Driver reading configuration file

I don't know about files, but you can send all the values you want to a kernel module at load time by using module parameters. Module parameters take the format "parameter=value" eg: insmod mymodule iobase=0x300 irq=3 mystring="this is a cool string"

Would iobase and mystring be global variables in the module that could read as usual? Would they need to be declared in the module?

I am not sure if that will work. We want to put the variable into a configuration file that both the application and the driver that is closely related to it can read.

If you want to open a file and read the contents from within your kernel module, you are to be discouraged. It's possible but frowned upon, and the way mentioned to you is simpler and better. To recap, the parameters for the module are passed via the module loader, which is either explicitly invoked as part of startup scripts for your program, or pulled in from the configuration files by the automatic module loading facility such as devfs.

There is one other way: load or statically include your module, and then have your application open the corresponding device, and pass the parameter via a special ioctl() syscall.

Yes. The module parameters will have to be normal global variables. Yes they will have to be declared in the module and will have to be associated with a module parameter with the macro "module_param( iobase, int, 0)". If you really want it to use the same config file, I suggest you use the IOCTL method that Przemek has described.

I wrote a script that reads the variable's value in the config file and then passed it to the driver via insmod. This works fine. Thanks for the recommendations.