macosvm allow-listed by macOS for arm64. Note that the directory 'Parallels' is still used when using macosvm just so that scripts know where to find the VM and friends.
An Xcode .xip - you can get this from Apple's developer website, although you'll need to sign in first: https://developer.apple.com/downloads
If you are doing this from a local macos box, you can skip to the "update the macos host" step.
An Xcode Command Line Tools installer

Instructions (ARM64)

Go to https://dev.azure.com/vcpkg/public/_settings/agentqueues , pick the current osx queue, and delete one of the agents that are idle.
Go to that machine in the KVM. (Passwords are stored as secrets in the CPP_GITHUB\vcpkg\vcpkgmm-passwords key vault)
Update the macos host

(Once only) install macosvm to ~ (this tarball is also backed up in our vcpkg-image-minting storage account). For example from a dev workstation:

ssh vcpkg@HOSTMACHINE
curl -L -o macosvm-0.2-2-arm64-darwin21.tar.gz https://github.com/s-u/macosvm/releases/download/0.2-2/macosvm-0.2-2-arm64-darwin21.tar.gz
tar xvf macosvm-0.2-2-arm64-darwin21.tar.gz
rm macosvm-0.2-2-arm64-darwin21.tar.gz
exit

Download the matching .ipsw for the macOS copy to install. See https://mrmacintosh.com/apple-silicon-m1-full-macos-restore-ipsw-firmware-files-database/ ; links there to find the .ipsw. Example: https://updates.cdn-apple.com/2025FallFCS/fullrestores/093-37399/E144C918-CF99-4BBC-B1D0-3E739B9A3F2D/UniversalMac_26.2_25C56_Restore.ipsw
Determine the VM name using the form "vcpkg-osx--arm64", for example "vcpkg-osx-2026-01-12-arm64".

Open a terminal and run the following commands to create the VM with vcpkg-osx-2026-01-12-arm64 and UniversalMac_26.2_25C56_Restore.ipsw replaced as appropriate. This must be run in the KVM as it uses a GUI:

mkdir -p ~/Parallels/vcpkg-osx-2026-01-12-arm64
cd ~/Parallels/vcpkg-osx-2026-01-12-arm64
~/macosvm --disk disk.img,size=500g --aux aux.img -c 8 -r 12g --restore ~/UniversalMac_26.2_25C56_Restore.ipsw ./vm.json
~/macosvm -g ./vm.json

Follow prompts as you would on real hardware.
- Set up as new.
- Account name: vcpkg
- A very similar password
- Do not allow computer account password to be reset with your Apple Account.
- Apple ID: 'Set Up Later' / Skip
- No location services
- Yes send crash reports
- Set up screen time later
- Only download updates automatically
Set the desktop wallpaper to a fixed color from Settings -> Wallpaper . (This makes the KVM a lot easier to use :) )
Disable automatic updates in the VM: Settings -> General -> Automatic Updates -> Disable them all
Enable remote login in the VM: Settings -> General -> Sharing -> Remote Login

Set the vcpkg user to be able to use sudo without a password, and install Xcode. For example from a dev workstation:

scp path/to/Xcode.xip vcpkg@HOSTMACHINE:/Users/vcpkg/Xcode.xip
ssh vcpkg@HOSTMACHINE
rm ~/.ssh/known_hosts
scp Xcode.xip vcpkg@vcpkgs-Virtual-Machine.local:/Users/vcpkg/Xcode.xip
ssh vcpkg@vcpkgs-Virtual-Machine.local
printf 'vcpkg\tALL=(ALL)\tNOPASSWD:\tALL\n' | sudo tee -a '/etc/sudoers.d/vcpkg'
sudo chmod 0440 '/etc/sudoers.d/vcpkg'
sudo mdutil -ad
xip --expand Xcode.xip
sudo mv Xcode.app /Applications/Xcode.app
rm Xcode.xip
exit

Open Xcode from Applications in the guest GUI. Uncheck the "code completion model" and accept the EULA.
Update the Azure Agent URI in setup-box.sh to the current version. You can find this by going to the agent pool, selecting "New agent", picking macOS, and copying the link. For example https://download.agent.dev.azure.com/agent/4.266.2/vsts-agent-osx-arm64-4.266.2.tar.gz

Copy setup-box.sh and the xcode installer renamed to 'clt.dmg' to the host. For example from a dev workstation:

scp ./setup-guest.sh vcpkg@HOSTMACHINE:/Users/vcpkg
scp ./setup-box.sh vcpkg@HOSTMACHINE:/Users/vcpkg
scp path/to/console/tools.dmg vcpkg@HOSTMACHINE:/Users/vcpkg/clt.dmg
ssh vcpkg@HOSTMACHINE
chmod +x setup-guest.sh
./setup-guest.sh
rm setup-guest.sh
rm setup-box.sh
rm clt.dmg
exit

Shut down the VM cleanly.
Mint a SAS token to vcpkgimageminting/pvms with read, add, create, write, and list permissions.

