Re: Differences between program runs with and without gdb

[Andrew STUBBS <andrew dot stubbs at st dot com>]

Christoph Bartoschek wrote:
> There is no stepping and no breakpoints are active. The program starts, it 
> terminates and the debugger is quitted. 

In that case GDB is still quietly and automatically monitoring threads 
and signals, of which you say there are none, and also the dynamic 
linker. I don't know what system you are on or what your program does 
but it may be that there is an invisible breakpoint every time a library 
is loaded (GDB uses them to load the symbols from the library). I don't 
know how that could be affecting anything though. It's possible that a 
breakpoint has been set on some data somehow - if you have a symbol with 
just the wrong name.

Perhaps you pass in slightly different parameters or environment when 
you use GDB. I expect you checked this already.

There's always cache effects of course. Perhaps your program does 
something unsafe (self modifying code?) and GDB's influence is just 
enough to perturb the results.

Instead of GDB, have you tried running it "under" something else. ptrace 
or valgrind perhaps, assuming your on a compatible system.

Well there's some ideas anyway.

Andrew