OSDev.org

reading this thread pointed by The FAQ
why do i get an error like this:

timer.o(.text+0x5e): in function 'cpu_speed()':
: undefined reference to `__udivdi3'

when i try using 'unsigned long long start=0, ...' ? :/

the compiler doesn't know how to divide long longs natively: it needs a builtin function to do so...

To make this work, follow these steps :

1. Find your libgcc.a and copy it in a separate directory.
2. Execute commands :
ar x libgcc.a _udivdi3.o _umoddi3.o
ar r libm64.a _udivdi3.o _umoddi3.o
3. Then link libm64.a to your executable.

Works fine for me !