How to read cpu frequency?

[gulweb]

F_CPU is a literal, defined in boards.txt. It could probably be calculated from the menu if there was an external clock entry
since all the dividers are setup correctly, making running @ 240 Mhz OK.

I cannot find any reference to SystemCoreClock, which should be a variable set when clock is configured or reconfigured.

Right now my board always reports a speed of 80 Mhz, and other variables controlled by F_CPU scale on that.
A manual edit of boards.txt of course fixes it.