![]() ![]() New processors launched by both vendors saw the addition of virtualization-specific processor instructions resulting in a much needed boost in performance. ![]() This article makes for an interesting read if you wish to look at the bigger picture.Įnter Hardware-Assisted virtualization, an initiative undertaken by both Intel and AMD in 2005 as a direct response to the issue described above. VMware had actually worked around the problem using a process known as binary translation. The problem in reality is somewhat more complex but this is essentially why a better solution was called for. the level a VM’s guest OS is running in, hence the performance issue. When a software-based virtualization approach is taken, a hypervisor will have to trap and emulate processor instructions which simply cannot be executed at ring level 1, i.e. What this means then is that VM guest operating systems can only run in ring 1. Drivers and similar software, in theory, should run in rings 1 & 2 while application software such as the browser you’re using just now, runs in ring 3. OS kernels generally run in ring 0, the highest privileged level. ![]() This approach, however good, had its limitations and ultimately suffered from performance issues.Īn x86 processor implements what is known as a CPU privilege or protection ring scheme to regulate direct access to system resources. When virtualization started to take root, hardware virtualization was primarily done in software using complex emulation techniques. We take this for granted whenever we run multiple VMs on hypervisors such as ESXi, Hyper-V, XenServer and KVM. Incidentally, isolation is yet another bonus intrinsic to virtualization. All this is accomplished using virtual machines which are isolated instances of the hardware being virtualized. Rather than provision a physical server to host perhaps one or two applications which in most cases sees mediocre system utilization – there are exceptions of course such as high load SQL servers –, the same server could instead be used to run a number of operating systems in parallel each hosting its own application. One of the main benefits of virtualization is that hardware resources such as servers can be exploited to their fullest. Today’s post explores the concept of x86 hardware virtualization which is what allows multiple operating systems to run in parallel on a single x86 based processor. ![]()
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