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Date:      Fri, 08 Nov 2002 11:40:52 -0500 (EST)
From:      John Baldwin <jhb@FreeBSD.org>
To:        Matthew Dillon <dillon@apollo.backplane.com>
Cc:        hackers@freebsd.org
Subject:   RE: Int 0x15 and VM86 question
Message-ID:  <XFMail.20021108114052.jhb@FreeBSD.org>
In-Reply-To: <200211081007.gA8A7fwx000751@apollo.backplane.com>

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On 08-Nov-2002 Matthew Dillon wrote:
>     I've been pulling my hair out all night trying to figure out how
>     the hell the VM86 code is able to issue an int 0x15 to the BIOS.
>     I can't find where it gets the interrupt descriptor table entry
>     for int 0x15.  My assumption is that it copies it from the idt
>     supplied by the BIOS but I don't see where.  As far as I can tell
>     FreeBSD loads a pristine IDT that does not have a record for 
>     int 0x15.  So how can the VM86 code issue an int 0x15 and have it
>     find the BIOS?
> 
>     If anyone knows the answer to this, I'm all ears!

I think we use a different IDT for vm86 mode that is basically a
duplicate (if not the original) of the BIOS IDT.

-- 

John Baldwin <jhb@FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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