From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from smtp1.infomaniak.ch ([84.16.68.89]:46112 "EHLO smtp1.infomaniak.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751807AbZEEHoR (ORCPT ); Tue, 5 May 2009 03:44:17 -0400 Message-ID: <49FFEE42.3080102@shockfish.com> Date: Tue, 05 May 2009 09:44:02 +0200 From: Alexandre Becholey MIME-Version: 1.0 To: Ivo van Doorn CC: Johannes Berg , linux-wireless@vger.kernel.org Subject: Re: IEEE80211 Acknowledgement References: <49FF06BB.2090106@shockfish.com> <200905041855.17435.IvDoorn@gmail.com> <1241456546.8683.67.camel@johannes.local> <200905041905.44646.IvDoorn@gmail.com> In-Reply-To: <200905041905.44646.IvDoorn@gmail.com> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Sender: linux-wireless-owner@vger.kernel.org List-ID: Ivo van Doorn wrote: > On Monday 04 May 2009, Johannes Berg wrote: > >> On Mon, 2009-05-04 at 18:55 +0200, Ivo van Doorn wrote: >> >>> On Monday 04 May 2009, Johannes Berg wrote: >>> >>>> On Mon, 2009-05-04 at 18:35 +0200, Ivo van Doorn wrote: >>>> >>>> >>>>> Well I believe the idea would be that (I'll see if I can dig up a reference >>>>> to the initial discussion about this feature on this list) the driver sets a flag >>>>> that mac80211 needs to keep a list of all frames send out to the driver and >>>>> listens for ACK's. >>>>> >>>>> As soon as a ACK was passed from driver to mac80211 it could check if >>>>> the corresponding frame >>>>> >>>> ^^^^^^^^^^^^^^^^^^^ >>>> >>>> Here's the problem. What I'm saying is that there's no way to knowing >>>> what the "corresponding frame" is. >>>> >>> Hmm, so would there be any alternatives of fixing this problem? >>> >> The proper way of fixing this would be a firmware upgrade ;) >> >> Working around it would be possible if the driver queued only a single >> frame to the hardware, when it knew the frame needed ACK status, and >> flushed all queues before that frame, so it knows exactly about the >> frame... This has HUGE overhead and performance impact though, and >> requires lots of work in mac80211 to not request status for every frame >> to start with. >> >> Since this breaks hostapd operation quite significantly, and I don't see >> hostapd changing to accommodate this since that essentially breaks the >> ability to be spec compliant (I'm fairly certain some places require >> checking for ACK). >> >> An easier way would be to fake a ACK reception in the driver for every >> frame... >> > > Ok, well I'll go with this route then. Since firmware upgrades for > older hardware like rt73usb sounds very unlikely. And for rt2500usb > it is plain impossible (no firmware ;)) > > Alexandre: Well that seems to make your project a lot easier... > > Ivo > Thanks for your answers! I'm gonna try it that way :) Alexandre