Re: [PATCH 2/2] samples: rust: add a USB driver sample

["Danilo Krummrich" <dakr@kernel.org>]

On Sat Sep 6, 2025 at 2:41 PM CEST, Daniel Almeida wrote:
>>> 
>>> I thought that an iterative approach would work here, i.e.: merge this, then
>>> URBs, then more stuff, etc.
>> 
>> Ah, that makes sense, I didn't realize you want that here.  What USB
>> device do you want to write a rust driver for?  Are you going to need
>> bindings to the usb major number, or is it going to talk to some other
>> subsystem instead?
>> 
>> Right now, these bindings don't really do anything USB specific at all
>> except allow a driver to bind to a device.
>> 
>> thanks,
>> 
>> greg k-h
>
> To be honest, I'm trying to pave the way for others.
>
> I often hear people saying that they would look into Rust drivers if only they
> did not have to write all the surrounding infrastructure themselves. On the
> other hand, there is no infrastructure because there are no drivers.

I think saying that there is no infrastructure for writing Rust drivers is not
accurate:

We already have lots of infrastructure in place, such as device / driver core
infrastructure, PCI, platform (with OF and ACPI), faux and auxilirary bus
infrastructure, I/O, workqueues, timekeeping, cpufreq, firmware, DMA and a lot
more.

Not to forget the absolute core primitives, such as kernel allocators, xarray,
locking infrastructure or very recently maple tree and LKMM atomics.

Besides that we also have a lot of infrastructure that we do not have in C
because it's simply not possible or applicable.

However, it is in fact true that there is no USB infrastructure yet.

> It's a chicken and egg problem that I am trying to solve.

This is exactly why we develop Nova in-tree, such that we have a justification
for adding all this infrastructure.

Lot's of the stuff I listed above originates from that and I think the Nova
project has proven that we can break this chicken and egg problem. I think
one proof for that is that Tyr follows the approach.

However, I agree that it still remains that someone (i.e. some driver) has to
take the burden of doing the "heavy lifting" for a particular subsystem.