Implicit declaration of a function 'clock'

Question

Hello every one I am writing a kernel module and want to find the clock cycles of a particular function. I have included the library #include </linux/time.h> then declared

clock_t c0;

c0 = clock();

but I am getting the error

implicit declaration of a function clock

Can any one help me solve this problem?

I am using gcc on Linux.

Answer 1

The function clock is in libc. By definition, when you're developing for the kernel you don't have access to libc functions (look up "freestanding environment").