Automotive Linux Summit & Open Source Summit Japan 2018

This talk is about findings which originated from an issue in the I2C subsystem but then became more widespread. The question was if externaly allocated message buffers for the I2C subsystem need to be DMA safe. That gained importance and needed a proper solution.

While working on this, buffer handling in other subsystems was evaluated regarding DMA safety. It turned out that some, including I2C, work rather by coincidence or, at least, on assumptions which are likely to be true, but not always. And those assumptions might even be less likely true in the future, given some structural changes virtualization brings.

Learn that a check if buffers are DMA capable is surprisingly not an easy task. And find out which solutions exist as of today. With safety being a main interest for automotive, more eyes are needed for this problem.