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Date: Thu, 14 Oct 1999 12:55:47 +0300 (EET DST)
From: Esa A E Peuha <peuha AT cc DOT helsinki DOT fi>
Sender: peuha AT cc DOT helsinki DOT fi
To: djgpp-workers AT delorie DOT com
Subject: Re: Debugging programs with SIGALRM
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On Sun, 10 Oct 1999 Eli Zaretskii <eliz AT is DOT elta DOT co DOT il> wrote:

> Does someone have any idea what might be the reason?  It seems like
> some window of opportunity is opened when the thread jumps between the
> debugger and the debuggee, whereby if the exception generated by the
> timer handler happens inside that window, it causes bad things.  I'm
> almost sure I see ESP and EBP that don't belong to each other in the
> registers' dump when the debuggee crashes.

> Is it possible that this is because longjmp doesn't disable interrupts
> when it fiddles with SS:ESP?  Should we CLI there?

CLI would hardly be of any use, because the processor already disables 
interrupts (and some exceptions) between a load to SS and the following 
instruction (a load to ESP in this case).  However, longjmp doesn't clear
the NT flag before issuing IRET, which will cause interesting results if
NT happens to be set for some reason.

-- 
Esa Peuha
student of mathematics at the University of Helsinki
http://www.helsinki.fi/~peuha/