Commit 33549fcf37ec ("RISC-V: disallow gcc + rust builds") disabled GCC
+ Rust builds for RISC-V due to differences in extension handling
compared to LLVM. This commit enables GCC + Rust builds again.
Add `bindgen-option` conditions for the availability of libclang to the
RISC-V extension Kconfig symbols that depend on the `cc-option`
function.
For Zicsr/Zifencei special handling, since LLVM/Clang always enables
these two extensions, either don't pass them to `-march`, or pass them
explicitly and Rust bindgen libclang must recognize them.
Clang does not support `-mno-riscv-attribute` flag, filter it out to
resolve error: unknown argument: '-mno-riscv-attribute'.
Define `BINDGEN_TARGET_riscv` to pass the target triplet to Rust bindgen
libclang for RISC-V to resolve error: unsupported argument 'medany' to
option '-mcmodel=' for target 'unknown'.
Update the documentation, GCC + Rust builds for RISC-V are now
maintained.
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Asuna Yang <xinrui.riscv@isrc.iscas.ac.cn>
---
Documentation/rust/arch-support.rst | 2 +-
arch/riscv/Kconfig | 35 ++++++++++++++++++++++++++++++++++-
rust/Makefile | 3 ++-
scripts/Makefile.rust | 1 +
4 files changed, 38 insertions(+), 3 deletions(-)
diff --git a/Documentation/rust/arch-support.rst b/Documentation/rust/arch-support.rst
index 6e6a515d0899..5282e0e174e8 100644
--- a/Documentation/rust/arch-support.rst
+++ b/Documentation/rust/arch-support.rst
@@ -18,7 +18,7 @@ Architecture Level of support Constraints
``arm`` Maintained ARMv7 Little Endian only.
``arm64`` Maintained Little Endian only.
``loongarch`` Maintained \-
-``riscv`` Maintained ``riscv64`` and LLVM/Clang only.
+``riscv`` Maintained ``riscv64`` only.
``um`` Maintained \-
``x86`` Maintained ``x86_64`` only.
============= ================ ==============================================
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 6b39f37f769a..c869ee07117e 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -195,7 +195,7 @@ config RISCV
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_RETHOOK if !XIP_KERNEL
select HAVE_RSEQ
- select HAVE_RUST if RUSTC_SUPPORTS_RISCV && CC_IS_CLANG
+ select HAVE_RUST if RUSTC_SUPPORTS_RISCV && TOOLCHAIN_MATCHES_ZICSR_ZIFENCEI
select HAVE_SAMPLE_FTRACE_DIRECT
select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
select HAVE_STACKPROTECTOR
@@ -619,6 +619,8 @@ config TOOLCHAIN_HAS_V
depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32imv)
depends on LD_IS_LLD || LD_VERSION >= 23800
depends on AS_HAS_OPTION_ARCH
+ depends on !RUST || !64BIT || $(bindgen-backend-option,-mabi=lp64 -march=rv64imv)
+ depends on !RUST || !32BIT || $(bindgen-backend-option,-mabi=ilp32 -march=rv32imv)
config RISCV_ISA_V
bool "Vector extension support"
@@ -683,6 +685,8 @@ config TOOLCHAIN_HAS_ZABHA
depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zabha)
depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zabha)
depends on AS_HAS_OPTION_ARCH
+ depends on !RUST || !64BIT || $(bindgen-backend-option,-mabi=lp64 -march=rv64ima_zabha)
+ depends on !RUST || !32BIT || $(bindgen-backend-option,-mabi=ilp32 -march=rv32ima_zabha)
config RISCV_ISA_ZABHA
bool "Zabha extension support for atomic byte/halfword operations"
@@ -701,6 +705,8 @@ config TOOLCHAIN_HAS_ZACAS
depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zacas)
depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zacas)
depends on AS_HAS_OPTION_ARCH
+ depends on !RUST || !64BIT || $(bindgen-backend-option,-mabi=lp64 -march=rv64ima_zacas)
+ depends on !RUST || !32BIT || $(bindgen-backend-option,-mabi=ilp32 -march=rv32ima_zacas)
config RISCV_ISA_ZACAS
bool "Zacas extension support for atomic CAS"
@@ -719,6 +725,8 @@ config TOOLCHAIN_HAS_ZBB
depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zbb)
depends on LD_IS_LLD || LD_VERSION >= 23900
depends on AS_HAS_OPTION_ARCH
+ depends on !RUST || !64BIT || $(bindgen-backend-option,-mabi=lp64 -march=rv64ima_zbb)
+ depends on !RUST || !32BIT || $(bindgen-backend-option,-mabi=ilp32 -march=rv32ima_zbb)
