Re: [PATCH 0/2] virtio: Add vhost-user-gpio device's support

[Viresh Kumar]

On 17-01-22, 10:11, Alex Bennée wrote:
> 
> "Michael S. Tsirkin" <mst@redhat.com> writes:
> 
> > On Wed, Jan 12, 2022 at 05:04:57PM +0530, Viresh Kumar wrote:
> >> Hello,
> >> 
> >> This patchset adds vhost-user-gpio device's support in Qemu. The support 
> >> for the
> >> same has already been added to virtio specification and Linux Kernel.
> >> 
> >> A Rust based backend is also in progress and is tested against this 
> >> patchset:
> >> 
> >> https://github.com/rust-vmm/vhost-device/pull/76
> >
> >
> > I'm reluctant to add this with no tests in tree.
> > Want to write a minimal libhost-user based backend?

I actually have one already, that I wrote before attempting the Rust
counterpart, but never upstreamed as I am not sure if anyone is ever
going to use it, as I am not. And I thought what's the point of
merging code which I will never end up using.

I am not sure what test I can add here to make sure this doesn't
breaks in future though.

> This is going to be a problem going forward as we have more out-of-tree
> backends written as a first preference. While the first couple of vhost
> devices have C implementations in contrib before we worked on the rust
> version I think we are getting to the point of skipping a first C
> version for future devices.
> 
> However I notice we have qtest/vhost-user-test.c so would that be enough
> to ensure we can instantiate the device and a basic vhost-user
> initialisation sequence doesn't cause it to crap out. This obviously
> won't be exercising the virtq processing itself but does that really
> exercise any of QEMU's boilerplate anyway?
> 
> > We also need some maintainers to step up.
> 
> You mean more reviewers for the vhost and virtio sections of QEMU's
> maintainers?

And I too was waiting for replies on these. I can surely write
something up if you guys feel there is a need. I just want to
understand it better.

-- 
viresh