Open Source Summit Europe 2024

Direct Memory Access frees up the CPU for other important work, while devices read and write data in the background. This is as good as it sounds and most embedded systems make ample use of this; for good sound and otherwise. On the flipside, incorrectly configured DMA and the creeping memory corruption that results can decidedly be more unpleasant than the possible slow-down of using PIO. Ahmad's bootloader and kernel escapades have not been spared from the wrath of DMA masters. In this talk, he will share tales of his debugging campaigns and how tracking down memory corruption led him to learn, one bug at a time, more about the internals of Linux' and barebox' DMA API, ARM cache maintenance and the limitations of DMA controllers.