# This symbol indicates that the toolchain supports all v1.0 vector crypto
# extensions, including Zvk*, Zvbb, and Zvbc. LLVM added all of these at once.
@@ -734,6 +742,8 @@ config TOOLCHAIN_HAS_ZBA
depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zba)
depends on LD_IS_LLD || LD_VERSION >= 23900
depends on AS_HAS_OPTION_ARCH
+ depends on !RUST || !64BIT || $(bindgen-backend-option,-mabi=lp64 -march=rv64ima_zba)
+ depends on !RUST || !32BIT || $(bindgen-backend-option,-mabi=ilp32 -march=rv32ima_zba)
config RISCV_ISA_ZBA
bool "Zba extension support for bit manipulation instructions"
@@ -769,6 +779,8 @@ config TOOLCHAIN_HAS_ZBC
depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zbc)
depends on LD_IS_LLD || LD_VERSION >= 23900
depends on AS_HAS_OPTION_ARCH
+ depends on !RUST || !64BIT || $(bindgen-backend-option,-mabi=lp64 -march=rv64ima_zbc)
+ depends on !RUST || !32BIT || $(bindgen-backend-option,-mabi=ilp32 -march=rv32ima_zbc)
config RISCV_ISA_ZBC
bool "Zbc extension support for carry-less multiplication instructions"
@@ -792,6 +804,8 @@ config TOOLCHAIN_HAS_ZBKB
depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zbkb)
depends on LD_IS_LLD || LD_VERSION >= 23900
depends on AS_HAS_OPTION_ARCH
+ depends on !RUST || !64BIT || $(bindgen-backend-option,-mabi=lp64 -march=rv64ima_zbkb)
+ depends on !RUST || !32BIT || $(bindgen-backend-option,-mabi=ilp32 -march=rv32ima_zbkb)
config RISCV_ISA_ZBKB
bool "Zbkb extension support for bit manipulation instructions"
@@ -893,6 +907,25 @@ config TOOLCHAIN_NEEDS_OLD_ISA_SPEC
versions of clang and GCC to be passed to GAS, which has the same result
as passing zicsr and zifencei to -march.
+config RUST_BINDGEN_HAS_ZICSR_ZIFENCEI
+ def_bool y
+ depends on !64BIT || $(bindgen-backend-option,-mabi=lp64 -march=rv64ima_zicsr_zifencei)
+ depends on !32BIT || $(bindgen-backend-option,-mabi=ilp32 -march=rv32ima_zicsr_zifencei)
+
+config TOOLCHAIN_MATCHES_ZICSR_ZIFENCEI
+ def_bool y
+ # https://github.com/llvm/llvm-project/commit/22e199e6afb1263c943c0c0d4498694e15bf8a16
+ depends on TOOLCHAIN_NEEDS_OLD_ISA_SPEC || !TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI || RUST_BINDGEN_HAS_ZICSR_ZIFENCEI
+ help
+ LLVM/Clang >= 17.0.0 starts recognizing Zicsr/Zifencei in -march, passing
+ them to -march doesn't generate an error anymore, and passing them or not
+ doesn't have any real difference, it still follows ISA before version
+ 20190608 - Zicsr/Zifencei are included in base ISA.
+
+ The current latest version of LLVM/Clang still does not require explicit
+ Zicsr/Zifencei to enable these two extensions, Clang just accepts them in
+ -march and then silently ignores them.
