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Haribote OS

Haribote OS is originally created by Hidemi Kawai, introduced in a book called "30日でできる! OS自作入門"

  • x86, 32 bit OS
  • Boot from floppy disk
  • preemptive multi task
  • Window like system
  • 256 color screen mode

Screenshots

Screenshot

fpu applications

See more

Required environment

  • Linux
  • gcc, as, ld
  • make
  • Ruby

Originally, Windows + nask + gcc and lots of tools are used for the original development environment. But I changed to use Linux, and simplify required tools using Ruby.

How to build

  • Type make in the root directory
  • haribote.iso is created
  • Burn image into CD, or run disk image using PC emulator (e.g. VirtualBox)

Directory structure

Name Entry
kernel Boot loader & OS
include Header files for application
lib Library files for application
apilib API source codes
tools Tools for building OS, disk image
apps applications (not OS itself)

Docker

You can run a build process in a docker container:

  • First time: Run make docker-build to create haribote:dev docker image.
  • make docker-make to run a build procss in the container.

How to make your own .hrb application

Create executable for Haribote OS

  1. Create object files using gcc
    1. int main(int argc, char* argv[]) function is the entry point.
  2. Use linker script hrbapp.ls to make .hrb file
    • $ ld -T hrbapp.ls lib/crt0.o -o <executable file name> <object files...> lib/libhrb.a
    • You have to link lib/crt0.o and lib/libhrb.a

Put executable onto floopy disk image

  1. Prepare disk image
    1. Format: $ tools/fat12img <image file name> format
    2. Write boot sector: $ tools/fat12img <image file name> write obj/ipl.bin 0
    3. Write OS first: $ tools/fat12img <image file name> save obj/haribote.sys
  2. Put executable file
    1. $ tools/fat12img <image file name> save <.hrb file>

These sequence is done in $/Makefile.

Execution

QEMU

$ make qemu  # qemu-system-i386 -boot d -cdrom haribote.iso -m 512

Memo

Floppy disk

  • 2HD : 1.4MB = 1,474,560 bytes (= 512 bytes x 18 sectors x 2 heads x 80 cylinders)
Offset Entity
0x000000 - 0x0001ff Boot sector
0x000200 - 0x0013ff FAT
0x001400 - 0x0025ff FAT (back up)
0x002600 - 0x0041ff Root directory table
0x004200 - 0x167fff Cluster data

Haribote OS Memory layout

Address Entity
0x00007c00 - 0x00007dff Boot sector is loaded (512 bytes)
0x00100000 - 0x00267fff Floppy disk image (1440KB)
0x0026f800 - 0x0026ffff IDT (2KB)
0x00270000 - 0x0027ffff GDT (64KB)
0x00280000 - 0x002effff Kernel program (bootpack.hrb, 512KB)
0x002f0000 - 0x002fffff .data, .rodata
0x00300000 - 0x003fffff Stack etc. (1MB)
0x00400000 - Free (application area)

Calling convension

  • For 32bit x86 CPU, eax, ecx, and edx registers don't need to be saved during function call.