Most kernel code and drivers in particular are written for multiple architectures. They need to respect an abstract memory model to run on all architectures. x86 is the most relaxed of the supported architectures. You can get away with violations of that model that cause subtle bugs on other architectures. Yet x86 is the architecture most people test on. This talk is about which rules apply to ARM. It shows what can go wrong if the rules are not obeyed and how the memory model is correctly respected in drivers. The talk has two main sections. In the first section DMA is covered. In the second section SMP is covered.