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SubjectRe: [PATCH v8 1/5] powerpc: Document details on H_SCM_HEALTH hcall
Date
Thanks for looking into this patchset Dan,


Dan Williams <dan.j.williams@intel.com> writes:

> On Tue, May 26, 2020 at 9:13 PM Vaibhav Jain <vaibhav@linux.ibm.com> wrote:
>>
>> Add documentation to 'papr_hcalls.rst' describing the bitmap flags
>> that are returned from H_SCM_HEALTH hcall as per the PAPR-SCM
>> specification.
>>
>
> Please do a global s/SCM/PMEM/ or s/SCM/NVDIMM/. It's unfortunate that
> we already have 2 ways to describe persistent memory devices, let's
> not perpetuate a third so that "grep" has a chance to find
> interrelated code across architectures. Other than that this looks
> good to me.

Sure, will use PAPR_NVDIMM instead of PAPR_SCM for new code being
introduced. However certain identifiers like H_SCM_HEALTH are taken from
the papr specificiation hence need to use the same name.

>
>> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
>> Cc: Dan Williams <dan.j.williams@intel.com>
>> Cc: Michael Ellerman <mpe@ellerman.id.au>
>> Cc: Ira Weiny <ira.weiny@intel.com>
>> Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
>> ---
>> Changelog:
>> v7..v8:
>> * Added a clarification on bit-ordering of Health Bitmap
>>
>> Resend:
>> * None
>>
>> v6..v7:
>> * None
>>
>> v5..v6:
>> * New patch in the series
>> ---
>> Documentation/powerpc/papr_hcalls.rst | 45 ++++++++++++++++++++++++---
>> 1 file changed, 41 insertions(+), 4 deletions(-)
>>
>> diff --git a/Documentation/powerpc/papr_hcalls.rst b/Documentation/powerpc/papr_hcalls.rst
>> index 3493631a60f8..45063f305813 100644
>> --- a/Documentation/powerpc/papr_hcalls.rst
>> +++ b/Documentation/powerpc/papr_hcalls.rst
>> @@ -220,13 +220,50 @@ from the LPAR memory.
>> **H_SCM_HEALTH**
>>
>> | Input: drcIndex
>> -| Out: *health-bitmap, health-bit-valid-bitmap*
>> +| Out: *health-bitmap (r4), health-bit-valid-bitmap (r5)*
>> | Return Value: *H_Success, H_Parameter, H_Hardware*
>>
>> Given a DRC Index return the info on predictive failure and overall health of
>> -the NVDIMM. The asserted bits in the health-bitmap indicate a single predictive
>> -failure and health-bit-valid-bitmap indicate which bits in health-bitmap are
>> -valid.
>> +the NVDIMM. The asserted bits in the health-bitmap indicate one or more states
>> +(described in table below) of the NVDIMM and health-bit-valid-bitmap indicate
>> +which bits in health-bitmap are valid. The bits are reported in
>> +reverse bit ordering for example a value of 0xC400000000000000
>> +indicates bits 0, 1, and 5 are valid.
>> +
>> +Health Bitmap Flags:
>> +
>> ++------+-----------------------------------------------------------------------+
>> +| Bit | Definition |
>> ++======+=======================================================================+
>> +| 00 | SCM device is unable to persist memory contents. |
>> +| | If the system is powered down, nothing will be saved. |
>> ++------+-----------------------------------------------------------------------+
>> +| 01 | SCM device failed to persist memory contents. Either contents were not|
>> +| | saved successfully on power down or were not restored properly on |
>> +| | power up. |
>> ++------+-----------------------------------------------------------------------+
>> +| 02 | SCM device contents are persisted from previous IPL. The data from |
>> +| | the last boot were successfully restored. |
>> ++------+-----------------------------------------------------------------------+
>> +| 03 | SCM device contents are not persisted from previous IPL. There was no |
>> +| | data to restore from the last boot. |
>> ++------+-----------------------------------------------------------------------+
>> +| 04 | SCM device memory life remaining is critically low |
>> ++------+-----------------------------------------------------------------------+
>> +| 05 | SCM device will be garded off next IPL due to failure |
>> ++------+-----------------------------------------------------------------------+
>> +| 06 | SCM contents cannot persist due to current platform health status. A |
>> +| | hardware failure may prevent data from being saved or restored. |
>> ++------+-----------------------------------------------------------------------+
>> +| 07 | SCM device is unable to persist memory contents in certain conditions |
>> ++------+-----------------------------------------------------------------------+
>> +| 08 | SCM device is encrypted |
>> ++------+-----------------------------------------------------------------------+
>> +| 09 | SCM device has successfully completed a requested erase or secure |
>> +| | erase procedure. |
>> ++------+-----------------------------------------------------------------------+
>> +|10:63 | Reserved / Unused |
>> ++------+-----------------------------------------------------------------------+
>>
>> **H_SCM_PERFORMANCE_STATS**
>>
>> --
>> 2.26.2
>>

--
Cheers
~ Vaibhav

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