Following the release of Intel-based Macs, third-party platform virtualization software such as Parallels Desktop, VMware Fusion, and VirtualBox began to emerge. These programs allow users to run Microsoft Windows or previously Windows-only software on Macs at near native speed. Apple also released Boot Camp and Mac-specific Windows drivers that help users to install Windows XP or Vista and natively dual boot between Mac OS X and Windows. Though not condoned by Apple, it is possible to run <answer>the Linux operating system</answer> using Boot camp or other virtualization workarounds. Unlike most PCs, however, Macs are unable to run many legacy PC operating systems. In particular, Intel-based macs lack the A20 gate.
What is possible to run by using Boot camp, even though it is not condoned by Apple?
the Linux operating system