qemu monitor qom-get 获取device property

加上-monitor unix:qemu-monitor-socket,server,nowait启动qemu，从另一个shell进入monitor。info qom-tree可以看到所有的device以qom格式展示。通过qom-get可以得到对应设备的指定propoty。

info qom-tree大概长这个样子：

(qemu) info qom-tree
info qom-tree
/machine (virt-6.2-machine)
  /device-memory[0] (memory-region)
  /fw_cfg (fw_cfg_mem)
    /\x2from@etc\x2facpi\x2frsdp[0] (memory-region)
    /\x2from@etc\x2facpi\x2ftables[0] (memory-region)
    /\x2from@etc\x2ftable-loader[0] (memory-region)
    /fwcfg.ctl[0] (memory-region)
    /fwcfg.data[0] (memory-region)
    /fwcfg.dma[0] (memory-region)
  /mach-virt.ram[0] (memory-region)
  /nvdimm-acpi-io[0] (memory-region)
  /peripheral (container)
    /console0 (virtconsole)
    /nv0 (nvdimm)
。。。
  /peripheral-anon (container)
    /device[0] (virtio-rng-pci)
      /bus master container[0] (memory-region)
      /bus master[0] (memory-region)
      /virtio-backend (virtio-rng-device)
      /virtio-bus (virtio-pci-bus)
      /virtio-pci-common-virtio-rng[0] (memory-region)
      /virtio-pci-device-virtio-rng[0] (memory-region)
      /virtio-pci-isr-virtio-rng[0] (memory-region)
      /virtio-pci-notify-pio-virtio-rn

比如要得到virtio-rng-pci的device id，也就是bridge上的addr property，可以这样做：

(qemu) qom-get /machine/peripheral-anon/device[0] "addr"
qom-get /machine/peripheral-anon/device[0] "addr"
32
(qemu)

32并不是device id的值，它的单位是byte，addr/8应该是device id。可以通过lspci验证。