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

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.