Nilanjan Roychowdhury wrote:
> Hi
> 
> What is the best IPC ( in terms of performance) between any user space
> XENOMAI task and a user space Linux thread ?
> 
> I know pipes can be used between kernel space XENOMAI task and user
> space Linux thread ?

For larger blocks: shared memory.

We added the rtdm_mmap_to_user service for this purpose.
You can build up an interface on to of it (some IOCTL to establish a
memory region with a user process, some furthers to inform the user
about a valid data block and to signal the driver about the end of
processing that block). This even allows to export DMA memory directly
to the user, i.e. providing zero-copy. Already successfully applied on
an (unpublished) framegrabbing driver.

Jan