[dm-devel] [PATCH] vmalloc: introduce vmap_pfn for persistent memory

[Dan Williams]

On Wed, Nov 8, 2017 at 12:15 PM, Mikulas Patocka <mpatocka at redhat.com> wrote:
>
>
> On Wed, 8 Nov 2017, Dan Williams wrote:
>
>> On Wed, Nov 8, 2017 at 7:35 AM, Christoph Hellwig <hch at infradead.org> wrote:
>> > On Wed, Nov 08, 2017 at 10:21:38AM -0500, Mikulas Patocka wrote:
>> >> > And what do you do for an architecture with virtuall indexed caches?
>> >>
>> >> Persistent memory is not supported on such architectures - it is only
>> >> supported on x86-64 and arm64.
>> >
>> > For now.  But once support is added your driver will just corrupt data
>> > unless you have the right API in place.
>>
>> I'm also in the process of ripping out page-less dax support. With
>> pages we can potentially leverage the VIVT-cache support in some
>> architectures, likely with more supporting infrastructure for
>> dax_flush().
>
> Should I remove all the code for page-less persistent memory from my
> driver?
>

Yes, that would be my recommendation. You can see that filesystem-dax
is on its way to dropping page-less support in this series:

   https://lists.01.org/pipermail/linux-nvdimm/2017-October/013125.html