Hello! I am writing a device driver module. I define some functions in the module, for example print_record(). I am doing something in the kvm, so I want to call print_record() in the file of kvm module, for example, I may call print_record() in file /arch/x86/kvm/x86.c to put something into my device driver module. Now comes the question. 1. Where should I put the codes of my device driver module? It's the first time I write the device driver. 2. After compiling my module, I encounter an error when I compile the kvm module. ERROR: "print_record" [arch/x86/kvm/kvm.ko] undefined! I use EXPORT_SYMBOL(print_record) in my module file. I use "extern" to declare print_record() and then call print_record() in file x86.c. To solve this problem, I have tried to copy the Module.symvers from my module folder to /arch/x86/kvm/. But it doesn't work. I have also tried to add *KBUILD_EXTRA_SYMBOLS *to the Makefile of kvm. It doesn't work either. I cat /proc/kallsyms and find that the type of symbol "print_record" is "t" ( local text). What should I do? How to call functions defined in my own module from kvm? Maybe there is something wrong in Makefiles? Any suggestion is appreciated! Thanks!