Function cpu_num 

pub fn cpu_num() -> usize

Gets the number of CPUs running in the system.

When SMP is disabled, this function always returns 1.

When SMP is enabled, it’s the smaller one between the platform-declared CPU number ax_plat::power::cpu_num and the configured maximum CPU number ax_config::plat::MAX_CPU_NUM.

This value is determined during the BSP initialization phase.