+
config FPU
bool "FPU support"
default y
diff --git a/rust/Makefile b/rust/Makefile
index 37b4205afb70..d8b6a570cb84 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -383,7 +383,8 @@ bindgen_skip_c_flags := -mno-fp-ret-in-387 -mpreferred-stack-boundary=% \
-fno-inline-functions-called-once -fsanitize=bounds-strict \
-fstrict-flex-arrays=% -fmin-function-alignment=% \
-fzero-init-padding-bits=% -mno-fdpic \
- --param=% --param asan-% -fno-isolate-erroneous-paths-dereference
+ --param=% --param asan-% -fno-isolate-erroneous-paths-dereference \
+ -mno-riscv-attribute
# Because scripts/Makefile.rust is included regardless of whether Rust is enabled,
# we perform this check here to avoid breaking targets that do not yet support Rust builds.
diff --git a/scripts/Makefile.rust b/scripts/Makefile.rust
index 5c12b4b8c8b6..bfdad4a0a3ce 100644
--- a/scripts/Makefile.rust
+++ b/scripts/Makefile.rust
@@ -3,6 +3,7 @@ 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
+BINDGEN_TARGET_riscv := riscv64-linux-gnu
BINDGEN_TARGET_um := $(BINDGEN_TARGET_$(SUBARCH))
BINDGEN_TARGET := $(BINDGEN_TARGET_$(SRCARCH))
--
2.51.1Asuna Yang <xinrui.riscv@isrc.iscas.ac.cn> writes:
> Commit 33549fcf37ec ("RISC-V: disallow gcc + rust builds") disabled GCC
> + Rust builds for RISC-V due to differences in extension handling
> compared to LLVM. This commit enables GCC + Rust builds again.
>
> Add `bindgen-option` conditions for the availability of libclang to the
> RISC-V extension Kconfig symbols that depend on the `cc-option`
> function.
>
> For Zicsr/Zifencei special handling, since LLVM/Clang always enables
> these two extensions, either don't pass them to `-march`, or pass them
> explicitly and Rust bindgen libclang must recognize them.
>
> Clang does not support `-mno-riscv-attribute` flag, filter it out to
> resolve error: unknown argument: '-mno-riscv-attribute'.
>
> Define `BINDGEN_TARGET_riscv` to pass the target triplet to Rust bindgen
> libclang for RISC-V to resolve error: unsupported argument 'medany' to
> option '-mcmodel=' for target 'unknown'.
>
> Update the documentation, GCC + Rust builds for RISC-V are now
> maintained.
>
> Acked-by: Miguel Ojeda <ojeda@kernel.org>
> Signed-off-by: Asuna Yang <xinrui.riscv@isrc.iscas.ac.cn>
> ---
> Documentation/rust/arch-support.rst | 2 +-
> arch/riscv/Kconfig | 35 ++++++++++++++++++++++++++++++++++-
> rust/Makefile | 3 ++-
> scripts/Makefile.rust | 1 +
> 4 files changed, 38 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/rust/arch-support.rst b/Documentation/rust/arch-support.rst
> index 6e6a515d0899..5282e0e174e8 100644
> --- a/Documentation/rust/arch-support.rst
> +++ b/Documentation/rust/arch-support.rst
> @@ -18,7 +18,7 @@ Architecture Level of support Constraints
> ``arm`` Maintained ARMv7 Little Endian only.
> ``arm64`` Maintained Little Endian only.
> ``loongarch`` Maintained \-
> -``riscv`` Maintained ``riscv64`` and LLVM/Clang only.
> +``riscv`` Maintained ``riscv64`` only.
> ``um`` Maintained \-
> ``x86`` Maintained ``x86_64`` only.
