Re: [RFC PATCH v4 2/7] rust: add bindgen step as a meson dependency

[Daniel P . Berrangé]

On Tue, Jul 09, 2024 at 02:28:38PM +0200, Paolo Bonzini wrote:
> On Tue, Jul 9, 2024 at 2:09 PM Peter Maydell <peter.maydell@linaro.org> wrote:
> >  * what is the actual baseline requirement? We definitely want
> >    to support "using rustup on an older system" (should be no
> >    problem) and "current distro building QEMU using the distro's
> >    rust", I assume. It would certainly be nice to have "building
> >    QEMU on the older-but-still-in-our-support-list distro releases
> >    with that distro's rust", but this probably implies not just
> >    a minimum rust version but also a limited set of crates.
> 
> I don't think limiting ourselves to the set of crates in the distro is
> feasible. It's not the way the language works, for example I tried
> checking if the "cstr" crate exists and I didn't find it in Debian.

Yep, Rust is new enough that it is highly likely that crates will be
missing in multiple distros.

For ordinary users, cargo will happily download the missing pieces
so its not an issue.

For distro packagers, they'll just have to either package up the crates,
or bundle them in their QEMU build. Cargo makes the latter easy at
least. If distros don't want bundling, they'll need to go the more
involved route of packaging deps.

IOW, from a distro POV, IMHO, we should focus on the Rust toolchain
versions we need as the minimum bar.

With regards,
Daniel
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