From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by dpdk.org (Postfix) with ESMTP id 567052A5B for ; Wed, 22 Apr 2015 10:59:55 +0200 (CEST) Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga103.jf.intel.com with ESMTP; 22 Apr 2015 01:59:53 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.11,622,1422950400"; d="scan'208";a="699047279" Received: from irsmsx106.ger.corp.intel.com ([163.33.3.31]) by fmsmga001.fm.intel.com with ESMTP; 22 Apr 2015 01:59:53 -0700 Received: from irsmsx109.ger.corp.intel.com ([169.254.13.201]) by IRSMSX106.ger.corp.intel.com ([169.254.8.204]) with mapi id 14.03.0224.002; Wed, 22 Apr 2015 09:59:52 +0100 From: "Burakov, Anatoly" To: Stephen Hemminger Thread-Topic: [dpdk-dev] [PATCH] vfio: don't silently drop VFIO support Thread-Index: AQHQe5iKlnF3SJ8U8Uu+6UqyJsRwB51XNKrwgAB2XICAARD/gA== Date: Wed, 22 Apr 2015 08:59:51 +0000 Message-ID: References: <1429554771-32365-1-git-send-email-stephen@networkplumber.org> <20150421103459.6b8094d0@urahara> In-Reply-To: <20150421103459.6b8094d0@urahara> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [163.33.239.181] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Cc: "dev@dpdk.org" Subject: Re: [dpdk-dev] [PATCH] vfio: don't silently drop VFIO support 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: Wed, 22 Apr 2015 08:59:55 -0000 Hi Stephen, > > Hi Stephen, > > > > > The VFIO_PRESENT #define was a landmine and we hit it. > > > The DPDK has a config system and it should be used rather than > > > silently dropping a feature during build only to have it fail at run = time. > > > > > > If VFIO is configured, and the kernel headers are not present the > > > build should fail. Rather than leaving developers puzzling why the > > > build system (with old kernel headers) produced non functioning DPDK > > > and their system (with new kernel headers) produced correctly working > DPDK. > > > > > > As a matter of policy, really no code should be looking at > > > except for kernel drivers with compat files. > > > > In theory, I agree with you. In practice however, this change will > unconditionally break builds on pre-VFIO kernels (<3.6). >=20 > If someone is building with an older kernel, then they should change the > config. >=20 Well, it's not like this is immediately obvious to anyone building DPDK. Wi= th your patch, the "out-of-the-box" experience is no longer there, since on= e now has to figure out why it's not building, go edit config files, et al,= which is easy for you and me, but may not be easy for someone dealing with= DPDK for the first time. I agree that both situations aren't ideal, it just seems to me that not bui= lding VFIO by default is better in that sense (EAL will show a warning mess= age saying that VFIO isn't enabled, but the code will actually compile). Of= course, the best of both worlds would be something like a configure script= . Thanks, Anatoly