On Sun, Jan 22, 2017 at 06:39:28PM +0000, Matthew Wilcox wrote:
Two guests on the same physical machine (or a guest and a host) have
access to the same set of physical addresses. This might be an NV-DIMM, or it might just
be DRAM (for the purposes of reducing guest overhead). The network filesystem has been
enhanced with a call to allow the client to ask the server "What is the physical
address for this range of bytes in this file?"
We don't want to use the guest pagecache here. That's antithetical to the second
usage, and it's inefficient for the first usage.
And the answer is that you need a dax device for whatever memoery exposed
in this way, as it needs to show up in the memory map for example.