packets seen in ifconfig but not on tcpdump

On ifconfig I can see the number of packets sent/received with the tx/rx values. With that interface on promiscuous mode, if I turn on tcpdump on that interface I should see all packets sent/received on that interface right? Using: tcpdump -XX -e -n -s0 -i (There may be redundancy in the options :p) And yet I don't see all packets sent. Any ideas? **EDIT**: also, I read the ifconfig manual and it reads: _"Ifconfig is used to configure the kernel-resident network interfaces."_ So, ifconfig reads tx/rx at kernel level right? Is there any way to get these readings at driver level? **EDIT2:** also, can the driver be programmed to send the packets to the kernel AND to a running program? **EDIT3:** could I make a program to sniff _ANY_ bytes passing on the interface, regardless of their format? Perhaps tcpdump is not giving me the packets because it cannot perceive their format.