Re: [PATCH 3/3] platform/wmi: Expose the raw WDG data in sysfs

["Pali Rohár" <pali.rohar@gmail.com>]

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On Friday 04 August 2017 17:03:07 Andy Lutomirski wrote:
> On Wed, Aug 2, 2017 at 12:49 AM, Pali Rohár <pali.rohar@gmail.com>
> wrote:
> > On Tuesday 01 August 2017 19:22:32 Darren Hart wrote:
> >> Pali, how does the "magic number identifier" in the BMOF map to
> >> the object_id? Have we retained that information in what we
> >> export today?
> > 
> > MOF describe C++ like object system and for particular structures
> > or methods there is GUID and WMI id.
> > 
> > When you want to call WMI function implemented in ACPI you need to
> > know: * name of ACPI function
> > * instance number
> > * WMI id
> > * structure of input buffer
> > 
> > Name of ACPI function is taken from _WDG where is mapping from GUID
> > to object_id and ACPI function consist of well-known prefix and
> > object_id as a suffix. GUID is present in MOF. Where to get
> > correct instance number is still question for me. WMI id and
> > structure of input buffer is described in MOF.
> 
> I assume that any user API for making WMI calls will have userspace
> pass in either the GUID or maybe the MOF method name, not the object
> id.

So... When calling WMI method of some class it is really needed to
supply also instance id. On Windows caller needs to specify Instance
Name, e.g. ACPI\PNP0C14\0_0 which looks like correspondent to instance
id 0. ACPI\PNP0C14\0_2 is then to instance id 2.

Toshiba has triple (class, method, instance) in their BIOS WMI
documentation [1].

Therefore userspace would need to know instance count which is stored in
_WDG for doing WMI call.

Is there already exported instance count via sysfs?

[1] - https://aps2.toshiba-tro.de/kb0/TSB3803HR0000R01_TOSHIBA_BIOS_WMI_Interface_Guide_-_13_Rev_1.1.pdf

-- 
Pali Rohár
pali.rohar@gmail.com

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