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https://github.com/dreamos82/Dreamos64

My experiments with osdev... again
https://github.com/dreamos82/Dreamos64

assembly c kernel operating-system osdev

Last synced: 2 months ago
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My experiments with osdev... again

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# DreamOS64



[![C/C++ CI](https://github.com/dreamos82/Dreamos64/actions/workflows/c-cpp.yml/badge.svg)](https://github.com/dreamos82/Dreamos64/actions/workflows/c-cpp.yml) [![Discord Chat](https://img.shields.io/discord/578193015433330698.svg?style=flat)](https://discordapp.com/channels/578193015433330698/578193713340219392) ![](https://tokei.rs/b1/github/dreamos82/Dreamos64)



DreamOS64 is just my recent attempt to write a kernel again after many years far from osdev,

But this time in 64bit.



It is not a real replacement of the original DreamOS, and i don't really have any long term plans for it at the moment.



I started this project because i was missing the excitement of low-level programming :)



## What it does



Actually not much! :D



It just prints the OS name, a logo and few other string.



But at kernel level several things have been implemented:



* Long mode

* Kernel load in higher half

* Basic I/O functions (using the VGA bios)

* Basic framebuffer support (it can print strings on the screen, but only on the first half of the screen, the second half will cause a #PF for now)

* IDT Support

* It can load the kernel using 4kb pages or 2Mb pages

* Added support to access paging data structures with recursion tecnique.

* Implemented basic physical memory manager

* Enabled paging

* Implement basic kheap memory manager

* Added basic kmalloc, kfree

* Support Acpi V1 and V2

* Local Apic support

* IO-Apic support (Keyboard IRQ enable)

* Suppoort for PSF v1 and v2 fonts in framebuffer mode

* Basic keyboard driver and keyboard map (most of the keys are mapped)

* It prints the Epoch time! :)

* Extremely basic multi-task/multi-thread support

* Thread switching, thread_sleep and basic spinlock implementation

* Basic Virtual Memory implementation

* Initial Userspace support (so far can run only an idle userspace thread)

* Basic syscall mechanism (altough no real syscalls are implemented, just one that prints the string "example")



## Prerequisites:



These are the packages required to build and run it:



* nasm

* qemu and qemu-kvm

* grub-mkrescue

* grub-pc-bin

* xorriso

* mtools

* Gcc cross compiler or Clang



To build _Dreamos64_, a toolchain that supports the target architecture is required,  it can be either   `gcc`  (in our case `x86-64`) or `clang` installed.



A complete guide on how to build the `gcc` cross-compiler, can be found [here](https://github.com/dreamos82/Osdev-Notes/blob/master/99_Appendices/E_Cross_Compilers.md), for `DreamOS64` the target architecture will be `x86-64`.



For `clang` we just need to install the `llvm`and the `lld` packages (the exact package name depends on the distribution used).



## Compiling and Running the OS



For a  complete guide on how to build _DreamOS64_ and the parameters that are availables is in the docs folder: [docs/Building.md](docs/Building.md).



### Build the OS



Before building the os we need to copy a PSF font (either v1 or v2) in the fonts folder, and change its name to `default.psf` (even if we are building with framebuffer off).



Once all the parameters in `build/Config.mk` are set, to build just type:



```bash

    make

```



It will use the default goal `build` and produce a bootable iso in the `dist/` folder called.



## Run and Debug



To launch the OS in qemu just use:



```bash

    make run

```



Instead if we type:



```bash

   make debug

```



It will compile the OS with the debug symbols enabled, all the output logging information will be sent to stdio.



Finally:



```bash

   make gdb

```



Will compile the OS with debug symbol, and launch qemu with remote debugging enabled and will wait connection from gdb to start.



### Unit tests



There is a small set of tests implemented using asserts, if you want to run them just run:



```bash

make tests

```



### Known issues



* If at boot with qemu you get the following error message:



```

	Booting from DVD/CD...

	Boot failed: Could not read from CDROM (code 0009)

```

This means you are missing the grub-pc-bin package, and you need to install it.



* If the linking steps fail with several errors message like:



```

src/kernel/framebuffer/framebuffer.c:122: undefined reference to `_binary_fonts_default_psf_start'

```



This means that the fonts folder is missing (you need either a psf v2 or v1 font file in the fonts folder, the file has to be called default.psf)



### And now show time! :)



![image](https://github.com/dreamos82/Dreamos64/assets/59960116/02ae132c-08c8-47a9-9e4d-7bea0e07865f)



### Acknowledgements



Well so far a big thank you goes to [DeanoBurrito](https://github.com/DeanoBurrito) that implemented several stuff for Dreamos64 (x2apic, fixed some bugs, logging, and more to come...) not to mention his precious help explaining things and reviewing my crappy code :)

And his operating system is worth a mention too: [NorthPort](https://github.com/DeanoBurrito/northport)



Finally if you are interested in how to develop a kernel from scratch, you can head to [https://github.com/dreamportdev/Osdev-Notes/](https://github.com/dreamportdev/Osdev-Notes/) a project mantainde by me, and [DeanoBurrito](https://github.com/DeanoBurrito) on how to write a kernel from scratch.