> I read pci code in qemu about i440fx, pci.c and so on. I think if guest > os whose mainboard is based on x86, it will use IO instructions to > access PCI configuration space.If not use passthrough, qemu should > emulate these operations.I find a function called kvm_handle_io who will ^^^^^^^^^^^^^
Looks suspicious. Prefix kvm mean passthrough, I guess. > emulate ioport write/read, I have traced this function, but I haven't found > it has > any relationship with pci read/write configuration space functions like > i440fx_write_config and piix3_write_config.So how does it emulate pci > configuration space access when not use passthrough? `grep -r i440fx_write_config *` show you that you should take a look on hw/piix_pci.c. Besides, setting breakpoint at i440fx_write_config also show you how it get called. HTH, chenwj -- Wei-Ren Chen (陳韋任) Computer Systems Lab, Institute of Information Science, Academia Sinica, Taiwan (R.O.C.) Tel:886-2-2788-3799 #1667 Homepage: http://people.cs.nctu.edu.tw/~chenwj