IOCTL_IEEE1394_API_REQUEST Adding and Opening Virtual Devices
in [Device Drivers]
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From: Freddie Witherden on 23 Sep 2010 18:12 Hello, I've been working on a WDF PnP driver which uses the IOCTL_IEEE1394_API_REQUEST with IEEE1394_API_ADD_VIRTUAL_DEVICE to add a virtual device. Assuming my driver is installed Windows will load it and it will create a device interface. My program then uses SetupDiEnumDeviceInterfaces and friends to find and open this handle. My problem is as follows. The first time a virtual device is created Windows takes a couple of seconds to delay-install the driver and create the interface. All subsequent uses of the virtual device after this are extremely quick. I want to know how my (library) code can work around this. Always sleeping for two seconds or so is firstly hacky, but also sub-optimal the second time my library is used (as the interface is created quickly). Moreover, after waking up there is no guarantee that a device interface will be created (such as if the driver is not installed on the system). How can my library do something along the lines of: "wait for an interface if the driver is installed" otherwise to exit fast? Repeatedly checking for new interfaces in a busy loop is also anything but ideal (and again, may be in vain). Finally, the virtual device created must be removed explicitly by user- space with the IEEE1394_API_REMOVE_VIRTUAL_DEVICE IOCTL. However, if a program using my library does not terminate correctly a virtual device (and hence my driver and an interface) is left dangling. Is there a means of cleaning up?
From: Maxim S. Shatskih on 24 Sep 2010 03:42 > How can my library do something along the lines of: "wait for an > interface if the driver is installed" otherwise to exit fast? You can subscribe to interface arrival notification with WM_DEVICECHANGE. > device (and hence my driver and an interface) is left dangling. Is > there a means of cleaning up? SetupDi APIs on the next app start. -- Maxim S. Shatskih Windows DDK MVP maxim(a)storagecraft.com http://www.storagecraft.com
From: Pavel A. on 24 Sep 2010 06:59
"Freddie Witherden" <freddie(a)witherden.org> wrote in message news:9688b562-091b-429a-b6e8-8d12f2c5785b(a)q9g2000vbd.googlegroups.com... > ................. > Finally, the virtual device created must be removed explicitly by user- > space with the IEEE1394_API_REMOVE_VIRTUAL_DEVICE IOCTL. However, if > a program using my library does not terminate correctly a virtual > device (and hence my driver and an interface) is left dangling. Is > there a means of cleaning up? What bad could happen if the device is left behind after your app exited? If nothing, you can just let it be; when the app runs again it will reuse the device. If you definitely must remove the device, make the driver detect that the app exited, for example, leave a pending ioctl. The driver will receive cleanup when the app exits. -- pa |