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

Andrey Borzenkov
2008-11-06T15:53:05Z

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On Thursday 06 November 2008, Ingo Molnar wrote:
>
> * Ingo Molnar <mingo@elte.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@redhat.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@mail.ru>
> Bisected-by: Andrey Borzenkov <arvidjaar@mail.ru>
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> Acked-by: Avi Kivity <avi@redhat.com>
> Signed-off-by: Ingo Molnar <mingo@elte.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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