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Re: [PATCH 1/6] pmem: remove indirection layer arch_has_pmem_api()

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On Thu, Aug 6, 2015 at 10:43 AM, Ross Zwisler
<ross.zwisler@linux.intel.com> wrote:
> Prior to this change arch_has_wmb_pmem() was only called by
> arch_has_pmem_api().  Both arch_has_wmb_pmem() and arch_has_pmem_api()
> checked to make sure that CONFIG_ARCH_HAS_PMEM_API was enabled.
>
> Instead, remove one extra layer of indirection and the redundant
> CONFIG_ARCH_HAS_PMEM_API check, and just have arch_has_pmem_api()
> call __arch_has_wmb_pmem() directly.

So I think this patch takes us further away from where we want to go
in the near term which is a finer grained pmem api.  The class of
systems where (has_pmem_api() && !has_wmb_pmem()) is existing energy
backed nvdimm platforms.  I'm assuming those platforms will want to
assert persistence guarantees in the absence of a pcommit-like
instruction, and that we want to stop gating arch_has_pmem_api() on
the presence of wmb_pmem() capability.  In that case
arch_has_wmb_pmem() will be useful to have and that was the original
intent for including it, that intent did not seem to comprehended in
the changelog.
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[PATCH 0/6] pmem, dax: I/O path enhancements Ross Zwisler <ross.zwisler@linux.intel.com> - 2015-08-06 19:50 +0200
  [PATCH 4/6] pmem: Add wb_cache_pmem() and flush_cache_pmem() Ross Zwisler <ross.zwisler@linux.intel.com> - 2015-08-06 19:50 +0200
  [PATCH 5/6] nd_blk: add support for "read flush" DSM flag Ross Zwisler <ross.zwisler@linux.intel.com> - 2015-08-06 19:50 +0200
  [PATCH 2/6] x86: clean up conditional pmem includes Ross Zwisler <ross.zwisler@linux.intel.com> - 2015-08-06 19:50 +0200
    Re: [PATCH 2/6] x86: clean up conditional pmem includes Christoph Hellwig <hch@infradead.org> - 2015-08-07 08:40 +0200
      Re: [PATCH 2/6] x86: clean up conditional pmem includes Ross Zwisler <ross.zwisler@linux.intel.com> - 2015-08-07 16:10 +0200
  [PATCH 6/6] dax: update I/O path to do proper PMEM flushing Ross Zwisler <ross.zwisler@linux.intel.com> - 2015-08-06 19:50 +0200
    Re: [PATCH 6/6] dax: update I/O path to do proper PMEM flushing Dave Chinner <david@fromorbit.com> - 2015-08-06 23:10 +0200
      Re: [PATCH 6/6] dax: update I/O path to do proper PMEM flushing Ross Zwisler <ross.zwisler@linux.intel.com> - 2015-08-07 21:10 +0200
    Re: [PATCH 6/6] dax: update I/O path to do proper PMEM flushing Dan Williams <dan.j.williams@intel.com> - 2015-08-06 23:30 +0200
  [PATCH 1/6] pmem: remove indirection layer arch_has_pmem_api() Ross Zwisler <ross.zwisler@linux.intel.com> - 2015-08-06 19:50 +0200
    Re: [PATCH 1/6] pmem: remove indirection layer arch_has_pmem_api() Christoph Hellwig <hch@infradead.org> - 2015-08-07 08:40 +0200
      Re: [PATCH 1/6] pmem: remove indirection layer arch_has_pmem_api() Ross Zwisler <ross.zwisler@linux.intel.com> - 2015-08-07 16:10 +0200
    Re: [PATCH 1/6] pmem: remove indirection layer arch_has_pmem_api() Dan Williams <dan.j.williams@intel.com> - 2015-08-07 18:20 +0200
      Re: [PATCH 1/6] pmem: remove indirection layer arch_has_pmem_api() Ross Zwisler <ross.zwisler@linux.intel.com> - 2015-08-07 20:50 +0200
        Re: [PATCH 1/6] pmem: remove indirection layer arch_has_pmem_api() Dan Williams <dan.j.williams@intel.com> - 2015-08-07 22:10 +0200
  Re: [PATCH 0/6] pmem, dax: I/O path enhancements Dan Williams <dan.j.williams@intel.com> - 2015-08-07 18:50 +0200
    Re: [PATCH 0/6] pmem, dax: I/O path enhancements Ross Zwisler <ross.zwisler@linux.intel.com> - 2015-08-07 21:10 +0200

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