To update the time in a LineageOS 23.0 virtual machine running under Virtual Machine Manager (virt-manager) on Debian 13 GNOME after restoring a snapshot, follow these steps:

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1. Ensure Time Synchronization is Enabled in the VM

LineageOS (Android) does not natively support NTP (Network Time Protocol) in the same way as a traditional Linux system. However, you can ensure time sync is enabled:

• Check if NTP is enabled: On the LineageOS VM, go to Settings > System > Date & time and ensure "Use network-provided time" is enabled.

• If not syncing automatically:

  • Open a terminal in the VM (if available) or use ADB:

    bash
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    adb shell
    su
    date -s YYYYMMDD.HHMMSS

    Replace YYYYMMDD.HHMMSS with the current time.

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2. Configure QEMU/KVM Time Synchronization

Virtual Machine Manager uses QEMU/KVM, which can pass the host's time to the guest. Ensure the VM is configured to use the host's time:

• Edit the VM's XML configuration:

  1. Shut down the VM.
  2. Open a terminal on the host (Debian 13) and run:

     bash
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     virsh edit <vm-name>

  3. Locate the <clock> section and ensure it includes:

     xml
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     <clock offset="utc">
       <timer name="hypervclock" present="yes"/>
       <timer name="hpet" present="no"/>
     </clock>

  4. Save and exit. The VM will now sync its clock with the host.

• Alternative: Add a host time source by adding:

  xml
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  <clock offset="utc">
    <timer name="hypervclock" present="yes"/>
    <timer name="kvm-clock" present="yes"/>
  </clock>

• Restart the VM for changes to take effect.

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3. Force Time Sync via QEMU Guest Agent (if available)

If your LineageOS VM has the QEMU Guest Agent installed (unlikely by default for Android, but possible with custom kernels):

1. Ensure the agent is running in the VM.
2. On the host, check if the agent is connected:

   bash
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   virsh qemu-agent-command <vm-name> '{"execute":"guest-ping"}'

3. If available, force a time sync:

   bash
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   virsh qemu-agent-command <vm-name> '{"execute":"guest-set-time", "arguments": {"time": "<current-utc-time>"}}'

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4. Manual Time Sync via ADB

If the above methods fail, manually set the time via ADB:

1. Connect to the VM:

   bash
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   adb connect <vm-ip>:5555

2. Open a shell:

   bash
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   adb shell
   su

3. Set the time manually:

   bash
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   date -s YYYYMMDD.HHMMSS

   Example:

   bash
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   date -s 20260713.143000

4. Verify:

   bash
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   date

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5. Check Host Timezone

Ensure your Debian 13 host has the correct timezone:

bash
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timedatectl

If not, set it:

bash
Copy
sudo timedatectl set-timezone Europe/Paris

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6. Restart the VM

After making changes, restart the VM to ensure all settings take effect.

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Why This Happens

• Restoring a snapshot reverts the VM's state, including its internal clock.
• Android (LineageOS) does not always sync time automatically in a virtualized environment.
• QEMU/KVM may not pass the host's time correctly without explicit configuration.

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Next Steps If the time still drifts, consider installing a custom kernel in LineageOS with better timekeeping support or using a time sync app from the Play Store.