On Wed, Jun 23, 2021 at 03:19:11PM +0800, Coly Li wrote:

Bcache does not support endian clean indeed,

Then we need to fix that eventually rather than making it worse.  Which
means any _new_ data structure should start that way.

and libnvdimm only works with
64bit physical address width.

Maybe it does right now.  But ther is nothing fundamental in that, so
please don't design stupid on-disk formats to encode that are going to
come back to bite us sooner or later.  Be that by adding 32-bit support
for any Linux DAX device, or by new 96 or 128bit CPUs.

The only restriction here by using pointer is
the CPU register word should be 64bits, because we use the NVDIMM as memory.

Is it one of the way how NVDIMM (especially Intel AEP) designed to use ?
As a non-volatiled memory.

Not for on-disk data structures.

Does the already mapped DAX base address change in runtime during memory
hot plugable ?
If not, it won't be a problem here for this specific use case.

It could change between one use and another.