Re: Linux kernel in-tree Rust support

[Linus Torvalds]

On Fri, Jul 10, 2020 at 3:59 PM Josh Triplett <josh@xxxxxxxxxxxxxxxx> wrote:
>
> As I recall, Greg's biggest condition for initial introduction of this
> was to do the same kind of "turn this Kconfig option on and turn an
> option under it off" trick that LTO uses, so that neither "make
> allnoconfig" nor "make allyesconfig" would require Rust until we've had
> plenty of time to experiment with it.

No, please make it a "is rust available" automatic config option. The
exact same way we already do the compiler versions and check for
various availability of compiler flags at config time.

See init/Kconfig for things like

  config LD_IS_LLD
          def_bool $(success,$(LD) -v | head -n 1 | grep -q LLD)

and the rust support should be similar. Something like

  config RUST_IS_AVAILABLE
          def_bool $(success,$(RUST) ..sometest..)

because I _don't_ want us to be in the situation where any new rust
support isn't even build-tested by default.

Quite the reverse. I'd want the first rust driver (or whatever) to be
introduced in such a simple format that failures will be obvious and
simple.

The _worst_ situation to be in is that s (small) group of people start
testing their very special situation, and do bad and crazy things
because "nobody else cares, it's hidden".

No, thank you.

             Linus