> Subject: Re: usb: a problem of using libusb for usb pass through > > 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 directory > > > > I 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? > > [ qemu uses one global libusb_context. libusb_device and > libusb_device_handle are allocated and released on open/close ] > > cheers, > Gerd >
Thanks for responding, Gerd. Would you have a plan to resolve it? -Gonglei
