Changing MAC address on the Fly on old kernel 2.6.x

Question

I'm doing some research on old kernels and running the following on 2.6.7 or 2.6.8 gives a resource busy error. But on 2.6.28 the command works as expected. How would I determine which kernel allowed this command to change the mac address on the fly? ip link set dev addr

You can see some screenshots below. Thank you!
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Answer 1

This turned out to be a driver related issue. Once we received new drivers from the manufacture the task worked as its supposed to be.