> ============= ================ ==============================================
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 6b39f37f769a..c869ee07117e 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -195,7 +195,7 @@ config RISCV
> select HAVE_REGS_AND_STACK_ACCESS_API
> select HAVE_RETHOOK if !XIP_KERNEL
> select HAVE_RSEQ
> - select HAVE_RUST if RUSTC_SUPPORTS_RISCV && CC_IS_CLANG
> + select HAVE_RUST if RUSTC_SUPPORTS_RISCV && TOOLCHAIN_MATCHES_ZICSR_ZIFENCEI
> select HAVE_SAMPLE_FTRACE_DIRECT
> select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
> select HAVE_STACKPROTECTOR
> @@ -619,6 +619,8 @@ config TOOLCHAIN_HAS_V
> depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32imv)
> depends on LD_IS_LLD || LD_VERSION >= 23800
> depends on AS_HAS_OPTION_ARCH
> + depends on !RUST || !64BIT || $(bindgen-backend-option,-mabi=lp64 -march=rv64imv)
> + depends on !RUST || !32BIT || $(bindgen-backend-option,-mabi=ilp32 -march=rv32imv)
Hi Asuna!
I'm under the impression that the `!RUST ||` guard here doesn't
actually prevent the `$(bindgen-backend-option,...)` call from being
executed. `$(...)` shell expansions should happen during the textual
substitution phase, before symbol dependency evaluation occurs, check
documentation at kconfig-macro-language.rst lines 228-229.
I did this test:
$ cat /tmp/fake_bindgen
#!/bin/bash
echo "[BINDGEN INVOKED] $(date '+%H:%M:%S') args: $@" >> /tmp/bindgen_calls.log
# Call real bindgen
exec /home/charmitro/.cargo/bin/bindgen "$@"
$ make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- BINDGEN=/tmp/fake_bindgen defconfig
HOSTCC scripts/basic/fixdep
...
*** Default configuration is based on 'defconfig'
#
# configuration written to .config
#
$ linux git:(master) rg CONFIG_RUST .config
...
283:# CONFIG_RUST is not set
...
$ cat /tmp/bindgen_calls.log
[BINDGEN INVOKED] 15:44:44 args: --version workaround-for-0.69.0
[BINDGEN INVOKED] 15:44:44 args: ./scripts/rust_is_available_bindgen_libclang.h
[BINDGEN INVOKED] 15:44:44 args: --version workaround-for-0.69.0
[BINDGEN INVOKED] 15:44:44 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=lp64 -march=rv64imv
[BINDGEN INVOKED] 15:44:44 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=ilp32 -march=rv32imv
[BINDGEN INVOKED] 15:44:44 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=lp64 -march=rv64ima_zabha
[BINDGEN INVOKED] 15:44:44 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=ilp32 -march=rv32ima_zabha
[BINDGEN INVOKED] 15:44:45 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=lp64 -march=rv64ima_zacas
[BINDGEN INVOKED] 15:44:45 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=ilp32 -march=rv32ima_zacas
[BINDGEN INVOKED] 15:44:45 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=lp64 -march=rv64ima_zbb
[BINDGEN INVOKED] 15:44:45 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=ilp32 -march=rv32ima_zbb
[BINDGEN INVOKED] 15:44:45 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=lp64 -march=rv64ima_zba
[BINDGEN INVOKED] 15:44:45 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=ilp32 -march=rv32ima_zba
[BINDGEN INVOKED] 15:44:45 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=lp64 -march=rv64ima_zbc
[BINDGEN INVOKED] 15:44:46 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=ilp32 -march=rv32ima_zbc
[BINDGEN INVOKED] 15:44:46 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=lp64 -march=rv64ima_zbkb
[BINDGEN INVOKED] 15:44:46 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=ilp32 -march=rv32ima_zbkb
[BINDGEN INVOKED] 15:44:46 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=lp64 -march=rv64ima_zicsr_zifencei
[BINDGEN INVOKED] 15:44:46 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=ilp32 -march=rv32ima_zicsr_zifencei
So, CONFIG_RUST not set, yet bindgen was invoked. Not sure if that is
intentional though.
