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universalisos/universalisos_status_report.md

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UniversalisOS — Current Status Report

Audit date: 2026-07-09 | Source: full codebase scan + build verification

Build Status

Target Command Result
ARMv7 / QEMU virt make ARCH=armv7 PLATFORM=qemu-arm-virt ✅ BUILDS (65 objects, 172 KB text)
RISC-V / PolarFire make ARCH=riscv PLATFORM=polarfire ✅ BUILDS (23 objects, 20 KB text)
AArch64 / QEMU virt make ARCH=aarch64 PLATFORM=qemu-aarch64-virt ❌ FAILS (fdt_reader.h missing)

Codebase Metrics

Component Lines of Code Files
Core kernel (src/core/) 14,129 32 files + 7 subdirs
ARMv7 arch (src/arch/armv7/) 3,390 13 files + 3 subdirs
AArch64 arch (src/arch/aarch64/) 389 9 files
RISC-V arch (src/arch/riscv/) 5,181 28 files + 1 subdir
Shared platform drivers (src/platform/drivers/) 15,572 24 files
Total ~41,790

Architecture Track Parity

1. ARMv7 / QEMU virt — 🟢 MATURE (the reference track)

This is the most complete track. The core kernel lives in src/core/ and is compiled ONLY for this arch (RISC-V and AArch64 are self-contained).

Subsystem Status Key Files
Boot + exception vectors ✅ Complete boot.S, exceptions.cpp
ARMv7 MMU (S1, flat 4GB map) ✅ Complete mm.cpp
GICv2 interrupt controller ✅ Complete gic.cpp
Context switching (full register save/restore) ✅ Complete context_switch_asm.S
Cooperative + preemptive scheduler ✅ Complete scheduler.cpp, sched_core.cpp
VMIT XML config parser ✅ Complete cfg_parser.cpp, sysmodel.h
ARINC 653 sampling IPC ✅ Complete uos_ipc_core.cpp
ARINC 653 queuing IPC ✅ Complete uos_queuing.cpp
Shared memory + events ✅ Complete uos_shmem.cpp
seL4-style capability MDB ✅ Complete cap.cpp, cap_compiler.cpp
3-tier health monitoring ✅ Complete uos_hm.cpp
Guest ABI (PV Linux ABI) ✅ Complete uos_pv_abi.cpp
PikeOS-class syscalls (task, TLS, ExRegs) ✅ Complete uos_syscalls.cpp
Partitions + VM contexts ✅ Complete partition.cpp, vm.cpp
MMU walk + address space ✅ Complete uos_mmu_walk.cpp, uos_adspace.cpp
FPU context save/restore ✅ Complete uos_fpu.cpp
SMP framework ✅ Framework uos_smp.cpp
Device drivers ✅ Complete PCI/PCIe, USB (EHCI), block, network, GPIO, I2C, SPI, UART, timer, framebuffer

Verdict: ~60–70% of PikeOS kernel-core layer, ~5–10% of system-software layer. This matches the plan's assessment.

2. AArch64 / QEMU virt — 🟡 MP0 BRING-UP (early)

Warning

Build is BROKEN — fdt_reader.h referenced in kernel_aarch64.cpp does not exist anywhere in the tree.

Subsystem Status Notes
EL2 boot + EL3→EL2 drop ✅ Complete boot.S (67 lines) — QEMU hands EL2
Exception vector table (VBAR_EL2) ✅ Complete exceptions.S (2.5 KB)
EL2 trap handler (sync abort) ✅ Stub el2_trap.cpp — prints ESR then halts
LPAE S1 MMU (identity map) ✅ Complete mmu_lpae.cpp — Bao-proven constants, L0→L1 1GiB blocks
UART (PL011 direct) ✅ Inline Hardcoded in kernel_aarch64.cpp (not abstracted)
FDT reader ❌ MISSING fdt_reader.h / fdt_reader.cpp do not exist
GICv3 ❌ Not started
Stage-2 MMU (VTTBR_EL2) ❌ Not started
vCPU context / ERET ❌ Not started
Virtual timer (CNTVOFF) ❌ Not started
Scheduler ❌ Not started
IPC ❌ Not started

Verdict: ~15% of MP0 is done. The EL2 entry + LPAE flat map is proven but everything beyond that is TODO. The kernel_aarch64.cpp is explicitly marked as "TEMPORARY harness" to be replaced once the real subsystems are ported.

3. RISC-V / PolarFire — 🟢 FUNCTIONAL (parallel agent track)

Self-contained under src/arch/riscv/ (does NOT use any src/core/ files).

Subsystem Status Key Files
Boot (S-mode, multi-HART) ✅ Complete boot.S (6.9 KB)
UART (MMUART/NS16550) ✅ Complete uart.cpp
Exception/trap handling ✅ Complete trap.S + uos_trap.S (14 KB combined)
PLIC (interrupt controller) ✅ Complete plic.cpp (4.5 KB)
Timer (mtime/mtimecmp) ✅ Complete timer.cpp
Sv39 page tables ✅ Complete page_table.cpp
Context switching ✅ Complete context_switch_asm.S
PikeOS-style scheduler (time partitions) ✅ Complete task_sched.cpp (13 KB)
Partition management ✅ Complete vm.cpp (8.6 KB)
SBI interface ✅ Complete sbi.cpp
Hypercalls (ecall ABI) ✅ Complete hypercall.cpp (6.2 KB)
Guest loading ✅ Complete guest_loader.cpp
Health monitoring ✅ Complete hm.cpp
SMP (secondary HART wake) ✅ Framework smp.cpp
Bao-style VMM ✅ Complete uos_vmm.cpp, uos_vm.cpp
CPU/emulation ✅ Complete uos_cpu.cpp, uos_emul.cpp

Verdict: RISC-V has its own scheduler, partitions, VMM, hypercalls, and page tables. Independently functional but doesn't share the ARMv7 core subsystems (no ARINC IPC, no cap MDB, no HM 3-tier). This is by design — it's the parallel-agent track you mentioned.

