From mboxrd@z Thu Jan  1 00:00:00 1970
From: peter.jeremy@alcatel.com.au (Peter Jeremy)
Date: Tue, 15 Nov 2005 14:40:24 +1100
Subject: [TUHS] Redoing "V6on286" or porting V7...?
In-Reply-To: <04fd01c5e991$e8d06b70$6401a8c0@gregnewport>
References: <20051113201609.GW6574@gsmx07.alcatel.com.au>
	<04fd01c5e991$e8d06b70$6401a8c0@gregnewport>
Message-ID: <20051115034024.GJ6574@gsmx07.alcatel.com.au>


On 2005-Nov-14 19:08:52 -0800, Greg Haerr <greg at censoft.com> wrote:
>>  One
>> crucial difference is that Unix has the implicit assumption that the
>> stack is in the data space - which is not true on the 286.  This
>> difference is fairly critical to Unix and makes it impossible to
>> accurately reproduce the traditional Unix memory protection.
>
>I don't understand this.  If SS is set to DS, in any 16 bit mode,
>then doesn't this accomplish the accurate reproduction?  I realize
>that a 32-bit mode would be required for limit checking.

You can make SS and DS the same but this means that there's nothing
stopping the stack growing down into the heap or vice versa.  This
makes the stack accessible from the data space but gives no protection
(note that I was referring to reproducing Unix protection).

-- 
Peter Jeremy

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