12 Troubleshooting 12.4.2 AMD Barcelona CPUs Most Linux-based guests will fail with AMD Phenoms or Barcelona-level Opterons due to a bug in the Linux kernel. Enable the I/O-APIC to work around the problem (see chapter 3.4, System settings, page 43). 12.4.3 Buggy Linux 2.6 kernel versions The following bugs in Linux kernels prevent them from executing correctly in VirtualBox, causing VM boot crashes: • The Linux kernel version 2.6.18 (and some 2.6.17 versions) introduced a race condition that can cause boot crashes in VirtualBox. Please use a kernel version 2.6.19 or later. • With hardware virtualization and the I/O APIC enabled, kernels before 2.6.24-rc6 may panic on boot with the following message: Kernel panic - not syncing: IO-APIC + timer doesn’t work! Boot with apic=debug and send a report. Then try booting with the ’noapic’ option If you see this message, either disable hardware virtualization or the I/O APIC (see chapter 3.4, System settings, page 43), or upgrade the guest to a newer kernel.4 12.4.4 Shared clipboard, auto-resizing and seamless desktop in X11 guests Guest desktop services in guests running the X11 window system (Solaris, Linux and others) are provided by a guest service called VBoxClient, which runs under the ID of the user who started the desktop session and is automatically started using the following command lines VBoxClient --clipboard VBoxClient --display VBoxClient --seamless when your X11 user session is started if you are using a common desktop environment (Gnome, KDE and others). If a particular desktop service is not working correctly, it is worth checking whether the process which should provide it is running. The VBoxClient processes create files in the user’s home directory with names of the form .vboxclient-*.pid when they are running in order to prevent a given service from being started twice. It can happen due to misconfiguration that these files are created owned by root and not deleted when the services are stopped, which will prevent them from being started in future sessions. If the services cannot be started, you may wish to check whether these files still exist. 12.5 Windows hosts 12.5.1 VBoxSVC out-of-process COM server issues VirtualBox makes use of the Microsoft Component Object Model (COM) for inter- and intra- process communication. This allows VirtualBox to share a common configuration among dif- ferent virtual machine processes and provide several user interface options based on a com- mon architecture. All global status information and configuration is maintained by the process VBoxSVC.exe, which is an out-of-process COM server. Whenever a VirtualBox process is started, 4See http://www.mail-archive.com/git-commits-head@vger.kernel.org/msg30813.html for details about the kernel fix. 172