I am using IOP341 for storage product research. To improve the performance, I have read some documents about IOP341 (such as, 3rd Generation Intel XScale® Microarchitecture Developer’s Manual.pdf). These documents all say that the IOP341 support cache coherence by hardware, but the issued linux kernels do not support this function, i.e. arch_is_coherent() in Linux kernel is set as 0 initially. However, the system can not work normally when I write it as 1. The problem should be caused by the DMA because of the cache coherence. All the devices such as network, disk working with DMA can not work normally any more. If I want to fix the bug/problem, what should I do? Who has ideas or suggestions? Thanks!