What does Armv8.x-A mean?
There are different versions of the Arm architecture. These different versions are usually shown as ArmvX, in which X is the version number. For example, Armv8-A means version 8 of the Arm A-profile architecture. A version such as Armv8-A is a major release of the architecture.
However, there are also minor versions that are added to a major release. These minor version are called .x extensions. For example, Armv8.1-A means version 8 of the A-profile architecture, extended by the .1 extension.