From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f42.google.com (mail-wg0-f42.google.com [74.125.82.42]) by dpdk.org (Postfix) with ESMTP id 88607C406 for ; Fri, 10 Jul 2015 22:21:07 +0200 (CEST) Received: by wgov12 with SMTP id v12so73073120wgo.1 for ; Fri, 10 Jul 2015 13:21:07 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:organization :user-agent:in-reply-to:references:mime-version :content-transfer-encoding:content-type; bh=1mQmxqZUDNbGBWlW+U7P9RPBDDcJSDrcNlnlyeblcSg=; b=GKU8RwcL+4aGvA/Rs3kvCJKXjkMuCVUZq2uVrl1ggWAVdn9C2LRgcHUjg2ZWtXvXtw xKAQkY3xkh36y9JlO8kS97WU163Znt9I/RQ/AhDKOK6Nz6iLaTjRL1F6wtSOzOFfa0Tf UfXMW6oVGdELzqYgTNrNyf9AR3BOLr+79bEupUtZePOkFSlqxBK0hVNJl6nuzkcBw5gu CNJTqL3Bl8N5hGX6n1uEatJEgRyBdDiNVy5a/swIqSpv97naKHX6gdUMRq3I0QlXYYYd ZFYGMjIapFo1PQpgp3SHYY42XDL567LfG5eZGmMoQnPlUyd0sGf3WzbKakRrmlLrkyM2 mB9g== X-Gm-Message-State: ALoCoQnzqqqfeZoTwGUYHhdsoYaK67Ok/5Fl5tJXhd0SLUv3yFEwBCv+yERoqAE6dROcyEyIJbNo X-Received: by 10.194.60.81 with SMTP id f17mr43434615wjr.62.1436559667381; Fri, 10 Jul 2015 13:21:07 -0700 (PDT) Received: from xps13.localnet (136-92-190-109.dsl.ovh.fr. [109.190.92.136]) by smtp.gmail.com with ESMTPSA id wx9sm15097551wjb.6.2015.07.10.13.21.05 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 10 Jul 2015 13:21:06 -0700 (PDT) From: Thomas Monjalon To: Stephen Hemminger Date: Fri, 10 Jul 2015 22:19:58 +0200 Message-ID: <6809322.q4mZEddvC3@xps13> Organization: 6WIND User-Agent: KMail/4.14.8 (Linux/4.0.4-2-ARCH; KDE/4.14.8; x86_64; ; ) In-Reply-To: <20150710102914.3db19e8a@urahara> References: <1436484387-29273-1-git-send-email-stephen@networkplumber.org> <2141795.rDVNFltQvv@xps13> <20150710102914.3db19e8a@urahara> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Cc: dev@dpdk.org, Stephen Hemminger Subject: Re: [dpdk-dev] [PATCH v2 1/2] vfio: fix build if build envrionment is on old kernel X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 10 Jul 2015 20:21:07 -0000 2015-07-10 10:29, Stephen Hemminger: > On Fri, 10 Jul 2015 01:43:17 +0200 > Thomas Monjalon wrote: > > > 2015-07-09 16:26, Stephen Hemminger: > > > From: Stephen Hemminger > > > > > > The build of DPDK may be done on a system where Linux headers > > > in /usr/include (and therefore kernel version macro) are much > > > older than the target runtime system. > > > > It seems strange wanting to build a feature not present in the kernel > > headers. Why not upgrading the build system kernel? > > The build machine is running Debian with stock headers and kernel. > I can see many people having build environments controlled by other > parts of organization where you are not allowed to update packages. > > > > In order to work around this, one solution is to put in simplified > > > kernel header (this is what the compat stuff is already doing). > > > > The other solution (as already suggested by Anatoly) is to have a configure > > script (not an autotool one). It would make clear that VFIO support is not > > built. > > Ref: http://dpdk.org/ml/archives/dev/2015-April/016772.html > > That won't solve the issue. That allows to see the error earlier and more clearly. > The other possiblities are: > 1. Fail the build if VFIO is configured but headers files are missing. > This is better than surprising user at runtime. > 2. Don't use /usr/include/linux as path as expected path of kernel headers > instead use build path (this is what modules do). The latter one seems to be the right one. There is a name for that technique: cross-compilation. If you want to build DPDK to run on another system with different kernel and libraries, you should adapt the toolchain and libraries headers. And guess what? include/linux/ is part of this toolchain. Problem solved.