Re: [PATCH for-next 2/4] RDMA/hns: Add IOMMU enable support in hip08

Wei Hu (Xavier)
2017-11-09T01:30:08Z

On 2017/11/7 23:48, Jason Gunthorpe wrote:
> On Tue, Nov 07, 2017 at 10:45:29AM +0800, Wei Hu (Xavier) wrote:
>
>> We reconstruct the code as below:
>> It replaces dma_alloc_coherent with __get_free_pages and
>> dma_map_single functions. So, we can vmap serveral ptrs returned by
>> __get_free_pages, right?
> Can't you just use vmalloc and dma_map that? Other drivers follow that
> approach..
>
> However, dma_alloc_coherent and dma_map_single are not the same
> thing. You can't touch the vmap memory once you call dma_map unless
> the driver also includes dma cache flushing calls in all the right
> places.
>
> The difference is that alloc_coherent will return non-cachable memory
> if necessary, while get_free_pages does not.
>
> Jason

Hi, Jason
Thanks for your suggestion.
We will fix it.

Regards
Wei Hu

>
> .
>

--
To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html