linux-kernel - Re: [PATCH v4 10/15] x86: Implement ARCH_HAS_KERNEL_FPU

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Message-ID: <d2c3cd78-cdc6-4a39-9804-4f30402751b1@intel.com>
Date: Fri, 29 Mar 2024 10:28:44 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Samuel Holland <samuel.holland@...ive.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 linux-arm-kernel@...ts.infradead.org, x86@...nel.org
Cc: linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
 linuxppc-dev@...ts.ozlabs.org, linux-riscv@...ts.infradead.org,
 Christoph Hellwig <hch@....de>, loongarch@...ts.linux.dev,
 amd-gfx@...ts.freedesktop.org, Borislav Petkov <bp@...en8.de>,
 Dave Hansen <dave.hansen@...ux.intel.com>, Ingo Molnar <mingo@...hat.com>,
 Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v4 10/15] x86: Implement ARCH_HAS_KERNEL_FPU_SUPPORT

On 3/29/24 00:18, Samuel Holland wrote:
> +#
> +# CFLAGS for compiling floating point code inside the kernel.
> +#
> +CC_FLAGS_FPU := -msse -msse2
> +ifdef CONFIG_CC_IS_GCC
> +# Stack alignment mismatch, proceed with caution.
> +# GCC < 7.1 cannot compile code using `double` and -mpreferred-stack-boundary=3
> +# (8B stack alignment).
> +# See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383
> +#
> +# The "-msse" in the first argument is there so that the
> +# -mpreferred-stack-boundary=3 build error:
> +#
> +#  -mpreferred-stack-boundary=3 is not between 4 and 12
> +#
> +# can be triggered. Otherwise gcc doesn't complain.
> +CC_FLAGS_FPU += -mhard-float
> +CC_FLAGS_FPU += $(call cc-option,-msse -mpreferred-stack-boundary=3,-mpreferred-stack-boundary=4)
> +endif

I was expecting to see this (now duplicate) hunk come _out_ of
lib/Makefile somewhere in the series.

Did I miss that, or is there something keeping the duplicate there?