synchronous abort on accessing unused I/O ports on aarch64 version: QEMU emulator version 5.2.0 (Debian 1:5.2+dfsg-6) command line: qemu-system-aarch64 \ -machine virt,virtualization=on,graphics=on,usb=on -cpu cortex-a57 -smp 2 -m 2G \ -device virtio-blk-device,drive=hd0 \ -drive if=none,format=raw,id=hd0,file=buildroot \ -kernel arch/arm64/boot/Image \ -nographic \ -device virtio-rng-pci \ -net user,host=10.0.2.10,hostfwd=tcp::10022-:22 -net nic,model=virtio-net-pci \ -append "root=/dev/vda earlyprintk=serial console=ttyAMA0 earlycon" I am observing "synchronous external abort" when kernel tries to access unused I/O ports (see below), while hardware/qemu should return 0xffffffff in this case. This is factored out of this LKML thread where Arnd describes it in more details: https://lore.kernel