Hi, On 07/22/2013 02:58 PM, Gerd Hoffmann wrote:
On 07/16/13 10:45, Gonglei (Arei) wrote:Hi, Gerd My Qemu version is 1.5.1, and use libusb for usb pass through. I pass through a host usb device to the guest by bus number and physical port, when I unplug the usb device from the host, and plug in on the same physical port immediately, but the usb device don't show up in the guest. The qemu log show: libusb_release_interface: -4 [NO_DEVICE] libusbx: error [_get_usbfs_fd] libusbx couldn't open USB device /dev/bus/usb/002/004: No such file or directory libusbx: error [_get_usbfs_fd] libusbx couldn't open USB device /dev/bus/usb/002/004: No such file or directory libusbx: error [_get_usbfs_fd] libusbx couldn't open USB device /dev/bus/usb/002/004: No such file or directoryI find the reason is that the global libusb_context has recorded the usb devices' devnum, but when the host device was unplugged and plugged from the host, the devnum will change, finally cause the problem. Any ideas ? Thanks!Sounds like libusbx doesn't flush the cache on unplug even though it should. Hans?
This looks like qemu's host-libusb code is re-using the libusb_device handle, what it should do after seeing an unplug (ie ENODEV error), it should close both the handle, and free any devices it may have, then redo the libusb_get_device_list() and you should get a libusb_device with the new address. This is what the usb code in the spice-client does, and it has no problems with sc
[ qemu uses one global libusb_context. libusb_device and libusb_device_handle are allocated and released on open/close ]
That is fine, do you also free the device_list, and re-do the libusb_get_device_list() ? Regards, Hans
