From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MDE5Z-0003wA-Oj for qemu-devel@nongnu.org; Sun, 07 Jun 2009 04:50:49 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MDE5V-0003vy-PN for qemu-devel@nongnu.org; Sun, 07 Jun 2009 04:50:49 -0400 Received: from [199.232.76.173] (port=56694 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MDE5V-0003vv-LK for qemu-devel@nongnu.org; Sun, 07 Jun 2009 04:50:45 -0400 Received: from fmmailgate01.web.de ([217.72.192.221]:43783) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MDE5V-0002wV-2c for qemu-devel@nongnu.org; Sun, 07 Jun 2009 04:50:45 -0400 Message-ID: <4A2B7F5E.8050807@web.de> Date: Sun, 07 Jun 2009 10:50:38 +0200 From: Jan Kiszka 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: Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig7BF53BF0ED093BB6782065D2" Sender: jan.kiszka@web.de 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: Blue Swirl Cc: =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= , Avi Kivity , "qemu-devel@nongnu.org" This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig7BF53BF0ED093BB6782065D2 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Blue Swirl wrote: > On 6/7/09, Jan Kiszka wrote: >> Avi Kivity wrote: >> > Jan Kiszka wrote: >> >>> Maybe the backwards compatibility features should be ported to QE= MU? >> >>> 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 suppor= t down >> >> to reasonable kernel versions, I would prefer to keep upstream cle= an >> >> from old workarounds. They should only be needed for issues found = very >> >> recently (KVM_CAP_JOIN_MEMORY_REGIONS_WORKS) or that might be foun= d in >> >> the future. >> >> >> > >> > Requiring the latest up-to-date modules is pushing the problem to t= he >> > 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 compara= ble >> 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 m= ost >> 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 workarou= nds >> 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 unl= ess >> something more problematic comes along (rather unlikely), 2.6.29 or >> compatible kvm-kmod is a reasonable minimum requirement for the long = term. >=20 > 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? Check e.g the diff of hw/vga.c against upstream: All the magic dances there are required as qemu-kvm tracking cpu_register_physical_memory and kvm_log_start cannot cope with all the patterns normal qemu code comes up with. Upstream slot management now provides the same features (including migration) like qemu-kvm, it just does not deal with legacy, thus it does not have to patch qemu code (rather, we were able to remove some already merged hooks - vga_dirty_log_stop). Jan --------------enig7BF53BF0ED093BB6782065D2 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org iEYEARECAAYFAkorf2IACgkQniDOoMHTA+mdygCeKE4S9UrEzIv9aaCoElX4Lvvi 6xEAn10srxgUDd8CIoB5p6ubRgZ4FrXa =Cdqv -----END PGP SIGNATURE----- --------------enig7BF53BF0ED093BB6782065D2--