4 Guest Additions 4.3.2 Automatic mounting Starting with version 4.0, VirtualBox can mount shared folders automatically, at your option. If automatic mounting is enabled for a specific shared folder, the Guest Additions will automatically mount that folder as soon as a user logs into the guest OS. The details depend on the guest OS type: • With Windows guests, any auto-mounted shared folder will receive its own drive letter (e.g. E:) depending on the free drive letters remaining in the guest. If there no free drive letters left, auto-mounting will fail as a result, the number of auto- mounted shared folders is typically limited to 22 or less with Windows guests. • With Linux guests, auto-mounted shared folders are mounted into the /media directory, along with the prefix sf_. For example, the shared folder myfiles would be mounted to /media/sf_myfiles on Linux and /mnt/sf_myfiles on Solaris. The guest property /VirtualBox/GuestAdd/SharedFolders/MountPrefix determines the prefix that is used. Change that guest property to a value other than “sf” to change that prefix see chapter 4.6, Guest properties, page 66 for details. Note: Access to auto-mounted shared folders is only granted to the user group vboxsf, which is created by the VirtualBox Guest Additions installer. Hence guest users have to be member of that group to have read/write access or to have read-only access in case the folder is not mapped writable. To change the mount directory to something other than /media, you can set the guest property /VirtualBox/GuestAdd/SharedFolders/MountDir. • Solaris guests behave like Linux guests except that /mnt is used as the default mount directory instead of /media. To have any changes to auto-mounted shared folders applied while a VM is running, the guest OS needs to be rebooted. (This applies only to auto-mounted shared folders, not the ones which are mounted manually.) 4.4 Hardware-accelerated graphics 4.4.1 Hardware 3D acceleration (OpenGL and Direct3D 8/9) The VirtualBox Guest Additions contain experimental hardware 3D support for Windows, Linux and Solaris guests.1 With this feature, if an application inside your virtual machine uses 3D features through the OpenGL or Direct3D 8/9 programming interfaces, instead of emulating them in software (which would be slow), VirtualBox will attempt to use your host’s 3D hardware. This works for all supported host platforms (Windows, Mac, Linux, Solaris), provided that your host operating system can make use of your accelerated 3D hardware in the first place. The 3D acceleration currently has the following preconditions: 1. It is only available for certain Windows, Linux and Solaris guests. In particular: 1OpenGL support for Windows guests was added with VirtualBox 2.1 support for Linux and Solaris followed with VirtualBox 2.2. With VirtualBox 3.0, Direct3D 8/9 support was added for Windows guests. OpenGL 2.0 is now supported as well. 64