sureshanaparti commented on PR #10964: URL: https://github.com/apache/cloudstack/pull/10964#issuecomment-3191255825
> Basically, Apache CloudStack allows operators to configure the CPU model that is exposed to VMs in KVM through three properties that can be defined in `agent.properties`: `guest.cpu.mode`, `guest.cpu.model` and `guest.cpu.features`. > > The `guest.cpu.mode` property accepts three possible values: > > * `custom`: Allows the customization of the CPU model, which should be defined in the `guest.cpu.model` setting. For instance: > ```shell > guest.cpu.mode=custom > guest.cpu.model=Skylake-Server > ``` > > > > > > > > > > > > The available models for a given architecture can be listed through the following command: > ```shell > virsh cpu-models <architecture> > ``` > * `host-model`: Libvirt identifies which model is more similar to the host's CPU model and adds extra features to approximate the host model as closely as possible. > * `host-passthrough`: Libvirt will communicate to KVM the exact characteristics of the host's CPU. The main difference from the `host-model` mode is that instead of pairing CPU flags, all the CPU details from the host are paired. > > The `guest.cpu.features` setting can be used to add or remove individual CPU features, for instance: > > ```shell > guest.cpu.mode=custom > guest.cpu.model=Skylake-Server > guest.cpu.features=aes mmx avx > ``` > > As can be noticed from the Agent logs that have been provided: > > ```shell > 2025-08-13 10:35:56,850 WARN [resource.wrapper.LibvirtStartCommandWrapper] (AgentRequest-Handler-2:[]) (logid:bfd1c45f) LibvirtException org.libvirt.LibvirtException: XML error: Non-empty feature list specified without CPU model > ``` > > Libvirt complains about specifying a list of flags without a CPU model. Therefore, to apply CPU flags in KVM, it is required to meet one of the following requirements: > > * Define `guest.cpu.mode=host-model` and specify the flags; > * Define `guest.cpu.mode=host-passthrough` and specify the flags; or, > * Define `guest.cpu.mode=custom`, `guest.cpu.model=<cpu-model>` and specify the flags. > > Otherwise, Libvirt will complain that a CPU model has not been specified. @bernardodemarco have you raised any doc PR with these details? if not, can you create one. thanks. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: commits-unsubscr...@cloudstack.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
