Messages in this thread | | | Subject | Re: [Linux-nvdimm] [PATCH 04/21] nd: create an 'nd_bus' from an 'nfit_desc' | From | Toshi Kani <> | Date | Wed, 22 Apr 2015 13:38:58 -0600 |
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On Wed, 2015-04-22 at 12:28 -0700, Dan Williams wrote: > On Wed, Apr 22, 2015 at 11:23 AM, Toshi Kani <toshi.kani@hp.com> wrote: > > On Wed, 2015-04-22 at 11:20 -0700, Dan Williams wrote: > >> On Wed, Apr 22, 2015 at 11:00 AM, Linda Knippers <linda.knippers@hp.com> wrote: > >> Wait, point of clarification, DCRs (dimm-control-regions) have RFICs, > >> not MEMDEVs (memory-device-to-spa-mapping). Toshi's original report > >> was that an NFIT with a SPA+MEMDEV was failing to enable a PMEM > >> device. That specific problem can be fixed by either deleting the > >> MEMDEV, or adding a DCR. > > > > By a DCR, do you mean a DCR structure or SPA with Control Region GUID? > > Hmm, I meant a DCR as defined below. I agree you would not need a "SPA-DCR". > > > Adding a DCR structure does not solve this issue since it requires SPA > > with Control Region GUID, which battery-backed DIMMs do not have. > > I would not go that far, half of a DCR entry is relevant for any > NVDIMM, and half is only relevant if a DIMM offers BLK access: > > struct acpi_nfit_dcr { > u16 type; > u16 length; > u16 dcr_index; > u16 vendor_id; > u16 device_id; > u16 revision_id; > u16 sub_vendor_id; > u16 sub_device_id; > u16 sub_revision_id; > u8 reserved[6]; > u32 serial_number; > u16 fic; > <<<<< BLK relevant fields start here <<<<< > u16 num_bcw; > u64 bcw_size; > u64 cmd_offset; > u64 cmd_size; > u64 status_offset; > u64 status_size; > u16 flags; > u8 reserved2[6]; > };
Yes, we do have a DCR entry. But we do not have a SPA-DCR.
The previous issue I reported to nd_mem_init() was caused by the fact that there was no "SPA-DCR". nd_mem_init() requires SPA-DCR to initialize nd_mem objects.
> >> Of course, if you add a DCR with a different intended DSM layout than > >> the DSM-example-interface the driver will need to add support for > >> handling that case. > > > > Yes, we consider to add different _DSMs for management. We do not need > > the nd_acpi driver to support it now, but we need this framework to work > > without the DSM-example-interface present. > > > > One possible workaround is that I could ignore MEMDEV entries that do > not have a corresponding DCR. This would enable nd_namespace_io > devices to be surfaced for your use case. Would that work for you? > I.e. do you need the nfit_handle exposed?
We have MEMDEV entries and their corresponding DCR entries. ACPI 6.0 states that NVDIMM control region structure index must contain a non-zero value in a MEMDEV entry, so I think they must correspond.
Yes, we need this framework to enumerate all entries.
Thanks, -Toshi
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