Re: [PATCH v2 1/4] conf: Introduce dynamicMemslots attribute for virtio-mem

On Wed, Jan 10, 2024 at 12:36:58 +0100, Michal Prívozník wrote: > On 1/8/24 10:00, David Hildenbrand wrote: >> On 08.01.24 09:38, Peter Krempa wrote: >>> On Fri, Jan 05, 2024 at 18:30:56 +0100, David Hildenbrand wrote: >>>> On 05.01.24 14:58, Peter Krempa wrote: >>>>> On Fri, Jan 05, 2024 at 14:34:53 +0100, David Hildenbrand wrote: >>>>>> On 05.01.24 13:40, Peter Krempa wrote: >>>>>>> On Fri, Jan 05, 2024 at 13:33:32 +0100, Michal Privoznik wrote: >>> >>> [...] >>> > > So what's the resolution here? IIUC, QEMU will enable this by default > and keep it off for older machine types. If that's the case, we don't > need these after all. Or am I misunderstanding something? So, at this point automatically enabling that feature is not possible as it makes the VM incompatible with 'vhost-user' devices, including ones hotplugged in the future. Based on the fact that it's about 'vhost-user' qemu won't be ever 100% sure that the possibly hotplugged device is modern enough to be compatible, as it depends on other software such as virtiofsd. As of such we will most likely need the flag as a workaround for when qemu decides to enable it, in case users want to use older software.