Re: inverse mmap() available?

[Christoph Hellwig]

In article <[e-mail]> you wrote:

> Hello!
>
> Is there a way to map user space memory into kernel address space, e.g.
> that i don't have to call get_user(var,...) but simply use var =
> *user_space_ptr?
>
> What i intend to do (as the next step) is to DMA-transfer data directly
> between a PCI device and user space memory. The buffer in user space
> should be allocated with malloc(), so allocating a buffer in kernel and
> mmap()-ping it to user space is not the solution..
>
> I guess this has been asked before, any links to further information
> would be great.

map_user_kiobuf is what you want :) Some more explanation at:

 ftp://ftp.openlinux.org/pub/people/hch/kio/kiobuf.txt