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Questions tagged [ioctl]

ioctl (Input Output ConTroL) is a system call for device-specific I/O operations and other operations which cannot be expressed by regular system calls and it provides an interface through which an application can communicate directly with a device driver(or any other global kernel space variables). Applications can use the standard control codes or device-specific control codes to perform direct input and output operations.

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IOCTL call not working with driver

I wrote a IOCTL driver and a corresponding ioctl app with a header file containing commands. #include #include #include #include #include #include #include…
pointer accurate
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Why the number of system calls is very limited?

I was playing with ioctl and this question occurred to me. Background I was told that the primary motivation for system calls is that the number of interrupt handlers allowed is very limited. So many OSes implement the abstraction of system calls…
wlnirvana
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Handling interrupt in character device

I am trying to correctly register interrupt in kernel for user interface. Surprisingly, I did not find many examples in kernel for that. irq handler static irqreturn_t irq_handler(int irq, void *dev_id) { struct el_irq_dev *el_irq =…
ransh
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DeviceIoControl is totally not working, SystemBuffer empty on return

i have got an IOCTL being sendt down to my driver with a structure, the structure is passed successfully, then my driver does its magic, but when its done it should return a simple unsigned _int64 which is 8 bytes long, i set the IRP's…
Paze
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Access a raw disk in Random Access mode C++

Now, I'm already familiar with the DeviceIoControl (ioctl) process and can read from a disk sequentially, 512 bytes at a time. I create a handle from the list of \.\PhysicalDrive(s) and identify it via IOCTL_STORAGE_QUERY_PROPERTY command. Then…
Doğukan Tunç
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Can manually set up Ethernet but not WiFi communication using C program

I have written a C program that can set an IP address and a subnet mask of the user's choice for any available network interface. I am able to establish communication between two computers connected to each other by an ethernet cable by simply using…
Kenneth Goveas
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Issues printing a MAC address

A MAC address is parsed into an array of bytes (macaddr). The bytes are printed with printf() one after another. The bytes are supposed to look as pairs of hexadecimal characters. But some of them are padded with f characters. For example, for…
hwisang
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C++ - Send IOCTL command to WBF to get sensor attributes on Windows

I'm trying to understand how I can retrieve the WINBIO_SENSOR_ATTRIBUTES buffer by using WBF APIs. I found this link: https://msdn.microsoft.com/en-us/library/windows/hardware/ff536431 It mentions about sending IOCTL command, however, I'm not able…
pree
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How to write Linux driver IOCTL routine?

I have a Input output card which I am connecting to My PC through PCIe Interface. I have written a driver for linux to access the device this is IOCTL routine. static int _ioctl(struct inode *inode, struct file *file, …
Karthik KP
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KMDF IOCTL communication with nonpnp driver?

I am trying to write a windows non-pnp kernel mode software driver which should communicate bidirectional with my user mode app (user sends request and driver responds). The problem is that I can't find examples or documentations - the msdn sample…
h4x0r
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ioctl() call resets file descriptor to 0

Consider the following code: file_fd = open(device, O_RDWR); if (file_fd < 0) { perror("open"); return -1; } printf("File descriptor: %d\n", file_fd); uint32_t DskSize; if (ioctl(file_fd, BLKGETSIZE, &DskSize) < 0) { …
Gala
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VIDIOC_REQBUFS Error 12 when opening multiple v4l2 sources

I'm using an 8-channel PCI-based framegrabber on Nvidia TX1 dev kit. I'm using this driver along with it. I can play up to 3/4 v4l2 camera feeds comfortably using mplayer, streamer or VLC but I always get a memory allocation error when I start…
alasin
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WDF Internal IOCTL Not Returning Output

I’m currently writing a driver that exposes virtual COM ports. In the driver, I send an internal IOCTL from the port FDO down the stack, which is handled from the PDO IO queue. For some reason, the output data is not written to the provided output…
GregoryComer
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IOCTL: only work with parameter 0 in the switch-case

I am creating a driver for a embeeded system. I am using IOCTL function. The device is register correctly and the open and write functions work as expected but IOCTL doesn't. When I call IOCTL from user space with parameter 0 the my_ioctl function…
manolo tunez
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Kernel modules and major numbers

I have been reading up on drivers implemented as kernel modules and am confused about the CMD argument to the system call. It seems that the CMD argument to the system call encodes amongst other information, the major number of the device. Why is…
user277465
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