my host system is gentoo amd64, guest system is Windows 7 amd64. the guest system can work, except it does not have sound. I start kvm with -soundhw ac97, QEMU_AUDIO_DRV='alsa', and after I get into the guest system, I can see a 'Multimedia Audio Controller' in the device manager. but Windows 7 cannot find the driver for it. I searched the network for a long time, and I cannot find a driver for Intel ac97 for Windows 7 amd64.
I also tried -soundhw sb16, es1370, none of them work.