mOS

mOS is the unix-like operating system developed from scratch and aims to POSIX compliant.

Work-in-process features

• [x] Filesystem
• [x] Program loading
• [x] UI (X11)
• [x] Log
• [x] Networking
• [x] Signal
• [x] Terminal
• [x] mOS toolchain
• [x] Port figlet
• [x] Libc
• [x] Port GNU Bash, Coreutils
• [ ] Unit testing
• [ ] Dynamic linker
• [ ] Port GCC (the GNU Compiler Collection)
• [ ] Browser
• [ ] Sound
• [ ] Symmetric multiprocessing

🍀 Optional features

• [ ] Setup 2-level paging in boot.asm

Get started

MacOS

• install packages

  $ brew install qemu nasm gdb i386-elf-gcc i386-elf-grub bochs e2fsprogs xorriso

• open your bash config and add lines below. Depends on your bash, config file might be different. I use

  ohmyzsh

  , so it is

  .zshrc

  # .zshrc
  alias grub-file=i386-elf-grub-file
  alias grub-mkrescue=i386-elf-grub-mkrescue

• run emulator

  $ cd src && mkdir logs
  $ ./create_image.sh && ./build.sh qemu iso

• open another terminal

  $ cd src
  $ gdb isodir/boot/mos.bin
  # in gdb
  (gdb) target remote localhost:1234
  (gdb) c
  

✍🏻 If you get this error

hdiutil: attach failed - no mountable file systems

Ubuntu

• Install gcc cross compilier via https://wiki.osdev.org/GCCCross-Compiler#TheBuild

• Install GCC (Version 9.1.0) & Binutils (Version 2.32).

• Open src/toolchain/build.sh and modify SYSROOT and PREFIX variables to fit in your case

  PREFIX="$HOME/opt/cross"
  TARGET=i386-pc-mos
  # SYSROOT cannot locate inside PREFIX
  SYSROOT="$HOME/Projects/mos/src/toolchain/sysroot"
  JOBCOUNT=$(nproc)

• Install mos toolchain

  $ cd src/toolchain
  $ ./build

• Run Emulator

  $ cd src && mkdir logs
  $ ./create_image.sh
  $ cd src/ports/bash && ./package.sh
  $ cd src/ports/coreutils && ./package.sh
  $ ./build.sh qemu iso

• Open another terminal

  $ cd src
  $ gdb isodir/boot/mos.bin
  # in gdb
  (gdb) target remote localhost:1234
  (gdb) c
  

✍️ To get userspace address for debugging

$ i386-mos-readelf -e program
# find the line below and copy Addr
# [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
# [ x] .text             PROGBITS        xxx      xxx    xxx    00 AX   0   0  4

Unit Test

$ cd test && git clone https://github.com/ThrowTheSwitch/Unity.git unity
$ make clean && make

Debuging

in

build.sh

-s -S

qemu

Monitoring

by default mOS log outputs to terminal. If you want to monitor via file, doing following steps

# src/build.sh#L71
-serial stdio
↓
-serial file:logs/uart1.log

$ tail -f serial.log | while read line ; do echo $line ; done

✍🏻 Using

tail

References

Tutorials

• http://www.brokenthorn.com/Resources
• http://www.jamesmolloy.co.uk/tutorial_html/
• https://wiki.osdev.org

Ebooks

• Understanding the Linux Kernel, 3rd Edition by Daniel P. Bovet; Marco Cesati