Re: SCSI disk problems - Don't know where to begin

[dennison@telepath.com]

In article <70lj95$s66$1@nnrp1.dejanews.com>,
  krichey@nswc.navy.mil wrote:
> I am writing some data extraction code in Ada (Greenhills) in a VxWorks,
> PowerPC, VME card cage system, with a SCSI disk.  VME-167 cards
> Also there are some C tasks.
>
> At some point (it varies, and doesn't happen every time) the best we can tell

That generally is the hallmark of a race condition. You may want to go back
over the code to make sure *any* object accessed by more than one task
(except via a rendezvous) either has a "pragma atomic", or is placed in a
protected type.

> One guess is something is 'jumping its bounds' and messing up memory where the
> device driver resides- but what?  Any ideas?

If you suspect that, try to catch it happening. If you are using AdaMulti,
check out the section on "Watchpoints" in the debugger command list in your
AdaMulti reference manual. You should be able to set the debugger up to stop
any task that tries to modify a designated area of memory. In my AdaMulti for
Windows Reference Manual (v 1.8.8), the relevant discussion is on page 252.

Race conditions happen to the best of us. But if a rougue task is really
trashing other's code space, that's a different matter entirely. Whoever wrote
that code is in dire need of a "swirlee". >:-)

--
T.E.D.

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