Define ioctl driver

ioctl based interfaces. ioctl () is the most common way for applications to interface with device drivers. It is flexible and easily extended by adding new commands and can be passed through character devices, block devices as well as sockets and other special file descriptors. However, it is also very easy to get ioctl command definitions wrong, and hard to fix them later without breaking existing .  · For more information, see Creating IOCTL Requests in Drivers. An I/O control code is a bit value that consists of several fields. The following figure illustrates the layout of I/O control codes. Use the system-supplied CTL_CODEmacro, which is defined in Wdm.h and Ntddk.h, to define new I/O control codes. DESCRIPTION top. The ioctl () system call manipulates the underlying device parameters of special files. In particular, many operating characteristics of character special files (e.g., terminals) may be controlled with ioctl () requests. The argument fd must be an open file descriptor.

The ioctl function is useful for implementing a device driver to set the configuration on the device. e.g. a printer that has configuration options to check and set the font family, font size etc. ioctl could be used to get the current font as well as set the font to a new one. A user application uses ioctl to send a code to a printer telling it to return the current font or to set the font to a new one. ioctl based interfaces. ioctl () is the most common way for applications to interface with device drivers. It is flexible and easily extended by adding new commands and can be passed through character devices, block devices as well as sockets and other special file descriptors. However, it is also very easy to get ioctl command definitions wrong, and hard to fix them later without breaking existing applications, so this documentation tries to help developers get it right. In computing, ioctl is a system call for device-specific input/output operations and other operations which cannot be expressed by regular system calls. It takes a parameter specifying a request code; the effect of a call depends completely on the request code. Request codes are often device-specific. For instance, a CD-ROM device driver which can instruct a physical device to eject a disc would provide an ioctl request code to do so. Device-independent request codes are sometimes used to give u.

Macros and defines used in specifying an ioctl() request are located in and semantics of ioctl() vary according to the device driver in. ioctl() Entry Point (Character Drivers) #define XXIOC (`x' << 8) /* `x' is a character representing */ /* device xx */ #define XX_GET_STATUS (XXIOC | 1). In this article. Other useful macros. When defining new IOCTLs, it is important to remember the following rules: If a new IOCTL will be.