From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1756000AbbJHLoE (ORCPT <rfc822;w@1wt.eu>);
	Thu, 8 Oct 2015 07:44:04 -0400
Received: from mail-pa0-f42.google.com ([209.85.220.42]:35237 "EHLO
	mail-pa0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1753416AbbJHLoA (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Thu, 8 Oct 2015 07:44:00 -0400
Message-ID: <56165701.90402@linaro.org>
Date: Thu, 08 Oct 2015 19:44:01 +0800
From: Hanjun Guo <hanjun.guo@linaro.org>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0
MIME-Version: 1.0
To: kernel test robot <ying.huang@linux.intel.com>,
        Al Stone <al.stone@linaro.org>
CC: lkp@01.org, LKML <linux-kernel@vger.kernel.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Subject: Re: [lkp] [ACPI] 7494b07eba: Kernel panic - not syncing: Watchdog
 detected hard LOCKUP on cpu 0
References: <871td6xcxc.fsf@yhuang-dev.intel.com>
In-Reply-To: <871td6xcxc.fsf@yhuang-dev.intel.com>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 10/08/2015 11:21 AM, kernel test robot wrote:
> FYI, we noticed the below changes on
>
> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> commit 7494b07ebaae2117629024369365f7be7adc16c3 ("ACPI: add in a bad_madt_entry() function to eventually replace the macro")
>
> [    0.000000] ACPI: undefined MADT subtable type for FADT 4.0: 127 (length 12)

Seems that the MADT table contains reserved subtable type (0x7F),
so this is traded as a wrong type in our patch.

> [    0.000000] ACPI: Error parsing LAPIC address override entry

This was called by early_acpi_parse_madt_lapic_addr_ovr() in
arch/x86/kernel/acpi/boot.c, which is scanning MADT for the first
time when booting, so it will fail the boot process when finding
the reserved MADT subtable type.

> [    0.000000] ACPI: Invalid BIOS MADT, disabling ACPI

As the spec said in Table 5-46 (ACPI 6.0):

0x10-0x7F Reserved. OSPM skips structures of the reserved type.

Should we just ignore those reserved type when scanning the MADT
table? In the patch "ACPI: add in a bad_madt_entry() function to
eventually replace the macro", we just trade it as wrong, that's
why we failed to boot the system.

Thanks
Hanjun