rtnet code in rtai_24.1.12 (from denx)

deepa.vijayaraghavan at mbtech-group.com deepa.vijayaraghavan at mbtech-group.com
Tue Oct 26 09:19:33 CEST 2004


Hello Paolo,
   Thanks a lot for your reply. LXRT is not supported for power PCs, and I 
use an IBM 440 GP power PC based board.
I just need a socket interface to send out data to the outside network, in 
my RT task of lesser priority. The higher priority task does some kind of 
data acquisition. I do not really need the features of RTNET, as my 
realtime requirements are not very stringent in terms of data 
routing(sending it out to the outside world, I mean).
   The call to set_fs(KERNEL_DS) is the one that fails, when called from 
the RT task. I do not understand why. Do you have any example code, that 
uses the netrpc.h(that you'd sent) to make socket calls from RT tasks?

Thanks a lot!

Best Regards
Deepa.




  




mantegazza at aero.polimi.it
25.10.2004 19:35



 
        An:     deepa.vijayaraghavan at mbtech-group.com
        Kopie: 
        Thema:  Re: rtnet code in rtai_24.1.12 (from denx)


deepa.vijayaraghavan at mbtech-group.com wrote:
> 
> Hello Paolo,
>    I tried using the file you had sent, to make socket calls from RTAI. 
> As part of the init_module, I create socket(using ksocket()) and 
> bind(using kbind) the server to the socket. This proceeds without 
errors.
>   I spawn an idle task using rt_init_task(), also in the init_module(). 
> When this task gets scheduled,  it checks the socket with the kpoll(), 
> and sends the data out with the ksendto(). A call to kpoll() from the 
> rt_task results in "StartedOops: kernel access of bad area, sig: 11" 
> error. If I replace kpoll with poll, it goes through, but I get the oops 

> for the ksendto call. I am unable to understand this! Any suggestion is 
> of great help.
> 

YOu cannot use kernel calls in hard real time RTAI kernel tasks For that 
you need to copy a kind of something found in netrpc.h. The best 
solution is to use LXRT and soft kernel threads mixing up RTAI and Linux 
support, but not in real time.

For real time, or using sockets directly from RTAI tasks, _use_RTNet_

Paolo.


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