On Tue, Oct 17, 2017 at 04:30:41AM -0400, Pankaj Gupta wrote: > > > > Are you saying do it as existing i.e ACPI pmem like interface? > > > The reason we have created this new driver is exiting pmem driver > > > does not define proper semantics for guest flushing requests. > > > > At this point I'm caring about the Linux-internal interface, and > > for that it should be integrated into the nvdimm subsystem and not > > a block driver. How the host <-> guest interface looks is a different > > idea. > > > > > > > > Regarding block support of driver, we want to achieve DAX support > > > to bypass guest page cache. Also, we want to utilize existing DAX > > > capable file-system interfaces(e.g fsync) from userspace file API's > > > to trigger the host side flush request. > > > > Well, if you want to support XFS+DAX better don't make it a block > > devices, because I'll post patches soon to stop using the block device > > entirely for the DAX case. > > o.k I will look at your patches once they are in mailing list. > Thanks for the heads up. > > If I am guessing it right, we don't need block device additional features > for pmem? We can bypass block device features like blk device cache flush etc. > Also, still we would be supporting ext4 & XFS filesystem with pmem? > > If there is time to your patches can you please elaborate on this a bit. I think the idea is that the nvdimm subsystem already adds block device semantics on top of the struct nvdimms that it manages. See drivers/nvdimm/blk.c. So it would be cleaner to make virtio-pmem an nvdimm bus. This will eliminate the duplication between your driver and drivers/nvdimm/ code. Try "git grep nvdimm_bus_register" to find drivers that use the nvdimm subsystem. The virtio-pmem driver could register itself similar to the existing ACPI NFIT and BIOS e820 pmem drivers. Stefan -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
