# DasOS Concepts

## Memory Layout

| Start      | Length     | Length -h | Description                                                              |
|------------|------------|-----------|--------------------------------------------------------------------------|
| 0x00000000 | 0x40000000 | 1 GB      | Kernel Space. This is where the kernel and its functionality is located. |
| 0x00100000 | ???        | ???       | Kernel entry point and load target. Here the kernel will be loaded.      |
| 0x20000000 | 0x20000000 | 512 MB    | Kernel Heap. This memory is used for dynamic allocations in the kernel.  |
| 0x40000000 | 0xC0000000 | 3 GB      | User Space. This is where Artifacts are loaded and executed.             |

### Kernel Heap

A simple storage allocator.

Storage of:
- Task Descriptions
- Memory Mapping Information
- Location of loaded artifacts
- ...

## Starting a Task

### Requirements

- allocate task structure
- allocate mapping directory
- fill mapping directory with
	- Lower End: Copy kernel mappings
	- Upper End: Copy artifact data
- allocate task stack

## Executables, Libraries and Stuff

Artifact = Executable + Library + Shared Memory

### Artifact Types

| Type       | Entry Point |  Description                                                                                                                         |
|------------|-------------|--------------------------------------------------------------------------------------------------------------------------------------|
| Program    | _main       | A program targeted at user or system administrator. Can be executed with command line arguments. Uses stdin, stdout, stderr.         |
| Library    | _libmain    | Can be loaded by other artifacts and allows utilization of a shared set of functions.                                                |
| Service    | _svcmain    | A service is a background worker that won't be terminated when its main function returns. Can be 'woken up' by an external artifact. |
| Driver     | _drvinit    | A driver is loaded at system start and is allowed to request and dispatch interrupts. Can be used to create a flexible OS.           |