Re: [PATCH] libnvdimm: clean up command definitions

[Yasunori Goto <y-goto@jp.fujitsu.com>]

> On Tue, Aug 29, 2017 at 3:09 AM, Yasunori Goto <y-goto@jp.fujitsu.com> wrote:
> >> On Mon, Aug 28, 2017 at 6:03 PM, Yasunori Goto <y-goto@jp.fujitsu.com> wrote:
> >> >> On Mon, Aug 28, 2017 at 1:50 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote:
> >> >> >
> >> >> > On Mon, Aug 28, 2017 at 08:45:32AM -0700, Dan Williams wrote:
> >> >> >> Remove the command payloads that do not have an associated libnvdimm
> >> >> >> ioctl. I.e. remove the payloads that would only ever be carried in the
> >> >> >> ND_CMD_CALL envelope. This prevents userspace from growing unnecessary
> >> >> >> dependencies on this kernel header when userspace already has everything
> >> >> >> it needs to craft and send these commands.
> >> >> >
> >> >> > Userspace needs to include linux/ndctl.h to make the call as
> >> >> > that is where nd_cmd_pkg is defined.
> >> >> >
> >> >> > So you want to have some structures defined in ndctl.h and other
> >> >> > defined in the to be created libndctl-nfit.h?  Plus a third header
> >> >> > file for the HPE non-root calls?
> >> >>
> >> >> Yes. ndctl.h exports the ioctl command payloads, everything that goes
> >> >> inside of ND_CMD_CALL is defined by userspace headers. The
> >> >> libndctl-nfit.h header is proposed as a place to land vendor agnostic
> >> >> NFIT-defined payloads, and any vendor specific definitions would
> >> >> remain internal to libndctl as they are today.
> >> >>
> >> >> > Will libndctl-nfit.h be generally available and installed?
> >> >>
> >> >> Yes, that's the plan.
> >> >>
> >> >> > Will it be clean so that other applications can use it to get these
> >> >> > definitions?  Or will it be loaded w/ a bunch of stuff only useful
> >> >> > to your ndctl command?
> >> >>
> >> >> Yes, that's the plan. It's a bug if libndctl-nfit.h is not generically
> >> >> clean for issuing the NFIT root device commands via some ND_CMD_CALL
> >> >> helpers from the base libndctl library.
> >> >>
> >> >> In other words libndctl-nfit.h defines the payload and libndctl
> >> >> defines some general helpers for issuing commands.
> >> >
> >> > Maybe I don't understand your idea yet, let me confirm it.
> >> >
> >> > Certainly, current acpi driver does not need these definitions.
> >> > But, I think nfit_test.ko will need them to emulate these features.
> >> >
> >> > Do you intend that libndctl-nfit.h should be defined at "include/uapi/linux/"
> >> > directory?
> >> > Otherwise, it should be defined at "tools/testing/nvdimm/" or
> >> > "tools/testing/nvdimm/test" ?
> >>
> >> nfit_test will need its own internal / private copy of these payloads
> >> in tools/testing/nvdimm/test so it can emulate how the bios behaves.
> >> The include/uapi/linux directory is for user to kernel interface
> >> definitions and these command payloads are purely an interface to bios
> >> / firmware.
> >>
> >
> > Hmm,
> >
> > I'm trying to make libndctl-nfit.h under tools/testing/nvdimm/nfit/,
> > and trying to move NFIT_CMD_TRANSLATE_SPA from drivers/acpi/nfit/core.c to it.
> >
> > But I noticed that drivers/acpi/nfit/core.c still uses the definition
> > in acpi_nfit_init_dsms().
> >
> > ----
> > static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc)
> > {
> >         struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc;
> >         const guid_t *guid = to_nfit_uuid(NFIT_DEV_BUS);
> >
> >         :
> >
> >         dsm_mask =
> >                 (1 << ND_CMD_ARS_CAP) |
> >                 (1 << ND_CMD_ARS_START) |
> >                 (1 << ND_CMD_ARS_STATUS) |
> >                 (1 << ND_CMD_CLEAR_ERROR) |
> >                 (1 << NFIT_CMD_TRANSLATE_SPA) |
> >                 (1 << NFIT_CMD_ARS_INJECT_SET) |
> >                 (1 << NFIT_CMD_ARS_INJECT_CLEAR) |
> >                 (1 << NFIT_CMD_ARS_INJECT_GET);
> >         for_each_set_bit(i, &dsm_mask, BITS_PER_LONG)
> >                 if (acpi_check_dsm(adev->handle, guid, 1, 1ULL << i))
> >                         set_bit(i, &nd_desc->bus_dsm_mask);
> > ---
> >
> > Though it seems to be necessary yet,
> > do you have any idea to remove it?
> 
> Here's the end state I'm looking for...
> 
> 1/ drivers/acpi/nfit/core.c keeps its current definitions of the
> NFIT_CMD_ numbers since it needs to validate the DSM command number
> mask
> 
> 2/ tools/testing/nvdimm/test/nfit.h grows private definitions of only
> the command payloads that it emulates
> 
> 3/ ndctl in userspace grows a new ndctl/libndctl-nfit.h with all the
> payloads defined in ACPI. Ideally we can deprecate all the payload
> definitions in ndctl.h and only use the ND_CMD_CALL ioctl plus the
> ndctl/libndctl-nfit.h definitions. Although, since label reading has
> moved away from DSMs we'll always need the separate
> ND_CMD_{GET,SET}_CONFIG_DATA ioctls. The libndctl-nfit.h header should
> be listed in pkginclude_HEADERS.

Hmm, Ok. I'll try.

Thanks for your explanation.