Linux VM Without VM Software – User Mode Linux
6 months ago
- #Kernel
- #Linux
- #Virtualization
- Linux can run as a userspace application called UserMode Linux (UML), allowing the kernel to operate within another kernel instance.
- UML leverages paravirtualization, where drivers are aware they're running on virtualized hardware, optimizing performance.
- The UML kernel runs as a userspace process, using host facilities like files and sockets instead of physical hardware.
- Building a UML kernel requires configuring it with ARCH=um and enabling specific options like BLK_DEV_UBD for virtual block devices.
- A minimal userspace can be created using tools like Buildroot to run within the UML kernel.
- UML is primarily useful for kernel debugging and experimentation rather than production virtualization, offering a unique niche between full VMs and containers.