vmix.nix/lib/images/macos/README.md
Git Sagar 8dc8f4265d macOS: drive the install and all customization from a Recovery "PE", no GUI
Replace the screenshot/OCR/keystroke driving of Apple's Recovery with a
"PE": BaseSystem.dmg (a journaled HFS+ volume, writable from Linux) with one
LaunchDaemon added (makeRecoveryPE) that runs /Volumes/VMIX/run.sh as root at
boot, records the status and powers off. launchd loads it alongside its signed
cache (verified on Tahoe 26.6.2); same idea as AutoNBI/Imagr NetBoot images.

- makeImage: the PE runs vmix-install.sh (erase, installer app, SharedSupport
  pkgdmg, startosinstall). Progress is read from the serial console
  (boot-args serial=3 -v, VMIX-* markers) and screenshots (brightness only).
  Fully offline; prepare now takes ~5 min instead of ~10.
- customizeImage: boots the PE with the image attached and runs the template
  offline against the mounted System/Data volumes; OpenCore ScanPolicy
  restricted to HFS+/SATA so only the PE can boot. One PE boot ~30 s. The
  installed macOS is never booted for customization, so nothing depends on
  launchd/BTM approval or a first-boot agent (removed).
- templates rewritten for offline use: generalize creates the user with
  dscl -f (admin, home, auto-login kcpassword, Setup Assistant suppression,
  hostname, locale, timezone, keyboard type, container resize); remote-access,
  no-updates, performance edit the target's plists.
- makeBootDisk: build-time OpenCore variant (serial console, ScanPolicy).
- vm-driver.py rewritten: passive observation only (serial markers, kernel
  boots, panics, brightness), disk+serial-aware hang watchdog, reboot-death
  reset, halt/loginwindow detection. No OCR/tesseract.
- OpenCore: four SMBIOS DIMMs for MacPro7,1 (no "Memory Modules
  Misconfigured" warning).
- tools/soak.sh: repeatability harness.

Verified on daku: base install 23 min end to end; basic + generalize in three
~30 s PE boots; the result auto-logs into the desktop with the created user.

Root cause of the "first-boot hang" (from the serial log): the guest's restart
path panics (IOPlatformHaltRestartAction -> AppleSMC, SMCWDT smcWriteKey
kSMCBadCommand, nested panic) because the pinned OSX-KVM Lilu disables itself
on macOS 26, so VirtualSMC never loads. Handled by the driver (reset within
60 s); kext update to follow.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XsESshRCoBoUVWV9qKURUF
2026-09-10 13:33:38 -03:00

