linux-kernel - Re: [PATCH 15/15] Revert "x86: default to reboot via ACPI"

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Message-Id: <200811061853.08003.arvidjaar@mail.ru>
Date:	Thu, 6 Nov 2008 18:53:05 +0300
From:	Andrey Borzenkov <arvidjaar@...l.ru>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Eduardo Habkost <ehabkost@...hat.com>, Avi Kivity <avi@...hat.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Andrew Morton <akpm@...l.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>, kexec@...ts.infradead.org,
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 15/15] Revert "x86: default to reboot via ACPI"

[I had to trim direct recipients as my provider would refuse deliver
claiming it is spam]

On Thursday 06 November 2008, Ingo Molnar wrote:
> 
> * Ingo Molnar <mingo@...e.hu> wrote:
> 
> > > Andrey Borzenkov's patch, for example, adds a new DMI entry 
> > > because reboot=acpi breaks his keyboard (even without KVM, I 
> > > guess). Andrey, was that the case?
> > 
> > hm, IIRC the problem was KVM in his case too.
> 
> actually, Andrey's problem seems to be unrelated. So i've queued up 
> the revert below in tip/x86/urgent for v2.6.28. Thanks guys!
> 

Yes, I do not use KVM. Actually my CPU (PIII) does not even support
virtualization.

> 	Ingo
> 
> ---------------->
> From 8d00450d296dedec9ada38d43b83e79cca6fd5a3 Mon Sep 17 00:00:00 2001
> From: Eduardo Habkost <ehabkost@...hat.com>
> Date: Tue, 4 Nov 2008 12:52:44 -0200
> Subject: [PATCH] Revert "x86: default to reboot via ACPI"
> 
> This reverts commit c7ffa6c26277b403920e2255d10df849bd613380.
> 
> the assumptio of this change was that this would not break
> any existing machine. Andrey Borzenkov reported troubles with
> the ACPI reboot method: the system would hang on reboot, necessiating
> a power cycle. Probably more systems are affected as well.
> 

To be precise - system reboots but keyboard is non-functional after that.
Power off is required to clear this condition.

I am fine with either way (revert or DMI). But if problem which ACPI
reboot fixed (or worked around) is not solved differently I think
reverting to old way is better.

> Also, there are patches queued up for v2.6.29 to disable virtualization
> on emergency_restart() - which was the original motivation of
> this change.
> 
> Reported-by: Andrey Borzenkov <arvidjaar@...l.ru>
> Bisected-by: Andrey Borzenkov <arvidjaar@...l.ru>
> Signed-off-by: Eduardo Habkost <ehabkost@...hat.com>
> Acked-by: Avi Kivity <avi@...hat.com>
> Signed-off-by: Ingo Molnar <mingo@...e.hu>
> ---
>  arch/x86/kernel/reboot.c |    6 +-----
>  1 files changed, 1 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
> index f4c93f1..724adfc 100644
> --- a/arch/x86/kernel/reboot.c
> +++ b/arch/x86/kernel/reboot.c
> @@ -29,11 +29,7 @@ EXPORT_SYMBOL(pm_power_off);
>  
>  static const struct desc_ptr no_idt = {};
>  static int reboot_mode;
> -/*
> - * Keyboard reset and triple fault may result in INIT, not RESET, which
> - * doesn't work when we're in vmx root mode.  Try ACPI first.
> - */
> -enum reboot_type reboot_type = BOOT_ACPI;
> +enum reboot_type reboot_type = BOOT_KBD;
>  int reboot_force;
>  
>  #if defined(CONFIG_X86_32) && defined(CONFIG_SMP)
> 
> 



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