cfg80211: questions regarding cfg80211_ibss_joined()

cfg80211: questions regarding cfg80211_ibss_joined()

[Holger Schurig]

Hi !

I'm currently adding IBSS to libertas+cfg80211. Now I'd like
to get some clarifications:

a) when I create a new IBSS and i get a successful response to
   the CMD_802_11_AD_HOC_START firmware command, I need to tell
   this to cfg80211 somehow.

   cfg80211_ibss_joined() seems appropriate, but "iw event"
   doesn't show anything. Is this a short-coming or an indication
   of an error on my side?  Also, "iw wlan info" or "iw wlan link"
   doesn't show me anything at all.

b) the docs to cfg80211_ibss_joined() says that I need to call
   cfg80211_inform_bss() "with the locally generated beacon". I don't
   have any idea which beacon my firmware generates, so I guess I
   need to fake some beacon data. Correct?  Which IEs should I add?

c) cfg80211_inform_bss() has a field "signal". However, when I
   ask my firmware to start beacon, then I don't really have any
   signal level. If I add "0", then "iw wlan0 scan dump" shows me
   this as a signal:

   BSS 02:24:54:25:0f:24 (on wlan0)
        freq: 2412
        beacon interval: 100
        capability: IBSS (0x0002)
        signal: 0.00 dBm
        last seen: 6184 ms ago

d) And finally, for "u64 timestamp", is it okay to just submit
   a zero here?

-- 
http://www.holgerschurig.de

Re: cfg80211: questions regarding cfg80211_ibss_joined()

[Johannes Berg]

[-- Attachment #1: Type: text/plain, Size: 1665 bytes --]

On Tue, 2009-12-01 at 13:47 +0100, Holger Schurig wrote:
> Hi !
> 
> I'm currently adding IBSS to libertas+cfg80211. Now I'd like
> to get some clarifications:
> 
> a) when I create a new IBSS and i get a successful response to
>    the CMD_802_11_AD_HOC_START firmware command, I need to tell
>    this to cfg80211 somehow.
> 
>    cfg80211_ibss_joined() seems appropriate, but "iw event"
>    doesn't show anything. Is this a short-coming or an indication
>    of an error on my side?  Also, "iw wlan info" or "iw wlan link"
>    doesn't show me anything at all.

Are you running into the WARN_ON(!bss)?

> b) the docs to cfg80211_ibss_joined() says that I need to call
>    cfg80211_inform_bss() "with the locally generated beacon". I don't
>    have any idea which beacon my firmware generates, so I guess I
>    need to fake some beacon data. Correct?  Which IEs should I add?

As close to what your firmware is generating as you can get ...

> c) cfg80211_inform_bss() has a field "signal". However, when I
>    ask my firmware to start beacon, then I don't really have any
>    signal level. If I add "0", then "iw wlan0 scan dump" shows me
>    this as a signal:
> 
>    BSS 02:24:54:25:0f:24 (on wlan0)
>         freq: 2412
>         beacon interval: 100
>         capability: IBSS (0x0002)
>         signal: 0.00 dBm
>         last seen: 6184 ms ago

Eep. Yeah that seems like a bug, I guess for an IBSS we shouldn't be
adding the signal attribute at all.

> d) And finally, for "u64 timestamp", is it okay to just submit
>    a zero here?

Probably shouldn't be added for an IBSS either in nl80211.

johannes

[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 801 bytes --]

Re: cfg80211: questions regarding cfg80211_ibss_joined()

[Holger Schurig]

> Are you running into the WARN_ON(!bss)?

No, I didn't get a bug, warning nor any output.


In the mean-time I found that this was because I didn't provide 
any IE (I just submitted NULL & 0 to cfg80211_inform_bss).

Now I make a fake-IE with just WLAN_EID_SSID, and now I get 
some "iw event" output:

# iw event
wlan0 (phy #0): IBSS 02:2a:ea:f0:a5:ef joined




> >    need to fake some beacon data. Correct?  Which IEs should 
> >    I add?
> 
> As close to what your firmware is generating as you can get ...

Okay, will fire up wireshark :-)


-- 
http://www.holgerschurig.de