Cheers,
C. Mitrodimas
>
> config RISCV_ISA_V
> bool "Vector extension support"
> @@ -683,6 +685,8 @@ config TOOLCHAIN_HAS_ZABHA
> depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zabha)
> depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zabha)
> depends on AS_HAS_OPTION_ARCH
> + depends on !RUST || !64BIT || $(bindgen-backend-option,-mabi=lp64 -march=rv64ima_zabha)
> + depends on !RUST || !32BIT || $(bindgen-backend-option,-mabi=ilp32 -march=rv32ima_zabha)
>
> config RISCV_ISA_ZABHA
> bool "Zabha extension support for atomic byte/halfword operations"
> @@ -701,6 +705,8 @@ config TOOLCHAIN_HAS_ZACAS
> depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zacas)
> depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zacas)
> depends on AS_HAS_OPTION_ARCH
> + depends on !RUST || !64BIT || $(bindgen-backend-option,-mabi=lp64 -march=rv64ima_zacas)
> + depends on !RUST || !32BIT || $(bindgen-backend-option,-mabi=ilp32 -march=rv32ima_zacas)
>
> config RISCV_ISA_ZACAS
> bool "Zacas extension support for atomic CAS"
> @@ -719,6 +725,8 @@ config TOOLCHAIN_HAS_ZBB
> depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zbb)
> depends on LD_IS_LLD || LD_VERSION >= 23900
> depends on AS_HAS_OPTION_ARCH
> + depends on !RUST || !64BIT || $(bindgen-backend-option,-mabi=lp64 -march=rv64ima_zbb)
> + depends on !RUST || !32BIT || $(bindgen-backend-option,-mabi=ilp32 -march=rv32ima_zbb)
>
> # This symbol indicates that the toolchain supports all v1.0 vector crypto
> # extensions, including Zvk*, Zvbb, and Zvbc. LLVM added all of these at once.
> @@ -734,6 +742,8 @@ config TOOLCHAIN_HAS_ZBA
> depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zba)
> depends on LD_IS_LLD || LD_VERSION >= 23900
> depends on AS_HAS_OPTION_ARCH
> + depends on !RUST || !64BIT || $(bindgen-backend-option,-mabi=lp64 -march=rv64ima_zba)
> + depends on !RUST || !32BIT || $(bindgen-backend-option,-mabi=ilp32 -march=rv32ima_zba)
>
> config RISCV_ISA_ZBA
> bool "Zba extension support for bit manipulation instructions"
> @@ -769,6 +779,8 @@ config TOOLCHAIN_HAS_ZBC
> depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zbc)
> depends on LD_IS_LLD || LD_VERSION >= 23900
> depends on AS_HAS_OPTION_ARCH
> + depends on !RUST || !64BIT || $(bindgen-backend-option,-mabi=lp64 -march=rv64ima_zbc)
> + depends on !RUST || !32BIT || $(bindgen-backend-option,-mabi=ilp32 -march=rv32ima_zbc)
>
> config RISCV_ISA_ZBC
> bool "Zbc extension support for carry-less multiplication instructions"
> @@ -792,6 +804,8 @@ config TOOLCHAIN_HAS_ZBKB
> depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zbkb)
> depends on LD_IS_LLD || LD_VERSION >= 23900
> depends on AS_HAS_OPTION_ARCH
> + depends on !RUST || !64BIT || $(bindgen-backend-option,-mabi=lp64 -march=rv64ima_zbkb)
> + depends on !RUST || !32BIT || $(bindgen-backend-option,-mabi=ilp32 -march=rv32ima_zbkb)
>
> config RISCV_ISA_ZBKB
> bool "Zbkb extension support for bit manipulation instructions"
> @@ -893,6 +907,25 @@ config TOOLCHAIN_NEEDS_OLD_ISA_SPEC
> versions of clang and GCC to be passed to GAS, which has the same result
> as passing zicsr and zifencei to -march.
