From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-ew0-f224.google.com ([209.85.219.224]:41358 "EHLO mail-ew0-f224.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750869AbZEDRFx (ORCPT ); Mon, 4 May 2009 13:05:53 -0400 Received: by ewy24 with SMTP id 24so4131580ewy.37 for ; Mon, 04 May 2009 10:05:52 -0700 (PDT) From: Ivo van Doorn To: Johannes Berg Subject: Re: IEEE80211 Acknowledgement Date: Mon, 4 May 2009 19:05:44 +0200 Cc: Alexandre Becholey , linux-wireless@vger.kernel.org References: <49FF06BB.2090106@shockfish.com> <200905041855.17435.IvDoorn@gmail.com> <1241456546.8683.67.camel@johannes.local> In-Reply-To: <1241456546.8683.67.camel@johannes.local> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15" Message-Id: <200905041905.44646.IvDoorn@gmail.com> Sender: linux-wireless-owner@vger.kernel.org List-ID: 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