A Model Context Protocol server for driving AmigaOS 4.1 machines — both QEMU guests and real PowerPC hardware — from MCP-aware clients such as Claude Code, Claude Desktop, and IDE plugins.

At a glance
Brings AmigaOS 4.1 inside your AI client. From a single MCP session you can:

• Browse and edit files on the target Amiga, run AmigaDOS commands with captured stdout, upload large binaries with zlib compression and resumable chunks.
• Inspect live state — running tasks, opened libraries, mounted volumes, public screens, the last alert (decoded), CPU + cache + AttnFlags.
• Drive QEMU lifecycle — start, stop, screenshot the framebuffer, save / restore VM snapshots, attach a GDB stub for whole-system debug.
• Coordinate a fleet — run one method across any mix of QEMU guests and real hardware in parallel; barrier, quorum, or cross-target file relay.
• Install AmigaOS 4.1 FE end-to-end onto a blank volume — preflight, ISO mount, copy, LHA extract, Kicklayout patch, verify — via a single installer.run call.
• Live X5000 hardware introspection — board / CPU temperatures, voltages, fan PWM/RPM via the Cyrus MCU, plus CCSR registers, TLB walks, and IDebug-driven per-task crash snapshots.

Pegasos II Firmware
A clean-room reimplementation of the BIOS / OpenFirmware-style boot ROM for the Pegasos II PowerPC motherboard. It boots AmigaOS 4, is ready to extend to MorphOS and Linux, and runs on the QEMU pegasos2 machine with real hardware to follow.

The original firmware (bPlan/CodeGen SmartFirmware 1.2, 2004) is nineteen years out of date and has known defects with modern PCI expansion cards. This rewrite is built fresh from public specs + the original SmartFirmware source license; it is not a binary patch of the stock ROM.

balaton wrote:@derfs
I don't understand that explanation. Can you explain it or is it just what the AI generated? The sm501 has the whole vram memory mapped and you can certainly read and write it on both amigaone and pegasos2 so this should fundamentally work. If it doesn't there must be some other reason but I don't understand what.

Using legacy virtio devices is not recommended because they may be dropped in next release or soon after. You should really fix the driver to work with modern virtio.

One thing that modern virtio is different from legacy is that it's always little endian so more than byte access may need endian conversion. Is that handled in your driver? But if it works on pegasos2 it probably does. While the Marvell and Articia may have bits to do endian swap they are not emulated, you should get a log message with -d unimp,guest_errors if you try to use it. So the driver needs to handle it.

Both machines use the same virtio-scsi-pci device which exposes two config paths- I/O ports on BAR0, and modern MMIO capabilities on memory BARs. We pick the path at runtime with a probe, enable PCI memory+bus-master, write ACKNOWLEDGE to common-cfg STATUS, read it back. Match -> modern MMIO, else mismatch -> legacy I/O.

Pegasos2 / Sam460 (MV64361 bridge)
Transparent bridge, forwards CPU memory cycles to device BARs. Probe passes -> modern MMIO using stwbrx/lwbrx inline asm for LEBE. Must use bar->BaseAddress (CPU-visible), not bar->Physical (PCI-bus).

AmigaOne (Articia S bridge)
"floating buffer" bridge, MMIO reads return 0, writes silently dropped. Probe fails -> legacy I/O ports on BAR0 via InByte/OutByte. No software workaround for MMIO. The bridge hardware itself doesn't forward.

Why different?
Pure PCI host-bridge hardware limitation on AmigaOne machine - not QEMU, not AmigaOS. Legacy port I/O uses a separate address space the Articia S does forward, so it's the only path that works there.

Additionally, for the disk image to work, it must already be initialized. Otherwise, the Virtio SCSI driver causes a crash.

Boot Drive Support
VirtIO SCSI disks can now be used as boot drives.

virtioscsi.device - VirtIO SCSI Device Driver for AmigaOS 4.1 FE
Version 1.8 - 11 April 2026
Author: derfs
Source: https://github.com/derfsss/VirtualSCSIDevice

v1.8 (11.04.2026)
- Unified platform: single -device virtio-scsi-pci works on all QEMU machines (AmigaOne, Pegasos2, SAM460ex). MMIO probe auto-detects transport at boot. Tested on all three machines.
- Performance: cacheable bounce buffers with CopyMem + CacheClearE (~10-20x faster for <=64KB I/O). O(1) cross-unit cookie routing. ISR occupancy bitmask skips inactive units.
- Debug: error-path instrumentation across all command handlers.
- Build: fixed header guard collision.