discrete device

Using asynchronous notifications in device drivers can make access to the device accessible to the application by the driver when it is accessible. Therefore, applications that use nonblocking I/O do not need to poll the device for access, and blocking access can be superseded by asynchronous notifications like "break". Asynchronous notifications are similar to t

First, Mknod: Set the device codeIn Linux, all devices are represented by files, and the files are judged by major and minor values.Major is the main device code, minor is the device code (need to query), the example is as follows:/dev/hda---------major:3------minor:0~63/DEV/HDB----------major:3------minor:64~127/DEV/SDA----------major:8------minor:0~15...Command

A Linux device model can be better understood through various stages of a device's life cycle in the kernel. I will analyze the source code of ldquo and sculld to understand the integration of each link in the Linux device model. The integration of the (PCI Bus) in ldd3 serves as a reference, because embedded Linux uses less PCI bus. First, you must familiarize yourself with the source code of ldquo and scu

Main device number and secondary device number Those names are called special files, device files, or nodes that are simply called file system trees, and they are usually located in the/dev directory Typically, the main device number identifies the driver that corresponds to the

In this walkthrough, you will use Visual Basic or Visual C #Generate a simple windows form applicationProgram,Then run the application on the Pocket PC simulation program.This walkthrough demonstrates the main differences between desktop programming and device programming,That is, you must specify the target device.During this drill, the device is a built-in simulation program of the Pocket PC 2003.--------

functions when interacting with the memory management subsystem.3. File systemEach Unix object can be viewed as a file.The kernel constructs a structured file system on hardware that has no structure.Linux supports a variety of file system types, essentially different ways of organizing data on physical media.4. Device ControlAlmost every system operation will eventually be mapped to a physical device. In

0. Preface　　Graduate life all are on the right track, I also started a new study, because really do not want to make storage, so decided to study with the elder brother device driver, read the book two weeks, finally a little clue, began to record it!1. Preparatory workA) View the kernel versionUname-rb) Install kernel source tree (http://www.cnblogs.com/Jezze/archive/2011/12/23/2299871.html)　　Download the source code in www.linux.org, here is the. xz

Devices in the system that can randomly (and do not need to sequentially) access fixed-size data slices (chunks) are called block devices, which are called blocks. The most common block devices are hard disks, and in addition, there are many other block devices, such as floppy drives, CD-ROM drives, flash memory, and so on. Note that they are all used in a way that installs the file system-this is also the general way to access the block device.Another basic

Device object (device_object) --------------- main Member I. device object (device_object) Kd> dt _ device_objectNtdll! _ Device_object+ 0x000 type: int2b+ 0x002 size: uint2b+ 0x004 referencecount: int4b+ 0x008 driverobject: ptr32 _ driver_object; driver object of the device+ 0x00c nextdevice: ptr32 _ device_object; points to the next

The tty core code tty_io.c contains the following lines of code: /* * Ok, now we can initialize the rest of the tty devices and can count * on memory allocations, interrupts etc.. */static int __init tty_init(void){ cdev_init(tty_cdev, tty_fops); if (cdev_add(tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) || register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") Several system-level terminal devices are created here. They are not real physical devices. Each of them creates these

The biggest feature of Linux devices is that device operations are like file operations. In the application layer, a hardware device is just a device file. Applications can operate hardware devices like operating files, such as open (), close (), read (), and write. Below is a simple implementation of the character device