From: Michal Schulz <michal.schulz@gmx.de>
To: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] Re: [PATCH] Reboot CPU on triple fault
Date: Wed, 16 Apr 2008 12:25:49 +0200 [thread overview]
Message-ID: <200804161225.49791.michal.schulz@gmx.de> (raw)
In-Reply-To: <200804161217.33019.michal.schulz@gmx.de>
On Wednesday 16 April 2008, Michal Schulz wrote:
> > I have to admit that I'm all but an 286 PM expert. What exactly is a
> > triple fault doing there? If it leads to a reset as implemented here, I
> > can hardly imagine that it is of much use in regular context switching.
>
> It is required due to the "feature" of 286 CPU. Once 286 enters protected
> mode, it cannot be switched back to the real mode. The only way to perform
> it is resetting the CPU. A software which tries to go back from protected
> to real mode sets the warm-reset vector in BIOS memory area, sets the
> reboot reason variable in CMOS memory and issues a CPU reset.
>
> CPU may be resetted due to a triple fault :)
and some example code using it (with comments):
http://www.x86.org/ftp/source/3fault/reset.asm
--
Michal Schulz
next prev parent reply other threads:[~2008-04-16 10:25 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-29 18:13 [Qemu-devel] [PATCH] Reboot CPU on triple fault Hervé Poussineau
2008-03-30 1:36 ` Alexander Graf
2008-03-31 9:52 ` Kevin Wolf
2008-04-15 16:05 ` [Qemu-devel] " Jan Kiszka
2008-04-15 16:57 ` Paul Brook
2008-04-16 8:37 ` Kevin Wolf
2008-04-16 9:23 ` Jamie Lokier
2008-04-16 9:51 ` Antoine Kaufmann
2008-04-16 9:53 ` Kevin Wolf
2008-04-16 10:17 ` Michal Schulz
2008-04-16 10:25 ` Michal Schulz [this message]
2008-04-16 12:08 ` Kevin Wolf
2008-04-16 10:22 ` Jan Kiszka
2008-04-16 11:34 ` Jamie Lokier
2008-04-16 14:44 ` Anthony Liguori
2008-04-16 8:18 ` Kevin Wolf
2008-04-16 12:02 ` Jan Kiszka
2008-04-16 12:09 ` Avi Kivity
2008-04-16 12:36 ` Kevin Wolf
2008-04-16 12:57 ` Jamie Lokier
2008-04-16 12:44 ` [Qemu-devel] [PATCH] x86: Reboot CPU on triple fault - Version 3 Jan Kiszka
2008-04-16 13:35 ` [Qemu-devel] [PATCH] x86: Reboot CPU on triple fault - Version 4 Kevin Wolf
2008-04-16 14:18 ` [Qemu-devel] " Jan Kiszka
2008-04-16 14:33 ` [Qemu-devel] [PATCH] x86: Reboot CPU on triple fault - Version 5 Kevin Wolf
2008-04-16 14:57 ` [Qemu-devel] [PATCH] x86: Reboot CPU on triple fault - Version 6 Kevin Wolf
2008-04-17 9:52 ` [Qemu-devel] " Jan Kiszka
2008-04-18 14:06 ` [Qemu-devel] " Anthony Liguori
2008-04-21 11:53 ` Kevin Wolf
2008-05-26 14:46 ` [Qemu-devel] " Jan Kiszka
2008-05-27 16:01 ` [Qemu-devel] [PATCH] x86: Reboot CPU on triple fault - Version 8 Jan Kiszka
2008-05-27 16:17 ` [Qemu-devel] " Jan Kiszka
2008-04-16 14:37 ` [Qemu-devel] Re: [PATCH] x86: Reboot CPU on triple fault - Version 4 Anthony Liguori
2008-04-17 8:07 ` Jan Kiszka
2008-04-17 12:49 ` Anthony Liguori
2008-04-17 14:10 ` Jan Kiszka
2008-04-17 18:30 ` Anthony Liguori
2008-04-17 19:24 ` Jan Kiszka
2008-04-18 8:38 ` Kevin Wolf
2008-04-18 14:08 ` Anthony Liguori
2008-04-21 9:37 ` Kevin Wolf
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