Re: [PATCH V7 4/4] powerpc: Enable Rust for ppc64le

["Gary Guo" <gary@garyguo.net>]

On Sun Mar 29, 2026 at 5:02 PM BST, Mukesh Kumar Chaurasiya (IBM) wrote:
> Enabling rust support for ppc64le only.

This line looks inaccurate now given previous commit just enabled it for PPC32
too.

>
> Tested on powernv9:
>
> $ uname -rm
> 6.19.0-rc8+ ppc64le
>
> $ sudo modprobe rust_minimal
> [  632.890850] rust_minimal: Rust minimal sample (init)
> [  632.890881] rust_minimal: Am I built-in? false
> [  632.890898] rust_minimal: test_parameter: 1
>
> $ sudo rmmod rust_minimal
> [  648.272832] rust_minimal: My numbers are [72, 108, 200]
> [  648.272873] rust_minimal: Rust minimal sample (exit)
>
> $ sudo modprobe rust_print
> [  843.410391] rust_print: Rust printing macros sample (init)
> [  843.410424] rust_print: Emergency message (level 0) without args
> [  843.410451] rust_print: Alert message (level 1) without args
> [  843.410477] rust_print: Critical message (level 2) without args
> [  843.410503] rust_print: Error message (level 3) without args
> [  843.410530] rust_print: Warning message (level 4) without args
> [  843.410557] rust_print: Notice message (level 5) without args
> [  843.410594] rust_print: Info message (level 6) without args
> [  843.410617] rust_print: A line that is continued without args
> [  843.410646] rust_print: Emergency message (level 0) with args
> [  843.410675] rust_print: Alert message (level 1) with args
> [  843.410691] rust_print: Critical message (level 2) with args
> [  843.410727] rust_print: Error message (level 3) with args
> [  843.410761] rust_print: Warning message (level 4) with args
> [  843.410796] rust_print: Notice message (level 5) with args
> [  843.410821] rust_print: Info message (level 6) with args
> [  843.410854] rust_print: A line that is continued with args
> [  843.410892] rust_print: 1
> [  843.410895] rust_print: "hello, world"
> [  843.410924] rust_print: [samples/rust/rust_print_main.rs:35:5] c = "hello, world"
> [  843.410977] rust_print: Arc<dyn Display> says 42
> [  843.410979] rust_print: Arc<dyn Display> says hello, world
>
> $ sudo rmmod rust_print
> [  843.411003] rust_print: "hello, world"
> [  888.499935] rust_print: Rust printing macros sample (exit)
>
> Reviewed-by: Link Mauve <linkmauve@linkmauve.fr>
> Tested-by: Link Mauve <linkmauve@linkmauve.fr>
> Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
> Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
> Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
> ---
>  arch/powerpc/Kconfig  | 1 +
>  arch/powerpc/Makefile | 7 ++++++-
>  rust/Makefile         | 6 ++++++
>  3 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 1246b3add8ff..a5f50434daf3 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -285,6 +285,7 @@ config PPC
>  	select HAVE_RELIABLE_STACKTRACE
>  	select HAVE_RSEQ
>  	select HAVE_RUST			if PPC32
> +	select HAVE_RUST			if PPC64 && CPU_LITTLE_ENDIAN
>  	select HAVE_SAMPLE_FTRACE_DIRECT	if HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
>  	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI	if HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
>  	select HAVE_SETUP_PER_CPU_AREA		if PPC64
> diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
> index 589613eaa5dc..9385db478c59 100644
> --- a/arch/powerpc/Makefile
> +++ b/arch/powerpc/Makefile
> @@ -61,7 +61,12 @@ else
>  KBUILD_LDFLAGS_MODULE += $(objtree)/arch/powerpc/lib/crtsavres.o
>  endif
>  
> -KBUILD_RUSTFLAGS 	+= --target=powerpc-unknown-linux-gnu
> +ifdef CONFIG_PPC64
> +KBUILD_RUSTFLAGS	+= --target=powerpc64le-unknown-linux-gnu

It looks like all it takes to enable PPC BE is to have

#ifdef CONFIG_CPU_LITTLE_ENDIAN
KBUILD_RUSTFLAGS	+= --target=powerpc64le-unknown-linux-gnu
#else
KBUILD_RUSTFLAGS	+= --target=powerpc64-unknown-linux-gnu
#endif

(and similarly add bindgen target)?

I think it might worth having PPC32/PPC64/PPC64LE all enabled in a single
commit, and then you can just claim Rust is enabled for PPC and have an
unconditional

    select HAVE_RUST

Thoughts?

Best,
Gary

> +KBUILD_RUSTFLAGS	+= -Ctarget-feature=-mma,-vsx,-hard-float,-altivec
> +else
> +KBUILD_RUSTFLAGS	+= --target=powerpc-unknown-linux-gnu
> +endif
>  
>  ifdef CONFIG_CPU_LITTLE_ENDIAN
>  KBUILD_CPPFLAGS	+= -mlittle-endian
> diff --git a/rust/Makefile b/rust/Makefile
> index 7ea7570e3f17..7fe4cbbd176e 100644
> --- a/rust/Makefile
> +++ b/rust/Makefile
> @@ -410,7 +410,13 @@ BINDGEN_TARGET_x86	:= x86_64-linux-gnu
>  BINDGEN_TARGET_arm64	:= aarch64-linux-gnu
>  BINDGEN_TARGET_arm	:= arm-linux-gnueabi
>  BINDGEN_TARGET_loongarch	:= loongarch64-linux-gnusf
> +
> +ifdef CONFIG_PPC64
> +BINDGEN_TARGET_powerpc	:= powerpc64le-linux-gnu
> +else
>  BINDGEN_TARGET_powerpc	:= powerpc-linux-gnu
> +endif
> +
>  BINDGEN_TARGET_um	:= $(BINDGEN_TARGET_$(SUBARCH))
>  BINDGEN_TARGET		:= $(BINDGEN_TARGET_$(SRCARCH))
>