QVM86 was a Linux kernel module to provide x86 virtualization capabilities for the QEMU emulator. Virtualization allowed "emulated" code to be run natively on the host CPU, using the CPU protection mechanisms to intercept and emulate privileged events. It was licensed under GNU GPLv2 license. It was developed as a drop-in replacement for the then closed-source KQEMU, which has since been made available under the GPL. The developer of QVM86 ceased development on January 21, 2007 as they decided that the project had been rendered obsolete by the release of VirtualBox.
Main article: VirtualBox
In January 2007, VirtualBox was released, which has a built-in dynamic recompiler that is based on QEMU. As with KQEMU, it runs nearly all guest code natively on the host, and uses the recompiler only for special situations. In addition, VirtualBox goes through a lot of code analysis and patching via a built-in disassembler to reduce usage of the recompiler to a minimum. VirtualBox is open-source software under the GPL, except for a number of enterprise features.