Re: [Xenomai-help] RTDM mmap and DMA

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

Fillod Stephane wrote:
 > Gilles Chanteperdrix wrote:
 > >Fillod Stephane wrote:
 > > > Perrine Martignoni wrote:
 > > > >Currently, I write an RTDM module and I would like to do DMA and
 > mmap
 > > > to perform transfers who have hard constraints.
 > > > >I would like to know if there is an example in a driver who would
 > help
 > > > me to do this.
 > > > 
 > > > I'm looking for the same need, except I'm not using RTDM, and
 > everything
 > > > is in userland. Using the attached patch against Xenomai 2.4.0, I
 > hope
 > > > to make it to work with something like this:
 > >
 > >I propose the attached modifications. Is it Ok for you ?
 > 
 > Yes, your patch is much cleaner, esp. wrt KMALLOC_MAX_SIZE which I was
 > not aware of.
 > 
 > The documentation needs an update, and a link to RT_HEAP_INFO.
 > Does any Doxygen guru knows how to make rt_heap_inquire a hyperlink
 > in the above chunk?

Ok. I merged the patch I sent, as well as this patch (fixed to make
rt_heap_inquire a hyperlink) in trunk. However, I did not commit it in
the v2.[34].x branch, since it is a patch which breaks the ABI (size of
the rt_heap_info structure changes). Should I increment the ABI revision
?

 > 
 > --- ksrc/skins/native/heap.c    17 Dec 2007 14:36:15 -0000      1.6
 > +++ ksrc/skins/native/heap.c    27 Dec 2007 15:23:06 -0000
 > @@ -201,8 +201,8 @@
 >   *
 >   * - H_DMA causes the block pool associated to the heap to be
 >   * allocated in physically contiguous memory, suitable for DMA
 > - * operations with I/O devices. A 128Kb limit exists for @a heapsize
 > - * when this flag is passed.
 > + * operations with I/O devices. The physical address of the
 > + * heap can be obtained by a call to rt_heap_inquire.
 >   *
 >   * @return 0 is returned upon success. Otherwise:
 >   *
 > --- include/native/heap.h       17 Dec 2007 14:36:09 -0000      1.2
 > +++ include/native/heap.h       27 Dec 2007 15:34:22 -0000
 > @@ -34,6 +34,10 @@
 >  #define H_SINGLE   0x400       /* Manage as single-block area. */
 >  #define H_SHARED   (H_MAPPABLE|H_SINGLE) /* I.e. shared memory segment.
 > */

Beware: your mailer broke your patch by adding a newline. It may be a
better idea to send the patch as a plain text attachment, it avoids such
surprises. I have already seen a site explaining how to teach your
mailer not to do this, but I do not have the URL at hand.

 > 
 > +/** Structure containing heap-information useful to users.
 > + *
 > + *  @see rt_heap_inquire()
 > + */
 >  typedef struct rt_heap_info {
 > 
 >      int nwaiters;              /* !< Number of pending tasks. */
 > 
 > Thanks!
 > -- 
 > Stephane


-- 


					    Gilles Chanteperdrix.