From owner-freebsd-hackers Fri Nov 8 21: 7:20 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 9063037B401 for ; Fri, 8 Nov 2002 21:07:19 -0800 (PST) Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3FB1D43E3B for ; Fri, 8 Nov 2002 21:07:19 -0800 (PST) (envelope-from dillon@apollo.backplane.com) Received: from apollo.backplane.com (localhost [127.0.0.1]) by apollo.backplane.com (8.12.5/8.12.5) with ESMTP id gA957AFC005518; Fri, 8 Nov 2002 21:07:10 -0800 (PST) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.12.5/8.12.5/Submit) id gA957AZa005517; Fri, 8 Nov 2002 21:07:10 -0800 (PST) (envelope-from dillon) Date: Fri, 8 Nov 2002 21:07:10 -0800 (PST) From: Matthew Dillon Message-Id: <200211090507.gA957AZa005517@apollo.backplane.com> To: "Luoqi Chen" Cc: Subject: Re: RE: Int 0x15 and VM86 question References: Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG :When iopl is less than 3 (that's what our kernel is running at), the :soft interrupts in vm86 are not dispatched through the normal protective :mode idt vector. Depending on your vme setting and interrupt redirection :bitmap, it either triggers a general protection fault (vme clear and redir :bit set), or directly jumps to vector at low memory as in real mode (vme :set and redir bit clr). IIRC vme is available for P5 or later processors. :So for you it most likely is the direct jump. The first page of physical :memory (which contains the BIOS vectors) is not touched by the kernel, :and is mapped at address 0 in the vm86 process space. : :Does this answer your question, Matt? It has been quite a while since :I looked at the stuff, some of the descriptions might not be accurate. : :-lq Ah ha! You are a great help Luoqi. I was so focused on the interrupt descriptor tables that I forgot that they can be ignored in virtual 8086 mode. I dunno in regards to the IOPL, I'll look into that, but you've definitely hit the nail on the head. Thanks a bunch! -Matt Matthew Dillon To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message