[PATCH] ARM: Do not select ARCH_HAS_KERNEL_FPU_SUPPORT

[Ard Biesheuvel]

On Thu, 9 May 2024 at 03:37, Samuel Holland <samuel.holland at sifive.com> wrote:
>
> On 32-bit ARM, conversions between `double` and `long long` require
> runtime library support. Since the kernel does not currently provide
> this library support, the amdgpu driver fails to build:
>
>   ERROR: modpost: "__aeabi_l2d" [drivers/gpu/drm/amd/amdgpu/amdgpu.ko] undefined!
>   ERROR: modpost: "__aeabi_d2ulz" [drivers/gpu/drm/amd/amdgpu/amdgpu.ko] undefined!
>
> As Arnd reports, there are likely no 32-bit ARM platforms which can use
> the amdgpu driver anyway, due to lack of features like 64-bit
> prefetchable BARs. Since amdgpu is currently the only real user of
> ARCH_HAS_KERNEL_FPU_SUPPORT, drop support for this option instead of
> bothering to implement the library functions.
>
> Fixes: 12624fe2d707 ("ARM: implement ARCH_HAS_KERNEL_FPU_SUPPORT")

This commit is not in mainline yet. Could we just drop the original
patch instead?

> Reported-by: Thiago Jung Bauermann <thiago.bauermann at linaro.org>
> Closes: https://lore.kernel.org/lkml/87wmp4oo3y.fsf@linaro.org/
> Reported-by: kernel test robot <lkp at intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202404042327.jRpt81kP-lkp@intel.com/
> Suggested-by: Ard Biesheuvel <ardb at kernel.org>
> Signed-off-by: Samuel Holland <samuel.holland at sifive.com>
> ---
>
>  arch/arm/Kconfig | 1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index b1751c2cab87..b14aed3a17ab 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -15,7 +15,6 @@ config ARM
>         select ARCH_HAS_FORTIFY_SOURCE
>         select ARCH_HAS_KEEPINITRD
>         select ARCH_HAS_KCOV
> -       select ARCH_HAS_KERNEL_FPU_SUPPORT if KERNEL_MODE_NEON
>         select ARCH_HAS_MEMBARRIER_SYNC_CORE
>         select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
>         select ARCH_HAS_PTE_SPECIAL if ARM_LPAE
> --
> 2.44.0
>