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SubjectRe: [Linux-nvdimm] [PATCH 04/21] nd: create an 'nd_bus' from an 'nfit_desc'
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On Tue, 2015-04-21 at 12:58 -0700, Dan Williams wrote:
> On Tue, Apr 21, 2015 at 12:35 PM, Toshi Kani <toshi.kani@hp.com> wrote:
> > On Fri, 2015-04-17 at 21:35 -0400, Dan Williams wrote:
> > :
> >> +
> >> +static int nd_mem_init(struct nd_bus *nd_bus)
> >> +{
> >> + struct nd_spa *nd_spa;
> >> +
> >> + /*
> >> + * For each SPA-DCR address range find its corresponding
> >> + * MEMDEV(s). From each MEMDEV find the corresponding DCR.
> >> + * Then, try to find a SPA-BDW and a corresponding BDW that
> >> + * references the DCR. Throw it all into an nd_mem object.
> >> + * Note, that BDWs are optional.
> >> + */
> >> + list_for_each_entry(nd_spa, &nd_bus->spas, list) {
> >> + u16 spa_index = readw(&nd_spa->nfit_spa->spa_index);
> >> + int type = nfit_spa_type(nd_spa->nfit_spa);
> >> + struct nd_mem *nd_mem, *found;
> >> + struct nd_memdev *nd_memdev;
> >> + u16 dcr_index;
> >> +
> >> + if (type != NFIT_SPA_DCR)
> >> + continue;
> >
> > This function requires NFIT_SPA_DCR, SPA Range Structure with NVDIMM
> > Control Region GUID, for initializing an nd_mem object. However,
> > battery-backed DIMMs do not have such control region SPA. IIUC, the
> > NFIT spec does not require NFIT_SPA_DCR.
> >
> > Can you change this function to work with NFIT_SPA_PM as well?
>
> NFIT_SPA_PM ranges are handled separately from nd_mem_init(). See
> nd_region_create() in patch 10.

If nd_mem_init() does not initialize nd_mem objects, nd_bus_probe() in
core.c fails in nd_bus_init_interleave_sets() and skips all subsequent
nd_bus_xxx() calls. So, nd_region_create() won't be called.

nd_bus_init_interleave_sets() fails because init_interleave_set()
returns -ENODEV if (!nd_mem).

BTW, there are two nd_bus_probe() in bus.c and core.c, which is
confusing.

Thanks,
-Toshi




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