在pci_qdev_realize这个函数位置设置断点。
bt栈如下：

Thread 1 "qemu-system-x86" hit Breakpoint 1, pci_qdev_realize (qdev=0x555556cb67f0, errp=0x7fffffffda40) at hw/pci/pci.c:2070
2070	{
(gdb) bt
#0  pci_qdev_realize (qdev=0x555556cb67f0, errp=0x7fffffffda40) at hw/pci/pci.c:2070
#1  0x0000555555a68aae in device_set_realized (obj=0x555556cb67f0, value=true, errp=0x7fffffffdc00) at hw/core/qdev.c:834
#2  0x0000555555c4ba4f in property_set_bool (obj=0x555556cb67f0, v=0x555556cbb020, name=0x555555f6aa11 "realized", opaque=0x555556c7fdb0,
    errp=0x7fffffffdc00) at qom/object.c:2079
#3  0x0000555555c49cb9 in object_property_set (obj=0x555556cb67f0, v=0x555556cbb020, name=0x555555f6aa11 "realized", errp=0x7fffffffdc00)
    at qom/object.c:1271
#4  0x0000555555c4cdc4 in object_property_set_qobject (obj=0x555556cb67f0, value=0x555556cbaf70, name=0x555555f6aa11 "realized", errp=0x7fffffffdc00)
    at qom/qom-qobject.c:26
#5  0x0000555555c49f97 in object_property_set_bool (obj=0x555556cb67f0, value=true, name=0x555555f6aa11 "realized", errp=0x7fffffffdc00)
    at qom/object.c:1337
#6  0x0000555555a67790 in qdev_init_nofail (dev=0x555556cb67f0) at hw/core/qdev.c:321
#7  0x0000555555b224c2 in pci_create_simple_multifunction (bus=0x555556c7f270, devfn=0, multifunction=false, name=0x555555f35b65 "i440FX")
    at hw/pci/pci.c:2131
#8  0x0000555555b22526 in pci_create_simple (bus=0x555556c7f270, devfn=0, name=0x555555f35b65 "i440FX") at hw/pci/pci.c:2142
#9  0x0000555555b199fe in i440fx_init (host_type=0x555555f35b6c "i440FX-pcihost", pci_type=0x555555f35b65 "i440FX", pi440fx_state=0x7fffffffdda8,
    piix3_devfn=0x7fffffffdd98, isa_bus=0x7fffffffdda0, pic=0x555556c7b5a0, address_space_mem=0x5555569b1a90, address_space_io=0x5555569b2510,
    ram_size=4294967296, below_4g_mem_size=3221225472, above_4g_mem_size=1073741824, pci_address_space=0x555556a60be0, ram_memory=0x555556a612d0)
    at hw/pci-host/piix.c:384
#10 0x0000555555937e59 in pc_init1 (machine=0x5555569ad800, host_type=0x555555f35b6c "i440FX-pcihost", pci_type=0x555555f35b65 "i440FX")
    at /root/code/qemu-4.1.0/hw/i386/pc_piix.c:201
#11 0x00005555559387e3 in pc_init_v4_1 (machine=0x5555569ad800) at /root/code/qemu-4.1.0/hw/i386/pc_piix.c:445
#12 0x0000555555a71a49 in machine_run_board_init (machine=0x5555569ad800) at hw/core/machine.c:1132
#13 0x00005555559fe083 in main (argc=25, argv=0x7fffffffe208, envp=0x7fffffffe2d8) at vl.c:4348