dev_info, dev_dbg, dev_err: how to see them?

[marcolazzaroni]

I see in the kernel code some calls to functions in the object.
I change one call from dev_info to dev_err and now I can see it in dmesg.
I suppost there's a better way to see dev_info (or dev_debg): how do I get them?
Cheers
  Marco