vphone
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      • Pairing a virtual Apple Watch with a virtual iPhone

      A watchOS 26.4 (Watch7,18) guest pairs with an iOS 26 guest through the phone's Watch app, and the initial sync completes. No Bluetooth hardware is involved: Apple's VM builds carry the plumbing.

      Checked on 2026-10-20: a watchos watch and a minimal iPhone17,3 of iOS 26.4 (23E246), both on cloudOS 26.4 (23E244) and on the NAT network with peers reachable, paired from the phone's Watch app. A minimal phone comes up in Setup Assistant (it has no template); skip it (setup.skip) or go through it before opening the Watch app.

      How pairing works between VMs

      • Discovery and link: NetworkRelay over IP. On a VM, nanoregistryd pairs through NetworkRelay (networkrelay_pairing || IsVirtualDevice), and terminusd runs only NRLinkManagerWired. The watch advertises Bonjour _nrd._tcp, the phone browses for it, and the PIN pairing runs over IKEv2.
      • Virtual Bluetooth. On a VM, bluetoothd drives a built-in virtual LE controller (BTVC) whose radio is Bonjour _btvc._tcp. It needs the device tree node arm-io/bluetooth with transport-encoding = 10, which vphone600's tree has (and the research board conversion adds), and kern.hv_vmm_present. The feature flag BluetoothFeatures/EnableBTVCLeConnection gates its LE connections and is off as shipped.
      • Version gate. NRPairingCompatibilityVersionInfo: watchOS 26.4 is version 26; iOS 26.4 accepts 25 to 26, iOS 18.1 at most 23. The phone has to run iOS 26.

      What the VMs need

      RequirementPatchWhy
      The machines reach each othervm config --nat-peers (on by default)vmnet isolates guests on the shared NAT network from each other; _nrd._tcp and _btvc._tcp are guest-to-guest
      /product/watch-companion = 1 on the phonedevicetree-cfw-watch_companionvphone600's is syscfg/waco, which the VM's syscfg lacks, so iBoot drops it. MobileGestalt then says the phone pairs with no watch: +[NRRegistry _supportsWatch] is NO, the Watch app has no icon, and NanoRegistry's clients load the registry once and never see the watch nanoregistryd discovers ("Searching for Apple Watch" times out)
      EnableBTVCLeConnection on bothsystem-bluetoothd-cfw-btvc_le_connection (cfw install), filesystem-exp-btvc_le_connection (restore image)LE connections over the virtual controller
      Activation on the watchfilesystem-boot-mobileactivationd_should_hactivate in watchosAfter the PIN, the Watch app asks the watch for an activation request; an unactivated VM watch cannot make one ("Activation Failed! (Decoded request from Gizmo is nil)")

      The flag needs a reboot to change at runtime: feature flags are cached in shared memory (com.apple.featureflags.shm), so restarting bluetoothd is not enough. A runtime override goes in /var/preferences/FeatureFlags/Domain/BluetoothFeatures.plist.

      Pairing

      1. Create the watch (vm create --device Watch7,18, preset watchos) and an iOS 26 phone, and start both.
      2. On the phone, open the Watch app (com.apple.Bridge): Start Pairing → Set Up for Myself. The phone lists the watch as "Apple Watch NNNNN"; choose it.
      3. The watch shows a six-digit code. Type it in the phone's window: the VM has a hardware keyboard, so there is no on-screen keypad.
      4. Continue on the phone. "Apple Watch is Syncing" takes about 8 minutes: three pairedsyncd activities (appconduitd 300 s, appconduitd.appstate 60 s, tccd 60 s) get no answer from the watch and end by timeout. The sync then reaches 100 %.

      Pitfalls

      • A phone built from a template with the trimmed service profile (the standard default) has the pairing daemons off: terminusd (NetworkRelay), identityservicesd, nanobackupd, nanoprefsyncd, nanotimekitcompaniond, security.otpaird, watchpresenced, magicswitchd.companion. Build the phone with minimal, or keep those labels (allow) when applying the profile.
      • If the phone remembers an unfinished pairing, choose Start Over.
      • Killing only the watch's Setup leaves stale pairing managers in terminusd, and the phone can connect to one whose code no screen shows. Restart terminusd, nanoregistryd and Setup together.
      • A tap on a dimmed watch display only wakes it; press the crown (Home) first.
      • The watch's Setup crashed in a UIKit layout trap ("Screen class invalid") on the language list before the watch display patches; pairing from the phone avoids that screen.