>
> +config RUST_BINDGEN_HAS_ZICSR_ZIFENCEI
> + def_bool y
> + depends on !64BIT || $(bindgen-backend-option,-mabi=lp64 -march=rv64ima_zicsr_zifencei)
> + depends on !32BIT || $(bindgen-backend-option,-mabi=ilp32 -march=rv32ima_zicsr_zifencei)
> +
> +config TOOLCHAIN_MATCHES_ZICSR_ZIFENCEI
> + def_bool y
> + # https://github.com/llvm/llvm-project/commit/22e199e6afb1263c943c0c0d4498694e15bf8a16
> + depends on TOOLCHAIN_NEEDS_OLD_ISA_SPEC || !TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI || RUST_BINDGEN_HAS_ZICSR_ZIFENCEI
> + help
> + LLVM/Clang >= 17.0.0 starts recognizing Zicsr/Zifencei in -march, passing
> + them to -march doesn't generate an error anymore, and passing them or not
> + doesn't have any real difference, it still follows ISA before version
> + 20190608 - Zicsr/Zifencei are included in base ISA.
> +
> + The current latest version of LLVM/Clang still does not require explicit
> + Zicsr/Zifencei to enable these two extensions, Clang just accepts them in
> + -march and then silently ignores them.
> +
> config FPU
> bool "FPU support"
> default y
> diff --git a/rust/Makefile b/rust/Makefile
> index 37b4205afb70..d8b6a570cb84 100644
> --- a/rust/Makefile
> +++ b/rust/Makefile
> @@ -383,7 +383,8 @@ bindgen_skip_c_flags := -mno-fp-ret-in-387 -mpreferred-stack-boundary=% \
> -fno-inline-functions-called-once -fsanitize=bounds-strict \
> -fstrict-flex-arrays=% -fmin-function-alignment=% \
> -fzero-init-padding-bits=% -mno-fdpic \
> - --param=% --param asan-% -fno-isolate-erroneous-paths-dereference
> + --param=% --param asan-% -fno-isolate-erroneous-paths-dereference \
> + -mno-riscv-attribute
>
> # Because scripts/Makefile.rust is included regardless of whether Rust is enabled,
> # we perform this check here to avoid breaking targets that do not yet support Rust builds.
> diff --git a/scripts/Makefile.rust b/scripts/Makefile.rust
> index 5c12b4b8c8b6..bfdad4a0a3ce 100644
> --- a/scripts/Makefile.rust
> +++ b/scripts/Makefile.rust
> @@ -3,6 +3,7 @@ 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
> +BINDGEN_TARGET_riscv := riscv64-linux-gnu
> BINDGEN_TARGET_um := $(BINDGEN_TARGET_$(SUBARCH))
> BINDGEN_TARGET := $(BINDGEN_TARGET_$(SRCARCH))
On 1/29/26 21:49, Charalampos Mitrodimas wrote: > I'm under the impression that the `!RUST ||` guard here doesn't > actually prevent the `$(bindgen-backend-option,...)` call from being > executed. `$(...)` shell expansions should happen during the textual > substitution phase, before symbol dependency evaluation occurs, check > documentation at kconfig-macro-language.rst lines 228-229. I suppose this is unavoidable if we decide to probe options rather than rely on version numbers. Similar issue also occurs in `cc-option`, for example: depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64imv) depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32imv) For 64-bit builds, `-march=rv32imv` will still be probed; for 32-bit builds, `-march=rv64imv` will still be probed. I agree with Nathan that this trivial waste is worth it for the sake of simplicity. Best regards, Asuna
Asuna Yang <xinrui.riscv@isrc.iscas.ac.cn> writes: > On 1/29/26 21:49, Charalampos Mitrodimas wrote: > >> I'm under the impression that the `!RUST ||` guard here doesn't >> actually prevent the `$(bindgen-backend-option,...)` call from being >> executed. `$(...)` shell expansions should happen during the textual >> substitution phase, before symbol dependency evaluation occurs, check >> documentation at kconfig-macro-language.rst lines 228-229. > > I suppose this is unavoidable if we decide to probe options rather > than rely on version numbers. > > Similar issue also occurs in `cc-option`, for example: > > depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64imv) > depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32imv) > > For 64-bit builds, `-march=rv32imv` will still be probed; for 32-bit > builds, `-march=rv64imv` will still be probed. > > I agree with Nathan that this trivial waste is worth it for the sake > of simplicity. Understood. Seems not worth it at all. > > Best regards, > Asuna
On Thu, Jan 29, 2026 at 01:49:56PM +0000, Charalampos Mitrodimas wrote:
> I'm under the impression that the `!RUST ||` guard here doesn't
> actually prevent the `$(bindgen-backend-option,...)` call from being
> executed. `$(...)` shell expansions should happen during the textual
> substitution phase, before symbol dependency evaluation occurs, check
> documentation at kconfig-macro-language.rst lines 228-229.
