Nigel, looking at https://www.freebsd.org/platforms/ppc.html it seems like FreeBSD does not support the pseries machines yet, only some flavours of PowerMac machines. So you should either use the "qemu-system-ppc" binary (without the "64" suffix), or you've got to specify one of the Mac machines, i.e. either "-M g3beige" or "-M mac99".
Nigel, looking at https:/ /www.freebsd. org/platforms/ ppc.html it seems like FreeBSD does not support the pseries machines yet, only some flavours of PowerMac machines. So you should either use the "qemu-system-ppc" binary (without the "64" suffix), or you've got to specify one of the Mac machines, i.e. either "-M g3beige" or "-M mac99".