Re: [RFC v3 10/32] build-sys: add --with-rust{-target} & basic build infrastructure

[Peter Maydell <peter.maydell@linaro.org>]

On Tue, 7 Sept 2021 at 13:41, <marcandre.lureau@redhat.com> wrote:
>
> From: Marc-André Lureau <marcandre.lureau@redhat.com>
>
> Add the build-sys infrastructure to optionally build Rust code.
> Introduce a top-level workspace, so various sub-projects (libraries,
> executables etc) can be developed together, sharing the dependencies and
> output directory.
>
> If not Tier 1 (aarch64 and x86), all of the host architecture QEMU
> supports should be Tier 2:
> https://doc.rust-lang.org/nightly/rustc/platform-support.html

I don't think this is quite true -- for instance the riscv
TCG backend supports 32-bit, but the riscv 32 bit linux rust
port is down in Tier 3. But the major stuff seems to be in Tier
1 or 2.


> +if with_rust
> +  rust_target_triple = get_option('with_rust_target')
> +  if meson.is_cross_build()
> +    # more default target mappings may be added over time
> +    if rust_target_triple == '' and targetos == 'windows'
> +      rust_target_triple = host_machine.cpu() + '-pc-windows-gnu'
> +    endif
> +    if rust_target_triple == ''
> +      error('cross-compiling, but no Rust target-triple defined.')
> +    endif
> +  endif
> +endif

Not a huge fan of this... I think we would be better to always
require the user to specify the rust target triple explicitly.


> diff --git a/.gitignore b/.gitignore
> index eb2553026c..78715bc7c4 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -1,5 +1,6 @@
>  /GNUmakefile
>  /build/
> +/target/

What's this for ?

>  *.pyc
>  .sdk
>  .stgit-*

thanks
-- PMM