Re: [PATCH 13/17] docs: add Rust documentation

On Wed, Jul 14, 2021 at 8:38 PM Nick Desaulniers
[off-list ref] wrote:

Is rust-analyzer necessary to talk about? I think most kernel
developers aren't using LSP clients, so it doesn't seem necessary to
talk about for kernel development IMO.  If a developer would like to
use an LSP client, they should refer to the documentation of their LSP
client.

I think it is fair to advertise it given we have support for
generating its configuration.

Otherwise, people might miss the script and spend time generating a
configuration by hand (which takes quite some time and would not carry
the `CONFIG_*` settings etc.).

And they may start using it if they did not hear about it! :)

Should Documentation/process/changes.rst be updated to note which
versions of all of these tools are currently supported?

For the ones required for building, they are already there (i.e.
`rustc` and `bindgen`).

For the rest, most come with the Rust toolchain, so I think there is
no need to list them explicitly. For `rust-analyzer`, it is "rolling",
so it does not make much sense to put it in any case.

For the compat table, for 32b ARM, why is v6 supported but not v7? Why
only when optimizations are enabled?

For arch support, we only have a few fixed Rust target files for the
moment as examples (thus we picked v6) -- we will generate those with
a script later on.

For particular restrictions (such as the optimization level), we will
look into solving those bits later on. In any case, it is not a
priority, since less than `-O2` is intended only for kernel hacking.

Doesn't this also depend on rustc having support for a given target
triple? Just because LLVM has a backend for a given architecture
doesn't mean rustc can target it, right?

No -- currently we use custom target files instead of particular
triples (see previous point), which are basically the settings `rustc`
forwards to LLVM for codegen.

Cheers,
Miguel