connect raspberry via ehternet as IO-port - some developer help needed

wicki wrote:

the driver uses the IP-layer-communications - not RAW-eth.
and because I havn't found any rtapi_socket-functions, I assume,
thats the reason, this driver is running in userspace.

because no rtapi-socket-funtion exist, a realtime-eth-driver cannot be
written inside linuxcnc.

The history, as I understand it, is that the current userspace hm2_eth was written first a it was easier, and the plan was to then write the rtapi code needed for rtai kernal module access. But it was found that the preempt-rt approach worked so well that there wasn't much motivation for the work involved. Note that RTAI and PREEMPT-RT are both "Realtime" but one is kernel and one is userspace.

There is an ambition to make LinuxCNC a normal application downloadable from the repositiories, but for that to happen it needs to run on mainline kernels, and there is some hope that preempt-rt will be mainlined, so it is worth the trouble of supporting it.

Whether preempt-rt will evet be good enough for software-stepping remains to be seen. I have a machine where it would be entirely usable (my RM One has better latency under preempt-rt than any of my other machines running rtai.). It is possible the preempt-rt might improve to be usable on more hardware.

my raspi-driver is running as a uid-root-thread and the communication
between the linuxcnc virtual parport and the driver is done via shared
memory.

to save some cpu-time, I want to use external function calls instead of
polling the shared memory.

is this a usable solution or do you ave any other ideas to solve this?

This is way outside my are of expertise. Can I suggest that you move this discussion to the developers mailing list? Your chances of catching the core developers on this forum are pretty slim.

and who is the person I have to contact, to get more information about
building a configure/makefile for linuxcnc?

Again, you can try the develpers mailing list. But I don't understand what you are really asking.
For your own use you seem to be suggesting that halcompile works?
If the driver is to be released into the main LinuxCNC distribution then you would just add references to your driver to the existing makefiles. What makes you think that you need to create a new makefile for your driver?