Re: [PATCH v2 2/2] mce: acpi/apei: Add a boot option to disable ffmode for corrected errors

[Naveen N. Rao]

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@xxxxxxxxxxxxxxxxxx>
> > ---
> >   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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