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Date: Thu, 17 Sep 2026 16:50:07 +0200
Message-Id: <DLHOBJB1NYJA.3FCP9OLPBVRZA@kernel.org>
Subject: Re: [PATCH 12/13] vfio/nvidia-vgpu: add the NVIDIA vGPU VFIO
 variant driver
Cc: "Alex Williamson" <alex@shazbot.org>, "Zhi Wang" <zhiw@nvidia.com>,
 <acourbot@nvidia.com>, <yishaih@nvidia.com>, <skolothumtho@nvidia.com>,
 <kevin.tian@intel.com>, <airlied@gmail.com>, <simona@ffwll.ch>,
 <ojeda@kernel.org>, <alex.gaynor@gmail.com>, <boqun.feng@gmail.com>,
 <gary@garyguo.net>, <bjorn3_gh@protonmail.com>, <lossin@kernel.org>,
 <a.hindborg@kernel.org>, <aliceryhl@google.com>, <tmgross@umich.edu>,
 <jhubbard@nvidia.com>, <ecourtney@nvidia.com>, <cjia@nvidia.com>,
 <smitra@nvidia.com>, <kjaju@nvidia.com>, <alkumar@nvidia.com>,
 <ankita@nvidia.com>, <aniketa@nvidia.com>, <kwankhede@nvidia.com>,
 <targupta@nvidia.com>, <nova-gpu@lists.linux.dev>,
 <linux-kernel@vger.kernel.org>, <zhiwang@kernel.org>, <kvm@vger.kernel.org>
To: "Jason Gunthorpe" <jgg@nvidia.com>
From: "Danilo Krummrich" <dakr@kernel.org>
References: <20260905081116.106613-13-zhiw@nvidia.com>
 <DLCRZLO06SIO.LS7TWQXIPZSQ@kernel.org>
 <20260914121217.70fa0d93@shazbot.org>
 <DLFD2ZDSK9YQ.3A4R66G8UJMD8@kernel.org>
 <20260915120148.7548a8ca@shazbot.org>
 <DLG7C7MLGSTC.2GSTD84WI595N@kernel.org>
 <20260916141718.GU3968357@nvidia.com>
 <DLGUPX9KPFKF.12CU304YAST79@kernel.org>
 <20260916162817.GW3968357@nvidia.com>
 <DLGXS4SCP3VT.28XXX09BL963U@kernel.org>
 <20260917132829.GA3968357@nvidia.com>
In-Reply-To: <20260917132829.GA3968357@nvidia.com>

On Thu Sep 17, 2026 at 3:28 PM CEST, Jason Gunthorpe wrote:
> On Wed, Sep 16, 2026 at 08:02:17PM +0200, Danilo Krummrich wrote:
>> >> TBH, I don't think it makes a difference; having Rust abstractions is=
 pretty
>> >> much the same as having another driver. I.e. it would be equivalent t=
o saying
>> >> "before we accept another pci-vfio driver we need to do some rework".
>> >
>> > Well, it is, but thats the point when judging effort..
>>=20
>> So it seems that we agree that there isn't really a difference between a=
dding a
>> new C or Rust driver in this regard.
>
> To be clear I was trying to say I think you are are underestimating
> how much work this is and how long it will take. Including all the
> preconditon C reworks has to be included when considering how much
> work is involved.

I'm not sure I follow what you mean by "preconditon C reworks".

Do you refer to the drvdata thing? That seems rather trivial to address?

Or do you refer to other C core reworks people are working on? If so, they =
are
only relevant if they affect the drivers. And if they affect the drivers,
there's not really a difference between adding a new C driver and adding a =
Rust
abstraction.

> Why can't we just go forward with what Zhi already drafted? Do we
> really need another side quest?

Because I don't think it is a side quest. As mentioned, the FFI layer is al=
ready
more complicated than the Rust abstraction we need, and I also don't see th=
at
this work is progressed further than the Rust abstraction I drafted. So, wh=
y not
just go for the proper solution right away?

I still have to finish some talks, but I could probably finish that work un=
til
LPC and then we can walk through it?

> I cannot forsee rust bindings for vfio until sometime in 2027.

What is different in 2027 than is now?