PhobOS

This is a study project for operating systems development for x86-64. Based on:

• http://wyoos.org
• http://wiki.osdev.org
• http://www.jamesmolloy.co.uk/tutorial_html
• http://os.phil-opp.com/multiboot-kernel.html
• http://developer.amd.com/wordpress/media/2012/10/24593_APM_v21.pdf
• https://www.intel.com/content/dam/support/us/en/documents/processors/pentium4/sb/25366821.pdf

Credits to the authors!

Showcase

Booting

Simple dir tree demo

Simple plot demo

Simple arkanoid demo

Features

• GRUB2 bootable
• 64 bit kernel
• memory paging (2MB pages) and on-page-fault allocator
• stack guard page
• managed dynamic memory
• higher-half kernel
• multitasking
• kernel/user space
• ELF64 support (statically linked only) - some basic syscalls implemented, see: syscalls.h
• virtual filesystem
• MBR/Fat32 driver (no long names)
• PS/2 mouse driver
• Keyboard driver
• VGA driver (90x30 text mode, 320x200 graphics mode for now)
• Simple terminal emulator (with TAB auto-completion) and a few basic system commands like cd, cat, cp, mkdir

Need install

• cmake, at least v3.10
• xorriso (for building bootable iso PhobOS image)
• mtools (for fat32 formatting of PhobOS virtual drive)
• qemu-system-x86_64, with qemu-nbd (for running PhobOS, for mounting virtual phobos drive in linux)

Run it (tested on ubuntu 16.04 & manjaro 17.1.12)

sudo ./remount_hdd.sh
./build_kernel.sh && ./build_user.sh && ./run.sh

Debug it in terminal

sudo ./remount_hdd.sh
./build_kernel.sh -DCMAKE_BUILD_TYPE=DEBUG && ./build_user.sh && ./rungdb.sh
gdb -symbols=build/kernel/kernel/phobos-x86_64.bin -ex "set arch i386:x86-64:intel" -ex "target remote localhost:1234"
(gdb) break kmain
(gdb) continue
(gdb) ^a + ^x

Debug in Eclipse

Run->Debug Configurations... ->C/C++ Remote Application->add
Set Project to PhobOS
Set "Using GDB(DSF) Manual Remote Debugging Launcher" instead of Automatic one
Under Debugger->Connection tab set:

• Stop on startup at: kmain
• Port number to 1234

(terminal) ./build_kernel.sh -DCMAKE_BUILD_TYPE=DEBUG && ./build_user.sh && ./rungdb.sh
(eclipse) Debug->our newly created configuration

Debug in VS Code

Install Native Debug from market
launch.json:
{
"version": "0.2.0",
"configurations": [
{
"type": "gdb",
"request": "attach",
"name": "Attach to QEMU",
"executable": "${workspaceRoot}/build/kernel/kernel/phobos-x86_64.bin",
"target": ":1234",
"remote": true,
"cwd": "${workspaceRoot}"
}
]
}
(terminal) ./build_kernel.sh -DCMAKE_BUILD_TYPE=DEBUG && ./build_user.sh && ./rungdb.sh
(vscode) Debug->"Attach to QEMU"

GDB pretty printing of STL containers

• Install python3
• Create .gdbinit in project folder with following contents:
  python
  import sys
  sys.path.insert(0, '/home/mateusz/gdb_printers/python')
  from libstdcxx.v6.printers import register_libstdcxx_printers
  register_libstdcxx_printers (None)
  end

Download contents of https://gcc.gnu.org/svn/gcc/trunk/libstdc++-v3/python/libstdcxx/ under:
/home/mateusz/gdb_printers/python/libstdcxx

Should work now.

Tools

• sudo ./remount_hdd.sh - mount build/hdd.vdi partitions as p1, p2, p3, p4 in current directory. Requires qemu-nbd
• objdump -f - entry point logical address
• objdump -h - elf headers
• grub-file --is-x86-multiboot2 build/kernel-x86_64.bin; echo $? - check if kernel is multiboot2 compliant, (0 means yes)