Re: [Xen-devel] [PATCH] Revert "swiotlb: remove SWIOTLB_MAP_ERROR"

From: Christoph Hellwig
Date: Fri Mar 08 2019 - 10:24:03 EST

On Tue, Mar 05, 2019 at 09:41:46AM +0000, Julien Grall wrote:
> On Xen, dma_addr_t will always be 64-bit while the phys_addr_t will depend
> on the MMU type. So we may have phys_addr_t smaller than dma_addr_t from
> the kernel point of view.

How can dma_addr_t on arm have value > 32-bit when physical
addresses are 32-bit only?