Re: [PATCH v4 2/4] generic: test mmap io fom DAX to non-DAX

Jeff Moyer
2017-07-28T14:55:35Z

Christoph Hellwig <hch@infradead.org> writes:

> On Mon, Apr 17, 2017 at 03:14:13PM +0800, Xiong Zhou wrote:
>> Mount TEST_DEV as non-DAX, SCRATCH_DEV as DAX, then
>> do mmap DIO from DAX to non-DAX.
>>
>> This test is split from generic/413. Since DIO from DAX
>> to non-DAX is only supported/doable when device underneath
>> has memory(struct page) backend.
>>
>> By ndctl looking at SCRATCH_DEV, skip this test if it is
>> not in "memory mode".
>
> DAX devices don't need to be something using NFIT, so I don't think this
> method is correct.

Memory mode does not depend on an NFIT. There's a superblock stored in
the persistent memory that tracks its mode when labels are not present.

-Jeff