QEMU error "Could not locate UDIF trailer" when using custom boot.dmg (Windows/AMD)

[LSXAxeller]

Operating system

Windows 11

Description

I am trying to install macOS 14 (Sonoma) on a Windows 11 machine with an AMD Ryzen processor. I am attempting to use a local installation image by mounting it as /boot.dmg as described in the documentation, but QEMU fails to read the file structure.

The DMG image used in the installation was built from the GitHub Actions run at https://github.com/LSXAxeller/macos-iso-builder/actions/runs/19634577669, using the workflow available at https://github.com/LongQT-sea/macos-iso-builder.

Environment:

• Host OS: Windows 11 (24H2)
• Backend: Docker Desktop (WSL2)
• CPU: AMD Ryzen 5 7600

Docker compose

services:
  macos:
    image: dockurr/macos
    container_name: macos
    environment:
      VERSION: "14"
      RAM_SIZE: "24G"
      CPU_CORES: "1"
      DISK_SIZE: "64G"
    devices:
      - /dev/kvm
      - /dev/net/tun
    cap_add:
      - NET_ADMIN
    ports:
      - 8006:8006
      - 5900:5900/tcp
      - 5900:5900/udp
    volumes:
      - ./macos:/storage
      - "D:\\Programs\\Pro\\ISO\\macOS_Sonoma_14.8.2.dmg:/boot.dmg" 
    restart: always
    stop_grace_period: 2m

Docker log

❯ Starting macOS for Docker v2.29...

❯ For support visit https://github.com/dockur/macos⁠

❯ CPU: AMD Ryzen 5 7600 | RAM: 30/31 GB | DISK: 26 GB (v9fs) | KERNEL: 6.6.87.2-microsoft-standard-WSL2...


❯ Building boot image...

❯ 

❯ Model: iMacPro1,1

❯ Rom: 0016cb3c9171

❯ Serial: C02G5SYYHX87

❯ Board: C02131270CDJG361M

❯ 

❯ Booting macOS using QEMU v10.0.6...

qemu-system-x86_64: -drive file=/storage/14/base.dmg,id=InstallMedia,format=dmg,cache=unsafe,readonly=on,if=none: Could not locate UDIF trailer in dmg file

Screenshots (optional)

No response

[123wjr]

I face the same situation, but with MacOS 15 built by https://github.com/Comp-Labs/Download-macOS

[LongQT-sea]

Try rename the .dmg image to .iso

Btw, on Windows host, you should use OC4VM if you want to run a macOS VM.

Running macOS inside Docker, inside a WSL2 aka a VM inside the Windows hypervisor is slow.

[123wjr]

Try rename the .dmg image to .iso

@LongQT-sea
It was built as the dmg file instead of the iso file, I wonder whether a simple rename instead of rebuild could work or not.
Also the file type needed is declared in the line below.

macos/src/install.sh

Line 16 in 2977141

BASE_IMG="$STORAGE/base.dmg"

It seems that wsl2 is on the same level which windows is on, so what makes the differences?

[LSXAxeller]

@LongQT-sea Already running it using OC4VM, but due unsupported GPU (RTX 4060 TI) there's no HW Acceleration, I mainly installed it to test macOS variant from a Cross-Platform I develop, but event starting it up is crashing without HW Acceleration, so I tried to install the docker version hoping to see some difference.

and renaming the image to .iso is just copying it again to .dmg.

[LongQT-sea]

Anything that need hardware 3D acceleration like your use case need passthrough of a supported Intel iGPU or dGPU, OC4VM and macOS inside Docker are not supported.

About the macOS iso and dmg image:

# ISO image:
#   - A proper UDF DVD/CD format image (mountable in Windows).
#   - Intended for virtual machine use; attach as a virtual CD/DVD drive.
#   - Compatible with Proxmox VE, QEMU, VirtualBox, and VMware.
#
# DMG image:
#   - Raw disk image with GUID Partition Table, this is mandatory so it can be flash to a USB drive using Rufus (Windows).
#   - Can also be used with virtual machines, but must be attached as a virtual hard disk.
#   - Most VMM require convert the .dmg image to a compatible virtual disk format using qemu-img,
#       e.g. convert to .vhd for Hyper-V or .vmdk for VMware. QEMU can use raw disk image without conversion.