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From: Dan Williams <dan.j.williams@intel.com>
To: "Kani, Toshi" <toshi.kani@hpe.com>
Cc: "Luck, Tony" <tony.luck@intel.com>,
	"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
	"rjw@rjwysocki.net" <rjw@rjwysocki.net>,
	"linux-acpi@vger.kernel.org" <linux-acpi@vger.kernel.org>,
	"lenb@kernel.org" <lenb@kernel.org>
Subject: Re: [PATCH 0/4] Adding support to parse BERT for libnvdimm
Date: Fri, 30 Mar 2018 09:38:48 -0700	[thread overview]
Message-ID: <CAPcyv4iBnOLrFyhZBpAhkrdkY42w7g125jQhxi2Qv6drC7HQdA@mail.gmail.com> (raw)
In-Reply-To: <1522422276.2693.268.camel@hpe.com>

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.

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.
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  reply	other threads:[~2018-03-30 16:38 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-29 22:37 [PATCH 0/4] Adding support to parse BERT for libnvdimm Dave Jiang
2018-03-29 22:37 ` [PATCH 1/4] acpi: add find error record in BERT function Dave Jiang
2018-03-30 23:36   ` kbuild test robot
2018-03-29 22:37 ` [PATCH 2/4] acpi/libnvdimm: search through BERT records and add to nvdimm badblocks Dave Jiang
2018-03-29 22:37 ` [PATCH 3/4] acpi/nfit: removing ARS timeout and change scrubbing to delayed work Dave Jiang
2018-03-29 22:37 ` [PATCH 4/4] acpi/nfit: allow knob to disable ARS being issued at kernel boot Dave Jiang
2018-03-30 15:04 ` [PATCH 0/4] Adding support to parse BERT for libnvdimm Kani, Toshi
2018-03-30 16:38   ` Dan Williams [this message]
2018-03-30 16:45     ` Kani, Toshi
2018-03-30 16:49       ` Dave Jiang
2018-03-30 16:51         ` Kani, Toshi

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