Comment 7 for bug 1853083

AIX 5.1 is quite a bit older than POWER8, so I don't think that it will run with this processor anymore. You could try "power5" or "970fx" as CPU (maybe even the "40p" machine instead of "pseries"), but I guess it won't make a big difference - the QEMU pseries machine has been written for later operating systems in mind, there was never a big effort to get older operating systems running with it.