Re: [PATCH v2 2/2] samples: rust: fwctl: add sample code for fwctl

[Zhi Wang <zhiw@nvidia.com>]

On Thu, 22 Jan 2026 13:16:29 -0800
John Hubbard <jhubbard@nvidia.com> wrote:

> On 1/22/26 1:06 PM, Danilo Krummrich wrote:
> > On Thu Jan 22, 2026 at 9:58 PM CET, Jason Gunthorpe wrote:
> >> On Thu, Jan 22, 2026 at 10:42:31PM +0200, Zhi Wang wrote:
> >>> This patch adds a sample Rust driver demonstrating the usage of the
> >>> fwctl Rust abstractions. Add sample code for creating a FwCtl
> >>> device, getting device info and issuing an RPC.
> >>>
> >>> Cc: Danilo Krummrich <dakr@kernel.org>
> >>> Cc: Jason Gunthorpe <jgg@nvidia.com>
> >>> Signed-off-by: Zhi Wang <zhiw@nvidia.com>
> >>> ---
> >>>  samples/rust/Kconfig              |  11 +++
> >>>  samples/rust/Makefile             |   1 +
> >>>  samples/rust/rust_driver_fwctl.rs | 136
> >>> ++++++++++++++++++++++++++++++ 3 files changed, 148 insertions(+)
> >>>  create mode 100644 samples/rust/rust_driver_fwctl.rs
> >>
> >> Is this normal for Rust? Can we delete it when a real driver is
> >> merged?
> >>
> >> I'm not so keen on sample drivers, I've spent far too much time lately
> >> touching sample drivers that nobody ever uses :(
> > 
> > I think it is pretty useful for review purposes (at least as long as
> > the first real user is not yet ready) to see how it turns out from a
> > user perspective.
> > 
> > It may also be pretty useful for people starting out with Rust in the
> > kernel, as the samples have a very limited scope compared to real
> > drivers.
> > 
> > But there is no policy or anything, i.e. no need to keep it. There's
> > also no need to even land it if you prefer not to do so.
> 
> Zhi, the real code that uses this for vGPU is going to be posted
> soon-ish, right? So we could use this patch as a review assist, like
> Danilo mentions, but not merge it, because the real code will suffice to
> exercise the new fwctl functionality.
> 

I am OK with any solutions. My motivation of updating this one is because
of many changes and improvements in this re-spin comparing to the RFC. As
Jason/Danilo gave quite some feedback on RFC (Thanks for the review
efforts!), I would like to start the review before the vGPU patches.

Z.

> thanks,