On Thu, Aug 24, 2017 at 09:31:17AM -0700, Dan Williams wrote: > External agent is a DMA device, or a hypervisor like Xen. In the DMA > case perhaps we can use the fcntl lease mechanism, I'll investigate. > In the Xen case it actually would need to use fiemap() to discover the > physical addresses that back the file to setup their M2P tables. > Here's the discussion where we discovered that physical address > dependency: > > https://lists.xen.org/archives/html/xen-devel/2017-04/msg00419.html fiemap does not work to discover physical addresses. If they want to do anything involving physical address they will need a kernel driver.
