It depends what you want to achieve. In any aspects, polling is not a good idea for driver anyway. You may want to send a message from driver when something in driver occurs, and setup your application to listen that message. After user-mode application receive the message, then you can call your function in the user space and/or use IOCTL for what you really want to do. On 4/9/07, AsHwAtH <itsmeash@xxxxxxxxx> wrote:
Ok, Thank you for the suggestion. But how are callbacks really implemented then? If I keep calling DeviceIOControl from my application(like polling), it drains CPU usage. On 4/9/07, Eugene Muzychenko <emuzychenko@xxxxxxxxx> wrote: > Hello AsHwAtH, > > > From my application I am passing the address of the User defined function to > > the driver through my own IOCTL call. > > I store this address in the driver as a function pointer and call it when a > > particular condition is met inside the MSVAD. > > Before trying to develop (and even modify) a kernel-mode driver, you > must clearly understand the differences between user and kernel > execution modes, address space, thread contexts etc. Your attempt to > directly call a user-mode function from the kernel-mode driver means > that you have almost no such knowledge. In this situation, your work > will be very inefficient, resulting many incorrect solutions. > > Your driver could inject some code into a requesting > process, create an auxiliary thread that will watch for some event > signaled by the driver and call a specified function. But it will be > very complex for you to implement. So a simplest way is to create a > thread from your application and not to pass function address to the > driver. > > Regards, > Eugene > > ****************** > > WDMAUDIODEV addresses: > Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx > Subscribe: mailto: wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe > Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe > Moderator: mailto: wdmaudiodev-moderators@xxxxxxxxxxxxx > > URL to WDMAUDIODEV page: > http://www.wdmaudiodev.com/ > >
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