linux-kernel - Re: [PATCH net-next V2] net/mlx5: Improve write-combining test reliability for ARM64 Grace CPUs

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Message-Id: <9d4cd8d2-343e-4448-ab59-65e69728c850@app.fastmail.com>
Date: Tue, 16 Sep 2025 10:58:32 +0200
From: "Arnd Bergmann" <arnd@...db.de>
To: "Patrisious Haddad" <phaddad@...dia.com>,
 "Nathan Chancellor" <nathan@...nel.org>, "Jason Gunthorpe" <jgg@...dia.com>
Cc: "Tariq Toukan" <tariqt@...dia.com>,
 "Catalin Marinas" <catalin.marinas@....com>,
 "Eric Dumazet" <edumazet@...gle.com>, "Jakub Kicinski" <kuba@...nel.org>,
 "Paolo Abeni" <pabeni@...hat.com>, "Andrew Lunn" <andrew+netdev@...n.ch>,
 "David S . Miller" <davem@...emloft.net>,
 "Saeed Mahameed" <saeedm@...dia.com>,
 "Leon Romanovsky" <leon@...nel.org>, "Mark Bloch" <mbloch@...dia.com>,
 "Sabrina Dubroca" <sd@...asysnail.net>, Netdev <netdev@...r.kernel.org>,
 linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
 "Gal Pressman" <gal@...dia.com>, "Leon Romanovsky" <leonro@...dia.com>,
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 "Heiko Carstens" <hca@...ux.ibm.com>, "H. Peter Anvin" <hpa@...or.com>,
 "Justin Stitt" <justinstitt@...gle.com>, linux-s390@...r.kernel.org,
 llvm@...ts.linux.dev, "Ingo Molnar" <mingo@...hat.com>,
 "Bill Wendling" <morbo@...gle.com>,
 "Nick Desaulniers" <ndesaulniers@...gle.com>,
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 "Yisen Zhuang" <yisen.zhuang@...wei.com>,
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 Linux-Arch <linux-arch@...r.kernel.org>,
 linux-arm-kernel@...ts.infradead.org,
 "Mark Rutland" <mark.rutland@....com>,
 "Michael Guralnik" <michaelgur@...lanox.com>, patches@...ts.linux.dev,
 "Niklas Schnelle" <schnelle@...ux.ibm.com>,
 "Jijie Shao" <shaojijie@...wei.com>
Subject: Re: [PATCH net-next V2] net/mlx5: Improve write-combining test reliability for
 ARM64 Grace CPUs

On Tue, Sep 16, 2025, at 10:39, Patrisious Haddad wrote:
> On 9/16/2025 2:15 AM, Nathan Chancellor wrote:
>> External email: Use caution opening links or attachments
>
> ifeq ($(ARCH),arm64)
>          CFLAGS_lib/neon_iowrite64_copy.o += -ffreestanding
>          CFLAGS_REMOVE_lib/neon_iowrite64_copy.o += -mgeneral-regs-only
> endif
>
> Which is actually equivalent to the diff you sent, Thanks for the 
> heads-up will fix and resend.
>

I think it's better to handle this inside of the inline asm itself
by adding

      ".arch_extension simd;\n\t"

at the start of it.

     Arnd