UML: User Mode Linux

Linux is a name for a kernel. A kernel is a big piece of tough software that makes the wilderness of hardware behave for the comfort of the user. The user may run applications of varying tastes on the hardware without ever having to explain the billion gates inside of a computer, which way to let the current follow and to hold on which side. It is all taken care of the kernel.

But what if I told you that the kernel too can be run as an application. After all it is in the end a piece of software although a little firm. This idea isn't that alien of course. It kind of resembles virtualization.

You see, Linux being a kernel is meant to work on and with hardware. But if one wishes to run Linux in user mode i.e. like an application then it can't be given the kind of access it needs to the hardware. So what is the best that can done? Visualize an entire machine of hardware in software (simulate) and allow the application (Linux) to run the courses on it. It is important to note that the host for such activities must also be running on Linux.

It is an immediate given that this is fun. Running multiple copies of a kernel on machine simulates having multiple machines working independently of each other on a single big piece of hardware. Apart from being funny, this can also be very useful. The idea of having a kernel but not with unlimited power and almost no authority over your not so free and hence obviously precious hardware makes perfect sense for innovative development and kernel tweaking. You can use this technique to alter the kernel as much as you like without putting your computer in harm's way.

Even if you have some sincere activities planned, you can seek great aid from such virtualization. For example multiple servers can be hosted from a single machine this way. It can also be a great way to teach students about kernels and Linux.

All things said, this technique is not yet comprehensive. There are many leaps of development needed before it becomes more popular and hence starts gaining some developer attention as well.