Hardware register access is limited by the kernel config option CONFIG_IO_STRICT_DEVMEM. This means, userspace can't map the hardware register and thus nvme-cli is not able to read them. The access strict feature can be disabled by adding the kernel command line option 'iomem=relaxed' https://documentation.suse.com/smart/systems-management/html/task-modify-kernel-boot-parameter/index.html