On Fri, 2019-01-25 at 09:18 -0800, Dan Williams wrote: > On Fri, Jan 25, 2019 at 12:20 AM Du, Fan <fan.du@xxxxxxxxx> wrote: > > Dan > > > > Thanks for the insights! > > > > Can I say, the UCE is delivered from h/w to OS in a single way in > > case of machine > > check, only PMEM/DAX stuff filter out UC address and managed in its > > own way by > > badblocks, if PMEM/DAX doesn't do so, then common RAS workflow will > > kick in, > > right? > > The common RAS workflow always kicks in, it's just the page state > presented by a DAX mapping needs distinct handling. Once it is > hot-plugged it no longer needs to be treated differently than "System > RAM". > > > And how about when ARS is involved but no machine check fired for > > the function > > of this patchset? > > The hotplug effectively disconnects this address range from the ARS > results. They will still be reported in the libnvdimm "region" level > badblocks instance, but there's no safe / coordinated way to go clear > those errors without additional kernel enabling. There is no "clear > error" semantic for "System RAM". > Perhaps as future enabling, the kernel can go perform "clear error" for offlined pages, and make them usable again. But I'm not sure how prepared mm is to re-accept pages previously offlined.
