On Thu, Jun 27, 2019 at 06:25:37PM +0300, Gal Pressman wrote:
> On 27/06/2019 16:58, Michal Kalderon wrote:
> > Create a common API for adding entries to a xa_mmap.
> > This API can be used by drivers that don't require special
> > mapping for user mapped memory.
> >
> > The code was copied from the efa driver almost as is, just renamed
> > function to be generic and not efa specific.
>
> I don't think we should force the mmap flags to be the same for all drivers..
> Take a look at mlx5 for example:
>
> enum mlx5_ib_mmap_cmd {
> MLX5_IB_MMAP_REGULAR_PAGE = 0,
> MLX5_IB_MMAP_GET_CONTIGUOUS_PAGES = 1,
> MLX5_IB_MMAP_WC_PAGE = 2,
> MLX5_IB_MMAP_NC_PAGE = 3,
> /* 5 is chosen in order to be compatible with old versions of libmlx5 */
> MLX5_IB_MMAP_CORE_CLOCK = 5,
> MLX5_IB_MMAP_ALLOC_WC = 6,
> MLX5_IB_MMAP_CLOCK_INFO = 7,
> MLX5_IB_MMAP_DEVICE_MEM = 8,
> };
>
> The flags taken from EFA aren't necessarily going to work for other drivers.
> Maybe the flags bits should be opaque to ib_core and leave the actual mmap
> callbacks in the drivers. Not sure how dealloc_ucontext is going to work with
> opaque flags though?
Yes, the driver will have to take care of masking the flags before
lookup
We should probably store the struct page * in the
rdma_user_mmap_entry() and use that to key struct page behavior.
Do you think we should go further and provide a generic mmap() that
does the right thing? It would not be hard to provide a callback that
computes the pgprot flags
Jason
