From: mark.rutland@arm.com (Mark Rutland)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] arm64: Kconfig: Enable LSE atomics by default
Date: Wed, 23 May 2018 09:42:55 +0100 [thread overview]
Message-ID: <20180523084254.ikpddax5ddbm4ajv@salmiak> (raw)
In-Reply-To: <1526926462-19214-1-git-send-email-will.deacon@arm.com>
On Mon, May 21, 2018 at 07:14:22PM +0100, Will Deacon wrote:
> Now that we're seeing CPUs shipping with LSE atomics, default them to
> 'on' in Kconfig. CPUs without the instructions will continue to use
> LDXR/STXR-based sequences, but they will be placed out-of-line by the
> compiler.
>
> Signed-off-by: Will Deacon <will.deacon@arm.com>
I've been fuzzing v4.17-rc3 with this enabled, and haven't hit anything new
that appears to be caused by the atomics. FWIW:
Acked-by: Mark Rutland <mark.rutland@arm.com>
Mark.
> ---
> arch/arm64/Kconfig | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 4d98774cf3c7..3aed13626fd7 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -1051,6 +1051,7 @@ config ARM64_PAN
>
> config ARM64_LSE_ATOMICS
> bool "Atomic instructions"
> + default y
> help
> As part of the Large System Extensions, ARMv8.1 introduces new
> atomic instructions that are designed specifically to scale in
> @@ -1059,7 +1060,8 @@ config ARM64_LSE_ATOMICS
> Say Y here to make use of these instructions for the in-kernel
> atomic routines. This incurs a small overhead on CPUs that do
> not support these instructions and requires the kernel to be
> - built with binutils >= 2.25.
> + built with binutils >= 2.25 in order for the new instructions
> + to be used.
>
> config ARM64_VHE
> bool "Enable support for Virtualization Host Extensions (VHE)"
> --
> 2.1.4
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2018-05-23 8:42 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-21 18:14 [PATCH] arm64: Kconfig: Enable LSE atomics by default Will Deacon
2018-05-22 14:29 ` Marc Zyngier
2018-05-23 8:42 ` Mark Rutland [this message]
2018-05-23 10:34 ` Catalin Marinas
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