11 Troubleshooting

11.3.2 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 3.7.1.2,“Advanced” tab, page 46).

11.3.3 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 3.7.2,System settings, page 47), or upgrade the guest to a newer
kernel.2
11.4 Windows hosts

11.4.1 VBoxSVC out-of-process COM server issues

VirtualBoxmakes use of the Microsoft Component Object Model (COM) for inter- and
intra-processcommunication. Thisallows VirtualBox to share a common configuration
among different virtual machine processes and provide several user interface options
based on a common 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, it requests access to the COM server and
Windows automatically starts the process. Note that it should never be started by the
end user.
When the last process disconnects from the COM server,it will terminate itself after
some seconds. The VirtualBox configuration (XML files) is maintained and owned by
the COM server and the files are locked whenever the server runs.
In some cases - such as when a virtual machine is terminated unexpectedly - the
COM server will not notice that the client is disconnected and stay active for a longer
period (10 minutes or so) keeping the configuration files locked. In other rare cases
2See http://www.mail-archive.com/git-commits-head@vger.kernel.org/msg30813.
htmlfor details about the kernel fix.
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