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going public :^)
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‎.gdbinit

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file /share/build/kernel.elf
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gef-remote --qemu-user --qemu-binary /share/build/kernel.elf localhost 1234

‎.github/workflows/ci.yaml

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name: Pipeline
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on: push
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jobs:
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build-os:
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runs-on: ubuntu-20.04
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steps:
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- name: Checkout repo
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uses: actions/checkout@v4
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- name: Install deps
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run: |
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chmod +x ./deps-container.sh
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sudo ./deps-container.sh
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- name: Compile Kernel
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run: |
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make dirsetup
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make kernel
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- name: Compile Filesystem/Userland
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run: make fs
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- name: Build iso image
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run: make iso

‎.gitignore

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later/
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build/
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iso/targets/x86/boot/kernel.bin
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.vscode/
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tmp/
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.cache/
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*.o
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**/*.o
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disk.img

‎Makefile

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CC=gcc
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ASM=nasm
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LD=ld
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CFLAGS=-ffreestanding -fno-pic -static -fno-builtin \
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-fno-strict-aliasing -O2 -Wall -ggdb -m32 \
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-Werror -fno-omit-frame-pointer -fno-stack-protector -mno-80387 -Wno-div-by-zero
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SRC_DIR=src
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INC_DIR=src -I/usr/include/ -I/usr/include/x86_64-linux-gnu
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BUILD_DIR=build
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DISK_IMG=disk.img
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KERN_SRC_DIR=$(SRC_DIR)/kernel
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KERN_OBJ_DIR=$(BUILD_DIR)/kernel
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DRIVERS_SRC_DIR=$(SRC_DIR)/drivers
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DRIVERS_OBJ_DIR=$(BUILD_DIR)/drivers
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# $(wildcard *.cpp /xxx/xxx/*.cpp): get all .cpp files from the current directory and dir "/xxx/xxx/"
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# $(patsubst %.cpp,%.o,$(SRCS)): substitute all ".cpp" file name strings to ".o" file name strings
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KERNEL_SRCS := $(wildcard $(KERN_SRC_DIR)/*.c)
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KERNEL_SRCS += $(wildcard $(KERN_SRC_DIR)/*.S)
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KERNEL_OBJS := $(patsubst $(KERN_SRC_DIR)/%.c,$(KERN_OBJ_DIR)/%.o,$(KERNEL_SRCS))
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KERNEL_OBJS := $(patsubst $(KERN_SRC_DIR)/%.S,$(KERN_OBJ_DIR)/%.o,$(KERNEL_OBJS))
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DRIVER_SRCS := $(wildcard $(DRIVERS_SRC_DIR)/*.c)
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DRIVER_OBJS := $(patsubst $(DRIVERS_SRC_DIR)/%.c,$(DRIVERS_OBJ_DIR)/%.o,$(DRIVER_SRCS))
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CPUS=1
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QEMU_OPTS=-smp $(CPUS) -m 512 -serial pty -serial stdio
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dirsetup:
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mkdir -p $(DRIVERS_OBJ_DIR)
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mkdir -p $(KERN_OBJ_DIR)
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python3 ./gen_vectors.py > $(KERN_SRC_DIR)/trap_dispatcher.S
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# drivers
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# -------------------------
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build/drivers/%.o: src/drivers/%.c
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@echo "[*] Compiling $^"
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$(CC) $(CFLAGS) -fno-pic -nostdinc -I$(INC_DIR) -c $^ -o $@
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drivers: $(DRIVER_OBJS)
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@echo "[*] ======= Done compiling drivers ======="
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# kernel (C sources & assemblies)
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# -------------------------
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build/kernel/%.o: src/kernel/%.c
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@echo "[*] Compiling $^"
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$(CC) $(CFLAGS) -fno-pic -nostdinc -I$(INC_DIR) -c $^ -o $@
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build/kernel/%.o: src/kernel/%.S
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@echo "[*] Compiling $^"
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$(CC) $(CFLAGS) -fno-pic -nostdinc -I$(INC_DIR) -c $^ -o $@
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kern: $(KERNEL_OBJS)
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@echo "[*] ======= Done compiling kernel ======="
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kernel: kern drivers
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@echo "\n[*] ======= Linking kernel.elf ======="
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$(LD) $(LDFLAGS) -T$(KERN_SRC_DIR)/kernel.ld -o $(BUILD_DIR)/kernel.elf $(KERNEL_OBJS) $(DRIVER_OBJS) -b binary
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# OS image
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# -------------------------
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iso: kernel fs
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@echo "\n[*] ======= Making iso image w/ GRUB bootloader ======="
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cp $(BUILD_DIR)/kernel.elf iso/targets/x86/boot/kernel.bin && \
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grub-mkrescue /usr/lib/grub/i386-pc -o $(BUILD_DIR)/kernel.iso iso/targets/x86
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clean:
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rm -rf $(BUILD_DIR)/*
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$(MAKE) clean -C ./src/userland/
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# Emulation & debugging
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# -------------------------
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qemu:
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qemu-system-i386 -cdrom $(BUILD_DIR)/kernel.iso $(QEMU_OPTS)
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qemu-nox:
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qemu-system-i386 -nographic -boot d -cdrom $(BUILD_DIR)/kernel.iso -hda $(DISK_IMG) $(QEMU_EXTRAS)
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qemu-gdb:
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@echo "\n[*] ======= starting QEMU+gdb ======="
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@echo "[*] To close: Ctrl-A X"
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@echo "Starting "
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qemu-system-i386 -s -S -nographic -boot d -cdrom $(BUILD_DIR)/kernel.iso -hda $(DISK_IMG) $(QEMU_EXTRAS)
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# Disk / filesystem
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# -------------------------
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disk:
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@echo "\n[*] ======= Generating FAT32 disk image ======="
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dd if=/dev/zero of=disk.img bs=1M count=1
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mkfs.vfat -F 32 disk.img
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fs: disk
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$(MAKE) fs -C ./src/userland/

