TFTP driver changes

Joel Sherrill joel at
Wed Sep 26 19:10:02 UTC 2001

Gunter Cieters wrote:

> All,
> We are running the RTEMS native host environment (Linux
> target) on a standard Linux Redhat 7.1 distribution. Lateley,
> we are bugged by some RTEMS crashes on a dual P4
> xeon system. The crashes disappear when we boot Linux
> in uniprocessor mode.
> Is there anybody who would know a reason why the RTEMS
> host environment would not run on the P4 SMP system ? (we
> would like to rule out RTEMS and proceed in upgrading the Linux
> kernel but it is a little bit weird that the crashes only
> appear when we are doing RTEMS runs).

This is an interesting one that I have never heard of before.  The
RTEMS unix port (aka synthetic target) runs completely in user space as
a normal Linux process.  It only uses a handful of Linux system operations
like sigalarm and signal processing for a clock tick and setjmp/longjmp for
context switches.  I don't know anything it can do that should trip up the
kernel directly UNLESS ...

<hypothesis mode on>

RTEMS could be using some service heavily that is not truly MP safe.
For example, we repeatedly fire the clock tick.  Say that there is a bug
in the signal processing code that our heavy use of SIGALRM is tripping.

My gut feeling is that RTEMS is somehow tripping a bug where something
is not properly protected in Linux.

<hypothesis mode off> 

Does the kernel crash or just the RTEMS application?

> best regards,
> Gunter Cieters

Joel Sherrill, Ph.D.             Director of Research & Development
joel at                 On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
Support Available                (256) 722-9985

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