[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] usb: a problem of using libusb for usb pass through
From: |
Gerd Hoffmann |
Subject: |
Re: [Qemu-devel] usb: a problem of using libusb for usb pass through |
Date: |
Mon, 22 Jul 2013 14:58:59 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130621 Thunderbird/17.0.7 |
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