Re: [RFC PATCH 0/3] rust abstractions for interacting with sysfs

[Greg KH <gregkh@linuxfoundation.org>]

On Sun, Dec 08, 2024 at 02:15:42PM +0100, Daniel Sedlak wrote:
> Hello,
> For now, there are no facilities for the Rust side to tune modules written
> in Rust in runtime or for just simple debug output/statistics from
> the module. For exactly this purpose, the C has the sysfs. In this
> patch series, I implemented a minimal sysfs wrapper utilizing kobject API.
> 
> I would like to collect your thoughts on whether:
>   - Do we want something like this in the rust part of the kernel?

No.  Module parameters are from the 1990's, please let's not perpetuate
that madness into the next century if possible.

>   - Do we want to support all sysfs capabilities?

For many things, yes.  But let's add that when needed.  I'd like to see
a real user before accepting these types of things, don't just add
bindings when you don't have them as it's impossible to determine if
they are correct or not (see the recent miscdev sample driver for proof
of that, turns out that the bindings we took weren't really right, which
is fine, but it's sometimes easier to figure that out when you have a
user.)

> I implemented a sample to present the API I have chosen for the Rust part.
> It is a straightforward example that does not represent all capabilities
> of the sysfs. The documentation will be potentially improved, but I would
> like to first settle the abstractions.

What exactly do you want to represent in sysfs here?  Start with that
and we can work backwards to say what types of bindings are needed.

Almost NO kernel code should ever call "raw" kobject or sysfs calls,
with some exceptions.  Is your use case one of those exceptions?

thanks,

greg k-h