Currently rust on arm fails to compile due to '-mno-fdpic'. This flag disables a GCC feature that we don't want for kernel builds, so let's skip it as it doesn't apply to Clang.
UPD include/generated/asm-offsets.h CALL scripts/checksyscalls.sh RUSTC L rust/core.o BINDGEN rust/bindings/bindings_generated.rs BINDGEN rust/bindings/bindings_helpers_generated.rs CC rust/helpers/helpers.o Unable to generate bindings: clang diagnosed error: error: unknown argument: '-mno-fdpic' make[2]: *** [rust/Makefile:369: rust/bindings/bindings_helpers_generated.rs] Error 1 make[2]: *** Deleting file 'rust/bindings/bindings_helpers_generated.rs' make[2]: *** Waiting for unfinished jobs.... Unable to generate bindings: clang diagnosed error: error: unknown argument: '-mno-fdpic' make[2]: *** [rust/Makefile:349: rust/bindings/bindings_generated.rs] Error 1 make[2]: *** Deleting file 'rust/bindings/bindings_generated.rs' make[1]: *** [/home/pmos/build/src/linux-next-next-20250521/Makefile:1285: prepare] Error 2 make: *** [Makefile:248: __sub-make] Error 2
Reported-by: Linux Kernel Functional Testing lkft@linaro.org Closes: https://lore.kernel.org/all/CA+G9fYvOanQBYXKSg7C6EU30k8sTRC0JRPJXYu7wWK51w38... Suggested-by: Miguel Ojeda ojeda@kernel.org Tested-by: Rudraksha Gupta guptarud@gmail.com Acked-by: Naresh Kamboju naresh.kamboju@linaro.org Signed-off-by: Rudraksha Gupta guptarud@gmail.com --- Changes in v2: - Fixed patch formatting issues - Link to v1: https://lore.kernel.org/r/20250520-rust-mno-fdpic-arm-fix-v1-1-44e77fe6b2a1@... --- rust/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/rust/Makefile b/rust/Makefile index 3aca903a7d08..f207ba0ed466 100644 --- a/rust/Makefile +++ b/rust/Makefile @@ -273,7 +273,7 @@ bindgen_skip_c_flags := -mno-fp-ret-in-387 -mpreferred-stack-boundary=% \ -fzero-call-used-regs=% -fno-stack-clash-protection \ -fno-inline-functions-called-once -fsanitize=bounds-strict \ -fstrict-flex-arrays=% -fmin-function-alignment=% \ - -fzero-init-padding-bits=% \ + -fzero-init-padding-bits=% -mno-fdpic \ --param=% --param asan-%
# Derived from `scripts/Makefile.clang`.
--- base-commit: a5806cd506af5a7c19bcd596e4708b5c464bfd21 change-id: 20250520-rust-mno-fdpic-arm-fix-940a58bf9433
Best regards,
On Thu, May 22, 2025 at 2:02 PM Rudraksha Gupta guptarud@gmail.com wrote:
Currently rust on arm fails to compile due to '-mno-fdpic'. This flag disables a GCC feature that we don't want for kernel builds, so let's skip it as it doesn't apply to Clang.
UPD include/generated/asm-offsets.h CALL scripts/checksyscalls.sh RUSTC L rust/core.o BINDGEN rust/bindings/bindings_generated.rs BINDGEN rust/bindings/bindings_helpers_generated.rs CC rust/helpers/helpers.o Unable to generate bindings: clang diagnosed error: error: unknown argument: '-mno-fdpic' make[2]: *** [rust/Makefile:369: rust/bindings/bindings_helpers_generated.rs] Error 1 make[2]: *** Deleting file 'rust/bindings/bindings_helpers_generated.rs' make[2]: *** Waiting for unfinished jobs.... Unable to generate bindings: clang diagnosed error: error: unknown argument: '-mno-fdpic' make[2]: *** [rust/Makefile:349: rust/bindings/bindings_generated.rs] Error 1 make[2]: *** Deleting file 'rust/bindings/bindings_generated.rs' make[1]: *** [/home/pmos/build/src/linux-next-next-20250521/Makefile:1285: prepare] Error 2 make: *** [Makefile:248: __sub-make] Error 2Reported-by: Linux Kernel Functional Testing lkft@linaro.org Closes: https://lore.kernel.org/all/CA+G9fYvOanQBYXKSg7C6EU30k8sTRC0JRPJXYu7wWK51w38... Suggested-by: Miguel Ojeda ojeda@kernel.org Tested-by: Rudraksha Gupta guptarud@gmail.com Acked-by: Naresh Kamboju naresh.kamboju@linaro.org Signed-off-by: Rudraksha Gupta guptarud@gmail.com
Thanks for sending a v2! I was going to fix it myself, but this is even better :)
By the way, submitting a patch typically requires / generally implies that you actually tested it, so your own Tested-by is usually not provided.
