Re: [PATCH v7 4/4] target/riscv: add Zicbop cbo.prefetch{i, r, m} placeholder

[liweiwei]

On 2023/2/24 07:44, Daniel Henrique Barboza wrote:
> From: Christoph Muellner <cmuellner@linux.com>
>
> The cmo.prefetch instructions are nops for QEMU (no emulation of the
> memory hierarchy, no illegal instructions, no permission faults, no
> traps).
>
> Add a comment noting where they would be decoded in case cbo.prefetch
> instructions become relevant in the future.
>
> Co-developed-by: Philipp Tomsich <philipp.tomsich@vrull.eu>
> Signed-off-by: Christoph Muellner <cmuellner@linux.com>
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> ---

Reviewed-by: Weiwei Li <liweiwei@iscas.ac.cn>

Weiwei Li

>   target/riscv/insn32.decode | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/target/riscv/insn32.decode b/target/riscv/insn32.decode
> index 3788f86528..1aebd37572 100644
> --- a/target/riscv/insn32.decode
> +++ b/target/riscv/insn32.decode
> @@ -134,6 +134,7 @@ addi     ............     ..... 000 ..... 0010011 @i
>   slti     ............     ..... 010 ..... 0010011 @i
>   sltiu    ............     ..... 011 ..... 0010011 @i
>   xori     ............     ..... 100 ..... 0010011 @i
> +# cbo.prefetch_{i,r,m} instructions are ori with rd=x0 and not decoded.
>   ori      ............     ..... 110 ..... 0010011 @i
>   andi     ............     ..... 111 ..... 0010011 @i
>   slli     00000. ......    ..... 001 ..... 0010011 @sh