Resumen de resultados y comparación con meta-análisis previos

The following general settings are available throughVBoxManage modifyvm:

• --name <name>: This changes the VM’s name and possibly renames the internal virtual machine files, as described withVBoxManage createvmabove.

• --groups <group>, ...: This changes the group membership of a VM. Groups always start with a/and can be nested. By default VMs are in group/.

• --description <desc>: This changes the VM’s description, which is a way to record details about the VM in a way which is meaningful for the user. The GUI interprets HTML formatting, the command line allows arbitrary strings potentially containing multiple lines. • --ostype <ostype>: This specifies what guest operating system is supposed to run in the VM. To learn about the various identifiers that can be used here, use VBoxManage list ostypes.

• --memory <memorysize>: This sets the amount of RAM, in MB, that the virtual machine should allocate for itself from the host. See the remarks in chapter1.7,Creating your first virtual machine, page18for more information.

• --vram <vramsize>: This sets the amount of RAM that the virtual graphics card should have. See chapter3.5,Display settings, page51for details.

• --acpi on|off;--ioapic on|off: These two determine whether the VM should have ACPI and I/O APIC support, respectively; see chapter3.4.1,“Motherboard” tab, page48for details.

• --hardwareuuid <uuid>: The UUID presented to the guest via memory tables (DMI/SMBIOS), hardware and guest properties. By default this is the same as the VM uuid. Useful when cloning a VM. Teleporting takes care of this automatically.

• --cpus <cpucount>: This sets the number of virtual CPUs for the virtual machine (see chapter3.4.2, “Processor” tab, page50). If CPU hot-plugging is enabled (see below), this then sets the maximum number of virtual CPUs that can be plugged into the virtual ma- chines.

• --cpuhotplug on|off: This enables CPU hot-plugging. When enabled, virtual CPUs can be added to and removed from a virtual machine while it is running. See chapter9.5,CPU hot-plugging, page180for more information.

• --plugcpu|unplugcpu <id>: If CPU hot-plugging is enabled (see above), this adds a virtual CPU to the virtual machines (or removes one). <id> specifies the index of the virtual CPU to be added or removed and must be a number from 0 to the maximum no. of CPUs configured with the--cpusoption. CPU 0 can never be removed.

• --cpuexecutioncap <1-100>: This setting controls how much cpu time a virtual CPU can use. A value of 50 implies a single virtual CPU can use up to 50% of a single host CPU. • --pae on|off: This enables/disables PAE (see chapter3.4.2,“Processor” tab, page50). • --longmode on|off: This enables/disables long mode (see chapter3.4.2,“Processor” tab,

page50).

• --synthcpu on|off: This setting determines whether VirtualBox will expose a synthetic CPU to the guest to allow live migration between host systems that differ significantly. • --hpet on|off: This enables/disables a High Precision Event Timer (HPET) which can

replace the legacy system timers. This is turned off by default. Note that Windows supports a HPET only from Vista onwards.

• --hwvirtex on|off: This enables or disables the use of hardware virtualization exten- sions (Intel VT-x or AMD-V) in the processor of your host system; see chapter10.3,Hard- ware vs. software virtualization, page220.

• --triplefaultreset on|off: This setting allows to reset the guest instead of triggering a Guru Meditation. Some guests raise a triple fault to reset the CPU so sometimes this is desired behavior. Works only for non-SMP guests.

• --paravirtprovider none|default|legacy|minimal|hyperv|kvm: This setting speci- fies which paravirtualization interface to provide to the guest operating system. Specifying

none explicitly turns off exposing any paravirtualization interface. The option default, will pick an appropriate interface depending on the guest OS type while starting the VM. This is the default option chosen while creating new VMs. Thelegacyoption is chosen for VMs which were created with older VirtualBox versions and will pick a paravirtualization interface while starting the VM with VirtualBox 5.0 and newer. The minimalprovider is mandatory for Mac OS X guests, while kvmandhypervare recommended for Linux and Windows guests respectively. These options are explained in detail under chapter 10.4,

Paravirtualization providers, page221.

