linux-kernel - Re: [PATCH 07/10] riscv: Remove version check for LTO

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Message-ID: <8078e385-e08e-40a5-b6df-31c0b5be8f43@ghiti.fr>
Date: Wed, 20 Aug 2025 09:23:08 +0200
From: Alexandre Ghiti <alex@...ti.fr>
To: Nathan Chancellor <nathan@...nel.org>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: Arnd Bergmann <arnd@...db.de>, Kees Cook <kees@...nel.org>,
 Nick Desaulniers <nick.desaulniers+lkml@...il.com>,
 Bill Wendling <morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>,
 linux-kernel@...r.kernel.org, llvm@...ts.linux.dev, patches@...ts.linux.dev,
 Palmer Dabbelt <palmer@...belt.com>, linux-riscv@...ts.infradead.org
Subject: Re: [PATCH 07/10] riscv: Remove version check for LTO_CLANG selects

Hi Nathan,

On 8/18/25 20:57, Nathan Chancellor wrote:
> Now that the minimum supported version of LLVM for building the kernel
> has been bumped to 15.0.0, there is no need to check the LLD version
> before selecting ARCH_SUPPORTS_LTO_CLANG{,_THIN} because it will always
> be true.
>
> Signed-off-by: Nathan Chancellor <nathan@...nel.org>
> ---
> Cc: Palmer Dabbelt <palmer@...belt.com>
> Cc: Alexandre Ghiti <alex@...ti.fr>
> Cc: linux-riscv@...ts.infradead.org
>
> Small note, this will conflict with
> https://lore.kernel.org/20250710-riscv-restrict-lto-to-medany-v1-1-b1dac9871ecf@kernel.org/
> but I think it is simple enough to deal with.


FYI, I'll send this patch for some 6.17-rcX.


> ---
>   arch/riscv/Kconfig | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index a4b233a0659e..1d53bf02d0fa 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -64,9 +64,8 @@ config RISCV
>   	select ARCH_SUPPORTS_DEBUG_PAGEALLOC if MMU
>   	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_THIN if LLD_VERSION >= 140000
> +	select ARCH_SUPPORTS_LTO_CLANG
> +	select ARCH_SUPPORTS_LTO_CLANG_THIN
>   	select ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS if 64BIT && MMU
>   	select ARCH_SUPPORTS_PAGE_TABLE_CHECK if MMU
>   	select ARCH_SUPPORTS_PER_VMA_LOCK if MMU
>

I found another bunch of LLD_VERSION check in this file that could be 
removed:

https://elixir.bootlin.com/linux/v6.17-rc2/source/arch/riscv/Kconfig#L253
https://elixir.bootlin.com/linux/v6.17-rc2/source/arch/riscv/Kconfig#L262
https://elixir.bootlin.com/linux/v6.17-rc2/source/arch/riscv/Kconfig#L630
https://elixir.bootlin.com/linux/v6.17-rc2/source/arch/riscv/Kconfig#L731
https://elixir.bootlin.com/linux/v6.17-rc2/source/arch/riscv/Kconfig#L746
https://elixir.bootlin.com/linux/v6.17-rc2/source/arch/riscv/Kconfig#L781
https://elixir.bootlin.com/linux/v6.17-rc2/source/arch/riscv/Kconfig#L804

Thanks,

Alex