From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Kahn Gillmor Subject: Re: Misalignment, MIPS, and ip_hdr(skb)->version Date: Wed, 07 Dec 2016 23:34:21 -0500 Message-ID: <87vauvhwdu.fsf@alice.fifthhorseman.net> References: <095cac5b-b757-6f4a-e699-8eedf9ed7221@stressinduktion.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: LKML , WireGuard mailing list To: Hannes Frederic Sowa , "Jason A. Donenfeld" , Netdev , linux-mips@linux-mips.org Return-path: In-Reply-To: <095cac5b-b757-6f4a-e699-8eedf9ed7221@stressinduktion.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: wireguard-bounces@lists.zx2c4.com Sender: "WireGuard" List-Id: netdev.vger.kernel.org On Wed 2016-12-07 19:30:34 -0500, Hannes Frederic Sowa wrote: > Your custom protocol should be designed in a way you get an aligned ip > header. Most protocols of the IETF follow this mantra and it is always > possible to e.g. pad options so you end up on aligned boundaries for the > next header. fwiw, i'm not convinced that "most protocols of the IETF follow this mantra". we've had multiple discussions in different protocol groups about shaving or bloating by a few bytes here or there in different protocols, and i don't think anyone has brought up memory alignment as an argument in any of the discussions i've followed. that said, it sure does sound like it would make things simpler to construct the protocol that way :) --dkg