From: ebiederm@xmission.com (Eric W. Biederman)
To: Jamie Lokier <jamie@shareable.org>
Cc: Andi Kleen <ak@suse.de>, joe briggs <jbriggs@briggsmedia.com>,
linux-kernel@vger.kernel.org
Subject: Re: software reset
Date: 30 Apr 2003 05:04:59 -0600 [thread overview]
Message-ID: <m1llxsfdpg.fsf@frodo.biederman.org> (raw)
In-Reply-To: <20030430075004.GB13859@mail.jlokier.co.uk>
Jamie Lokier <jamie@shareable.org> writes:
> Andi Kleen wrote:
> > The most reliable way is to force a triple fault; load zero into
> > the IDT register and then trigger an exception. The linux kernel
> > does that in fact for reboot and so far I haven't seen any machine failing
> > to reset yet.
>
> There are some 486s which don't boot on triple fault, nor on asking
> the keyboard controller to pulse the reset line. Hence the 3rd option,
> "reboot=bios".
And as an interesting data point all a triple fault does on a modern
system is to put the cpu in a weird stopped state. Some hardware
usually the southbridge then detects this and if properly configured
will trigger the reset line.
I believe this may actually go back into history as far as the 486 but
I have not done the researched to see how far back this behavior goes.
Eric
next prev parent reply other threads:[~2003-04-30 10:55 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200304291037.13598.jbriggs@briggsmedia.com.suse.lists.linux.kernel>
2003-04-29 15:19 ` software reset Andi Kleen
2003-04-30 7:50 ` Jamie Lokier
2003-04-30 11:04 ` Eric W. Biederman [this message]
2003-04-30 16:15 ` Gabriel Paubert
2003-04-30 17:02 ` Eric W. Biederman
2003-04-30 17:19 ` Gabriel Paubert
2003-04-30 19:31 ` Jamie Lokier
2003-04-30 23:00 ` Rafael Santos
2003-04-30 23:14 ` Andi Kleen
2003-04-30 23:20 ` H. Peter Anvin
2003-05-07 6:55 Perez-Gonzalez, Inaky
-- strict thread matches above, loose matches on Subject: below --
2003-04-29 14:37 joe briggs
2003-04-30 23:12 ` James Stevenson
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