A basic operating system project built entirely from scratch.

Official website: https://z3r0flag.github.io/SysZero

bash, gcc, nasm, gnu make, gnu ld, (optionally virtualbox to convert .bin drive to .vmdk)

To build, simply run this command in the project root: ./automake

• make all - builds the operating system disk image (100MB) in raw binary mode only
• make raw - (same as make all) builds the operating system disk image (100MB) in raw binary mode only
• make convert_vmdk - converts the raw binary OS image into vmdk mode, leaving the raw binary image
• make clean - clean up build files and executables
• make run - runs the system in QEMU (no compilation/building is done)
• make run_gtk - same as above but uses gtk display with gl acceleration
• make run_sdl - same as above but uses sdl display with gl acceleration
• make ESFS_raw_write - builds the program required for writing files from host machine to ESFS on raw binary disk

I have written a program that is able to copy the exact bytes of a file on your host machine to the virtual hard disk of the OS, to compile it view the "Makefile rules" section. The program is only able to write data to a raw binary virtual disk (os-image.bin). DO NOT TRY TO WRITE TO os-image.vmdk.

Usage:

• make clean raw ESFS_raw_write
• ./ESFS_raw_write os-image.bin file_name_in_ESFS file_name_on_local_machine
• make convert_vmdk

You will now be able to either boot the .bin image in QEMU or the .vmdk image in Virtualbox/VMware (if you have those installed) and it will contain the file(s) which you have copied onto the disk. Keep in mind that once a disk is converted to .vmdk mode, it can no longer be written to by ESFS_raw_write.

The kernel shell is an interface for executing binaries stored as files on the virtual hard disk. (For a C program to be automatically built and written onto the virtual disk by the Automake script, put the .c source file in external_programs)

• Write the program in C, you will be able to include any kernel API that is available. View the header files inside the kernel directory to see the options.

• Compilation can be done through the simple compile_program script in the format ../compile_program <input_file.c> <output_file> it is important that you execute the script while being in the external_programs directory. The script will compile your program together will all available kernel API.

• Writing your program to the OS virtual disk can be done in the same way as writing a standard text file, the procedure is described in the "How to copy files from host machine to OS virtual hard disk" section.

The automake script is easy to use, it will build the operating system as well as all .c files in external_programs/ and write the executable binaries to the operating system's virtual drive, an option will be provided to write any additional files to the disk before conversion to VMDK format.

There exist two scripts create_create_virtual_disks and run_with_extra_disks. (The latter is just a single long qemu command to virtualize SystemZero with 4 virtual IDE drives). The first script creates 3 virtual IDE drives (the first one is the boot drive). These can be "connected" to any of the 4 IDE busses and accessed within SystemZero.

run_with_extra_disks gtk & run_with_extra_disks sdl options are also available. See Makefile rules to see what those options do.