Re: [PATCH v2] nvme: allow 64-bit results in passthru commands

[Keith Busch]

On Mon, Aug 19, 2019 at 12:06:23AM -0700, Marta Rybczynska wrote:
> ----- On 16 Aug, 2019, at 15:16, Christoph Hellwig hch@xxxxxx wrote:
> > Sorry for not replying to the earlier version, and thanks for doing
> > this work.
> > 
> > I wonder if instead of using our own structure we'd just use
> > a full nvme SQE for the input and CQE for that output.  Even if we
> > reserve a few fields that means we are ready for any newly used
> > field (at least until the SQE/CQE sizes are expanded..).
> 
> We could do that, nvme_command and nvme_completion are already UAPI.
> On the other hand that would mean not filling out certain fields like
> command_id. Can do an approach like this.

Well, we need to pass user space addresses and lengths, which isn't
captured in struct nvme_command.