Driver Module Loading

Enter the generated directory. insmod./Hello. Ko loads the driver.

Module size used
Hello 9472 0
Nls_iso8859_1 12032 0
Nls_cp437 13696 0
Vfat 18816 0
Fat 58272 1 vfat
Usb_storage 82880 0
Isofs 39844 1

Lsmod lists all drivers. Lsmod reads and analyzes the/proc/modules file.

CAT/proc/modules

Nls_iso8859_1 12032 0-live 0xe1bc6000
Nls_cp437 13696 0-live 0xe1bba000
Vfat 18816 0-live 0xe1bad000
Fat 58272 1 vfat, live 0xe1b50000
Information about loaded modules in the kernel exists in the SYS/Module Directory.

Go to the/sys/module directory tree-a to get the directory tree:

Usb_storage
| -- Drivers
| '-- USB: USB-storage->.../bus/USB/Drivers/USB-storage
| -- Holders
| -- Initstate
| -- Notes
| '--. Note. GNU. Build-ID
| -- Parameters
| -- Delay_use
| -- Option_zero_cd
| '-- Swi_tru_install
| -- Refcnt
| -- Sections
| --. BSS
| --. Data
| --. Exit. Text
| --. GNU. linkonce. this_module
| --. Init. Text
| --. Note. GNU. Build-ID
| --. Parainstructions
| --. Rodata
| --. Rodata. str1.1
| --. Rodata. str1.4
| --. Smp_locks
| --. Strtab
| --. Symtab
| --. Text
| -- _ Bug_table
| '-- _ Param
| '-- Srcversion

L/Drivers/Hello # modinfo hello. Ko
Filename: Hello. Ko
Alias: a simplest Module
Description: a simple hello World module
License: Dual BSD/GPL
Author: Barry song <21cnbao@gmail.com>
Srcversion: 3fe9b0fbafdd565399b9c05
Depends:
Vermagic: 2.6.28-11-generic SMP mod_unload modversions 586

Modprobe is used to mount a new module and a module on which the new module depends modprobe. Our common function is to mount a module. When a kernel module is mounted, the modules on which this module depends are also mounted; this is different from the insmod mounting module. Of course, modprobe also provides a list of all kernel modules, as well as the function of removing modules. Next we will give an example to illustrate our common functions and parameters;

Modprobe-codprobe-C can view the modules configuration file, such as the module alias;

Modprobe-L is used to list all modules in the kernel, including mounted and unmounted modules,

Read File:/lib/modules/'uname-R'/modules. Dep

We can check the required modules and mount them as needed;

[Root @ localhostbeinan] # modprobe Module name Note: mount a module;
[Root @ localhostbeinan] # modprobe-R module name Note: remove the loaded module, which has the same function as rmmod;

Ifneq ($ (kernelrelease),) # kernelrelease is not empty. It is valid when the second entry is made.
OBJ-M: = Hello. o
Hello-objs: = Main. o add. o
Else
Kdir: =/lib/modules/2.6.18-53/build

ALL:
Make-C $ (kdir) M = $ (PWD) Modules # enter the kdir directory and execute make modules
Clean:
Rm-f *. Ko *. o

Endif

Kernel module parameters: these parameters are included after the insmode installation module is executed.
Module_param (name, type, Perm) parameter name, parameter type, access permission
Perm common value: s_irugo: any user has read permission for this parameter in/sys/module.
S_iwusr: the root user has read permission on the parameter displayed in/sys/module.
Int A = 3; // initialize the default value.
Module_param (A, Int, s_iwuser );
This parameter can be used in the kernel.
The function implemented in module A must be exported using export_symbol before it can be called by other modules. The exported list is in the proc/kallbyms file.
Export_symbol (function );
The difference between the kernel module and the application is that after the kernel is installed, it will always reside in the memory. As a service, it will serve a certain request in the future until it is uninstalled.

The function is called.
Printk (kern_emer, "emergc"); // contains the print level