Hi Stuart, There is no code in RTLinux's rtl_fifo.c to support FIONREAD (can be easily added though). So I don't see how it can work at all. Michael. Stuart Warren ([EMAIL PROTECTED]) wrote: > Hi Laurent, > > I noticed the other day that if I did a (rtl 3.0 pre6d) > > ioctl(fifo_fd, FIONREAD, unread); > > it would work okay until I emptied the fifo but after that (and after > some more data accumulated in the fifo), it would continue to return 0. > > I haven't looked through the fifo code but it sounds similar to what you > are experiencing with RAT. > > cheers, > > Stuart Warren > > [EMAIL PROTECTED] wrote: > > > > Hello, > > > > I've found a "undocumented feature" in the RTAI fifos (new fifos (both version >0.9a and 1.5)). We are unable to perform a select system call from a user-space >program (actually this is a TCL script that use the filevent TCL feature, but if you >look > > through strace you can actually see that this is a call to select with a >filedescriptor corresponding to the FIFO). Although the real-time process perform a >write on the FIFO, the user-space process doesn't wake-up. We observed that it sleeps >on the select > > system call. > > > > The only work-around we had, is to have a separate user-space process that does a >blocking read on the RT-FIFO and then we something is written, reads the RT-FIFO and >rewrite the information on named pipe on which the script is now sleeping. This works > > but, it's not very elegant and it wastes CPU power. > > > > Thanks for your help. > > > > Laurent Kersten > > -- [rtl] --- To unsubscribe: echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR echo "unsubscribe rtl <Your_email>" | mail [EMAIL PROTECTED] --- For more information on Real-Time Linux see: http://www.rtlinux.org/rtlinux/
