linux-kernel - Re: [PATCH v2 2/2] mce: acpi/apei: Add a boot option to disable ff mode for corrected errors

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Message-ID: <51C1F5CB.9020005@linux.vnet.ibm.com>
Date:	Wed, 19 Jun 2013 23:47:47 +0530
From:	"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To:	Borislav Petkov <bp@...en8.de>
CC:	tony.luck@...el.com, ananth@...ibm.com, masbock@...ux.vnet.ibm.com,
	lcm@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org,
	linux-acpi@...r.kernel.org, ying.huang@...el.com
Subject: Re: [PATCH v2 2/2] mce: acpi/apei: Add a boot option to disable ff
 mode for corrected errors

On 06/19/2013 11:34 PM, Borislav Petkov wrote:
> On Wed, Jun 19, 2013 at 11:27:42PM +0530, Naveen N. Rao wrote:
>> Add a boot option to disable firmware first mode for corrected errors.
>>
>> Signed-off-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
>> ---
>>   Documentation/x86/x86_64/boot-options.txt |    5 +++++
>>   arch/x86/include/asm/acpi.h               |    2 ++
>>   arch/x86/kernel/acpi/boot.c               |    5 +++++
>>   drivers/acpi/apei/hest.c                  |    3 ++-
>>   4 files changed, 14 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/x86/x86_64/boot-options.txt b/Documentation/x86/x86_64/boot-options.txt
>> index e9e8ddb..1228b22 100644
>> --- a/Documentation/x86/x86_64/boot-options.txt
>> +++ b/Documentation/x86/x86_64/boot-options.txt
>> @@ -176,6 +176,11 @@ ACPI
>>
>>     acpi=noirq	Don't route interrupts
>>
>> +  acpi=nocmcff	Disable firmware first mode for corrected errors. This
>> +		disables parsing the HEST CMC error source to check if
>> +		firmware has set the FF flag. This may result in
>> +		duplicate corrected error reports.
>
> Interesting, why? Why would we even need such an option? My impression
> is, if ACPI tells us FF, MCE code doesn't poll those banks anymore. So
> where do the duplicated reports come from?

This option is a way to revert to the existing behavior where we 
continue to enable CMCI/poll. If we enable this option, then we will 
receive error events from CMCI/polling as well as from the firmware 
through GHES.


Thanks,
Naveen

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