Smartphone Flash Tool -runtime Trace Mode- Apr 2026

Add a new USB class (0xFF, subclass 0x02) for trace data. In brom.cpp :

RTM default recommendation: Fallback UART + USB bulk when available. | Mode | Data Generated | Bandwidth Requirement | Use Case | |-------|----------------|------------------------|------------| | PC-Only | 4 bytes per instruction | ~200 KB/s (at 100 MHz, 1:1000 sampling) | Locating infinite loops | | PC + Load/Store Address | 12–16 bytes per memory op | ~5 MB/s | Detecting wild pointers | | Register Delta | 2–8 bytes per taken branch | ~1 MB/s | Tracking boot state machine | | Full Execution Trace | All of above | ~50 MB/s (impractical for UART) | Post-mortem analysis with USB | smartphone flash tool -runtime trace mode-

Document Version: 1.0 Subject Area: Embedded Systems Debugging, Mobile Device Firmware Tooling Target Audience: Firmware Engineers, Security Researchers, Android OEM Developers 1. Abstract Traditional smartphone flash tools (e.g., SP Flash Tool, Qualcomm QFIL, Samsung Odin) operate in a black-box programming mode . They send pre-built firmware images (bootloader, kernel, system) to the device’s memory partitions with minimal runtime feedback. This paper introduces Runtime Trace Mode (RTM) — an extension to conventional flashing tools that enables real-time instruction execution tracing, memory access logging, and register state streaming from the device’s boot ROM and bootloader during the flashing process. RTM transforms the flash tool from a simple programmer into a low-level interactive debugger, crucial for diagnosing boot failures, verifying secure boot chains, and analyzing proprietary bootrom exploits. 2. Introduction Smartphone boot sequences involve multiple stages: BootROM → Preloader → Little Kernel (LK) / U-Boot → Kernel. A single corrupted partition or misconfigured security fuse often results in a dead device (hard brick). Conventional flash tools provide no insight into why the device halts. They only succeed or fail with opaque error codes (e.g., STATUS_BROM_CMD_SEND_DA_FAIL ). Add a new USB class (0xFF, subclass 0x02) for trace data

Patch offsets: SPFlashTool.exe @ 0x2A3F4 – enable hidden menu, then Ctrl+Shift+T for trace console. Abstract Traditional smartphone flash tools (e