[Xenomai-help] Re: problem with reading from rt_pipe with a normal linux process

[Marco Jackel <ich@domain.hid>]

Jan Kiszka wrote:
> Marco Jackel wrote:
>> Jan Kiszka wrote:
>>> Hint: read returns its error code in errno. What does that one tell you?
>> read returns -1, "operation not permitted"
>>
> 
> errno == EPERM? A bit weird. Try strace'ing both your program and the
> cat tool to look for a difference.
strace says "-1" in this case is ENOBUFS

The failure in my programm is that it writes binary data to a pipe with
rt_pipe_write (preserves message boundary) and normal linux process
wants to read it byte by byte with read(). Read wants to receive the
whole message, but the message is bigger than 1 byte, so it returns ENOBUFS.

The solution is to use rt_pipe_stream (don't preserves message
boundary). Do I have to use rt_pipe_alloc before? Is there a small
sample program somewhere?


Thanks,
Marco