From mboxrd@z Thu Jan  1 00:00:00 1970
From: Steven Seeger <steven.seeger@nasa.gov>
Reply-To: <steven.seeger@nasa.gov>
Date: Sat, 6 Oct 2018 02:35:46 -0400
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Subject: Re: [Xenomai] Does RTNET supports TCP?
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To: xenomai@xenomai.org
Cc: "Pham, Phong" <phamp@ddc-web.com>, "Hillman, Robert" <hillman@ddc-web.com>

On Thursday, October 4, 2018 9:02:46 PM EDT Pham, Phong wrote:
> Hi,
> 
> I noticed starting Xenomai 3.0.1 until now (3.0.7), there is net/ in
> .../kernel/drivers/ and in ../kernel/drivers/net/stack/ipv4/Kconfig
> 
> # source "drivers/xenomai/net/stack/ipv4/tcp/Kconfig"

I don't know why this is commented out. It looks like Gilles's initial import 
of this file in commit 106ffba7b55d506143966ff16158ee79b0007336 had it 
commented out.

I know that UDP is typically used with RTNET. TCP is complicated and has a lot 
of timers and dynamic state that makes it less than desirable for hard-
realtime systems. Probably Jan should chime in on this. I think he has the 
most experience using RTnet at this point.

> 5)      When I created a socket with rt_dev_socket(AF_INET, SOCK_STREAM, 0);
> and attempting to rt_dev_connect(fd, server_ip_addr,
> sizeof(server_ip_addr)), I get errno = 25 (Inappropriate ioctl for device).
>  Does it mean b/c TCP is not supported in RTnet and I attempt to connect
> via TCP (w/ socket SOCK_STREAM)?

Sorry I can't answer the other questions, as I am not working on rtnet myself. 
However, I would suspect that since TCP doesn't compile that is why 
SOCK_STREAM is not working. Try SOCK_DGRAM and see if it works. If not, then 
are you sure you have rtnet drivers for your network device compiled and ready 
to use? Remember, the driver for your network device must be realtime-safe. I 
recall seeing a guide for some simple changes to make to a Linux ethernet 
driver to use as a starting point for porting it to RTNET, but I can't seem to 
find it. Anyone?

Steven