[PATCH v1] RISC-V: disallow gcc + rust builds

[Alexandre Ghiti]

On 09/10/2024 09:46, Alexandre Ghiti wrote:
> Hi Conor,
>
> On 01/10/2024 13:28, Conor Dooley wrote:
>> From: Conor Dooley <conor.dooley at microchip.com>
>>
>> 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
>
>
> I have just added "[2]" here as it seemed to be missing.
>
> Thanks,
>
> Alex
>
>
>> , 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: 70a57b247251a ("RISC-V: enable building 64-bit kernels with 
>> rust support")


I also fixed the Fixes tag ^, it contains 13 characters instead of 12 
and added a cc: stable tag.


>> Reported-by: Jason Montleon <jmontleo at redhat.com>


And I moved this tag above the Closes tag.

Thanks,

Alex


>> Signed-off-by: Conor Dooley <conor.dooley at microchip.com>
>> ---
>>
>> Palmer, this is yours to take.
>>
>> CC: jmontleo at redhat.com
>> CC: ojeda at kernel.org
>> CC: alex.gaynor at gmail.com
>> CC: boqun.feng at gmail.com
>> CC: gary at garyguo.net
>> CC: bjorn3_gh at protonmail.com
>> CC: benno.lossin at proton.me
>> CC: a.hindborg at kernel.org
>> CC: aliceryhl at google.com
>> CC: paul.walmsley at sifive.com
>> CC: palmer at dabbelt.com
>> CC: nathan at kernel.org
>> CC: ndesaulniers at google.com
>> CC: morbo at google.com
>> CC: justinstitt at google.com
>> CC: rust-for-linux at vger.kernel.org
>> CC: linux-riscv at lists.infradead.org
>> CC: llvm at lists.linux.dev
>> ---
>>   Documentation/rust/arch-support.rst | 2 +-
>>   arch/riscv/Kconfig                  | 2 +-
>>   2 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/rust/arch-support.rst 
>> b/Documentation/rust/arch-support.rst
>> index 750ff371570a0..54be7ddf3e57a 100644
>> --- a/Documentation/rust/arch-support.rst
>> +++ b/Documentation/rust/arch-support.rst
>> @@ -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.
>>   =============  ================ 
>> ==============================================
>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> index 22dc5ea4196ce..76843584960c2 100644
>> --- a/arch/riscv/Kconfig
>> +++ b/arch/riscv/Kconfig
>> @@ -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
>
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