disable_irq in ndo_poll_controller

Hi list,

I found that there are three disable irq method in nicard drivers
ndo_poll_controller implementation :
1.disable_irq
2.loacle_irq_save
3.program nicard's register

why need disable irq in ndo_poll_controller?
Is all the three method equivalent?
Now I'm adding netconsole support to nic of our soc, which can I take
from the tree method?

Thanks in advance,
Jisheng