Re: [PATCH net-next V6] net/mlx5: Improve write-combining test reliability for ARM64 Grace CPUs

Sebastian Ott
2025-10-06T13:57:44Z

On Mon, 29 Sep 2025, Tariq Toukan wrote:
> +static void mlx5_iowrite64_copy(struct mlx5_wc_sq *sq, __be32 mmio_wqe[16],
> + size_t mmio_wqe_size, unsigned int offset)
> +{
> +#if IS_ENABLED(CONFIG_KERNEL_MODE_NEON) && IS_ENABLED(CONFIG_ARM64)
> + if (cpu_has_neon()) {
> + kernel_neon_begin();
> + asm volatile
> + (".arch_extension simd;\n\t"
> + "ld1 {v0.16b, v1.16b, v2.16b, v3.16b}, [%0]\n\t"
> + "st1 {v0.16b, v1.16b, v2.16b, v3.16b}, [%1]"
> + :
> + : "r"(mmio_wqe), "r"(sq->bfreg.map + offset)
> + : "memory", "v0", "v1", "v2", "v3");
> + kernel_neon_end();
> + return;
> + }
> +#endif

This one breaks the build for me:
/tmp/cc2vw3CJ.s: Assembler messages:
/tmp/cc2vw3CJ.s:391: Error: unknown architectural extension `simd;'

Removing the extra ";" after simd seems to fix it.

Regards,
Sebastian