Re: DMA-API attr - DMA_ATTR_NO_KERNEL_MAPPING

[Christoph Hellwig]

On Wed, Jun 26, 2019 at 10:12:45PM +0530, Pankaj Suryawanshi wrote:
> [CC: linux kernel and Vlastimil Babka]

The right list is the list for the DMA mapping subsystem, which is
iommu@xxxxxxxxxxxxxxxxxxxxxxxxxxx  I've also added that.

> > I am writing driver in which I used DMA_ATTR_NO_KERNEL_MAPPING attribute
> > for cma allocation using dma_alloc_attr(), as per kernel docs
> > https://www.kernel.org/doc/Documentation/DMA-attributes.txt  buffers
> > allocated with this attribute can be only passed to user space by calling
> > dma_mmap_attrs().
> >
> > how can I mapped in kernel space (after dma_alloc_attr with
> > DMA_ATTR_NO_KERNEL_MAPPING ) ?

You can't.  And that is the whole point of that API.