On Fri, 2017-11-03 at 14:21 +0800, Xiao Guangrong wrote: > On 11/03/2017 12:30 AM, Dan Williams wrote: > > > > Good point, I was assuming that the mmio flush interface would be > > discovered separately from the NFIT-defined memory range. Perhaps > > via > > PCI in the guest? This piece of the proposal needs a bit more > > thought... > > > > Consider the case that the vNVDIMM device on normal storage and > vNVDIMM device on real nvdimm hardware can both exist in VM, the > flush interface should be able to associate with the SPA region > respectively. That's why I'd like to integrate the flush interface > into NFIT/ACPI by using a separate table. Is it possible to be a > part of ACPI specification? :) It would also be perfectly fine to have the virtio PCI device indicate which vNVDIMM range it flushes. Since the guest OS needs to support that kind of device anyway, does it really matter which direction the device association points? We can go with the "best" interface for what could be a relatively slow flush (fsync on a file on ssd/disk on the host), which requires that the flushing task wait on completion asynchronously. If that kind of interface cannot be advertised through NFIT/ACPI, wouldn't it be perfectly fine to have only the virtio PCI device indicate which vNVDIMM range it flushes? -- All rights reversed
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