Out of Hanwell

August 16, 2008

Khoros: A Lua Operating System

Filed under: Development, Linux, My Projects — Tags: , , , , — Matthias Miller @ 4:06 pm

Over the past year or two, I’ve been tinkering with my own operating system, which I’ve dubbed Khoros. The name comes from the Greek word χορός, meaning dance, from which we get our English words chorus and choreography. Of course, I chose this name because of its obvious play on words.

My first task was simply getting a bootable system. Rather than write my own bootloader, I used Grub. I based my work off Brandon Friesen’s excellent tutorial. I initially used VMware for virtualization, but since then, I’ve since switched VirtualBox and have had much better success.

As much as possible, the kernel is written in Lua. (Yes, Microsoft’s Singularity project caught my attention.) I am not particularly gung-ho over Lua as a language, but I picked it for its exceptionally small footprint, and it opens interesting possibilities for sandboxing. For example, my C kernel interfaces high-level interfaces to allocate and manipulate memory. However, the Lua scripts cannot specifically address memory. They can only manipulate memory block within the allocated bounds. This allows very powerful but safe low-level programming for my drivers.

With the past several weeks, I finished up basic multi-process support using Lua’s coroutines and debug hooks. (I am not using traditional process boundaries, so everything is running in kernel mode.) Processes can communicate with each other using a very simple IPC mechanism.

Today, my operating system boots into a simple Lua shell, allowing me to run arbitrary Lua code from the command line. This is no small feat, but it is admittedly of limited use. I am trying to decide how to proceed.

A networking stack could be quite beneficial, since it would allow me to program it remotely or to do something interesting like serve websites. However, this involves learning about the PCI bus, the NIC, ethernet, TCP/IP, DHCP, and many more details of which I am certainly unaware.

Alternatively, I could implement rudimentary file system support. For example, I could provide a way to save Lua objects to disk. However, I am lost to what interesting piece this might lead me to.

I blog so infrequently that I’ve probably lost most of my readership, but to all of you out there, what do you think I should develop next?

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May 28, 2008

Using vim for Word Processing

Filed under: Linux, Software, Tools — Matthias Miller @ 11:24 pm

I’ve recently been using vim for word processing. However, it’s very cumbersome to edit long lines of text because the up/down/home/end keys do not respect wrapping.

Of course, vimrc comes to the rescue:

imap <up> <C-O>gk
imap <down> <C-O>gj
nmap <up> gk
nmap <down> gj
vmap <up> gk
vmap <down> gj
imap <home> <C-O>g^
imap <end> <C-O>g$
nmap <home> g^
nmap <end> g$
vmap <home> g^
vmap <end> g$

And once again, I’m a happy vim user.

Update: And to get soft word wrapping, I added:

set formatoptions=l
set lbr

Now I’m really happy.

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