Common Driver Model for RTAI
gilles.chanteperdrix at laposte.net
Fri Jul 1 14:15:38 CEST 2005
Jan Kiszka wrote:
> [off-topic] Shared memory between kernel und user space POSIX
> applications? What more beyond the existing mmap will be needed? To
> setup shm between fusion processes, standard mmap already works, there
> is nothing special in my eyes.
Kernel-space and user-space have to share the same namespace for
shm_open. There are two ways to do this, one is to have an RTAI-only
namespace, and to implement an mmap for user-space pretty much the same
way as rt_heap_bind for the native skin.
> > You said that each driver has a set of non-rt entry points. So, I
> > imagined, but I may be wrong, that these entry points are use to map
> > usual Linux device file descriptors to RTDM drivers. Now the question
> > was about how this mapping was done.
> The non-rt entry points are not mapped to the standard Linux namespace.
> You are just free (as far as the driver supports it) to call the RTDM
> API also from non-rt contexts. Tthat's all. No magic here.
But if I understood correctly, the RTDM API is the same as the standard
API. You mean that there is an RTDM version of "select" which can not
sleep on standard file descriptors ?
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