From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net-next 1/9] bpf: add BPF_J{LT,LE,SLT,SLE} instructions Date: Wed, 09 Aug 2017 14:26:00 -0700 (PDT) Message-ID: <20170809.142600.872268659837843440.davem@davemloft.net> References: <598B3FCA.7060904@iogearbox.net> <20170809.110128.709552645127117641.davem@davemloft.net> <598B7162.90509@iogearbox.net> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: ast@fb.com, holzheu@linux.vnet.ibm.com, naveen.n.rao@linux.vnet.ibm.com, jakub.kicinski@netronome.com, netdev@vger.kernel.org To: daniel@iogearbox.net Return-path: Received: from shards.monkeyblade.net ([184.105.139.130]:46230 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752066AbdHIV0B (ORCPT ); Wed, 9 Aug 2017 17:26:01 -0400 In-Reply-To: <598B7162.90509@iogearbox.net> Sender: netdev-owner@vger.kernel.org List-ID: From: Daniel Borkmann Date: Wed, 09 Aug 2017 22:32:34 +0200 > For the case of cilium, we are not in control of the kernel, by > the way, we run a few probes that are small BPF insns snippets > that test the kernel for presence of certain features (e.g. helper, > verifier, maps) and enable/disable them accordingly later in the > code generation. On the user space side, we're indeed a bit more > flexible and have no such restriction. > > Plan is for LLVM as one of the frontends that generate byte code > (ply, for example, can probe the kernel directly for its code > generation) to have i) a target specific option to offer a > possibility to explicitly enable the extension by the user (as we > have with -m target specific extensions today for various cpu > insns), and ii) have the kernel check for presence of the extensions > and enable it transparently when the user selects more aggressive > options such as -march=native in a bpf target context, so we can > select the underlying features transparently. I should have made > that more clear earlier, sorry about that. I think this explanation needs to be in either your header posting or the commit message of patch #1. Thanks :)