So there is no option in the compiler to set the clock frequency of the processor....How will that be handled? Do i need to edit the Makefile?
Why would the compiler need to know the target CPU clock frequency? It has no use for it. On the other hand, you need to know it to calculate baudrates, timer frequencies and so on.
"It has no use for it."
Absolutely!
However, the Simulator needs to know it in order to relate cycle times to "real" times. And the debugger?
That's why uVision has an option to set it - but, as you say, it's nothing to do with the Compiler.
http://www.keil.com/support/man/docs/uv3/uv3_dg_targkarm.htm