yes interesting Christian , the only worst thing of Qemu is the emulated jit instruction very / really slow compared some others solutions that was made in the past for emulate alien architectures on the not X86 machine .
Example : on My G5 i have Windows 7 on Virtual Pc and it perform pro-quake 320x240 in a window at 88 fps ... on Qemu i have 7-10 fps.
AmigaOne Xe 933 mhz Radeon 9000pro Samsung 840 SSD
Pegasos2 1266mhz Radeon 9800pro Verbatib Sata3 SSD
Sam 460ex Lite 2gb Ram , Radeon 6670,Toshiba 500gb Sata/HDD
Amiga Cd32 / Amiga 600 / Amiga 500 / Amiga CDtv/ Amiga 4000 / Amiga 1200 /Amiga 2000 and many many many z3 Boards
As you certainly know, Mac OS X can't boot on QEMU with "PR" KVM enabled. But ... the new QEMU by Alexander Graf's git with kernel 3.17 RC 2 can boot Mac OS X in the single-user mode in QEMU with "PR" KVM enabled.
I have good news. I have created an ISO from my Mac OS X 10.4 Tiger DVD (retail box version). And then I have installed it with PearPC on a HD image. Mac OS X Tiger starts without any problems on QEMU with KVM-PR enabled from this HD image on my A1-X1000.
Screenshots:
The performance is higher than without KVM-PR. But it could be a little faster for productive work. I think Mac OS X Tiger works very fast on a POWER8 system. My problem was Jaguar. It can't start with KVM-PR enabled.