Skip to content

UAE JIT Status

Jump to bottom
akadata edited this page Feb 14, 2026 · 1 revision

UAE JIT Status (AArch64)

This page tracks the current bring-up state of the optional UAE JIT backend in pistorm64.

Current headline status:

  • JIT integration work is in progress.
  • It is not yet a stable/reliable normal runtime path.
  • Use Musashi (non-JIT) for production/regular operation.

Scope

  • This is a CPU backend integration, not a full UAE/Amiberry frontend port.
  • Goal: keep PiStorm memory/platform code (src/platforms/amiga/*, src/memory_mapped.c) and use UAE JIT only for CPU execution.

Build status

Current build path:

make USE_UAE_JIT=1 uae-jit

Opcode regeneration (CPU/JIT tables)

Opcode generation inputs now live in-tree:

  • src/uae/gen/table68k is the authoritative opcode specification input.
  • src/uae/gencpu.cpp and src/uae/jit/gencomp.cpp are the authoritative generators for cpuemu_*.cpp, cpustbl.cpp, and JIT compstbl.cpp.

To regenerate the opcode outputs, run:

make uae-opcodes

This builds the host generators under build/uae/gen/ and emits refreshed cpuemu_*.cpp, cpustbl.cpp, and cputbl.h in src/uae/, plus compemu.cpp, compstbl.cpp, and comptbl.h in src/uae/jit/.

Notes:

  • uae-jit is incremental. It rebuilds only changed files and then links emulator if needed.
  • If link state looks stale, run:
make clean
make USE_UAE_JIT=1 uae-jit

Confirmed working pieces

  • build/uae/libuae.a is built and linked.
  • UAE bridge/stub objects are linked from source (src/uae/pistorm_uae_bridge.cc, src/uae/pistorm_uae_stubs.cc).
  • Reset vector read is now observed as valid in JIT mode:
    • Read PC from address 4 : 0x00F800D2
    • [UAE] reset vectors: SP=11144EF9 PC=00F800D2
  • JIT starts and allocates translation cache:
    • Actual translation cache size : 32768 KB
  • m68k_pc_indirect now reports enabled in JIT path:
    • [Core1] Emulation mode 1 m68k_pc_indirect 1

Known runtime issues (current)

  1. OVL:0 appears shortly after startup and execution does not yet progress to a stable Workbench boot under JIT.
  2. Z2 autoconfig probing under JIT produces high-volume warnings like:
    • Unexpected WORD read from Z2 autoconf addr ...
  3. 68060 is not accepted by current parser/tables and falls back:
    • Invalid CPU type 68060 specified, defaulting to 68000.
  4. BAD JIT opcodes list entries (e.g. DIVL, SUBX) are expected fallback markers, not by themselves a fatal error.

Memory map rules for this bring-up

  • Chip RAM lives on the Amiga side (Agnus/8372A). Do not map Pi-side RAM as chip RAM unless you are explicitly faking it for controlled tests.
  • Do not place "chipram" at $00C00000 for this path.
  • Keep Kickstart ROM at $00F80000 and let reset overlay force vectors at low memory during reset.
  • $00C00000 is trapdoor/slow expansion territory on A500-class mapping, not primary chip RAM.

Source parity notes (Z3660_emu vs Amiberry/WinUAE)

  • Reference source: Z3660_emu (from z3660/.../Z3660_emu/src/uae) is the canonical reference set for this integration. Our src/uae tree matches that file list exactly.
  • Amiberry/WinUAE extras: Amiberry ships additional CPU emulation tables and helpers (cpuemu_20..35, cpuemu_50, cpummu*.cpp, cpu_thread.cpp, cpuboard.cpp, etc.) that are not present in Z3660_emu. These are not required for the current JIT bring-up path, but should be evaluated if we decide to expand beyond the Z3660_emu feature envelope.
  • A9/Z-TURN features: Z-TURN platform specifics (e.g. A9 GIC, XGpioPs, Zynq MMU wiring) must remain excluded from PiStorm64. Keep the UAE core free of those platform dependencies and continue to route all bus/memory via the PiStorm bridge.

Current recommended test run

PISTORM_ENABLE_QUEUE=0 ./emulator --jit

If the system drops to OVL:0 too early (yellow screen flashing white) try delaying the first overlay drop with:

PISTORM_UAE_OVL_HOLDOFF=1 PISTORM_ENABLE_QUEUE=0 ./emulator --jit

Increase the holdoff count if needed (each count defers one OVL:0 request).

Keep initial tests minimal (ROM + chipram + platform) before re-adding Z2/Z3, RTG, PiSCSI, and A314 one by one.

Next debugging targets

  1. Keep overlay/vector path forced before m68k_reset_newcpu() and verify no post-reset path drops to low unmapped fetch.
  2. Make Z2/Z3 autoconfig handlers fully tolerant of JIT word/long accesses.
  3. Reduce autoconfig warning noise to debug-level once width handling is robust.
  4. Re-introduce platform devices incrementally and capture first failing add-on.

Clone this wiki locally