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From: Jason Gunthorpe <jgg@nvidia.com>
To: Nathan Chancellor <nathan@kernel.org>
Cc: Tariq Toukan <tariqt@nvidia.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Andrew Lunn <andrew+netdev@lunn.ch>,
	"David S. Miller" <davem@davemloft.net>,
	Saeed Mahameed <saeedm@nvidia.com>,
	Leon Romanovsky <leon@kernel.org>, Mark Bloch <mbloch@nvidia.com>,
	Sabrina Dubroca <sd@queasysnail.net>,
	netdev@vger.kernel.org, linux-rdma@vger.kernel.org,
	linux-kernel@vger.kernel.org, Gal Pressman <gal@nvidia.com>,
	Leon Romanovsky <leonro@nvidia.com>,
	Michael Guralnik <michaelgur@nvidia.com>,
	Moshe Shemesh <moshe@nvidia.com>, Will Deacon <will@kernel.org>,
	Alexander Gordeev <agordeev@linux.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Christian Borntraeger <borntraeger@linux.ibm.com>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Heiko Carstens <hca@linux.ibm.com>,
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	Justin Stitt <justinstitt@google.com>,
	linux-s390@vger.kernel.org, llvm@lists.linux.dev,
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	Salil Mehta <salil.mehta@huawei.com>,
	Sven Schnelle <svens@linux.ibm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	x86@kernel.org, Yisen Zhuang <yisen.zhuang@huawei.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Leon Romanovsky <leonro@mellanox.com>,
	linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	Mark Rutland <mark.rutland@arm.com>,
	Michael Guralnik <michaelgur@mellanox.com>,
	patches@lists.linux.dev, Niklas Schnelle <schnelle@linux.ibm.com>,
	Jijie Shao <shaojijie@huawei.com>,
	Patrisious Haddad <phaddad@nvidia.com>
Subject: Re: [PATCH net-next V2] net/mlx5: Improve write-combining test reliability for ARM64 Grace CPUs
Date: Mon, 15 Sep 2025 19:48:10 -0300	[thread overview]
Message-ID: <20250915224810.GM1024672@nvidia.com> (raw)
In-Reply-To: <20250915222758.GC925462@ax162>

On Mon, Sep 15, 2025 at 03:27:58PM -0700, Nathan Chancellor wrote:
> On Mon, Sep 15, 2025 at 03:18:59PM -0700, Nathan Chancellor wrote:
> > On Mon, Sep 15, 2025 at 11:35:08AM +0300, Tariq Toukan wrote:
> > ...
> > > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/Makefile b/drivers/net/ethernet/mellanox/mlx5/core/Makefile
> > > index d77696f46eb5..06d0eb190816 100644
> > > --- a/drivers/net/ethernet/mellanox/mlx5/core/Makefile
> > > +++ b/drivers/net/ethernet/mellanox/mlx5/core/Makefile
> > > @@ -176,3 +176,9 @@ mlx5_core-$(CONFIG_PCIE_TPH) += lib/st.o
> > >  
> > >  obj-$(CONFIG_MLX5_DPLL) += mlx5_dpll.o
> > >  mlx5_dpll-y :=	dpll.o
> > > +
> > > +#
> > > +# NEON WC specific for mlx5
> > > +#
> > > +mlx5_core-$(CONFIG_KERNEL_MODE_NEON) += lib/wc_neon_iowrite64_copy.o
> > > +FLAGS_lib/wc_neon_iowrite64_copy.o += $(CC_FLAGS_FPU)
> > 
> > Does this work as is? I think this needs to be CFLAGS instead of FLAGS
> > but I did not test to verify.
> 
> Also, Documentation/core-api/floating-point.rst states that code should
> also use CFLAGS_REMOVE_ for CC_FLAGS_NO_FPU as well as adding
> CC_FLAGS_FPU.
> 
>   CFLAGS_REMOVE_lib/wc_neon_iowrite64_copy.o += $(CC_FLAGS_NO_FPU)

I wondered if you needed the seperate compilation unit at all since it
it all done with inline assembly.. Since the makefile seems to have a
typo, it suggests you don't need the compilation unit and it could
just be a little inline protected by CONFIG_KERNEL_MODE_NEON.

Jason

  reply	other threads:[~2025-09-15 22:48 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-09-15  8:35 [PATCH net-next V2] net/mlx5: Improve write-combining test reliability for ARM64 Grace CPUs Tariq Toukan
2025-09-15 22:18 ` Nathan Chancellor
2025-09-15 22:27   ` Nathan Chancellor
2025-09-15 22:48     ` Jason Gunthorpe [this message]
2025-09-15 23:15       ` Nathan Chancellor
2025-09-16  8:39         ` Patrisious Haddad
2025-09-16  8:58           ` Arnd Bergmann
2025-09-16  9:47             ` Patrisious Haddad
2025-09-16 12:27               ` Jason Gunthorpe
2025-09-16 13:13                 ` Patrisious Haddad

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