On Wednesday 21 March 2007 14:46, Johannes Berg wrote:
> If the driver does not support radiotap, ieee80211_rx_monitor needs to
> expand the head for each packet. Currently, this is also true, but since
> currently no non-management frames are sent down the management
> interface, this is not an issue. If each data packet needs to be first
> reallocated though, it quickly becomes a problem for low-power embedded
> access points running hostapd.
>
That's why drivers should be modified to support radiotap.

> Additionally, the overhead of tacking on radiotap headers to each
> received frame is also rather high if you're only interested in
> receiving the information for management frames.
>
It's really not that much overhead.

-Michael Wu