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Technically UEFI provides a lot of functionality which is part of the groundwork of an operating system, such as a file system. In a way, it is a shame that everything gets discarded and reimplemented by the operating system in the process of booting.

I am wondering how much of a functional operating system would it to implement it as a simple a UEFI application. I am thinking of a graphical user interface and multitasking. Using FAT32 as a file system, UEFI should do well for a lot of purposes and so should identity mapped memory. It would make a very lean and simple operating system, probably even without the need for installation.

The question is where would the limits be of what is feasible to provide in terms of functionality of a full fledged operating system? Any suggestions?

Razor
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Thomas F.
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    I suspect it would be too inflexible. Certainly, very few would want a cooperative multitasker; it would be slower than Ruby running on an abacus with rusty wires. FAT32 is dead, (at least for non-trivial systems). – Martin James Apr 19 '16 at 10:40

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Please don't.

UEFI has no isolation and exposes all it's state, drivers, handles and protocols directly to the user, like DOS did back then.

There is no virtual addresses, there is no user mode, there is no privilege levels, but there is a bunch of code written with an intent to work fast and be discarded fast. Any UEFI application that interacts with the user is a potential security disaster waiting to happen.

Call gRT->ExitBootServices as soon as possible and boot Linux, QNX, L4, Redox or whatever proper OS kernel you like.

CodeRush
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