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Re: [Qemu-devel] Re: [PATCH] Reboot CPU on triple fault
From: |
Michal Schulz |
Subject: |
Re: [Qemu-devel] Re: [PATCH] Reboot CPU on triple fault |
Date: |
Wed, 16 Apr 2008 12:25:49 +0200 |
User-agent: |
KMail/1.9.9 |
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
- [Qemu-devel] Re: [PATCH] Reboot CPU on triple fault, Jan Kiszka, 2008/04/15
- Re: [Qemu-devel] Re: [PATCH] Reboot CPU on triple fault, Paul Brook, 2008/04/15
- Re: [Qemu-devel] Re: [PATCH] Reboot CPU on triple fault, Kevin Wolf, 2008/04/16
- Re: [Qemu-devel] Re: [PATCH] Reboot CPU on triple fault, Jamie Lokier, 2008/04/16
- Re: [Qemu-devel] Re: [PATCH] Reboot CPU on triple fault, Antoine Kaufmann, 2008/04/16
- Re: [Qemu-devel] Re: [PATCH] Reboot CPU on triple fault, Kevin Wolf, 2008/04/16
- Re: [Qemu-devel] Re: [PATCH] Reboot CPU on triple fault, Michal Schulz, 2008/04/16
- Re: [Qemu-devel] Re: [PATCH] Reboot CPU on triple fault,
Michal Schulz <=
- Re: [Qemu-devel] Re: [PATCH] Reboot CPU on triple fault, Kevin Wolf, 2008/04/16
- [Qemu-devel] Re: [PATCH] Reboot CPU on triple fault, Jan Kiszka, 2008/04/16
- Re: [Qemu-devel] Re: [PATCH] Reboot CPU on triple fault, Jamie Lokier, 2008/04/16
Re: [Qemu-devel] Re: [PATCH] Reboot CPU on triple fault, Anthony Liguori, 2008/04/16
Re: [Qemu-devel] Re: [PATCH] Reboot CPU on triple fault, Kevin Wolf, 2008/04/16
[Qemu-devel] [PATCH] x86: Reboot CPU on triple fault - Version 3, Jan Kiszka, 2008/04/16