Qubes Tools for Windows: advanced settings and troubleshooting

This document only applies to Qubes R3 (tools version 3.x) Only 64-bit Windows 7 (any edition) is supported currently. Windows 8+ support is under development. HVM templates are not supported yet. Specifically, user profiles are not yet moved to a VM's private image (fix incoming).

Installable components

Qubes Tools for Windows (QTW for short) contain several components than can be enabled or disabled during installation:

Shared components (required): common libraries used by QTW components.
Xen PV drivers: drivers for the virtual hardware exposed by Xen.
- Base Xen PV Drivers (required): paravirtual bus and interface drivers.
- Xen PV Disk Drivers: paravirtual storage drivers.
- Xen PV Network Drivers: paravirtual network drivers.
Qubes Core Agent: qrexec agent and services. Needed for proper integration with Qubes.
Qubes GUI Agent: video driver and gui agent that enable seamless showing of Windows applications on the secure Qubes desktop.

In testing VMs only it's probably a good idea to install a VNC server before installing QTW. If something goes very wrong with the Qubes gui agent, a VNC server should still allow access to the OS.

Verbose installation

If the install process fails you can retry it using the command line below to get a detailed installation log (and send that to us):

msiexec /i path-to-qubes-tools.msi /lv path-to-log-file.txt

Uninstalling QTW 3.x is not recommended. It will most likely make the OS non-bootable because drivers for Xen storage devices will be uninstalled. This will be fixed in the future.

Configuration

Starting from version 2.2.* various aspects of Qubes Tools for Windows can be configured through registry. Main configuration key is located in HKEY_LOCAL_MACHINE\SOFTWARE\Invisible Things Lab\Qubes Tools. Configuration values set on this level are global to all QTW components. It's possible to override global values with component-specific keys, this is useful mainly for setting log verbosity for troubleshooting. Possible configuration values are:

Name	Type	Description	Default value
LogDir	String	Directory where logs are created	c:\Program Files\Invisible Things Lab\Qubes Tools\log
LogLevel	DWORD	Log verbosity (see below)	2 (INFO)
LogRetention	DWORD	Maximum age of log files (in seconds), older logs are automatically deleted	604800 (7 days)

Possible log levels:

|| |0|Error|Serious errors that most likely cause irrecoverable failures| |1|Warning|Unexpected but non-fatal events| |2|Info|Useful information| |3|Debug|Internal state dumps for troubleshooting| |4|Verbose|Trace most function calls|

Debug and Verbose levels can generate large volume of logs and are intended for development/troubleshooting only.

To override global settings for a specific component, create a new key under the root key mentioned above and name it as the executable name, without .exe extension. For example, to change qrexec-agent's log level to Debug, set it like this:

Component-specific settings currently available:

Component	Setting	Type	Description	Default value
qga	UseDirtyBits	DWORD	Enable experimental feature of the gui agent/qvideo driver: use page table dirty bits to determine changed display regions. This can improve performance but may impact display responsiveness (some changes may not be detected resulting in "stale" image). Needs VM restart to apply change.	0
qga	DisableCursor	DWORD	Disable cursor in the VM. Useful for integration with Qubes desktop so you don't see two cursors. Can be disabled if you plan to use the VM through a remote desktop connection of some sort. Needs gui agent restart to apply change (locking OS/logoff should be enough since qga is restarted on desktop change).	1

Troubleshooting

If the VM is inaccessible (doesn't respond to qrexec commands, gui is not functioning), try to boot it in safe mode:

qvm-start --debug vmname
mash F8 on the boot screen to enable boot options and select Safe Mode (optionally with networking)

Safe Mode should at least give you access to logs (see above).

Please include appropriate logs when reporting bugs/problems. Starting from version 2.4.2 logs contain QTW version, but if you're using an earlier version be sure to mention which one. If the OS crashes (BSOD) please include the BSOD code and parameters in your bug report. The BSOD screen should be visible if you run the VM in debug mode (qvm-start --debug vmname). If it's not visible or the VM reboots automatically, try to start Windows in safe mode (see above) and 1) disable automatic restart on BSOD (Control Panel - System - Advanced system settings - Advanced - Startup and recovery), 2) check the system event log for BSOD events. If you can, send the memory.dmp dump file from c:\Windows. Xen logs (/var/log/xen/console/guest-*) are also useful as they contain pvdrivers diagnostic output.

If a specific component is malfunctioning, you can increase it's log verbosity as explained above to get more troubleshooting information. Below is a list of components:

|| |qrexec-agent|Responsible for most communication with Qubes (dom0 and other domains), secure clipboard, file copying, qrexec services.| |qrexec-client-vm|Used for communications by the qrexec protocol.| |qga|Gui agent.| |QgaWatchdog|Service that monitors session/desktop changes (logon/logoff/locking/UAC...) and simulates SAS sequence (ctrl-alt-del).| |qubesdb-daemon|Service for accessing Qubes configuration database.| |network-setup|Service that sets up network parameters according to VM's configuration.| |prepare-volume|Utility that initializes and formats the disk backed by private.img file. It's registered to run on next system boot during QTW setup, if that feature is selected (it can't run during the setup because Xen block device drivers are not yet active). It in turn registers move-profiles (see below) to run at early boot.| |move-profiles|Utility that moves user profiles directory to the private disk. It's registered as an early boot native executable (similar to chkdsk) so it can run before any profile files are opened by some other process. Its log is in a fixed location: c:\move-profiles.log (it can't use our common logger library so none of the log settings apply).|

Updates

When we publish new QTW version (which is announced on qubes-users Google Group) it's usually pushed to the current-testing or unstable repository first. To use versions from current-testing, run this in dom0:

qubes-dom0-update --enablerepo=qubes-dom0-current-testing qubes-windows-tools

That command will download a new QTW .iso from the testing repository. It goes without saying that you should backup your VMs before installing anything from testing repos.

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