crash mode

[Ray <rehenry-at-up.net>]

-----short answer-----
If you have problems with the EMC crashing while running steppermod, the
quick work-around is to run freqmod.  Be sure to uncomment period and set
it large enough for the speed of your PC.

-----problem-----
I believe that there is a problem with steppermod.o.  I am currently using
the BDI on a K6 2-400 with period commented out in the ini file.  I have
also seen the problem on a Cyrix PR300 and I believe that we produced
the problem on one of Matt's PC's during NAMES.

I can often setup a "crash mode" by starting an EMC using steppermod and
minimill definitions.  I home out the machine and start a program in auto
mode.  Key to the problem seems to be a harsh shutdown like xkill or
<control c> or <control d> in the terminal window while the interpreter and
motion stuff is running.  If I abort the running program and shutdown using
file/exit I do not see the same problem.

After I have set up my PC for "crash mode" I restart the same EMC and turn
the machine on.  When I attempt to home an axis, the EMC dies, taking at
least most of the x-window system with it.  Sometimes it will reboot itself
right then.  Sometimes it will lock up everything and require a manual
reboot.

I realize that this is a harsh shutdown of the EMC but I do not seem to get
the same problems with freqmod.o.  I am wondering if something gets left
laying around that reactivates when steppermod restarts.  When I have 
"crash mode" going, I have seen crashes recurr across several reboots so
it is not just garbage in the active modules or the active kernel.  

I have reproduced the problem using emcpanel without any x system, window
manager, or gui running.  I have also found that using the same EMC
directory and all files except an ini that calls freqmod vs one that calls
steppermod, the EMC runs fine using freqmod and crashes using steppermod.  

On some ocasions, I have been able to switch to terminal 2 and log in as
root but can't or don't know how to do much from there.  Other times I
have seen a bunch of error messages on terminal two -- an oops message and
references to linux and something about a pointer to null.

Ssometimes, copying a new steppermod.o file into the plat/realtime/lib
directory will stop the crash mode and the EMC will operate properly with
seppermod.

If you are daring enough to try to reproduce my results, I'd like to
hear what happens with your machine.  Perhaps if enough of us can
consistently crash the EMC, we can figure out why.

Ray