JOS - Jakob's OS

Experimental busy dad's learning activity.

Rough list of features

• ✅ use Rust instead of C
• ✅ interrupts (time, keyboard)
• ✅ paging
• ✅ heap memory
• ✅ higher half kernel
• ✅ userspace (ring 3) programs
• ✅ multiprocessing with simple scheduler
• ✅ syscalls with userspace libc in Rust and C
• ✅ VGA mode
• ✅ "fake file operations" (read files embedded in executable)
• ✅ run Doom
• ✅ use High Precision Event Timer CPU feature to get nanosecond resolution timestamps
• ✅ colored logging
• ✅ pretty logo
• enable userspace processes to communicate via an IPC
• network stack
• make running on RISC-V (ESP32-C3?) additionally to x86_64

Rough list of ecosystem

• ✅ Github CI action to build
• ✅ gdb debugging
• adopt Bazel instead of make

Compile and Run

• docker build buildenv_rust -t jos_buildenv
• docker run --rm -it -v "${pwd}:/root/env" jos_buildenv
• make build-x86_64
• (other shell) qemu-system-x86_64 -no-reboot -cdrom dist/x86_64/kernel.iso

https://wiki.osdev.org/QEMU#Useful_QEMU_command-line_options

Reverse Debugging via qemu

(couldn't get this working yet)

https://www.qemu.org/docs/master/system/replay.html

• qemu-img create -f qcow2 empty.qcow2 1G
• qemu-system-x86_64 -s -S -d int,cpu_reset,guest_errors -action panic=pause -no-reboot -monitor stdio -cdrom dist/x86_64/kernel.iso -icount shift=auto,rr=record,rrfile=record.bin,rrsnapshot=init -net none -drive file=empty.qcow2,if=none,id=rr
• savevm TAG (multiple times if needed)
• quit
• qemu-system-x86_64 -s -S -d int,cpu_reset,guest_errors -action panic=pause -no-reboot -monitor stdio -cdrom dist/x86_64/kernel.iso -icount shift=auto,rr=replay,rrfile=record.bin,rrsnapshot=init -net none -drive file=empty.qcow2,if=none,id=rr
• loadvm TAG

Kudos

Bootstrapped by "Write Your Own 64-bit Operating System Kernel From Scratch" by https://github.com/davidcallanan/os-series