Re: [ndctl PATCH v4 2/6] libcxl: add accessors for capacity fields of the IDENTIFY command

[Alison Schofield <alison.schofield@intel.com>]

Got it, thanks!
<eom>

On Tue, Feb 08, 2022 at 12:34:23PM -0800, Dan Williams wrote:
> On Mon, Feb 7, 2022 at 3:06 PM <alison.schofield@intel.com> wrote:
> >
> > From: Alison Schofield <alison.schofield@intel.com>
> >
> > Users need access to a few additional fields reported by the IDENTIFY
> 
> Ah, I see the "Users need" pattern... To me, the "Users need"
> statement is a step removed / secondary from the real driving
> motivation which is the "CXL PMEM provisioning model specifies /
> mandates".
> 
> It feels like a watered down abstraction to me.
> 
> > mailbox command: total, volatile_only, and persistent_only capacities.
> > These values are useful when defining partition layouts.
> >
> > Add accessors to the libcxl API to retrieve these values from the
> > IDENTIFY command.
> >
> > The fields are specified in multiples of 256MB per the CXL 2.0 spec.
> > Use the capacity multiplier to convert the raw data into bytes for user
> > consumption.
> >
> > Signed-off-by: Alison Schofield <alison.schofield@intel.com>
> > ---
> >  cxl/lib/libcxl.c   | 36 ++++++++++++++++++++++++++++++++++++
> >  cxl/lib/libcxl.sym |  3 +++
> >  cxl/libcxl.h       |  3 +++
> >  3 files changed, 42 insertions(+)
> >
> > diff --git a/cxl/lib/libcxl.c b/cxl/lib/libcxl.c
> > index 33cf06b..e9d7762 100644
> > --- a/cxl/lib/libcxl.c
> > +++ b/cxl/lib/libcxl.c
> > @@ -2322,6 +2322,42 @@ CXL_EXPORT unsigned int cxl_cmd_identify_get_label_size(struct cxl_cmd *cmd)
> >         return le32_to_cpu(id->lsa_size);
> >  }
> >
> > +static struct cxl_cmd_identify *
> > +cmd_to_identify(struct cxl_cmd *cmd)
> > +{
> > +       if (cxl_cmd_validate_status(cmd, CXL_MEM_COMMAND_ID_IDENTIFY))
> > +               return NULL;
> > +
> > +       return cmd->output_payload;
> > +}
> > +
> > +CXL_EXPORT unsigned long long
> > +cxl_cmd_identify_get_total_size(struct cxl_cmd *cmd)
> > +{
> > +       struct cxl_cmd_identify *c;
> > +
> > +       c = cmd_to_identify(cmd);
> > +       return c ? capacity_to_bytes(c->total_capacity) : ULLONG_MAX;
> > +}
> > +
> > +CXL_EXPORT unsigned long long
> > +cxl_cmd_identify_get_volatile_only_size(struct cxl_cmd *cmd)
> > +{
> > +       struct cxl_cmd_identify *c;
> > +
> > +       c = cmd_to_identify(cmd);
> > +       return c ? capacity_to_bytes(c->volatile_capacity) : ULLONG_MAX;
> > +}
> > +
> > +CXL_EXPORT unsigned long long
> > +cxl_cmd_identify_get_persistent_only_size(struct cxl_cmd *cmd)
> > +{
> > +       struct cxl_cmd_identify *c;
> > +
> > +       c = cmd_to_identify(cmd);
> > +       return c ? capacity_to_bytes(c->persistent_capacity) : ULLONG_MAX;
> 
> Same style comments as last patch, but otherwise:
> 
> Reviewed-by: Dan Williams <dan.j.williams@intel.com>