Re: [PATCH 0/4] Adding support to parse BERT for libnvdimm

[Dave Jiang <dave.jiang@intel.com>]

On 03/30/2018 09:45 AM, Kani, Toshi wrote:
> On Fri, 2018-03-30 at 09:38 -0700, Dan Williams wrote:
>> On Fri, Mar 30, 2018 at 8:04 AM, Kani, Toshi <toshi.kani@hpe.com> wrote:
>>> On Thu, 2018-03-29 at 15:37 -0700, Dave Jiang wrote:
>>>> The following series implements support for parsing of the BERT records
>>>> and adding the error memory ranges to nvdimm badblocks in order for the
>>>> kernel to avoid prevent the kernel from accessing those areas. And with
>>>> the addition of this support, we can surface the nd regions instead of waiting
>>>> for ARS to complete. So the ARS handling is reworked to run in the
>>>> background and not block nd region registration.
>>>
>>> Hi Dave,
>>>
>>> I agree on the problem, and adding an ability to obtain pmem badblocks
>>> records at boot-time without waiting for a new ARS scan to complete is a
>>> good option for users.
>>>
>>> However, I do not think using the BERT table is a good approach.  This
>>> requires FW to report pmem badblocks records with a new interface in
>>> addition to ARS records, which FW already implements for pmem.  ACPI 6.2
>>> defines Start ARS with Flags Bit[1] set to report badblocks record
>>> without starting a new ARS scan.  We set this bit after receiving a 0x81
>>> notification at this point.
>>>
>>> Can we use ARS with Flags bit[1] set at boot-time so that both OS and FW
>>> can use the same ARS implementation?
>>
>> You have a point.
>>
>> The other benefit I see to this policy is that it hopefully convinces
>> BIOS implementations to not run ARS at boot and leave it to the OS to
>> manage it in the background. If the platform has any critical errors
>> to report, i.e. ones that triggered a system reset, then it should be
>> able to report them in the flag-bit1 case.
> 
> Agreed.
> 
>> This also lets the implementation be completely self contained to the
>> nfit driver, and not grow any BERT entanglements that may or may not
>> be valid for the persistent memory case.
> 
> Right.  Thanks Dan!
> -Toshi
> 

Ok, I'll respin the series with what you suggested Toshi and drop the
BERT stuff.
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