Re: [RFC PATCH 6/6] sparc64: Enable 64-bit DMA

[tndave]

On 10/07/2016 12:32 AM, Christoph Hellwig wrote:
> On Thu, Oct 06, 2016 at 04:33:36PM -0700, Tushar Dave wrote:
> > ATU 64bit addressing allows PCIe devices with 64bit DMA capabilities
> > to use ATU for 64bit DMA.
>
> Any chance to always enable this?  Last I checked sparc was the only
> architecture still using a 32-bit dma_addr_t, leading to some fun
> breakage in things like the software RDMA drivers that abuse it to
> store a kernel pointer..
With change made by patch 6/6, dma_addr_t is always 64-bit, no matter if
device DMA mask is 32-bit (i.e. using existing IOMMU) or 64-bit (i.e
using ATU)

-Tushar

>