Re: [RFC PATCH v1 0/6] use mm to manage NVDIMM (pmem) zone

[Matthew Wilcox]

On Mon, May 07, 2018 at 11:57:10AM -0700, Dan Williams wrote:
> I think adding yet one more mm-zone is the wrong direction. Instead,
> what we have been considering is a mechanism to allow a device-dax
> instance to be given back to the kernel as a distinct numa node
> managed by the VM. It seems it times to dust off those patches.

I was wondering how "safe" we think that ability is.  NV-DIMM pages
(obviously) differ from normal pages by their non-volatility.  Do we
want their contents from the previous boot to be observable?  If not,
then we need the BIOS to clear them at boot-up, which means we would
want no kernel changes at all; rather the BIOS should just describe
those pages as if they were DRAM (after zeroing them).