Dan Williams <dan.j.williams@xxxxxxxxx> writes: > [ adding Jeff directly since he has also been looking at > infrastructure to track when MAP_SYNC should be disabled ] > > On Wed, Apr 25, 2018 at 7:21 AM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote: >> On Wed, Apr 25, 2018 at 4:24 AM, Pankaj Gupta <pagupta@xxxxxxxxxx> wrote: >>> This patch adds virtio-pmem driver for KVM >>> guest. >> >> Minor nit, please expand your changelog line wrapping to 72 columns. >> >>> >>> Guest reads the persistent memory range >>> information from Qemu over VIRTIO and registers >>> it on nvdimm_bus. It also creates a nd_region >>> object with the persistent memory range >>> information so that existing 'nvdimm/pmem' >>> driver can reserve this into system memory map. >>> This way 'virtio-pmem' driver uses existing >>> functionality of pmem driver to register persistent >>> memory compatible for DAX capable filesystems. >> >> We need some additional enabling to disable MAP_SYNC for this enable to disable... I like it! ;-) >> configuration. In other words, if fsync() is required then we must >> disable the MAP_SYNC optimization. I think this should be a struct >> dax_device property looked up at mmap time in each MAP_SYNC capable >> ->mmap() file operation implementation. Ideally, qemu (seabios?) would advertise a platform capabilities sub-table that doesn't fill in the flush bits. -Jeff
