the booting of seconday cpu is initiated by the primary core. and some work is completed on the primary cpu and some is completed on the secondary cpu to complete the hotplug operation for cpu_up.
I am trying to find the exact instruction that is executed on the primary cpu, that triggers the secondary cpu to start, and further it will check the pen_release varaible's value.
Can you please explain the procedure of starting the secondary cpu, and the uses of pen_release global with respect to Linux kernel with SMP enabled.