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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-TM-AS-GCONF: 00 x-cbid: 19112612-4275-0000-0000-0000038696C2 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19112612-4276-0000-0000-0000389A211C Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,18.0.572 definitions=2019-11-26_03:2019-11-26,2019-11-26 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 phishscore=0 impostorscore=0 mlxscore=0 clxscore=1015 spamscore=0 suspectscore=0 priorityscore=1501 malwarescore=0 lowpriorityscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1910280000 definitions=main-1911260116 Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by mx0b-001b2d01.pphosted.com id xAQCx4ck147451 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] [fuzzy] X-Received-From: 148.163.158.5 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Thomas Huth , =?UTF-8?Q?Daniel_P_=2e_Berrang=c3=a9?= , Janosch Frank , Cornelia Huck , Richard Henderson , qemu-devel@nongnu.org, Markus Armbruster , Halil Pasic , qemu-s390x@nongnu.org, Jiri Denemark , Eduardo Habkost Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" re-adding ccs from the cover-letter >>> On 25.11.19 18:20, David Hildenbrand wrote: >>> >>> As soon as dynamic feature groups are used, the CPU model becomes >>> migration-unsafe. Upper layers can expand these models to migration-s= afe >>> and static variants, allowing them to be migrated. >> >> I really dislike that. I am trying to get rid of the unsafe variants (= e.g. now >> defaulting to host-model instead of host-passthrough). I do not want t= o give >> users new ways of hurting themselves. >> >=20 > Please note that this is just on the bare command line. Libvirt and fri= ends will expand the model and have proper migration in place. What exact= ly is your concern in that regard? What is then the value? libvirt can also use host-model or baselining if= necessary. And for the command line this will just add more opportunity to shot your= self in the foot, no? Let me put it this way, I might have misunderstood what you are trying to= do here, but if I do not get, then others (e.g. users) will also not get it. Maybe its just the interface or the name. But I find this very non-intuit= ive e.g. you wrote Get the maximum possible feature set (e.g., including deprecated features) for a CPU definition in the configuration ("everything that could be enabled"): -cpu z14,all-features=3Doff,available-features=3Don Get all valid features for a CPU definition: -cpu z14,all-features=3Don What is the point of this? It is either the same as the one before, or it= wont be able to start.=20 >=20 >> Unless I misunderstood Eduardo, I think his versioning approach is act= ually better >> in regard to migration, no? >> I z terms, you can still say -cpu z13 which is just an alias to z13v1= z13v2 etc. >> Assuming that the version is checked this will be safe. >> >=20 > It=E2=80=98s even worse AFAIKS. A =E2=80=9E-cpu z13=E2=80=9C would dyna= mically map to whatever is best on the host. >=20