Problem with shared memory module for ppc

[Wolfgang Grandegger]

On 06/08/2004 05:03 PM Anthony Mallet wrote:
> I am trying to share memory between user space programs and kernel using
> rtai-3.0r4 / linux*PPC*-2.4.26.
> 
> It works fine when I use USE_GFP_KERNEL support, but fails when I want to
> use USE_VMALLOC. And I have to use vmalloc since I want to allocate
> something like 4Mb.
> 
> To be more precise : there is no failure as such. rt_shm_alloc calls in
> kernel or user space return valid addresses, but the memory segments seem
> to be somehow decoupled from each other: I can write and read, but the
> memory is not shared. Again, this works if I use the USE_GFP_KERNEL flag.
> 
> [ And also: I had to manually ln -s /dev/misc/RTAI_SHM /dev/rtai_shm in
> order to test userland functions ]

This is stange!

> I don't know if it's a problem with linuxppc kernel or rtai...
> Any idea?

Could you please send a little test module and program demonstrating the
problem. Then I would give it a try on my TQM860L module.

Wolfgang.