Date:   Tue, 14 Dec 2021 08:29:24 -0800 (PST)
Subject:     Re: [PATCH v9 05/17] riscv: Add vector feature to compile
In-Reply-To: <2684ea9e25a63c7a88faf46680a26e560027e444.1636362169.git.greentime.hu@sifive.com>
CC:     Paul Walmsley <paul.walmsley@sifive.com>,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        aou@eecs.berkeley.edu
From:   Palmer Dabbelt <palmer@dabbelt.com>
To:     greentime.hu@sifive.com
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On Tue, 09 Nov 2021 01:48:17 PST (-0800), greentime.hu@sifive.com wrote:
> From: Guo Ren <guoren@linux.alibaba.com>
>
> This patch adds a new config option which could enable assembler's
> vector feature.
>
> Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
> Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> Reviewed-by: Greentime Hu <greentime.hu@sifive.com>
> ---
>  arch/riscv/Kconfig  | 9 +++++++++
>  arch/riscv/Makefile | 1 +
>  2 files changed, 10 insertions(+)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index f076cee11af6..0311579920b9 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -389,6 +389,15 @@ config FPU
>
>  	  If you don't know what to do here, say Y.
>
> +config VECTOR
> +	bool "VECTOR support"
> +	default n
> +	help
> +	  Say N here if you want to disable all vector related procedure
> +	  in the kernel.
> +
> +	  If you don't know what to do here, say Y.
> +
>  endmenu

As the kernel build robot points out, this should have some sort of 
dependency on a vector toolchain.  Not sure if there's a better way to 
do it that cc-option, looks like there are some other tests for 
assembler arguments that way.

>
>  menu "Kernel features"
> diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> index 37de70df4fae..f109214a2d7f 100644
> --- a/arch/riscv/Makefile
> +++ b/arch/riscv/Makefile
> @@ -57,6 +57,7 @@ riscv-march-aflags-$(CONFIG_ARCH_RV32I)		:= rv32ima
>  riscv-march-aflags-$(CONFIG_ARCH_RV64I)		:= rv64ima
>  riscv-march-aflags-$(CONFIG_FPU)		:= $(riscv-march-aflags-y)fd
>  riscv-march-aflags-$(CONFIG_RISCV_ISA_C)	:= $(riscv-march-aflags-y)c
> +riscv-march-aflags-$(CONFIG_VECTOR)		:= $(riscv-march-aflags-y)v
>
>  KBUILD_CFLAGS += -march=$(riscv-march-cflags-y)
>  KBUILD_AFLAGS += -march=$(riscv-march-aflags-y)