Relationship Between/proc/devices and/dev

The device under/proc/devices/is generated by the driver, which can generate a major for mknod as the parameter. The devices under/dev/are added by mknod. You can use this device name to access the driver. The following script, scull_load, is part of the scull distribution. The user of a driver that is distributed in the form of a module can invoke such a script from the system'sRC. LocalFile or call it manually whenever the module is needed. #! /Bin/sh Module = "scull" Device = "scull" Mode = "664" # Invoke insmod with all arguments we got # And use a pathname, as newer modutils don't look in. By default /Sbin/insmod./$ module. Ko $ * | Exit 1 # Remove stale nodes Rm-F/dev/$ {Device} [0-3] Major =$ (awk "\\2 2 ==\" $ module \ "{print \ $1}"/proc/devices) Mknod/dev/$ {Device} 0 C $ major 0 Mknod/dev/$ {Device} 1 C $ major 1 Mknod/dev/$ {Device} 2 C $ major 2 Mknod/dev/$ {Device} 3 C $ major 3 # Give appropriate group/permissions, and change the group. # Not all distributions have staff, some have "Wheel" instead. Group = "staff" Grep-Q '^ staff:'/etc/group | group = "Wheel" Chgrp $ group/dev/$ {Device} [0-3] Chmod $ mode/dev/$ {Device} [0-3]

Please
Q: In Linux, what is the difference between the content in the/dev/directory and that in the/proc/file devices? When I did my experiment on the target board, I found that when I loaded the driver to the board
The devices file is changed while the/dev file is not changed at all. Shouldn't the/dev/file be the device contact? Why is the device contact set for the module, /dev/has not changed
?

Thank you for your help !!!

The devices in/proc/devices/are loaded to the kernel through insmod, which generates a major for mknod as the parameter.
/Dev/*. * is added by mknod. The format is mknod device1 C/B major minor, for example, mknod DR1 C 254 0. You can use this device name to access your driver.

 

 

 

Please
Q: In Linux, what is the difference between the content in the/dev/directory and that in the/proc/file devices? I'm
When I did an experiment on the board, I found that when I loaded the driver module to the Board, there were changes in the devices file, and there was no change at all under/dev, shouldn't it be a device connection under/dev/? Why?
When the module establishes a device contact, it does not change under/dev?
Thank you for your help !!!

 

The devices in/proc/devices/are loaded to the kernel through insmod, which generates a major for mknod as the parameter.
/Dev/*. * is added by mknod. The format is mknod device1 C/B major minor, for example, mknod DR1 C 254 0. You can use this device name to access your driver.

 

 

Device File, device number # ll-A/dev in each row can see the device file, device number (master, times)
For each hardware device, the system kernel has a device driver responsible for processing it. In UNIX, device files are used to represent hardware devices. Each device driver is abstracted as a device file. In this way, a consistent file interface is provided for applications, it facilitates communication between applications and operating systems.

Traditionally, all device files are stored in the/dev directory.

The devices in/proc/devices/are loaded to the kernel through insmod, which generates a major for mknod as the parameter.
/Dev/*. * is added by mknod. The format is mknod device1 C/B major minor, for example, mknod DR1 C 254 0. You can use this device name to access your driver.

Mknod-Make block or character special files
Mknod [Option]... name type [major minor]
Option is-M.
Name Customization
Type has B, c, and P
Master device number
Device No.

The master device number is defined by/usr/src/Linux/include/Linux/major. h. A doc device is defined as follows:
# Define igel_flash_major 62

Assume that there is a command mknod Doc B 62 0:
Here, Doc is the defined name, B refers to the block device, and 0 refers to the entire Doc. If 0 is changed to 1, 1 indicates the first partition of the doc. 2 is 2nd, and so on.