Help needed in understanding hostapd design

Krishna Chaitanya chaitanya.mgit
Wed May 28 02:05:22 PDT 2014

On Wed, May 28, 2014 at 9:26 AM, Balaramulu Paduchuri
<p.balaramulu at> wrote:
> Hostapd experts, please help
> Thanks
> On Mon, May 26, 2014 at 6:55 PM, Balaramulu Paduchuri <p.balaramulu at> wrote:
>> Hi all,
>> I am trying to understand hostapd source code since some days and i struck with following questions in my mind. I checked the developer documentation before coming here. Also i don't have driver experience before.
>> I learnt that, driver specific functionality will be written in driver_xxx.c in src/drivers directory. But what is the difference between driver_nl80211.c( This is for configuring wireless adapter using netlink) and driver_hostap.c Do we have to use both for a wireless adapter ? Suppose if device supports cfg80211, then also do we need driver_hostap.c

driver_xxx files define how the hostapd/wpa_supplicant communications
with its kernel counterpart (cfg80211/other FMAC drivers without
cfg80211). Depending on the type of device driver we choose the
interface, mostly all device drivers use cfg80211 which supprts
wext/nl80211 remaingin drivers are old and not used mostly.

>> How driver_nl802.11.c functions will be triggered ?

wpa_supplicant/hostapd calls this functions usign the drv_xxx calls.

>> How the config information from hostapd.conf will be passed to wireless driver stack ?

Again depends on the driver_xxx, in case of driver_nl80211 it will be
using Netlink Messages.

I think the developer documentation is good, please read it in detail.

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