[dm-devel] Persistent memory interface

[Mikulas Patocka]

On Fri, 19 Jun 2015, Dan Williams wrote:

> On Fri, Jun 19, 2015 at 9:33 AM, Mikulas Patocka <mpatocka at redhat.com> wrote:
> > Hi
> >
> > I looked at the new the persistent memory block device driver
> > (drivers/block/pmem.c and arch/x86/kernel/pmem.c) and it seems that the
> > interface between them is incorrect.
> >
> > If I want to use persistent memory in another driver, for a different
> > purpose, how can I make sure that that drivers/block/pmem.c doesn't attach
> > to this piece of memory and export it? It seems not possible.
> > drivers/block/pmem.c attaches to everything without regard that there may
> > be other users of persistent memory.
> 
> Simply partition the pmem device however you see fit and then
> blkdev_get_by_path(<dev>, FMODE_EXCL, <holder>) the resulting
> partition(s).

But that still means accessing it through the block layer.

I need to access persistent memory directly - map it into the kernel space 
and access it as mapped memory - and if I do it, it will fight with 
drivers/block/pmem.c over ownership of the memory :-(

Mikulas