How to disable cpu cores in Linux 3.4 kernel?

Question

I have a question about how to disable cpu cores in my linux-3.4 version. I typed "echo 0 > /sys/devices/system/cpu/cpu0/online" on the shell to only activate cpu1 except for cpu0 (because there are dual cores in my cortex-A20 board) but there are no existing directory in my linux...

So I went to the directory in my linux such as capture posted:

and don't know how to disable cpu cores..

are there any way to disable cpu0 before building kernel image or running

linux 3-4 after porting kernel image to sdcard?

Answer 1

You can not disable cpu0, only the above example cpu1,2, 3.. etc