On Wed, Apr 27, 2022 at 14:11:23 +0800, Jiatong Shen wrote:

Hello libvirt experts,

I am facing the following exceptions during live migrating a virtual machine from one compute node to another.

file or directory: libvirt.libvirtError: Cannot check QEMU binary /usr/bin/kvm-spice: No such file or directory File "/var/lib/openstack/lib/python3.6/site-packages/eventlet/tpool.py", line 83, in tworker rv = meth(*args, **kwargs) File "/var/lib/openstack/lib/python3.6/site-packages/libvirt.py", line 1745, in migrateToURI3 if ret == -1: raise libvirtError ('virDomainMigrateToURI3() failed', dom=self) libvirt.libvirtError: Cannot check QEMU binary /usr/bin/kvm-spice: No such file or directory

After some investigation, we found that this error is triggered because we do not have qemu-kvm installed in our container, btw the libvirt is directly installed on the source node.

I have following questions

Is it possible to change emulator during live migration? I try to to remove emulator under devices but looks like it does not help.

The migration API you've used (virDomainMigrateToURI3) supports additional parameters. One of the supported parameters is: VIR_MIGRATE_PARAM_DEST_XML: /** * VIR_MIGRATE_PARAM_DEST_XML: * * virDomainMigrate* params field: the new configuration to be used for the * domain on the destination host as VIR_TYPED_PARAM_STRING. The configuration * must include an identical set of virtual devices, to ensure a stable guest * ABI across migration. Only parameters related to host side configuration * can be changed in the XML. Hypervisors which support this field will forbid * migration if the provided XML would cause a change in the guest ABI. This * field cannot be used to rename the domain during migration (use * VIR_MIGRATE_PARAM_DEST_NAME field for that purpose). Domain name in the * destination XML must match the original domain name. * * Omitting this parameter keeps the original domain configuration. Using this * field with hypervisors that do not support changing domain configuration * during migration will result in a failure. * * Since: v1.1.0 */ So you fetch a migratable version of the XML (VIR_DOMAIN_XML_MIGRATABLE flag for the XML dumping API) and update the emulator path. Then feed it as the additional parameter