Return-path: Received: from mail-bw0-f46.google.com ([209.85.214.46]:53786 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933731Ab1JZRxc (ORCPT ); Wed, 26 Oct 2011 13:53:32 -0400 Received: by bkbzt19 with SMTP id zt19so1840120bkb.19 for ; Wed, 26 Oct 2011 10:53:31 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <4EA7DA0F.7050603@sipsolutions.net> References: <1319350901-31178-1-git-send-email-arik@wizery.com> <4EA7DA0F.7050603@sipsolutions.net> From: Arik Nemtsov Date: Wed, 26 Oct 2011 19:53:16 +0200 Message-ID: (sfid-20111026_195342_915623_025BCD71) Subject: Re: [PATCH] mac80211: support adding IV-room in the skb for CCMP keys To: Johannes Berg Cc: linux-wireless@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Wed, Oct 26, 2011 at 11:59, Johannes Berg wrote: > On 10/23/2011 8:21 AM, Arik Nemtsov wrote: >> >> Some cards can generate CCMP IVs in HW, but require the space for the IV >> to be pre-allocated in the frame at the correct offset. Add a key flag >> that allows us to achieve this. > > Is it really that expensive to generate the IV and then not use it that this > is worth the extra complexity? This not just makes it more complex but also > more expensive in the other case. > Some of the platforms with this chip are pretty weak (host CPU is the bottleneck). We add another "if" for the other case (for a value that's likely in the cacheline already). I don't think that's too bad. Arik