From: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> Date: Tue, 22 Mar 2011 08:35:04 -0500 > The API will round up so that the correct region covers the API. > However, if you have other structures packed into the space (as very > often happens on stack), you get cache line interference in the CPU if > they get accessed: The act of accessing an adjacent object pulls in > cache above your object and destroys DMA coherence. This is the > principle reason why DMA to stack is a bad idea. Another major real reason we can't DMA on-stack stuff is because the stack is mapped virtually on some platforms. And that is the original reason the restriction was put in place. -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
