Re: [Xenomai] Add "rtroute solicit" support to the rtnet script and rtnet.conf

[Jeff Webb <jeff.webb@nta-inc.net>]

On 12/17/2014 04:31 AM, Gilles Chanteperdrix wrote:
> On Tue, Dec 16, 2014 at 03:51:16PM -0600, Jeff Webb wrote:
>> I am using rtnet without rtmac/tdma. I previously sent a patch
>> that allows one to use the "rtnet" script and rtnet.conf in this
>> configuration. I would also like to be able to specify a list of
>> IP addresses in rtnet.conf that are passed along to "rtroute
>> solicit". I have attached patches for the rtnet and
>> xenomai-3.git/next repositories. I think others will find them
>> useful.
>
> Well, you should probably be using "nomac" if you are not interested
> in tdma.
>

Thank you for your response.  I appreciate your advice, Gilles, and even more so, since I am new to RTnet.  I am somewhat confused by the rtmac/nomac configuration, since I haven't found a lot of documentation on it.  Something I read indicated that the primary purpose was for use as skeleton when writing new MAC implementations, but it also seems that it is useful for other purposes.  I have a couple questions that might clarify things for me a bit.

There are a couple of ASCII-art drawings at the beginning of the README.rtmac file in the rtnet documentation.  The first one seems to indicate that rtnet can be used without rtmac, if all communication is done from RT applications.  I see that with rtmac inserted, standard linux programs can also send information over the real-time interface.  The RTmac.spec document indicates that the rtmac layer wraps data sent through rtmac with an rtmac frame header, and specifies how the non-real-time packets can be tunneled through a real-time network.  My first question is: does the rtmac/nomac configuration still add the rtmac header?  I assumed the answer was "yes", but perhaps I am wrong.

My initial RTnet application is to send UDP packets in real-time to a hardware device manufactured by someone else.  Since I am not in control of the receiving device, I cannot have any additional headers added to my packets.  Can I do this without the rtmac module inserted?  Can I do this with rtmac and nomac inserted?  If so, what would be the advantage in my application?  At some point I may need to send/receive TCP and UDP packets for non-real-time configuration purposes, but I don't see any need to communicate from standard linux programs at this time.

Thank you again to everyone for their input.  The documentation is not very clear on how (or even if) rtnet can be used to do what I need.

-Jeff