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

["Kani, Toshi" <toshi.kani-ZPxbGqLxI0U@public.gmane.org>]

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?

Thanks,
-Toshi