Re: Rust in Qemu BoF followup: Rust vs. qemu platform support - Marc-André Lureau

From: "Marc-André Lureau" <marcandre.lureau@gmail.com>
To: Cornelia Huck <cohuck@redhat.com>
Cc: "Peter Maydell" <peter.maydell@linaro.org>,
	"Sergio Lopez" <slp@redhat.com>,
	"Philippe Mathieu-Daudé" <f4bug@amsat.org>,
	QEMU <qemu-devel@nongnu.org>,
	hreitz@redhat.com, "Stefan Hajnoczi" <stefanha@redhat.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Stefano Garzarella" <sgarzare@redhat.com>,
	"Alex Bennée" <alex.bennee@linaro.org>,
	"David Gibson" <david@gibson.dropbear.id.au>
Subject: Re: Rust in Qemu BoF followup: Rust vs. qemu platform support
Date: Fri, 17 Sep 2021 13:54:22 +0400	[thread overview]
Message-ID: <CAJ+F1CJJvqVQrG5iPXV2s7oLbduHfAhHs0pHdZ8XbxLkNi42VQ@mail.gmail.com> (raw)
In-Reply-To: <87k0jfh88i.fsf@redhat.com>

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Hi

On Fri, Sep 17, 2021 at 1:19 PM Cornelia Huck <cohuck@redhat.com> wrote:

> On Fri, Sep 17 2021, David Gibson <david@gibson.dropbear.id.au> wrote:
>
> > Hi all,
> >
> > At the qemu-in-rust BoF at KVM Forum, I volunteered to look into
> > whether Rust supported all the host/build platforms that qemu does,
> > which is obviously vital if we want to make Rust a non-optional
> > component of the build.
> >
> > I've added the information to our wiki at:
> >       https://wiki.qemu.org/RustInQemu
>
> Thank you for doing that!
>
>
Yes, the condensed coloured matrix is much more readable than the Rust long
list. I wonder if they would also adopt it :)

> >
> > TBH, the coverage is not as good as I expected.  Linux, macOS and
> > Windows are pretty much ok, with the exception of Linux on Sparc.
> > There are a lot of gaps in *BSD support, however.
>
> Yes :(
>

Can we say reasonably that QEMU is supported on *BSD other than x86 (and
aarch64?), I wonder. Maybe we should consider moving those under the
unsupported rank.

>
> Do we actually have an idea what we would require? I'm surprised that
> there are so many targets without host tools or without std support (but
> maybe they are only missing small things.)
>

For sparc 32, it was added to support Gentoo at that time which didn't
switch to 64-bit yet (https://github.com/rust-lang/rust/pull/48297)

For the past 2-3y, Gentoo sparc is now 64 bit. (like Debian apparently for
a while)

But apparently, by lack of CI it was downgraded to Tier-3.

Is it reasonable to officially drop support for sparc 32 in QEMU too?

> >
> > I've included some notes on where the information comes from, and some
> > uncertainties in there.
> >
> > I've made an effort to get the information correct, but double
> > checking would be appreciated.
>
> I did not spot any errors on a quick cross check, but I'm not really
> sure about what the BSDs support.
>
> >
> > I haven't yet looked into the packaging situation for the Rust
> > toolchain on various platforms and distros, but I still intend to do
> > so.
>
>
>
I would share our wiki page on r/rust if you don't mind, as there are
various people that can help us fill the gaps I think.

Thanks

-- 
Marc-André Lureau

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