linux-kernel - Re: [PATCH] Add support of NVDIMM memory error notification in ACPI 6.2

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Date:   Thu, 8 Jun 2017 17:38:21 +0000
From:   "Kani, Toshimitsu" <toshi.kani@....com>
To:     "dan.j.williams@...el.com" <dan.j.williams@...el.com>,
        "Knippers, Linda" <linda.knippers@....com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "rjw@...ysocki.net" <rjw@...ysocki.net>,
        "vishal.l.verma@...el.com" <vishal.l.verma@...el.com>
Subject: Re: [PATCH] Add support of NVDIMM memory error notification in ACPI
 6.2

On Thu, 2017-06-08 at 10:34 -0700, Dan Williams wrote:
> On Thu, Jun 8, 2017 at 10:30 AM, Linda Knippers <linda.knippers@....c
> om> wrote:
> [..]
> > Wasn't Dan concerned about how the OS can know whether the FW
> > supports that bit in the Start ARS?
> > 
> > The Query ARS Capabilities DSM has a bit that tells the OS whether
> > the platform supports the notification and the point of the
> > notification was to tell the OS it could do a Start ARS with bit 1
> > set.  Of course, if you get the notification then that means the
> > platform has the capability to deliver it, but it might not hurt to
> > check the flag from the Query Capabilities bit.
> 
> Good point, yes, I think it is safe to assume that a BIOS that claims
> to support un-correctable error notification also supports this Start
> ARS flag.

Yes, ACPI 6.2, section 9.20.7.2, defines that:

      Upon receiving the notification, the OSPM may decide to issue
      a Start ARS with Flags Bit [1] set to prepare for the retrieval
      of existing records and issue the Query ARS Status function to
      retrieve the records.

So, I believe it is safe to assume that BIOS supporting 0x81 also
supports flags Big [1].  Sorry, this is what I should have said in my
previous email...

Thanks,
-Toshi