VM BIOS (virtual machine basic input/output system)
What is a VM BIOS (virtual machine basic input/output system)?
A VM BIOS (virtual machine basic input/output system) is the set of instructions that controls the booting process of a VM.
Because a VM is an emulation of a physical computer, most VMs require a BIOS to control booting and input/output operations. A VM BIOS is similar to a BIOS on a physical computer or server, but its functionality is often more limited. In fact, in most cases, the only setting accessible from a VM BIOS is the boot order. This is useful if an administrator wants to boot a VM image from a DVD, USB drive or other media, for example.
Many of the BIOS settings traditionally available on physical machines are passed from the host machine to the VMs. For example, VMs inherit date and time settings from their physical host via virtualization utilities such as Microsoft Hyper-V Integration Services and VMware Tools.
Accessing and changing VM BIOS settings
Each hypervisor has a different process for accessing and editing the VM BIOS. In Hyper-V, administrators can access VM BIOS settings through Hyper-V Manager. Similarly, in VMware environments, admins can adjust VM BIOS settings through vSphere.
Available VM BIOS settings vary by VM version and format. For example, in addition to adjusting boot order, BIOS settings for Hyper-V generation 2 VMs offer a secure boot option, a feature that prevents unauthorized code from running on boot up.
