From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id 889F6A04C8; Fri, 18 Sep 2020 14:54:24 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id DB3E91DA63; Fri, 18 Sep 2020 14:54:23 +0200 (CEST) Received: from vps27536.dedimax.com (hawari.fr [176.31.211.215]) by dpdk.org (Postfix) with ESMTP id 58CF81DA61 for ; Fri, 18 Sep 2020 14:54:23 +0200 (CEST) Received: from [10.61.170.176] (unknown [173.38.220.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: momohawari) by vps27536.dedimax.com (Postfix) with ESMTPSA id 1521FBA061F; Fri, 18 Sep 2020 14:54:23 +0200 (CEST) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.120.23.2.1\)) From: Mohammed Hawari In-Reply-To: <20200918114329.GA1589@bricha3-MOBL.ger.corp.intel.com> Date: Fri, 18 Sep 2020 14:54:21 +0200 Cc: dev@dpdk.org Content-Transfer-Encoding: quoted-printable Message-Id: <33FE1BDE-C31E-4879-836B-DA22C850B829@hawari.fr> References: <20200918084924.31784-1-mohammed@hawari.fr> <20200918084924.31784-2-mohammed@hawari.fr> <20200918114329.GA1589@bricha3-MOBL.ger.corp.intel.com> To: Bruce Richardson X-Mailer: Apple Mail (2.3608.120.23.2.1) Subject: Re: [dpdk-dev] [PATCH 1/1] build: allow disabling libs X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Hello Bruce, Thanks for the quick response, see inline Best regards, Mohammed > On 18 Sep 2020, at 13:43, Bruce Richardson = wrote: >=20 > On Fri, Sep 18, 2020 at 10:49:23AM +0200, Mohammed Hawari wrote: >> Similarly to the disable_drivers option, the disable_libs option is >> introduced. This allows to selectively disable the build of elements >> in libs to speed-up the build process. >>=20 >> Signed-off-by: Mohammed Hawari >> --- >=20 > While I don't particularly like allowing libs to be enabled and = disabled > since it complicates the build, I can see why it's necessary. This is = an > area that does need some discussion, as I believe others have some = opinions > in this area too. >=20 > However, for now, some additional thoughts, both on this patch and in > general: >=20 > 1. I see you included disabling apps if their required libs are not > available. What about the drivers though? To my understanding, in the current code, the drivers/meson.build file = already does that check with: foreach d:deps if not is_variable('shared_rte_' + d) build =3D false > 2. A bigger issue is whether this is really what we want to do, = guarantee a > passing build even if vast chunks of DPDK are actually enabled? I'd = tend > towards "no" in this case, and I'd rather see disabling of libs more > constrained. > 3. To this end, I think I'd rather see us maintain a set of libs which = are > allowed to be disabled, and prevent the rest from being so. For = example, > it makes no sense in DPDK to disable the EAL or mempool libs, since = nothing > will build, while the bitrate_stats or latency_stats libs could = likely > be disabled with little or no impact. I tend to agree with that more structured approach, but I am going to = wait until we get some more thoughts from the community before starting that work. > Therefore, I think a better implementation is to start as in this = patch > with a new config parameter to disable libs, but as part of that patch = add > in an internal list of the libs which are allowed to be disabled = (initially > empty). Telling the build system to disable a lib not on that list = should > raise a configuration time error. As for how a lib gets on the list - = that > should be done once the build has been tested with that lib disabled, = i.e. > once testpmd and other apps have got #defines in the code for = stripping out > the disabled blocks, and any drivers which depend on the lib have = proper > checks and warnings in place about it being disabled (or also #defines = in > the code if that can be done). >=20 > The other advantage of maintaining such a list is that it then becomes > somewhat feasible to test these build settings, in that (maybe once = per > release), iterate through the list of disable-able libs and test that = the > build passed with each one disabled individually. [I think for this = purpose > we can ignore interactions of having two disabled simultaneously, in = order > to have something testable] >=20 > What do others in the community think? >=20 > Regards, > /Bruce