Plan Milestone Status (MP0–MP5)

Milestone Description Status Details
MP0 AArch64/EL2 foundation (LPAE S1, DTB, QEMU cortex-a53 gate) 🟡 ~30% EL2 entry + boot ✅, exception vectors ✅, LPAE S1 flat map ✅, UART ✅. Missing: FDT reader (build broken), GICv3 init, timer, scheduler wiring. The "QEMU gate" test cannot run because the build is broken.
MP1 Hardware virtualization (Stage-2, GICv3 VGIC, vCPU ERET, virtual timer) ❌ Not started No Stage-2 page tables (VTTBR_EL2). No GICv3 at all. No vCPU struct.
MP2 i.MX 8M Plus + STM32MP257 + i.MX6 platform ports 🟡 Scaffolding only qemu-aarch64-virt platform exists. zybo (Zynq-7010) platform exists with its own linker script. No i.MX or STM32MP platform dirs yet.
MP3 Linux guest via Yocto ❌ Not started Depends on MP1 + MP2.
MP4 M33 TrustZone-M / M7 MPU + RPMsg ❌ Not started
MP5 SMP 🟡 Framework uos_smp.cpp exists for ARMv7. RISC-V has smp.cpp with secondary HART wake. Neither is a full SMP scheduler.

Platform Ports

Platform Arch Status Key Config
qemu-arm-virt ARMv7 ✅ Builds + runs Cortex-A15, GICv2, PL011
qemu-aarch64-virt AArch64 ❌ Build broken Cortex-A53, EL2, PL011
qemu-riscv-virt RISC-V ⚪ Scaffold only Empty platform.mk
qemu-riscv64-virt RISC-V ⚪ Scaffold only Empty dir
polarfire RISC-V ✅ Builds PolarFire Icicle Kit (parallel track)
polarfire-soc RISC-V ⚪ Scaffold only Empty dir
zybo ARMv7 ✅ Configured Zynq-7010, Cortex-A9, custom linker

Build System Health

The Bao-style Makefile is solid and well-designed:

  • ✅ Per (ARCH, PLATFORM) isolated build trees (build/armv7/qemu-arm-virt/, build/riscv/polarfire/, etc.)
  • ✅ cpu-skip-y mechanism for platform driver substitution
  • ✅ drv-objs-y opt-in for shared drivers (ARMv7 uses them; RISC-V/AArch64 skip them)
  • ✅ UOS_LDSCRIPT override per platform
  • ✅ UOS_CPU override per platform (zybo → cortex-a9)
  • ✅ clean per-target, clean-all for everything

What the "60–70% kernel-core / 5–10% system-software" Verdict Means

✅ What EXISTS (~60–70% of kernel core)

  1. Boot + MMU + exception handling (ARMv7 + RISC-V proven)
  2. Cooperative + preemptive scheduler with ARINC 653 time partitions
  3. ARINC 653 IPC: sampling ports, queuing ports, shared memory, events
  4. seL4-style capability system with derivation tree (MDB)
  5. 3-tier health monitoring (PAC/MultiMAC/ModuleMAC)
  6. PV guest ABI (hypercall path 0xA0–0xAF)
  7. PikeOS-class syscalls (task lifecycle, TLS, ExRegs, attributes)
  8. Full device driver suite (PCI/PCIe, USB EHCI, block, network, GPIO, I2C, SPI)
  9. VMIT XML configuration parser

❌ What's MISSING (~5–10% system software + ~30% kernel features)

  1. No hardware-assisted virtualization — no Stage-2 (VTTBR), no GICv3 VGIC, no vCPU ERET
  2. No personalities — no APEX/POSIX/Linux/Ada/Android SSW partitions
  3. No host tooling — no Eclipse integration, no VMIT IDE, no debugger stubs
  4. No certified file systems (PikeOS ships DDC-I Deos FS, FATFS, JFFS2)
  5. No network stack (PikeOS ships lwIP, a full TCP/IP personality)
  6. No AArch64 subsystems beyond boot+MMU (the MP1–MP5 gap)
  7. No real Linux guest boot — the PV ABI exists but no actual kernel loading path

Immediate Blockers

# Blocker Impact Fix
1 fdt_reader.h missing AArch64 build broken Create a minimal FDT reader, or remove the #include if DTB parsing isn't needed yet
2 ARMv7 linker warning: cannot find entry symbol _start Boot entry might be wrong Add ENTRY(_start) to linker.ld or rename the entry symbol
3 20 MB BSS in ARMv7 build Huge ELF, wastes QEMU RAM Reduce static allocations (e.g. vm_page_tables[16][4096] in mm.cpp)