= How to create a core dump on Linux =

A core dump is very helpful for helping us tracking down crashes of !VirtualBox. To create a core dump, start !VirtualBox from a command line (e.g. xterm):
{{{
$ ulimit -c unlimited
$ sudo su
# echo -n 1 > /proc/sys/kernel/core_uses_pid
# echo -n 1 > /proc/sys/fs/suid_dumpable
# exit
$ VirtualBox
}}}
or better start the VM directly:
{{{
$ ulimit -c unlimited
$ sudo su
# echo -n 1 > /proc/sys/kernel/core_uses_pid
# echo -n 1 > /proc/sys/fs/suid_dumpable
# exit
$ /usr/lib/virtualbox/VirtualBox -startvm VM_NAME
}}}
Ensure that '''no''' startup script (`~/.bashrc`, `~/.bash_profile`, `~/.profile`) contains an instruction like `ulimit -c 0` as the limit cannot be increased once it was set to zero.

Starting with version 2.0.0, the !VirtualBox processes are started `suid root`, that is, with permissions to do things that "normal" applications cannot. This is the reason for the
{{{
$ sudo su
$ echo -n 1 > /proc/sys/fs/suid_dumpable
$ exit
}}}
before starting the VM/GUI (note that `sudo echo` will not do what we want here).

When !VirtualBox or one of its processes crashes, a file core.<pid> is created in the current directory. Be aware that core dumps can be very huge. Please compress the file before submitting it to a bug report. Or better don't attach the file to a report. Note that this core dump can contain a memory dump of your guest which can include sensitive information. Send it to frank _dot_ mehnert _at_ oracle _dot_ com if the compressed file is smaller than 5MB. Contact me directly otherwise.

If several core files are created, you can check which process created them using the command
{{{
$ file core.<pid>
}}}
to be sure of the right one to send.

= How to create dumps on Mac OS X =
To create a core dump on Mac OS X, start !VirtualBox from a command line:
{{{
$ ulimit -c unlimited
$ VirtualBox
}}}
or better start the VM directly:
{{{
$ ulimit -c unlimited
$ /Applications/VirtualBox.app/Contents/MacOS/VirtualBox -startvm VM_NAME
}}}
Ensure that '''no''' startup script (`~/.bashrc`, `~/.bash_profile`, `~/.profile`) contains an instruction like `ulimit -c 0` as the limit cannot be increased once it was set to zero.

The core files can be found in the /cores folder.

= How to create dumps on !OpenSolaris =
To get core on !OpenSolaris host run the following command as root
{{{
# coreadm -g /var/cores/core.%f.%p -i core.%f.%p -e global -e process -e global-setid -e proc-setid -e log
}}}

The cores will now be placed in /var/cores/ folder with the global dumps will go into /var/crash/<hostname>

= Forcing !VirtualBox to terminate with a core dump =
Sometimes it is required to force a !VirtualBox process to terminate, for example, a VM hangs for some unknown reason. On Linux, this can be done as follows:
{{{
$ ulimit -c unlimited
$ sudo echo -n 1 > /proc/sys/fs/suid_dumpable
$ /usr/lib/virtualbox/VirtualBox -startvm VM_NAME &
$ pidof VirtualBox
7145
$ kill -4 7145
}}}
As an alternative to ''kill'' you can do
{{{
$ pidof VirtualBox
7145
$ gcore 7145
}}}
On Mac OS X:
{{{
$ ulimit -c unlimited
$ /Applications/VirtualBox.app/Contents/MacOS/VirtualBox -startvm VM_NAME &
$ ps aux|grep VirtualBox
... 7145 ... VirtualBox ...
$ kill -4 7145
}}}

On Solaris:
{{{
# ulimit -c unlimited
# /opt/VirtualBox/amd64/bin/VirtualBox -startvm VM_NAME &
# ps -ef|grep VirtualBox
... 7145 ... VirtualBox ...
# kill -4 7145
}}}

You can find result core file according location specified in coreadm 
{{{
# coreadm
}}}

Passing the signal number 4 (`SIGILL`) is essential! The same applies to the alternative frontends `VBoxHeadless` and `VBoxSDL`.


  
= Minidumps on Windows =
Please visit this [http://support.microsoft.com/kb/315263 Microsoft site] for more details about minidumps[[BR]]
Please visit the [http://blogs.technet.com/askperf/archive/2007/06/15/capturing-application-crash-dumps.aspx Microsoft Performance Team blog] for more details about Application crash dumps