A: For supported Linux virtual machines (VMs) with version 3.4 or later kernel, the Linux VMs are supported to the full 64 virtual processors possible with Windows Server 2012 Hyper-V. For Linux distributions that are not 3.4 or later, then the Linux integration services need to be installed, and up to eight vCPUs are supported.

The latest Integration Services available at this time are version 3.3 from the Microsoft website