From owner-freebsd-emulation  Mon Jan 19 05:07:20 1998
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Date: Tue, 20 Jan 1998 00:04:52 +1100
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199801191304.AAA13791@godzilla.zeta.org.au>
To: bde@zeta.org.au, mike@smith.net.au
Subject: Re: DOSCMD: Problems w/ Quicken
Cc: emulation@FreeBSD.ORG, gurney_j@resnet.uoregon.edu, rhh@ct.picker.com,
        shmit@erols.com
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>> >Yeah, that's all fine, but what I *don't* understand is why it should 
>> >be trapping as it does claiming that 'movw (%bx),%ax' is an illegal 
>> >instruction.
>> 
>> When %bx = 0xffff, it should cause exception 13 (general protection)
>> in real mode.  IIRC, this is one of the main differences between 8086's
>> and later86's in real mode.
>
>A difference implies two different behaviours.  A GPF is one, what is 
>the other (presumably that taken by the 8086)?

Doesn't matter.

>Would you guess that this might be a CPU-type detection fragment?

I would guss it is a bug in the signal handling.  GPF should be translated
to SIGBUS with code T_PROTFLT + BUS_SEGM_FAULT and sigbus() should generate
a different fatal error.

Bruce