linux-kernel - Re: 2.6.19-rc[1-4]: boot fail with (lapic && on

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Date:	Tue, 14 Nov 2006 01:59:59 -0500
From:	Len Brown <len.brown@...el.com>
To:	earny@...4u.de
Cc:	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org
Subject: Re: 2.6.19-rc[1-4]: boot fail with (lapic && on_battery)

On Tuesday 31 October 2006 16:27, Ernst Herzberg wrote:

> With 2.6.18.x everything works fine.
> 
> But 2.16.19-rc does not boot if the laptop runs on battery _and_ lapic is 
> defined as boot parameter.

> Local APIC disabled by BIOS -- you can enable it with "lapic"

The BIOS is advising you here that it is a bad idea to enable the LAPIC on this system.
So why are you using the "lapic" boot parameter?

If you are running an CONFIG_SMP kernel with LAPIC enabled and deep C-states
(such as are available on Thinkpads when on battery mode), you will
run into the following bug:

http://bugzilla.kernel.org/show_bug.cgi?id=7376

As this is not new, the mystery is really why you see no problems in 2.6.18.
Perhaps you can forward the contents of /proc/interrupts for 2.6.18 with "lapic"
and we can see if the timer and the LOC are in sync or not when on battery?
/proc/acpi/processor/*/power will also tell us about the C-states --
dump it for both AC and battery mode.

thanks,
-Len
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