From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MDD5F-0000FX-0r for qemu-devel@nongnu.org; Sun, 07 Jun 2009 03:46:25 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MDD59-00008G-7Z for qemu-devel@nongnu.org; Sun, 07 Jun 2009 03:46:23 -0400 Received: from [199.232.76.173] (port=46963 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MDD59-000082-25 for qemu-devel@nongnu.org; Sun, 07 Jun 2009 03:46:19 -0400 Received: from mx2.redhat.com ([66.187.237.31]:47950) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MDD58-0000IK-Es for qemu-devel@nongnu.org; Sun, 07 Jun 2009 03:46:18 -0400 Message-ID: <4A2B7042.5070005@redhat.com> Date: Sun, 07 Jun 2009 10:46:10 +0300 From: Avi Kivity MIME-Version: 1.0 References: <4A26F1E3.1040509@codemonkey.ws> <4A2A92FE.2010700@redhat.com> <4A2AA10B.6060401@web.de> <4A2B49C0.8020703@redhat.com> <4A2B6DD8.3090104@web.de> In-Reply-To: <4A2B6DD8.3090104@web.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: POLL: Why do you use kqemu? List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: Blue Swirl , =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= , "qemu-devel@nongnu.org" Jan Kiszka wrote: > Avi Kivity wrote: > >> Jan Kiszka wrote: >> >>>> Maybe the backwards compatibility features should be ported to QEMU? >>>> For example, is there a workaround for >>>> #error Missing KVM capability KVM_CAP_DESTROY_MEMORY_REGION_WORKS >>>> ? >>>> >>>> >>> Given that we have always-up-to-date kvm-kmod packages with support down >>> to reasonable kernel versions, I would prefer to keep upstream clean >>> from old workarounds. They should only be needed for issues found very >>> recently (KVM_CAP_JOIN_MEMORY_REGIONS_WORKS) or that might be found in >>> the future. >>> >>> >> Requiring the latest up-to-date modules is pushing the problem to the >> users. Sometimes there is no choice, but when there is, the >> implementation that cares about its uses prefer unclean code and >> functionality over perfection and brokenness. >> > > Let's make it more concrete: > > By the time upstream is as well tested, feature-rich and with comparable > performance as qemu-kvm, its current baseline requirement (2.6.29 due to > KVM_CAP_DESTROY_MEMORY_REGION_WORKS) will no longer be a problem to most > normal users. Until then they are better off with qemu-kvm anyway. > > So all I wanted to express is that I see no point in merging workarounds > upstream that hardly anyone will need but that restrict non-kvm code in > upstream. Basically I have the current line along > KVM_CAP_DESTROY_MEMORY_REGION_WORKS / clean memory slot management in > mind. Anything older should be skipped when merging upstream. And unless > something more problematic comes along (rather unlikely), 2.6.29 or > compatible kvm-kmod is a reasonable minimum requirement for the long term. > If you put it that way, I agree. It's reasonable for qemu.git to target 2.6.29.latest, unless it starts gaining features very rapidly. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.