Re: The Case for Rust (in the base system)

From: Warner Losh <imp_at_bsdimp.com>
Date: Sat, 20 Jan 2024 22:31:23 UTC
On Sat, Jan 20, 2024 at 11:45 AM Aleksandr Fedorov <wigneddoom@yandex.ru>
wrote:

> What about external dependencies?
>
> https://github.com/Axcient/freebsd-nfs-exporter/blob/master/Cargo.toml#L19
> https://github.com/asomers/gstat-rs/blob/master/gstat/src/main.rs#L20
>
> Is there any plan for which crates we should take into the base system?
>
> We have had C++ in base for many years, but I don’t see any good libraries
> for CLI, logging, JSON, etc.
>
>
> https://doc.rust-lang.org/rustc/platform-support.html#tier-1-with-host-tools
>
> Where is the support for Freebsd as a primary platform? ARM, RISC-V,
> Power? Should we rewrite devd?
>
> I think we need to start by providing official repositories (e.g
> git.FreeBSD.org/rust.git or git.FreeBSD.org/go.git)
> for different languages that include stable bindings to the system API:
> - sysctl
> - libgeom
> - libifconfig
> - netgraph
> - jail
> - etc.
>
> So that it’s not just some anonymous on crates.io that represents these
> bindings, but our community.
> Officially, with support for a stable ABI for releases, security patches,
> etc.
>
> After this, it will be possible to think about which components to include
> in the base system.
>
> I would be glad to see a more modern language than C in the database, but
> I’m afraid that it will be like with C++,
> that we will get a couple of daemons and utilities and that’s all.
>

These are all good questions that need good answers, though necessarily to
get started.

But the other question that occured to me after my last posting was "What
about build integration?"
How much of the rust automation do we take in vs how much do we drive from
a future bsd.rust.mk.
I can sketch out bsd.rust.mk (to pick an arbitrary name, we'd likely need
one for what we traditionally
think of as libraries (which may or may not map 1:1 onto crates: we could
have c callable libraries
written in rust in the future, for example) and one for binaries.
Initially, though, if we go with the
'make rust tests possible' then we'd likely need the appropriate packages
installed for whatever
dependencies we'd have in the tests. This would give us a taste for what
we'd need to do for
base, I'd think. Once we had that notion, I can easily see there needing to
be some sort of
rust bindings for ATF/kyua as one of the first libraries / crates that
would test that aspect of
the build system. That all would be up to the people writing the tests in
rust, I'd imagine.

While I could jot out the basics of this integration (so one could just add
the rust
tools to a subdir or subdirs, include the bsd.rust.mk or whatever and then
it would build
if rust is enabled, and would emit a warning it was skipped because rust
was disabled).
We'd find out if this is workable or not and iterate from there. But that
would also require
active participation from the rust advocates to make it a reality: I can
put together the
build infrastructure for the disabled case, but likely can't on my own do
the rust enabled
case. I'd be happy to work with someone to do that, but I'm not going to be
able to do
that myself: my need for rust is slight, my knowledge of rust is weak, etc.
Working with
someone (or ideally several someones), though it could become reality. So
please contact
me if you'd like to work on this.

Warner


> 20.01.2024, 19:51, "Alan Somers" <asomers@freebsd.org>:
>
> In a recent thread on src-committers, we discussed the costs and
> benefits of including Rust code in the FreeBSD base system. To
> summarize, the cost is that it would double our build times. imp
> suggested adding an additional step after buildworld for stuff that
> requires an external toolchain. That would ease the build time pain.
> The benefit is that some tools would become easier to write, or even
> become possible. Here is a list of actual and potential Rust projects
> that could benefit from being in-tree. If anybody else has items to
> add, I suggest moving this into the project wiki:
>
> Stuff that could only be written in Rust if it were in base
> ===========================================================
>
> * ctl-exporter (I started this, but discovered that the CTL stats API is
>   unstable, so it can't live in ports. Instead, I had to do it in C).
>
> https://github.com/freebsd/freebsd-src/commit/1a7f22d9c211f504f6c48a86401469181a67ec34
>
> * fusefs tests. Absolutely impossible to do in C. I considered Rust, but
> went
>   with C++ so they could live in base. They are too closely coupled to
>   fusefs(5) to live out-of-tree.
>   https://github.com/freebsd/freebsd-src/tree/main/tests/sys/fs/fusefs
>
> * devd. Currently C++, but imp suggested a rewrite.
>   https://github.com/freebsd/freebsd-src/tree/main/sbin/devd
>
> * zfsd. Currently C++, but I've long pondered a rewrite. Using Rust would
>   make it more testable.
>   https://github.com/freebsd/freebsd-src/tree/main/cddl/usr.sbin/zfsd
>
> * nscd. Currently C, but confusing and with no test coverage. I've
>   contemplated a rewrite myself, but I don't want to do it in C.
>   https://github.com/freebsd/freebsd-src/tree/main/usr.sbin/nscd
>
> * The userland portion of the 802.11ac and Lightning stacks. scottl
> suggested
>   that these were good candidates for Rust.
>
> * freebsd-kpi-r14-0 . https://crates.io/crates/freebsd-kpi-r14-0
>
> Stuff that can live in ports, but would be nicer in base
> ========================================================
>
> * gstat-rs https://crates.io/crates/gstat
>
> * geom-exporter (I've started this, but haven't published it)
>
> * nfs-exporter https://crates.io/crates/freebsd-nfs-exporter
>
> * virtiofsd-rs . Nobody has yet tried to port it to FreeBSD. But if the
>   connection to bhyve(8) is too intimate, it might be hard to do in ports.
>   https://gitlab.com/virtio-fs/virtiofsd
>
> * jail-exporter https://crates.io/crates/jail_exporter
>
> * Various jail managers have been attempted in Rust. I think these are
> fine in
>   ports, but others like Goran Mekic have opined that they should be moved
> to
>   base instead.
>
> * musikid's pjdfstest rewrite. I think it would be great to start using
> this
>   to test the base system's file systems. If the tests themselves lived in
>   base, they would be easier to sync with file system development.
>   https://github.com/musikid/pjdfstest
>
> * pf-rs. I suspect that the API isn't very stable.
>   https://crates.io/crates/pf-rs
>
> * benchpmc. The pmc counter names changes between releases.
>   https://crates.io/crates/benchpmc
>
> FreeBSD-related applications that are just fine in ports
> =========================================================
>
> * fsx-rs. Unlike pjdfstest, this only tests datapath APIs. Those are
> usually
>   more stable than control path APIs, so I think there's little to be
> gained by
>   moving this into base. https://crates.io/crates/fsx
>
> * ztop. It uses ZFS's kstats sysctl interface, which is pretty stable.
>   https://crates.io/crates/ztop
>
> * iocage-provision https://crates.io/crates/iocage-provision
>
> * rsblk https://crates.io/crates/rsblk
>
> * xfuse https://github.com/KhaledEmaraDev/xfuse
>
> Other FreeBSD-related libraries in Rust
> =======================================
> Just see the list at https://crates.io/keywords/freebsd
>
>