Working of character driver :see diagram & also see some queries of character driver.

The above diagram show how the character driver works in linux , user space to kernel space .

but when we implementing the driver there are many issues are find from inserting a driver to Removing the driver.

some are following:

1. why we use use sculldev because only cdev work as device of application ?
2. why we use container_of function if it,s only use of access the cdev address then what is its internal operations and how it work ?
3. we use kmalloc for providing the memory to sculldev if we want to print the value of sculldev which is garbage then that show errors : the variable is struct sculldev but we print value with %c ,there have no effect if we use type casting , what is solution ?
4. we use memset for fill the null values in sculldev how we can check sculldev filled with null ?
5. In cleanup function we use kfree ,that means free the memory of sculldev ,how we can check memory is totally free ,i mean how we can see that ?
6.  The return type of unregister_chrdev_region is void ,if we want check our device is unregistered sucessfully using printk statement.
7. what is motive of using cdev_del function because we already use rmmod,unregister function and after that cdev_del function ,what main purpose of this function ,we can see the output of this function.
8. what fundamentals of struct file and why we make the  struct file_operations because that is already included in header file which is fs.h and cdev.h .