Cheers, Miguel
Thanks for sending a v2! I was going to fix it myself, but this is even better :)
By the way, submitting a patch typically requires / generally implies that you actually tested it, so your own Tested-by is usually not provided.
Thanks! :D Happy to send in a v3 if needed
Rudraksha
Cheers, Miguel
On Thu, May 22, 2025 at 3:27 PM Rudraksha Gupta guptarud@gmail.com wrote:
Thanks! :D Happy to send in a v3 if needed
No worries, I will apply this one :)
I will remove the tag, unless you want it there for some reason (e.g. because you want to point out some extra testing that goes beyond what would normally be done).
Thanks!
Cheers, Miguel
On Thu, May 22, 2025 at 2:02 PM Rudraksha Gupta guptarud@gmail.com wrote:
Currently rust on arm fails to compile due to '-mno-fdpic'. This flag disables a GCC feature that we don't want for kernel builds, so let's skip it as it doesn't apply to Clang.
UPD include/generated/asm-offsets.h CALL scripts/checksyscalls.sh RUSTC L rust/core.o BINDGEN rust/bindings/bindings_generated.rs BINDGEN rust/bindings/bindings_helpers_generated.rs CC rust/helpers/helpers.o Unable to generate bindings: clang diagnosed error: error: unknown argument: '-mno-fdpic' make[2]: *** [rust/Makefile:369: rust/bindings/bindings_helpers_generated.rs] Error 1 make[2]: *** Deleting file 'rust/bindings/bindings_helpers_generated.rs' make[2]: *** Waiting for unfinished jobs.... Unable to generate bindings: clang diagnosed error: error: unknown argument: '-mno-fdpic' make[2]: *** [rust/Makefile:349: rust/bindings/bindings_generated.rs] Error 1 make[2]: *** Deleting file 'rust/bindings/bindings_generated.rs' make[1]: *** [/home/pmos/build/src/linux-next-next-20250521/Makefile:1285: prepare] Error 2 make: *** [Makefile:248: __sub-make] Error 2Reported-by: Linux Kernel Functional Testing lkft@linaro.org Closes: https://lore.kernel.org/all/CA+G9fYvOanQBYXKSg7C6EU30k8sTRC0JRPJXYu7wWK51w38... Suggested-by: Miguel Ojeda ojeda@kernel.org Tested-by: Rudraksha Gupta guptarud@gmail.com Acked-by: Naresh Kamboju naresh.kamboju@linaro.org Signed-off-by: Rudraksha Gupta guptarud@gmail.com
Applied to `rust-next` -- thanks everyone!
[ Naresh provided the draft diff [1].
Ben explained [2]:
FDPIC is only relevant with no-MMU targets, and then only for userspace. When configured for the arm-*-uclinuxfdpiceabi target, GCC enables FDPIC by default to facilitate compiling userspace programs. FDPIC is never used for the kernel, and we pass -mno-fdpic when building the kernel to override the default and make sure FDPIC is disabled.
and [3]:
-mno-fdpic disables a GCC feature that we don't want for kernel builds. clang does not support this feature, so it always behaves as though -mno-fdpic is passed. Therefore, it should be fine to mix the two, at least as far as FDPIC is concerned.
[1] https://lore.kernel.org/rust-for-linux/CA+G9fYt4otQK4pHv8pJBW9e28yHSGCDncKqu... [2] https://lore.kernel.org/rust-for-linux/aAKrq2InExQk7f_k@dell-precision-5540/ [3] https://lore.kernel.org/rust-for-linux/aAo_F_UP1Gd4jHlZ@dell-precision-5540/
- Miguel ]
[ Reworded title. - Miguel ]
Cheers, Miguel
-
Miguel Ojeda -
Rudraksha Gupta