1. A system comprising: a marker from a plurality of markers carried by a respective one of a plurality of code-blocks; a processor configured to detect a change in the marker in an instruction stream, and configured to identify whether to notify an operating system when there is a change in the marker; and a compiler/interpreter to determine the marker for each code-block and tag the code-block with the marker; wherein the plurality of code-blocks comprise an instruction set to be executed on the processor; wherein each of the plurality of code-blocks comprises at least one of a plurality of characteristics that define how the processor uses each of the plurality of code-blocks; wherein the processor uses each of the markers to differentiate between each of the plurality of code-blocks and tracks control transfers between any of the plurality of code-blocks.