This mode is primarily used to identify where exactly a flashing process fails, such as during the BROM (Boot ROM) stage or when a scatter file mismatch occurs.
It moves the "Trace Mode" from a wall of scrolling text (logcat/dmesg) into a diagnostic dashboard. Developers can see instantly if a flash is failing due to a bad cable, a corrupt partition table, or a hardware NAND failure.
Despite its power, Runtime Trace Mode has constraints. First, it requires physical access to the device and often to test points on the circuit board (e.g., TX/RX UART pads) or a specially modified USB cable. Second, the volume of data can be overwhelming—a trace of just the first two seconds of boot might generate tens of megabytes of raw logs. Third, enabling trace mode may slightly alter timing, potentially masking race conditions (the observer effect). Finally, using trace mode incorrectly—such as setting an invalid memory address watchpoint—can crash the preloader, turning a repairable device into a hard brick.