From mboxrd@z Thu Jan 1 00:00:00 1970 From: Olivier Subject: Re: Dscape ieee80211: enabling/disabling the radio Date: Wed, 10 May 2006 07:29:55 +0200 Message-ID: <7b4bf7ff0605092229p7a8f1bd5j5ebca4d59ceda381@mail.gmail.com> References: <200605061401.01795.IvDoorn@gmail.com> <200605100001.20180.IvDoorn@gmail.com> <200605091836.10138.flamingice@sourmilk.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7BIT Cc: "Ivo van Doorn" , netdev@vger.kernel.org, "Jiri Benc" Return-path: Received: from nf-out-0910.google.com ([64.233.182.186]:34727 "EHLO nf-out-0910.google.com") by vger.kernel.org with ESMTP id S964789AbWEJF34 convert rfc822-to-8bit (ORCPT ); Wed, 10 May 2006 01:29:56 -0400 Received: by nf-out-0910.google.com with SMTP id b2so1344173nfe for ; Tue, 09 May 2006 22:29:55 -0700 (PDT) To: "Michael Wu" In-Reply-To: <200605091836.10138.flamingice@sourmilk.net> Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 2006/5/10, Michael Wu : > On Tuesday 09 May 2006 18:01, Ivo van Doorn wrote: > > A user on the forums Olivier Cornu (added to the CC list) has done some > > investigation into the scanning behaviour of the dscape stack. > > Basicly the dscape stack is performing active scanning while the device is > > down, but during the active scan it is sending packets out, or at least > > attempting to do so. Besides the question if active scanning is preferred > > over passive scanning while interface is down, active scanning fails > > because the packets that should be send are being send through the regular > > xmit routines of the interface. (IFF_UP is not set for the interface) > > > > This means that besides enabling the radio which should be done in the > > driver, the stack should either bring up the interface when doing an active > > scan, or resort to passive scanning while interface is down. > > > If you can passive scan while the interface is down, I don't think it's really > down. In adm8211, nothing can be sent or received when the interface is down. > The radio is always off when the interface is down. Taking the interface up > just for a scan and then taking it back down doesn't sound too good either. I > think scans should be prohibited while the interface is down, since leaving > the interface on isn't gonna do anything bad unless you put in the info to > associate. > > -Michael Wu > What do you mean exactly by "device is down, but not really down"? I thought a network device was called "down" when the IFF_UP flag of its net_device struct was set to 0 (thus not appearing in ifconfig, among other things). Is there any other alternative understanding of it being "down" i'm not aware of? I confirm scanning actively with the device down is possible using another NIC/driver. Thus I guess it's normal behaviour. I still have to figure out how to do it using the dscape 802.11 stack (if it's actually possible)... Olivier Cornu