network communication

[Jan Kiszka]

Alexander Eisenhuth schrieb:
> 
> 
> Jan Kiszka wrote:
> 
>> Alexander Eisenhuth schrieb:
>> > ...
>>
>>>
>>> RTNet
>>> =====
>>> I've read in the archive about RTNet.  It sound exactly what I need, 
>>> but unfortunatly the chipset I'm using is not supported.
>>>
>>> * Can anyone say something about the dependencies to the chipset ? At 
>>> a first look there seems to be no abstract approach to "soften" the 
>>> support of new Cards.
>>>
>>
>> If you only want soft real-time networking with a RTAI kernel API, you 
>> could use the RTnet-wrapper for net_rpc. It comes with current RTAI 
>> versions.
> 
> 
> What priorities are raised in that case ? Can you loose a few words on 
> net_rpc ?
> 

I would say (without knowing everything in details) that no priorities 
are raised. All incoming and outgoing udp data is treated as any other 
linux tcp/udp/ip packets. That means everything happening in the 
RT-domain has higher priority than your udp packets - even if the 
rt-priority of that tasks are lower than you sender or receiver. And in 
linux, there is no change of priorities at all.

About net_rpc: we haven't tried it for months here at the RTS (at the 
moment we do need it). If it already works with RTnet, you get a remote 
procedure call mechanism for most RTAI functions over ethernet. Maybe 
Paolo has already made some experiments with current RTnet and net_rpc...

Jan


-- 
Dipl.-Ing. Jan Kiszka

Institute for Systems Engineering, Department of Real-Time Systems (RTS)
Appelstraße 9A, D-30167 Hannover
phone +49 511 762-3974 / fax +49 511 762-4012
http://www.rts.uni-hannover.de