Re: [RFC PATCH v2 3/5] rust: add PL011 device model

[Zhao Liu <zhao1.liu@intel.com>]

Hi Paolo,

On Thu, Jun 13, 2024 at 09:56:39AM +0200, Paolo Bonzini wrote:
> Date: Thu, 13 Jun 2024 09:56:39 +0200
> From: Paolo Bonzini <pbonzini@redhat.com>
> Subject: Re: [RFC PATCH v2 3/5] rust: add PL011 device model
> 
> Il gio 13 giu 2024, 09:13 Daniel P. Berrangé <berrange@redhat.com> ha
> scritto:
> 
> > On Wed, Jun 12, 2024 at 11:27:04PM +0200, Paolo Bonzini wrote:
> > > Il mer 12 giu 2024, 22:58 Manos Pitsidianakis <
> > > manos.pitsidianakis@linaro.org> ha scritto:
> > >
> > > > In any case, it is out of scope for this RFC. Introducing wrappers
> > would
> > > > be a gradual process.
> > > >
> > >
> > > Sure, how would you feel about such bindings being developed on list, and
> > > maintained in a (somewhat) long-lived experimental branch?
> >
> > IMHO any higher level binding APIs for Rust should be acceptable in the
> > main QEMU tree as soon as we accept Rust functionality. They can evolve
> > in-tree based on the needs of whomever is creating and/or consuming them.
> >
> 
> My question is the opposite, should we accept Rust functionality without
> proper high level bindings? I am afraid that, if more Rust devices are
> contributed, it becomes technical debt to have a mix of idiomatic and C-ish
> code. If the answer is no, then this PL011 device has to be developed out
> of tree.

I think deeper and higher level bindings will have more opens and will
likely require more discussion and exploration. So could we explore this
direction on another reference Rust device?

I also think there won’t be too many Rust devices in the short term.
Going back to tweak or enhance existing Rust devices may not require too
much effort, once we have a definitive answer.

I wonder if x86 could also implement a rust device (like the x86 timer
you mentioned before, hw/i386/kvm/i8254.c or hw/timer/i8254.c IIRC) to
try this? Or would you recommend another x86 device? :-)

I'd be willing to help Manos try it if you think it's fine.

Regards,
Zhao