Beautiful Architecture

The Challenges of Virtualization At a high level, operating system virtualization is used to multiplex several virtual machines ...

that communicate directly with the virtualization layer. The technique was first used in Denali, a virtual machine monitor that ...

This is crucial for protecting processes from one another in a regular operating system. Therefore the kernel must ask the hyper ...

Xen Physical Memory VM 1 VM 0 VM2 FIGURE 7-2. Virtual machine memory layout HOW ELSE COULD YOU DO IT? The standard means of virt ...

network device might be attached to a software network bridge, which is itself attached to a real network card. The ring buffer ...

Dom0 DomU DomU Hypervisor Hardware Management and control software Guest Service Guest App Guest Apps FIGURE 7-4. Xen system arc ...

Hosted virtual machines are typically used for desktop virtualization: they allow a user running, say, Mac OS X to run Linux in ...

added in domain zero rather than in the hypervisor, where additional complexity is generally undesirable. Earlier we noted how X ...

enable efficient and secure communication between domains. Thanks to device channels, Xen’s virtual devices achieve near-native ...

waits until it knows that the notification was received. As Figure 7-8 shows, this mode of operation leads to poor performance, ...

This model has been applied to other parts of domain zero. The latest versions of Xen include stub domains, which provide device ...

Virtualized and emulated systems differ in how each instruction is executed. In a virtualized system, applications and most of t ...

DomIO Physical memory IOMMU 1) Send pseudo-physical address to device 3) DMA request with physical address 2) DMA request with p ...

Lessons Learned Looking back, there are two main lessons that can be drawn from Xen: the importance of paravirtualization, and t ...

the largest contributions have come from Intel and AMD, who provided much of the code to support hardware virtual machines. This ...

Finally, Xen is under active development and continually evolving. The best way to keep abreast of new developments is to downlo ...

C H A P T E R E I G H T Guardian: A Fault-Tolerant Operating System Environment Greg Lehey ARCHITECTURE IS NOTHING NEW. REAL BUI ...

directly contribute to fault tolerance—in fact, a couple detract from it! So prepare for a voyage into the past, back to about 1 ...

Interprocessor bus (IPB) Controller Disk controller Disk controller CPU 0 CPU 1 $SYSTEM $DATA I/O bus I/O bus FIGURE 8-1. Mackie ...

It’s not enough for a CPU to fail, of course; other CPUs have to find out that it has failed. The solution here is a watchdog. E ...