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RISC-V: disallow gcc + rust builds

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During the discussion before supporting rust on riscv, it was decided
not to support gcc yet, due to differences in extension handling
compared to llvm (only the version of libclang matching the c compiler
is supported). Recently Jason Montleon reported [1] that building with
gcc caused build issues, due to unsupported arguments being passed to
libclang. After some discussion between myself and Miguel, it is better
to disable gcc + rust builds to match the original intent, and
subsequently support it when an appropriate set of extensions can be
deduced from the version of libclang.

Closes: https://lore.kernel.org/all/20240917000848.720765-2-jmontleo@redhat.com/ [1]
Link: https://lore.kernel.org/all/20240926-battering-revolt-6c6a7827413e@spud/ [2]
Fixes: 70a57b2472 ("RISC-V: enable building 64-bit kernels with rust support")
Cc: stable@vger.kernel.org
Reported-by: Jason Montleon <jmontleo@redhat.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20241001-playlist-deceiving-16ece2f440f5@spud
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Conor Dooley 2024-10-01 12:28:13 +01:00 committed by Palmer Dabbelt
parent afedc3126e
commit 33549fcf37
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2 changed files with 2 additions and 2 deletions
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2
Documentation/rust/arch-support.rst
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@ -17,7 +17,7 @@ Architecture Level of support Constraints
============= ================ ==============================================
``arm64`` Maintained Little Endian only.
``loongarch`` Maintained \-
``riscv`` Maintained ``riscv64`` only.
``riscv`` Maintained ``riscv64`` and LLVM/Clang only.
``um`` Maintained \-
``x86`` Maintained ``x86_64`` only.
============= ================ ==============================================

2
arch/riscv/Kconfig
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@ -177,7 +177,7 @@ 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
select HAVE_RUST if RUSTC_SUPPORTS_RISCV && CC_IS_CLANG
select HAVE_SAMPLE_FTRACE_DIRECT
select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
select HAVE_STACKPROTECTOR