Date: Mon, 13 Apr 1998 09:24:39 +0300 (IDT)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: Luke Bishop <lbishop AT calvin DOT stemnet DOT nf DOT ca>
cc: djgpp AT delorie DOT com
Subject: Re: Quick Question: Does CS=DS=SS?
In-Reply-To: <01bd65b6$07134ac0$6848a5c6@technoid>
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On 13 Apr 1998, Luke Bishop wrote:

> I was just wondering if DJGPP always made CS=DS?

One situation where this is tricky is when a signal is pending, like
when you press Ctrl-C or Ctrl-BREAK, or when alarm timer fires.  The
DJGPP signal-handling mechanism works by invalidating the DS selector
and catching the exception generated when the program touches any of
its data.

So programs which rely on DS being valid need to use the alternate
selector called `__djgpp_ds_alias', which is *always* valid.