12 Troubleshooting 12.1.2 Collecting debugging information For problem determination, it is often important to collect debugging information which can be analyzed by VirtualBox support. This section contains information about what kind of informa- tion can be obtained. Every time VirtualBox starts up a VM, a so-called “release log file” is created containing lots of information about the VM configuration and runtime events. The log file is called VBox.log and resides in the VM log file folder. Typically this will be a directory like this: $HOME/VirtualBox VMs/{machinename}/Logs When starting a VM, the configuration file of the last run will be renamed to .1, up to .3. Sometimes when there is a problem, it is useful to have a look at the logs. Also when requesting support for VirtualBox, supplying the corresponding log file is mandatory. For convenience, for each virtual machine, the VirtualBox main window can show these logs in a window. To access it, select a virtual machine from the list on the left and select “Show logs...“ from the “Machine” window. The release log file (VBox.log) contains a wealth of diagnostic information, such as Host OS type and version, VirtualBox version and build (32-bit or 64-bit), a complete dump of the guest’s configuration (CFGM), detailed information about the host CPU type and supported features, whether hardware virtualization is enabled, information about VT-x/AMD-V setup, state tran- sitions (creating, running, paused, stopping, etc.), guest BIOS messages, Guest Additions mes- sages, device-specific log entries and, at the end of execution, final guest state and condensed statistics. In case of crashes, it is very important to collect crash dumps. This is true for both host and guest crashes. For information about enabling core dumps on Linux, Solaris, and OS X systems, refer to the core dump article on the VirtualBox website.1 You can also use VBoxManage debugvm to create a dump of a complete virtual machine see chapter 8.30, VBoxManage debugvm, page 129. For network related problems, it is often helpful to capture a trace of network traffic. If the traffic is routed through an adapter on the host, it is possible to use Wireshark or a similar tool to capture the traffic there. However, this often also includes a lot of traffic unrelated to the VM. VirtualBox provides an ability to capture network traffic only on a specific VM’s network adapter. Refer to the network tracing article on the VirtualBox website2 for information on enabling this capture. The trace files created by VirtualBox are in .pcap format and can be easily analyzed with Wireshark. 12.1.3 The built-in VM debugger VirtualBox includes a built-in VM debugger, which advanced users may find useful. This debug- ger allows for examining and, to some extent, controlling the VM state. Warning: Use the VM debugger at your own risk. There is no support for it, and the following documentation is only made available for advanced users with a very high level of familiarity with the x86/AMD64 machine instruction set, as well as detailed knowledge of the PC architecture. A degree of familiarity with the internals of the guest OS in question may also be very helpful. The VM debugger is available in all regular production versions of VirtualBox, but it is disabled by default because the average user will have little use for it. There are two ways to access the debugger: 1http://www.virtualbox.org/wiki/Core_dump. 2http://www.virtualbox.org/wiki/Network_tips. 165