‎README.md

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# GenesisOS
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curiosity got me here
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<p align="center">
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<img src='docs/images/logo.png' />
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<br />
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<img src='https://github.com/0xbigshaq/GenesisOS/actions/workflows/ci.yaml/badge.svg' />
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<a href='https://discord.gg/PpeeR64k'><img src='https://img.shields.io/discord/1231650335802789959.svg?logo=discord&logoColor=white&logoWidth=20labelColor=7289DA&color=17cf48&label=Discord' /></a>
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<img src='https://img.shields.io/badge/arch-x86/32bit-blue' />
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</p>
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Dumb project I made because I wanted to learn about kernels and how they work. You are welcomed to contribute to my chaos and join the cult.
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This operating system have the following features:
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* Kernel allocator
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* Virtual Memory
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* Interrupts / IRQs
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* Disk: ATA PIO
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* Syscalls
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* Scheduler (_Round-Robin_ algorithm)
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* Console/UART driver
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* Filesystem: Support FAT32
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* ELF Loader
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* Userland shell/init binary
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* Devices/File descriptors(not rly/partial)
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All this work, just to load an ELF binary that echoes back whatever you write to it by calling `SYS_read` and `SYS_write`:
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<img src='docs/images/terminal.gif' />
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To write this project, I used:
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* _Intel SDM Vol 3_(`325384-sdm-vol-3abcd.pdf`)
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* OSDev Discord community([link](https://discord.gg/osdev))
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* OSDev: https://wiki.osdev.org/
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* "_The little book about OS development_": https://littleosbook.github.io/
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* Academic projects: SerenityOS, JOS and xv6 (to get inspiration for design ideas)
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* _nanobyte-dev_ YT channel to get introduction on FAT filesystems.
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# Build & Run
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Launch an `ubuntu:20.04` container and follow the steps below
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```sh
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docker run -v $(pwd):/share/ --rm --privileged --name osdev -it ubuntu:20.04
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```
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1. First, run `./deps-container.sh` to install the required dependencies.
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2. prepare the directory tree by running `make dirsetup`
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3. Compile & pack everything by running `make iso`
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4. To run the OS in qemu, run `make qemu-nox`
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>Note: _nox_ stands for _no-graphics_. If you run `make qemu` a qemu window will pop. However, it has bugs because the video driver is not finished(unlike the UART/console driver, which is more mature)
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# Debug
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To debug:
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1. Run `make qemu-gdb`
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2. Connect with gdb by running `target remote :12345`
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# Security
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Found a security issue? Good, fix it and send a PR.
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>There are plenty of vulns around the codebase. I'm considering opening a special activities/event for vuln researchers who are interested in OSDev so we can learn and grow together. Should update about it in the Discord server.
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# Compile DB
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For easier code navigation and auto-completion, use _clangd_'s vscode plugin + [compiledb](https://github.com/nickdiego/compiledb).
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```
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compiledb make iso
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```

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