User Mode Linux (UML) is an interesting concept it is constructed as a separate Linux kernel porting, has its own arch / um subdirectory it is not a run on new types of hardware, however;.. On the contrary, it runs in Called by a Linux system on a virtual machine interface implementation. thus, UML use the Linux kernel to run as an independent on a Linux system user-mode process.
There is a copy of the kernel as a user process has several advantages because they run on a virtual processor is limited, a bad kernel can not destroy the "real" system can easily try different on the same box hardware and software configuration. and, perhaps the kernel developers, the user mode kernel can be easily used gdb debugger and other operations.
After all, it's just a process. UML clearly has the potential to accelerate kernel development.
Indeed ignored pointed out, you should make your network adapter built on the kernel, however, otherwise it will turn off the debugger can not find itself at startup.
However, UML has a big disadvantage from the driver writer's standpoint: user-mode kernel can not access the host system's hardware Thus, although it is for example debugging Most of this book drive is useful, UML to have to deal with. driven debugging real hardware or useless.