From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net-next 0/8] Add complementary BPF conditional jump instructions Date: Mon, 31 Dec 2012 14:37:15 -0800 (PST) Message-ID: <20121231.143715.1238174487756359071.davem@davemloft.net> References: Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: dborkman@redhat.com Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:54791 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751901Ab2LaWhQ (ORCPT ); Mon, 31 Dec 2012 17:37:16 -0500 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: From: Daniel Borkmann Date: Mon, 31 Dec 2012 14:59:40 +0100 > This set adds adds jump operations for lt (<), le (<=), ne (!=) that > compare A with K resp. X in order to facilitate filter programming > with conditional jumps, as also available in McCanne et. al's BPF+ > paper (``BPF+: Exploiting Global Data-flow Optimization in a Generalized > Packet Filter Architecture''). > > Also, follow-up BPF JIT implementations for x86, Sparc and PowerPC > are added in this set. Whilst I agree that adding NE jumps adds great value and closes a serious gap, the rest can be synthesized by simply swapping the arguments and using a comparison that does already exist. Why isn't that sufficient?