On homebrew OS developmentApr 222015
When I was young, my dad encouraged me to learn to program. He sat me down with various computers, which had BASIC (Sinclair Research BASIC in the ZX Spectrum is quite an experience to program - its symbols are tokenised so each single keystroke can type an entire command, with a bunch of modifier keys) or maybe some ancient versions of Turbo Pascal on an IBM XT.
While trying to make platform games, point and click adventure games, text adventure games, simple windowing systems and trying to get some sounds out of Soundblaster-compatible cards on my old 286, I was always interested in the idea of the development of an actual OS. My dad had told me about how DOS was a layer between the hardware and the software, and had shown me Sun Sparcstations running X-Windows at his work, as well as Windows 3.1, so I was aware of the existence of all these different systems, even though I couldn't get to use many of them.
In addition to this, my dad worked as an electronics engineer for some time, so I was also exposed to 8-bit microcontrollers, random hardware and a general interest in electronics. This made things like low level drivers even more interesting, so it's no surprise that I'd spend time thinking about what my own OS might look like, sketching random little windows and things. Of course, 12 year old me didn't really appreciate the complexity in a modern OS!
Saying that, hobby OS development has become a popular pastime amongst software engineers - the existence of websites like osdev.org, /r/osdev, the educational xv6 and the many OS projects on Github show that it's something plenty of people are interested in.
So, as the years have gone by, I've still had the notion, but didn't really do much. The more I learned about OS development and software in general, the more I knew was required, whilst still not really getting started. I had particular concerns about things like virtual memory, where you need to be able to manipulate your page tables from within the linear world of memory as defined by your page tables, which is just mind bending when you're first starting out. After a while of thinking about it though, I found things started to fall into place, and if you take it one step at a time, things start to work.
For my OS, I have some ideas I want to play with:
- Avoid process-oriented computing
Most operating systems bundle applications together, which generally include everything up from an OS interface level up to their UI. I want a data and/or task-oriented OS, where smaller components are tied together to perform everyday, and unusual, tasks, resulting in more code reuse, more powerful problem solving for end users even without programming and providing for distributing tasks over multiple machines on the network.
- Micro-kernel as much as possible
These components can be drivers or pure userspace tasks, but from an API perspective, they should look the same. As much as possible will be in userspace to ensure maximum stability - and if a task dies, components can attempt to recover by restarting the task (and in the case of network distributed processing, moving those tasks onto another machine)
- No "compatibility layers"
Though it'll probably put off new users, I don't intend to have any sort of standard libraries to make file, device or UI access work. Though these are useful for running existing applications, I want my OS to be something different, with APIs to match. The only exceptions will be to allow self-hosting, so there will be shims to allow things like gcc to work that aren't part of the OS, but the toolset.
- Encrypted, versioned file system
Speaks for itself! Everyone deserves privacy, and to be able to recover their files.
- Built in shell is an object-oriented BASIC system
This ties in to my belief that computing is for everyone - anybody should be able to write a little app, a script or whatever they need to perform their basic tasks at home and work. In the '80s most home computers had built in BASIC, allowing people to tinker, but computing has been slowly moving away from this. I'd like my OS to bring this flexibility back, allowing people to use the computer to its full potential and self educate.
I have other ideas, but those are the "big" ones for now!