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: <51C37251.4000008@linux.vnet.ibm.com>
Date:	Fri, 21 Jun 2013 02:51:21 +0530
From:	"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To:	"Luck, Tony" <tony.luck@...el.com>
CC:	Borislav Petkov <bp@...en8.de>,
	"ananth@...ibm.com" <ananth@...ibm.com>,
	"masbock@...ux.vnet.ibm.com" <masbock@...ux.vnet.ibm.com>,
	"lcm@...ux.vnet.ibm.com" <lcm@...ux.vnet.ibm.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"Huang, Ying" <ying.huang@...el.com>,
	Robert Richter <rric@...nel.org>
Subject: Re: [PATCH v2 2/2] mce: acpi/apei: Add a boot option to disable ff
 mode for corrected errors

On 06/20/2013 02:58 AM, Luck, Tony wrote:
>> Ok, where is that semantics? What in a CPER record does say "this error
>> should tell you that you need to offline the containing page and I'm
>> telling you this exactly only once"? Error Severity 0, i.e. Recoverable?
>
> Naveen - this one is for you (or for your BIOS team).  Can you get us a sample
> CPER that you plan to provide when the BIOS decides that its threshold has
> been exceeded?  How will it be different from what old WSM-EX platforms
> were sending to us?  Hopefully the answer is encoded in the CPER record
> and not in some code we have to put in Linux to say "if (IBMplatform) do_thing_1(); else ... "

Looking at the specs, there might be a few ways we can do this:
- One, Error threshold value of 1 in the Hardware Error Notification 
structure of CMC. This field is described as the number of error events 
before OS considers this as an error event. With a threshold value of 1, 
we are essentially asking the OS not to threshold further.
- Two, the Generic Error Data Entry (aka UEFI Section Descriptor) has a 
flag which indicates 'Error Threshold Exceeded'. From the UEFI spec, it 
looks like we could consider this as an indication to offline the page; 
though I am not sure if/how this relates to the threshold value above.

Thoughts?


Thanks,
Naveen

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