Make aarch64 boot again and explain its limitations better.

Restore lkmc_min that was accidentaly removed.

Explain how to remove modules that fail to build.

run

@@ -63,6 +63,7 @@ case "$arch" in
     cmd="$qemu_common \
 -M pc \
 -append 'root=/dev/vda nopat $extra_append' \
+-device lkmc_pci_min \
 -device edu \
 -device virtio-net-pci,netdev=net0 \
 -drive file=${images_dir}/rootfs.ext2.qcow2,if=virtio,format=qcow2 \
@@ -94,7 +95,6 @@ $extra_flags \
 -append 'root=/dev/sda $extra_append' \
 -cpu cortex-a57 \
 -device virtio-net-device,netdev=net0 \
--drive file=${images_dir}/rootfs.cpio,if=scsi,format=raw \
 -kernel ${images_dir}/Image \
 -nographic \
 -serial stdio \