Messages in this thread | | | Date | Wed, 15 Jun 2022 08:01:50 -0700 | From | Ira Weiny <> | Subject | Re: [PATCH 2/3] cxl/mbox: Add GET_POISON_LIST mailbox command support |
| |
On Tue, Jun 14, 2022 at 10:07:52PM -0700, Alison Schofield wrote: > On Tue, Jun 14, 2022 at 08:22:41PM -0700, Ira Weiny wrote: >
[snip]
> > > + > > > + do { > > > + rc = cxl_mbox_send_cmd(cxlds, CXL_MBOX_OP_GET_POISON, &pi, > > > + sizeof(pi), po, cxlds->payload_size); > > > + if (rc) > > > + goto out; > > > + > > > + if (po->flags & CXL_POISON_FLAG_OVERFLOW) { > > > + time64_t o_time = le64_to_cpu(po->overflow_timestamp); > > > + > > > + dev_err(dev, "Poison list overflow at %ptTs UTC\n", > > > + &o_time); > > > + rc = -ENXIO; > > > + goto out; > > > > I guess the idea is that this return will trigger something else will clear the list, > > rebuild the list, and perform a scan media request? > > > Per CXL Spec 8.2.9.5.4.1: The poison list may be incomplete when the list > has overflowed. User can perform a Scan Media to try to clear and rebuild > the list, with no guarantee that the overflow will not recur. > > So yes to what you are saying. This return value should indicate to > user space that a Scan Media should be issued. Issuing the Scan Media > to the device does lead the device to rebuild it's list, as you say. > Also, when we get the Scan Media results, the device is able to report > partial results and tell the host to collect the error records, and > then restart the scan, get results again, and on and on until the scan > is complete. > > Perhaps a clarification - there is not a logical pairing of Scan Media > followed by Get Poison List. Scan Media followed by Get Scan Media > Results is the logical pairing. Get Poison List is getting a snapshot > of the poison list at a point in time. The device adds DPAs to the list > when the device detects poison, some devices run their own backround > scans and add to the poison list, and then there are the user initiated > actions (Scan Media and Poison Inject) that can affect the list. > > > I'm just wondering if this loop should continue to clear the list and then let > > something else do the scan media request? > > It's not like the _MORE status where the device is telling the host to > come back and gather more. I think the action of failing, and letting > user initiated a Scan Media is correct course here.
Fair enough. But I guess I'm still confused by the spec. The way I read it yesterday (and I could be wrong) was that the OS was supposed to read the entries to clear the list? Is that not true?
I the device will clear the list internally when Scan Media is run?
At this point I'm just trying to understand not necessarily objecting to the patch.
Ira
> > So, this response got kind of long winded. As you can see, especially > if one looks in the spec as I know you are, there are additional > commands that need to be implemented to complete the ARS feature set. > And, of course, we'll offer user space tooling (NDCTL and libcxl). >
| |