➡ ➡ ➡ Link: Linux driver ioctl function
By using this site, you agree to the and. See 2 for a list of many of the known ioctl calls. The third argument is an untyped pointer to memory. Some of these facilities may not be foreseen by the kernel designer, and as a consequence linux driver ioctl function is difficult for a kernel to provide system calls for using the devices. Control operations are usually supported via the ioctl method. A pty is controlled and configured as if it were a hardware device, using ioctl calls. If there is such a thing in user-space, you need to search the implementation of ioctl in glibc. Browse other questions tagged or. Conforming to No single standard. The second argument is a device-dependent request code. As far as I can tell, it is unused in Linux kernel 3. The generally dispatches an ioctl call straight to the device driver, which can interpret the request number and data in whatever way required. See for details, and for techical background. An ioctl interface is a single system call by which userspace may communicate with device drivers. I am curious to know. In particular, if you ever want to get your driver included in upstream, you will have to have very good reasons why the ioctl interface is needed as opposed to using the normal character device features. So now int request is not just a macro, one is required to generate request code to be used by user application and device driver module to determine which configuration on device must be played with. Sebastopol, California: O'Reilly Media, Inc. By joining our community you will have the ability to post topics, receive our newsletter, use the advanced search, subscribe to threads and access many other special features. A Magic number - 8 bits 2. One sends a request code using ioctl from user application and then uses the request code in device linux driver ioctl function module to determine which action to perform. A sequence number - 8 bits 3. Browse other questions tagged or. Argument type typically 14 bitsif any. The system call vector is then used to find the desired kernel functikn for the request. The numberis completely up to you, if typeis unique to your driver. Conforming to No single standard. For example, on systems, ioctl calls can communicate with devices, or they can discover drive-geometry information of the attached storage-devices. If the typeis wrong in the ioctlthen the userspace will get an error of course. Conforming to No single standard. Sebastopol, California: O'Reilly Media, Inc.