On Tue, Jun 23, 2015 at 3:19 AM, Christoph Hellwig <hch@xxxxxx> wrote: > On Mon, Jun 22, 2015 at 12:02:54PM -0700, Dan Williams wrote: >> I don't see the need to re-invent partitioning which is the path this >> requested rework is putting us on... >> >> However, when the need arises for smaller granularity BTT we can have >> the partition fight then. To be clear, I believe that need is already >> here today, but I'm not in a position to push that agenda at this late >> date. > > > Instead of all this complaining and moaning let's figure out what > architecture you'd actually want. The one I had in mind is: > > +------------------------------+ > | block layer (& partitions) | > +---------------+--------------+--------------------+ > | pmem driver | btt driver | other consumers | > +---------------+--------------+--------------------+ > | pmem API through libnvdimm | > +---------------------------------------------------+ > I've got this mostly coded up. The nice property is that BTTs now become another flavor of the same namespace. > If you really want btt to stack on top of pmem it really > needs to be moved out entirely of libnvdimm and be a > generic block driver just using ->rw_bytes, e.g.: > > > +------------------------------+ > | btt driver | > +------------------------------+ > | block layer (& partitions) | > +------------------------------+--------------------+ > | pmem driver | other consumers | > +------------------------------+--------------------+ > | pmem API through libnvdimm | > +---------------------------------------------------+ > > Not the current mess where btt pretends to be a stacking block > driver but still ties into libnvdimm. That tie was only to enable autodetect so that we don't need to run a BTT assembly step from an initramfs just to get an NVDIMM up and running. It was a convenience, not a requirement. > Add blk mode access to all the schemes, but it's really just > another next to the pmem driver each time. In fact while > looking over the code a bit more I start to wonder why > we need the blk driver at all - just hook into the nfit > do_io routines instead of the low-level API based on what > libnvdimm provides, and don't offer DAX for it. It mostly > seems duplicate code. Mostly, it does handle dis-contiguous dimm-physical-address ranges, but you're right we might be able to unify it in the coming cycle. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
