To use Linux in the Power Virtual Service at IBM Cloud you must bring your own image if you do not want to use IBMi, AIX or SUSE. This Linux image should be a .ova file. The OVA file is saved in the Open Virtualization Format (OVF), which is a standard format used to package and distribute software that is run in virtual machines. OVA files are simply an OVF directory saved in a single archive using .TAR packaging for distribution purposes. If you do not have access to PowerVC instance to create your own .ova image, the following steps will help you on creating one!
Step 0: request access to Minicloud to get your Power virtual machine up and running.
Step 1: once the access is approved and you have your CentOS8 VM available, configure it as a build environment
dnf update -y; dnf install -y git wget qemu-img.ppc64le python3
Step 2: clone the repository where the generator script is located
git clone https://github.com/ocp-power-automation/infra.git; cd ./infra/scripts/images
Step 3: download the CentOS8 qcow image that will be used as an entry point for the new image build
Step 4: build the new .ova image setting the parameters according your needs
sudo ./convert_qcow2_ova.py -u FILE -s ZISE -n NAME -d DISTRO -O PASSWORD
sudo ./convert_qcow2_ova.py -u ./CentOS-8-GenericCloud-8.2.2004-20200611.2.ppc64le.qcow2 -s 120 -n centos82-openpowerlab-09182020 -d centos -O passw0rd
Step 5: upload this new .ova to a new bucket at IBM Cloud, see this and this.
Step 6: Create a new boot image in your already existing PowerVS instance, or create a new PowerVS service and create a new boot image.
Step 7: Deploy your new CentOS8 image and access the VM.
Step 8: You can get images from here if you do not want to build it.