Re: [PATCH v1] rust: bug: skip arch-specific asm in `testlib` builds

On Sat, Aug 8, 2026 at 4:26 AM FUJITA Tomonori <[email protected]> wrote:
>
> From: FUJITA Tomonori <[email protected]>
>
> Running `make rusttest` with `ARCH=` set to an architecture other than
> the host's fails, e.g. `ARCH=arm64` on an x86_64 host:
>
> error: invalid instruction mnemonic 'brk'
>   --> rust/kernel/bug.rs:63:17
>    |
> 63 | /                 concat!(
> 64 | |                     "/* {size} */",
> 65 | |                     include!(concat!(env!("OBJTREE"), "/rust/kernel/generated_arch_warn_asm.rs")),
> 66 | |                     include!(concat!(env!("OBJTREE"), "/rust/kernel/generated_arch_reachable_asm.rs")));
>    | |_______________________________________________________________________________________________________^
>    |
> note: instantiated into assembly here
>   --> <inline asm>:1:115
>    |
>  1 |     /* 8 */.pushsection __bug_table,"aw"; .align 2; 14470: .long 14471f - .;.short 2305;.align 2; .popsection; 14471:brk 0x800
>    |                                                                                                                      ^^^
>
> The reason is that `rusttest` builds the `kernel` crate as a host
> library: it passes the `CONFIG_*` cfgs of the configured architecture,
> but not `--target`, so code generation happens for the
> host. `warn_flags!` then selects the arch-specific inline asm arm
> based on `CONFIG_*`, and the host assembler rejects it.
>
> This does not happen with the current `master` because `warn_on!` has
> no user inside the `kernel` crate itself yet, but it will as soon as
> one is added.
>
> Reported-by: Miguel Ojeda <[email protected]>
> Closes: https://lore.kernel.org/all/CANiq72n4=fz=JNKY0Jdm8BnLa=RmHB2B7s0bO47YTJ7hygqBZg@mail.gmail.com/
> Signed-off-by: FUJITA Tomonori <[email protected]>

Applied to `rust-next` -- thanks!

    Cc: [email protected]
    Fixes: dff64b072708 ("rust: Add warn_on macro")

Cheers,
Miguel