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

Nathan Chancellor
2025-09-15T22:28:10Z

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)

Cheers,
Nathan