Re: Calculating kernel logical address ..

Andrew Morton
2002-09-09T18:38:49Z

Jesse Barnes wrote:
>
> On Mon, Sep 09, 2002 at 02:00:35PM -0400, Richard B. Johnson wrote:
> > Well I just read Documentation/DMA-mapping.txt as advised by David
> > and it seems as though it will no longer be possible to do what
> > many programmers have been wanting to do, to wit:
> >
> > (1) In user-code, allocate a buffer.
> > (2) Lock that buffer into memory.
> > (3) Call some driver that DMAs data to/from that buffer.
>
> It looks drivers/media/video/video-buf.c uses alloc_kiovec() and
> map_user_kiobuf() to do it.

For video-buf.c and for Imran's application, that's just a wrapper
which is used to get at get_user_pages().

It would be best to not use the kiobuf code please - its future is
up in the air. Just use get_user_pages() directly for now.