Running in emulation mode (TCG)

Sometimes it’s useful to run Avocado-vt in emulation mode (eg. when checking PR about different architecture, or to debug certain feature while executing the test). As this is not default, extra arguments are usually required.

Shared for all architectures is that you need the image. We supply JeOS for most of the architectures, so you should be able to get it via:

$ avocado vt-bootstrap --vt-guest-os JeOS.$VERSION.$ARCH


  • VERSION is JeOS version (when writing this document it was 27)
  • ARCH is the desired architecture (eg. aarch64)

Or you can run any of the unattended_install tests with --vt-guest-os of your choice (very slow).

When running the tests, on top of the usual arguments, you usually need to specify:

  • --vt-qemu-bin - path to binary that supports expected architecture (eg. /usr/local/bin/qemu-system-aarch64)
  • --vt-qemu-dst-bin - for migration tests you need also to specify the destination qemu binary (otherwise default one is used)
  • enable_kvm=no - to disable KVM (if necessary)


Some test require additional dependencies and are marked as no JeOS (another group is marked as only RHEL) but it might be useful for debugging purposes to use them with JeOS. You can do that by symlinking the $avocado-vt-data/images/jeos-$version-$arch.qcow2 to $avocado-vt-data/images/rhel${version}devel-$arch.qcow2 and using the boot test with --vt-guest-os RHEL.$version. To add extra packages use ctrl+Z when it’s about to ssh in. Then you can ssh to that guest from your machine, run dnf install ... to install the extra packages (gcc suffices for most test), shut the machine down, backup it to $name.backup and resume the boot test by ctrl+Z. Obviously the test will fail, refreshes the image from $name.backup but since then you have slightly fattier JeOS symlinked to RHEL capable of running some extended tests without the need to run full installation in TCG mode. Beware, vt-bootstrap might overwrite the .backup from archive.


ARM always requires cpu_model as well as machine_type. To get list of available models you can run qemu-system-aarch64 -cpu help -M virt (note: not all listed cpus are bootable). By default Avocado-vt uses -machine $machine_type,gic-version=host to use host’s GIC version, but this is not possible to evaluate in TCG (especially without GIC on x86) so one needs to either pick a fixed version or simply use qemu default by cleaning the machine_type_extra_params. Complete example would be:

$ avocado vt-bootstrap --vt-guest-os JeOS.27.aarch64
$ avocado --show all run --vt-extra-params enable_kvm=no cpu_model=cortex-a57 \
    machine_type_extra_params='' --vt-machine-type aarch64 --vt-arch arm64-pci \
    --vt-qemu-bin /usr/local/bin/qemu-system-aarch64 -- boot


PowerPC can use either BE or LE instructions, but from qemu point of view nothing changes. Still for Avocado-vt you either have to specify --vt-arch ppc64 or --vt-arch ppc64le to choose the right distribution image (both were available as JeOS when writing this document). Apart from this no additional tweaks are necessary:

$ avocado vt-bootstrap --vt-guest-os JeOS.27.ppc64
$ avocado --show all run --vt-extra-params enable_kvm=no --vt-arch ppc64 \
    --vt-machine-type pseries --vt-qemu-bin /usr/local/bin/qemu-system-ppc64 -- boot

$ avocado vt-bootstrap --vt-guest-os JeOS.27.ppc64le
$ avocado --show all run --vt-extra-params enable_kvm=no --vt-arch ppc64le \
    --vt-machine-type pseries --vt-qemu-bin /usr/local/bin/qemu-system-ppc64 -- boot


For KVM execution Avocado-vt uses -cpu host on s390x, which is not possible without KVM. To execute in TCG mode you need to replace it with either a supported CPU type or simply leave it blank:

$ avocado vt-bootstrap --vt-guest-os JeOS.27.s390x
$ avocado --show all run --vt-extra-params enable_kvm=no cpu_model='' --vt-arch s390x \
    --vt-machine-type s390-virtio --vt-qemu-bin /usr/local/bin/qemu-system-s390x -- boot


When writing this document, riscv64 was not available as JeOS and even Fedora support was not straight forward. See `riscv64_setup`_ for setup instructions. Apart from the setup running riscv64 does not require any additional arguments:

$ avocado run --vt-machine-type riscv64-mmio --vt-arch riscv64 \
    --vt-extra-params enable_kvm=no --vt-guest-os Fedora.28 -- boot