Re: [PATCH 1/4] target/riscv: Remove misa_mxl validation

[LIU Zhiwei]

On 2023/10/12 13:42, Akihiko Odaki wrote:
> It is initialized with a simple assignment and there is little room for
> error. In fact, the validation is even more complex.
>
> Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
> ---
>   target/riscv/cpu.c | 13 ++-----------
>   1 file changed, 2 insertions(+), 11 deletions(-)
>
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index f5572704de..550b357fb7 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -1042,7 +1042,7 @@ static void riscv_cpu_disable_priv_spec_isa_exts(RISCVCPU 
> *cpu)
>       }
>   }
>   
> -static void riscv_cpu_validate_misa_mxl(RISCVCPU *cpu, Error **errp)
> +static void riscv_cpu_validate_misa_mxl(RISCVCPU *cpu)
>   {
>       RISCVCPUClass *mcc = RISCV_CPU_GET_CLASS(cpu);
>       CPUClass *cc = CPU_CLASS(mcc);
> @@ -1062,11 +1062,6 @@ static void riscv_cpu_validate_misa_mxl(RISCVCPU *cpu, 
> Error **errp)
>       default:
>           g_assert_not_reached();
>       }
> -
> -    if (env->misa_mxl_max != env->misa_mxl) {
> -        error_setg(errp, "misa_mxl_max must be equal to misa_mxl");
> -        return;
> -    }
>   }
>   
>   /*
> @@ -1447,11 +1442,7 @@ static void riscv_cpu_realize_tcg(DeviceState *dev, 
> Error **errp)
>           return;
>       }
>   
> -    riscv_cpu_validate_misa_mxl(cpu, &local_err);
> -    if (local_err != NULL) {
> -        error_propagate(errp, local_err);
> -        return;
> -    }
> +    riscv_cpu_validate_misa_mxl(cpu);

This it not right.  As we are still working on the supporting for MXL32 
or SXL32, this validation is needed.

And we can't ensure the all RISC-V cpus have the same misa_mxl_max or 
misa_mxl,   it is not right to move it to class.
For example, in the future, riscv64-softmmu can run 32-bit cpu and 
64-bit cpu. And maybe in heterogeneous SOC,
we have 32-bit cpu and 64-bit cpu together.

I am afraid that we can not accept this patch set.

Thanks,
Zhiwei

>   
>       riscv_cpu_validate_priv_spec(cpu, &local_err);
>       if (local_err != NULL) {