From owner-freebsd-ia32  Wed Mar 21 11:32:41 2001
Delivered-To: freebsd-ia32@freebsd.org
Received: from freefall.freebsd.org (freefall.freebsd.org [216.136.204.21])
	by hub.freebsd.org (Postfix) with ESMTP
	id 3DF7137B78D; Wed, 21 Mar 2001 11:32:19 -0800 (PST)
	(envelope-from rnordier@FreeBSD.org)
Received: (from rnordier@localhost)
	by freefall.freebsd.org (8.11.1/8.11.1) id f2LIQDq98641;
	Wed, 21 Mar 2001 10:26:13 -0800 (PST)
	(envelope-from rnordier)
From: <rnordier@FreeBSD.org>
Message-Id: <200103211826.f2LIQDq98641@freefall.freebsd.org>
Subject: Re: Fix BTX to handle early kernel traps
In-Reply-To: <XFMail.010320110036.jhb@FreeBSD.org> from John Baldwin at "Mar 20, 2001 11: 0:36 am"
To: jhb@FreeBSD.org (John Baldwin)
Date: Wed, 21 Mar 2001 10:26:03 -0800 (PST)
Cc: rnordier@FreeBSD.org, ia32@FreeBSD.org
X-Mailer: ELM [version 2.4ME+ PL43 (25)]
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: owner-freebsd-ia32@FreeBSD.ORG
Precedence: bulk
X-Loop: FreeBSD.org

John Baldwin wrote:

> I managed to really hose my kernel by slightly breaking an assertion in
> mtx_init() and calling panic() as a result.  The only problem is that the
> mtx_init() in question was done in init386 before the kernel IDT was setup,
> so the actual fault's that ensued ended up hitting the BTX exception handler.
> This was all nice and good except that when BTX tried to halt it wound up
> recursively page faulting on itself because the kernel had enabled paging, but
> BTX was not compiled with paging.  Furthermore, the gdt had changed out from
> under BTX, so during the exit: target I also had to reload the gdt descriptor
> register before finessing the selectors and returning to real mode.  The
> included patch does all of this and I'd like to commit it:

> [ . . . ]

> Any objections?

Fine by me.

--
Robert Nordier

rnordier@nordier.com  //  Le monde est plein de fous, et qui n'en veut pas voir
rnordier@FreeBSD.org  //  Doit se tenir tout seul, et casser son miroir.

To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-ia32" in the body of the message