filesys: mount host directories as AmigaDOS volumes

[codewiz]

Host-filesystem support: [[filesys]] config entries export host directories to the guest as AmigaDOS volumes:

# Define HOSTFS0:
[[filesys]]
path = "/home/bernie/emu/amiga/hd/WB"
volume = "WB"   # Optional, defaults to the directory name
bootpri = 5     # Optional boot priority; default -128 = never boot

# Multiple filesystems supported
[[filesys]]
path = "/home/bernie/emu/amiga/hd/Work"

Design

A new Copperline services board (manufacturer 0x1448, product 5, 64K Zorro II, RAM-backed) carries everything guest-side, with room for future services (RTG, clipboard, ...) on the same board:

• guest/services/ -- a tiny handler in C plus an asm entry table, built with the dockerized m68k-amigaos GCC 16 (stefanreinauer/amiga-gcc:gcc-v16.1), compiled -mpcrel so the ROM is relocation-free and runs at whatever base autoconfig assigns (the Makefile fails the build if relocations or data/bss sneak in). The built ROM is committed as assets/services/services_rom.bin (~600 bytes), so a plain cargo build needs no cross-toolchain. The DiagArea is embedded in the ROM at +0x40, like real autoboot board ROMs.
• Boot: Kickstart copies the DiagArea; its DiagPoint stub jsr's back into the ROM, which traps to the emulator and mounts one DeviceNode per config entry via AddBootNode (ADNF_STARTPROC), so DOS mounts and starts the handlers at boot. Each mount's boot priority comes from a per-unit DosEnvec the emulator writes into the board window; when a HOSTFS node wins the boot vote, the DiagArea's BootPoint runs the standard autoboot sequence (FindResident("dos.library"), jsr rt_Init) and DOS mounts it as SYS:.
• Packets: the handler process is a pure pump -- WaitPort/GetMsg, one reserved A-line trap per DosPacket (D1 = packet, A1 = port), PutMsg the reply. All ACTION_* semantics live host-side in src/filesys.rs (FilesysHle, the CPU's high-level-emulation hook), which reads/writes guest memory directly.
• Volumes: at handler startup the emulator builds a DLT_VOLUME DosList node in the board window and the guest AddDosEntrys it (a dedicated trap return code -- only guest code may take the DosList semaphore). id_VolumeNode/fl_Volume point at it, which is what makes Workbench icons and C:Info work.
• DOS ABI layer: src/amigaos/dos.rs mirrors the NDK dos.h/dosextens.h constants and structures as repr(C) structs of big-endian fields (zerocopy), so the Rust definition is the guest layout and one write serializes it -- no magic offsets at call sites. Guest-visible objects (FileLocks, volume nodes) are allocated from board-window pools, so the host never calls guest AllocMem.

Path resolution follows FFS semantics, verified against the real FFS handler (a single trailing slash is the directory itself: "Prefs/" lists Prefs, "Prefs//" its parent; names are case-insensitive; an Assign: prefix in a packet name resolves relative to the supplied lock, like UAE's get_aino).

Status

Area	Feature
Mounting	Autoconfig board, DiagArea boot, AddBootNode mounts, handler autostart	✅
Mounting	Volume DosList node (Workbench icon, C:Info row)	✅
Mounting	Guest warm-reboot state reset (stale ports/locks in the emulator)	✅
Mounting	Real FileSysStartupMsg/DosEnvec, so Early Startup shows CLFS hostfs-N	✅
Mounting	bootpri config option; BootPoint boots DOS off a HOSTFS volume	✅
Mounting	ACTION_DIE dismount: volume off the DosList, handler process exits; refused with ERROR_OBJECT_IN_USE while locks or files are open (protects the boot volume). dn_Task is cleared, so the next access to the device restarts the handler and remounts the volume	✅
Info	DISK_INFO / INFO with real statvfs sizes, UAE-style block scaling	✅
Info	IS_FILESYSTEM	✅
Locks	LOCATE_OBJECT, FREE_LOCK, COPY_DIR (DupLock), PARENT, SAME_LOCK	✅
Locks	Access-mode enforcement (exclusive vs shared)	❌
Examine	EXAMINE_OBJECT, EXAMINE_NEXT (dir, list), EXAMINE_FH	✅
Examine	EXAMINE_ALL (DOS falls back to EXAMINE_NEXT)	❌
Read I/O	FINDINPUT, READ, SEEK, END, FH_FROM_LOCK, PARENT_FH, FLUSH (type, copy-from)	✅
Write I/O	FINDOUTPUT / FINDUPDATE, WRITE, SET_FILE_SIZE (all write actions refused with ERROR_DISK_WRITE_PROTECTED, and id_DiskState reports Read Only)	❌
Metadata	Protection bits, comments, and exact datestamps from UAE .uaem sidecars (+s/+p/+a; sidecars hidden from listings); host read-only maps to w-denied	✅
Metadata	SET_PROTECT (accepted and ignored; persist to .uaem once writes land)	✅
Metadata	CREATE_DIR, DELETE, RENAME, SET_DATE, SET_COMMENT	❌
Misc	Notifications, RENAME_DISK, Latin-1 filename mapping	❌

