Open Source Summit + Embedded Linux Conference North America 2026

Transitioning from bare-metal firmware development to Linux kernel development presents unique challenges, particularly in debugging methodologies. Traditional approaches such as halting execution via JTAG alone may not straightforwardly work for embedded Linux.

In this presentation we talk about challenges I faced and techniques I came across to debug Linux MMC block device drivers interactively using tools such as T32/GDB debuggers on embedded systems. This talk briefly covers MMC driver and block layer interactions and key golden breakpoints to use for MMC bus driver debugging. I will also discuss tools and techniques to take full control of eMMC block drivers, generating block IO requests as needed, setting up triggers and probing signals on an oscilloscope for detailed waveform level debugging.

key topics: Embedded Linux setup for interactive debug (single CPU, KASLR, WDT, ramfs, RCU, softlocks), strategic SDHCI breakpoints, GPIO-triggered oscilloscope capture signals, handling filesystem mounts; leveraging mmc_test module for generating controlled transactions for debug.