This is also interesting. So what is your ultimate goal for this? I.e what features of R4R do you plan to provide to demonstrate this?
The ultimate goal of R4R is to demonstrate, in a tangible and observable way, how all four Intel x86 protection rings (0–3) can coexist and interact within a single operating system — each with its own stack, TSS, LDT, and clearly defined domain.
While most modern systems only use Ring 0 and Ring 3 for simplicity, R4R aims to revive Intel’s original privilege model and show how segmentation, paging, and call gates can be combined to create real hardware-enforced isolation — not just software-level separation.
The main features that demonstrate this are:
Independent initialization of all four rings, each running its own “mili-kernel” (Core, Devs, Libs, Users).
Hardware-managed transitions using call gates and task gates (no software traps).
Per-ring TSS and LDT, showing that every ring can maintain its own execution context and memory space.
System calls implemented purely through call gates, demonstrating cross-ring communication without stack argument passing.
A static paging layout combined with segment-based isolation, proving that segmentation still works perfectly when properly configured.
In short, R4R’s goal is educational and architectural:
to prove that the x86 protection model — often dismissed as obsolete — is in fact coherent, elegant, and fully functional when used as intended.
Future versions (0.01+) will extend this with a ring-aware scheduler, interrupt handling, and message-passing between rings to illustrate real multi-domain operation.
. I still tend to disassemble with intel one (objdump/gdb/ida..) but less so.
