On Thu, Apr 05, 2018 at 12:56:02AM -0700, Dan Williams wrote:
> Yes, I think it is unfortunate that the failure mode is exposed to
> software at all. The problem is that ADR is a platform feature that
> depends on power supply requirements external to the NVDIMM device. An
> SSD is different. It is a self contained system that can arrange for
> the whole device to fail if the internal energy source fails and
> otherwise hide this detail from software. My personal take, a system
> designer that can specify and qualify an entire stack of components
> can certainly opt-out of advertising the flush capability to the OS
> because, like the SSD vendor, they control the integrated solution. A
> platform vendor that allows off the shelf power supplies would in my
> opinion be remiss not to give the OS the option to mitigate the
> quality of some random power supply. It then follow that if the OS has
> the ability to mitigate ADR failure it should be through a common
> interface between fsdax and devdax.

That means IFF ADR can fail like this we can't treat it as stable
storage and we must not support MAP_SYNC or equivalent device dax
behavior, period.
Linux-nvdimm mailing list

Reply via email to