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From: Heiko Wundram <modelnine@modelnine.org>
To: xen-devel@lists.xensource.com
Subject: Re: Re: computer stalls instead of reboot
Date: Fri, 09 Sep 2011 15:52:10 +0200	[thread overview]
Message-ID: <4E6A1A0A.5040401@modelnine.org> (raw)
In-Reply-To: <j4d5ak$vrc$1@dough.gmane.org>

Am 09.09.2011 15:45, schrieb Sven Köhler:
> I wonder, what the disadvantage are.
> The hypervisor will still regulate CPU frequency, will it not?

No, it will not.

> Also, is the dom0 kernel doing something that it shouldn't do?
> (maybe something that collides with the ACPI-related activities of the
> hypervisor, if there are any?)

I guess the BIOS is simply reporting broken ACPI tables to the operating 
system (the board is a "consumer" board, so you can guess that the 
manufacturer only tests the ACPI-tables for compatability with Windows).

The ACPI tables (AFAIK, someone correct me) also contain a method for 
rebooting the system, which simply doesn't work/is broken when Xen is 
involved. Forcing acpi=off means that the normal triple-fault or 
kbd-controller reset machinery is always used, as ACPI isn't even 
initialized.

What struck me as odd, though: you can configure Linux to use "some 
other" form of hard reset through a kernel parameter, but setting that 
to explicitly use triple-faults didn't work, either (same hangs), so 
possibly it's some form of additional interaction between Xen, the board 
and the hypervisor. Anyway, the Hetzner "recommended" fix is just what I 
sent you, and I can confirm that works.

-- 
--- Heiko.

  reply	other threads:[~2011-09-09 13:52 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-09-08 23:15 computer stalls instead of reboot Sven Köhler
2011-09-08 23:17 ` Andrew Cooper
2011-09-08 23:40   ` Sven Köhler
2011-09-09 12:01     ` Andrew Cooper
2011-09-09 12:55       ` Sven Köhler
2011-09-09 13:31         ` Heiko Wundram
2011-09-09 13:45           ` Sven Köhler
2011-09-09 13:52             ` Heiko Wundram [this message]
2011-09-09 14:13               ` Sven Köhler
2011-09-11  0:55           ` Sven Köhler
2011-09-11  0:57       ` Sven Köhler

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