When should I write a Linux kernel module?

Question

Some people want to move code from user space to kernel space in Linux for some reason. A lot of times the reason seems to be that the code should have particularly high priorit

Answer 1

Code running in the kernel accesses memory, peripherals, system functions in ways that are different from userspace code and thus has the ability to be more efficient. Not to mention the reduced security restrictions for kernel code. However, all this usually comes at a cost, such as increasing the possibility of opening the kernel up to security threats, locking up the OS, complicating the debugging, and so forth.