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# macOS images (Tahoe 26)
Pre-installed, Apple-ID-capable macOS VM images built the same way as the
Windows ones: `makeImage` (unattended install) → templates → `.generalize`
(user, hostname, fresh SMBIOS identity). Runs on QEMU/KVM with OpenCore.
```
vmix build --image macos.images.tahoe.basic --generalize username=sagar,password=secret,hostname=MAC
vmix run ./result --macos --vnc :10 --mem 8192
```
Nix: `macos.images.tahoe.{pe,upstream,basic,remote}` and
`<image>.generalize { username; password; hostname; timezone; locale; seed; … }`.
## How it works: the vmix "PE"
Apple's Recovery (`BaseSystem.dmg`, a plain journaled HFS+ volume) with **one
LaunchDaemon added** (`makeRecoveryPE`): at boot it mounts a `VMIX` volume and
runs `run.sh` from it as root, records the exit status and powers off. That is
the whole automation surface — the equivalent of Windows PE + Autounattend:
* **no GUI is driven**: no OCR, no keystrokes, no screen layouts to learn per
macOS version; the hook is a launchd plist, stable across releases (same idea
as AutoNBI/Imagr NetBoot images).
* **observable**: the guest prints `VMIX-*` markers to `/dev/console`, which the
build reads from QEMU's serial log (`boot-args serial=3 -v`). Kernel panics and
reboots show up there too. Screenshots are still taken for debugging.
* **offline**: no NIC during the install, and the guest blackholes Apple's
install/verify endpoints so `startosinstall` never waits on the network. The
only inputs are the pinned `InstallAssistant.pkg` and `BaseSystem.dmg`.
* **everything else happens offline from the PE too**: templates and generalize
mount the image's Data volume (rw) and System volume (ro) and edit them
(`dscl -f` for users, `plutil` for preferences) — the installed macOS is
never booted for customization, so nothing depends on launchd/BTM approval,
first-boot agents or auto-login inside the guest. One PE boot ≈ 30 s.
### Pipeline
1. `makeRecoveryPE` — BaseSystem.dmg → raw HFS+ image + `ch.vmix.pe` daemon.
2. `makeImage` — QEMU with: OpenCore boot disk (build variant with serial
console), the PE, the empty target disk, the VMIX volume (`vmix-install.sh`,
installer app skeleton) and the whole `InstallAssistant.pkg` mapped as a raw
disk. The guest script erases the target as APFS, unpacks the app and `dd`s
the pkg into it as `SharedSupport.dmg` (it is a "pkgdmg": xar + koly footer;
the bare xar member fails with "pkgdmg is missing a footer"), then runs
`startosinstall`, which reboots itself through the install phases. The
installed system's first boot ends at the loginwindow: the driver detects the
bright screen and powers the VM down. OpenCore is then copied into the image's
own ESP so it boots with plain OVMF.
3. `customizeImage` — boots the PE with the image attached (OpenCore
`ScanPolicy` restricted to HFS+ on SATA, so only the PE can boot) and runs the
template script with `$SYS`/`$DATA` mounted. `pe-lib.sh` has the helpers.
4. `templates/generalize.nix` — user (dscl, admin, home from the user template),
auto-login (`kcpassword`), Setup Assistant suppression, hostname, locale,
timezone, keyboard type, container resize, fresh SMBIOS via a new OpenCore
ESP (`serial`/`mlb` from macserial, MAC + UUID from `seed`).
### Recovery source
`recovery.file` in `upstream.json` points at a content-addressed store path for
the verified Tahoe `BaseSystem.dmg` (Apple's CDN load-balances Sequoia/Tahoe
during the rollout, so a plain fetch is non-deterministic). Reproduce it on any
host with `nix store add-path --name macos-tahoe-BaseSystem.dmg BaseSystem.dmg`.
Drop `recovery.file` to fetch from Apple instead (`fetchRecovery` retries until
the pinned hash matches).
## Reliability
Things QEMU does intermittently, and what handles each (all in `vm-driver.py`
and `vmix-install.sh`; every event is logged with a reason):
* `startosinstall` prepare stalls or crawls — the guest kills and retries it on a
freshly erased target (free-space watchdog + time cap).
* the installer comes back to the PE instead of the install phase — the PE
counts boots and simply re-runs the install (max 3).
* the installed system hangs at the Apple logo on first boot — a `system_reset`
is issued only when the screen is dark and frozen **and** disk and serial
console are idle, so a slow-but-working boot is never interrupted.
* macOS `shutdown -h` halts to a black screen without an ACPI power-off — an
idle black screen counts as a completed halt.
* a kernel panic (seen on the serial console) resets the VM.
* a wedged run fails at the 4 h timeout instead of hanging.
`tools/soak.sh <flake> macos.images.tahoe.upstream 3` rebuilds an image N
times and tabulates outcome, duration, boots, resets, panics and retries.
## Debugging
`/tmp/vmix-macos/<name>/` on the build host: `driver.log`, `serial.log`
(kernel + `VMIX-*` markers), periodic PNG screenshots, `qmp.sock`.
`vmix-run.log` / `system-install.log` from the VMIX volume are printed at the
end of the build. Add `vncDisplay = ":10"` to watch.
## QEMU profile
`helpers/qemu.nix`: q35, `Skylake-Client` CPU spoof (works on AMD),
AppleSMC with the OSK, XHCI keyboard/tablet, AHCI disks, VMware SVGA,
virtio-net pinned to `PciRoot(0x0)/Pci(0x12,0x0)` so OpenCore marks it built-in
(en0, required for Apple ID / iMessage). SMBIOS `MacPro7,1` with four DIMMs
described (avoids the "Memory Modules Misconfigured" warning).