From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44289) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WjuQ9-0007R5-2M for qemu-devel@nongnu.org; Mon, 12 May 2014 13:53:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WjuQ1-0006vJ-Iu for qemu-devel@nongnu.org; Mon, 12 May 2014 13:53:49 -0400 Received: from cantor2.suse.de ([195.135.220.15]:34965 helo=mx2.suse.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WjuQ1-0006v6-D7 for qemu-devel@nongnu.org; Mon, 12 May 2014 13:53:41 -0400 Message-ID: <53710AA2.3080808@suse.de> Date: Mon, 12 May 2014 19:53:38 +0200 From: =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= MIME-Version: 1.0 References: <1399630869-920-1-git-send-email-arei.gonglei@huawei.com> <20140509111807.GA22335@work-vm> <1399636479.5213.56.camel@nilsson.home.kraxel.org> <5370FF54.2080808@redhat.com> In-Reply-To: <5370FF54.2080808@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH] cirrus_vga: adding sanity check for vram size List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake Cc: Alexander Graf , weidong.huang@huawei.com, mst@redhat.com, "libvir-list@redhat.com" , qemu-devel@nongnu.org, "Dr. David Alan Gilbert" , Jim Fehlig , arei.gonglei@huawei.com, Gerd Hoffmann , pbonzini@redhat.com -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Am 12.05.2014 19:05, schrieb Eric Blake: > [adding libvirt] >=20 > On 05/09/2014 05:54 AM, Gerd Hoffmann wrote: >> Hi, >>=20 >>> virt-manager/libvirt seems to default to 9 MByte of Vram for >>> cirrus, so this would break a lot of setups. >>=20 >> It wouldn't. libvirt sticks that into the xml, but it doesn't >> set any qemu parameters. The libvirt parameter actually predates >> the qemu property for setting the size. D=C3=A9j=C3=A0 vu... we had the same problem with pvpanic. > Then we should probably re-evaluate what libvirt does with the=20 > parameters, which avoids breaking any guest that happens to be=20 > pre-existing with the odd 9MB sizing in the XML. If libvirt cannot or doesn't want to pass a user-supplied tag to QEMU, the only sane and future-proof solution is for libvirt to signal an error to the user for *any* flags it cannot handle rather than throwing up on a case-by-case basis the question of how libvirt should behave when some previously ignored feature gets implemented. That would prevent us from running into this situation again and again. As further examples, apic, acpi and other x86-centric features got auto-added for s390x guests last time I checked. Apart from anything the user might have specified herself, there's really no reason to add stuff the user did not ask for and that are not applicable. Ignoring a value "9" specified by the user would be very odd; and I guess you have no way of telling who added what to the XML for choosing between dropping and error'ing out. Regards, Andreas - --=20 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=C3=BCrnberg, Germany GF: Jeff Hawn, Jennifer Guild, Felix Imend=C3=B6rffer; HRB 16746 AG N=C3=BC= rnberg -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQIcBAEBAgAGBQJTcQqiAAoJEPou0S0+fgE/CY8P/jRgyfqNtv2MLbilNXKKXe5A CBftFQv1dlvL4VFVGD9W5ortlyOpPfxSmC6fgnLKNbTsTCtDy1k3zgWp8uSjYNrp /W5oMpOstYxUBA7LtizCnCyPisffV6FlWQBLt8BGnRBPjEyVQXIIDHQuwvYv6Byr EKjCGWMjw76Rfe84Hdl7xDQvfd+qTFjIDbKEfSa3fciJ/svCYKlnTqsPzvtNWbUg 907r5tI2LVT17xaclhex12GQ+uxV4hXcpcUnY3W/lCHvH98NdgFZRf1P8xTdjSmB MbQ6WKOtGK9SqoyPiPzm8NwPduBbbmC69vumEmaG6QCqvTmcEKPNB5WMcXSEo4YB SBJjZrkeNgS7XlUDwL4i45PYSbxi60CByrIrvYzWEielPCUQWMKzckfs+Zxmu0FT nO51q334YmHU1X/oEPDnF8hakwzu9figWJ43uXSP/dm3ifjhFh35/Owmz+pd84Zi cauzlygF0JAHGKurStveIqOZ0o6AJLxhWZP695PbKHAeHvOXo6dSsnLgG6POylP1 N/pTCcvQZV6oZ/NjscHcrmYxwrA4XWSzY8JdzS4iPSqzvCgxFNR/wZ1VTjCZ5Cbx zs+bv+B7JKhjrYs/7dQt8kPv5ZXwh/kEkxkhXX7xpBfdPixx173Gdg3XvS86G6GI q/dszTpb4kJNcsaxNp3y =3DRZ98 -----END PGP SIGNATURE-----