From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:33041) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QHJZL-0003r5-0r for qemu-devel@nongnu.org; Tue, 03 May 2011 13:39:32 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QHJZJ-0000bN-OI for qemu-devel@nongnu.org; Tue, 03 May 2011 13:39:30 -0400 Received: from thoth.sbs.de ([192.35.17.2]:18564) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QHJZJ-0000b2-DW for qemu-devel@nongnu.org; Tue, 03 May 2011 13:39:29 -0400 Message-ID: <4DC03DCD.30103@siemens.com> Date: Tue, 03 May 2011 19:39:25 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <4DC00BB1.7000008@siemens.com> <4DC031CC.1040902@siemens.com> <4DC0336B.7020106@redhat.com> <4DC036AD.7070306@siemens.com> <4DC037A0.2090507@redhat.com> <20110503173200.GA30864@laped.lan> In-Reply-To: <20110503173200.GA30864@laped.lan> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2] Import Linux headers for KVM and vhost List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Edgar E. Iglesias" Cc: Anthony Liguori , kvm , Marcelo Tosatti , Alexander Graf , qemu-devel , Avi Kivity On 2011-05-03 19:32, Edgar E. Iglesias wrote: > On Tue, May 03, 2011 at 08:13:04PM +0300, Avi Kivity wrote: >> On 05/03/2011 08:09 PM, Jan Kiszka wrote: >>>> >>>> Reluctant ack. >>> >>> What downsides do you see? >> >> The usual "it shouldn't be this way". Every other package (including, I >> think, glibc) uses the sanitized system headers. Except for kvm-kmod, >> the system headers are always available. > > I agree, it doesn't feel quite right to bring in the headers. I don't have > any alternative suggestions (besides better HOWTOs/Documentation) though. Again, the downside of the current approach are: - outdated distro headers silently disable features during build time (happened to me with vhost e.g.) - build breakages against older kernels / headers are pre-programmed as hardly anyone tests all the possible combinations - tons of #ifdef in the code + configure checks to catch the possible combinations Also note that [1] recommends this approach as well. I'm not aware of good examples, but I would be fairly surprised if we were the first to do this. Jan [1] http://kernelnewbies.org/KernelHeaders -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux