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X-Authentication-Warning: thing1-200.fsi.com: ford owned process doing -bs
Date: Thu, 4 Mar 2004 10:33:37 -0600 (CST)
From: Brian Ford <ford AT vss DOT fsi DOT com>
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Subject: Re: Snapshot 20040225: make hangs/errors out
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Um..., stupid question.  As usual, I haven't thought about this much, or
traced it too far yet, but...

__sigbe begins by pushing ebx, edx, and eax.  It ends by poping just eax
and edx.  Why don't you need to pop ebx?

On Thu, 4 Mar 2004, Christopher Faylor wrote:

> I see what is causing the symptom but not what is causing the problem.
> I spent a sleepless night modelling multi-threaded signal interrupts
> in my head but I'm still not any closer to understanding the problem.
>
> The problem is that malloc allocates some memory, puts the address of
> the memory in the eax register, and then returns.  In the meantime, two
> signals have come in, so rather than return immediately, malloc returns
> to the signal handler and then the signal handler is called again.  In
> some cases, this causes the eax register to become zero and so make
> (rightly) complains.  In theory, this shouldn't happen since the eax
> register should have been saved on the stack.
>
> Nope.  Typing an explanation doesn't help me figure this out.  Bummer.
>

-- 
Brian Ford
Senior Realtime Software Engineer
VITAL - Visual Simulation Systems
FlightSafety International
Phone: 314-551-8460
Fax:   314-551-8444

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