• --nestedpaging on|off: If hardware virtualization is enabled, this additional setting enables or disables the use of the nested paging feature in the processor of your host system; see chapter10.3,Hardware vs. software virtualization, page220.

• --largepages on|off: If hardware virtualization and nested paging are enabled, for Intel VT-x only, an additional performance improvement of up to 5% can be obtained by enabling this setting. This causes the hypervisor to use large pages to reduce TLB use and overhead.

• --vtxvpid on|off: If hardware virtualization is enabled, for Intel VT-x only, this addi- tional setting enables or disables the use of the tagged TLB (VPID) feature in the processor of your host system; see chapter10.3,Hardware vs. software virtualization, page220. • --vtxux on|off: If hardware virtualization is enabled, for Intel VT-x only, this setting

enables or disables the use of the unrestricted guest mode feature for executing your guest. • --accelerate3d on|off: This enables, if the Guest Additions are installed, whether hard- ware 3D acceleration should be available; see chapter 4.5.1, Hardware 3D acceleration (OpenGL and Direct3D 8/9), page74.

• --accelerate2dvideo on|off: This enables, if the Guest Additions are installed, whether 2D video acceleration should be available; see chapter4.5.2,Hardware 2D video acceleration for Windows guests, page76.

• --chipset piix3|ich9: By default VirtualBox emulates an Intel PIIX3 chipset. Usually there is no reason to change the default setting unless it is required to relax some of its constraints; see chapter3.4.1,“Motherboard” tab, page48.

• You can influence the BIOS logo that is displayed when a virtual machine starts up with a number of settings. Per default, a VirtualBox logo is displayed.

With --bioslogofadein on|off and--bioslogofadeout on|off, you can determine whether the logo should fade in and out, respectively.

With--bioslogodisplaytime <msec>you can set how long the logo should be visible, in milliseconds.

With --bioslogoimagepath <imagepath> you can, if you are so inclined, replace the image that is shown, with your own logo. The image must be an uncompressed 256 color BMP file without color space information (Windows 3.0 format). The image must not be bigger than 640 x 480.

• --biosbootmenu disabled|menuonly|messageandmenu: This specifies whether the BIOS allows the user to select a temporary boot device. menuonlysuppresses the message, but the user can still press F12 to select a temporary boot device.

• --nicbootprio<1-N> <priority>: This specifies the order in which NICs are tried for booting over the network (using PXE). The priority is an integer in the 0 to 4 range. Priority 1 is the highest, priority 4 is low. Priority 0, which is the default unless otherwise specified, is the lowest.

Note that this option only has effect when the Intel PXE boot ROM is used.

• --biospxedebug on|off: This option enables additional debugging output when using the Intel PXE boot ROM. The output will be written to the release log file (chapter12.1.2,

Collecting debugging information, page228.

• --boot<1-4> none|floppy|dvd|disk|net: This specifies the boot order for the virtual machine. There are four “slots”, which the VM will try to access from 1 to 4, and for each of which you can set a device that the VM should attempt to boot from.

• --rtcuseutc on|off: This option lets the real-time clock (RTC) operate in UTC time (see chapter3.4.1,“Motherboard” tab, page48).

• --biossystemtimeoffset <ms>: This allows you to set a fixed time offset of the guest relative to the host time. The offset is specified in milliseconds. If the offset is positive the guest time runs ahead the host time.

• --snapshotfolder default|<path>: This allows you to specify the folder in which snap- shots will be kept for a virtual machine.

• --firmware efi|bios: Specifies which firmware is used to boot particular virtual ma- chine: EFI or BIOS. Use EFI only if your fully understand what you’re doing.

• --guestmemoryballoon <size>sets the default size of the guest memory balloon, that is, memory allocated by the VirtualBox Guest Additions from the guest operating system and returned to the hypervisor for re-use by other virtual machines. <size>must be specified in megabytes. The default size is 0 megabytes. For details, see chapter 4.9.1, Memory ballooning, page79.

• --defaultfrontend default|<name>: This allows you to specify the default frontend which will be used when starting this VM; see chapter 8.12, VBoxManage startvm, page

141for details.