Package the VM into a tarball. For example from a dev workstation:

ssh vcpkg@HOSTMACHINE
cd ~/Parallels
aa archive -d vcpkg-osx-<date>-arm64 -o vcpkg-osx-<date>-arm64.aar -enable-holes
brew install azcopy
azcopy copy vcpkg-osx-<date>-arm64.aar "https://vcpkgimageminting.blob.core.windows.net/pvms?<SAS>"
exit

Go to https://dev.azure.com/vcpkg/public/_settings/agentqueues and create a new self hosted Agent pool named PrOsx-YYYY-MM-DD-arm64 based on the current date. Grant microsoft.vcpkg.ci and microsoft.vcpkg.pr access.
Follow the "Deploying images" steps below for each machine in the fleet.

Deploying images

Running the VM

Run these steps on each machine to add to the fleet. Skip steps that were done implicitly above if this machine was used to build a box.

If this machine was used before, delete it from the pool of which it is a member from https://dev.azure.com/vcpkg/public/_settings/agentqueues
Log in to the machine using the KVM.
Check for software updates in macOS system settings

(Once only) install macosvm to ~ (this tarball is also backed up in our vcpkg-image-minting storage account). From a developer machine:

ssh vcpkg@HOSTMACHINE
curl -L -o macosvm-0.2-2-arm64-darwin21.tar.gz https://github.com/s-u/macosvm/releases/download/0.2-2/macosvm-0.2-2-arm64-darwin21.tar.gz
tar xvf macosvm-0.2-2-arm64-darwin21.tar.gz
rm macosvm-0.2-2-arm64-darwin21.tar.gz
exit

Skip if this is the image building machine. Mint a SAS token URI to the box to use from the Azure portal if you don't already have one, and download the VM. (Recommend running this via SSH from domain joined machine due to containing SAS tokens). From a developer machine:

ssh vcpkg@HOSTMACHINE
brew install azcopy
mkdir -p ~/Parallels
cd ~/Parallels
azcopy copy "https://vcpkgimageminting.blob.core.windows.net/pvms/vcpkg-osx-<DATE>-arm64.aar?<SAS>" vcpkg-osx-<DATE>-arm64.aar
aa extract -d vcpkg-osx-<DATE>-arm64 -i ./vcpkg-osx-<DATE>-arm64.aar -enable-holes
exit

Open a separate terminal window on the host and start the VM by running:
```
cd ~/Parallels/vcpkg-osx-<DATE>-arm64
~/macosvm ./vm.json
```
grab a PAT if you don't already have one

Copy the guest deploy script to the host, and run it with a first parameter of your PAT. From a developer machine:

scp register-guest.sh vcpkg@HOSTMACHINE:/Users/vcpkg/register-guest.sh
ssh vcpkg@HOSTMACHINE
rm .ssh/known_hosts
chmod +x register-guest.sh
./register-guest.sh PAT-GOES-HERE AGENT-NUMBER-GOES-HERE
rm register-guest.sh

That will cleanly shut down the VM. In the KVM's terminal, relaunch the VM in ephemeral mode with:
```
~/macosvm --ephemeral ./vm.json
```

Open a terminal window on the host and run the agent

ssh -i ~/Parallels/*/id_guest vcpkg@vcpkgs-Virtual-Machine.local
~/myagent/run.sh

Check that the machine shows up in the pool, and lock the vcpkg user on the host.
Lock the screen on the host.
Update the "vcpkg Macs" spreadsheet line for the machine with the new pool.

Getting an Azure Pipelines PAT

Personal Access Tokens are an important part of this process, and they are fairly easy to generate. On ADO, under the correct project (in vcpkg's case, "vcpkg"), click on the "User Settings" icon, then go to "Personal access tokens". It is the icon to the left of your user icon, in the top right corner.

Then, create a new token, give it a name, make sure it expires quickly, and give it a custom defined scope that includes the "Agent pools: Read & manage" permission (you'll need to "Show all scopes" to access this). You can now copy this token and use it to allow machines to join.

README.md

vcpkg-eg-mac VMs

Creating new base images

Prerequisites

Instructions (ARM64)

Deploying images

Running the VM

Getting an Azure Pipelines PAT

`vcpkg-eg-mac` VMs