Kernel Debugging: Difference between revisions

In places where a full print or logging function is not feasible (such as when trying to isolate a single erroneous assembly language instruction), you can create a kind of 'pseudo-breakpoint' by inserting a HLT instruction into the code. These can be used to perform a binary space isolation (often referred to as a 'binary chop') through the code. The idea is to place the halt instruction at a point roughly halfway through the part of the code suspected to be at fault; if the CPU halts before the error occurs, then you know that the error is after the breakpoint, otherwise, it must be in the code before breackpointbreakpoint. Repeat this procedure until the error is isolated. Unfortunately, this only works if the result of the error can be differentiated from the halt instruction itself, and it does little in the case of a problem occurring more than one repetition into loop, such as an array overrun.