What is the role of ioctl in the OS kernel?

What is the role of ioctl in the OS kernel?

IOCTL is referred as Input and Output Control, which is used to talk with device drivers. IOCTL is a system call where system call is the programmatic way in which a computer program in user space requests a service from the kernel space of the operating system.

What does ioctl return?

A few ioctl() requests use the return value as an output parameter and return a nonnegative value on success. On error, -1 is returned, and errno is set to indicate the error.

Is ioctl a blocking call?

The IOCTL call has many functions; establishing blocking mode is only one of its functions. The value in COMMAND determines which function IOCTL will perform. The REQARG of 0 specifies non-blocking (a REQARG of 1 would request that socket S be set to blocking mode).

Is ioctl deprecated?

As I understand it, ioctls aren’t totally deprecated, but sysfs is preferred (?) I need to read/write sets of values simultaneously i.e. through one sysfs entry.

Is ioctl thread safe?

ioctl() is not one of them, so it IS thread-safe. However, ioctl() is a cancellation point, so the thread can be terminated once it reaches ioctl().

Is ioctl portable?

Direct calling of the ioctl system call is not portable on some architectures #8653.

How do you pronounce ioctl?

Like the Linux ioctl. Pronounced “i-oct-el”.

What is ioctl used for in Linux?

A common use of ioctl is to control hardware devices. For example, on Win32 systems, ioctl calls can communicate with USB devices, or they can discover drive-geometry information of the attached storage-devices.

What is the standard for ioctl 2?

No single standard. Arguments, returns, and semantics of ioctl (2) vary according to the device driver in question (the call is used as a catch-all for operations that don’t cleanly fit the Unix stream I/O model). See ioctl_list (2) for a list of many of the known ioctl () calls.

How do I call ioctl from a user application?

This is done by making the fops pointer “ unlocked_ioctl ” to point to “ etx_ioctl ” as shown below. Now we need to call the ioctl command from a user application. Just define the ioctl command like how we defined it in the driver.

Which statements should be removed from an ioctl?

Statements consisting only of original research should be removed. In computing, ioctl (an abbreviation of input/output control) is a system call for device-specific input/output operations and other operations which cannot be expressed by regular system calls.