[PATCH v2] libnvdimm: Update persistence domain value for of_pmem and papr_scm device

Dan Williams dan.j.williams at intel.com
Tue Mar 24 12:21:27 AEDT 2020


On Fri, Mar 20, 2020 at 2:25 AM Aneesh Kumar K.V
<aneesh.kumar at linux.ibm.com> wrote:
>
>
> Hi Dan,
>
>
> Dan Williams <dan.j.williams at intel.com> writes:
>
> ...
>
>
> >
> >>
> >> Or are you suggesting that application should not infer any of those
> >> details looking at persistence_domain value? If so what is the purpose
> >> of exporting that attribute?
> >
> > The way the patch was worded I thought it was referring to an explicit
> > mechanism outside cpu cache flushes, i.e. a mechanism that required a
> > driver call.
> >
>
> This patch is blocked because I am not expressing the details correctly.
> I updates this as below. Can you suggest if this is ok? If not what
> alternate wording do you suggest to document "memory controller"
>
>
> commit 329b46e88f8cd30eee4776b0de7913ab4d496bd8
> Author: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
> Date:   Wed Dec 18 13:53:16 2019 +0530
>
>     libnvdimm: Update persistence domain value for of_pmem and papr_scm device
>
>     Currently, kernel shows the below values
>             "persistence_domain":"cpu_cache"
>             "persistence_domain":"memory_controller"
>             "persistence_domain":"unknown"
>
>     "cpu_cache" indicates no extra instructions is needed to ensure the persistence
>     of data in the pmem media on power failure.
>
>     "memory_controller" indicates cpu cache flush instructions is required to flush
>     the data. Platform provides mechanisms to automatically flush outstanding
>     write data from memory controler to pmem on system power loss.
>
>     Based on the above use memory_controller for non volatile regions on ppc64.

Looks good to me, want to resend via git-format-patch?


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