From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MDDoY-0000tD-Bm for qemu-devel@nongnu.org; Sun, 07 Jun 2009 04:33:14 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MDDoT-0000lY-Hj for qemu-devel@nongnu.org; Sun, 07 Jun 2009 04:33:13 -0400 Received: from [199.232.76.173] (port=49374 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MDDoT-0000l3-Ap for qemu-devel@nongnu.org; Sun, 07 Jun 2009 04:33:09 -0400 Received: from mail-fx0-f219.google.com ([209.85.220.219]:64140) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MDDoS-0008VR-W3 for qemu-devel@nongnu.org; Sun, 07 Jun 2009 04:33:09 -0400 Received: by fxm19 with SMTP id 19so2075594fxm.34 for ; Sun, 07 Jun 2009 01:33:07 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <4A2B6DD8.3090104@web.de> References: <4A26F1E3.1040509@codemonkey.ws> <4A2A92FE.2010700@redhat.com> <4A2AA10B.6060401@web.de> <4A2B49C0.8020703@redhat.com> <4A2B6DD8.3090104@web.de> Date: Sun, 7 Jun 2009 11:33:07 +0300 Message-ID: From: Blue Swirl Content-Type: text/plain; charset=UTF-8 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: =?UTF-8?Q?Andreas_F=C3=A4rber?= , Avi Kivity , "qemu-devel@nongnu.org" On 6/7/09, 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. I pulled qemu-kvm and it looks to me that KVM_CAP_DESTROY_MEMORY_REGION_WORKS and the derived functions kvm_destroy_memory_region_works() and must_use_aliases_*() are only used in very few places. Do I miss something, how can this be of any restriction?