
Some devices seem to choke on receiving a USB_REQ_GET_CONFIGURATION ctrl msg (witnessed with a digital picture frame usb id 1908:1320). When usb_fs_type == USB_FS_SYS, the active configuration can be read directly from sysfs, which allows using this device through qemu's usb redirection. More in general it seems a good idea to not send needless control msg's to devices, esp. as the code in question is called every time a set_interface is done. Which happens multiple times during virtual machine startup, and when device drivers are activating the usb device. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Read the documentation in qemu-doc.html. Fabrice Bellard.
Description
Languages
C
90.3%
Dylan
2.5%
Python
2.1%
C++
2%
Shell
1.7%
Other
1.4%