Examples of exceeding the supported CPU limits
If you exceed or fail to meet the supported CPU limits on a Linux or Windows guest OS, you may encounter the following issues.
Example 1: Exceeding the maximum vCPU limit on a Linux guest OS
For an x86-32 Debian 10 OS, if you set the Maximum number of vCPUs field to 40, the Topology field is set to 10 sockets with 4 cores per socket. This exceeds the 32 CPU limit and although the 32 vCPUs are listed, any excess CPUs are not displayed. Similarly, the number of cores per socket is displayed in the same way, however, the number of sockets is limited to only the supported numbers to ensure that the total vCPUs do not exceed 32.
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
Address sizes: 48 bits physical, 48 bits virtual
On-line CPU(s) list: 0-31
Thread(s) per core: 1
Core(s) per socket: 4
Example 2: Exceeding the socket limit on a Windows guest OS
For an x86-64 Windows 10 OS, if you set the Maximum number of vCPUs field to 10, the Topology field is set to 5 sockets with 2 cores per socket. This exceeds the Windows license limit of 4 sockets for Enterprise SKUs. In your Windows guest, you will see only 4 sockets. Hence the total vCPUs number shown is 8.
Example 3: Failing to meet the minimum vCPU requirement on a Windows guest OS
For an x86-64 Windows 10 OS, if you set the Maximum number of vCPUs field to 1, the Topology field is set to 1 socket with 1 core per socket. This does not meet the minimum vCPU requirement of 2 CPUs and so XenCenter displays a warning to prompt you to select at least 2 vCPUs for your Windows guest.