When I am trying to insert a driver module in the kernel using 'insmod' command then it failed to insert.
Command Pattern:
insmod char_mod.ko
Error:
insmod: Failed to load char_mod.ko: Required key not available.
Solution:
Actually this issue happens only on UEFI system with enabled secure boot. So to resolve this issue you have to disable the secure boot on the UEFI system.
Unable to unregister_chrdev_region of kernel_module:Error
possible reasons:
1.) If you are using "NOD" as macro for no. of devices and save valued of macro in variables but passing MACRO
as argument instead of variable
2.) In MKDEV(major,minor) you have to take care that you must save the "dev_no" obtained from
MKDEV into new variable and pass that number into dev_add();
3.) Make sure in cleanup function that you try to remove device entry first by doing "dev_del" in a loop the kfree(dev) pointer and then unregister it.
One of the issue I am facing is my application is terminating, it simply terminates with no output , no errors , no warnings ; I have analysed that this is happening due to the node file absence , we should have the concern to the test file and also we have concern on mknod syntax in the test file to the appropriate step.. if node creation is successful with appropriate major no. then this error will overcome.
