Re: Enabling peer to peer device transactions for PCIe devices

Christoph Hellwig
2016-12-05T20:06:32Z

On Mon, Dec 05, 2016 at 12:46:14PM -0700, Jason Gunthorpe wrote:
> In any event the allocator still needs to track which regions are in
> use and be able to hook 'free' from userspace. That does suggest it
> should be integrated into the nvme driver and not a bolt on driver..

Two totally different use cases:

- a card that exposes directly byte addressable storage as a PCI-e
bar. Thin of it as a nvdimm on a PCI-e card. That's the iopmem
case.
- the NVMe CMB which exposes a byte addressable indirection buffer for
I/O, but does not actually provide byte addressable persistent
storage. This is something that needs to be added to the NVMe driver
(and the block layer for the abstraction probably).