schedule() or scheduler_tick() not called during qemu run

[Chan Kim]

Hello qemu experts,

I'm trying to debug a situation where the /init script is processed at the
end of the kernel_init function which is the final stage, but the last
command in the /init script which is 'exec /bin/sh' hangs after the first
call and return of schedule() function in my fpga test. The file system is
initramfs.cpio.gz and was made using busybox. If I replace the /init scritp
with a program which repeats printf("hello %d", cnt++), it stops after
117~118 times and I can see schedule() was called and finished before it
hangs.
So I tried to follow what's happening using qemu (though the virtual machine
is not exactly the same with the actual board), but when I set breakpoint in
schedule() or scheduler_tick(), the breakpoint never kicks in(Of course
other break points all work). Is this normal in qemu or is there something
wrong in my qemu execution(I mean in my virtual machine)?
BTW, this is an arm64 board.

Chan Kim