**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.
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.
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:
|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:
|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|
**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:
|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).|
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:
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.
