Since my 15 years old, I always wanted to know how an x86 OS works.
So, after a lot of restart, I have decided to work a very small kernel.
To start the kernel using the qemu Emulator:
qemu-system-i386 -cdrom https://courchinoux.org/OS/gaspardos1.iso
Is a monolothic kernel for x86 not x64.
It is a multiboot 1 kernel. It means that GNU grub must start the system.
Also, it supports the x86 interrupts, exceptions of course.
On december 2, 2024 I have added the support of multitasking.
The multitasking is very simple, is alloc a stack for the function and modify esp and eip. It's a preemptive multitasking. On each timer interrupt, the system switch.
To enable multitasking, you need to enter "m" in the FORTH prompt. It will switch to a demo between two function.
The hardest part for me was to implement the paging system.
For paging, I don't have a PHD in computer science, i have decided to make it simple. The first 4MB physical are identity paging.
Beyond that, a very simple physical adress allocate physical memory to virtual memory using paging structure.
Normally, 4GB are supported !
Please note that only virtual machine are supported. I have tested the system on qemu mainly and virtualbox.
I used the forth programming language to make an interactive experience for the user.
You can make some mathematical operations using the forth. In the future, my implementation will be able to access to filesystem and network operations.
Forth is a stack programming language. It uses the reverse Polish notation.
I will not explain what it's the reverse Polish notation. But, currently in my implementation you don't need to use variable.
In fact, all the variables are pushed on the stack. For example, to make a addition :
Now, you can erase with return key.
FORTH: 5
FORTH: 4
FORTH: +
FORTH: .
Unfortunately, you can't push 2 values in the same time to the stack. It's a bug, I'm working hard to resolve it.
To validate the input, you need to press the spacebar not enter.
- Resolve the push BUG.
- Add more forth command.
- Ethernet support.
Improve multitasking.
Support ELF.