Re: [PATCH v8 02/10] nvdimm: Add wrapper for IOCTL pass thru

On Mon, Apr 11, 2016 at 4:16 PM, Jerry Hoemann <jerry.hoemann(a)hpe.com&gt; wrote: > On Mon, Apr 11, 2016 at 11:21:45AM -0700, Dan Williams wrote: >> On Mon, Mar 21, 2016 at 12:37 PM, Jerry Hoemann <jerry.hoemann(a)hpe.com&gt; wrote: >> > + >> > +/* >> > + * the list nd_family of commands. The mapping to firmware handles >> > + * is definied in the nfit_cmd_family_tbl >> > + * >> > + */ >> > +#define ND_TYPE_BUS 1 >> > +#define ND_TYPE_DIMM_INTEL1 2 >> > +#define ND_TYPE_DIMM_N_HPE1 3 >> > +#define ND_TYPE_DIMM_N_HPE2 4 >> > + >> > + >> > +#define ND_IOCTL_CALL _IOWR(ND_IOCTL, ND_CMD_CALL,\ >> > + struct nd_cmd_pkg) >> > + >> > + >> > + >> > #endif /* __NDCTL_H__ */ >> >> Looks, good, but for now lets assume there will never be such a thing >> as ND_TYPE_BUS commands or an ND_CMD_CALL for the bus. I.e. all the >> commands that currently exist for the bus are commands that the kernel >> wants to handle. In this way, struct nd_cmd_pkg is a solution to the >> problem of commands that the kernel knows exist, but has no use case >> to generate or parse itself. Commands that fit that description >> currently only exist in leaf node implementations. > > > Would user space application ever want to call commands for the bus? > > I assume the answer is yes, as there are ioctls for ND_CMD_ARS_CAP, etc., > > My thoughts here was to make the pass thru uniform, capable of calling > all the dsm functions that a user space agent might want to call. I.e > don't make user call some _DSM functions one way, and other DSM function > another way.... > Indeed that would have been nice had that been the implementation from the beginning, but binaries using the current more verbose interface are already shipping in distributions. So, the train has already left

the station on having a "one ioctl interface to rule them all" interface. Unless the ACPI working group adds a slew of kernel irrelevant commands to the bus, I don't see nd_cmd_pkg being needed at that root device level.