Testing

• Unit tests lock the board-window layout, the DOS struct sizes/serialization, path resolution (assign-lock prefixes), block-count scaling, and DateStamp conversion.
• Multiple HostFS volumes mount on emulated config (A1200/040 OS3.x).
• info / dir / list / type / copy all behave.
• Workbench can browse volumes and copy files to RAM:.
• Boots a production Workbench (OS 3.2, SetPatch, ENVARC: copy, WBStartup, DOpus5) directly off a host directory with bootpri = 5, and survives warm reboots.
• Dismount cycle: ACTION_DIE removes the volume and ends the handler task (watched in Scout), a later dir remounts it, and dismounting the boot volume is refused with error 202.

🤖 Generated with Claude Code - hand edited afterwards

[codewiz]

I ran out of Fable credits while testing the .uaem metadata parser.

My next goals are:

• Complete read-only functionality
• Get Workbench to boot
• Performance (ExAll, caching .uaem files...)
• Finally, write support.

[Copilot]

Pull request overview

This PR adds experimental host-filesystem support by introducing a new Copperline “services” Zorro II board and a guest-side handler ROM that forwards AmigaDOS packets to a host-side Rust HLE implementation, enabling [[filesys]] config entries to mount host directories as HOSTFS<n>: volumes.

Changes:

• Introduces a new services autoconfig board type and plumbing to pre-seed its RAM window with the handler ROM + mount/diag data.
• Adds src/filesys.rs (host-side HLE) plus an AmigaDOS ABI mirror (src/amigaos/dos.rs) and configuration parsing/validation for [[filesys]].
• Adds guest-side handler sources/build instructions and commits the built ROM artifact for normal cargo build workflows.

Reviewed changes

Copilot reviewed 14 out of 17 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/zorro.rs	Adds a services board product ID/spec and a helper to add RAM-backed boards pre-seeded with an image.
src/lib.rs	Exposes the new filesys module.
src/filesys.rs	Implements host-side AmigaDOS packet semantics for mounted host directories, plus board-window layout helpers and unit tests.
src/emulator.rs	Wires config-provided filesys mounts into the machine at build time.
src/cpu.rs	Replaces the no-op HLE handler with FilesysHle and adds a mounts setter.
src/config.rs	Adds [[filesys]] parsing, defaulting, validation, and services-board insertion into the Zorro chain.
src/amigaos/dos.rs	Adds a zerocopy-backed big-endian ABI mirror for DOS constants and structures.
src/amigaos.rs	Exposes the new amigaos::dos module.
guest/services/README.md	Documents the guest-side handler ROM purpose and rebuild process.
guest/services/Makefile	Adds dockerized m68k build pipeline and checks for relocations/data/bss.
guest/services/handler.c	Implements the guest packet-pump handler and expansion-init mounting logic.
guest/services/entry.s	Defines the entry table and embedded DiagArea used for expansion init / autoboot.
guest/services/copperline_board.h	Shares board layout/trap opcode constants between guest and host.
Cargo.toml	Adds zerocopy dependency for ABI structs.
Cargo.lock	Locks zerocopy dependency.
.gitignore	Ensures the committed services ROM artifact is not ignored; ignores guest build intermediates.

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[codewiz]

@codex review

[Copilot]

Pull request overview

Copilot reviewed 16 out of 19 changed files in this pull request and generated 4 comments.

[codewiz]

Config GUI proposal (I could push it as a separate branch and open a PR if you want to review it):

[LinuxJedi]

Fantastic work. I’ll merge it at this point and we can iterate on it in further versions