Re: [PATCH 1/4] nvdimm: Add wrapper for IOCTL pass thru.

[Dan Williams]

On Tue, Nov 10, 2015 at 11:49 AM, Jerry Hoemann <jerry.hoemann@xxxxxxx> wrote:
> On Tue, Nov 10, 2015 at 12:51:59PM -0500, Jeff Moyer wrote:
>> Jerry Hoemann <jerry.hoemann@xxxxxxx> writes:
>>
>> > Add IOCTL type 'P' to denote NVDIMM_TYPE_PASSTHRU.
>>
>> Can't you just make passthrough a separate command?  If you actually add
>
> There are multiple conflicting NVDIMM _DSM running around, they
> are "device specific".  So, we should plan in general and not just
> for the example DSM that Intel added support for.  These DSM have
> over lapping and incompatible function ids.
>
> The Intel example is an example,  not standard. They are free to
> change it at will. So, we can't be certain there won't be a
> conflict some time in the future if we try to use their number space.
>
> I'm trying to create a generic pass thru that any vendors can use.  Putting
> this in the Intel function number space doesn't make a lot of sense to me.

It isn't the "Intel" function number space.  The fact that they
currently align is just a happy accident.  The kernel is free to break
the 1:1 ioctl number to DSM function number relationship, and I think
it would make the implementation cleaner in this case.
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