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From: Jamie Lokier <jamie@shareable.org>
To: Andi Kleen <ak@muc.de>
Cc: torvalds@transmeta.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Use correct x86 reboot vector
Date: Sat, 10 May 2003 17:15:29 +0100	[thread overview]
Message-ID: <20030510161529.GB29271@mail.jlokier.co.uk> (raw)
In-Reply-To: <20030510025634.GA31713@averell>

Andi Kleen wrote:
> Extensive discussion by various experts on the discuss@x86-64.org
> mailing list concluded that the correct vector to restart an 286+ 
> CPU is f000:fff0, not ffff:0000. Both seem to work on current systems, 
> but the first is correct.

You are right.  That's what a 286 does when the RESET signal is asserted.

Which is amazing, because I wrote that ffff:0000 and I was reading
from the Phoenix BIOS book at the time.  It was long ago but I'm
fairly sure I got that address from the book.

I just did some Googling and found that there examples of DOS code
fragments using both vectors.  Also, the original IBM BIOS (as they
say) had a long jump at the vector, which is presumably one of the
many de facto ABIs which real mode programmers grew to depend on.

> See the "DPMI on AMD64" and "Warm reboot for x86-64 linux" threads
> on http://www.x86-64.org/mailing_lists/list?listname=discuss&listnum=0 
> for more details.

One would hope that AMD64 systems, being a new design and all, offer a
documented and reliable method of rebooting.

It should never be necessary to have to write "reboot=..." on the
kernel command line to choose which legacy method works on different
AMD64 motherboards.  Am I too idealistic?

-- Jamie

  parent reply	other threads:[~2003-05-10 16:03 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-05-10  2:56 [PATCH] Use correct x86 reboot vector Andi Kleen
2003-05-10  3:35 ` CaT
2003-05-10  3:58   ` H. Peter Anvin
2003-05-10 14:49   ` Alan Cox
2003-05-10 16:17     ` Jamie Lokier
2003-05-10 18:47       ` Jos Hulzink
2003-05-11 18:01     ` Eric W. Biederman
2003-05-11 17:24       ` Alan Cox
2003-05-11 19:04         ` Eric W. Biederman
2003-05-12  5:48         ` [PATCH] always shutdown on the bootstrap processor Eric W. Biederman
2003-05-10 16:15 ` Jamie Lokier [this message]
2003-05-10 17:09   ` [PATCH] Use correct x86 reboot vector Randy.Dunlap
2003-05-10 19:41   ` Jos Hulzink
2003-05-10 18:10     ` Jamie Lokier
2003-05-10 20:55       ` Jos Hulzink
2003-05-11  3:50       ` Linus Torvalds
2003-05-11  9:37         ` Jos Hulzink
2003-05-11 14:01           ` Jamie Lokier
2003-05-11 17:38             ` Davide Libenzi
2003-05-11 17:56               ` Eric W. Biederman
2003-05-11 18:23                 ` Davide Libenzi
2003-05-11 19:12                   ` Eric W. Biederman
2003-05-12 15:36                     ` Maciej W. Rozycki
2003-05-13  6:35                     ` H. Peter Anvin
2003-05-11 18:38                 ` Linus Torvalds
2003-05-11 19:00                   ` Matt Mackall
2003-05-11 19:16                     ` Eric W. Biederman
2003-05-12  1:07                     ` H. Peter Anvin
2003-05-11 19:10                   ` Eric W. Biederman
2003-05-11 18:43                 ` Christer Weinigel
2003-05-11 20:22                   ` wingel
2003-05-11 20:26                     ` Davide Libenzi
2003-05-11 17:54         ` Eric W. Biederman
2003-05-13 12:49 Chuck Ebbert
2003-05-13 18:45 ` H. Peter Anvin
2003-05-13 19:04   ` Richard B. Johnson
2003-05-13 19:27     ` H. Peter Anvin

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