6 Feb. 2017, https://wiki.qemu.org/Features/KVM. I mean, are they the same, or are they different? [2], As previously mentioned, QEMU can run independently, but due to the emulation being performed entirely in software it is extremely slow. Great! KVM helps QEMU to access hardware virtualization features on different architectures. The differences between QEMU and KVM are not always clear. Though QEMU can run on its own and emulate all of the virtual machine’s resources, as all the emulation is performed in software it is extremely slow. ↩︎, "QEMU - Wikipedia." However, this has now been merged into QEMU upstream and the fork has now been discontinued. Accessed 9 Jan. 2020. Subscribe today and get access to our private newsletter and latest updates! Whether you are running VNF’s in OpenStack or deploying virtual environments within GNS3 or EVE-NG, it is important to understand the different virtualization technologies, such as QEMU and KVM, even for us network engineers. These technologies provide the ability for a slice of the physical CPU to be directly mapped to the vCPU. Twitter To overcome this, QEMU allows you to use KVM as an accelerator so that the physical CPU virtualization extensions can be used. Aren't they both hypervisors? One difference between them is that QEMU runs on a processor without needing for hardware virtualization extension (Intel VT/VT-d, AMD-V) while KVM uses it. Let’s dive in ... QEMU is a userland type 2 (i.e runs upon a host OS) hypervisor for performing hardware virtualization (not to be confused with hardware-assisted virtualization), such as disk, network, VGA, PCI, USB, serial/parallel ports, etc. To overcome this, modern processors support virtualization extensions, such as Intel VT-x and AMD-V. https://en.wikipedia.org/wiki/QEMU. Great! When execution of a code can run natively (meaning CPU opcode that does not require IO), it uses KVM kernel module system calls to switch execution to run natively on the CPU, while the QEMU device model is used to provide the rest of the required functionality. [3], Figure 1 - High-level overview of the KVM/QEMU virtualization environment.[4]. When a CPU is emulated (vCPU) by the hypervisor, the hypervisor has to translate the instructions meant for the vCPU to the physical CPU. Accessed 9 Jan. 2020. http://saravananlinux.blogspot.com/2015/07/kvm-qemu.html, https://en.wikipedia.org/wiki/Kernel-based_Virtual_Machine, Top 5 Up and Coming Network Automation Tools, A Beginners Guide to Docker and VS Code (Part 2), A Beginners Guide to Docker and VS Code (Part 1), Network Automation 101 - Skills and Technologies. Check your inbox and click the link to confirm your subscription. Accessed 9 Jan. 2020. Or in other words, as per Linux KVM, The kernel component of KVM is included in mainline Linux, as of 2.6.20. Rick Donato is the creator of Packet Flow and currently works as a Senior Network Automation Consultant at Network to Code. ↩︎. The differences between QEMU and KVM are not always clear. ↩︎, "Linux KVM." It is flexible in that it can emulate CPUs via dynamic binary translation (DBT) allowing code written for a given processor to be executed on another (i.e ARM on x86, or PPC on ARM). Check your inbox and click the link to complete signin. https://en.wikipedia.org/wiki/Kernel-based_Virtual_Machine. Twitter. ↩︎, "KVM & Qemu - saravananlinux." Accessed 9 Jan. 2020. Network Automation 101 - The What and the Why? https://www.linux-kvm.org/page/Main_Page. 2015, http://saravananlinux.blogspot.com/2015/07/kvm-qemu.html. It is a type 1 hypervisor that is a full virtualization solution for Linux on x86 hardware containing virtualization extensions (Intel VT or AMD-V)[1]. Finally, It is also worth mentioning a little history, which in my opinion has led to some of the confusion around KVM/QEMU.