>
> I did this test:
> $ cat /tmp/fake_bindgen
> #!/bin/bash
> echo "[BINDGEN INVOKED] $(date '+%H:%M:%S') args: $@" >> /tmp/bindgen_calls.log
> # Call real bindgen
> exec /home/charmitro/.cargo/bin/bindgen "$@"
>
> $ make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- BINDGEN=/tmp/fake_bindgen defconfig
> HOSTCC scripts/basic/fixdep
> ...
> *** Default configuration is based on 'defconfig'
> #
> # configuration written to .config
> #
>
> $ linux git:(master) rg CONFIG_RUST .config
> ...
> 283:# CONFIG_RUST is not set
> ...
>
> $ cat /tmp/bindgen_calls.log
> [BINDGEN INVOKED] 15:44:44 args: --version workaround-for-0.69.0
> [BINDGEN INVOKED] 15:44:44 args: ./scripts/rust_is_available_bindgen_libclang.h
> [BINDGEN INVOKED] 15:44:44 args: --version workaround-for-0.69.0
> [BINDGEN INVOKED] 15:44:44 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=lp64 -march=rv64imv
> [BINDGEN INVOKED] 15:44:44 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=ilp32 -march=rv32imv
> [BINDGEN INVOKED] 15:44:44 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=lp64 -march=rv64ima_zabha
> [BINDGEN INVOKED] 15:44:44 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=ilp32 -march=rv32ima_zabha
> [BINDGEN INVOKED] 15:44:45 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=lp64 -march=rv64ima_zacas
> [BINDGEN INVOKED] 15:44:45 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=ilp32 -march=rv32ima_zacas
> [BINDGEN INVOKED] 15:44:45 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=lp64 -march=rv64ima_zbb
> [BINDGEN INVOKED] 15:44:45 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=ilp32 -march=rv32ima_zbb
> [BINDGEN INVOKED] 15:44:45 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=lp64 -march=rv64ima_zba
> [BINDGEN INVOKED] 15:44:45 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=ilp32 -march=rv32ima_zba
> [BINDGEN INVOKED] 15:44:45 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=lp64 -march=rv64ima_zbc
> [BINDGEN INVOKED] 15:44:46 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=ilp32 -march=rv32ima_zbc
> [BINDGEN INVOKED] 15:44:46 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=lp64 -march=rv64ima_zbkb
> [BINDGEN INVOKED] 15:44:46 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=ilp32 -march=rv32ima_zbkb
> [BINDGEN INVOKED] 15:44:46 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=lp64 -march=rv64ima_zicsr_zifencei
> [BINDGEN INVOKED] 15:44:46 args: /dev/null -- -x c --target=riscv64-linux-gnu -mabi=ilp32 -march=rv32ima_zicsr_zifencei
>
> So, CONFIG_RUST not set, yet bindgen was invoked. Not sure if that is
> intentional though.
While I have only recently adopted Kconfig, the section you pointed to
in kconfig-macro-language.rst makes it seem like this is expected. I
read that to mean all shell commands are going to be evaluated and
effectively turned into "y" and "n" before dependencies are evaluated.
You can test this with something like:
if RUST
config RUST_FOOBAR
def_bool $(bindgen-backend-option,-obviously-not-supported)
endif
added in init/Kconfig and running your fake bindgen.
While this is obviously a little wasteful, I suspect this drastically
simplifies the shell commands part of Kconfig for no change in runtime
behavior. The way that the dependency is currently written ensures that
either the result of bindgen-backend-option matters for the sake of
saying an extension is fully supported by the toolchain (when Rust is
enabled) or it does not matter (because Rust is not enabled).
Cheers,
Nathan
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