Re: [PATCH] riscv: Only allow LTO with CMODEL_MEDANY

Re: [PATCH] riscv: Only allow LTO with CMODEL_MEDANY

[Nathan Chancellor]

Ping? This is still getting hit.

On Thu, Jul 10, 2025 at 01:25:26PM -0700, Nathan Chancellor wrote:
> When building with CONFIG_CMODEL_MEDLOW and CONFIG_LTO_CLANG, there is a
> series of errors due to some files being unconditionally compiled with
> '-mcmodel=medany', mismatching with the rest of the kernel built with
> '-mcmodel=medlow':
> 
>   ld.lld: error: Function Import: link error: linking module flags 'Code Model': IDs have conflicting values: 'i32 3' from vmlinux.a(init.o at 899908), and 'i32 1' from vmlinux.a(net-traces.o at 1014628)
> 
> Only allow LTO to be performed when CONFIG_CMODEL_MEDANY is enabled to
> ensure there will be no code model mismatch errors. An alternative
> solution would be disabling LTO for the files with a different code
> model than the main kernel like some specialized areas of the kernel do
> but doing that for individual files is not as sustainable than
> forbidding the combination altogether.
> 
> Cc: stable@vger.kernel.org
> Fixes: 021d23428bdb ("RISC-V: build: Allow LTO to be selected")
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202506290255.KBVM83vZ-lkp@intel.com/
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---
>  arch/riscv/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 36061f4732b7..4eee737a050f 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -68,7 +68,7 @@ config RISCV
>  	select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE
>  	select ARCH_SUPPORTS_HUGETLBFS if MMU
>  	# LLD >= 14: https://github.com/llvm/llvm-project/issues/50505
> -	select ARCH_SUPPORTS_LTO_CLANG if LLD_VERSION >= 140000
> +	select ARCH_SUPPORTS_LTO_CLANG if LLD_VERSION >= 140000 && CMODEL_MEDANY
>  	select ARCH_SUPPORTS_LTO_CLANG_THIN if LLD_VERSION >= 140000
>  	select ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS if 64BIT && MMU
>  	select ARCH_SUPPORTS_PAGE_TABLE_CHECK if MMU
> 
> ---
> base-commit: fda589c286040d9ba2d72a0eaf0a13945fc48026
> change-id: 20250710-riscv-restrict-lto-to-medany-f1b7dd5c9bba
> 
> Best regards,
> --  
> Nathan Chancellor <nathan@kernel.org>
> 

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Re: [PATCH] riscv: Only allow LTO with CMODEL_MEDANY

[Alexandre Ghiti]

Hi Nathan,

On 8/8/25 23:53, Nathan Chancellor wrote:
> Ping? This is still getting hit.


This is the second time your patches do not reach the linux-riscv 
mailing list [1] [2], not even my personal mailbox.

[1] 
https://lore.kernel.org/linux-riscv/?q=riscv%3A+Only+allow+LTO+with+CMODEL_MEDANY 

[2] 
https://lore.kernel.org/linux-riscv/?q=riscv%3A+uaccess%3A+Fix+-Wuninitialized+and+-Wshadow+in+__put_user_nocheck

I don't know what's going on, do you have any idea?

I'll pick this up in my fixes branch.

Thanks,

Alex


>
> On Thu, Jul 10, 2025 at 01:25:26PM -0700, Nathan Chancellor wrote:
>> When building with CONFIG_CMODEL_MEDLOW and CONFIG_LTO_CLANG, there is a
>> series of errors due to some files being unconditionally compiled with
>> '-mcmodel=medany', mismatching with the rest of the kernel built with
>> '-mcmodel=medlow':
>>
>>    ld.lld: error: Function Import: link error: linking module flags 'Code Model': IDs have conflicting values: 'i32 3' from vmlinux.a(init.o at 899908), and 'i32 1' from vmlinux.a(net-traces.o at 1014628)
>>
>> Only allow LTO to be performed when CONFIG_CMODEL_MEDANY is enabled to
>> ensure there will be no code model mismatch errors. An alternative
>> solution would be disabling LTO for the files with a different code
>> model than the main kernel like some specialized areas of the kernel do
>> but doing that for individual files is not as sustainable than
>> forbidding the combination altogether.
>>
>> Cc: stable@vger.kernel.org
>> Fixes: 021d23428bdb ("RISC-V: build: Allow LTO to be selected")
>> Reported-by: kernel test robot <lkp@intel.com>
>> Closes: https://lore.kernel.org/oe-kbuild-all/202506290255.KBVM83vZ-lkp@intel.com/
>> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
>> ---
>>   arch/riscv/Kconfig | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> index 36061f4732b7..4eee737a050f 100644
>> --- a/arch/riscv/Kconfig
>> +++ b/arch/riscv/Kconfig
>> @@ -68,7 +68,7 @@ config RISCV
>>   	select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE
>>   	select ARCH_SUPPORTS_HUGETLBFS if MMU
>>   	# LLD >= 14: https://github.com/llvm/llvm-project/issues/50505
>> -	select ARCH_SUPPORTS_LTO_CLANG if LLD_VERSION >= 140000
>> +	select ARCH_SUPPORTS_LTO_CLANG if LLD_VERSION >= 140000 && CMODEL_MEDANY
>>   	select ARCH_SUPPORTS_LTO_CLANG_THIN if LLD_VERSION >= 140000
>>   	select ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS if 64BIT && MMU
>>   	select ARCH_SUPPORTS_PAGE_TABLE_CHECK if MMU
>>
>> ---
>> base-commit: fda589c286040d9ba2d72a0eaf0a13945fc48026
>> change-id: 20250710-riscv-restrict-lto-to-medany-f1b7dd5c9bba
>>
>> Best regards,
>> --
>> Nathan Chancellor <nathan@kernel.org>
>>
> _______________________________________________
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Re: [PATCH] riscv: Only allow LTO with CMODEL_MEDANY

[Nathan Chancellor]

On Sat, Aug 09, 2025 at 12:45:59PM +0200, Alexandre Ghiti wrote:
> Hi Nathan,
> 
> On 8/8/25 23:53, Nathan Chancellor wrote:
> > Ping? This is still getting hit.
> 
> 
> This is the second time your patches do not reach the linux-riscv mailing
> list [1] [2], not even my personal mailbox.
> 
> [1] https://lore.kernel.org/linux-riscv/?q=riscv%3A+Only+allow+LTO+with+CMODEL_MEDANY
> 
> [2] https://lore.kernel.org/linux-riscv/?q=riscv%3A+uaccess%3A+Fix+-Wuninitialized+and+-Wshadow+in+__put_user_nocheck
> 
> I don't know what's going on, do you have any idea?

Huh, not sure :/ I only use my kernel.org address and nothing about my
configuration or usage has changed plus it seems to have made it to
every other mailing list I sent it to?

https://lore.kernel.org/lkml/20250710-riscv-restrict-lto-to-medany-v1-1-b1dac9871ecf@kernel.org/
https://lore.kernel.org/llvm/20250710-riscv-restrict-lto-to-medany-v1-1-b1dac9871ecf@kernel.org/
https://lore.kernel.org/stable/20250710-riscv-restrict-lto-to-medany-v1-1-b1dac9871ecf@kernel.org/

Next time I have to send a RISC-V patch, I'll look at the archives to
see if it made it there and follow up if not.

> I'll pick this up in my fixes branch.

Great, thanks a lot!

Cheers,
Nathan

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