasizing the importance of the security of virtualization mechanisms. We present a literature survey of commodity x86 hardware virtualization. We also consider virtualization security from two viewpoints: we first develop a security model for virtualization using an asset-threats approach, and then consider how virtualization can be used to improve system security. Finally, we discuss security oriented virtualization architectures, and the relationship between trusted computing, the Trusted Platform Module (TPM), and virtualization.