"I connected my mobile phone to the USB and entered '-device_add: invalid option'. I used the following command: root@localhost:/home/xp# qemu-system-x86_64 -hda /win7.qcow2 -display vnc=127.0.0.1:0 -monitor stdio -machine pc,usb=on Then I checked the console with 'info usbhost' and it showed that the device could be connected. However, after I unplugged and plugged it back in, entering 'info usbhost' had no response. What should I do? The device is a Linux ARM64."
